const glob = require('glob');
const {getOptions} = require('loader-utils');
const path = require('path');
const validateOptions = require('schema-utils');

const schema = {
  type: 'object',
  properties: {
    paths: {
      items: {
        type: 'string',
      },
      type: 'array',
    },
    registrar: {
      type: 'object',
      properties: {
        function: {
          type: 'string',
        },
        module: {
          type: 'string',
        },
      },
      required: [
        'function',
        'module',
      ],
    },
    type: {
      type: 'string',
    },
  },
  required: [
    'registrar',
    'type',
  ],
};

// Dynamically require all traits.
module.exports = function(source) {
  const options = getOptions(this);
  // Validate schema.
  validateOptions(schema, options, 'Avocado defgen');
  // Extract options.
  const {paths, registrar, type} = options;
  // Search avocado.
  options.paths.push(path.resolve(
    __dirname, 'node_modules', '@avocado',
  ));
  // Get all trait source paths.
  const sourcePaths = [];
  paths.forEach((path) => {
    const files = glob.sync(`${path}/**/*.${type}.js`, {
      follow: true,
    });
    sourcePaths.push(...files);
  });
  // Build import definitions.
  const importDefinitions = sourcePaths.map((sourcePath) => {
    const relativePath = path.relative(__dirname, sourcePath);
    const basename = path.basename(relativePath, `.${type}.js`);
    const parts = relativePath.split('/');
    // Chop off basename.
    parts.pop();
    // Module or local?
    let importDirectory;
    if ('node_modules' === parts[0]) {
      importDirectory = `${parts.slice(1).join('/')}`;
    }
    else {
      importDirectory = `./${parts.join('/')}`
    }
    const importPath = `${importDirectory}/${basename}.${type}`;
    // Extract class name.
    const baseparts = basename.split('-');
    const className = baseparts.reduce((className, part) => {
      const firstLetter = part.charAt(0).toUpperCase();
      const rest = part.substr(1).toLowerCase();
      return className + firstLetter + rest;
    }, '');
    // Import and register.
    return [
      `import {${className}} from '${importPath}';`,
      `${registrar.function}(${className});`,
    ].join('\n');
  });
  // Import trait registry first.
  return [
    `import {${registrar.function}} from '${registrar.module}'`,
    '',
    ...importDefinitions
  ].join('\n');
}