import {
    DeviceKeyAlgorithm,
    extractRequestError,
    IAppserviceCryptoStorageProvider,
    IAppserviceStorageProvider,
    ICryptoStorageProvider,
    LogService,
    MatrixClient,
    Metrics,
} from "..";
import { Appservice, IAppserviceOptions } from "./Appservice";
// noinspection TypeScriptPreferShortImport
import { timedIntentFunctionCall } from "../metrics/decorators";
import { UnstableAppserviceApis } from "./UnstableAppserviceApis";
import { MatrixError } from "../models/MatrixError";

/**
 * An Intent is an intelligent client that tracks things like the user's membership
 * in rooms to ensure the action being performed is possible. This is very similar
 * to how Intents work in the matrix-js-sdk in that the Intent will ensure that the
 * user is joined to the room before posting a message, for example.
 * @category Application services
 */
export class Intent {
    /**
     * The metrics instance for this intent. Note that this will not raise metrics
     * for the underlying client - those will be available through this instance's
     * parent (the appservice).
     */
    public readonly metrics: Metrics;

    private readonly storage: IAppserviceStorageProvider;
    private readonly cryptoStorage: IAppserviceCryptoStorageProvider;

    private client: MatrixClient;
    private unstableApisInstance: UnstableAppserviceApis;
    private knownJoinedRooms: string[] = [];
    private cryptoSetupPromise: Promise<void>;

    /**
     * Creates a new intent. Intended to be created by application services.
     * @param {IAppserviceOptions} options The options for the application service.
     * @param {string} impersonateUserId The user ID to impersonate.
     * @param {Appservice} appservice The application service itself.
     */
    constructor(private options: IAppserviceOptions, private impersonateUserId: string, private appservice: Appservice) {
        this.metrics = new Metrics(appservice.metrics);
        this.storage = options.storage;
        this.cryptoStorage = options.cryptoStorage;
        this.makeClient(false);
    }

    private makeClient(withCrypto: boolean, accessToken?: string) {
        let cryptoStore: ICryptoStorageProvider;
        const storage = this.storage?.storageForUser?.(this.userId);
        if (withCrypto) {
            cryptoStore = this.cryptoStorage?.storageForUser(this.userId);
            if (!cryptoStore) {
                throw new Error("Tried to set up client with crypto when not available");
            }
            if (!storage) {
                throw new Error("Tried to set up client with crypto, but no persistent storage");
            }
        }
        this.client = new MatrixClient(this.options.homeserverUrl, accessToken ?? this.options.registration.as_token, storage, cryptoStore);
        this.client.metrics = new Metrics(this.appservice.metrics); // Metrics only go up by one parent
        this.unstableApisInstance = new UnstableAppserviceApis(this.client);
        if (this.impersonateUserId !== this.appservice.botUserId) {
            this.client.impersonateUserId(this.impersonateUserId);
        }
        if (this.options.joinStrategy) {
            this.client.setJoinStrategy(this.options.joinStrategy);
        }
    }

    /**
     * Gets the user ID this intent is for.
     */
    public get userId(): string {
        return this.impersonateUserId;
    }

    /**
     * Gets the underlying MatrixClient that powers this Intent.
     */
    public get underlyingClient(): MatrixClient {
        return this.client;
    }

    /**
     * Gets the unstable API access class. This is generally not recommended to be
     * used by appservices.
     * @return {UnstableAppserviceApis} The unstable API access class.
     */
    public get unstableApis(): UnstableAppserviceApis {
        return this.unstableApisInstance;
    }

    /**
     * Sets up crypto on the client if it hasn't already been set up.
     * @returns {Promise<void>} Resolves when complete.
     */
    @timedIntentFunctionCall()
    public async enableEncryption(): Promise<void> {
        if (!this.cryptoSetupPromise) {
            // eslint-disable-next-line no-async-promise-executor
            this.cryptoSetupPromise = new Promise(async (resolve, reject) => {
                try {
                    // Prepare a client first
                    await this.ensureRegistered();
                    const storage = this.storage?.storageForUser?.(this.userId);
                    this.client.impersonateUserId(this.userId); // make sure the devices call works

                    const cryptoStore = this.cryptoStorage?.storageForUser(this.userId);
                    if (!cryptoStore) {
                        // noinspection ExceptionCaughtLocallyJS
                        throw new Error("Failed to create crypto store");
                    }

                    // Try to impersonate a device ID
                    const ownDevices = await this.client.getOwnDevices();
                    let deviceId = await cryptoStore.getDeviceId();
                    if (!deviceId || !ownDevices.some(d => d.device_id === deviceId)) {
                        const deviceKeys = await this.client.getUserDevices([this.userId]);
                        const userDeviceKeys = deviceKeys.device_keys[this.userId];
                        if (userDeviceKeys) {
                            // We really should be validating signatures here, but we're actively looking
                            // for devices without keys to impersonate, so it should be fine. In theory,
                            // those devices won't even be present but we're cautious.
                            const devicesWithKeys = Array.from(Object.entries(userDeviceKeys))
                                .filter(d => d[0] === d[1].device_id && !!d[1].keys?.[`${DeviceKeyAlgorithm.Curve25519}:${d[1].device_id}`]);
                            deviceId = devicesWithKeys[0]?.[1]?.device_id;
                        }
                    }
                    let prepared = false;
                    if (deviceId) {
                        this.makeClient(true);
                        this.client.impersonateUserId(this.userId, deviceId);

                        // verify that the server supports impersonating the device
                        const respDeviceId = (await this.client.getWhoAmI()).device_id;
                        prepared = (respDeviceId === deviceId);
                    }

                    if (!prepared) {
                        // XXX: We work around servers that don't support device_id impersonation
                        const accessToken = await Promise.resolve(storage?.readValue("accessToken"));
                        if (!accessToken) {
                            const loginBody = {
                                type: "m.login.application_service",
                                identifier: {
                                    type: "m.id.user",
                                    user: this.userId,
                                },
                            };
                            this.client.impersonateUserId(null); // avoid confusing homeserver
                            const res = await this.client.doRequest("POST", "/_matrix/client/v3/login", {}, loginBody);
                            this.makeClient(true, res['access_token']);
                            storage.storeValue("accessToken", this.client.accessToken);
                            prepared = true;
                        } else {
                            this.makeClient(true, accessToken);
                            prepared = true;
                        }
                    }

                    if (!prepared) {// noinspection ExceptionCaughtLocallyJS
                        throw new Error("Unable to establish a device ID");
                    }

                    // Now set up crypto
                    await this.client.crypto.prepare(await this.client.getJoinedRooms());

                    this.appservice.on("room.event", (roomId, event) => {
                        if (!this.knownJoinedRooms.includes(roomId)) return;
                        this.client.crypto.onRoomEvent(roomId, event);
                    });

                    resolve();
                } catch (e) {
                    reject(e);
                }
            });
        }
        return this.cryptoSetupPromise;
    }

    /**
     * Gets the joined rooms for the intent. Note that by working around
     * the intent to join rooms may yield inaccurate results.
     * @returns {Promise<string[]>} Resolves to an array of room IDs where
     * the intent is joined.
     */
    @timedIntentFunctionCall()
    public async getJoinedRooms(): Promise<string[]> {
        await this.ensureRegistered();
        if (this.knownJoinedRooms.length === 0) await this.refreshJoinedRooms();
        return this.knownJoinedRooms.map(r => r); // clone
    }

    /**
     * Leaves the given room.
     * @param {string} roomId The room ID to leave
     * @returns {Promise<any>} Resolves when the room has been left.
     */
    @timedIntentFunctionCall()
    public async leaveRoom(roomId: string): Promise<any> {
        await this.ensureRegistered();
        return this.client.leaveRoom(roomId).then(async () => {
            // Recalculate joined rooms now that we've left a room
            await this.refreshJoinedRooms();
        });
    }

    /**
     * Joins the given room
     * @param {string} roomIdOrAlias the room ID or alias to join
     * @returns {Promise<string>} resolves to the joined room ID
     */
    @timedIntentFunctionCall()
    public async joinRoom(roomIdOrAlias: string): Promise<string> {
        await this.ensureRegistered();
        return this.client.joinRoom(roomIdOrAlias).then(async roomId => {
            // Recalculate joined rooms now that we've joined a room
            await this.refreshJoinedRooms();
            return roomId;
        });
    }

    /**
     * Sends a text message to a room.
     * @param {string} roomId The room ID to send text to.
     * @param {string} body The message body to send.
     * @param {"m.text" | "m.emote" | "m.notice"} msgtype The message type to send.
     * @returns {Promise<string>} Resolves to the event ID of the sent message.
     */
    @timedIntentFunctionCall()
    public async sendText(roomId: string, body: string, msgtype: "m.text" | "m.emote" | "m.notice" = "m.text"): Promise<string> {
        return this.sendEvent(roomId, { body: body, msgtype: msgtype });
    }

    /**
     * Sends an event to a room.
     * @param {string} roomId The room ID to send the event to.
     * @param {any} content The content of the event.
     * @returns {Promise<string>} Resolves to the event ID of the sent event.
     */
    @timedIntentFunctionCall()
    public async sendEvent(roomId: string, content: any): Promise<string> {
        await this.ensureRegisteredAndJoined(roomId);
        return this.client.sendMessage(roomId, content);
    }

    /**
     * Ensures the user is registered and joined to the given room.
     * @param {string} roomId The room ID to join
     * @returns {Promise<any>} Resolves when complete
     */
    @timedIntentFunctionCall()
    public async ensureRegisteredAndJoined(roomId: string) {
        await this.ensureRegistered();
        await this.ensureJoined(roomId);
    }

    /**
     * Ensures the user is joined to the given room
     * @param {string} roomId The room ID to join
     * @returns {Promise<any>} Resolves when complete
     */
    @timedIntentFunctionCall()
    public async ensureJoined(roomId: string) {
        if (this.knownJoinedRooms.indexOf(roomId) !== -1) {
            return;
        }

        await this.refreshJoinedRooms();

        if (this.knownJoinedRooms.indexOf(roomId) !== -1) {
            return;
        }

        const returnedRoomId = await this.client.joinRoom(roomId);
        if (!this.knownJoinedRooms.includes(returnedRoomId)) {
            this.knownJoinedRooms.push(returnedRoomId);
        }
        return returnedRoomId;
    }

    /**
     * Refreshes which rooms the user is joined to, potentially saving time on
     * calls like ensureJoined()
     * @returns {Promise<string[]>} Resolves to the joined room IDs for the user.
     */
    @timedIntentFunctionCall()
    public async refreshJoinedRooms(): Promise<string[]> {
        this.knownJoinedRooms = await this.client.getJoinedRooms();
        return this.knownJoinedRooms.map(r => r); // clone
    }

    /**
     * Ensures the user is registered
     * @returns {Promise<any>} Resolves when complete
     */
    @timedIntentFunctionCall()
    public async ensureRegistered() {
        if (!(await Promise.resolve(this.storage.isUserRegistered(this.userId)))) {
            try {
                const result = await this.client.doRequest("POST", "/_matrix/client/v3/register", null, {
                    type: "m.login.application_service",
                    username: this.userId.substring(1).split(":")[0],
                });

                // HACK: Workaround for unit tests
                if (result['errcode']) {
                    // noinspection ExceptionCaughtLocallyJS
                    throw { body: result }; // eslint-disable-line no-throw-literal
                }
            } catch (err) {
                if (err instanceof MatrixError && err.errcode === "M_USER_IN_USE") {
                    await Promise.resolve(this.storage.addRegisteredUser(this.userId));
                    if (this.userId === this.appservice.botUserId) {
                        return null;
                    } else {
                        LogService.error("Appservice", "Error registering user: User ID is in use");
                        return null;
                    }
                } else {
                    LogService.error("Appservice", "Encountered error registering user: ");
                    LogService.error("Appservice", extractRequestError(err));
                }
                throw err;
            }

            await Promise.resolve(this.storage.addRegisteredUser(this.userId));
        }
    }
}
