/* global Promise */
;(function (exports) {
  'use strict';

  var OAUTH3 = exports.OAUTH3 = {
    utils: {
      clientUri: function (location) {
        return OAUTH3.utils.uri.normalize(location.host + location.pathname);
      }
    , atob: function (base64) {
        return (exports.atob || require('atob'))(base64);
      }
    , _urlSafeBase64ToBase64: function (b64) {
        // URL-safe Base64 to Base64
        // https://en.wikipedia.org/wiki/Base64
        // https://gist.github.com/catwell/3046205
        var mod = b64.length % 4;
        if (2 === mod) { b64 += '=='; }
        if (3 === mod) { b64 += '='; }
        b64 = b64.replace(/-/g, '+').replace(/_/g, '/');
        return b64;
      }
    , uri: {
        normalize: function (uri) {
          // tested with
          //   example.com
          //   example.com/
          //   http://example.com
          //   https://example.com/
          return uri
            .replace(/^(https?:\/\/)?/i, '')
            .replace(/\/?$/, '')
            ;
        }
      }
    , url: {
        normalize: function (url) {
          // tested with
          //   example.com
          //   example.com/
          //   http://example.com
          //   https://example.com/
          return url
            .replace(/^(https?:\/\/)?/i, 'https://')
            .replace(/\/?$/, '')
            ;
        }
      }
    , query: {
        stringify: function (params) {
          var qs = [];

          Object.keys(params).forEach(function (key) {
            // TODO nullify instead?
            if ('undefined' === typeof params[key]) {
              return;
            }

            if ('scope' === key) {
              params[key] = OAUTH3.utils.scope.stringify(params[key]);
            }

            qs.push(encodeURIComponent(key) + '=' + encodeURIComponent(params[key]));
          });

          return qs.join('&');
        }
      }
    , scope: {
        stringify: function (scope) {
          if (Array.isArray(scope)) {
            scope = scope.join(' ');
          }
          return scope;
        }
      }
    , randomState: function () {
        // TODO put in different file for browser vs node
        try {
          return Array.prototype.slice.call(
            window.crypto.getRandomValues(new Uint8Array(16))
          ).map(function (ch) { return (ch).toString(16); }).join('');
        } catch(e) {
          return OAUTH3.utils._insecureRandomState();
        }
      }
    , _insecureRandomState: function () {
        var i;
        var ch;
        var str;
        // TODO use fisher-yates on 0..255 and select [0] 16 times
        // [security] https://medium.com/@betable/tifu-by-using-math-random-f1c308c4fd9d#.5qx0bf95a
        // https://github.com/v8/v8/blob/b0e4dce6091a8777bda80d962df76525dc6c5ea9/src/js/math.js#L135-L144
        // Note: newer versions of v8 do not have this bug, but other engines may still
        console.warn('[security] crypto.getRandomValues() failed, falling back to Math.random()');
        str = '';
        for (i = 0; i < 32; i += 1) {
          ch = Math.round(Math.random() * 255).toString(16);
          if (ch.length < 2) { ch = '0' + ch; }
          str += ch;
        }
        return str;
      }
    }
  , urls: {
      discover: function (providerUri, opts) {
        if (!providerUri) {
          throw new Error("cannot discover without providerUri");
        }
        if (!opts.client_id) {
          throw new Error("cannot discover without options.client_id");
        }
        var clientId = OAUTH3.utils.url.normalize(opts.client_id || opts.client_uri);
        providerUri = OAUTH3.utils.url.normalize(providerUri);

        var params = {
          action: 'directives'
        , state: OAUTH3.utils.randomState()
        , redirect_uri: clientId + (opts.client_callback_path || '/.well-known/oauth3/callback.html#/')
        , response_type: 'rpc'
        , _method: 'GET'
        , _pathname: '.well-known/oauth3/directives.json'
        , debug: opts.debug || undefined
        };

        var result = {
          url: providerUri + '/.well-known/oauth3/#/?' + OAUTH3.utils.query.stringify(params)
        , state: params.state
        , method: 'GET'
        , query: params
        };

        return result;
      }
    }
  , hooks: {
      directives: {
        get: function (providerUri) {
          providerUri = OAUTH3.utils.uri.normalize(providerUri);
          console.warn('[Warn] You should implement: OAUTH3.hooks.directives.get = function (providerUri) { return directives; }');
          if (!OAUTH3.hooks.directives._cache) { OAUTH3.hooks.directives._cache = {}; }
          return JSON.parse(window.localStorage.getItem('directives-' + providerUri) || '{}');
        }
      , set: function (providerUri, directives) {
          providerUri = OAUTH3.utils.uri.normalize(providerUri);
          console.warn('[Warn] You should implement: OAUTH3.hooks.directives.set = function (providerUri, directives) { return directives; }');
          console.warn(directives);
          if (!OAUTH3.hooks.directives._cache) { OAUTH3.hooks.directives._cache = {}; }
          window.localStorage.setItem('directives-' + providerUri, JSON.stringify(directives));
          OAUTH3.hooks.directives._cache[providerUri] = directives;
          return directives;
        }
      }
    }
  , discover: function (providerUri, opts) {
      if (!providerUri) {
        throw new Error('oauth3.discover(providerUri, opts) received providerUri as ' + providerUri);
      }

      return OAUTH3.PromiseA.resolve(OAUTH3.hooks.directives.get(providerUri)).then(function (directives) {
        if (directives && directives.issuer) {
          return directives;
        }
        return OAUTH3._discoverHelper(providerUri, opts).then(function (directives) {
          directives.issuer = directives.issuer || OAUTH3.utils.url.normalize(providerUri);
          // OAUTH3.PromiseA.resolve() is taken care of because this is wrapped
          return OAUTH3.hooks.directives.set(providerUri, directives);
        });
      });
    }
    // this is the browser version
  , _discoverHelper: function (providerUri, opts) {
      return OAUTH3._browser.discover(providerUri, opts);
    }
  , request: function (preq) {
      return OAUTH3._browser.request(preq);
    }
  , implicitGrant: function(providerUri, opts) {
      var promise;

      if (opts.broker) {
        promise = OAUTH3._discoverThenImplicitGrant(providerUri, opts);
      }
      else {
        promise = OAUTH3._implicitGrant(providerUri, opts);
      }

      return promise.then(function (tokens) {
        return OAUTH3.hooks.refreshSession(
          opts.session || {
            provider_uri: providerUri
          , client_id: opts.client_id
          , client_uri: opts.client_uri || opts.clientUri
          }
        , tokens
        );
      });
    }
  , _discoverThenImplicitGrant: function(providerUri, opts) {
      opts.windowType = opts.windowType || 'popup';
      return OAUTH3._discover(providerUri, opts).then(function (directives) {
        return OAUTH3._implicitGrant(directives, opts).then(function (tokens) {
          OAUTH3._browser.closeFrame(tokens.state || opts._state);
          opts._state = undefined;
        });
      });
    }
  , _discover: function(providerUri, opts) {
      providerUri = OAUTH3.utils.url.normalize(providerUri);

      if (providerUri.match(OAUTH3._browser.window.location.hostname)) {
        console.warn("It looks like you're a provider checking for your own directive,"
          + " so we we're just gonna use"
          + " OAUTH3.request({ method: 'GET', url: '.well-known/oauth3/directive.json' })");
        return OAUTH3.request({
          method: 'GET'
        , url: OAUTH3.utils.url.normalize(providerUri) + '/.well-known/oauth3/directives.json'
        });
      }

      if (!(opts.client_id || opts.client_uri).match(OAUTH3._browser.window.location.hostname)) {
        console.warn("It looks like your client_id doesn't match your current window..."
          + " this probably won't end well");
        console.warn(opts.client_id || opts.client_uri, OAUTH3._browser.window.location.hostname);
      }

      var discReq = OAUTH3.urls.discover(
        providerUri
      , { client_id: (opts.client_id || opts.client_uri || OAUTH3.clientUri(OAUTH3._browser.window.location))
        , windowType: opts.broker && opts.windowType || 'background'
        , broker: opts.broker
        , debug: opts.debug
        }
      );
      opts._state = discReq.state;
      //var discReq = OAUTH3.urls.discover(providerUri, opts);

      // hmm... we're gonna need a broker for this since switching windows is distracting,
      // popups are obnoxious, iframes are sometimes blocked, and most servers don't implement CORS
      // eventually it should be the browser (and postMessage may be a viable option now), but whatever...

      // TODO allow postMessage from providerUri in addition to callback
      // TODO allow node to open a desktop browser window
      return OAUTH3._browser.frameRequest(
        discReq.url
      , discReq.state
      , { windowType: opts.windowType
        , reuseWindow: opts.broker && '-broker'
        , debug: opts.debug
        }
      ).then(function (params) {
        // discWin.child.close()
        // TODO params should have response_type indicating json, binary, etc
        var directives = JSON.parse(OAUTH3.utils.atob(OAUTH3.utils.urlSafeBase64ToBase64(params.result || params.directives)));
        return OAUTH3.hooks.directives.set(providerUri, directives);
      });
    }
  , _implicitGrant: function(providerUri, opts) {
      // TODO this may need to be synchronous for browser security policy
      return OAUTH3.PromiseA.resolve(OAUTH3.hooks.directives.get(providerUri)).then(function (directives) {
        // Do some stuff
        var authReq = OAUTH3.urls.implicitGrant(
          directives
        , { redirect_uri: opts.redirect_uri
          , client_id: opts.client_id || opts.client_uri
          , client_uri: opts.client_uri || opts.client_id
          , state: opts._state
          , debug: opts.debug
          }
        );

        if (opts.debug) {
          window.alert("DEBUG MODE: Pausing so you can look at logs and whatnot :) Fire at will!");
        }

        return new OAUTH3.PromiseA(function (resolve, reject) {
          return OAUTH3._browser.frameRequest(
            authReq.url
          , authReq.state // state should recycle params
          , { windowType: opts.windowType
            , reuseWindow: opts.broker && '-broker'
            , debug: opts.debug
            }
          ).then(function (tokens) {
            if (tokens.error) {
              return reject(OAUTH3.utils._formatError(tokens.error));
            }

            OAUTH3._browser.closeFrame(authReq.state, { debug: opts.debug || tokens.debug });

            return tokens;
          });
        });
      });
    }


    //
    // Let the Code Waste begin!!
    //
  , _browser: {
      window: window
      // TODO we don't need to include this if we're using jQuery or angular
    , request: function (preq, _sys) {
        return new OAUTH3.PromiseA(function (resolve, reject) {
          var xhr;
          try {
            xhr = new XMLHttpRequest(_sys);
          } catch(e) {
            xhr = new XMLHttpRequest();
          }
          xhr.onreadystatechange = function () {
            console.error('state change');
            var data;
            if (xhr.readyState !== XMLHttpRequest.DONE) {
              // nothing to do here
              return;
            }

            if (xhr.status !== 200) {
              reject(new Error('bad status code: ' + xhr.status));
              return;
            }

            try {
              data = JSON.parse(xhr.responseText);
            } catch(e) {
              data = xhr.responseText;
            }

            resolve({
              request: xhr
            , data: data
            , status: xhr.status
            });
          };
          xhr.open(preq.method, preq.url, true);
          var headers = preq.headers || {};
          Object.keys(headers).forEach(function (key) {
            xhr.setRequestHeader(key, headers[key]);
          });
          xhr.send();
        });
      }
    , discover: function (providerUri, opts) {
        opts = opts || {};
        //opts.debug = true;
        providerUri = OAUTH3.utils.url.normalize(providerUri);
        if (providerUri.match(OAUTH3._browser.window.location.hostname)) {
          console.warn("It looks like you're a provider checking for your own directive,"
            + " so we we're just gonna use OAUTH3.request({ method: 'GET', url: '.well-known/oauth3/directive.json' })");
          return OAUTH3.request({
            method: 'GET'
          , url: OAUTH3.utils.url.normalize(providerUri) + '/.well-known/oauth3/directives.json'
          });
        }

        if (!(opts.client_id || opts.client_uri).match(OAUTH3._browser.window.location.hostname)) {
          console.warn("It looks like your client_id doesn't match your current window... this probably won't end well");
          console.warn(opts.client_id || opts.client_uri, OAUTH3._browser.window.location.hostname);
        }
        var discObj = OAUTH3.urls.discover(
          providerUri
        , { client_id: (opts.client_id || opts.client_uri || OAUTH3.clientUri(OAUTH3._browser.window.location)), debug: opts.debug }
        );

        // TODO ability to reuse iframe instead of closing
        return OAUTH3._browser._iframe.insert(discObj.url, discObj.state, opts).then(function (params) {
          OAUTH3._browser.closeFrame(discObj.state, { debug: opts.debug || params.debug });
          if (params.error) {
            return OAUTH3.utils._formatError(providerUri, params.error);
          }
          var directives = JSON.parse(OAUTH3.utils.atob(OAUTH3.utils._urlSafeBase64ToBase64(params.result || params.directives)));
          return directives;
        }, function (err) {
          OAUTH3._browser.closeFrame(discObj.state, { debug: opts.debug || err.debug });
          return OAUTH3.PromiseA.reject(err);
        });
      }
    , frameRequest: function (url, state, opts) {
        var previousFrame = OAUTH3._browser._frames[state];

        if (!opts.windowType) {
          opts.windowType = 'popup';
        }

        opts = opts || {};
        if (opts.debug) {
          opts.timeout = opts.timeout || 15 * 60 * 1000;
        }

        return new OAUTH3.PromiseA(function (resolve, reject) {
          var tok;

          function cleanup() {
            delete window['--oauth3-callback-' + state];
            clearTimeout(tok);
            tok = null;
          }

          window['--oauth3-callback-' + state] = function (params) {
            resolve(params);
            cleanup();
          };

          tok = setTimeout(function () {
            var err = new Error("the iframe request did not complete within 15 seconds");
            err.code = "E_TIMEOUT";
            reject(err);
            cleanup();
          }, opts.timeout || 15 * 1000);

          if ('background' === opts.windowType) {
            if (previousFrame) {
              previousFrame.location = url;
              //promise = previousFrame.promise;
            }
            else {
              OAUTH3._browser._iframe.insert(url, state, opts);
            }
          } else if ('popup' === opts.windowType) {
            if (previousFrame) {
              previousFrame.location = url;
              if (opts.debug) {
                previousFrame.focus();
              }
            }
            else {
              OAUTH3._browser.frame.open(url, state, opts);
            }
          } else if ('inline' === opts.windowType) {
            // callback function will never execute and would need to redirect back to current page
            // rather than the callback.html
            url += '&original_url=' + OAUTH3._browser.window.location.href;
            OAUTH3._browser.window.location = url;
            //promise = OAUTH3.PromiseA.resolve({ url: url });
            return;
          } else {
            throw new Error("login framing method options.windowType="
              + opts.windowType + " not type yet implemented");
          }

        }).then(function (params) {
          var err;

          if (params.error || params.error_description) {
            err = new Error(params.error_description || "Unknown response error");
            err.code = params.error || "E_UKNOWN_ERROR";
            err.params = params;
            //_formatError
            return OAUTH3.PromiseA.reject(err);
          }

          return params;
        });
      }
    , closeFrame: function (state, opts) {
        function close() {
          try {
            OAUTH3._browser._frames[state].close();
          } catch(e) {
            try {
              OAUTH3._browser._frames[state].remove();
            } catch(e) {
            }
          }

          delete OAUTH3._browser._frames[state];
        }

        if (opts.debug) {
          if (window.confirm("DEBUG MODE: okay to close oauth3 window?")) {
            close();
          }
        }
        else {
          close();
        }
      }
    , _frames: {}
    , iframe: {
        insert: function (url, state, opts) {
          // TODO hidden / non-hidden (via directive even)
          var framesrc = '<iframe class="js-oauth3-iframe" src="' + url + '" ';
          if (opts.debug) {
            framesrc += ' width="800px" height="800px" style="opacity: 0.8;" frameborder="1"';
          }
          else {
            framesrc += ' width="1px" height="1px" frameborder="0"';
          }
          framesrc += '></iframe>';

          var frame = OAUTH3._browser._frames[state] = OAUTH3._browser.window.document.createElement('div');
          OAUTH3._browser._frames[state].innerHTML = framesrc;
          OAUTH3._browser.window.document.body.appendChild(OAUTH3._browser._frames[state]);

          return frame;
        }
      }
    , frame: {
        open: function (url, state, opts) {
          if (opts.debug) {
            opts.timeout = opts.timeout || 15 * 60 * 1000;
          }

          var promise = new OAUTH3.PromiseA(function (resolve, reject) {
            var tok;

            function cleanup() {
              clearTimeout(tok);
              tok = null;
              delete window['--oauth3-callback-' + state];
              // close is done later in case the window is reused or self-closes synchronously itself / by parent
              // (probably won't ever happen, but that's a negotiable implementation detail)
            }

            window['--oauth3-callback-' + state] = function (params) {
              console.log('YOLO!!');
              resolve(params);
              cleanup();
            };

            tok = setTimeout(function () {
              var err = new Error("the windowed request did not complete within 3 minutes");
              err.code = "E_TIMEOUT";
              reject(err);
              cleanup();
            }, opts.timeout || 3 * 60 * 1000);

            setTimeout(function () {
              if (!promise.child) {
                reject("TODO: open the iframe first and discover oauth3 directives before popup");
                cleanup();
              }
            }, 0);
          });

          // TODO allow size changes (via directive even)
          OAUTH3._browser._frames[state] = window.open(
            url
          , 'oauth3-login-' + (opts.reuseWindow || state)
          , 'height=' + (opts.height || 720) + ',width=' + (opts.width || 620)
          );
          // TODO periodically garbage collect expired handlers from window object
          return promise;
        }
      }
    }
  };
  if ('undefined' !== typeof Promise) {
    OAUTH3.PromiseA = Promise;
  }

}('undefined' !== typeof exports ? exports : window));