// Copyright IBM Corp. 2013,2016. All Rights Reserved.
// Node module: loopback-component-explorer
// This file is licensed under the MIT License.
// License text available at https://opensource.org/licenses/MIT

"use strict";

var SG = require("strong-globalize");
SG.SetRootDir(__dirname);
var g = SG();

/*!
 * Adds dynamically-updated docs as /explorer
 */
var deprecated = require("depd")("loopback-explorer");
var url = require("url");
var path = require("path");
var urlJoin = require("./lib/url-join");
var _defaults = require("lodash").defaults;
var cors = require("cors");
var createSwaggerObject = require("loopback-swagger").generateSwaggerSpec;
var SWAGGER_UI_ROOT = require("swagger-ui/index").dist;
var STATIC_ROOT = path.join(__dirname, "public");

module.exports = explorer;
explorer.routes = routes;

/**
 * Example usage:
 *
 * var explorer = require('loopback-component-explorer');
 * explorer(app, options);
 */

function explorer(loopbackApplication, options) {
  options = _defaults({}, options, { mountPath: "/explorer" });
  loopbackApplication.use(
    options.mountPath,
    routes(loopbackApplication, options)
  );
  loopbackApplication.set("loopback-component-explorer", options);
}

function routes(loopbackApplication, options) {
  var loopback = loopbackApplication.loopback;
  var loopbackMajor =
    (loopback && loopback.version && loopback.version.split(".")[0]) || 1;

  if (loopbackMajor < 2) {
    throw new Error(
      g.f(
        "{{loopback-component-explorer}} requires " +
          "{{loopback}} 2.0 or newer"
      )
    );
  }

  options = _defaults({}, options, {
    resourcePath: "swagger.json",
    apiInfo: loopbackApplication.get("apiInfo") || {},
    swaggerUI: true
  });

  var router = new loopback.Router();

  mountSwagger(loopbackApplication, router, options);

  // config.json is loaded by swagger-ui. The server should respond
  // with the relative URI of the resource doc.
  router.get("/config.json", function(req, res) {
    // Get the path we're mounted at. It's best to get this from the referer
    // in case we're proxied at a deep path.
    var source = url.parse(req.headers.referer || "").pathname;
    // If no referer is available, use the incoming url.
    if (!source) {
      source = req.originalUrl.replace(/\/config.json(\?.*)?$/, "");
    }
    res.send({
      url: urlJoin(source, "/" + options.resourcePath)
    });
  });

  if (options.swaggerUI) {
    // Allow specifying a static file roots for swagger files. Any files in
    // these folders will override those in the swagger-ui distribution.
    // In this way one could e.g. make changes to index.html without having
    // to worry about constantly pulling in JS updates.
    if (options.uiDirs) {
      if (typeof options.uiDirs === "string") {
        router.use(loopback.static(options.uiDirs));
      } else if (Array.isArray(options.uiDirs)) {
        options.uiDirs.forEach(function(dir) {
          router.use(loopback.static(dir));
        });
      }
    }

    // File in node_modules are overridden by a few customizations
    router.use(loopback.static(STATIC_ROOT));

    // Swagger UI distribution
    router.use(loopback.static(SWAGGER_UI_ROOT));
  }

  return router;
}

/**
 * Setup Swagger documentation on the given express app.
 *
 * @param {Application} loopbackApplication The loopback application to
 * document.
 * @param {Application} swaggerApp Swagger application used for hosting
 * swagger documentation.
 * @param {Object} opts Options.
 */
function mountSwagger(loopbackApplication, swaggerApp, opts) {
  var swaggerObject = createSwaggerObject(loopbackApplication, opts);

  // listening to modelRemoted event for updating the swaggerObject
  // with the newly created model to appear in the Swagger UI.
  loopbackApplication.on("modelRemoted", function() {
    swaggerObject = createSwaggerObject(loopbackApplication, opts);
  });

  // listening to started event for updating the swaggerObject
  // when a call to app.models.[modelName].nestRemoting([modelName])
  // to appear that method in the Swagger UI.
  loopbackApplication.on("remoteMethodAdded", function() {
    swaggerObject = createSwaggerObject(loopbackApplication, opts);
  });

  // listening to remoteMethodDisabled event for updating the swaggerObject
  // when a remote method is disabled to hide that method in the Swagger UI.
  loopbackApplication.on("remoteMethodDisabled", function() {
    swaggerObject = createSwaggerObject(loopbackApplication, opts);
  });

  var resourcePath = (opts && opts.resourcePath) || "swagger.json";
  if (resourcePath[0] !== "/") resourcePath = "/" + resourcePath;

  var remotes = loopbackApplication.remotes();
  setupCors(swaggerApp, remotes);

  swaggerApp.get(resourcePath, function sendSwaggerObject(req, res) {
    res.status(200).send(swaggerObject);
  });
}

function setupCors(swaggerApp, remotes) {
  var corsOptions = remotes.options && remotes.options.cors;
  if (corsOptions === false) return;

  deprecated(
    g.f(
      "The built-in CORS middleware provided by loopback-component-explorer " +
        "was deprecated. See %s for more details.",
      "https://loopback.io/doc/en/lb3/Security-considerations.html"
    )
  );

  if (corsOptions === undefined) {
    corsOptions = { origin: true, credentials: true };
  }

  swaggerApp.use(cors(corsOptions));
}