// Native
const { resolve } = require('path');

// Packages
const flatten = require('arr-flatten');
const unique = require('array-unique');
const ignore = require('ignore');
const _glob = require('glob');
const { stat, readdir, readFile } = require('fs-promise');

// Ours
const IGNORED = require('./ignored');

const glob = async function(pattern, options) {
  return new Promise((resolve, reject) => {
    _glob(pattern, options, (error, files) => {
      if (error) {
        reject(error);
      } else {
        resolve(files);
      }
    });
  });
};

/**
 * Remove leading `./` from the beginning of ignores
 * because our parser doesn't like them :|
 */

const clearRelative = function(str) {
  return str.replace(/(\n|^)\.\//g, '$1');
};

/**
 * Returns the contents of a file if it exists.
 *
 * @return {String} results or `''`
 */

const maybeRead = async function(path, default_ = '') {
  try {
    return await readFile(path, 'utf8');
  } catch (err) {
    return default_;
  }
};

/**
 * Transform relative paths into absolutes,
 * and maintains absolutes as such.
 *
 * @param {String} maybe relative path
 * @param {String} parent full path
 */

const asAbsolute = function(path, parent) {
  if (path[0] === '/') {
    return path;
  }

  return resolve(parent, path);
};

/**
 * Returns a list of files in the given
 * directory that are subject to be
 * synchronized for npm.
 *
 * @param {String} full path to directory
 * @param {String} contents of `package.json` to avoid lookup
 * @param {Object} options:
 *  - `limit` {Number|null} byte limit
 *  - `debug` {Boolean} warn upon ignore
 * @return {Array} comprehensive list of paths to sync
 */

async function npm(
  path,
  pkg,
  nowConfig = null,
  {
    limit = null,
    hasNowJson = false,
    debug = false
  } = {}
) {
  const whitelist = (nowConfig && nowConfig.files) || pkg.files;

  // The package.json `files` whitelist still
  // honors ignores: https://docs.npmjs.com/files/package.json#files
  const search_ = whitelist || ['.'];
  // Convert all filenames into absolute paths
  const search = Array.prototype.concat.apply(
    [],
    await Promise.all(
      search_.map(file => glob(file, { cwd: path, absolute: true, dot: true }))
    )
  );

  // Compile list of ignored patterns and files
  const npmIgnore = await maybeRead(resolve(path, '.npmignore'), null);
  const gitIgnore = npmIgnore === null
    ? await maybeRead(resolve(path, '.gitignore'))
    : null;

  const filter = ignore()
    .add(
      IGNORED + '\n' + clearRelative(npmIgnore === null ? gitIgnore : npmIgnore)
    )
    .createFilter();

  const prefixLength = path.length + 1;

  // The package.json `files` whitelist still
  // honors npmignores: https://docs.npmjs.com/files/package.json#files
  // but we don't ignore if the user is explicitly listing files
  // under the now namespace, or using files in combination with gitignore
  const overrideIgnores = (pkg.now && pkg.now.files) ||
    (gitIgnore !== null && pkg.files);
  const accepts = overrideIgnores
    ? () => true
    : file => {
        const relativePath = file.substr(prefixLength);

        if (relativePath === '') {
          return true;
        }

        const accepted = filter(relativePath);
        if (!accepted && debug) {
          console.log('> [debug] ignoring "%s"', file);
        }
        return accepted;
      };

  // Locate files
  if (debug) {
    console.time(`> [debug] locating files ${path}`);
  }

  const files = await explode(search, {
    accepts,
    limit,
    debug
  });

  if (debug) {
    console.timeEnd(`> [debug] locating files ${path}`);
  }

  // Always include manifest as npm does not allow ignoring it
  // source: https://docs.npmjs.com/files/package.json#files
  files.push(asAbsolute('package.json', path));

  if (hasNowJson) {
    files.push(asAbsolute('now.json', path));
  }

  // Get files
  return unique(files);
}

/**
 * Returns a list of files in the given
 * directory that are subject to be
 * sent to docker as build context.
 *
 * @param {String} full path to directory
 * @param {String} contents of `Dockerfile`
 * @param {Object} options:
 *  - `limit` {Number|null} byte limit
 *  - `debug` {Boolean} warn upon ignore
 * @return {Array} comprehensive list of paths to sync
 */

async function docker(
  path,
  nowConfig = null,
  {
    limit = null,
    hasNowJson = false,
    debug = false
  } = {}
) {
  const whitelist = nowConfig && nowConfig.files;

  // Base search path
  // the now.json `files` whitelist still
  // honors ignores: https://docs.npmjs.com/files/package.json#files
  const search_ = whitelist || ['.'];

  // Convert all filenames into absolute paths
  const search = search_.map(file => asAbsolute(file, path));

  // Compile list of ignored patterns and files
  const dockerIgnore = await maybeRead(resolve(path, '.dockerignore'), null);

  const filter = ignore()
    .add(
      IGNORED +
        '\n' +
        clearRelative(
          dockerIgnore === null
            ? await maybeRead(resolve(path, '.gitignore'))
            : dockerIgnore
        )
    )
    .createFilter();

  const prefixLength = path.length + 1;
  const accepts = function(file) {
    const relativePath = file.substr(prefixLength);

    if (relativePath === '') {
      return true;
    }

    const accepted = filter(relativePath);
    if (!accepted && debug) {
      console.log('> [debug] ignoring "%s"', file);
    }
    return accepted;
  };

  // Locate files
  if (debug) {
    console.time(`> [debug] locating files ${path}`);
  }

  const files = await explode(search, { accepts, limit, debug });

  if (debug) {
    console.timeEnd(`> [debug] locating files ${path}`);
  }

  // Always include manifest as npm does not allow ignoring it
  // source: https://docs.npmjs.com/files/package.json#files
  files.push(asAbsolute('Dockerfile', path));

  if (hasNowJson) {
    files.push(asAbsolute('now.json', path));
  }

  // Get files
  return unique(files);
}

/**
 * Explodes directories into a full list of files.
 * Eg:
 *   in:  ['/a.js', '/b']
 *   out: ['/a.js', '/b/c.js', '/b/d.js']
 *
 * @param {Array} of {String}s representing paths
 * @param {Array} of ignored {String}s.
 * @param {Object} options:
 *  - `limit` {Number|null} byte limit
 *  - `debug` {Boolean} warn upon ignore
 * @return {Array} of {String}s of full paths
 */

async function explode(paths, { accepts, debug }) {
  const list = async file => {
    let path = file;
    let s;

    if (!accepts(file)) {
      return null;
    }

    try {
      s = await stat(path);
    } catch (e) {
      // In case the file comes from `files`
      // and it wasn't specified with `.js` by the user
      path = file + '.js';

      try {
        s = await stat(path);
      } catch (e2) {
        if (debug) {
          console.log('> [debug] ignoring invalid file "%s"', file);
        }
        return null;
      }
    }

    if (s.isDirectory()) {
      const all = await readdir(file);
      /* eslint-disable no-use-before-define */
      return many(all.map(subdir => asAbsolute(subdir, file)));
      /* eslint-enable no-use-before-define */
    } else if (!s.isFile()) {
      if (debug) {
        console.log('> [debug] ignoring special file "%s"', file);
      }
      return null;
    }

    return path;
  };

  const many = all => Promise.all(all.map(file => list(file)));
  return flatten(await many(paths)).filter(v => v !== null);
}

module.exports = {
  npm,
  docker
};