"use strict";

var db = require('./database'),
	async = require('async'),
	winston = require('winston'),

	Upgrade = {},

	minSchemaDate = Date.UTC(2015, 7, 18),		// This value gets updated every new MINOR version
	schemaDate, thisSchemaDate,

	// IMPORTANT: REMEMBER TO UPDATE VALUE OF latestSchema
	latestSchema = Date.UTC(2015, 10, 6);

Upgrade.check = function(callback) {
	db.get('schemaDate', function(err, value) {
		if (err) {
			return callback(err);
		}

		if (!value) {
			db.set('schemaDate', latestSchema, function(err) {
				if (err) {
					return callback(err);
				}
				callback(null);
			});
			return;
		}

		var schema_ok = parseInt(value, 10) >= latestSchema;
		callback(!schema_ok ? new Error('schema-out-of-date') : null);
	});
};

Upgrade.update = function(schemaDate, callback) {
	db.set('schemaDate', schemaDate, callback);
};

Upgrade.upgrade = function(callback) {
	var updatesMade = false;

	winston.info('Beginning database schema update');

	async.series([
		function(next) {
			// Prepare for upgrade & check to make sure the upgrade is possible
			db.get('schemaDate', function(err, value) {
				if(!value) {
					db.set('schemaDate', latestSchema, function() {
						next();
					});
					schemaDate = latestSchema;
				} else {
					schemaDate = parseInt(value, 10);
				}

				if (schemaDate >= minSchemaDate) {
					next();
				} else {
					next(new Error('upgrade-not-possible'));
				}
			});
		},
		function(next) {
			thisSchemaDate = Date.UTC(2015, 8, 30);
			if (schemaDate < thisSchemaDate) {
				updatesMade = true;
				winston.info('[2015/09/30] Converting default Gravatar image to default User Avatar');

				async.waterfall([
					async.apply(db.isObjectField, 'config', 'customGravatarDefaultImage'),
					function(keyExists, _next) {
						if (keyExists) {
							_next();
						} else {
							winston.info('[2015/09/30] Converting default Gravatar image to default User Avatar skipped');
							Upgrade.update(thisSchemaDate, next);
							next();
						}
					},
					async.apply(db.getObjectField, 'config', 'customGravatarDefaultImage'),
					async.apply(db.setObjectField, 'config', 'defaultAvatar'),
					async.apply(db.deleteObjectField, 'config', 'customGravatarDefaultImage')
				], function(err) {
					if (err) {
						return next(err);
					}

					winston.info('[2015/09/30] Converting default Gravatar image to default User Avatar done');
					Upgrade.update(thisSchemaDate, next);
				});
			} else {
				winston.info('[2015/09/30] Converting default Gravatar image to default User Avatar skipped');
				next();
			}
		},
		function(next) {
			thisSchemaDate = Date.UTC(2015, 10, 6);
			if (schemaDate < thisSchemaDate) {
				updatesMade = true;
				winston.info('[2015/11/06] Removing gravatar');

				db.getSortedSetRange('users:joindate', 0, -1, function(err, uids) {
					if (err) {
						return next(err);
					}

					async.eachLimit(uids, 500, function(uid, next) {
						db.getObjectFields('user:' + uid, ['picture', 'gravatarpicture'], function(err, userData) {
							if (err) {
								return next(err);
							}

							if (!userData.picture || !userData.gravatarpicture) {
								return next();
							}

							if (userData.gravatarpicture === userData.picture) {
								async.series([
									function (next) {
										db.setObjectField('user:' + uid, 'picture', '', next);
									},
									function (next) {
										db.deleteObjectField('user:' + uid, 'gravatarpicture', next);	
									}
								], next);
							} else {
								db.deleteObjectField('user:' + uid, 'gravatarpicture', next);
							}
						});
					}, function(err) {
						if (err) {
							return next(err);
						}

						winston.info('[2015/11/06] Gravatar pictures removed!');
						Upgrade.update(thisSchemaDate, next);
					});
				});

			} else {
				winston.info('[2015/11/06] Gravatar removal skipped');
				next();
			}
		}

		// Add new schema updates here
		// IMPORTANT: REMEMBER TO UPDATE VALUE OF latestSchema IN LINE 24!!!
	], function(err) {
		if (!err) {
			if(updatesMade) {
				winston.info('[upgrade] Schema update complete!');
			} else {
				winston.info('[upgrade] Schema already up to date!');
			}
		} else {
			switch(err.message) {
			case 'upgrade-not-possible':
				winston.error('[upgrade] NodeBB upgrade could not complete, as your database schema is too far out of date.');
				winston.error('[upgrade]   Please ensure that you did not skip any minor version upgrades.');
				winston.error('[upgrade]   (e.g. v0.1.x directly to v0.3.x)');
				break;

			default:
				winston.error('[upgrade] Errors were encountered while updating the NodeBB schema: ' + err.message);
				break;
			}
		}

		if (typeof callback === 'function') {
			callback(err);
		} else {
			process.exit();
		}
	});
};

module.exports = Upgrade;