package matrix

import (
	"context"
	"database/sql"
	"log"
	"sync"

	"maunium.net/go/mautrix"
	"maunium.net/go/mautrix/crypto"
	"maunium.net/go/mautrix/event"
	"maunium.net/go/mautrix/id"
)

type Client struct {
	client		*mautrix.Client
	config		*Config
	db		*sql.DB
	greetedRooms	[]id.RoomID
	olmMachine	*crypto.OlmMachine
	store		*sqlStore
	syncer		*mautrix.DefaultSyncer
}

type Config struct {
	AllowedRooms	[]string	`json:"allowed_rooms"`
	DeviceName	string		`json:"device_name"`
	Greeting	string
	LogLevel	uint		`json:"log_level"`
	HomeserverURL	string		`json:"homeserver_url"`
	UserIdentifier	string		`json:"user_identifier"`
	Password	string
	PickleKey	string		`json:"pickle_key"`
}

func NewClient(config *Config, db *sql.DB) (*Client, error) {
	client, err := mautrix.NewClient(config.HomeserverURL, "", "")
	if err != nil {
		return nil, err
	}

	syncer := mautrix.NewDefaultSyncer()
	client.Syncer = syncer

	store := &sqlStore{db}
	client.Store = store

	err = store.CreateTables()
	if err != nil {
		return nil, err
	}

	c := &Client{
		client:		client,
		config:		config,
		db:		db,
		store:		store,
		syncer:		syncer,
	}

	syncer.OnEventType(event.StateMember, c.handleMemberEvent)

	return c, nil
}

func (c *Client) Login() error {
	userID, err := makeUserID(c.config.UserIdentifier, c.config.HomeserverURL)
	if err != nil {
		return err
	}

	deviceID := c.loadDeviceID(userID)

	_, err = c.client.Login(&mautrix.ReqLogin{
		Type:				mautrix.AuthTypePassword,
		Identifier:			mautrix.UserIdentifier{
			Type:	mautrix.IdentifierTypeUser,
			User:	c.config.UserIdentifier,
		},
		Password:			c.config.Password,
		DeviceID:			deviceID,
		InitialDeviceDisplayName:	c.config.DeviceName,
		StoreCredentials:		true,
	})
	if err != nil {
		return err
	}

	log.Print("device ID: ", c.client.DeviceID)

	return nil
}

func (c *Client) Encrypt() error {
	sqlCryptoStore := crypto.NewSQLCryptoStore(
		c.db,
		"sqlite3",
		c.client.UserID.String(),
		c.client.DeviceID,
		[]byte(c.config.PickleKey),
		logger{
			Level: c.config.LogLevel,
		},
	)

	err := sqlCryptoStore.CreateTables()
	if err != nil {
		return err
	}

	c.olmMachine = crypto.NewOlmMachine(c.client, &logger{
		Level: c.config.LogLevel,
	}, sqlCryptoStore, c.store)

	err = c.olmMachine.Load()
	if err != nil {
		return err
	}

	c.syncer.OnSync(c.olmMachine.ProcessSyncResponse)

	c.syncer.OnEventType(event.StateEncryption, c.handleEncryptionEvent)

	return nil
}

func (c *Client) Sync(ctx context.Context, cancel context.CancelFunc, wg *sync.WaitGroup) {
	wg.Add(1)
	defer wg.Done()

	for {
		select {
		case <-ctx.Done():
			return
		default:
			err := c.client.SyncWithContext(ctx)
			if err != nil && err != ctx.Err() {
				log.Print(err)
				cancel()
			}
		}
	}
}

func (c *Client) Send(roomID id.RoomID, message *event.MessageEventContent) error {
	content := event.Content{Parsed: message}

	if c.store.IsEncrypted(roomID) {
		encrypted, err := c.olmMachine.EncryptMegolmEvent(roomID, event.EventMessage, &content)
		if err == crypto.NoGroupSession || err == crypto.SessionExpired || err == crypto.SessionNotShared {
			err = c.olmMachine.ShareGroupSession(roomID, c.store.GetRoomMembers(roomID))
			if err != nil {
				return err
			}

			encrypted, err = c.olmMachine.EncryptMegolmEvent(roomID, event.EventMessage, &content)
		}

		if err != nil {
			return err
		}

		_, err = c.client.SendMessageEvent(roomID, event.EventEncrypted, encrypted)
		if err != nil {
			return err
		}
	} else {
		_, err := c.client.SendMessageEvent(roomID, event.EventMessage, &content)
		if err != nil {
			return err
		}
	}

	return nil
}

func (c *Client) Broadcast(message *event.MessageEventContent) (success bool) {
	for _, roomID := range c.store.FindAllSharedRooms(c.client.UserID) {
		allowed := false
		for _, room := range c.config.AllowedRooms {
			if room == roomID.String() {
				allowed = true
				break
			}
		}

		if !allowed {
			continue
		}

		err := c.Send(roomID, message)
		if err != nil {
			log.Print(err)
		} else {
			success = true
		}
	}

	return success
}

func (c *Client) handleMemberEvent(source mautrix.EventSource, evt *event.Event) {
	if c.olmMachine != nil {
		c.olmMachine.HandleMemberEvent(evt)
	}

	c.store.SetMembership(evt.RoomID, evt.GetStateKey(), evt.Content.AsMember().Membership)

	if evt.GetStateKey() == c.client.UserID.String() && evt.Content.AsMember().Membership == event.MembershipInvite {
		allowed := false
		for _, room := range c.config.AllowedRooms {
			if room == evt.RoomID.String() {
				allowed = true
				break
			}
		}

		if allowed {
			_, err := c.client.JoinRoomByID(evt.RoomID)
			if err != nil {
				log.Print(err)
			}

			for _, room := range c.greetedRooms {
				if room == evt.RoomID {
					return
				}
			}

			message := event.MessageEventContent{
				MsgType:	event.MsgText,
				Body:		c.config.Greeting,
			}

			err = c.Send(evt.RoomID, &message)
			if err != nil {
				log.Print(err)
				return
			}

			c.greetedRooms = append(c.greetedRooms, evt.RoomID)
		} else {
			_, err := c.client.LeaveRoom(evt.RoomID)
			if err != nil {
				log.Print(err)
			}
		}
	}
}

func (c *Client) handleEncryptionEvent(source mautrix.EventSource, evt *event.Event) {
	c.store.SetEncryptionEvent(evt.RoomID, evt.Content.AsEncryption())
}

func (c *Client) loadDeviceID(accountID id.UserID) (deviceID id.DeviceID) {
	row := c.db.QueryRow("SELECT device_id FROM crypto_account WHERE account_id = ?;", accountID)

	err := row.Scan(&deviceID)
	if err != nil {
		return ""
	}

	return deviceID
}