var RequestShortener = require("webpack/lib/RequestShortener");
var _ = require("lodash");

/**
 * TODO Docs
 * @example new NamedModulesPlugin(/^\.\/app\/(viewmodels|records|adapters)/, /^\.\/app\/(.*)\.js$/)
 */
function NamedModulesPlugin(fileWhitelistRegex, replacementRegex) {
  this.fileWhitelistRegex = fileWhitelistRegex;
  this.replacementRegex = replacementRegex;
}
module.exports = NamedModulesPlugin;

NamedModulesPlugin.prototype.apply = function(compiler) {
  if (!this.fileWhitelistRegex) throw new Error();
  if (!this.replacementRegex) throw new Error();
  var fileWhitelistRegex = this.fileWhitelistRegex;
  var replacementRegex = this.replacementRegex;
  var compilerContext = compiler.context;

  compiler.plugin("this-compilation", function(compilation) {
    var mainTemplate = compilation.mainTemplate;

    mainTemplate.plugin("local-vars", function(source, chunk/*, hash*/) {
      var self = this;
      var buf = [];
      buf.push(this.asString([
        source,
        "// The module cache",
        "var installedModules = {};"
      ]));
      buf.push("// Module request paths (NamedModulesPlugin)");
      buf.push(this.requireFn + ".moduleNames = {");
      chunk.modules.forEach(function(m){
        var requestShortener = new RequestShortener(compilerContext);
        var shortened = requestShortener.shorten(m.userRequest);
        var isWhitelisted = shortened && shortened.match(fileWhitelistRegex);
        if (isWhitelisted){
          var name = shortened && shortened.replace(replacementRegex, '$1');
          buf.push(self.indent(m.id + ": '" + name + "',"));
        }
      });
      buf.push("};");
      return this.asString(buf);
    });

    // TODO Refactor
    // See monkey-patch below
    var requirePlugin = function(source, chunk, hash) {
      return this.asString([
        source,
        "// Check if module is in cache",
        "if(installedModules[moduleId])",
        this.indent("return installedModules[moduleId].exports;"),
        "",
        "// Create a new module (and put it into the cache)",
        "var module = installedModules[moduleId] = {",
        this.indent(this.applyPluginsWaterfall("module-obj", "", chunk, hash, "moduleId")),
        "};",
        "",
        "// Execute the module function",
        "modules[moduleId].call(module.exports, module, module.exports, " + this.renderRequireFunctionForModule(hash, chunk, "moduleId") + ");",
        "",
        "// Flag the module as loaded",
        "module.loaded = true;",
        "",
        "// (NamedModulesPlugin) Set __moduleName__ on prototype of exported module",
        "var moduleName = " + this.requireFn + ".moduleNames[moduleId];",
        "if (moduleName && typeof module.exports === 'function'){",
        this.indent("module.exports.prototype.__moduleId__ = moduleName;"),
        "}",

        "// Return the exports of the module",
        "return module.exports;"
      ]);
    };
    requirePlugin.__namedModulesPlugin = true;
    mainTemplate.plugin("require", requirePlugin);
  });
};

// TODO Temporary
// Monkey-patch MainTemplate.prototype.applyPluginsWaterfall to throw away the original tapable "render" plugin (defined in MainTemplate constructor). We only want to use the "render" plugin defined above.
var MainTemplate = require("webpack/lib/MainTemplate");
var orig = MainTemplate.prototype.applyPluginsWaterfall;
MainTemplate.prototype.applyPluginsWaterfall = function(){
  if (this._plugins["require"].length > 1){
    this._plugins["require"] = _.filter(this._plugins["require"], '__namedModulesPlugin');
  }
  return orig.apply(this, arguments);
};