// Copyright © 2023 Ory Corp
// SPDX-License-Identifier: Apache-2.0

package check

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"

	"connectrpc.com/connect"
	"github.com/pkg/errors"
	"google.golang.org/protobuf/reflect/protoreflect"

	"github.com/ory/herodot"
	"github.com/ory/x/httprouterx"
	"github.com/ory/x/httpx"
	"github.com/ory/x/logrusx"

	rts "github.com/ory/keto/gen/go/ory/keto/relation_tuples/v1alpha2"
	"github.com/ory/keto/gen/go/ory/keto/relation_tuples/v1alpha2/relationtuplesconnect"
	"github.com/ory/keto/internal/driver/config"
	"github.com/ory/keto/internal/relationtuple"
	"github.com/ory/keto/internal/x"
	"github.com/ory/keto/ketoapi"
)

type (
	handlerDependencies interface {
		EngineProvider
		relationtuple.ManagerProvider
		relationtuple.MapperProvider
		logrusx.Provider
		httpx.WriterProvider
		config.Provider
		x.HandlerOptionsProvider
	}
	Handler struct {
		relationtuplesconnect.UnimplementedCheckServiceHandler
		d handlerDependencies
	}
)

var (
	_ relationtuplesconnect.CheckServiceHandler = (*Handler)(nil)
	_ *checkPermission                          = nil
)

func NewHandler(d handlerDependencies) *Handler { return &Handler{d: d} }

const (
	RouteBase        = "/relation-tuples/check"
	OpenAPIRouteBase = RouteBase + "/openapi"
	BatchRoute       = "/relation-tuples/batch/check"
)

func (h *Handler) RegisterReadRoutes(r *httprouterx.RouterPublic) {
	r.GET(RouteBase, h.getCheckMirrorStatus)
	r.GET(OpenAPIRouteBase, h.getCheckNoStatus)
	r.POST(RouteBase, h.postCheckMirrorStatus)
	r.POST(OpenAPIRouteBase, h.postCheckNoStatus)
	r.POST(BatchRoute, h.batchCheck)

	checkServiceMethods := rts.File_ory_keto_relation_tuples_v1alpha2_check_service_proto.Services().ByName("CheckService").Methods()

	checkHandler := connect.NewUnaryHandler(
		relationtuplesconnect.CheckServiceCheckProcedure,
		h.Check,
		connect.WithSchema(checkServiceMethods.ByName("Check")),
		connect.WithHandlerOptions(h.d.HandlerOptions()...),
	)
	r.Handle(relationtuplesconnect.CheckServiceCheckProcedure, checkHandler)

	batchCheckHandler := connect.NewUnaryHandler(
		relationtuplesconnect.CheckServiceBatchCheckProcedure,
		h.BatchCheck,
		connect.WithSchema(checkServiceMethods.ByName("BatchCheck")),
		connect.WithHandlerOptions(h.d.HandlerOptions()...),
	)
	r.Handle(relationtuplesconnect.CheckServiceBatchCheckProcedure, batchCheckHandler)
}

func (h *Handler) ProtoFiles() []protoreflect.FileDescriptor {
	return []protoreflect.FileDescriptor{
		rts.File_ory_keto_relation_tuples_v1alpha2_check_service_proto,
		rts.File_ory_keto_relation_tuples_v1alpha2_relation_tuples_proto,
	}
}

// Check Permission Result
//
// The content of the allowed field is mirrored in the HTTP status code.
//
// swagger:model checkPermissionResult
type CheckPermissionResult struct {
	// whether the relation tuple is allowed
	//
	// required: true
	Allowed bool `json:"allowed"`
}

// Check Permission Result With Error
//
// swagger:model checkPermissionResultWithError
type CheckPermissionResultWithError struct {
	// whether the relation tuple is allowed
	//
	// required: true
	Allowed bool `json:"allowed"`
	// any error generated while checking the relation tuple
	//
	// required: false
	Error string `json:"error,omitempty"`
}

// Check Permission Request Parameters
//
// swagger:parameters checkPermission
type checkPermission struct {
	// in: query
	MaxDepth int `json:"max-depth"`
}

// swagger:route GET /relation-tuples/check/openapi permission checkPermission
//
// # Check a permission
//
// To learn how relationship tuples and the check works, head over to [the documentation](https://www.ory.com/docs/keto/concepts/api-overview).
//
//	Consumes:
//	-  application/x-www-form-urlencoded
//
//	Produces:
//	- application/json
//
//	Schemes: http, https
//
//	Responses:
//	  200: checkPermissionResult
//	  400: errorGeneric
//	  default: errorGeneric
//
//	Extensions:
//	  x-ory-ratelimit-bucket: keto-public-high
func (h *Handler) getCheckNoStatus(w http.ResponseWriter, r *http.Request) {
	allowed, err := h.getCheck(r.Context(), r.URL.Query())
	if err != nil {
		h.d.Writer().WriteError(w, r, err)
		return
	}
	h.d.Writer().Write(w, r, &CheckPermissionResult{Allowed: allowed})
}

// Check Permission Or Error Request Parameters
//
// swagger:parameters checkPermissionOrError
//
//lint:ignore U1000 Used to generate Swagger and OpenAPI definitions
type checkPermissionOrError struct {
	// in: query
	MaxDepth int `json:"max-depth"`
}

// swagger:route GET /relation-tuples/check permission checkPermissionOrError
//
// # Check a permission
//
// To learn how relationship tuples and the check works, head over to [the documentation](https://www.ory.com/docs/keto/concepts/api-overview).
//
//	Consumes:
//	-  application/x-www-form-urlencoded
//
//	Produces:
//	- application/json
//
//	Schemes: http, https
//
//	Responses:
//	  200: checkPermissionResult
//	  400: errorGeneric
//	  403: checkPermissionResult
//	  default: errorGeneric
//
//	Extensions:
//	  x-ory-ratelimit-bucket: keto-public-high
func (h *Handler) getCheckMirrorStatus(w http.ResponseWriter, r *http.Request) {
	allowed, err := h.getCheck(r.Context(), r.URL.Query())
	if err != nil {
		h.d.Writer().WriteError(w, r, err)
		return
	}

	if allowed {
		h.d.Writer().Write(w, r, &CheckPermissionResult{Allowed: allowed})
		return
	}

	h.d.Writer().WriteCode(w, r, http.StatusForbidden, &CheckPermissionResult{Allowed: allowed})
}

func (h *Handler) getCheck(ctx context.Context, q url.Values) (bool, error) {
	maxDepth, err := x.GetMaxDepthFromQuery(q)
	if err != nil {
		return false, err
	}

	tuple, err := (&ketoapi.RelationTuple{}).FromURLQuery(q)
	if err != nil {
		return false, err
	}

	it, err := h.d.ReadOnlyMapper().FromTuple(ctx, tuple)
	// herodot.ErrNotFound occurs when the namespace is unknown
	if errors.Is(err, herodot.ErrNotFound()) {
		return false, nil
	} else if err != nil {
		return false, err
	}

	return h.d.PermissionEngine().CheckIsMember(ctx, it[0], maxDepth)
}

// Check Permission using Post Request Parameters
//
// swagger:parameters postCheckPermission
//
//lint:ignore U1000 Used to generate Swagger and OpenAPI definitions
type postCheckPermission struct {
	// in: query
	MaxDepth int `json:"max-depth"`

	// in: body
	Payload postCheckPermissionBody
}

// Check Permission using Post Request Body
//
// swagger:model postCheckPermissionBody
//
//lint:ignore U1000 Used to generate Swagger and OpenAPI definitions
type postCheckPermissionBody struct {
	ketoapi.RelationQuery
}

// swagger:route POST /relation-tuples/check/openapi permission postCheckPermission
//
// # Check a permission
//
// To learn how relationship tuples and the check works, head over to [the documentation](https://www.ory.com/docs/keto/concepts/api-overview).
//
//	Consumes:
//	-  application/json
//
//	Produces:
//	- application/json
//
//	Schemes: http, https
//
//	Responses:
//	  200: checkPermissionResult
//	  400: errorGeneric
//	  default: errorGeneric
//
//	Extensions:
//	  x-ory-ratelimit-bucket: keto-public-high
func (h *Handler) postCheckNoStatus(w http.ResponseWriter, r *http.Request) {
	allowed, err := h.postCheck(r.Context(), r.Body, r.URL.Query())
	if err != nil {
		h.d.Writer().WriteError(w, r, err)
		return
	}
	h.d.Writer().Write(w, r, &CheckPermissionResult{Allowed: allowed})
}

// Post Check Permission Or Error Request Parameters
//
// swagger:parameters postCheckPermissionOrError
//
//lint:ignore U1000 Used to generate Swagger and OpenAPI definitions
type postCheckPermissionOrError struct {
	// in: query
	MaxDepth int `json:"max-depth"`

	// in: body
	Body postCheckPermissionOrErrorBody
}

// Post Check Permission Or Error Body
//
// swagger:model postCheckPermissionOrErrorBody
//
//lint:ignore U1000 Used to generate Swagger and OpenAPI definitions
type postCheckPermissionOrErrorBody struct {
	ketoapi.RelationQuery
}

// swagger:route POST /relation-tuples/check permission postCheckPermissionOrError
//
// # Check a permission
//
// To learn how relationship tuples and the check works, head over to [the documentation](https://www.ory.com/docs/keto/concepts/api-overview).
//
//	Consumes:
//	-  application/json
//
//	Produces:
//	- application/json
//
//	Schemes: http, https
//
//	Responses:
//	  200: checkPermissionResult
//	  400: errorGeneric
//	  403: checkPermissionResult
//	  default: errorGeneric
//
//	Extensions:
//	  x-ory-ratelimit-bucket: keto-public-high
func (h *Handler) postCheckMirrorStatus(w http.ResponseWriter, r *http.Request) {
	allowed, err := h.postCheck(r.Context(), r.Body, r.URL.Query())
	if err != nil {
		h.d.Writer().WriteError(w, r, err)
		return
	}

	if allowed {
		h.d.Writer().Write(w, r, &CheckPermissionResult{Allowed: allowed})
		return
	}

	h.d.Writer().WriteCode(w, r, http.StatusForbidden, &CheckPermissionResult{Allowed: allowed})
}

func (h *Handler) postCheck(ctx context.Context, body io.Reader, query url.Values) (bool, error) {
	maxDepth, err := x.GetMaxDepthFromQuery(query)
	if err != nil {
		return false, err
	}

	var tuple ketoapi.RelationTuple
	if err := json.NewDecoder(body).Decode(&tuple); err != nil {
		return false, errors.WithStack(herodot.ErrBadRequest().WithErrorf("could not unmarshal json: %s", err.Error()))
	}
	t, err := h.d.ReadOnlyMapper().FromTuple(ctx, &tuple)
	// herodot.ErrNotFound occurs when the namespace is unknown
	if errors.Is(err, herodot.ErrNotFound()) {
		return false, nil
	} else if err != nil {
		return false, err
	}

	return h.d.PermissionEngine().CheckIsMember(ctx, t[0], maxDepth)
}

func (h *Handler) Check(ctx context.Context, req *connect.Request[rts.CheckRequest]) (*connect.Response[rts.CheckResponse], error) {
	var src ketoapi.TupleData
	if req.Msg.Tuple != nil {
		src = req.Msg.Tuple
	} else {
		src = req.Msg
	}

	tuple, err := (&ketoapi.RelationTuple{}).FromDataProvider(src)
	if err != nil {
		return nil, err
	}

	internalTuple, err := h.d.ReadOnlyMapper().FromTuple(ctx, tuple)
	if err != nil {
		return nil, err
	}
	allowed, err := h.d.PermissionEngine().CheckIsMember(ctx, internalTuple[0], int(req.Msg.MaxDepth))
	// TODO add content change handling
	if err != nil {
		return nil, err
	}

	return connect.NewResponse(&rts.CheckResponse{ //nolint:gosec // Snaptoken is not a credential, just a placeholder value.
		Allowed:   allowed,
		Snaptoken: "not yet implemented",
	}), nil
}

// Batch Check Permission Request Parameters
//
// swagger:parameters batchCheckPermission
//
//lint:ignore U1000 Used to generate Swagger and OpenAPI definitions
type batchCheckPermission struct {
	// in: query
	MaxDepth int `json:"max-depth"`

	// in: body
	Body batchCheckPermissionBody
}

// Batch Check Permission Body
//
// swagger:model batchCheckPermissionBody
//
//lint:ignore U1000 Used to generate Swagger and OpenAPI definitions
type batchCheckPermissionBody struct {
	Tuples []*ketoapi.RelationTuple `json:"tuples"`
}

// Batch Check Permission Result
//
// swagger:model batchCheckPermissionResult
type BatchCheckPermissionResult struct {
	// An array of check results. The order aligns with the input order.
	//
	// required: true
	Results []*CheckPermissionResultWithError `json:"results"`
}

// swagger:route POST /relation-tuples/batch/check permission batchCheckPermission
//
// # Batch check permissions
//
// To learn how relationship tuples and the check works, head over to [the documentation](https://www.ory.com/docs/keto/concepts/api-overview).
//
//	Consumes:
//	-  application/json
//
//	Produces:
//	- application/json
//
//	Schemes: http, https
//
//	Responses:
//	  200: batchCheckPermissionResult
//	  400: errorGeneric
//	  default: errorGeneric
//
//	Extensions:
//	  x-ory-ratelimit-bucket: keto-public-high
func (h *Handler) batchCheck(w http.ResponseWriter, r *http.Request) {
	results, err := h.doBatchCheck(r.Context(), r.Body, r.URL.Query())
	if err != nil {
		h.d.Writer().WriteError(w, r, err)
		return
	}

	h.d.Writer().Write(w, r, &BatchCheckPermissionResult{Results: results})
}

// doBatchCheck is the HTTP entry point for checking batches of tuples
func (h *Handler) doBatchCheck(ctx context.Context, body io.Reader, query url.Values) ([]*CheckPermissionResultWithError, error) {
	maxDepth, err := x.GetMaxDepthFromQuery(query)
	if err != nil {
		return nil, err
	}
	var request batchCheckPermissionBody
	if err := json.NewDecoder(body).Decode(&request); err != nil {
		return nil, errors.WithStack(herodot.ErrBadRequest().WithErrorf("could not unmarshal json: %s", err.Error()))
	}

	if len(request.Tuples) > h.d.Config(ctx).BatchCheckMaxBatchSize() {
		return nil, herodot.ErrBadRequest().WithErrorf("batch exceeds max size of %v",
			h.d.Config(ctx).BatchCheckMaxBatchSize())
	}

	results, err := h.d.PermissionEngine().BatchCheck(ctx, request.Tuples, maxDepth)
	if err != nil {
		return nil, err
	}

	strict := h.d.Config(ctx).StrictMode()
	responses := make([]*CheckPermissionResultWithError, len(request.Tuples))
	for i, result := range results {
		responses[i] = &CheckPermissionResultWithError{
			Allowed: result.Membership == IsMember,
			Error:   batchResultErrMsg(result, strict),
		}
	}

	return responses, nil
}

// BatchCheck is the gRPC entry point for checking batches of tuples
func (h *Handler) BatchCheck(ctx context.Context, req *connect.Request[rts.BatchCheckRequest]) (*connect.Response[rts.BatchCheckResponse], error) {
	if len(req.Msg.Tuples) > h.d.Config(ctx).BatchCheckMaxBatchSize() {
		return nil, connect.NewError(connect.CodeInvalidArgument, fmt.Errorf(
			"batch exceeds max size of %v", h.d.Config(ctx).BatchCheckMaxBatchSize()))
	}

	ketoTuples := make([]*ketoapi.RelationTuple, len(req.Msg.Tuples))
	for i, tuple := range req.Msg.Tuples {
		ketoTuples[i] = (&ketoapi.RelationTuple{}).FromProto(tuple)
	}

	results, err := h.d.PermissionEngine().BatchCheck(ctx, ketoTuples, int(req.Msg.MaxDepth))
	if err != nil {
		return nil, err
	}

	strict := h.d.Config(ctx).StrictMode()
	responses := make([]*rts.CheckResponseWithError, len(results))
	for i, result := range results {
		responses[i] = &rts.CheckResponseWithError{ //nolint:gosec // Snaptoken is not a credential, just a placeholder value.
			Allowed:   result.Membership == IsMember,
			Error:     batchResultErrMsg(result, strict),
			Snaptoken: "not yet implemented",
		}
	}

	return connect.NewResponse(&rts.BatchCheckResponse{
		Results: responses,
	}), nil
}

// batchResultErrMsg returns an error string for a single batch check result.
// In strict mode a limitation is surfaced so callers can distinguish
// "definitely not a member" from "could not determine membership".
func batchResultErrMsg(r Result, strict bool) string {
	if r.Err != nil {
		return r.Err.Error()
	}
	if r.Membership == MembershipUnknown && r.Limitation != "" && strict {
		return string(r.Limitation)
	}
	return ""
}