/*******************************************************************************

    ηMatrix - a browser extension to black/white list requests.
    Copyright (C) 2014-2019 The uMatrix/uBlock Origin authors
    Copyright (C) 2019-2020 Alessio Vanni

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see {http://www.gnu.org/licenses/}.

    Home: https://libregit.org/heckyel/ematrix
    uMatrix Home: https://github.com/gorhill/uMatrix
*/

'use strict';

/******************************************************************************/

(function () {
    // API matches that of chrome.storage.local:
    // https://developer.chrome.com/extensions/storage
    vAPI.storage = (function () {
        let db = null;
        let vacuumTimer = null;

        let close = function () {
            if (vacuumTimer !== null) {
                clearTimeout(vacuumTimer);
                vacuumTimer = null;
            }

            if (db === null) {
                return;
            }

            db.asyncClose();
            db = null;
        };

        let open = function () {
            if (db !== null) {
                return db;
            }

            // Create path
            let path = Services.dirsvc.get('ProfD', Ci.nsIFile);
            path.append('ematrix-data');
            if (!path.exists()) {
                path.create(Ci.nsIFile.DIRECTORY_TYPE, parseInt('0774', 8));
            }
            if (!path.isDirectory()) {
                throw Error('Should be a directory...');
            }

            let path2 = Services.dirsvc.get('ProfD', Ci.nsIFile);
            path2.append('extension-data');
            path2.append(location.host + '.sqlite');
            if (path2.exists()) {
                path2.moveTo(path, location.host+'.sqlite');
            }

            path.append(location.host + '.sqlite');

            // Open database
            try {
                db = Services.storage.openDatabase(path);
                if (db.connectionReady === false) {
                    db.asyncClose();
                    db = null;
                }
            } catch (ex) {
                // Ignore
            }

            if (db === null) {
                return null;
            }

            // Database was opened, register cleanup task
            vAPI.addCleanUpTask(close);

            // Setup database
            db.createAsyncStatement('CREATE TABLE IF NOT EXISTS '
                                    +'"settings" ("name" '
                                    +'TEXT PRIMARY KEY NOT NULL, '
                                    +'"value" TEXT);')
                .executeAsync();

            if (vacuum !== null) {
                vacuumTimer = vAPI.setTimeout(vacuum, 60000);
            }

            return db;
        };

        // Vacuum only once, and only while idle
        let vacuum = function () {
            vacuumTimer = null;
            if (db === null) {
                return;
            }
            let idleSvc =
                Cc['@mozilla.org/widget/idleservice;1']
                .getService(Ci.nsIIdleService);

            if (idleSvc.idleTime < 60000) {
                vacuumTimer = vAPI.setTimeout(vacuum, 60000);
                return;
            }

            db.createAsyncStatement('VACUUM').executeAsync();
            vacuum = null;
        };

        // Execute a query
        let runStatement = function (stmt, callback) {
            let result = {};

            stmt.executeAsync({
                handleResult: function (rows) {
                    if (!rows || typeof callback !== 'function') {
                        return;
                    }

                    let row;
                    while ((row = rows.getNextRow())) {
                        // we assume that there will be two columns, since we're
                        // using it only for preferences
                        // eMatrix: the above comment is obsolete
                        // (it's not used just for preferences
                        // anymore), but we still expect two columns.
                        let res = row.getResultByIndex(0);
                        result[res] = row.getResultByIndex(1);
                    }
                },
                handleCompletion: function (reason) {
                    if (typeof callback === 'function' && reason === 0) {
                        callback(result);
                    }
                },
                handleError: function (error) {
                    console.error('SQLite error ', error.result, error.message);

                    // Caller expects an answer regardless of failure.
                    if (typeof callback === 'function' ) {
                        callback(null);
                    }
                },
            });
        };

        let bindNames = function (stmt, names) {
            if (Array.isArray(names) === false || names.length === 0) {
                return;
            }

            let params = stmt.newBindingParamsArray();

            for (let i=names.length-1; i>=0; --i) {
                let bp = params.newBindingParams();
                bp.bindByName('name', names[i]);
                params.addParams(bp);
            }

            stmt.bindParameters(params);
        };

        let clear = function (callback) {
            if (open() === null) {
                if (typeof callback === 'function') {
                    callback();
                }
                return;
            }

            runStatement(db.createAsyncStatement('DELETE FROM "settings";'),
                         callback);
        };

        let getBytesInUse = function (keys, callback) {
            if (typeof callback !== 'function') {
                return;
            }

            if (open() === null) {
                callback(0);
                return;
            }

            let stmt;
            if (Array.isArray(keys)) {
                stmt = db.createAsyncStatement('SELECT "size" AS "size", '
                                               +'SUM(LENGTH("value")) '
                                               +'FROM "settings" WHERE '
                                               +'"name" = :name');
                bindNames(keys);
            } else {
                stmt = db.createAsyncStatement('SELECT "size" AS "size", '
                                               +'SUM(LENGTH("value")) '
                                               +'FROM "settings"');
            }

            runStatement(stmt, function (result) {
                callback(result.size);
            });
        };

        let read = function (details, callback) {
            if (typeof callback !== 'function') {
                return;
            }

            let prepareResult = function (result) {
                for (let key in result) {
                    if (result.hasOwnProperty(key) === false) {
                        continue;
                    }

                    result[key] = JSON.parse(result[key]);
                }

                if (typeof details === 'object' && details !== null) {
                    for (let key in details) {
                        if (result.hasOwnProperty(key) === false) {
                            result[key] = details[key];
                        }
                    }
                }

                callback(result);
            };

            if (open() === null) {
                prepareResult({});
                return;
            }

            let names = [];
            if (details !== null) {
                if (Array.isArray(details)) {
                    names = details;
                } else if (typeof details === 'object') {
                    names = Object.keys(details);
                } else {
                    names = [details.toString()];
                }
            }

            let stmt;
            if (names.length === 0) {
                stmt = db.createAsyncStatement('SELECT * FROM "settings"');
            } else {
                stmt = db.createAsyncStatement('SELECT * FROM "settings" '
                                               +'WHERE "name" = :name');
                bindNames(stmt, names);
            }

            runStatement(stmt, prepareResult);
        };

        let remove = function (keys, callback) {
            if (open() === null) {
                if (typeof callback === 'function') {
                    callback();
                }
                return;
            }

            var stmt = db.createAsyncStatement('DELETE FROM "settings" '
                                               +'WHERE "name" = :name');
            bindNames(stmt, typeof keys === 'string' ? [keys] : keys);
            runStatement(stmt, callback);
        };

        let write = function (details, callback) {
            if (open() === null) {
                if (typeof callback === 'function') {
                    callback();
                }
                return;
            }

            let stmt = db.createAsyncStatement('INSERT OR REPLACE INTO '
                                               +'"settings" ("name", "value") '
                                               +'VALUES(:name, :value)');
            let params = stmt.newBindingParamsArray();

            for (let key in details) {
                if (details.hasOwnProperty(key) === false) {
                    continue;
                }

                let bp = params.newBindingParams();
                bp.bindByName('name', key);
                bp.bindByName('value', JSON.stringify(details[key]));
                params.addParams(bp);
            }

            if (params.length === 0) {
                return;
            }

            stmt.bindParameters(params);
            runStatement(stmt, callback);
        };

        // Export API
        var api = {
            QUOTA_BYTES: 100 * 1024 * 1024,
            clear: clear,
            get: read,
            getBytesInUse: getBytesInUse,
            remove: remove,
            set: write
        };

        return api;
    })();

    vAPI.cacheStorage = vAPI.storage;
})();