var Q = require("q");
  var Cookie = require("../http-cookie");
  
  exports.CookieJar = function (app) {
      var hostCookies = {}; // to {} of pathCookies to [] of cookies
      return function (request) {
  
          var hosts = allHostsContaining(request.headers.host);
  
          var now = new Date();
  
          var requestCookies = concat(hosts.map(function (host) {
  
              // delete expired cookies
              for (var host in hostCookies) {
                  var pathCookies = hostCookies[host];
                  for (var path in pathCookies) {
                      var cookies = pathCookies[path];
                      for (var name in cookies) {
                          var cookie = cookies[name];
                          if (cookie.expires && cookie.expires > now) {
                              delete cookie[name];
                          }
                      }
                  }
              }
  
              // collect applicable cookies
              return concat(
                  Object.keys(hostCookies)
                  .map(function (host) {
                      if (!hostContains(host, request.headers.host))
                          return [];
                      var pathCookies = hostCookies[host];
                      return concat(
                          Object.keys(pathCookies)
                          .map(function (path) {
                              if (!pathContains(path, request.path))
                                  return [];
                              var cookies = pathCookies[path];
                              return (
                                  Object.keys(cookies)
                                  .map(function (name) {
                                      return cookies[name];
                                  })
                                  .filter(function (cookie) {
                                      return cookie.secure ?
                                          request.ssl :
                                          true;
                                  })
                              );
                          })
                      )
                  })
              );
  
          }));
  
          if (requestCookies.length) {
              request.headers["cookie"] = (
                  requestCookies
                  .map(function (cookie) {
                      return Cookie.stringify(
                          cookie.key,
                          cookie.value,
                          cookie
                      );
                  })
                  .join("; ")
              );
          }
  
          return Q.when(app.apply(this, arguments), function (response) {
              response.headers = response.headers || {};
              if (response.headers["set-cookie"]) {
                  var requestHost = ipRe.test(request.headers.host) ?
                      request.headers.host :
                      "." + request.headers.host;
                  // normalize to array
                  if (!Array.isArray(response.headers["set-cookie"])) {
                      response.headers["set-cookie"] = [response.headers["set-cookie"]];
                  }
                  response.headers["set-cookie"].forEach(function (cookie) {
                      var date = response.headers["date"] ?
                          new Date(response.headers["date"]) :
                          new Date();
                      cookie = Cookie.parse(cookie, date);
                      // ignore illegal host
                      if (cookie.host && !hostContains(requestHost, cookie.host))
                          delete cookie.host;
                      var host = requestHost || cookie.host;
                      var path = cookie.path || "/";
                      var pathCookies = hostCookies[host] = hostCookies[host] || {};
                      var cookies = pathCookies[path] = pathCookies[path] || {};
                      cookies[cookie.key] = cookie;
                  })
                  delete response.headers["set-cookie"];
              }
  
              return response;
          });
  
      };
  };
  
  var ipRe = /^\d+\.\d+\.\d+\.\d+$/;
  
  function allHostsContaining(content) {
      if (ipRe.test(content)) {
          return [content];
      } if (content === "localhost") {
          return [content];
      } else {
          var parts = content.split(".");
          var hosts = [];
          while (parts.length > 1) {
              hosts.push("." + parts.join("."));
              parts.shift();
          }
          return hosts;
      }
  }
  
  function hostContains(container, content) {
      if (ipRe.test(container) || ipRe.test(content)) {
          return container === content;
      } else if (/^\./.test(container)) {
          return (
              content.lastIndexOf(container) ===
              content.length - container.length
          ) || (
              container.slice(1) === content
          );
      } else {
          return container === content;
      }
  };
  
  function pathContains(container, content) {
      if (/^\/$/.test(container)) {
          return content.indexOf(container) === 0;
      } else {
          return (
              content === container ||
              content.indexOf(container + "/") === 0
          );
      }
  }
  
  function concat(arrays) {
      return [].concat.apply([], arrays);
  }