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

package api4

import (
	"encoding/json"
	"errors"
	"io"
	"net/http"

	"github.com/mattermost/mattermost/server/public/model"
	"github.com/mattermost/mattermost/server/public/shared/mlog"
)

func (api *API) InitAction() {
	api.BaseRoutes.Post.Handle("/actions/{action_id:[A-Za-z0-9_-]+}", api.APISessionRequired(doPostAction)).Methods(http.MethodPost)

	api.BaseRoutes.APIRoot.Handle("/actions/dialogs/open", api.APIHandler(openDialog)).Methods(http.MethodPost)
	api.BaseRoutes.APIRoot.Handle("/actions/dialogs/submit", api.APISessionRequired(submitDialog)).Methods(http.MethodPost)
	api.BaseRoutes.APIRoot.Handle("/actions/dialogs/lookup", api.APISessionRequired(lookupDialog)).Methods(http.MethodPost)
	api.BaseRoutes.APIRoot.Handle("/actions/dialogs/execute", api.APISessionRequired(executeDialogAction)).Methods(http.MethodPost)
}

func doPostAction(c *Context, w http.ResponseWriter, r *http.Request) {
	c.RequirePostId()
	if c.Err != nil {
		return
	}

	var actionRequest model.DoPostActionRequest
	dec := json.NewDecoder(r.Body)
	err := dec.Decode(&actionRequest)
	if err != nil && !errors.Is(err, io.EOF) {
		// Empty body is allowed for backward-compatibility with older clients.
		// Any other decode failure means the request cannot be trusted — in
		// particular, a wrong-type query would otherwise fall through as nil
		// and silently execute the action without the caller's params.
		c.SetInvalidParamWithErr("action_request", err)
		return
	}
	if err == nil {
		// Reject trailing JSON values after the first object (e.g.
		// `{"query":{"k":"v"}}{"cookie":"x"}`). json.Decoder.Decode
		// stops at the first complete value and would otherwise silently
		// ignore the rest, leaving the caller's intent ambiguous.
		var trailing any
		if extraErr := dec.Decode(&trailing); !errors.Is(extraErr, io.EOF) {
			c.SetInvalidParamWithErr("action_request", extraErr)
			return
		}
	}

	var legacyCookie *model.PostActionCookie
	var mmBlocksCookie *model.MmBlocksActionCookie
	if actionRequest.Cookie != "" {
		cookieStr, decErr := model.DecryptPostActionCookie(actionRequest.Cookie, c.App.PostActionCookieSecret())
		if decErr != nil {
			c.Err = model.NewAppError("DoPostAction", "api.post.do_action.action_integration.app_error", nil, "", http.StatusBadRequest).Wrap(decErr)
			return
		}
		var parseErr error
		legacyCookie, mmBlocksCookie, parseErr = model.ParseDecryptedActionCookiePayload(cookieStr)
		if parseErr != nil {
			c.Err = model.NewAppError("DoPostAction", "api.post.do_action.action_integration.app_error", nil, "", http.StatusBadRequest).Wrap(parseErr)
			return
		}
		if !c.App.Config().FeatureFlags.MmBlocksEnabled && mmBlocksCookie != nil {
			c.Err = model.NewAppError("DoPostAction", "api.post.do_action.action_integration.app_error", nil, "", http.StatusBadRequest).Wrap(errors.New("mm_blocks are not enabled"))
			return
		}

		var cookiePostId string
		var channelID string
		if legacyCookie != nil {
			cookiePostId = legacyCookie.PostId
			channelID = legacyCookie.ChannelId
		} else if mmBlocksCookie != nil {
			cookiePostId = mmBlocksCookie.PostId
			channelID = mmBlocksCookie.ChannelId
		}

		if cookiePostId != c.Params.PostId {
			c.SetPermissionError(model.PermissionReadChannelContent)
			return
		}

		channel, appErr := c.App.GetChannel(c.AppContext, channelID)
		if appErr != nil {
			c.Err = appErr
			return
		}
		if ok, _ := c.App.SessionHasPermissionToReadChannel(c.AppContext, *c.AppContext.Session(), channel); !ok {
			c.SetPermissionError(model.PermissionReadChannelContent)
			return
		}
	} else {
		if ok, _ := c.App.SessionHasPermissionToReadPost(c.AppContext, *c.AppContext.Session(), c.Params.PostId); !ok {
			c.SetPermissionError(model.PermissionReadChannelContent)
			return
		}
	}

	var appErr *model.AppError
	resp := &model.PostActionAPIResponse{Status: "OK"}

	resp.TriggerId, resp.GotoLocation, appErr = c.App.DoPostActionWithCookie(c.AppContext, c.Params.PostId, c.Params.ActionId, c.AppContext.Session().UserId,
		actionRequest.SelectedOption, legacyCookie, mmBlocksCookie, actionRequest.Query, actionRequest.IntegrationFormat)
	if appErr != nil {
		c.Err = appErr
		return
	}

	err = json.NewEncoder(w).Encode(resp)
	if err != nil {
		c.Logger.Warn("Error writing response", mlog.Err(err))
	}
}

func openDialog(c *Context, w http.ResponseWriter, r *http.Request) {
	var dialog model.OpenDialogRequest
	err := json.NewDecoder(r.Body).Decode(&dialog)
	if err != nil {
		c.SetInvalidParamWithErr("dialog", err)
		return
	}

	if dialog.URL == "" {
		c.SetInvalidParam("url")
		return
	}

	if appErr := c.App.OpenInteractiveDialog(c.AppContext, dialog); appErr != nil {
		c.Err = appErr
		return
	}

	ReturnStatusOK(w)
}

func submitDialog(c *Context, w http.ResponseWriter, r *http.Request) {
	var submit model.SubmitDialogRequest

	jsonErr := json.NewDecoder(r.Body).Decode(&submit)
	if jsonErr != nil {
		c.SetInvalidParamWithErr("dialog", jsonErr)
		return
	}

	if submit.URL == "" {
		c.SetInvalidParam("url")
		return
	}

	submit.UserId = c.AppContext.Session().UserId

	channel, err := c.App.GetChannel(c.AppContext, submit.ChannelId)
	if err != nil {
		c.Err = err
		return
	}
	if ok, _ := c.App.SessionHasPermissionToReadChannel(c.AppContext, *c.AppContext.Session(), channel); !ok {
		c.SetPermissionError(model.PermissionReadChannelContent)
		return
	}

	// Derive the team from the server-loaded channel, not the client-supplied
	// TeamId — otherwise a client could omit TeamId on a team channel and skip
	// the PermissionViewTeam check. channel.TeamId is empty for DM/GM channels.
	if channel.TeamId != "" {
		if !c.App.SessionHasPermissionToTeam(*c.AppContext.Session(), channel.TeamId, model.PermissionViewTeam) {
			c.SetPermissionError(model.PermissionViewTeam)
			return
		}
	}

	// The client-supplied TeamId is not trusted for the permission check above, so
	// don't forward it to the integration either — use the channel's authoritative
	// team (empty for DM/GM).
	submit.TeamId = channel.TeamId

	resp, err := c.App.SubmitInteractiveDialog(c.AppContext, submit)
	if err != nil {
		c.Err = err
		return
	}

	b, _ := json.Marshal(resp)

	if _, err := w.Write(b); err != nil {
		c.Logger.Warn("Error while writing response", mlog.Err(err))
	}
}

func executeDialogAction(c *Context, w http.ResponseWriter, r *http.Request) {
	var request model.ExecuteDialogActionRequest

	jsonErr := json.NewDecoder(r.Body).Decode(&request)
	if jsonErr != nil {
		c.SetInvalidParamWithErr("dialog_action", jsonErr)
		return
	}

	if request.URL == "" {
		c.SetInvalidParam("url")
		return
	}

	if !model.IsValidLookupURL(request.URL) {
		c.SetInvalidParam("url")
		return
	}

	channel, err := c.App.GetChannel(c.AppContext, request.ChannelId)
	if err != nil {
		c.Err = err
		return
	}
	if ok, _ := c.App.SessionHasPermissionToReadChannel(c.AppContext, *c.AppContext.Session(), channel); !ok {
		c.SetPermissionError(model.PermissionReadChannelContent)
		return
	}

	// Derive the team from the server-loaded channel, not the client-supplied
	// TeamId — otherwise a client could omit TeamId on a team channel and skip
	// the PermissionViewTeam check. channel.TeamId is empty for DM/GM channels.
	if channel.TeamId != "" {
		if !c.App.SessionHasPermissionToTeam(*c.AppContext.Session(), channel.TeamId, model.PermissionViewTeam) {
			c.SetPermissionError(model.PermissionViewTeam)
			return
		}
	}

	// The client-supplied TeamId is not trusted for the permission check above,
	// so don't trust it for the downstream team lookup / integration payload either.
	// Use the channel's authoritative team (empty for DM/GM, which skips the lookup).
	request.TeamId = channel.TeamId

	triggerId, err := c.App.ExecuteDialogAction(c.AppContext, c.AppContext.Session().UserId, request)
	if err != nil {
		c.Err = err
		return
	}

	resp := &model.ExecuteDialogActionResponse{TriggerId: triggerId}
	if encErr := json.NewEncoder(w).Encode(resp); encErr != nil {
		c.Logger.Warn("Error writing response", mlog.Err(encErr))
	}
}

// lookupDialog handles API requests for dynamic dialog element lookups.
// It validates the request URL for security, checks user permissions, and
// delegates to the app layer for the actual lookup operation.
func lookupDialog(c *Context, w http.ResponseWriter, r *http.Request) {
	var lookup model.SubmitDialogRequest

	jsonErr := json.NewDecoder(r.Body).Decode(&lookup)
	if jsonErr != nil {
		c.SetInvalidParamWithErr("dialog", jsonErr)
		return
	}

	if lookup.URL == "" {
		c.SetInvalidParam("url")
		return
	}

	// Validate URL for security
	if !model.IsValidLookupURL(lookup.URL) {
		c.SetInvalidParam("url")
		return
	}

	lookup.UserId = c.AppContext.Session().UserId

	channel, err := c.App.GetChannel(c.AppContext, lookup.ChannelId)
	if err != nil {
		c.Err = err
		return
	}
	if ok, _ := c.App.SessionHasPermissionToReadChannel(c.AppContext, *c.AppContext.Session(), channel); !ok {
		c.SetPermissionError(model.PermissionReadChannelContent)
		return
	}

	// Derive the team from the server-loaded channel, not the client-supplied
	// TeamId — otherwise a client could omit TeamId on a team channel and skip
	// the PermissionViewTeam check. channel.TeamId is empty for DM/GM channels.
	if channel.TeamId != "" {
		if !c.App.SessionHasPermissionToTeam(*c.AppContext.Session(), channel.TeamId, model.PermissionViewTeam) {
			c.SetPermissionError(model.PermissionViewTeam)
			return
		}
	}

	// The client-supplied TeamId is not trusted for the permission check above, so
	// don't forward it to the integration either — use the channel's authoritative
	// team (empty for DM/GM). Set before logging so the trace reflects the real team.
	lookup.TeamId = channel.TeamId

	c.Logger.Debug("Performing lookup dialog request",
		mlog.String("url", lookup.URL),
		mlog.String("user_id", lookup.UserId),
		mlog.String("channel_id", lookup.ChannelId),
		mlog.String("team_id", lookup.TeamId),
		mlog.Any("selected_field", lookup.Submission["selected_field"]),
		mlog.Any("query", lookup.Submission["query"]),
	)

	resp, err := c.App.LookupInteractiveDialog(c.AppContext, lookup)
	if err != nil {
		c.Logger.Error("Error performing lookup dialog", mlog.Err(err))
		c.Err = err
		return
	}

	b, _ := json.Marshal(resp)

	if _, err := w.Write(b); err != nil {
		c.Logger.Warn("Error while writing response", mlog.Err(err))
	}
}