var db = require("../database");
var Logger = require("../logger");
var Q = require("q");

const DB_VERSION = 4;
var hasUpdates = [];

module.exports.checkVersion = function () {
    db.query("SELECT `key`,`value` FROM `meta` WHERE `key`=?", ["db_version"], function (err, rows) {
        if (err) {
            return;
        }

        if (rows.length === 0) {
            Logger.errlog.log("[Warning] db_version key missing from database.  Setting " +
                              "db_version=" + DB_VERSION);
            db.query("INSERT INTO `meta` (`key`, `value`) VALUES ('db_version', ?)",
                     [DB_VERSION],
                     function (err) {
            });
        } else {
            var v = parseInt(rows[0].value);
            if (v >= DB_VERSION) {
                return;
            }
            var next = function () {
                hasUpdates.push(v);
                Logger.syslog.log("Updated database to version " + v);
                if (v < DB_VERSION) {
                    update(v++, next);
                } else {
                    db.query("UPDATE `meta` SET `value`=? WHERE `key`='db_version'",
                             [DB_VERSION]);
                }
            };
            update(v++, next);
        }
    });
};

function update(version, cb) {
    if (version < 3 && hasUpdates.indexOf(2) < 0) {
        addMetaColumnToLibraries(cb);
    } else if (version < 4) {
        Q.allSettled([
            Q.nfcall(mergeChannelLibraries),
            Q.nfcall(mergeChannelRanks),
            Q.nfcall(mergeChannelBans)
        ]).done(function () {
            Logger.syslog.log("Merged channel tables.  Please verify that everything " +
                              "is working correctly, and then type '/delete_old_tables'" +
                              " into the CyTube process to remove the unused tables.");
            cb();
        })
    }
}

function addMetaColumnToLibraries(cb) {
    Logger.syslog.log("[database] db version indicates channel libraries don't have " +
                      "meta column.  Updating...");
    Q.nfcall(db.query, "SHOW TABLES")
    .then(function (rows) {
        rows = rows.map(function (r) {
            return r[Object.keys(r)[0]];
        }).filter(function (r) {
            return r.match(/_library$/);
        });

        var queue = [];
        rows.forEach(function (table) {
            queue.push(Q.nfcall(db.query, "ALTER TABLE `" + table + "` ADD meta TEXT")
                .then(function () {
                    Logger.syslog.log("Added meta column to " + table);
                })
            );
        });

        return Q.all(queue);
    }).catch(function (err) {
        Logger.errlog.log("Adding meta column to library tables failed: " + err);
    }).done(cb);
}

function mergeChannelLibraries(cb) {
    Q.nfcall(db.query, "SHOW TABLES")
    .then(function (rows) {
        rows = rows.map(function (r) {
            return r[Object.keys(r)[0]];
        }).filter(function (r) {
            return r.match(/chan_(.*)?_library$/);
        });

        var queue = [];
        rows.forEach(function (table) {
            var name = table.match(/chan_(.*?)_library$/)[1];
            queue.push(Q.nfcall(db.query,
                "INSERT INTO `channel_libraries` SELECT id, title, seconds, type, meta, ?" +
                " AS channel FROM `" + table + "`", [name])
                .then(function () {
                    Logger.syslog.log("Copied " + table + " to channel_libraries");
                }).catch(function (err) {
                    Logger.errlog.log("Copying " + table + " to channel_libraries failed: " +
                        err);
                    if (err.stack) {
                        Logger.errlog.log(err.stack);
                    }
                })
            );
        });

        return Q.all(queue);
    }).catch(function (err) {
        Logger.errlog.log("Copying libraries to channel_libraries failed: " + err);
        if (err.stack) {
            Logger.errlog.log(err.stack);
        }
    }).done(function () { cb(null); });
}

function mergeChannelRanks(cb) {
    Q.nfcall(db.query, "SHOW TABLES")
    .then(function (rows) {
        rows = rows.map(function (r) {
            return r[Object.keys(r)[0]];
        }).filter(function (r) {
            return r.match(/chan_(.*?)_ranks$/);
        });

        var queue = [];
        rows.forEach(function (table) {
            var name = table.match(/chan_(.*?)_ranks$/)[1];
            queue.push(Q.nfcall(db.query,
                "INSERT INTO `channel_ranks` SELECT name, rank, ?" +
                " AS channel FROM `" + table + "`", [name])
                .then(function () {
                    Logger.syslog.log("Copied " + table + " to channel_ranks");
                }).catch(function (err) {
                    Logger.errlog.log("Copying " + table + " to channel_ranks failed: " +
                        err);
                    if (err.stack) {
                        Logger.errlog.log(err.stack);
                    }
                })
            );
        });

        return Q.all(queue);
    }).catch(function (err) {
        Logger.errlog.log("Copying ranks to channel_ranks failed: " + err);
        if (err.stack) {
            Logger.errlog.log(err.stack);
        }
    }).done(function () { cb(null); });
}

function mergeChannelBans(cb) {
    Q.nfcall(db.query, "SHOW TABLES")
    .then(function (rows) {
        rows = rows.map(function (r) {
            return r[Object.keys(r)[0]];
        }).filter(function (r) {
            return r.match(/chan_(.*?)_bans$/);
        });

        var queue = [];
        rows.forEach(function (table) {
            var name = table.match(/chan_(.*?)_bans$/)[1];
            queue.push(Q.nfcall(db.query,
                "INSERT INTO `channel_bans` SELECT id, ip, name, bannedby, reason, ?" +
                " AS channel FROM `" + table + "`", [name])
                .then(function () {
                    Logger.syslog.log("Copied " + table + " to channel_bans");
                }).catch(function (err) {
                    Logger.errlog.log("Copying " + table + " to channel_bans failed: " +
                        err);
                    if (err.stack) {
                        Logger.errlog.log(err.stack);
                    }
                })
            );
        });

        return Q.all(queue);
    }).catch(function (err) {
        Logger.errlog.log("Copying ranks to channel_bans failed: " + err);
        if (err.stack) {
            Logger.errlog.log(err.stack);
        }
    }).done(function () { cb(null); });
}

module.exports.deleteOldChannelTables = function (cb) {
    Q.nfcall(db.query, "SHOW TABLES")
    .then(function (rows) {
        rows = rows.map(function (r) {
            return r[Object.keys(r)[0]];
        }).filter(function (r) {
            return r.match(/chan_(.*?)_(library|ranks|bans)$/);
        });

        var queue = [];
        rows.forEach(function (table) {
            queue.push(Q.nfcall(db.query, "DROP TABLE `" + table + "`")
                .then(function () {
                    Logger.syslog.log("Deleted " + table);
                }).catch(function (err) {
                    Logger.errlog.log("Deleting " + table + " failed: " + err);
                    if (err.stack) {
                        Logger.errlog.log(err.stack);
                    }
                })
            );
        });

        return Q.all(queue);
    }).catch(function (err) {
        Logger.errlog.log("Deleting old tables failed: " + err);
        if (err.stack) {
            Logger.errlog.log(err.stack);
        }
    }).done(cb);
};