var safeRequire = require('../utils').safeRequire;

/**
 * Module dependencies
 */
var redis = safeRequire('redis');

exports.initialize = function initializeSchema(schema, callback) {
    if (!redis) return;

    if (schema.settings.url) {
        var url = require('url');
        var redisUrl = url.parse(schema.settings.url);
        var redisAuth = (redisUrl.auth || '').split(':');
        schema.settings.host = redisUrl.hostname;
        schema.settings.port = redisUrl.port;

        if (redisAuth.length == 2) {
            schema.settings.db = redisAuth[0];
            schema.settings.password = redisAuth[1];
        }
    }

    schema.client = redis.createClient(
        schema.settings.port,
        schema.settings.host,
        schema.settings.options
    );
    schema.client.auth(schema.settings.password);
    var callbackCalled = false;
    var database = schema.settings.hasOwnProperty('database') && schema.settings.database;
    schema.client.on('connect', function () {
        if (!callbackCalled && database === false) {
            callbackCalled = true;
            callback();
        } else if (database !== false) {
            if (callbackCalled) {
                return schema.client.select(schema.settings.database);
            } else {
                callbackCalled = true;
                return schema.client.select(schema.settings.database, callback);
            }
        }
    });

    var clientWrapper = new Client(schema.client);

    schema.adapter = new BridgeToRedis(clientWrapper);
    clientWrapper._adapter = schema.adapter;
};

function Client(client) {
    this._client = client;
}

var commands = Object.keys(redis.Multi.prototype).filter(function (n) {
    return n.match(/^[a-z]/);
});

commands.forEach(function (cmd) {

    Client.prototype[cmd] = function (args, callback) {
        
        var c = this._client, log;

        if (typeof args === 'string') {
            args = [args];
        }

        if (!args) args = [];

        log = this._adapter.logger(cmd.toUpperCase() + ' ' + args.map(function (a) {
            if (typeof a === 'object') return JSON.stringify(a);
            return a;
        }).join(' '));
        args.push(function (err, res) {
            if (err) console.log(err);
            log();
            if (callback) {
                callback(err, res);
            }
        });

        c[cmd].apply(c, args);
    };
});

Client.prototype.multi = function (commands, callback) {
    if (commands.length === 0) return callback && callback();
    if (commands.length === 1) {
        return this[commands[0].shift().toLowerCase()].call(
            this,
            commands[0],
            callback && function (e, r) { callback(e, [r]) });
    }
    var log = this._adapter.logger('MULTI\n  ' + commands.map(function (x) {
        return x.join(' ');
    }).join('\n  ') + '\nEXEC');
    this._client.multi(commands).exec(function (err, replies) {
        if (err) console.log(err);
        log();
        callback && callback(err, replies);
    });
};

Client.prototype.transaction = function () {
    return new Transaction(this);
};

function Transaction(client) {
    this._client = client;
    this._handlers = [];
    this._schedule = [];
}

Transaction.prototype.run = function (cb) {
    var t = this;
    var atLeastOneHandler = false;
    switch (this._schedule.length) {
        case 0: return cb();
        case 1: return this._client[this._schedule[0].shift()].call(
        this._client,
        this._schedule[0],
        this._handlers[0] || cb);
        default:
        this._client.multi(this._schedule, function (err, replies) {
            if (err) return cb(err);
            replies.forEach(function (r, i) {
                if (t._handlers[i]) {
                    atLeastOneHandler = true;
                    t._handlers[i](err, r);
                }
            });
            if (!atLeastOneHandler) cb(err);
        });
    }

};

commands.forEach(function (k) {

    Transaction.prototype[k] = function (args, cb) {
        if (typeof args === 'string') {
            args = [args];
        }
        args.unshift(k);
        this._schedule.push(args);
        this._handlers.push(cb || false);
    };

});

function BridgeToRedis(client) {
    this._models = {};
    this.client = client;
    this.indexes = {};
}

BridgeToRedis.prototype.define = function (descr) {
    var m = descr.model.modelName;
    this._models[m] = descr;
    this.indexes[m] = {};
    Object.keys(descr.properties).forEach(function (prop) {
        if (descr.properties[prop].index) {
            this.indexes[m][prop] = descr.properties[prop].type;
        }
    }.bind(this));
};

BridgeToRedis.prototype.defineForeignKey = function (model, key, cb) {
    this.indexes[model][key] = Number;
    cb(null, Number);
};

BridgeToRedis.prototype.forDb = function (model, data) {
    var p = this._models[model].properties;
    for (var i in data) {
        if (p[i] && p[i].type.name === 'Date') {
            data[i] = data[i] && data[i].getTime ? data[i].getTime() : 0;
        } else if (p[i] && [
            'String', 'Text', 'Number', 'Boolean', 'Date'
        ].indexOf(p[i].type.name) === -1) {
            data[i] = JSON.stringify(data[i]);
        }
    }
    return data;
};

BridgeToRedis.prototype.fromDb = function (model, data) {
    var p = this._models[model].properties;
    for (var i in data) {
        if (p[i] && p[i].type.name === 'Date') {
            if (isNaN(parseInt(data[i]))) {
                data[i] = new Date(data[i]);
            } else {
                var ms = data[i];
                data[i] = new Date();
                data[i].setTime(ms);
            }
        } else if (p[i] && [
            'String', 'Text', 'Number', 'Boolean', 'Date'
        ].indexOf(p[i].type.name) === -1) {
            try {
                data[i] = JSON.parse(data[i]);
            } catch (e) {}
        }
    }
    return data;
};

BridgeToRedis.prototype.save = function (model, data, callback) {
    data = this.forDb(model, data);
    deleteNulls(data);
    this.client.hgetall(model + ':' + data.id, function (err, prevData) {
        if (err) return callback(err);
        this.client.hmset([model + ':' + data.id, data], function (err) {
            if (err) return callback(err);
            this.updateIndexes(model, data.id, data, callback, this.forDb(model, prevData));
        }.bind(this));
    }.bind(this));
};

BridgeToRedis.prototype.updateIndexes = function (model, id, data, callback, prevData) {
    var p = this._models[model].properties;
    var i = this.indexes[model];
    var schedule = [];
    if (!callback.removed) {
        schedule.push(['SADD', 's:' + model, id]);
    }
    Object.keys(i).forEach(function (key) {
        if (data.hasOwnProperty(key)) {
            var val = data[key];
            schedule.push([
                'SADD',
                'i:' + model + ':' + key + ':' + val,
                id
            ]);
        }
        if (prevData && prevData[key] !== data[key]) {
            schedule.push([
                'SREM',
                'i:' + model + ':' + key + ':' + prevData[key],
                id
            ]);
        }
    });

    if (schedule.length) {
        this.client.multi(schedule, function (err) {
            callback(err, data);
        });
    } else {
        callback(null);
    }
};

BridgeToRedis.prototype.create = function (model, data, callback) {
    if (data.id) return create.call(this, data.id, true);

    this.client.incr('id:' + model, function (err, id) {
        create.call(this, id);
    }.bind(this));

    function create(id, upsert) {
        data.id = id;
        this.save(model, data, function (err) {
            if (callback) {
                callback(err, id);
            }
        });

        // push the id to the list of user ids for sorting
        this.client.sadd(['s:' + model, data.id]);
    }
};

BridgeToRedis.prototype.updateOrCreate = function (model, data, callback) {
    if (!data.id) {
        return this.create(model, data, callback);
    }
    var client = this.client;
    this.save(model, data, function (error, obj) {
        var key = 'id:' + model;
        client.get(key, function (err, id) {
            if (!id || data.id > parseInt(id, 10)) {
                client.set([key, data.id], ok);
            } else {
                ok();
            }
        });
        function ok() {
            callback(error, obj);
        }
    });
};

BridgeToRedis.prototype.exists = function (model, id, callback) {
    this.client.exists(model + ':' + id, function (err, exists) {
        if (callback) {
            callback(err, exists);
        }
    });
};

BridgeToRedis.prototype.find = function find(model, id, callback) {
    this.client.hgetall(model + ':' + id, function (err, data) {
        if (data && Object.keys(data).length > 0) {
            data.id = id;
        } else {
            data = null;
        }
        callback(err, this.fromDb(model, data));
    }.bind(this));
};

BridgeToRedis.prototype.destroy = function destroy(model, id, callback) {
    var br = this;
    var tr = br.client.transaction();

    br.client.hgetall(model + ':' + id, function (err, data) {
        if (err) return callback(err);

        tr.srem(['s:' + model, id]);
        tr.del(model + ':' + id);
        tr.run(function (err) {
            if (err) return callback(err);
            callback.removed = true;

            br.updateIndexes(model, id, {}, callback, data);
        });
    });
};

BridgeToRedis.prototype.possibleIndexes = function (model, filter) {
    if (!filter || Object.keys(filter.where || {}).length === 0) return false;

    var foundIndex = [];
    var noIndex = [];
    Object.keys(filter.where).forEach(function (key) {
        var i = this.indexes[model][key];
        if (i) {
            var val = filter.where[key];
            if (i.name === 'Date') {
                val = val && val.getTime ? val.getTime() : 0;
            }
            foundIndex.push('i:' + model + ':' + key + ':' + val);
        } else {
            noIndex.push(key);
        }
    }.bind(this));

    return [foundIndex, noIndex];
};

BridgeToRedis.prototype.all = function all(model, filter, callback) {
    var ts = Date.now();
    var client = this.client;
    var cmd;
    var redis = this;
    var sortCmd = [];
    var props = this._models[model].properties;
    var allNumeric = true;
    var dest = 'temp' + (Date.now() * Math.random());
    var innerSetUsed = false;
    var trans = this.client.transaction();

    if (!filter) {
        filter = {order: 'id'};
    }

    // WHERE
    if (filter.where) {
        var pi = this.possibleIndexes(model, filter);
        var indexes = pi[0];
        var noIndexes = pi[1];

        if (noIndexes.length) {
            throw new Error(model + ': no indexes found for ' +
            noIndexes.join(', ') +
            ' impossible to sort and filter using redis adapter');
        }

        if (indexes && indexes.length) {
            innerSetUsed = true;
            if (indexes.length > 1) {
                trans.sinterstore(indexes);
            } else {
                dest = indexes[0];
            }
        } else {
            throw new Error('No indexes for ' + filter.where);
        }
    } else {
        dest = 's:' + model;
        // no filtering, just sort/limit (if any)
    }

    // only counting?
    if (filter.getCount) {
        trans.scard(dest, callback);
        return trans.run();
    }

    // ORDER
    var reverse = false;
    if (!filter.order) {
        filter.order = 'id';
    }
    var orders = filter.order;
    if (typeof filter.order === "string"){
        orders = [filter.order];
    }

    orders.forEach(function (key) {
        var m = key.match(/\s+(A|DE)SC$/i);
        if (m) {
            key = key.replace(/\s+(A|DE)SC/i, '');
            if (m[1] === 'DE') reverse = true;
        }
        if (key !== 'id') {
            if (props[key].type.name !== 'Number' && props[key].type.name !== 'Date') {
                allNumeric = false;
            }
        }
        sortCmd.push("BY", model + ":*->" + key);
    });

    // LIMIT
    if (filter.limit){
        var from = (filter.offset || 0), to = from + filter.limit;
        sortCmd.push("LIMIT", from, to);
    }

    // we need ALPHA modifier when sorting string values
    // the only case it's not required - we sort numbers
    if (!allNumeric) {
        sortCmd.push('ALPHA');
    }

    if (reverse) {
        sortCmd.push('DESC');
    }

    sortCmd.unshift(dest);
    sortCmd.push("GET", "#");
    cmd = "SORT " + sortCmd.join(" ");
    var ttt = Date.now();
    trans.sort(sortCmd, function (err, ids){
        if (err) {
            return callback(err, []);
        }
        var sortedKeys = ids.map(function (i) {
            return model + ":" + i;
        });
        handleKeys(err, sortedKeys);
    });

    if (dest.match(/^temp/)) {
        trans.del(dest);
    }

    trans.run(callback);

    function handleKeys(err, keys) {
        var t2 = Date.now();
        var query = keys.map(function (key) {
            return ['hgetall', key];
        });
        client.multi(query, function (err, replies) {
            callback(err, (replies || []).map(function (r) {
                return redis.fromDb(model, r);
            }));
        });
    }

    return;

    function numerically(a, b) {
        return a[this[0]] - b[this[0]];
    }

    function literally(a, b) {
        return a[this[0]] > b[this[0]];
    }

};

BridgeToRedis.prototype.destroyAll = function destroyAll(model, callback) {
    var br = this;
    this.client.multi([
        ['KEYS', model + ':*'],
        ['KEYS', '*:' + model + ':*']
    ], function (err, k) {
        br.client.del(k[0].concat(k[1]).concat('s:' + model), callback);
    });

};

BridgeToRedis.prototype.count = function count(model, callback, where) {
    if (where && Object.keys(where).length) {
        this.all(model, {where: where, getCount: true}, callback);
    } else {
        this.client.scard('s:' + model, callback);
    }
};

BridgeToRedis.prototype.updateAttributes = function updateAttrs(model, id, data, cb) {
    data.id = id;
    this.save(model, data, cb);
};

function deleteNulls(data) {
    Object.keys(data).forEach(function (key) {
        if (data[key] === null) delete data[key];
    });
}

BridgeToRedis.prototype.disconnect = function disconnect() {
    this.client.quit();
};