// Copyright 2018 Vector Creations Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package appservice

import (
	"context"
	"errors"
	"net/http"
	"sync"
	"time"

	appserviceAPI "github.com/matrix-org/dendrite/appservice/api"
	"github.com/matrix-org/dendrite/appservice/consumers"
	"github.com/matrix-org/dendrite/appservice/query"
	"github.com/matrix-org/dendrite/appservice/routing"
	"github.com/matrix-org/dendrite/appservice/storage"
	"github.com/matrix-org/dendrite/appservice/types"
	"github.com/matrix-org/dendrite/appservice/workers"
	"github.com/matrix-org/dendrite/clientapi/auth/storage/accounts"
	"github.com/matrix-org/dendrite/clientapi/auth/storage/devices"
	"github.com/matrix-org/dendrite/internal"
	"github.com/matrix-org/dendrite/internal/basecomponent"
	"github.com/matrix-org/dendrite/internal/config"
	"github.com/matrix-org/dendrite/internal/transactions"
	roomserverAPI "github.com/matrix-org/dendrite/roomserver/api"
	"github.com/matrix-org/gomatrixserverlib"
	"github.com/sirupsen/logrus"
)

// SetupAppServiceAPIComponent sets up and registers HTTP handlers for the AppServices
// component.
func SetupAppServiceAPIComponent(
	base *basecomponent.BaseDendrite,
	accountsDB accounts.Database,
	deviceDB devices.Database,
	federation *gomatrixserverlib.FederationClient,
	rsAPI roomserverAPI.RoomserverInternalAPI,
	transactionsCache *transactions.Cache,
) appserviceAPI.AppServiceQueryAPI {
	// Create a connection to the appservice postgres DB
	appserviceDB, err := storage.NewDatabase(string(base.Cfg.Database.AppService), base.Cfg.DbProperties())
	if err != nil {
		logrus.WithError(err).Panicf("failed to connect to appservice db")
	}

	// Wrap application services in a type that relates the application service and
	// a sync.Cond object that can be used to notify workers when there are new
	// events to be sent out.
	workerStates := make([]types.ApplicationServiceWorkerState, len(base.Cfg.Derived.ApplicationServices))
	for i, appservice := range base.Cfg.Derived.ApplicationServices {
		m := sync.Mutex{}
		ws := types.ApplicationServiceWorkerState{
			AppService: appservice,
			Cond:       sync.NewCond(&m),
		}
		workerStates[i] = ws

		// Create bot account for this AS if it doesn't already exist
		if err = generateAppServiceAccount(accountsDB, deviceDB, appservice); err != nil {
			logrus.WithFields(logrus.Fields{
				"appservice": appservice.ID,
			}).WithError(err).Panicf("failed to generate bot account for appservice")
		}
	}

	// Create appserivce query API with an HTTP client that will be used for all
	// outbound and inbound requests (inbound only for the internal API)
	appserviceQueryAPI := query.AppServiceQueryAPI{
		HTTPClient: &http.Client{
			Timeout: time.Second * 30,
		},
		Cfg: base.Cfg,
	}

	appserviceQueryAPI.SetupHTTP(base.InternalAPIMux)

	consumer := consumers.NewOutputRoomEventConsumer(
		base.Cfg, base.KafkaConsumer, accountsDB, appserviceDB,
		rsAPI, workerStates,
	)
	if err := consumer.Start(); err != nil {
		logrus.WithError(err).Panicf("failed to start appservice roomserver consumer")
	}

	// Create application service transaction workers
	if err := workers.SetupTransactionWorkers(appserviceDB, workerStates); err != nil {
		logrus.WithError(err).Panicf("failed to start app service transaction workers")
	}

	// Set up HTTP Endpoints
	routing.Setup(
		base.PublicAPIMux, base.Cfg, rsAPI,
		accountsDB, federation, transactionsCache,
	)

	return &appserviceQueryAPI
}

// generateAppServiceAccounts creates a dummy account based off the
// `sender_localpart` field of each application service if it doesn't
// exist already
func generateAppServiceAccount(
	accountsDB accounts.Database,
	deviceDB devices.Database,
	as config.ApplicationService,
) error {
	ctx := context.Background()

	// Create an account for the application service
	_, err := accountsDB.CreateAccount(ctx, as.SenderLocalpart, "", as.ID)
	if err != nil {
		if errors.Is(err, internal.ErrSQLUserExists) { // This account already exists
			return nil
		}
		return err
	}

	// Create a dummy device with a dummy token for the application service
	_, err = deviceDB.CreateDevice(ctx, as.SenderLocalpart, nil, as.ASToken, &as.SenderLocalpart)
	return err
}