// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.

package model

import (
	"crypto"
	"crypto/aes"
	"crypto/cipher"
	"crypto/ecdsa"
	"crypto/rand"
	"encoding/asn1"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"maps"
	"math/big"
	"net/http"
	"net/url"
	"reflect"
	"regexp"
	"slices"
	"strconv"
	"strings"
	"time"

	"github.com/hashicorp/go-multierror"
	"github.com/pkg/errors"
)

const (
	PostActionTypeButton              = "button"
	PostActionTypeSelect              = "select"
	DialogTitleMaxLength              = 80
	DialogElementDisplayNameMaxLength = 24
	DialogElementNameMaxLength        = 300
	DialogElementHelpTextMaxLength    = 150
	DialogElementTextMaxLength        = 150
	DialogElementTextareaMaxLength    = 3000
	DialogElementSelectMaxLength      = 3000
	DialogElementBoolMaxLength        = 150
	DialogElementFileMaxLength        = 300
	DefaultTimeIntervalMinutes        = 60 // Default time interval for DateTime fields
	DialogCollapsibleMaxDepth         = 3  // Maximum levels of nested collapsible sections (top-level collapsible is depth 1)
	MaxDialogCheckboxGroupOptions     = 50
	MaxDialogMatrixRows               = 30
	MaxDialogMatrixColumns            = 10
	DialogLabelPositionBefore         = "before"
	DialogLabelPositionAfter          = "after"
	DialogMatrixRowSelectionMultiple  = "multiple"
	DialogMatrixRowSelectionSingle    = "single"
	MaxDialogFileIds                  = 10
	// MaxDialogSubmissionIDShapedTokenScan bounds defense-in-depth scanning of
	// request.Submission for ID-shaped tokens (file IDs, user/channel select values,
	// etc.). This is not the per-dialog file upload limit — see MaxDialogFileIds.
	MaxDialogSubmissionIDShapedTokenScan = 256

	// Go date/time format constants
	ISODateFormat                 = "2006-01-02"                // YYYY-MM-DD
	ISODateTimeFormat             = "2006-01-02T15:04:05Z"      // RFC3339 UTC
	ISODateTimeWithTimezoneFormat = "2006-01-02T15:04:05-07:00" // RFC3339 with timezone
	ISODateTimeNoTimezoneFormat   = "2006-01-02T15:04:05"       // ISO datetime without timezone
	ISODateTimeNoSecondsFormat    = "2006-01-02T15:04"          // ISO datetime without seconds
)

// Common datetime formats used by both date and datetime validation
var commonDateTimeFormats = []string{
	ISODateTimeFormat,             // RFC3339 UTC
	ISODateTimeWithTimezoneFormat, // RFC3339 with timezone
	ISODateTimeNoTimezoneFormat,   // ISO datetime without timezone
	ISODateTimeNoSecondsFormat,    // ISO datetime without seconds
}

var PostActionRetainPropKeys = []string{
	PostPropsFromWebhook,
	PostPropsFromBot,
	PostPropsFromPlugin,
	PostPropsOverrideUsername,
	PostPropsOverrideIconURL,
	PostPropsOverrideIconEmoji,
	PostPropsWebhookDisplayName,
}

// PostActionPreserve captures post fields preserved across an interactive action update.
type PostActionPreserve struct {
	Retain               map[string]any
	Remove               []string
	OriginalProps        map[string]any
	OriginalIsPinned     bool
	OriginalHasReactions bool
	RootPostId           string
}

// PostActionPreserveState returns retain/remove props and metadata used when applying integration responses.
func (o *Post) PostActionPreserveState() PostActionPreserve {
	retain := map[string]any{}
	remove := []string{}
	for _, key := range PostActionRetainPropKeys {
		value, ok := o.GetProps()[key]
		if ok {
			retain[key] = value
		} else {
			remove = append(remove, key)
		}
	}
	rootPostId := o.Id
	if o.RootId != "" {
		rootPostId = o.RootId
	}
	var originalProps map[string]any
	if props := o.GetProps(); props != nil {
		originalProps = make(map[string]any, len(props))
		maps.Copy(originalProps, props)
	}
	return PostActionPreserve{
		Retain:               retain,
		Remove:               remove,
		OriginalProps:        originalProps,
		OriginalIsPinned:     o.IsPinned,
		OriginalHasReactions: o.HasReactions,
		RootPostId:           rootPostId,
	}
}

type DoPostActionRequest struct {
	SelectedOption string            `json:"selected_option,omitempty"`
	Cookie         string            `json:"cookie,omitempty"`
	Query          map[string]string `json:"query,omitempty"`
	// IntegrationFormat identifies which format originally had the action (attachment, mm_block, ...).
	// Empty means a legacy client and is treated as attachment.
	IntegrationFormat string `json:"integration_format,omitempty"`
}

// Integration format values for DoPostActionRequest.IntegrationFormat (client → server).
const (
	PostActionIntegrationFormatAttachment  = "attachment"
	PostActionIntegrationFormatAppsBinding = "apps_binding"
	PostActionIntegrationFormatBlock       = "block"
	PostActionIntegrationFormatCard        = "card"
	PostActionIntegrationFormatMmBlock     = "mm_block"
)

// NormalizePostActionIntegrationFormat returns a canonical integration format, defaulting to attachment when empty or unknown.
func NormalizePostActionIntegrationFormat(s string) string {
	c := strings.TrimSpace(strings.ToLower(s))
	switch c {
	case PostActionIntegrationFormatMmBlock,
		PostActionIntegrationFormatAppsBinding,
		PostActionIntegrationFormatBlock,
		PostActionIntegrationFormatCard:
		return c
	case PostActionIntegrationFormatAttachment, "":
		return PostActionIntegrationFormatAttachment
	default:
		return PostActionIntegrationFormatAttachment
	}
}

const (
	PostActionDataSourceUsers    = "users"
	PostActionDataSourceChannels = "channels"

	MaxMmBlocksActionsPerPost  = 50
	MaxMmBlocksActionKeyLength = 64

	MaxActionQueryEntries     = 50
	MaxActionQueryKeyLength   = 128
	MaxActionQueryValueLength = 2048
)

type PostAction struct {
	// A unique Action ID. If not set, generated automatically.
	Id string `json:"id,omitempty"`

	// The type of the interactive element. Currently supported are
	// "select" and "button".
	Type string `json:"type,omitempty"`

	// The text on the button, or in the select placeholder.
	Name string `json:"name,omitempty"`

	// Tooltip text displayed on hover.
	Tooltip string `json:"tooltip,omitempty"`

	// If the action is disabled.
	Disabled bool `json:"disabled,omitempty"`

	// Style defines a text and border style.
	// Supported values are "default", "primary", "success", "good", "warning", "danger"
	// and any hex color.
	Style string `json:"style,omitempty"`

	// DataSource indicates the data source for the select action. If left
	// empty, the select is populated from Options. Other supported values
	// are "users" and "channels".
	DataSource string `json:"data_source,omitempty"`

	// Options contains the values listed in a select dropdown on the post.
	Options []*PostActionOptions `json:"options,omitempty"`

	// DefaultOption contains the option, if any, that will appear as the
	// default selection in a select box. It has no effect when used with
	// other types of actions.
	DefaultOption string `json:"default_option,omitempty"`

	// Defines the interaction with the backend upon a user action.
	// Integration contains Context, which is private plugin data;
	// Integrations are stripped from Posts when they are sent to the
	// client, or are encrypted in a Cookie.
	Integration *PostActionIntegration `json:"integration,omitempty"`
	Cookie      string                 `json:"cookie,omitempty" db:"-"`
}

// IsValid validates the action and returns an error if it is invalid.
func (p *PostAction) IsValid() error {
	var multiErr *multierror.Error

	if p.Name == "" {
		multiErr = multierror.Append(multiErr, fmt.Errorf("action must have a name"))
	}

	if p.Style != "" {
		validStyles := []string{"default", "primary", "success", "good", "warning", "danger"}
		// If not a predefined style, check if it's a hex color
		if !slices.Contains(validStyles, p.Style) && !hexColorRegex.MatchString(p.Style) {
			multiErr = multierror.Append(multiErr, fmt.Errorf("invalid style '%s' - must be one of [default, primary, success, good, warning, danger] or a hex color", p.Style))
		}
	}

	switch p.Type {
	case PostActionTypeButton:
		if len(p.Options) > 0 {
			multiErr = multierror.Append(multiErr, fmt.Errorf("button action must not have options"))
		}
		if p.DataSource != "" {
			multiErr = multierror.Append(multiErr, fmt.Errorf("button action must not have a data source"))
		}
	case PostActionTypeSelect:
		if p.DataSource != "" {
			validSources := []string{PostActionDataSourceUsers, PostActionDataSourceChannels}
			if !slices.Contains(validSources, p.DataSource) {
				multiErr = multierror.Append(multiErr, fmt.Errorf("invalid data_source '%s' for select action", p.DataSource))
			}

			if len(p.Options) > 0 {
				multiErr = multierror.Append(multiErr, fmt.Errorf("select action cannot have both DataSource and Options set"))
			}
		} else {
			if len(p.Options) == 0 {
				multiErr = multierror.Append(multiErr, fmt.Errorf("select action must have either DataSource or Options set"))
			} else {
				for i, opt := range p.Options {
					if opt == nil {
						multiErr = multierror.Append(multiErr, fmt.Errorf("select action contains nil option"))
						continue
					}
					if err := opt.IsValid(); err != nil {
						multiErr = multierror.Append(multiErr, multierror.Prefix(err, fmt.Sprintf("option at index %d is invalid:", i)))
					}
				}
			}
		}
	default:
		multiErr = multierror.Append(multiErr, fmt.Errorf("invalid action type: must be '%s' or '%s'", PostActionTypeButton, PostActionTypeSelect))
	}

	if p.Integration == nil {
		multiErr = multierror.Append(multiErr, fmt.Errorf("action must have integration settings"))
	} else {
		if p.Integration.URL == "" {
			multiErr = multierror.Append(multiErr, fmt.Errorf("action must have an integration URL"))
		}
		if !(strings.HasPrefix(p.Integration.URL, "/plugins/") || strings.HasPrefix(p.Integration.URL, "plugins/") || IsValidHTTPURL(p.Integration.URL)) {
			multiErr = multierror.Append(multiErr, fmt.Errorf("action must have an valid integration URL"))
		}
	}

	return multiErr.ErrorOrNil()
}

func (p *PostAction) Equals(input *PostAction) bool {
	if p.Id != input.Id {
		return false
	}

	if p.Type != input.Type {
		return false
	}

	if p.Name != input.Name {
		return false
	}

	if p.DataSource != input.DataSource {
		return false
	}

	if p.DefaultOption != input.DefaultOption {
		return false
	}

	if p.Cookie != input.Cookie {
		return false
	}

	// Compare PostActionOptions
	if len(p.Options) != len(input.Options) {
		return false
	}

	for k := range p.Options {
		if p.Options[k].Text != input.Options[k].Text {
			return false
		}

		if p.Options[k].Value != input.Options[k].Value {
			return false
		}
	}

	// Compare PostActionIntegration

	// If input is nil, then return true if original is also nil.
	// Else return false.
	if input.Integration == nil {
		return p.Integration == nil
	}

	// At this point, input is not nil, so return false if original is.
	if p.Integration == nil {
		return false
	}

	// Both are unequal and not nil.
	if p.Integration.URL != input.Integration.URL {
		return false
	}

	if len(p.Integration.Context) != len(input.Integration.Context) {
		return false
	}

	for key, value := range p.Integration.Context {
		inputValue, ok := input.Integration.Context[key]
		if !ok {
			return false
		}

		switch inputValue.(type) {
		case string, bool, int, float64:
			if value != inputValue {
				return false
			}
		default:
			if !reflect.DeepEqual(value, inputValue) {
				return false
			}
		}
	}

	return true
}

// PostActionCookie is set by the server, serialized and encrypted into
// PostAction.Cookie. The clients should hold on to it, and include it with
// subsequent DoPostAction requests. This allows the server to access the
// action metadata even when it's not available in the database, for ephemeral
// posts. Used for attachment-based interactive messages (legacy PostAction shape).
//
// mm_blocks uses [MmBlocksActionCookie] instead; see mm_blocks_actions.go.
type PostActionCookie struct {
	Type        string                 `json:"type,omitempty"`
	PostId      string                 `json:"post_id,omitempty"`
	RootPostId  string                 `json:"root_post_id,omitempty"`
	ChannelId   string                 `json:"channel_id,omitempty"`
	DataSource  string                 `json:"data_source,omitempty"`
	Integration *PostActionIntegration `json:"integration,omitempty"`
	RetainProps map[string]any         `json:"retain_props,omitempty"`
	RemoveProps []string               `json:"remove_props,omitempty"`
}

// MmBlocksActionCookieKind is the JSON "kind" discriminator for [MmBlocksActionCookie] payloads.
const MmBlocksActionCookieKind = "mm_blocks_actions"

// MmBlocksActionCookie is the decrypted cookie payload for mm_blocks interactive messages
// (encrypted into props.mm_blocks_actions for clients). It mirrors the shared post/channel
// metadata of [PostActionCookie] but carries props.mm_blocks_actions as an actions map instead
// of a single PostAction integration.
type MmBlocksActionCookie struct {
	Kind        string                    `json:"kind,omitempty"`
	PostId      string                    `json:"post_id,omitempty"`
	RootPostId  string                    `json:"root_post_id,omitempty"`
	ChannelId   string                    `json:"channel_id,omitempty"`
	RetainProps map[string]any            `json:"retain_props,omitempty"`
	RemoveProps []string                  `json:"remove_props,omitempty"`
	Actions     map[string]map[string]any `json:"actions"`
}

type PostActionOptions struct {
	Text  string `json:"text"`
	Value string `json:"value"`
}

func (o *PostActionOptions) IsValid() error {
	var multiErr *multierror.Error

	if o.Text == "" {
		multiErr = multierror.Append(multiErr, fmt.Errorf("text is required"))
	}
	if o.Value == "" {
		multiErr = multierror.Append(multiErr, fmt.Errorf("value is required"))
	}

	return multiErr.ErrorOrNil()
}

type PostActionIntegration struct {
	// URL is the endpoint that the action will be sent to.
	// It can be a relative path to a plugin.
	URL     string         `json:"url,omitempty"`
	Context map[string]any `json:"context,omitempty"`
}

type PostActionIntegrationRequest struct {
	UserId      string         `json:"user_id"`
	UserName    string         `json:"user_name"`
	ChannelId   string         `json:"channel_id"`
	ChannelName string         `json:"channel_name"`
	TeamId      string         `json:"team_id"`
	TeamName    string         `json:"team_domain"`
	PostId      string         `json:"post_id"`
	TriggerId   string         `json:"trigger_id"`
	Type        string         `json:"type"`
	DataSource  string         `json:"data_source"`
	Context     map[string]any `json:"context,omitempty"`
}

type PostActionIntegrationResponse struct {
	Update           *Post  `json:"update"`
	EphemeralText    string `json:"ephemeral_text"`
	SkipSlackParsing bool   `json:"skip_slack_parsing"` // Set to `true` to skip the Slack-compatibility handling of Text.
	GotoLocation     string `json:"goto_location,omitempty"`
}

type PostActionAPIResponse struct {
	Status       string `json:"status"` // needed to maintain backwards compatibility
	TriggerId    string `json:"trigger_id"`
	GotoLocation string `json:"goto_location,omitempty"`
}

type ExecuteDialogActionResponse struct {
	TriggerId string `json:"trigger_id"`
}

type Dialog struct {
	CallbackId       string          `json:"callback_id"`
	Title            string          `json:"title"`
	IntroductionText string          `json:"introduction_text"`
	IconURL          string          `json:"icon_url"`
	Elements         []DialogElement `json:"elements"`
	SubmitLabel      string          `json:"submit_label"`
	NotifyOnCancel   bool            `json:"notify_on_cancel"`
	State            string          `json:"state"`
	SourceURL        string          `json:"source_url,omitempty"`
}

// DialogDateTimeConfig groups date/datetime specific configuration
type DialogDateTimeConfig struct {
	// MinDate: Minimum allowed date (ISO date, datetime, or relative like "+2H", "today")
	MinDate string `json:"min_date,omitempty"`
	// MaxDate: Maximum allowed date (ISO date, datetime, or relative like "+7d", "tomorrow")
	MaxDate string `json:"max_date,omitempty"`
	// TimeInterval: Minutes between time options in dropdown (default: 60)
	TimeInterval int `json:"time_interval,omitempty"`
	// LocationTimezone: IANA timezone for display (e.g., "America/Denver", "Asia/Tokyo")
	LocationTimezone string `json:"location_timezone,omitempty"`
	// ManualTimeEntry: Allow manual text entry for time instead of dropdown
	ManualTimeEntry bool `json:"manual_time_entry,omitempty"`
}

// DialogMatrixConfig groups checkbox_matrix specific configuration.
type DialogMatrixConfig struct {
	Rows         []*PostActionOptions `json:"rows"`
	Columns      []*PostActionOptions `json:"columns"`
	RowSelection string               `json:"row_selection,omitempty"` // "multiple" | "single"
}

type DialogElement struct {
	DisplayName   string               `json:"display_name"`
	Name          string               `json:"name"`
	Type          string               `json:"type"`
	SubType       string               `json:"subtype"`
	Default       string               `json:"default"`
	Placeholder   string               `json:"placeholder"`
	HelpText      string               `json:"help_text"`
	Optional      bool                 `json:"optional"`
	MinLength     int                  `json:"min_length"`
	MaxLength     int                  `json:"max_length"`
	DataSource    string               `json:"data_source"`
	DataSourceURL string               `json:"data_source_url,omitempty"`
	Options       []*PostActionOptions `json:"options"`
	MultiSelect   bool                 `json:"multiselect"`
	AllowMultiple bool                 `json:"allow_multiple,omitempty"`
	Refresh       bool                 `json:"refresh,omitempty"`

	// CollapsibleConfig holds child elements and display options for a
	// "collapsible" element. Nil for all other element types.
	CollapsibleConfig *DialogElementCollapsibleConfig `json:"collapsible_config,omitempty"`

	// Date/datetime field configuration
	DateTimeConfig *DialogDateTimeConfig `json:"datetime_config,omitempty"`

	LabelPosition string              `json:"label_position,omitempty"` // "before" | "after"
	MatrixConfig  *DialogMatrixConfig `json:"matrix_config,omitempty"`
	// Action button configuration (type "action_button")
	ActionButton *DialogActionButton `json:"action_button,omitempty"`
}

// EffectiveDateTimeConfig returns the resolved date/datetime configuration,
// treating a nil DateTimeConfig as the zero value.
func (e *DialogElement) EffectiveDateTimeConfig() DialogDateTimeConfig {
	if e.DateTimeConfig != nil {
		return *e.DateTimeConfig
	}
	return DialogDateTimeConfig{}
}

// EffectiveMatrixConfig returns the resolved checkbox_matrix configuration.
func (e *DialogElement) EffectiveMatrixConfig() DialogMatrixConfig {
	if e.MatrixConfig == nil {
		return DialogMatrixConfig{RowSelection: DialogMatrixRowSelectionMultiple}
	}
	cfg := *e.MatrixConfig
	if cfg.RowSelection == "" {
		cfg.RowSelection = DialogMatrixRowSelectionMultiple
	}
	return cfg
}

type DialogActionButton struct {
	URL     string            `json:"url"`
	Context map[string]string `json:"context,omitempty"`
}

type DialogElementCollapsibleConfig struct {
	// Elements are the child elements rendered inside the collapsible section.
	Elements []DialogElement `json:"elements,omitempty"`
	// Collapsed controls the initial open/closed state. False means expanded.
	Collapsed bool `json:"collapsed,omitempty"`
	// Borderless controls whether the section renders without a box outline.
	Borderless bool `json:"borderless,omitempty"`
}

type OpenDialogRequest struct {
	TriggerId string `json:"trigger_id"`
	URL       string `json:"url"`
	Dialog    Dialog `json:"dialog"`

	// ChannelId is populated by the server from the trigger and sent to the client,
	// which echoes it back on submit so the submission targets the correct channel.
	ChannelId string `json:"channel_id,omitempty"`
}

type SubmitDialogRequest struct {
	Type       string         `json:"type"`
	URL        string         `json:"url,omitempty"`
	CallbackId string         `json:"callback_id"`
	State      string         `json:"state"`
	UserId     string         `json:"user_id"`
	ChannelId  string         `json:"channel_id"`
	TeamId     string         `json:"team_id"`
	Submission map[string]any `json:"submission"`
	Cancelled  bool           `json:"cancelled"`
	FileIds    []string       `json:"file_ids,omitempty"`
}

type SubmitDialogResponseType string

const (
	SubmitDialogResponseTypeEmpty    SubmitDialogResponseType = ""
	SubmitDialogResponseTypeOK       SubmitDialogResponseType = "ok"
	SubmitDialogResponseTypeForm     SubmitDialogResponseType = "form"
	SubmitDialogResponseTypeNavigate SubmitDialogResponseType = "navigate"
)

type SubmitDialogResponse struct {
	Error  string            `json:"error,omitempty"`
	Errors map[string]string `json:"errors,omitempty"`
	Type   string            `json:"type,omitempty"`
	Form   *Dialog           `json:"form,omitempty"`
}

type ExecuteDialogActionRequest struct {
	URL       string            `json:"url"`
	Context   map[string]string `json:"context,omitempty"`
	ChannelId string            `json:"channel_id"`
	TeamId    string            `json:"team_id"`
}

func (r *SubmitDialogResponse) IsValid() error {
	// If Error or Errors are set, this is valid and everything else is ignored
	if r.Error != "" || len(r.Errors) > 0 {
		return nil
	}

	// Validate Type field and handle Form field appropriately for each type
	switch SubmitDialogResponseType(r.Type) {
	case SubmitDialogResponseTypeEmpty, SubmitDialogResponseTypeOK, SubmitDialogResponseTypeNavigate:
		// Completion types - Form field should be nil
		if r.Form != nil {
			return errors.Errorf("form field must be nil for type %q", r.Type)
		}
	case SubmitDialogResponseTypeForm:
		// Continuation type - Form field is required and must be valid
		if r.Form == nil {
			return errors.New("form field is required for form type")
		}
		if err := r.Form.IsValid(); err != nil {
			return errors.Wrap(err, "invalid form")
		}
	default:
		return errors.Errorf("invalid type %q, must be one of: empty, ok, form, navigate", r.Type)
	}

	return nil
}

// DialogSelectOption represents an option in a select dropdown for dialogs
type DialogSelectOption struct {
	Text  string `json:"text"`
	Value string `json:"value"`
}

// LookupDialogResponse represents the response for a lookup dialog request.
type LookupDialogResponse struct {
	Items []DialogSelectOption `json:"items"`
}

// signForGenerateTriggerId wraps the signing operation with panic recovery
// to handle invalid signers that may cause panics in the crypto package
func signForGenerateTriggerId(s crypto.Signer, digest []byte, opts crypto.SignerOpts) (signature []byte, err error) {
	defer func() {
		if r := recover(); r != nil {
			signature = nil
			err = fmt.Errorf("invalid signing key: %v", r)
		}
	}()

	return s.Sign(rand.Reader, digest, opts)
}

// GenerateTriggerId signs the context an interactive dialog needs on submit.
func GenerateTriggerId(userId, channelId string, s crypto.Signer) (string, string, *AppError) {
	clientTriggerId := NewId()
	triggerData := strings.Join([]string{clientTriggerId, userId, strconv.FormatInt(GetMillis(), 10), channelId}, ":") + ":"

	h := crypto.SHA256
	sum := h.New()
	sum.Write([]byte(triggerData))
	signature, err := signForGenerateTriggerId(s, sum.Sum(nil), h)
	if err != nil {
		return "", "", NewAppError("GenerateTriggerId", "interactive_message.generate_trigger_id.signing_failed", nil, "", http.StatusInternalServerError).Wrap(err)
	}

	base64Sig := base64.StdEncoding.EncodeToString(signature)

	triggerId := base64.StdEncoding.EncodeToString([]byte(triggerData + base64Sig))
	return clientTriggerId, triggerId, nil
}

func (r *PostActionIntegrationRequest) GenerateTriggerId(s crypto.Signer) (string, string, *AppError) {
	clientTriggerId, triggerId, appErr := GenerateTriggerId(r.UserId, r.ChannelId, s)
	if appErr != nil {
		return "", "", appErr
	}

	r.TriggerId = triggerId
	return clientTriggerId, triggerId, nil
}

// DecodeAndVerifyTriggerId returns the client trigger ID, the user the trigger was
// minted for, and the channel it originated in.
func DecodeAndVerifyTriggerId(triggerId string, s *ecdsa.PrivateKey, timeout time.Duration) (string, string, string, *AppError) {
	triggerIdBytes, err := base64.StdEncoding.DecodeString(triggerId)
	if err != nil {
		return "", "", "", NewAppError("DecodeAndVerifyTriggerId", "interactive_message.decode_trigger_id.base64_decode_failed", nil, "", http.StatusBadRequest).Wrap(err)
	}

	split := strings.Split(string(triggerIdBytes), ":")
	if len(split) < 5 {
		return "", "", "", NewAppError("DecodeAndVerifyTriggerId", "interactive_message.decode_trigger_id.missing_data", nil, "", http.StatusBadRequest)
	}

	clientTriggerId := split[0]
	userId := split[1]
	timestampStr := split[2]
	timestamp, _ := strconv.ParseInt(timestampStr, 10, 64)
	channelId := split[3]
	signatureStr := split[len(split)-1]

	if time.Since(time.UnixMilli(timestamp)) > timeout {
		return "", "", "", NewAppError("DecodeAndVerifyTriggerId", "interactive_message.decode_trigger_id.expired", map[string]any{"Duration": timeout.String()}, "", http.StatusBadRequest)
	}

	signature, err := base64.StdEncoding.DecodeString(signatureStr)
	if err != nil {
		return "", "", "", NewAppError("DecodeAndVerifyTriggerId", "interactive_message.decode_trigger_id.base64_decode_failed_signature", nil, "", http.StatusBadRequest).Wrap(err)
	}

	var esig struct {
		R, S *big.Int
	}

	if _, err := asn1.Unmarshal(signature, &esig); err != nil {
		return "", "", "", NewAppError("DecodeAndVerifyTriggerId", "interactive_message.decode_trigger_id.signature_decode_failed", nil, "", http.StatusBadRequest).Wrap(err)
	}

	triggerData := strings.Join(split[:len(split)-1], ":") + ":"

	h := crypto.SHA256
	sum := h.New()
	sum.Write([]byte(triggerData))

	if !ecdsa.Verify(&s.PublicKey, sum.Sum(nil), esig.R, esig.S) {
		return "", "", "", NewAppError("DecodeAndVerifyTriggerId", "interactive_message.decode_trigger_id.verify_signature_failed", nil, "", http.StatusBadRequest)
	}

	return clientTriggerId, userId, channelId, nil
}

func (r *OpenDialogRequest) DecodeAndVerifyTriggerId(s *ecdsa.PrivateKey, timeout time.Duration) (string, string, string, *AppError) {
	return DecodeAndVerifyTriggerId(r.TriggerId, s, timeout)
}

func (r *OpenDialogRequest) IsValid() error {
	var multiErr *multierror.Error
	if r.URL == "" {
		multiErr = multierror.Append(multiErr, errors.New("empty URL"))
	}

	if r.TriggerId == "" {
		multiErr = multierror.Append(multiErr, errors.New("empty trigger id"))
	}

	err := r.Dialog.IsValid()
	if err != nil {
		multiErr = multierror.Append(multiErr, err)
	}

	return multiErr.ErrorOrNil()
}

func (d *Dialog) IsValid() error {
	var multiErr *multierror.Error

	if d.Title == "" || len(d.Title) > DialogTitleMaxLength {
		multiErr = multierror.Append(multiErr, errors.Errorf("invalid dialog title %q", d.Title))
	}

	if d.IconURL != "" && !IsValidHTTPURL(d.IconURL) {
		multiErr = multierror.Append(multiErr, errors.New("invalid icon url"))
	}

	if len(d.Elements) != 0 {
		elementMap := make(map[string]bool)

		for _, element := range d.Elements {
			if elementMap[element.Name] {
				multiErr = multierror.Append(multiErr, errors.Errorf("duplicate dialog element %q", element.Name))
			}
			elementMap[element.Name] = true

			err := element.isValid(elementMap)
			if err != nil {
				multiErr = multierror.Append(multiErr, errors.Wrapf(err, "%q field is not valid", element.Name))
			}
		}
	}
	return multiErr.ErrorOrNil()
}

func (e *DialogElement) IsValid() error {
	seen := make(map[string]bool)
	if e.Name != "" {
		seen[e.Name] = true
	}
	return e.isValid(seen)
}

// isValid validates the element, threading a shared seen-name set through
// recursive validation of collapsible children so duplicate names are detected
// across the whole element tree, not just at the top level.
func (e *DialogElement) isValid(seen map[string]bool) error {
	var multiErr *multierror.Error
	textSubTypes := map[string]bool{
		"":         true,
		"text":     true,
		"email":    true,
		"number":   true,
		"tel":      true,
		"url":      true,
		"password": true,
	}

	multiErr = multierror.Append(multiErr, e.validateCommon())

	multiErr = multierror.Append(multiErr, validateDialogElementLabelPosition(e))
	multiErr = multierror.Append(multiErr, validateDialogElementMatrixConfigPlacement(e))

	if e.AllowMultiple && e.Type != "file" {
		multiErr = multierror.Append(multiErr, errors.Errorf("allow_multiple can only be used with file elements, got type %q", e.Type))
	}

	switch e.Type {
	case "text":
		multiErr = multierror.Append(multiErr, checkMaxLength("Default", e.Default, DialogElementTextMaxLength))
		multiErr = multierror.Append(multiErr, checkMaxLength("Placeholder", e.Placeholder, DialogElementTextMaxLength))
		if _, ok := textSubTypes[e.SubType]; !ok {
			multiErr = multierror.Append(multiErr, errors.Errorf("invalid subtype %q", e.Type))
		}

	case "textarea":
		multiErr = multierror.Append(multiErr, checkMaxLength("Default", e.Default, DialogElementTextareaMaxLength))
		multiErr = multierror.Append(multiErr, checkMaxLength("Placeholder", e.Placeholder, DialogElementTextareaMaxLength))

		if _, ok := textSubTypes[e.SubType]; !ok {
			multiErr = multierror.Append(multiErr, errors.Errorf("invalid subtype %q", e.Type))
		}

	case "select":
		multiErr = multierror.Append(multiErr, checkMaxLength("Default", e.Default, DialogElementSelectMaxLength))
		multiErr = multierror.Append(multiErr, checkMaxLength("Placeholder", e.Placeholder, DialogElementSelectMaxLength))
		if e.DataSource != "" && e.DataSource != "users" && e.DataSource != "channels" && e.DataSource != "dynamic" {
			multiErr = multierror.Append(multiErr, errors.Errorf("invalid data source %q, allowed are 'users', 'channels', or 'dynamic'", e.DataSource))
		}
		if e.DataSource == "dynamic" {
			// Dynamic selects should have a data_source_url
			if e.DataSourceURL == "" {
				multiErr = multierror.Append(multiErr, errors.New("dynamic data_source requires data_source_url"))
			} else if !IsValidLookupURL(e.DataSourceURL) {
				multiErr = multierror.Append(multiErr, errors.New("invalid data_source_url for dynamic select"))
			}
			// Dynamic selects should not have static options
			if len(e.Options) > 0 {
				multiErr = multierror.Append(multiErr, errors.New("dynamic select element should not have static options"))
			}
		} else if e.DataSource == "" {
			if e.MultiSelect {
				if !isMultiSelectDefaultInOptions(e.Default, e.Options) {
					multiErr = multierror.Append(multiErr, errors.Errorf("multiselect default value %q contains values not in options", e.Default))
				}
			} else if !isDefaultInOptions(e.Default, e.Options) {
				multiErr = multierror.Append(multiErr, errors.Errorf("default value %q doesn't exist in options ", e.Default))
			}
		}

	case "bool":
		if e.Default != "" && e.Default != "true" && e.Default != "false" {
			multiErr = multierror.Append(multiErr, errors.New("invalid default of bool"))
		}
		multiErr = multierror.Append(multiErr, checkMaxLength("Placeholder", e.Placeholder, DialogElementBoolMaxLength))

	case "radio":
		if !isDefaultInOptions(e.Default, e.Options) {
			multiErr = multierror.Append(multiErr, errors.Errorf("default value %q doesn't exist in options ", e.Default))
		}

	case "checkbox_group":
		multiErr = multierror.Append(multiErr, validateDialogElementOptions(e.Options, 1, MaxDialogCheckboxGroupOptions, "options", ",")...)
		multiErr = multierror.Append(multiErr, checkMaxLength("Default", e.Default, DialogElementSelectMaxLength))
		if !isMultiSelectDefaultInOptions(e.Default, e.Options) {
			multiErr = multierror.Append(multiErr, errors.Errorf("default value %q contains values not in options", e.Default))
		}
		if e.MultiSelect {
			multiErr = multierror.Append(multiErr, errors.New("multiselect cannot be used with checkbox_group elements"))
		}
		if e.DataSource != "" {
			multiErr = multierror.Append(multiErr, errors.New("checkbox_group elements cannot have a data source"))
		}
		if e.Placeholder != "" {
			multiErr = multierror.Append(multiErr, errors.New("checkbox_group elements cannot have a placeholder"))
		}

	case "checkbox_matrix":
		multiErr = multierror.Append(multiErr, validateDialogElementMatrixConfig(e)...)
		multiErr = multierror.Append(multiErr, checkMaxLength("Default", e.Default, DialogElementSelectMaxLength))
		if e.Default != "" {
			multiErr = multierror.Append(multiErr, validateMatrixDefaultValue(e.Default, e.EffectiveMatrixConfig())...)
		}
		if len(e.Options) > 0 {
			multiErr = multierror.Append(multiErr, errors.New("checkbox_matrix elements cannot have options"))
		}
		if e.MultiSelect {
			multiErr = multierror.Append(multiErr, errors.New("multiselect cannot be used with checkbox_matrix elements"))
		}
		if e.DataSource != "" {
			multiErr = multierror.Append(multiErr, errors.New("checkbox_matrix elements cannot have a data source"))
		}
		if e.Placeholder != "" {
			multiErr = multierror.Append(multiErr, errors.New("checkbox_matrix elements cannot have a placeholder"))
		}

	case "date":
		cfg := e.EffectiveDateTimeConfig()
		multiErr = multierror.Append(multiErr, checkMaxLength("Default", e.Default, DialogElementTextMaxLength))
		multiErr = multierror.Append(multiErr, checkMaxLength("Placeholder", e.Placeholder, DialogElementTextMaxLength))
		multiErr = multierror.Append(multiErr, validateDateFormat(e.Default))
		multiErr = multierror.Append(multiErr, validateDateFormat(cfg.MinDate))
		multiErr = multierror.Append(multiErr, validateDateFormat(cfg.MaxDate))

	case "datetime":
		cfg := e.EffectiveDateTimeConfig()
		multiErr = multierror.Append(multiErr, checkMaxLength("Default", e.Default, DialogElementTextMaxLength))
		multiErr = multierror.Append(multiErr, checkMaxLength("Placeholder", e.Placeholder, DialogElementTextMaxLength))
		multiErr = multierror.Append(multiErr, validateDateTimeFormat(e.Default))
		multiErr = multierror.Append(multiErr, validateDateOrDateTimeFormat(cfg.MinDate))
		multiErr = multierror.Append(multiErr, validateDateOrDateTimeFormat(cfg.MaxDate))
		// Validate time_interval for datetime fields (0 means omitted — treated as default)
		timeInterval := cfg.TimeInterval
		if timeInterval != 0 {
			if timeInterval < 1 || timeInterval > 1440 {
				multiErr = multierror.Append(multiErr, errors.Errorf("time_interval must be between 1 and 1440 minutes, got %d", timeInterval))
			} else if 1440%timeInterval != 0 {
				multiErr = multierror.Append(multiErr, errors.Errorf("time_interval must be a divisor of 1440 (24 hours * 60 minutes) to create valid time intervals, got %d", timeInterval))
			}
		}

	case "collapsible":
		multiErr = multierror.Append(multiErr, e.validateCollapsible(1, seen))

	case "file":
		multiErr = multierror.Append(multiErr, checkMaxLength("Placeholder", e.Placeholder, DialogElementFileMaxLength))
		multiErr = multierror.Append(multiErr, checkMaxLength("Default", e.Default, DialogElementFileMaxLength))
		if e.Default != "" {
			ids := strings.Split(e.Default, ",")
			parsedIds := make([]string, 0, len(ids))
			for _, id := range ids {
				id = strings.TrimSpace(id)
				if id == "" {
					continue
				}
				if !IsValidId(id) {
					multiErr = multierror.Append(multiErr, errors.Errorf("default file ID %q is not a valid ID", id))
					continue
				}
				parsedIds = append(parsedIds, id)
			}
			if !e.AllowMultiple && len(parsedIds) > 1 {
				multiErr = multierror.Append(multiErr, errors.New("default may not contain more than one file ID when allow_multiple is false"))
			}
			if len(parsedIds) > MaxDialogFileIds {
				multiErr = multierror.Append(multiErr, errors.Errorf("default may not contain more than %d file IDs, got %d", MaxDialogFileIds, len(parsedIds)))
			}
		}
		if len(e.Options) > 0 {
			multiErr = multierror.Append(multiErr, errors.New("file elements cannot have options"))
		}
		if e.DataSource != "" {
			multiErr = multierror.Append(multiErr, errors.New("file elements cannot have a data source"))
		}

	case "action_button":
		if e.ActionButton == nil {
			multiErr = multierror.Append(multiErr, errors.New("action_button element requires action_button configuration"))
		} else if e.ActionButton.URL == "" {
			multiErr = multierror.Append(multiErr, errors.New("action_button requires a non-empty URL"))
		} else if !IsValidLookupURL(e.ActionButton.URL) {
			multiErr = multierror.Append(multiErr, errors.Wrap(errors.New("invalid URL"), "invalid action_button URL"))
		}

	default:
		multiErr = multierror.Append(multiErr, errors.Errorf("invalid element type: %q", e.Type))
	}

	return multiErr.ErrorOrNil()
}

// validateCommon runs the field-level checks that apply to every element type,
// independent of any type-specific rules. It is shared by both leaf elements
// (via isValid) and nested collapsible sections (via validateCollapsible) so
// that DisplayName/Name/HelpText, MinLength/MaxLength, and MultiSelect are
// validated for every element in the tree.
func (e *DialogElement) validateCommon() error {
	var multiErr *multierror.Error

	if e.MinLength < 0 {
		multiErr = multierror.Append(multiErr, errors.Errorf("min length cannot be a negative number, got %d", e.MinLength))
	}
	if e.MinLength > e.MaxLength {
		multiErr = multierror.Append(multiErr, errors.Errorf("min length should be less than max length, got %d > %d", e.MinLength, e.MaxLength))
	}

	multiErr = multierror.Append(multiErr, checkMaxLength("DisplayName", e.DisplayName, DialogElementDisplayNameMaxLength))
	multiErr = multierror.Append(multiErr, checkMaxLength("Name", e.Name, DialogElementNameMaxLength))
	multiErr = multierror.Append(multiErr, checkMaxLength("HelpText", e.HelpText, DialogElementHelpTextMaxLength))

	if e.MultiSelect && e.Type != "select" {
		multiErr = multierror.Append(multiErr, errors.Errorf("multiselect can only be used with select elements, got type %q", e.Type))
	}

	return multiErr.ErrorOrNil()
}

// validateCollapsible validates a collapsible element and its children, enforcing
// the maximum nesting depth. depth is the level of this collapsible, where a
// top-level collapsible is depth 1.
func (e *DialogElement) validateCollapsible(depth int, seen map[string]bool) error {
	var multiErr *multierror.Error

	cfg := e.CollapsibleConfig
	if cfg == nil || len(cfg.Elements) == 0 {
		multiErr = multierror.Append(multiErr, errors.New("collapsible element must have at least one child element"))
	}

	var children []DialogElement
	if cfg != nil {
		children = cfg.Elements
	}
	for i, child := range children {
		if seen[child.Name] {
			multiErr = multierror.Append(multiErr, errors.Errorf("duplicate dialog element %q", child.Name))
		}
		seen[child.Name] = true

		if child.Type == "collapsible" {
			// Nested collapsibles are validated directly (rather than via
			// isValid) to preserve depth tracking, so run the common
			// field-level checks here that isValid would otherwise apply.
			if err := child.validateCommon(); err != nil {
				multiErr = multierror.Append(multiErr, errors.Wrapf(err, "%q child element is not valid", child.Name))
			}
			if depth >= DialogCollapsibleMaxDepth {
				multiErr = multierror.Append(multiErr, errors.Errorf("collapsible nesting exceeds maximum depth of %d (child %q at index %d)", DialogCollapsibleMaxDepth, child.Name, i))
				continue
			}
			if err := child.validateCollapsible(depth+1, seen); err != nil {
				multiErr = multierror.Append(multiErr, errors.Wrapf(err, "%q child element is not valid", child.Name))
			}
			continue
		}
		if err := child.isValid(seen); err != nil {
			multiErr = multierror.Append(multiErr, errors.Wrapf(err, "%q child element is not valid", child.Name))
		}
	}

	return multiErr.ErrorOrNil()
}

func isDefaultInOptions(defaultValue string, options []*PostActionOptions) bool {
	if defaultValue == "" {
		return true
	}

	for _, option := range options {
		if option != nil && defaultValue == option.Value {
			return true
		}
	}

	return false
}

func isMultiSelectDefaultInOptions(defaultValue string, options []*PostActionOptions) bool {
	if defaultValue == "" {
		return true
	}

	for value := range strings.SplitSeq(defaultValue, ",") {
		// Trim whitespace around each comma-separated token so defaults like
		// "a, b" match, without stripping spaces inside an option value (e.g.
		// an option whose value is legitimately "high risk").
		value = strings.TrimSpace(value)
		if value == "" {
			continue
		}
		found := false
		for _, option := range options {
			if option != nil && value == option.Value {
				found = true
				break
			}
		}
		if !found {
			return false
		}
	}

	return true
}

func validateDialogElementLabelPosition(e *DialogElement) error {
	if e.LabelPosition == "" {
		return nil
	}
	if e.LabelPosition != DialogLabelPositionBefore && e.LabelPosition != DialogLabelPositionAfter {
		return errors.Errorf("invalid label_position %q, must be %q or %q", e.LabelPosition, DialogLabelPositionBefore, DialogLabelPositionAfter)
	}
	switch e.Type {
	case "bool", "radio", "checkbox_group":
		return nil
	default:
		return errors.Errorf("label_position cannot be used with type %q", e.Type)
	}
}

func validateDialogElementMatrixConfigPlacement(e *DialogElement) error {
	if e.MatrixConfig == nil {
		return nil
	}
	if e.Type != "checkbox_matrix" {
		return errors.Errorf("matrix_config can only be used with checkbox_matrix elements, got type %q", e.Type)
	}
	return nil
}

func validateDialogElementOptions(options []*PostActionOptions, minOptions, maxOptions int, fieldName, disallowedChars string) []error {
	var errs []error
	if len(options) < minOptions {
		errs = append(errs, errors.Errorf("%s must contain at least %d option(s), got %d", fieldName, minOptions, len(options)))
		return errs
	}
	if len(options) > maxOptions {
		errs = append(errs, errors.Errorf("%s may not contain more than %d option(s), got %d", fieldName, maxOptions, len(options)))
	}
	seen := make(map[string]bool, len(options))
	for i, option := range options {
		if option == nil {
			errs = append(errs, errors.Errorf("%s[%d] is nil", fieldName, i))
			continue
		}
		if err := option.IsValid(); err != nil {
			errs = append(errs, errors.Wrapf(err, "%s[%d] is invalid", fieldName, i))
		}
		if disallowedChars != "" && strings.ContainsAny(option.Value, disallowedChars) {
			errs = append(errs, errors.Errorf("%s[%d] value %q must not contain any of %q", fieldName, i, option.Value, disallowedChars))
		}
		if seen[option.Value] {
			errs = append(errs, errors.Errorf("%s[%d] duplicate value %q", fieldName, i, option.Value))
		}
		seen[option.Value] = true
	}
	return errs
}

func validateDialogElementMatrixConfig(e *DialogElement) []error {
	var errs []error
	if e.MatrixConfig == nil {
		errs = append(errs, errors.New("matrix_config is required for checkbox_matrix elements"))
		return errs
	}
	cfg := e.MatrixConfig
	if cfg.RowSelection != "" && cfg.RowSelection != DialogMatrixRowSelectionMultiple && cfg.RowSelection != DialogMatrixRowSelectionSingle {
		errs = append(errs, errors.Errorf("invalid row_selection %q, must be %q or %q", cfg.RowSelection, DialogMatrixRowSelectionMultiple, DialogMatrixRowSelectionSingle))
	}
	// Disallow the three characters used to encode the matrix default value:
	// ";" separates row entries, ":" separates a row from its columns, and ","
	// separates columns. Allowing them in a row/column value would corrupt
	// parsing of the default string in validateMatrixDefaultValue.
	errs = append(errs, validateDialogElementOptions(cfg.Rows, 1, MaxDialogMatrixRows, "matrix_config.rows", ":,;")...)
	errs = append(errs, validateDialogElementOptions(cfg.Columns, 1, MaxDialogMatrixColumns, "matrix_config.columns", ":,;")...)
	return errs
}

// validateMatrixDefaultValue checks that defaultValue is a valid encoded matrix
// selection. The format is semicolon-separated row entries, each of the form
// "rowValue:col1,col2". For example:
//
//	multiple: "row1:colA,colB;row2:colA"
//	single:   "row1:colA;row2:colB"
func validateMatrixDefaultValue(defaultValue string, cfg DialogMatrixConfig) []error {
	var errs []error
	rowValues := make(map[string]bool, len(cfg.Rows))
	for _, row := range cfg.Rows {
		if row != nil {
			rowValues[row.Value] = true
		}
	}
	columnValues := make(map[string]bool, len(cfg.Columns))
	for _, col := range cfg.Columns {
		if col != nil {
			columnValues[col.Value] = true
		}
	}
	seenRows := make(map[string]bool)
	for rowEntry := range strings.SplitSeq(defaultValue, ";") {
		rowEntry = strings.TrimSpace(rowEntry)
		if rowEntry == "" {
			continue
		}
		rowValue, columnsPart, ok := strings.Cut(rowEntry, ":")
		if !ok || rowValue == "" || columnsPart == "" {
			errs = append(errs, errors.Errorf("invalid matrix default entry %q, expected row:col1,col2", rowEntry))
			continue
		}
		if !rowValues[rowValue] {
			errs = append(errs, errors.Errorf("matrix default row %q is not in matrix_config.rows", rowValue))
		}
		if seenRows[rowValue] {
			errs = append(errs, errors.Errorf("duplicate row %q in matrix default", rowValue))
		}
		seenRows[rowValue] = true
		columnCount := 0
		for colValue := range strings.SplitSeq(columnsPart, ",") {
			colValue = strings.TrimSpace(colValue)
			if colValue == "" {
				errs = append(errs, errors.Errorf("invalid empty column in matrix default entry %q", rowEntry))
				continue
			}
			columnCount++
			if !columnValues[colValue] {
				errs = append(errs, errors.Errorf("matrix default column %q is not in matrix_config.columns", colValue))
			}
		}
		if cfg.RowSelection == DialogMatrixRowSelectionSingle && columnCount > 1 {
			errs = append(errs, errors.Errorf("matrix default entry %q has multiple columns but row_selection is single", rowEntry))
		}
	}
	return errs
}

// validateRelativePattern validates relative date patterns like +1d, +2w, +1m, +2H, +30M, +90S
// Case-sensitive: d=days, w=weeks, m=months, H=hours, M=minutes, S=seconds
func validateRelativePattern(value string) bool {
	if len(value) < 3 || len(value) > 5 || (value[0] != '+' && value[0] != '-') {
		return false
	}

	lastChar := value[len(value)-1]
	if !strings.ContainsRune("dwmHMS", rune(lastChar)) {
		return false
	}

	numberPart := value[1 : len(value)-1]
	_, err := strconv.Atoi(numberPart)
	return err == nil
}

// isValidRelativeFormat checks if a string matches relative date patterns
func isValidRelativeFormat(value string) bool {
	relativeFormats := []string{"today", "tomorrow", "yesterday"}
	return slices.Contains(relativeFormats, value) || validateRelativePattern(value)
}

// validateDateFormat validates date strings: ISO date, datetime (with warning), or relative formats
func validateDateFormat(dateStr string) error {
	if dateStr == "" {
		return nil
	}

	if isValidRelativeFormat(dateStr) {
		return nil
	}
	if _, err := time.Parse(ISODateFormat, dateStr); err == nil {
		return nil
	}

	for _, format := range commonDateTimeFormats {
		if parsedTime, err := time.Parse(format, dateStr); err == nil {
			dateOnly := parsedTime.Format(ISODateFormat)
			return fmt.Errorf("date field received datetime format %q, only date portion %q will be used. Consider using date format instead", dateStr, dateOnly)
		}
	}

	return fmt.Errorf("invalid date format: %q, expected ISO format (YYYY-MM-DD), datetime format, or relative format", dateStr)
}

// validateDateTimeFormat validates datetime strings: ISO datetime or relative formats
func validateDateTimeFormat(dateTimeStr string) error {
	if dateTimeStr == "" || isValidRelativeFormat(dateTimeStr) {
		return nil
	}

	for _, format := range commonDateTimeFormats {
		if _, err := time.Parse(format, dateTimeStr); err == nil {
			return nil
		}
	}

	return fmt.Errorf("invalid datetime format: %q, expected ISO format (YYYY-MM-DDTHH:MM:SSZ) or relative format", dateTimeStr)
}

func validateDateOrDateTimeFormat(value string) error {
	dateErr := validateDateFormat(value)
	if dateErr == nil {
		return nil
	}
	dateTimeErr := validateDateTimeFormat(value)
	if dateTimeErr == nil {
		return nil
	}
	return fmt.Errorf("invalid date or datetime format: %q, expected ISO date (YYYY-MM-DD), datetime (YYYY-MM-DDTHH:MM:SSZ), or relative format", value)
}

func checkMaxLength(fieldName string, field string, maxLength int) error {
	// DisplayName and Name are required fields
	if fieldName == "DisplayName" || fieldName == "Name" {
		if len(field) == 0 {
			return errors.Errorf("%v cannot be empty", fieldName)
		}
	}

	if len(field) > maxLength {
		return errors.Errorf("%v cannot be longer than %d characters, got %d", fieldName, maxLength, len(field))
	}

	return nil
}

func (o *Post) StripActionIntegrations() {
	attachments := o.Attachments()
	if o.GetProp(PostPropsAttachments) != nil {
		o.AddProp(PostPropsAttachments, attachments)
	}
	for _, attachment := range attachments {
		for _, action := range attachment.Actions {
			action.Integration = nil
		}
	}
	o.StripMmBlocksActionSecrets()
}

func (o *Post) GetAction(id string) *PostAction {
	for _, attachment := range o.Attachments() {
		for _, action := range attachment.Actions {
			if action != nil && action.Id == id {
				return action
			}
		}
	}
	if spec := o.GetMmBlocksActionSpec(id); spec != nil && spec.Type == MmBlocksActionTypeExternal && spec.URL != "" {
		// Synthesize a PostAction so the existing click pipeline can
		// dispatch without branching on action source. Pre-merge the
		// spec's static per-action query into the URL here; per-click
		// query (from DoPostActionRequest.Query) is merged on top by the
		// caller via MergeQueryIntoURL, with per-click overriding static
		// values on overlapping keys.
		url := spec.URL
		if len(spec.Query) > 0 {
			merged, err := MergeQueryIntoURL(spec.URL, spec.Query)
			if err != nil {
				// Spec URL is malformed. ValidateMmBlocksActions
				// should have rejected it at save time, so this is a
				// belt-and-suspenders guard. Returning nil routes the
				// caller through the standard "action not found"
				// 404 path rather than firing a request to a URL
				// that's missing the static query params.
				return nil
			}
			url = merged
		}
		return &PostAction{
			Id:   id,
			Type: PostActionTypeButton,
			Integration: &PostActionIntegration{
				URL:     url,
				Context: spec.Context,
			},
		}
	}
	return nil
}

var mmBlocksActionIDRegex = regexp.MustCompile(`^[A-Za-z0-9_-]+$`)

// ValidateMmBlocksActions verifies the post's mm_blocks_actions prop has the
// expected shape and bounds. Each entry must coerce to a valid spec via
// mmBlocksEntryMapToSpec.
func ValidateMmBlocksActions(o *Post) error {
	referenced := CollectInteractiveActionIDsFromPost(o)
	raw := o.GetProp(PostPropsMmBlocksActions)
	if raw == nil {
		if len(referenced) > 0 {
			return fmt.Errorf("interactive content requires mm_blocks_actions")
		}
		return nil
	}
	actions, ok := coerceToStringAnyMap(raw)
	if !ok {
		return fmt.Errorf("mm_blocks_actions must be a map")
	}
	if len(actions) > MaxMmBlocksActionsPerPost {
		return fmt.Errorf("mm_blocks_actions exceeds maximum of %d entries", MaxMmBlocksActionsPerPost)
	}
	for key, entry := range actions {
		if len(key) > MaxMmBlocksActionKeyLength {
			return fmt.Errorf("mm_blocks_actions key exceeds %d chars", MaxMmBlocksActionKeyLength)
		}
		if !mmBlocksActionIDRegex.MatchString(key) {
			return fmt.Errorf("mm_blocks_actions key %q must contain only letters, numbers, underscores, or hyphens", key)
		}
		entryMap, ok := coerceToStringAnyMap(entry)
		if !ok {
			return fmt.Errorf("mm_blocks_actions entry %q must be an object", key)
		}
		spec := mmBlocksEntryMapToSpec(entryMap)
		if spec == nil {
			return fmt.Errorf("mm_blocks_actions entry %q has invalid type or shape", key)
		}
		switch spec.Type {
		case MmBlocksActionTypeExternal:
			if err := validateIntegrationURL(spec.URL); err != nil {
				return fmt.Errorf("mm_blocks_actions entry %q: %w", key, err)
			}
			// Bound the per-spec static query so a bot cannot stash
			// unbounded data in the post that gets merged into the
			// outgoing URL on every click.
			if err := ValidateActionQuery(spec.Query); err != nil {
				return fmt.Errorf("mm_blocks_actions entry %q static query: %w", key, err)
			}
			// Bound entry count and key length on the static context.
			// Values are arbitrary JSON, so size is constrained by the
			// outer post-size limit; we cap entries to prevent crafted
			// posts from inflating GetAction's clone cost.
			if len(spec.Context) > MaxActionQueryEntries {
				return fmt.Errorf("mm_blocks_actions entry %q context exceeds maximum of %d entries", key, MaxActionQueryEntries)
			}
			for k := range spec.Context {
				if len(k) > MaxActionQueryKeyLength {
					return fmt.Errorf("mm_blocks_actions entry %q context key exceeds %d chars", key, MaxActionQueryKeyLength)
				}
			}
		case MmBlocksActionTypeOpenURL:
			if err := validateOpenURL(spec.URL); err != nil {
				return fmt.Errorf("mm_blocks_actions entry %q: %w", key, err)
			}
			if err := ValidateActionQuery(spec.Query); err != nil {
				return fmt.Errorf("mm_blocks_actions entry %q static query: %w", key, err)
			}
		}
	}
	return validateMmBlocksActionsPairing(o, actions)
}

// ValidateActionQuery bounds the size of user-supplied per-click query
// parameters so a crafted post cannot trigger unbounded memory use in the
// plugin-request path.
func ValidateActionQuery(q map[string]string) error {
	if len(q) > MaxActionQueryEntries {
		return fmt.Errorf("query exceeds maximum of %d entries", MaxActionQueryEntries)
	}
	for key, value := range q {
		if len(key) > MaxActionQueryKeyLength {
			return fmt.Errorf("query key exceeds %d chars", MaxActionQueryKeyLength)
		}
		if len(value) > MaxActionQueryValueLength {
			return fmt.Errorf("query value for %q exceeds %d chars", key, MaxActionQueryValueLength)
		}
	}
	return nil
}

func validateIntegrationURL(rawURL string) error {
	if rawURL == "" {
		return fmt.Errorf("must have a non-empty URL")
	}
	if !(strings.HasPrefix(rawURL, "/plugins/") || strings.HasPrefix(rawURL, "plugins/") || IsValidHTTPURL(rawURL)) {
		return fmt.Errorf("must have a valid integration URL")
	}
	// Reject path-traversal segments. /plugins/ URLs are routed by the
	// local server, so a `..` segment can escape the plugin namespace and
	// hit unrelated server routes. url.Parse decodes percent-encoded path
	// bytes into u.Path, which is the same single decode pass that
	// doPluginRequest performs at dispatch — so encoded forms like
	// %2e%2e%2f are caught here symmetrically with how the router would
	// resolve them.
	u, parseErr := url.Parse(rawURL)
	if parseErr != nil {
		return fmt.Errorf("must have a valid integration URL: %w", parseErr)
	}
	if pathHasTraversalSegment(u.Path) {
		return fmt.Errorf("integration URL must not contain path traversal segments")
	}
	return nil
}

// validateOpenURL bounds openURL goto targets. Relative paths (/) are used
// for in-app navigation via applyIntegrationGotoLocation; http(s) URLs open in
// a new tab. Plugin integration paths are not allowed here — those belong on
// external actions.
func validateOpenURL(rawURL string) error {
	if rawURL == "" {
		return fmt.Errorf("must have a non-empty URL")
	}
	if strings.HasPrefix(rawURL, "/") {
		if strings.HasPrefix(rawURL, "//") {
			return fmt.Errorf("must not be a protocol-relative URL")
		}
		if strings.HasPrefix(rawURL, "/plugins/") {
			return fmt.Errorf("plugin paths are not allowed for openURL actions")
		}
		u, parseErr := url.Parse(rawURL)
		if parseErr != nil {
			return fmt.Errorf("must have a valid path: %w", parseErr)
		}
		if pathHasTraversalSegment(u.Path) {
			return fmt.Errorf("must not contain path traversal segments")
		}
		return nil
	}
	if !IsValidHTTPURL(rawURL) {
		return fmt.Errorf("must have a valid http or https URL, or a path starting with /")
	}
	return nil
}

func pathHasTraversalSegment(path string) bool {
	return strings.Contains(path, "/../") || strings.HasSuffix(path, "/..") ||
		path == "/.." || strings.HasPrefix(path, "/..")
}

func (o *Post) GenerateActionIds() {
	if o.GetProp(PostPropsAttachments) != nil {
		o.AddProp(PostPropsAttachments, o.Attachments())
	}
	if attachments, ok := o.GetProp(PostPropsAttachments).([]*MessageAttachment); ok {
		for _, attachment := range attachments {
			for _, action := range attachment.Actions {
				if action != nil && action.Id == "" {
					action.Id = NewId()
				}
			}
		}
	}
}

func AddPostActionCookies(o *Post, secret []byte) *Post {
	p := o.Clone()

	// retainedProps carry over their value from the old post, including no value
	retainProps := map[string]any{}
	removeProps := []string{}
	for _, key := range PostActionRetainPropKeys {
		value, ok := p.GetProps()[key]
		if ok {
			retainProps[key] = value
		} else {
			removeProps = append(removeProps, key)
		}
	}

	attachments := p.Attachments()
	for _, attachment := range attachments {
		for _, action := range attachment.Actions {
			c := &PostActionCookie{
				Type:        action.Type,
				ChannelId:   p.ChannelId,
				DataSource:  action.DataSource,
				Integration: action.Integration,
				RetainProps: retainProps,
				RemoveProps: removeProps,
			}

			c.PostId = p.Id
			if p.RootId == "" {
				c.RootPostId = p.Id
			} else {
				c.RootPostId = p.RootId
			}

			b, _ := json.Marshal(c)
			action.Cookie, _ = EncryptPostActionCookie(string(b), secret)
		}
	}

	AddMmBlocksActionCookies(p, secret)

	return p
}

// EncryptPostActionCookie encrypts a plaintext post action cookie payload.
// Exposed for testing.
func EncryptPostActionCookie(plain string, secret []byte) (string, error) {
	if len(secret) == 0 {
		return plain, nil
	}

	block, err := aes.NewCipher(secret)
	if err != nil {
		return "", err
	}

	aesgcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}

	nonce := make([]byte, aesgcm.NonceSize())
	_, err = io.ReadFull(rand.Reader, nonce)
	if err != nil {
		return "", err
	}

	sealed := aesgcm.Seal(nil, nonce, []byte(plain), nil)

	combined := append(nonce, sealed...) //nolint:makezero
	encoded := make([]byte, base64.StdEncoding.EncodedLen(len(combined)))
	base64.StdEncoding.Encode(encoded, combined)

	return string(encoded), nil
}

func DecryptPostActionCookie(encoded string, secret []byte) (string, error) {
	if len(secret) == 0 {
		return encoded, nil
	}

	block, err := aes.NewCipher(secret)
	if err != nil {
		return "", err
	}

	aesgcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}

	decoded := make([]byte, base64.StdEncoding.DecodedLen(len(encoded)))
	n, err := base64.StdEncoding.Decode(decoded, []byte(encoded))
	if err != nil {
		return "", err
	}
	decoded = decoded[:n]

	nonceSize := aesgcm.NonceSize()
	if len(decoded) < nonceSize {
		return "", fmt.Errorf("cookie too short")
	}

	nonce, decoded := decoded[:nonceSize], decoded[nonceSize:]
	plain, err := aesgcm.Open(nil, nonce, decoded, nil)
	if err != nil {
		return "", err
	}

	return string(plain), nil
}

// IsValidLookupURL validates if a URL is safe for lookup operations
func IsValidLookupURL(url string) bool {
	if url == "" {
		return false
	}

	// Allow plugin paths that start with /plugins/
	if strings.HasPrefix(url, "/plugins/") {
		// Additional validation for plugin paths - ensure no path traversal
		if strings.Contains(url, "..") || strings.Contains(url, "//") {
			return false
		}
		return true
	}

	// For external URLs, use the same basic validation as other models
	return IsValidHTTPURL(url)
}