/*
Copyright 2019 New Vector 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.
*/

import Matrix from 'matrix-js-sdk';
import LocalStorageCryptoStore from 'matrix-js-sdk/lib/crypto/store/localStorage-crypto-store';
import Analytics from '../Analytics';

const localStorage = window.localStorage;

// just *accessing* indexedDB throws an exception in firefox with
// indexeddb disabled.
let indexedDB;
try {
    indexedDB = window.indexedDB;
} catch (e) {}

// The JS SDK will add a prefix of "matrix-js-sdk:" to the sync store name.
const SYNC_STORE_NAME = "riot-web-sync";
const CRYPTO_STORE_NAME = "matrix-js-sdk:crypto";

function log(msg) {
    console.log(`StorageManager: ${msg}`);
}

function error(msg) {
    console.error(`StorageManager: ${msg}`);
}

function track(action) {
    Analytics.trackEvent("StorageManager", action);
}

export async function checkConsistency() {
    log("Checking storage consistency");
    log(`Local storage supported? ${!!localStorage}`);
    log(`IndexedDB supported? ${!!indexedDB}`);

    let dataInLocalStorage = false;
    let dataInCryptoStore = false;
    let healthy = true;

    if (localStorage) {
        dataInLocalStorage = localStorage.length > 0;
        log(`Local storage contains data? ${dataInLocalStorage}`);
    } else {
        healthy = false;
        error("Local storage cannot be used on this browser");
        track("Local storage disabled");
    }

    if (indexedDB && localStorage) {
        const results = await checkSyncStore();
        if (!results.healthy) {
            healthy = false;
        }
    } else {
        healthy = false;
        error("Sync store cannot be used on this browser");
        track("Sync store disabled");
    }

    if (indexedDB) {
        const results = await checkCryptoStore();
        dataInCryptoStore = results.exists;
        if (!results.healthy) {
            healthy = false;
        }
    } else {
        healthy = false;
        error("Crypto store cannot be used on this browser");
        track("Crypto store disabled");
    }

    if (dataInLocalStorage && !dataInCryptoStore) {
        healthy = false;
        error(
            "Data exists in local storage but not in crypto store. " +
            "IndexedDB storage has likely been evicted by the browser!",
        );
        track("Crypto store evicted");
    }

    if (healthy) {
        log("Storage consistency checks passed");
        track("Consistency checks passed");
    } else {
        error("Storage consistency checks failed");
        track("Consistency checks failed");
    }

    return {
        dataInLocalStorage,
        dataInCryptoStore,
        healthy,
    };
}

async function checkSyncStore() {
    let exists = false;
    try {
        exists = await Matrix.IndexedDBStore.exists(
            indexedDB, SYNC_STORE_NAME,
        );
        log(`Sync store using IndexedDB contains data? ${exists}`);
        return { exists, healthy: true };
    } catch (e) {
        error("Sync store using IndexedDB inaccessible", e);
        track("Sync store using IndexedDB inaccessible");
    }
    log("Sync store using memory only");
    return { exists, healthy: false };
}

async function checkCryptoStore() {
    let exists = false;
    try {
        exists = await Matrix.IndexedDBCryptoStore.exists(
            indexedDB, CRYPTO_STORE_NAME,
        );
        log(`Crypto store using IndexedDB contains data? ${exists}`);
        return { exists, healthy: true };
    } catch (e) {
        error("Crypto store using IndexedDB inaccessible", e);
        track("Crypto store using IndexedDB inaccessible");
    }
    try {
        exists = await LocalStorageCryptoStore.exists(localStorage);
        log(`Crypto store using local storage contains data? ${exists}`);
        return { exists, healthy: true };
    } catch (e) {
        error("Crypto store using local storage inaccessible", e);
        track("Crypto store using local storage inaccessible");
    }
    log("Crypto store using memory only");
    return { exists, healthy: false };
}