/**
 * Author: Toan Nguyen Dinh
 * Email: Toan@tabvn.com
 * Created: Sep 02, 2017
 */


/**
 * Requires of modules
 */
const fs = require('fs');
const path = require('path');
const spawn = require('child_process').spawn;
const _ = require('lodash');
const moment = require('moment');
const tmp = require('tmp');
tmp.setGracefulCleanup();

/**
 * Amazone S3
 *
 */
const AWS = require('aws-sdk');
AWS.config.loadFromPath('aws.json');
const s3 = new AWS.S3();


/**
 * End Amazon S3
 */

/**
 * End requires modules
 *
 */

/**
 * Begin Express 4
 */
const PORT = 3003;
const express = require('express');
const bodyParser = require('body-parser');
const app = express();
app.use(bodyParser.json()); // for parsing application/json
app.use(bodyParser.urlencoded({extended: true})); // for parsing application/x-www-form-urlencoded

/**
 * End of Express
 */

/**
 *Begin Variables
 */
const DATABASE_BACKUP = 'database';
const CODE_BACKUP = 'code';
const FULL = 'full';


let production = false;

let devConfig = {
    mongodb: 'dashboard',
    bucket: 'tom.tabvn.com'
};

let productionConfig = {
    mongodb: 'dashboard',
    bucket: 'producer.livex.tv'
};

let config = production ? productionConfig : devConfig;

let backups = []; // array of processing backup
let backupErrors = []; // Array items of backup error
let restore = null;

/**
 * End variables
 */

let upload = (fileName, filePath, callback) => {

    let file = fs.createReadStream(filePath);
    let params = {Bucket: config.bucket, Key: fileName, Body: file};

    s3.putObject(params, function (err, data) {
        if (err) {
            console.log(err);
            if (callback) {
                return callback(err);
            }

        } else {
            if (callback) {
                return callback(null, data);
            }

        }

    });
};

let getBackupFiles = (callback) => {

    s3.listObjects({
        Bucket: config.bucket,
        MaxKeys: 100
    }, function (err, data) {
        if (callback) {
            return callback(err, data);
        }
    });

};


let deleteBackupFile = (key, callback) => {

    let params = {
        Bucket: config.bucket,
        Key: key
    };
    s3.deleteObject(params, function (err, data) {
        if (callback) {
            return callback(err, data);
        }
    });
}

let getDownloadUrl = (key = "", callback) => {

    let ONE_DAY = 60 * 60 * 24;
    let params = {
        Bucket: config.bucket,
        Key: key,
        Expires: ONE_DAY
    };


    s3.getSignedUrl('getObject', params, (err, data) => {

        if (err) {
            if (callback) {
                return callback(err);
            }
        }
        else {
            return callback(null, data);

        }


    });

};


let getBackupFileObject = (key = "", callback) => {

    let params = {
        Bucket: config.bucket,
        Key: key
    };

    s3.getObject(params, (err, data) => {

        if (callback) {
            return callback(err, data);
        }
    })


};


let compress = (pathToArchive, directoryPath, callback) => {
    let compressProcess = spawn('tar', ['zcvf', pathToArchive, '-C', directoryPath, '.']);

    compressProcess.on('exit', (code) => {
        if (code === 0) {
            if (callback) {
                return callback(null, true);
            }
        } else {
            let error = new Error("Error", code);
            if (callback) {
                return callback(error);
            }
        }
    })
};

let extract = (pathToArchive, directoryPath, callback) => {

    let extractProcess = spawn('tar', ['xvzf', pathToArchive, '-C', directoryPath]);
    extractProcess.on('exit', (code) => {

        if (code === 0) {
            if (callback) {
                return callback(null, true);
            }

        } else {
            let error = new Error("Error", code);
            if (callback) {
                return callback(error);
            }
        }
    });

};


let createFileName = (backup, ext = 'tar.gz') => {

    let names = [];
    let space = "---";
    let underSpace = '___';

    let snapshot = backup.snapshot ? backup.snapshot : "null";
    snapshot = _.replace(snapshot, /---/g, " ");
    snapshot = _.replace(snapshot, /___/g, " ");
    snapshot = _.replace(snapshot, /\//g, " ");
    snapshot = _.trim(snapshot);

    names.push('snapshot' + space + (snapshot));
    names.push('backupType' + space + backup.backupType);
    names.push('manually' + space + (backup.manually ? "true" : "false"));
    names.push('createdAt' + space + moment(backup.createdAt).unix());
    names.push('ext' + space + ext + underSpace);
    return _.join(names, underSpace) + '.' + ext;
};

let getObjectStructFromFileName = (filename) => {

    let space = "---";
    let underSpace = '___';

    let splitUnderScore = _.split(filename, underSpace);
    let snapshot = splitUnderScore && splitUnderScore[0] ? _.split(splitUnderScore[0], space) : null;
    let backupType = splitUnderScore && splitUnderScore[1] ? _.split(splitUnderScore[1], space) : null;
    let manually = splitUnderScore && splitUnderScore[2] ? _.split(splitUnderScore[2], space) : null;
    let createdAt = splitUnderScore && splitUnderScore[3] ? _.split(splitUnderScore[3], space) : null;
    let obj = {
        key: filename,
        snapshot: snapshot && snapshot[1] && snapshot[1] && snapshot[1] !== 'null' ? snapshot[1] : "",
        backupType: backupType && backupType[1] ? backupType[1] : null,
        manually: manually && manually[1] === 'true' ? true : false,
        createdAt: createdAt && createdAt[1] ? moment.unix(createdAt[1]).toDate() : null,
        size: 0,
        tag: null,
    };
    return obj;

};

let backupDatabase = (backup, callback) => {


    let tmpDirGenerate = tmp.dirSync({prefix: "livex-", unsafeCleanup: true});
    let tmpDir = tmpDirGenerate.name;
    let fileName = createFileName(backup, 'tar.gz');
    let dir = path.join(tmpDir, Date.now().toString());

    let arg = ['--db', config.mongodb, '--out', dir];
    let exportDatabaseProcess = spawn('mongodump', arg);
    let filePath = path.join(tmpDir, fileName);

    exportDatabaseProcess.on('exit', (code) => {

        if (code === 0) {
            compress(filePath, dir, (err, success) => {

                if (err) {
                    if (callback) {
                        return callback(err);
                    }

                } else {
                    upload(fileName, filePath, (err, data) => {
                        // delete the file
                        tmpDirGenerate.removeCallback();

                        if (err) {
                            if (callback) {
                                return callback(err);
                            }

                        } else {
                            if (callback) {
                                return callback(null, data);
                            }
                        }

                    });
                }
            });

        } else {
            console.log("Backup database error with code: ", code);
            if (callback) {
                return callback(new Error("An error backup with code:", code));
            }
        }
    })

};

let backupSourceCode = (backup) => {


};

let fullBackup = (backup) => {

    backupDatabase(backup, (err, success) => {
        console.log(err, success);
    });

    backupSourceCode(backup);

};

let doBackup = (backup) => {

    if (backup.backupType === DATABASE_BACKUP) {
        backupDatabase(backup, (err, success) => {
            console.log("backup database process:", err, success);
            // so let remove pending backup item.
            backups = _.filter(backups, (b) => b.id !== backup.id);
            if (err === null && success) {
                backups = _.filter(backups, (b) => b.id !== backup.id);
            } else {
                // if error so we do need add this backup item as error item. log it.
                backupErrors.push(backup);
            }
        });
    } else if (backup.backupType === CODE_BACKUP) {
        backupSourceCode(backup);
    } else {
        fullBackup(backup);
    }

};


let restoreDatabase = (backup, callback) => {


    let params = {
        Bucket: config.bucket,
        Key: backup.key
    };

    let tmpDirGenerate = tmp.dirSync({prefix: "livex-restore", unsafeCleanup: true});
    let tmpDownloadDir = tmpDirGenerate.name;
    let filePath = path.join(tmpDownloadDir, backup.key);
    let file = fs.createWriteStream(filePath);

    file.on('close', function () {
        // now need extract the database file
        extract(filePath, tmpDownloadDir, (err, success) => {
            if (err) {
                return callback(err);
            } else {
                // remove the file
                fs.unlinkSync(filePath);
                console.log("Begin restore the database");
                let arg = ['--db', config.mongodb, path.join(tmpDownloadDir, config.mongodb)];
                let restoreMongoProcess = spawn('mongorestore', arg);

                restoreMongoProcess.stderr.on('data', (data) => {

                });

                restoreMongoProcess.on('exit', (code) => {
                    console.log("exit with code", code);
                    if (code === 0) {
                        tmpDirGenerate.removeCallback();
                        return callback(null, true);
                    } else {
                        return callback(new Error("An error restore the database with code: ", code));
                    }
                });

            }
        });
    });
    s3.getObject(params).createReadStream().on('error', function (err) {
        return callback(err);
    }).pipe(file);


};

let restoreSourceCode = (backup) => {

};

let fullRestore = (backup) => {


};

let doRestore = (key) => {
    let backupObject = getObjectStructFromFileName(key);

    restore = backupObject;

    if (backupObject.backupType === DATABASE_BACKUP) {
        restoreDatabase(backupObject, (err, success) => {
            console.log("The restore status: ", err, success);
            if (err === null && success) {
                // success
                restore = null;
            }
        });
    } else if (backupObject.backupType === CODE_BACKUP) {
        restoreSourceCode(backupObject);
    } else {
        fullRestore(backupObject);
    }
};

let handleError = (res, error = null, code = 503) => {
    return res.status(code).send(error);
};

/**
 * GET homepage.
 */

app.get('/', function (req, res) {
    res.send('Livex Service Application.')
});


/**
 * GET router for /backups list all backups files from s3
 */
app.get('/backups', (req, res, next) => {


    let backupItems = [];


    getBackupFiles((err, data) => {

        if (err) {
            return next(err);
        } else {
            if (typeof data !== 'undefined' && data !== null && typeof data.Contents !== 'undefined' && data.Contents !== null) {
                _.each(data.Contents, (item) => {
                    // let destruct from item file name.
                    let obj = getObjectStructFromFileName(item.Key);
                    // we also need file size to display.
                    obj.size = item.Size;
                    // add ETag to object in case use later to request to s3
                    obj.tag = _.replace(item.ETag, /"/g, "");
                    backupItems.push(obj);
                });
            }
            // let sort the array, latest backups items will show first.
            backupItems.sort((a, b) => {
                let dateA = new Date(moment(a.createdAt));
                let dateB = new Date(moment(b.createdAt));
                return dateB - dateA;
            });

            return res.json(backupItems);
        }
    });


});


/**
 *
 * DELETE Router for /backups/:key
 */

app.delete('/backups/:key', (req, res, next) => {


    if (typeof req.params.key !== "undefined" && req.params.key !== null) {
        let key = req.params.key;
        deleteBackupFile(key, (err, data) => {
            if (err) {
                return handleError(res, err, 404);
            } else {
                return res.json({success: true});
            }
        })
    } else {
        return handleError(res, 'Backup does not exist', 404);

    }


});

/**
 * GET download backup
 */

app.get('/backups/:key/download', (req, res, next) => {
    if (typeof req.params.key !== "undefined" && req.params.key !== null) {
        let key = req.params.key;
        getDownloadUrl(key, (err, data) => {
            if (err) {
                return handleError(res, err);
            } else {
                return res.json({url: data});
            }

        });


    } else {
        return handleError(res, 'Backup does not exist', 404);

    }
});


/**
 * POST router for restore a backup
 */

app.post('/backups/restore', (req, res) => {

    let data = req.body;
    let force = data.force ? data.force : false;
    if (restore !== null && !force) {
        // we dont allow restore white having restore processs.
        return handleError(res, 'Another restore process is running.', 503);
    }
    if (typeof data !== "undefined" && data !== null && data.key !== null) {
        let key = data.key;
        getBackupFileObject(key, (err, data) => {
            if (err) {
                return handleError(res, err, 404);
            } else {
                doRestore(key);
                return res.json({message: "Starting restore process."});
            }
        });
    } else {
        return handleError(res, 'Backup Does not exist', 404);
    }


});

/**
 * GET Router for /backups/pending
 * List all processing backups
 */

app.get('/backups/pending', (req, res) => {
    return res.json(backups);
});


/**
 * GET router for /backups/errors
 * Log all backups as errors
 */
app.get('/backups/errors', (req, res) => {
    return res.json(backupErrors);
});

/**
 * GET router /backups/errors/clear
 * Clear all errors logs
 */

app.get('/backups/errors/clear', (req, res) => {

    backupErrors = [];
    return res.json(backupErrors);

});

/**
 * POST /backups/create
 * create new backup
 */
app.post('/backups/create', function (req, res) {

    let data = req.body;

    if (typeof data === "undefined" || typeof data.id === "undefined" || data.id === null || typeof data.backupType === "undefined" || data.backupType === null || typeof data.manually === "undefined" || data.manually === null) {
        return handleError(res, "An error", 503);
    }
    let backup = {
        id: data.id ? data.id : null,
        snapshot: data.snapshot ? data.snapshot : "",
        manually: data.manually ? data.manually : false,
        backupType: data.backupType ? data.backupType : DATABASE_BACKUP,
        createdAt: data.createdAt ? data.createdAt : Date.now(),
        updatedAt: data.updatedAt ? data.updatedAt : Date.now(),
        status: "pending"
    };

    backups.push(backup);
    doBackup(backup);
    return res.send(req.body);
});


/**
 * Start app service
 */
app.listen(PORT, function () {
    console.log('Service is running on port:', PORT)
});