'use strict';

exports = module.exports = {
    isMountProvider,
    tryAddMount,
    removeMount,
    validateMountOptions,
    getStatus,
};

const assert = require('assert'),
    BoxError = require('./boxerror.js'),
    constants = require('./constants.js'),
    debug = require('debug')('box:mounts'),
    ejs = require('ejs'),
    fs = require('fs'),
    path = require('path'),
    paths = require('./paths.js'),
    safe = require('safetydance'),
    shell = require('./shell.js');

const ADD_MOUNT_CMD = path.join(__dirname, 'scripts/addmount.sh');
const RM_MOUNT_CMD = path.join(__dirname, 'scripts/rmmount.sh');
const SYSTEMD_MOUNT_EJS = fs.readFileSync(path.join(__dirname, 'systemd-mount.ejs'), { encoding: 'utf8' });

// https://man7.org/linux/man-pages/man8/mount.8.html
function validateMountOptions(type, options) {
    assert.strictEqual(typeof type, 'string');
    assert.strictEqual(typeof options, 'object');

    switch (type) {
    case 'filesystem':
    case 'mountpoint':
        return null;
    case 'cifs':
        if (typeof options.username !== 'string') return new BoxError(BoxError.BAD_FIELD, 'username is not a string');
        if (typeof options.password !== 'string') return new BoxError(BoxError.BAD_FIELD, 'password is not a string');
        if (typeof options.host !== 'string') return new BoxError(BoxError.BAD_FIELD, 'host is not a string');
        if (typeof options.remoteDir !== 'string') return new BoxError(BoxError.BAD_FIELD, 'remoteDir is not a string');
        return null;
    case 'nfs':
        if (typeof options.host !== 'string') return new BoxError(BoxError.BAD_FIELD, 'host is not a string');
        if (typeof options.remoteDir !== 'string') return new BoxError(BoxError.BAD_FIELD, 'remoteDir is not a string');
        return null;
    case 'sshfs':
        if (typeof options.user !== 'string') return new BoxError(BoxError.BAD_FIELD, 'user is not a string');
        if (typeof options.privateKey !== 'string') return new BoxError(BoxError.BAD_FIELD, 'privateKey is not a string');
        if (typeof options.port !== 'number') return new BoxError(BoxError.BAD_FIELD, 'port is not a number');
        if (typeof options.host !== 'string') return new BoxError(BoxError.BAD_FIELD, 'host is not a string');
        if (typeof options.remoteDir !== 'string') return new BoxError(BoxError.BAD_FIELD, 'remoteDir is not a string');
        return null;
    case 'ext4':
        if (typeof options.diskPath !== 'string') return new BoxError(BoxError.BAD_FIELD, 'diskPath is not a string');
        return null;
    default:
        return new BoxError(BoxError.BAD_FIELD, 'Bad mount type');
    }
}

function isMountProvider(provider) {
    return provider === 'sshfs' || provider === 'cifs' || provider === 'nfs' || provider === 'ext4';
}

// https://www.man7.org/linux/man-pages/man8/mount.8.html for various mount option flags
// nfs - no_root_squash is mode on server to map all root to 'nobody' user. all_squash does this for all users (making it like ftp)
// sshfs - supports users/permissions
// cifs - does not support permissions
function renderMountFile(mount) {
    assert.strictEqual(typeof mount, 'object');

    const {name, hostPath, mountType, mountOptions} = mount;

    let options, what, type;
    switch (mountType) {
    case 'cifs':
        type = 'cifs';
        what = `//${mountOptions.host}` + path.join('/', mountOptions.remoteDir);
        options = `username=${mountOptions.username},password=${mountOptions.password},rw,iocharset=utf8,file_mode=0666,dir_mode=0777,uid=yellowtent,gid=yellowtent`;
        break;
    case 'nfs':
        type = 'nfs';
        what = `${mountOptions.host}:${mountOptions.remoteDir}`;
        options = 'noauto'; // noauto means it is not a blocker for local-fs.target. _netdev is implicit. rw,hard,tcp,rsize=8192,wsize=8192,timeo=14
        break;
    case 'ext4':
        type = 'ext4';
        what = mountOptions.diskPath; // like /dev/disk/by-uuid/uuid or /dev/disk/by-id/scsi-id
        options = 'discard,defaults,noatime';
        break;
    case 'sshfs': {
        const keyFilePath = path.join(paths.SSHFS_KEYS_DIR, `id_rsa_${mountOptions.host}`);
        type = 'fuse.sshfs';
        what = `${mountOptions.user}@${mountOptions.host}:${mountOptions.remoteDir}`;
        options = `allow_other,port=${mountOptions.port},IdentityFile=${keyFilePath},StrictHostKeyChecking=no,reconnect`; // allow_other means non-root users can access it
        break;
    }
    case 'filesystem':
    case 'mountpoint':
        return;
    }

    return ejs.render(SYSTEMD_MOUNT_EJS, { name, what, where: hostPath, options, type });
}

async function removeMount(mount) {
    assert.strictEqual(typeof mount, 'object');

    const { hostPath, mountType, mountOptions } = mount;

    if (constants.TEST) return;

    await safe(shell.promises.sudo('removeMount', [ RM_MOUNT_CMD, hostPath ], {}), { debug }); // ignore any error

    if (mountType === 'sshfs') {
        const keyFilePath = path.join(paths.SSHFS_KEYS_DIR, `id_rsa_${mountOptions.host}`);
        safe.fs.unlinkSync(keyFilePath);
    }
}

async function getStatus(mountType, hostPath) {
    assert.strictEqual(typeof mountType, 'string');
    assert.strictEqual(typeof hostPath, 'string');

    if (mountType === 'filesystem') return { state: 'active', message: 'Mounted' };

    const state = safe.child_process.execSync(`mountpoint -q -- ${hostPath}`) ? 'active' : 'inactive';

    if (mountType === 'mountpoint') return { state, message: state === 'active' ? 'Mounted' : 'Not mounted' };

    // we used to rely on "systemctl show -p ActiveState" output before but some mounts like sshfs.fuse show the status as "active" event though the mount commant failed (on ubuntu 18)
    let message;

    if (state !== 'active') { // find why it failed
        const logsJson = safe.child_process.execSync(`journalctl -u $(systemd-escape -p --suffix=mount ${hostPath}) -n 10 --no-pager -o json`, { encoding: 'utf8' });

        if (logsJson) {
            const lines = logsJson.trim().split('\n').map(l => JSON.parse(l)); // array of json
            let start = -1, end = -1; // start and end of error message block
            for (let idx = lines.length - 1; idx >= 0; idx--) { // reverse
                const line = lines[idx];
                const match = line['SYSLOG_IDENTIFIER'] === 'mount' || line['_EXE'].includes('mount') || line['_COMM'].includes('mount');
                if (match) {
                    if (end === -1) end = idx;
                    start = idx;
                    continue;
                }

                if (end !== -1) break; // no match and we already found a block
            }

            if (end !== -1) message = lines.slice(start, end+1).map(line => line['MESSAGE']).join('\n');
        }
        if (!message) message = `Could not determine failure reason. ${safe.error ? safe.error.message : ''}`;
    } else {
        message = 'Mounted';
    }

    return { state, message };
}

async function tryAddMount(mount, options) {
    assert.strictEqual(typeof mount, 'object'); // { name, hostPath, mountType, mountOptions }
    assert.strictEqual(typeof options, 'object'); // { timeout, skipCleanup }

    if (mount.mountType === 'mountpoint') return;

    if (constants.TEST) return;

    if (mount.mountType === 'sshfs') {
        const keyFilePath = path.join(paths.SSHFS_KEYS_DIR, `id_rsa_${mount.mountOptions.host}`);

        safe.fs.mkdirSync(paths.SSHFS_KEYS_DIR);
        if (!safe.fs.writeFileSync(keyFilePath, `${mount.mountOptions.privateKey}\n`, { mode: 0o600 })) throw new BoxError(BoxError.FS_ERROR, safe.error);
    }

    const [error] = await safe(shell.promises.sudo('addMount', [ ADD_MOUNT_CMD, renderMountFile(mount), options.timeout ], {}));
    if (error && error.code === 2) throw new BoxError(BoxError.MOUNT_ERROR, 'Failed to unmount existing mount'); // at this point, the old mount config is still there

    if (options.skipCleanup) return;

    const status = await getStatus(mount.mountType, mount.hostPath);
    if (status.state !== 'active') {  // cleanup
        await removeMount(mount);
        throw new BoxError(BoxError.MOUNT_ERROR, `Failed to mount (${status.state}): ${status.message}`);
    }
}