'use strict';

const path = require('path');

const Promise = require('bluebird');

const fs = Promise.promisifyAll(require('fs'));

const globby = require('globby');

const debug = require('debug')('purs-loader');

const srcModuleRegex = /(?:^|\n)module\s+([\w\.]+)/i;

const importModuleRegex = /(?:^|\n)\s*import\s+([\w\.]+)/ig;

module.exports.matchModule = function matchModule(str) {
  const matches = str.match(srcModuleRegex);
  return matches && matches[1];
};

module.exports.matchImports = function matchImports(str) {
  const matches = str.match(importModuleRegex);
  return (matches || []).map(a => a.replace(/\n?\s*import\s+/i, ''));
};

module.exports.makeMapEntry = function makeMapEntry(filePurs) {
  const dirname = path.dirname(filePurs);

  const basename = path.basename(filePurs, '.purs');

  const fileJs = path.join(dirname, `${basename}.js`);

  const result = Promise.props({
    filePurs: fs.readFileAsync(filePurs, 'utf8'),
    fileJs: fs.readFileAsync(fileJs, 'utf8').catch(() => undefined)
  }).then(fileMap => {
    const sourcePurs = fileMap.filePurs;

    const sourceJs = fileMap.fileJs;

    const moduleName = module.exports.matchModule(sourcePurs);

    const imports = module.exports.matchImports(sourcePurs);

    const map = {};

    map[moduleName] = map[moduleName] || {};

    map[moduleName].src = path.resolve(filePurs);

    map[moduleName].imports = imports;

    if (sourceJs) {
      map[moduleName].ffi = path.resolve(fileJs);
    }

    return map;
  });

  return result;
};

module.exports.makeMap = function makeMap(src) {
  debug('loading PureScript source and FFI files from %o', src);

  const globs = [].concat(src);

  return globby(globs).then(paths =>
    Promise.all(paths.map(module.exports.makeMapEntry)).then(result =>
      result.reduce(Object.assign, {})
    )
  );
};