'use strict';

const log = require('npmlog');
const config = require('wild-config');
const IMAPServerModule = require('./imap-core');
const IMAPServer = IMAPServerModule.IMAPServer;
const ImapNotifier = require('./lib/imap-notifier');
const Indexer = require('./imap-core/lib/indexer/indexer');
const MessageHandler = require('./lib/message-handler');
const UserHandler = require('./lib/user-handler');
const MailboxHandler = require('./lib/mailbox-handler');
const db = require('./lib/db');
const consts = require('./lib/consts');
const RedFour = require('ioredfour');
const packageData = require('./package.json');
const yaml = require('js-yaml');
const fs = require('fs');
const certs = require('./lib/certs');
const setupIndexes = yaml.safeLoad(fs.readFileSync(__dirname + '/indexes.yaml', 'utf8'));

const onFetch = require('./lib/handlers/on-fetch');
const onAuth = require('./lib/handlers/on-auth');
const onList = require('./lib/handlers/on-list');
const onLsub = require('./lib/handlers/on-lsub');
const onSubscribe = require('./lib/handlers/on-subscribe');
const onUnsubscribe = require('./lib/handlers/on-unsubscribe');
const onCreate = require('./lib/handlers/on-create');
const onRename = require('./lib/handlers/on-rename');
const onDelete = require('./lib/handlers/on-delete');
const onOpen = require('./lib/handlers/on-open');
const onStatus = require('./lib/handlers/on-status');
const onAppend = require('./lib/handlers/on-append');
const onStore = require('./lib/handlers/on-store');
const onExpunge = require('./lib/handlers/on-expunge');
const onCopy = require('./lib/handlers/on-copy');
const onMove = require('./lib/handlers/on-move');
const onSearch = require('./lib/handlers/on-search');
const onGetQuotaRoot = require('./lib/handlers/on-get-quota-root');
const onGetQuota = require('./lib/handlers/on-get-quota');

let logger = {
    info(...args) {
        args.shift();
        log.info('IMAP', ...args);
    },
    debug(...args) {
        args.shift();
        log.silly('IMAP', ...args);
    },
    error(...args) {
        args.shift();
        log.error('IMAP', ...args);
    }
};

let indexer;
let notifier;
let messageHandler;
let userHandler;
let mailboxHandler;
let gcTimeout;
let gcLock;

function clearExpiredMessages() {
    clearTimeout(gcTimeout);
    let startTime = Date.now();

    // First, acquire the lock. This prevents multiple connected clients for deleting the same messages
    gcLock.acquireLock('gc_expired', Math.round(consts.GC_INTERVAL * 1.2) /* Lock expires if not released */, (err, lock) => {
        if (err) {
            logger.error(
                {
                    tnx: 'gc',
                    err
                },
                'Failed to acquire lock error=%s',
                err.message
            );
            gcTimeout = setTimeout(clearExpiredMessages, consts.GC_INTERVAL);
            gcTimeout.unref();
            return;
        } else if (!lock.success) {
            logger.debug(
                {
                    tnx: 'gc'
                },
                'Lock already acquired'
            );
            gcTimeout = setTimeout(clearExpiredMessages, consts.GC_INTERVAL);
            gcTimeout.unref();
            return;
        }

        logger.debug(
            {
                tnx: 'gc'
            },
            'Got lock for garbage collector'
        );

        let done = () => {
            gcLock.releaseLock(lock, err => {
                if (err) {
                    logger.error(
                        {
                            tnx: 'gc',
                            err
                        },
                        'Failed to release lock error=%s',
                        err.message
                    );
                }
                gcTimeout = setTimeout(clearExpiredMessages, consts.GC_INTERVAL);
                gcTimeout.unref();
            });
        };

        if (config.imap.disableRetention) {
            // delete all attachments that do not have any active links to message objects
            // do not touch expired messages
            return messageHandler.attachmentStorage.deleteOrphaned(() => done(null, true));
        }

        let deleteOrphaned = next => {
            // delete all attachments that do not have any active links to message objects
            messageHandler.attachmentStorage.deleteOrphaned(() => {
                next(null, true);
            });
        };

        let archiveExpiredMessages = next => {
            logger.debug(
                {
                    tnx: 'gc'
                },
                'Archiving expired messages'
            );
            // find and delete all messages that are expired
            // NB! scattered query, searches over all mailboxes and thus over all shards
            let cursor = db.database
                .collection('messages')
                .find({
                    exp: true,
                    rdate: {
                        $lte: Date.now()
                    }
                })
                .project({
                    _id: true,
                    mailbox: true,
                    uid: true,
                    size: true,
                    'mimeTree.attachmentMap': true,
                    magic: true,
                    unseen: true
                });

            let deleted = 0;
            let clear = () =>
                cursor.close(() => {
                    if (deleted) {
                        logger.debug(
                            {
                                tnx: 'gc'
                            },
                            'Deleted %s messages',
                            deleted
                        );
                    }
                    return deleteOrphaned(next);
                });

            let processNext = () => {
                if (Date.now() - startTime > consts.GC_INTERVAL * 0.8) {
                    // deleting expired messages has taken too long time, cancel
                    return clear();
                }

                cursor.next((err, messageData) => {
                    if (err) {
                        return done(err);
                    }
                    if (!messageData) {
                        return clear();
                    }

                    messageHandler.del(
                        {
                            messageData,
                            // do not archive messages of deleted users
                            archive: !messageData.userDeleted
                        },
                        err => {
                            if (err) {
                                logger.error(
                                    {
                                        tnx: 'gc',
                                        err
                                    },
                                    'Failed to delete expired message id=%s. %s',
                                    messageData._id,
                                    err.message
                                );
                                return cursor.close(() => done(err));
                            }
                            logger.debug(
                                {
                                    tnx: 'gc',
                                    err
                                },
                                'Deleted expired message id=%s',
                                messageData._id
                            );
                            deleted++;
                            if (consts.GC_DELAY_DELETE) {
                                setTimeout(processNext, consts.GC_DELAY_DELETE);
                            } else {
                                setImmediate(processNext);
                            }
                        }
                    );
                });
            };

            processNext();
        };

        let purgeExpiredMessages = next => {
            logger.debug(
                {
                    tnx: 'gc'
                },
                'Purging archived messages'
            );

            // find and delete all messages that are expired
            // NB! scattered query, searches over all mailboxes and thus over all shards
            let cursor = db.database
                .collection('archived')
                .find({
                    exp: true,
                    rdate: {
                        $lte: Date.now()
                    }
                })
                .project({
                    _id: true,
                    mailbox: true,
                    uid: true,
                    size: true,
                    'mimeTree.attachmentMap': true,
                    'meta.queueId': true,
                    magic: true,
                    unseen: true
                });

            let deleted = 0;
            let clear = () =>
                cursor.close(() => {
                    if (deleted) {
                        logger.debug(
                            {
                                tnx: 'gc'
                            },
                            'Purged %s messages',
                            deleted
                        );
                    }
                    return deleteOrphaned(next);
                });

            let processNext = () => {
                if (Date.now() - startTime > consts.GC_INTERVAL * 0.8) {
                    // deleting expired messages has taken too long time, cancel
                    return clear();
                }

                cursor.next((err, messageData) => {
                    if (err) {
                        return done(err);
                    }
                    if (!messageData) {
                        return clear();
                    }

                    db.database.collection('archived').deleteOne({ _id: messageData._id }, err => {
                        if (err) {
                            //failed to delete
                            logger.error(
                                {
                                    tnx: 'gc',
                                    err
                                },
                                'Failed to delete archived message id=%s. %s',
                                messageData._id,
                                err.message
                            );
                            return cursor.close(() => done(err));
                        }

                        logger.debug(
                            {
                                tnx: 'gc'
                            },
                            'Deleted archived message id=%s',
                            messageData._id
                        );

                        let attachmentIds = Object.keys(messageData.mimeTree.attachmentMap || {}).map(key => messageData.mimeTree.attachmentMap[key]);

                        return db.database.collection('messagelog').insertOne(
                            {
                                id: (messageData.meta && messageData.meta.queueId) || messageData._id.toString(),
                                action: 'DELETED',
                                parentId: messageData._id,
                                created: new Date()
                            },
                            () => {
                                if (!attachmentIds.length) {
                                    // no stored attachments
                                    deleted++;
                                    if (consts.GC_DELAY_DELETE) {
                                        setTimeout(processNext, consts.GC_DELAY_DELETE);
                                    } else {
                                        setImmediate(processNext);
                                    }
                                    return;
                                }

                                messageHandler.attachmentStorage.updateMany(attachmentIds, -1, -messageData.magic, err => {
                                    if (err) {
                                        // should we care about this error?
                                    }
                                    deleted++;
                                    if (consts.GC_DELAY_DELETE) {
                                        setTimeout(processNext, consts.GC_DELAY_DELETE);
                                    } else {
                                        setImmediate(processNext);
                                    }
                                });
                            }
                        );
                    });
                });
            };

            processNext();
        };

        archiveExpiredMessages(() => purgeExpiredMessages(done));
    });
}

let createInterface = (ifaceOptions, callback) => {
    // Setup server
    const serverOptions = {
        secure: ifaceOptions.secure,
        secured: ifaceOptions.secured,

        disableSTARTTLS: ifaceOptions.disableSTARTTLS,
        ignoreSTARTTLS: ifaceOptions.ignoreSTARTTLS,

        useProxy: !!config.imap.useProxy,
        ignoredHosts: config.imap.ignoredHosts,

        id: {
            name: config.imap.name || 'WildDuck IMAP Server',
            version: config.imap.version || packageData.version,
            vendor: config.imap.vendor || 'Kreata'
        },

        logger,

        maxMessage: config.imap.maxMB * 1024 * 1024,
        maxStorage: config.maxStorage * 1024 * 1024
    };

    certs.loadTLSOptions(serverOptions, 'imap');

    const server = new IMAPServer(serverOptions);

    certs.registerReload(server, 'imap');

    let started = false;
    server.on('error', err => {
        if (!started) {
            started = true;
            return callback(err);
        }

        logger.error(
            {
                err
            },
            '%s',
            err.message
        );
    });

    server.indexer = indexer;
    server.notifier = notifier;

    // setup command handlers for the server instance
    server.onFetch = onFetch(server, messageHandler, userHandler.userCache);
    server.onAuth = onAuth(server, userHandler, userHandler.userCache);
    server.onList = onList(server);
    server.onLsub = onLsub(server);
    server.onSubscribe = onSubscribe(server);
    server.onUnsubscribe = onUnsubscribe(server);
    server.onCreate = onCreate(server, mailboxHandler);
    server.onRename = onRename(server, mailboxHandler);
    server.onDelete = onDelete(server, mailboxHandler);
    server.onOpen = onOpen(server);
    server.onStatus = onStatus(server);
    server.onAppend = onAppend(server, messageHandler, userHandler.userCache);
    server.onStore = onStore(server);
    server.onExpunge = onExpunge(server, messageHandler);
    server.onCopy = onCopy(server, messageHandler);
    server.onMove = onMove(server, messageHandler);
    server.onSearch = onSearch(server);
    server.onGetQuotaRoot = onGetQuotaRoot(server);
    server.onGetQuota = onGetQuota(server);

    // start listening
    server.listen(ifaceOptions.port, ifaceOptions.host, () => {
        if (started) {
            return server.close();
        }
        started = true;
        callback(null, server);
    });
};

module.exports = done => {
    if (!config.imap.enabled) {
        return setImmediate(() => done(null, false));
    }

    gcLock = new RedFour({
        redis: db.redis,
        namespace: 'wildduck'
    });

    gcTimeout = setTimeout(clearExpiredMessages, consts.GC_INTERVAL);
    gcTimeout.unref();

    let start = () => {
        indexer = new Indexer({
            database: db.database
        });

        // setup notification system for updates
        notifier = new ImapNotifier({
            database: db.database,
            redis: db.redis
        });

        messageHandler = new MessageHandler({
            database: db.database,
            redis: db.redis,
            gridfs: db.gridfs,
            attachments: config.attachments
        });

        userHandler = new UserHandler({
            database: db.database,
            users: db.users,
            redis: db.redis,
            authlogExpireDays: config.log.authlogExpireDays
        });

        mailboxHandler = new MailboxHandler({
            database: db.database,
            users: db.users,
            redis: db.redis,
            notifier
        });

        let ifaceOptions = [
            {
                enabled: true,
                secure: config.imap.secure,
                disableSTARTTLS: config.imap.disableSTARTTLS,
                ignoreSTARTTLS: config.imap.ignoreSTARTTLS,
                host: config.imap.host,
                port: config.imap.port
            }
        ]
            .concat(config.imap.interface || [])
            .filter(iface => iface.enabled);

        let iPos = 0;
        let startInterfaces = () => {
            if (iPos >= ifaceOptions.length) {
                return done();
            }
            let opts = ifaceOptions[iPos++];

            createInterface(opts, err => {
                if (err) {
                    logger.error(
                        {
                            err,
                            tnx: 'bind'
                        },
                        'Failed starting %sIMAP interface %s:%s. %s',
                        opts.secure ? 'secure ' : '',
                        opts.host,
                        opts.port,
                        err.message
                    );
                    return done(err);
                }
                setImmediate(startInterfaces);
            });
        };
        setImmediate(startInterfaces);
    };

    let collections = setupIndexes.collections;
    let collectionpos = 0;
    let ensureCollections = next => {
        if (collectionpos >= collections.length) {
            logger.info(
                {
                    tnx: 'mongo'
                },
                'Setup %s collections',
                collections.length
            );
            return next();
        }
        let collection = collections[collectionpos++];
        db[collection.type || 'database'].createCollection(collection.collection, collection.options, err => {
            if (err) {
                logger.error(
                    {
                        err,
                        tnx: 'mongo'
                    },
                    'Failed creating collection %s %s. %s',
                    collectionpos,
                    JSON.stringify(collection.collection),
                    err.message
                );
            }

            ensureCollections(next);
        });
    };

    let indexes = setupIndexes.indexes;
    let indexpos = 0;
    let ensureIndexes = next => {
        if (indexpos >= indexes.length) {
            logger.info(
                {
                    tnx: 'mongo'
                },
                'Setup indexes for %s collections',
                indexes.length
            );
            return next();
        }
        let index = indexes[indexpos++];
        db[index.type || 'database'].collection(index.collection).createIndexes([index.index], (err, r) => {
            if (err) {
                logger.error(
                    {
                        err,
                        tnx: 'mongo'
                    },
                    'Failed creating index %s %s. %s',
                    indexpos,
                    JSON.stringify(index.collection + '.' + index.index.name),
                    err.message
                );
            } else if (r.numIndexesAfter !== r.numIndexesBefore) {
                logger.debug(
                    {
                        tnx: 'mongo'
                    },
                    'Created index %s %s',
                    indexpos,
                    JSON.stringify(index.collection + '.' + index.index.name)
                );
            } else {
                logger.debug(
                    {
                        tnx: 'mongo'
                    },
                    'Skipped index %s %s: %s',
                    indexpos,
                    JSON.stringify(index.collection + '.' + index.index.name),
                    r.note || 'No index added'
                );
            }

            ensureIndexes(next);
        });
    };

    gcLock.acquireLock('db_indexes', 1 * 60 * 1000, (err, lock) => {
        if (err) {
            logger.error(
                {
                    tnx: 'gc',
                    err
                },
                'Failed to acquire lock error=%s',
                err.message
            );
            return start();
        } else if (!lock.success) {
            return start();
        }

        ensureCollections(() => {
            ensureIndexes(() => {
                // Do not release the indexing lock immediatelly
                setTimeout(() => {
                    gcLock.releaseLock(lock, err => {
                        if (err) {
                            logger.error(
                                {
                                    tnx: 'gc',
                                    err
                                },
                                'Failed to release lock error=%s',
                                err.message
                            );
                        }
                    });
                }, 60 * 1000);
                return start();
            });
        });
    });
};