'use strict';

exports = module.exports = {
    download,
    upload,
    verify,
    getFileExtension,
    copy,

    _saveFsMetadata: saveFsMetadata,
    _restoreFsMetadata: restoreFsMetadata
};

const assert = require('node:assert'),
    async = require('async'),
    backupSites = require('../backupsites.js'),
    BoxError = require('../boxerror.js'),
    DataLayout = require('../datalayout.js'),
    { DecryptStream } = require('../hush.js'),
    debug = require('debug')('box:backupformat/rsync'),
    { EncryptStream } = require('../hush.js'),
    fs = require('node:fs'),
    HashStream = require('../hash-stream.js'),
    hush = require('../hush.js'),
    path = require('node:path'),
    paths = require('../paths.js'),
    ProgressStream = require('../progress-stream.js'),
    promiseRetry = require('../promise-retry.js'),
    safe = require('safetydance'),
    shell = require('../shell.js')('backupformat/rsync'),
    stream = require('stream/promises'),
    syncer = require('../syncer.js'),
    util = require('node:util');

async function addFile(sourceFile, encryption, uploader, progressCallback) {
    assert.strictEqual(typeof sourceFile, 'string');
    assert.strictEqual(typeof encryption, 'object');
    assert.strictEqual(typeof uploader, 'object');
    assert.strictEqual(typeof progressCallback, 'function');

    // make sure file can be opened for reading before we start the pipeline. otherwise, we end up with
    // destinations dirs/file which are owned by root (this process id) and cannot be copied (run as normal user)
    const [openError, sourceHandle] = await safe(fs.promises.open(sourceFile, 'r'));
    if (openError) {
        debug(`addFile: ignoring disappeared file: ${sourceFile}`);
        return null;
    }

    const sourceStream = sourceHandle.createReadStream(sourceFile, { autoClose: true });
    const ps = new ProgressStream({ interval: 10000 }); // display a progress every 10 seconds
    ps.on('progress', function (progress) {
        const transferred = Math.round(progress.transferred/1024/1024), speed = Math.round(progress.speed/1024/1024);
        if (!transferred && !speed) return progressCallback({ message: `Uploading ${sourceFile}` }); // 0M@0MBps looks wrong
        progressCallback({ message: `Uploading ${sourceFile}: ${transferred}M@${speed}MBps` }); // 0M@0MBps looks wrong
    });

    const hash = new HashStream();

    let pipeline = null;
    if (encryption) {
        const encryptStream = new EncryptStream(encryption);
        pipeline = safe(stream.pipeline(sourceStream, encryptStream, ps, hash, uploader.stream));
    } else {
        pipeline = safe(stream.pipeline(sourceStream, ps, hash, uploader.stream));
    }

    const [error] = await safe(pipeline);
    if (error && !error.message.includes('ENOENT')) throw new BoxError(BoxError.EXTERNAL_ERROR, `tarPack pipeline error: ${error.message}`); // ignore error if file disappears
    // debug(`addFile: pipeline finished: ${JSON.stringify(ps.stats())}`);

    await uploader.finish();

    return {
        stats: ps.stats(),
        integrity: { size: ps.stats().transferred, sha256: hash.digest('hex') }
    };
}

async function sync(backupSite, remotePath, dataLayout, progressCallback) {
    assert.strictEqual(typeof backupSite, 'object');
    assert.strictEqual(typeof remotePath, 'string');
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof progressCallback, 'function');

    // the number here has to take into account the s3.upload partSize (which is 10MB). So 20=200MB
    const concurrency = backupSite.limits?.syncConcurrency || (backupSite.provider === 's3' ? 20 : 10);
    const cacheFile = path.join(paths.BACKUP_INFO_DIR, backupSite.id, `${dataLayout.getBasename()}.sync.cache`);
    const { delQueue, addQueue, integrityMap } = await syncer.sync(dataLayout, cacheFile); // integrityMap is unchanged files
    debug(`sync: processing ${delQueue.length} deletes and ${addQueue.length} additions`);
    const aggregatedStats = {
        transferred: 0,
        size: [...integrityMap.values()].reduce((sum, { size }) => sum + size, 0),
        fileCount: addQueue.length + integrityMap.size, // final file count, not the transferred file count
        startTime: Date.now(),
        totalMsecs: 0
    };

    async function processSyncerChange(change) {
        debug('sync: processing task: %j', change);
        // the empty task.path is special to signify the directory
        const destPath = change.path && backupSite.encryption?.encryptedFilenames ? hush.encryptFilePath(change.path, backupSite.encryption) : change.path;
        const fullPath = path.join(remotePath, destPath);

        if (change.operation === 'removedir') {
            debug(`Removing directory ${fullPath}`);
            await backupSites.storageApi(backupSite).removeDir(backupSite.config, fullPath, progressCallback);
        } else if (change.operation === 'remove') {
            debug(`Removing ${fullPath}`);
            await backupSites.storageApi(backupSite).remove(backupSite.config, fullPath);
        } else if (change.operation === 'add') {
            await promiseRetry({ times: 5, interval: 20000, debug }, async (retryCount) => {
                progressCallback({ message: `Adding ${change.path}` + (retryCount > 1 ?  ` (Try ${retryCount})` : '') });
                debug(`Adding ${change.path} position ${change.position} try ${retryCount}`);

                const uploader = await backupSites.storageApi(backupSite).upload(backupSite.config, fullPath);
                const result = await addFile(dataLayout.toLocalPath('./' + change.path), backupSite.encryption, uploader, progressCallback);
                if (!result) return; // this can happen if the file disappeared on us
                integrityMap.set(destPath, result.integrity);
                aggregatedStats.transferred += result.stats.transferred;
                aggregatedStats.size += result.stats.transferred;
            });
        }
    }

    const [delError] = await safe(async.eachLimit(delQueue, concurrency, async (change) => await processSyncerChange(change, backupSite, remotePath, dataLayout, progressCallback)));
    debug('sync: done processing deletes. error: %o', delError);
    if (delError) throw delError;

    const [addError] = await safe(async.eachLimit(addQueue, concurrency, async (change) => await processSyncerChange(change, backupSite, remotePath, dataLayout, progressCallback)));
    debug('sync: done processing adds. error: %o', addError);
    if (addError) throw addError;

    await syncer.finalize(integrityMap, cacheFile);

    return {
        stats: { ...aggregatedStats, totalMsecs: Date.now()-aggregatedStats.startTime },
        integrityMap
    };
}

// this is not part of 'snapshotting' because we need root access to traverse
async function saveFsMetadata(dataLayout, metadataFile) {
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof metadataFile, 'string');

    // contains paths prefixed with './'
    const metadata = {
        emptyDirs: [],
        execFiles: [],
        symlinks: []
    };

    // we assume small number of files. spawnSync will raise a ENOBUFS error after maxBuffer
    for (const lp of dataLayout.localPaths()) {
        const [emptyDirsError, emptyDirs] = await safe(shell.spawn('find', [lp, '-type', 'd', '-empty'], { encoding: 'utf8', maxLines: 50000 }));
        if (emptyDirsError && emptyDirsError.stdoutLineCount >= 50000) throw new BoxError(BoxError.FS_ERROR, `Too many empty directories. Run "find ${lp} -type d -empty" to investigate`);
        if (emptyDirsError) throw emptyDirsError;
        if (emptyDirs.length) metadata.emptyDirs = metadata.emptyDirs.concat(emptyDirs.trim().split('\n').map((ed) => dataLayout.toRemotePath(ed)));

        const [execFilesError, execFiles] = await safe(shell.spawn('find', [lp, '-type', 'f', '-executable'], { encoding: 'utf8', maxLines: 20000 }));
        if (execFilesError && execFilesError.stdoutLineCount >= 20000) throw new BoxError(BoxError.FS_ERROR, `Too many executable files. Run "find ${lp} -type f -executable" to investigate`);
        if (execFilesError) throw execFilesError;
        if (execFiles.length) metadata.execFiles = metadata.execFiles.concat(execFiles.trim().split('\n').map((ef) => dataLayout.toRemotePath(ef)));

        const [symlinkFilesError, symlinkFiles] = await safe(shell.spawn('find', [lp, '-type', 'l'], { encoding: 'utf8', maxLines: 20000 }));
        if (symlinkFilesError && symlinkFilesError.stdoutLineCount >= 20000) throw new BoxError(BoxError.FS_ERROR, `Too many symlinks. Run "find ${lp} -type l" to investigate`);
        if (symlinkFilesError) throw symlinkFilesError;

        if (symlinkFiles.length) metadata.symlinks = metadata.symlinks.concat(symlinkFiles.trim().split('\n').map((sl) => {
            const site = safe.fs.readlinkSync(sl);
            return { path: dataLayout.toRemotePath(sl), site };
        }));
    }

    if (!safe.fs.writeFileSync(metadataFile, JSON.stringify(metadata, null, 2))) throw new BoxError(BoxError.FS_ERROR, `Error writing fs metadata: ${safe.error.message}`);
}

async function restoreFsMetadata(dataLayout, metadataFile) {
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof metadataFile, 'string');

    debug(`Recreating empty directories in ${dataLayout.toString()}`);

    const metadataJson = safe.fs.readFileSync(metadataFile, 'utf8');
    if (metadataJson === null) throw new BoxError(BoxError.EXTERNAL_ERROR, 'Error loading fsmetadata.json:' + safe.error.message);
    const metadata = safe.JSON.parse(metadataJson);
    if (metadata === null) throw new BoxError(BoxError.EXTERNAL_ERROR, 'Error parsing fsmetadata.json:' + safe.error.message);

    for (const emptyDir of metadata.emptyDirs) {
        const [mkdirError] = await safe(fs.promises.mkdir(dataLayout.toLocalPath(emptyDir), { recursive: true }));
        if (mkdirError) throw new BoxError(BoxError.FS_ERROR, `unable to create path: ${mkdirError.message}`);
    }

    for (const execFile of metadata.execFiles) {
        const [chmodError] = await safe(fs.promises.chmod(dataLayout.toLocalPath(execFile), parseInt('0755', 8)));
        if (chmodError) throw new BoxError(BoxError.FS_ERROR, `unable to chmod: ${chmodError.message}`);
    }

    for (const symlink of (metadata.symlinks || [])) {
        if (!symlink.site) continue;
        // the path may not exist if we had a directory full of symlinks
        const [mkdirError] = await safe(fs.promises.mkdir(path.dirname(dataLayout.toLocalPath(symlink.path)), { recursive: true }));
        if (mkdirError) throw new BoxError(BoxError.FS_ERROR, `unable to symlink (mkdir): ${mkdirError.message}`);
        const [symlinkError] = await safe(fs.promises.symlink(symlink.site, dataLayout.toLocalPath(symlink.path), 'file'));
        if (symlinkError) throw new BoxError(BoxError.FS_ERROR, `unable to symlink: ${symlinkError.message}`);
    }
}

async function downloadDir(backupSite, remotePath, dataLayout, progressCallback) {
    assert.strictEqual(typeof backupSite, 'object');
    assert.strictEqual(typeof remotePath, 'string');
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof progressCallback, 'function');

    const encryptedFilenames = backupSite.encryption?.encryptedFilenames || false;

    debug(`downloadDir: ${remotePath} to ${dataLayout.toString()}. encryption filenames: ${encryptedFilenames}. encrypted files: ${!!backupSite.encryption}`);

    async function downloadFile(entry) {
        let relativePath = path.relative(remotePath, entry.path);
        if (encryptedFilenames) {
            const { error, result } = hush.decryptFilePath(relativePath, backupSite.encryption);
            if (error) throw new BoxError(BoxError.CRYPTO_ERROR, 'Unable to decrypt file');
            relativePath = result;
        }
        const destFilePath = dataLayout.toLocalPath('./' + relativePath);

        const [mkdirError] = await safe(fs.promises.mkdir(path.dirname(destFilePath), { recursive: true }));
        if (mkdirError) throw new BoxError(BoxError.FS_ERROR, mkdirError.message);

        await promiseRetry({ times: 3, interval: 20000 }, async function () {
            progressCallback({ message: `Downloading ${entry.path} to ${destFilePath}` });

            const [downloadError, sourceStream] = await safe(backupSites.storageApi(backupSite).download(backupSite.config, entry.path));
            if (downloadError) {
                progressCallback({ message: `Download ${entry.path} to ${destFilePath} errored: ${downloadError.message}` });
                throw downloadError;
            }

            const ps = new ProgressStream({ interval: 10000 }); // display a progress every 10 seconds
            ps.on('progress', function (progress) {
                const transferred = Math.round(progress.transferred/1024/1024), speed = Math.round(progress.speed/1024/1024);
                if (!transferred && !speed) return progressCallback({ message: `Downloading ${entry.path}` }); // 0M@0MBps looks wrong
                progressCallback({ message: `Downloading ${entry.path}: ${transferred}M@${speed}MBps` });
            });

            const destStream = fs.createWriteStream(destFilePath);

            const streams = [ sourceStream, ps ];

            if (backupSite.encryption) {
                const decryptStream = new DecryptStream(backupSite.encryption);
                streams.push(decryptStream);
            }

            streams.push(destStream);

            const [pipelineError] = await safe(stream.pipeline(streams));
            if (pipelineError) {
                progressCallback({ message: `Download error ${entry.path} to ${destFilePath}: ${pipelineError.message}` });
                throw pipelineError;
            }
            progressCallback({ message: `Download finished ${entry.path} to ${destFilePath}` });
        });
    }

    // https://www.digitalocean.com/community/questions/rate-limiting-on-spaces?answer=40441
    const concurrency = backupSite.limits?.downloadConcurrency || (backupSite.provider === 's3' ? 30 : 10);
    let marker = null;
    while (true) {
        const batch = await backupSites.storageApi(backupSite).listDir(backupSite.config, remotePath, marker === null ? 1 : 1000, marker); // try with one file first. if that works out, we continue faster
        await async.eachLimit(batch.entries, concurrency, downloadFile);
        if (!batch.marker) break;
        marker = batch.marker;
    }
}

async function download(backupSite, remotePath, dataLayout, progressCallback) {
    assert.strictEqual(typeof backupSite, 'object');
    assert.strictEqual(typeof remotePath, 'string');
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof progressCallback, 'function');

    debug(`download: Downloading ${remotePath} to ${dataLayout.toString()}`);

    await downloadDir(backupSite, remotePath, dataLayout, progressCallback);
    await restoreFsMetadata(dataLayout, `${dataLayout.localRoot()}/fsmetadata.json`);
}

async function upload(backupSite, remotePath, dataLayout, progressCallback) {
    assert.strictEqual(typeof backupSite, 'object');
    assert.strictEqual(typeof remotePath, 'string');
    assert.strictEqual(typeof dataLayout, 'object');
    assert.strictEqual(typeof progressCallback, 'function');

    debug(`upload: uploading to site ${backupSite.id} path ${remotePath} (encrypted: ${!!backupSite.encryption}) dataLayout ${dataLayout.toString()}`);

    await saveFsMetadata(dataLayout, `${dataLayout.localRoot()}/fsmetadata.json`);
    return await sync(backupSite, remotePath, dataLayout, progressCallback); // { stats, integrityMap }
}

async function copy(backupSite, fromPath, toPath, progressCallback) {
    assert.strictEqual(typeof backupSite, 'object');
    assert.strictEqual(typeof fromPath, 'string');
    assert.strictEqual(typeof toPath, 'string');
    assert.strictEqual(typeof progressCallback, 'function');

    await backupSites.storageApi(backupSite).copyDir(backupSite.config, fromPath, toPath, progressCallback);
}

function getFileExtension(encryption) {
    assert.strictEqual(typeof encryption, 'boolean');

    return ''; // this also signals to backupcleanear that we are dealing with directories
}

async function verify(backupSite, remotePath, integrityMap, progressCallback) {
    assert.strictEqual(typeof backupSite, 'object');
    assert.strictEqual(typeof remotePath, 'string');
    assert(util.types.isMap(integrityMap), 'integrityMap should be a Map');
    assert.strictEqual(typeof progressCallback, 'function');

    debug(`verify: Verifying ${remotePath}`);

    const encryptedFilenames = backupSite.encryption?.encryptedFilenames || false;
    let fileCount = 0;

    async function validateFile(entry) {
        let relativePath = path.relative(remotePath, entry.path);
        if (encryptedFilenames) {
            const { error, result } = hush.decryptFilePath(relativePath, backupSite.encryption);
            if (error) throw new BoxError(BoxError.CRYPTO_ERROR, 'Unable to decrypt file');
            relativePath = result;
        }

        ++fileCount;
        const sourceStream = await backupSites.storageApi(backupSite).download(backupSite.config, entry.path);

        const ps = new ProgressStream({ interval: 10000 }); // display a progress every 10 seconds
        ps.on('progress', function (progress) {
            const transferred = Math.round(progress.transferred/1024/1024), speed = Math.round(progress.speed/1024/1024);
            if (!transferred && !speed) return progressCallback({ message: `Downloading ${entry.path}` }); // 0M@0MBps looks wrong
            progressCallback({ message: `Downloading ${entry.path}: ${transferred}M@${speed}MBps` });
        });

        const streams = [ sourceStream, ps ];

        if (backupSite.encryption) {
            const decryptStream = new DecryptStream(backupSite.encryption);
            streams.push(decryptStream);
        }

        const hash = new HashStream();
        streams.push(hash);

        await stream.pipeline(streams);

        const integrity = integrityMap.get(relativePath);
        if (ps.stats().transferred !== integrity.size) throw new BoxError(BoxError.BAD_STATE, `${entry.path} has size ${ps.stats().transferred}. Expecting ${integrity.size}`);
        if (hash.digest() !== integrity.sha256) throw new BoxError(BoxError.BAD_STATE, `${entry.path} has size ${hash.digest()}. Expecting ${integrity.sha256}`);
    }

    debug(integrityMap.entries());

    // https://www.digitalocean.com/community/questions/rate-limiting-on-spaces?answer=40441
    const concurrency = backupSite.limits?.downloadConcurrency || (backupSite.provider === 's3' ? 30 : 10);
    let marker = null;
    while (true) {
        const batch = await backupSites.storageApi(backupSite).listDir(backupSite.config, remotePath, marker === null ? 1 : 1000, marker); // try with one file first. if that works out, we continue faster
        await async.eachLimit(batch.entries, concurrency, validateFile);
        if (!batch.marker) break;
        marker = batch.marker;
    }

    const check = (x, y) => { return x === y ? { status: 'passed' } : { status: 'failed', message: `Expecting ${x} but got ${y}` }; };

    if (integrityMap.size !== fileCount) throw new BoxError(BoxError.BAD_STATE, `Got ${fileCount} files. Expecting ${integrityMap.size()} files`);

    return {
        size: { status: 'passed' },
        fileCount: check(integrityMap.size, fileCount),
        sha256: { status: 'passed' },
    };
}