'use strict';

/*!
 * Pug
 * Copyright(c) 2010 TJ Holowaychuk <tj@vision-media.ca>
 * MIT Licensed
 */

/**
 * Module dependencies.
 */

var fs = require('fs');
var path = require('path');
var lex = require('pug-lexer');
var stripComments = require('pug-strip-comments');
var parse = require('pug-parser');
var load = require('pug-load');
var filters = require('pug-filters');
var link = require('pug-linker');
var generateCode = require('pug-code-gen');
var runtime = require('pug-runtime');
var runtimeWrap = require('pug-runtime/wrap');

/**
 * Pug runtime helpers.
 */

exports.runtime = runtime;

/**
 * Template function cache.
 */

exports.cache = {};

function applyPlugins(value, options, plugins, name) {
  return plugins.reduce(function (value, plugin) {
    return (
      plugin[name]
      ? plugin[name](value, options)
      : value
    );
  }, value);
}

function findReplacementFunc(plugins, name) {
  var eligiblePlugins = plugins.filter(function (plugin) {
    return plugin[name];
  });

  if (eligiblePlugins.length > 1) {
    throw new Error('Two or more plugins all implement ' + name + ' method.');
  } else if (eligiblePlugins.length) {
    return eligiblePlugins[0][name];
  }
  return null;
}

/**
 * Object for global custom filters.  Note that you can also just pass a `filters`
 * option to any other method.
 */
exports.filters = {};

/**
 * Compile the given `str` of pug and return a function body.
 *
 * @param {String} str
 * @param {Object} options
 * @return {Object}
 * @api private
 */

function compileBody(str, options){
  var debug_sources = {};
  debug_sources[options.filename] = str;
  var dependencies = [];
  var plugins = options.plugins || [];
  var ast = load.string(str, {
    filename: options.filename,
    basedir: options.basedir,
    lex: function (str, options) {
      var lexOptions = {};
      Object.keys(options).forEach(function (key) {
        lexOptions[key] = options[key];
      });
      lexOptions.plugins = plugins.filter(function (plugin) {
        return !!plugin.lex;
      }).map(function (plugin) {
        return plugin.lex;
      });
      return applyPlugins(lex(str, lexOptions), options, plugins, 'postLex');
    },
    parse: function (tokens, options) {
      tokens = tokens.map(function (token) {
        if (token.type === 'path' && path.extname(token.val) === '') {
          return {
            type: 'path',
            line: token.line,
            col: token.col,
            val: token.val + '.pug'
          };
        }
        return token;
      });
      tokens = stripComments(tokens, options);
      tokens = applyPlugins(tokens, options, plugins, 'preParse');
      var parseOptions = {};
      Object.keys(options).forEach(function (key) {
        parseOptions[key] = options[key];
      });
      parseOptions.plugins = plugins.filter(function (plugin) {
        return !!plugin.parse;
      }).map(function (plugin) {
        return plugin.parse;
      });

      return applyPlugins(
        applyPlugins(parse(tokens, parseOptions), options, plugins, 'postParse'),
        options, plugins, 'preLoad'
      );
    },
    resolve: function (filename, source, loadOptions) {
      var replacementFunc = findReplacementFunc(plugins, 'resolve');
      if (replacementFunc) {
        return replacementFunc(filename, source, options);
      }

      return load.resolve(filename, source, loadOptions);
    },
    read: function (filename, loadOptions) {
      dependencies.push(filename);

      var contents;

      var replacementFunc = findReplacementFunc(plugins, 'read');
      if (replacementFunc) {
        contents = replacementFunc(filename, options);
      } else {
        contents = load.read(filename, loadOptions);
      }

      var str = applyPlugins(contents, {filename: filename}, plugins, 'preLex');
      debug_sources[filename] = str;
      return str;
    }
  });
  ast = applyPlugins(ast, options, plugins, 'postLoad');
  ast = applyPlugins(ast, options, plugins, 'preFilters');

  var filtersSet = {};
  Object.keys(exports.filters).forEach(function (key) {
    filtersSet[key] = exports.filters[key];
  });
  if (options.filters) {
    Object.keys(options.filters).forEach(function (key) {
      filtersSet[key] = options.filters[key];
    });
  }
  ast = filters.handleFilters(ast, filtersSet, options.filterOptions);

  ast = applyPlugins(ast, options, plugins, 'postFilters');
  ast = applyPlugins(ast, options, plugins, 'preLink');
  ast = link(ast);
  ast = applyPlugins(ast, options, plugins, 'postLink');

  // Compile
  ast = applyPlugins(ast, options, plugins, 'preCodeGen');
  var js = generateCode(ast, {
    pretty: options.pretty,
    compileDebug: options.compileDebug,
    doctype: options.doctype,
    inlineRuntimeFunctions: options.inlineRuntimeFunctions,
    globals: options.globals,
    self: options.self,
    includeSources: options.includeSources ? debug_sources : false,
    templateName: options.templateName
  });
  js = applyPlugins(js, options, plugins, 'postCodeGen');

  // Debug compiler
  if (options.debug) {
    console.error('\nCompiled Function:\n\n\u001b[90m%s\u001b[0m', js.replace(/^/gm, '  '));
  }

  return {body: js, dependencies: dependencies};
}

/**
 * Get the template from a string or a file, either compiled on-the-fly or
 * read from cache (if enabled), and cache the template if needed.
 *
 * If `str` is not set, the file specified in `options.filename` will be read.
 *
 * If `options.cache` is true, this function reads the file from
 * `options.filename` so it must be set prior to calling this function.
 *
 * @param {Object} options
 * @param {String=} str
 * @return {Function}
 * @api private
 */
function handleTemplateCache (options, str) {
  var key = options.filename;
  if (options.cache && exports.cache[key]) {
    return exports.cache[key];
  } else {
    if (str === undefined) str = fs.readFileSync(options.filename, 'utf8');
    var templ = exports.compile(str, options);
    if (options.cache) exports.cache[key] = templ;
    return templ;
  }
}

/**
 * Compile a `Function` representation of the given pug `str`.
 *
 * Options:
 *
 *   - `compileDebug` when `false` debugging code is stripped from the compiled
       template, when it is explicitly `true`, the source code is included in
       the compiled template for better accuracy.
 *   - `filename` used to improve errors when `compileDebug` is not `false` and to resolve imports/extends
 *
 * @param {String} str
 * @param {Options} options
 * @return {Function}
 * @api public
 */

exports.compile = function(str, options){
  var options = options || {}

  str = String(str);

  var parsed = compileBody(str, {
    compileDebug: options.compileDebug !== false,
    filename: options.filename,
    basedir: options.basedir,
    pretty: options.pretty,
    doctype: options.doctype,
    inlineRuntimeFunctions: options.inlineRuntimeFunctions,
    globals: options.globals,
    self: options.self,
    includeSources: options.compileDebug === true,
    debug: options.debug,
    templateName: 'template',
    filters: options.filters,
    filterOptions: options.filterOptions,
    plugins: options.plugins,
  });

  var res = options.inlineRuntimeFunctions
    ? new Function('', parsed.body + ';return template;')()
    : runtimeWrap(parsed.body);

  res.dependencies = parsed.dependencies;

  return res;
};

/**
 * Compile a JavaScript source representation of the given pug `str`.
 *
 * Options:
 *
 *   - `compileDebug` When it is `true`, the source code is included in
 *     the compiled template for better error messages.
 *   - `filename` used to improve errors when `compileDebug` is not `true` and to resolve imports/extends
 *   - `name` the name of the resulting function (defaults to "template")
 *
 * @param {String} str
 * @param {Options} options
 * @return {Object}
 * @api public
 */

exports.compileClientWithDependenciesTracked = function(str, options){
  var options = options || {};

  str = String(str);
  var parsed = compileBody(str, {
    compileDebug: options.compileDebug,
    filename: options.filename,
    basedir: options.basedir,
    pretty: options.pretty,
    doctype: options.doctype,
    inlineRuntimeFunctions: options.inlineRuntimeFunctions !== false,
    globals: options.globals,
    self: options.self,
    includeSources: options.compileDebug,
    debug: options.debug,
    templateName: options.name || 'template',
    filters: options.filters,
    filterOptions: options.filterOptions,
    plugins: options.plugins,
  });

  return {body: parsed.body, dependencies: parsed.dependencies};
};

/**
 * Compile a JavaScript source representation of the given pug `str`.
 *
 * Options:
 *
 *   - `compileDebug` When it is `true`, the source code is included in
 *     the compiled template for better error messages.
 *   - `filename` used to improve errors when `compileDebug` is not `true` and to resolve imports/extends
 *   - `name` the name of the resulting function (defaults to "template")
 *
 * @param {String} str
 * @param {Options} options
 * @return {String}
 * @api public
 */
exports.compileClient = function (str, options) {
  return exports.compileClientWithDependenciesTracked(str, options).body;
};

/**
 * Compile a `Function` representation of the given pug file.
 *
 * Options:
 *
 *   - `compileDebug` when `false` debugging code is stripped from the compiled
       template, when it is explicitly `true`, the source code is included in
       the compiled template for better accuracy.
 *
 * @param {String} path
 * @param {Options} options
 * @return {Function}
 * @api public
 */
exports.compileFile = function (path, options) {
  options = options || {};
  options.filename = path;
  return handleTemplateCache(options);
};

/**
 * Render the given `str` of pug.
 *
 * Options:
 *
 *   - `cache` enable template caching
 *   - `filename` filename required for `include` / `extends` and caching
 *
 * @param {String} str
 * @param {Object|Function} options or fn
 * @param {Function|undefined} fn
 * @returns {String}
 * @api public
 */

exports.render = function(str, options, fn){
  // support callback API
  if ('function' == typeof options) {
    fn = options, options = undefined;
  }
  if (typeof fn === 'function') {
    var res
    try {
      res = exports.render(str, options);
    } catch (ex) {
      return fn(ex);
    }
    return fn(null, res);
  }

  options = options || {};

  // cache requires .filename
  if (options.cache && !options.filename) {
    throw new Error('the "filename" option is required for caching');
  }

  return handleTemplateCache(options, str)(options);
};

/**
 * Render a Pug file at the given `path`.
 *
 * @param {String} path
 * @param {Object|Function} options or callback
 * @param {Function|undefined} fn
 * @returns {String}
 * @api public
 */

exports.renderFile = function(path, options, fn){
  // support callback API
  if ('function' == typeof options) {
    fn = options, options = undefined;
  }
  if (typeof fn === 'function') {
    var res
    try {
      res = exports.renderFile(path, options);
    } catch (ex) {
      return fn(ex);
    }
    return fn(null, res);
  }

  options = options || {};

  options.filename = path;
  return handleTemplateCache(options)(options);
};


/**
 * Compile a Pug file at the given `path` for use on the client.
 *
 * @param {String} path
 * @param {Object} options
 * @returns {String}
 * @api public
 */

exports.compileFileClient = function(path, options){
  var key = path + ':client';
  options = options || {};

  options.filename = path;

  if (options.cache && exports.cache[key]) {
    return exports.cache[key];
  }

  var str = fs.readFileSync(options.filename, 'utf8');
  var out = exports.compileClient(str, options);
  if (options.cache) exports.cache[key] = out;
  return out;
};

/**
 * Express support.
 */

exports.__express = function(path, options, fn) {
  if(options.compileDebug == undefined && process.env.NODE_ENV === 'production') {
    options.compileDebug = false;
  }
  exports.renderFile(path, options, fn);
}
