"use strict";

var utils = require("../../utils");

var DEBUG = false;  // set true to enable console logging.
var E2E_PREFIX = "session.e2e.";

/**
 * Construct a web storage session store, capable of storing account keys,
 * session keys and access tokens.
 * @constructor
 * @param {WebStorage} webStore A web storage implementation, e.g.
 * 'window.localStorage' or 'window.sessionStorage' or a custom implementation.
 * @throws if the supplied 'store' does not meet the Storage interface of the
 * WebStorage API.
 */
function WebStorageSessionStore(webStore) {
    this.store = webStore;
    if (!utils.isFunction(webStore.getItem) ||
        !utils.isFunction(webStore.setItem) ||
        !utils.isFunction(webStore.removeItem)) {
        throw new Error(
            "Supplied webStore does not meet the WebStorage API interface"
        );
    }
}

WebStorageSessionStore.prototype = {

    /**
     * Store the end to end account for the logged-in user.
     * @param {string} account Base64 encoded account.
     */
    storeEndToEndAccount: function(account) {
        this.store.setItem(KEY_END_TO_END_ACCOUNT, account);
    },

    /**
     * Load the end to end account for the logged-in user.
     * @return {?string} Base64 encoded account.
     */
    getEndToEndAccount: function() {
        return this.store.getItem(KEY_END_TO_END_ACCOUNT);
    },

    /**
     * Stores the known devices for a user.
     * @param {string} userId The user's ID.
     * @param {object} devices A map from device ID to keys for the device.
     */
    storeEndToEndDevicesForUser: function(userId, devices) {
        setJsonItem(this.store, keyEndToEndDevicesForUser(userId), devices);
    },

    /**
     * Retrieves the known devices for a user.
     * @param {string} userId The user's ID.
     * @return {object} A map from device ID to keys for the device.
     */
    getEndToEndDevicesForUser: function(userId)  {
        return getJsonItem(this.store, keyEndToEndDevicesForUser(userId));
    },

    /**
     * Store a session between the logged-in user and another device
     * @param {string} deviceKey The public key of the other device.
     * @param {string} sessionId The ID for this end-to-end session.
     * @param {string} session Base64 encoded end-to-end session.
     */
    storeEndToEndSession: function(deviceKey, sessionId, session) {
        var sessions = this.getEndToEndSessions(deviceKey) || {};
        sessions[sessionId] = session;
        setJsonItem(
            this.store, keyEndToEndSessions(deviceKey), sessions
        );
    },

    /**
     * Retrieve the end-to-end sessions between the logged-in user and another
     * device.
     * @param {string} deviceKey The public key of the other device.
     * @return {object} A map from sessionId to Base64 end-to-end session.
     */
    getEndToEndSessions: function(deviceKey) {
        return getJsonItem(this.store, keyEndToEndSessions(deviceKey));
    },

    /**
     * Store the end-to-end state for a room.
     * @param {string} roomId The room's ID.
     * @param {object} roomInfo The end-to-end info for the room.
     */
    storeEndToEndRoom: function(roomId, roomInfo) {
        setJsonItem(this.store, keyEndToEndRoom(roomId), roomInfo);
    },

    /**
     * Get the end-to-end state for a room
     * @param {string} roomId The room's ID.
     * @return {object} The end-to-end info for the room.
     */
    getEndToEndRoom: function(roomId) {
        return getJsonItem(this.store, keyEndToEndRoom(roomId));
    }
};

var KEY_END_TO_END_ACCOUNT = E2E_PREFIX + "account";

function keyEndToEndDevicesForUser(userId) {
    return E2E_PREFIX + "devices/" + userId;
}

function keyEndToEndSessions(deviceKey) {
    return E2E_PREFIX + "sessions/" + deviceKey;
}

function keyEndToEndRoom(roomId) {
    return E2E_PREFIX + "rooms/" + roomId;
}

function getJsonItem(store, key) {
    try {
        return JSON.parse(store.getItem(key));
    }
    catch (e) {
        debuglog("Failed to get key %s: %s", key, e);
        debuglog(e.stack);
    }
    return null;
}

function setJsonItem(store, key, val) {
    store.setItem(key, JSON.stringify(val));
}

function debuglog() {
    if (DEBUG) {
        console.log.apply(console, arguments);
    }
}

/** */
module.exports = WebStorageSessionStore;