/*!
 * Module Dependencies.
 */

var loopback = require('../../lib/loopback');
var utils = require('../../lib/utils');
var path = require('path');
var SALT_WORK_FACTOR = 10;
var crypto = require('crypto');

var bcrypt;
try {
  // Try the native module first
  bcrypt = require('bcrypt');
  // Browserify returns an empty object
  if (bcrypt && typeof bcrypt.compare !== 'function') {
    bcrypt = require('bcryptjs');
  }
} catch (err) {
  // Fall back to pure JS impl
  bcrypt = require('bcryptjs');
}

var DEFAULT_TTL = 1209600; // 2 weeks in seconds
var DEFAULT_RESET_PW_TTL = 15 * 60; // 15 mins in seconds
var DEFAULT_MAX_TTL = 31556926; // 1 year in seconds
var assert = require('assert');

var debug = require('debug')('loopback:user');

/**
 * Built-in User model.
 * Extends LoopBack [PersistedModel](#persistedmodel-new-persistedmodel).
 *
 * Default `User` ACLs.
 *
 * - DENY EVERYONE `*`
 * - ALLOW EVERYONE `create`
 * - ALLOW OWNER `deleteById`
 * - ALLOW EVERYONE `login`
 * - ALLOW EVERYONE `logout`
 * - ALLOW EVERYONE `findById`
 * - ALLOW OWNER `updateAttributes`
 *
 * @property {String} username Must be unique
 * @property {String} password Hidden from remote clients
 * @property {String} email Must be valid email
 * @property {Boolean} emailVerified Set when a user's email has been verified via `confirm()`
 * @property {String} verificationToken Set when `verify()` is called
 * @property {Object} settings Extends the `Model.settings` object.
 * @property {Boolean} settings.emailVerificationRequired Require the email verification
 * process before allowing a login.
 * @property {Number} settings.ttl Default time to live (in seconds) for the `AccessToken` created by `User.login() / user.createAccessToken()`.
 * Default is `1209600` (2 weeks)
 * @property {Number} settings.maxTTL The max value a user can request a token to be alive / valid for.
 * Default is `31556926` (1 year)
 * @property {Boolean} settings.realmRequired Require a realm when logging in a user.
 * @property {String} settings.realmDelimiter When set a realm is required.
 * @property {Number} settings.resetPasswordTokenTTL Time to live for password reset `AccessToken`. Default is `900` (15 minutes).
 * @property {Number} settings.saltWorkFactor The `bcrypt` salt work factor. Default is `10`.
 *
 * @class User
 * @inherits {PersistedModel}
 */

module.exports = function(User) {

  /**
   * Create access token for the logged in user. This method can be overridden to
   * customize how access tokens are generated
   *
   * @param {Number} ttl The requested ttl
   * @param {Object} [options] The options for access token, such as scope, appId
   * @callback {Function} cb The callback function
   * @param {String|Error} err The error string or object
   * @param {AccessToken} token The generated access token object
   */
  User.prototype.createAccessToken = function(ttl, options, cb) {
    if (cb === undefined && typeof options === 'function') {
      // createAccessToken(ttl, cb)
      cb = options;
      options = undefined;
    }

    cb = cb || utils.createPromiseCallback();

    if (typeof ttl === 'object' && !options) {
      // createAccessToken(options, cb)
      options = ttl;
      ttl = options.ttl;
    }
    options = options || {};
    var userModel = this.constructor;
    ttl = Math.min(ttl || userModel.settings.ttl, userModel.settings.maxTTL);
    this.accessTokens.create({
      ttl: ttl
    }, cb);
    return cb.promise;
  };

  function splitPrincipal(name, realmDelimiter) {
    var parts = [null, name];
    if (!realmDelimiter) {
      return parts;
    }
    var index = name.indexOf(realmDelimiter);
    if (index !== -1) {
      parts[0] = name.substring(0, index);
      parts[1] = name.substring(index + realmDelimiter.length);
    }
    return parts;
  }

  /**
   * Normalize the credentials
   * @param {Object} credentials The credential object
   * @param {Boolean} realmRequired
   * @param {String} realmDelimiter The realm delimiter, if not set, no realm is needed
   * @returns {Object} The normalized credential object
   */
  User.normalizeCredentials = function(credentials, realmRequired, realmDelimiter) {
    var query = {};
    credentials = credentials || {};
    if (!realmRequired) {
      if (credentials.email) {
        query.email = credentials.email;
      } else if (credentials.username) {
        query.username = credentials.username;
      }
    } else {
      if (credentials.realm) {
        query.realm = credentials.realm;
      }
      var parts;
      if (credentials.email) {
        parts = splitPrincipal(credentials.email, realmDelimiter);
        query.email = parts[1];
        if (parts[0]) {
          query.realm = parts[0];
        }
      } else if (credentials.username) {
        parts = splitPrincipal(credentials.username, realmDelimiter);
        query.username = parts[1];
        if (parts[0]) {
          query.realm = parts[0];
        }
      }
    }
    return query;
  };

  /**
   * Login a user by with the given `credentials`.
   *
   * ```js
   *    User.login({username: 'foo', password: 'bar'}, function (err, token) {
  *      console.log(token.id);
  *    });
   * ```
   *
   * @param {Object} credentials username/password or email/password
   * @param {String[]|String} [include] Optionally set it to "user" to include
   * the user info
   * @callback {Function} callback Callback function
   * @param {Error} err Error object
   * @param {AccessToken} token Access token if login is successful
   */

  User.login = function(credentials, include, fn) {
    var self = this;
    if (typeof include === 'function') {
      fn = include;
      include = undefined;
    }

    fn = fn || utils.createPromiseCallback();

    include = (include || '');
    if (Array.isArray(include)) {
      include = include.map(function(val) {
        return val.toLowerCase();
      });
    } else {
      include = include.toLowerCase();
    }

    var realmDelimiter;
    // Check if realm is required
    var realmRequired = !!(self.settings.realmRequired ||
      self.settings.realmDelimiter);
    if (realmRequired) {
      realmDelimiter = self.settings.realmDelimiter;
    }
    var query = self.normalizeCredentials(credentials, realmRequired,
      realmDelimiter);

    if (realmRequired && !query.realm) {
      var err1 = new Error('realm is required');
      err1.statusCode = 400;
      err1.code = 'REALM_REQUIRED';
      fn(err1);
      return fn.promise;
    }
    if (!query.email && !query.username) {
      var err2 = new Error('username or email is required');
      err2.statusCode = 400;
      err2.code = 'USERNAME_EMAIL_REQUIRED';
      fn(err2);
      return fn.promise;
    }

    self.findOne({where: query}, function(err, user) {
      var defaultError = new Error('login failed');
      defaultError.statusCode = 401;
      defaultError.code = 'LOGIN_FAILED';

      function tokenHandler(err, token) {
        if (err) return fn(err);
        if (Array.isArray(include) ? include.indexOf('user') !== -1 : include === 'user') {
          // NOTE(bajtos) We can't set token.user here:
          //  1. token.user already exists, it's a function injected by
          //     "AccessToken belongsTo User" relation
          //  2. ModelBaseClass.toJSON() ignores own properties, thus
          //     the value won't be included in the HTTP response
          // See also loopback#161 and loopback#162
          token.__data.user = user;
        }
        fn(err, token);
      }

      if (err) {
        debug('An error is reported from User.findOne: %j', err);
        fn(defaultError);
      } else if (user) {
        user.hasPassword(credentials.password, function(err, isMatch) {
          if (err) {
            debug('An error is reported from User.hasPassword: %j', err);
            fn(defaultError);
          } else if (isMatch) {
            if (self.settings.emailVerificationRequired && !user.emailVerified) {
              // Fail to log in if email verification is not done yet
              debug('User email has not been verified');
              err = new Error('login failed as the email has not been verified');
              err.statusCode = 401;
              err.code = 'LOGIN_FAILED_EMAIL_NOT_VERIFIED';
              fn(err);
            } else {
              if (user.createAccessToken.length === 2) {
                user.createAccessToken(credentials.ttl, tokenHandler);
              } else {
                user.createAccessToken(credentials.ttl, credentials, tokenHandler);
              }
            }
          } else {
            debug('The password is invalid for user %s', query.email || query.username);
            fn(defaultError);
          }
        });
      } else {
        debug('No matching record is found for user %s', query.email || query.username);
        fn(defaultError);
      }
    });
    return fn.promise;
  };

  /**
   * Logout a user with the given accessToken id.
   *
   * ```js
   *    User.logout('asd0a9f8dsj9s0s3223mk', function (err) {
  *      console.log(err || 'Logged out');
  *    });
   * ```
   *
   * @param {String} accessTokenID
   * @callback {Function} callback
   * @param {Error} err
   */

  User.logout = function(tokenId, fn) {
    fn = fn || utils.createPromiseCallback();
    this.relations.accessTokens.modelTo.findById(tokenId, function(err, accessToken) {
      if (err) {
        fn(err);
      } else if (accessToken) {
        accessToken.destroy(fn);
      } else {
        fn(new Error('could not find accessToken'));
      }
    });
    return fn.promise;
  };

  /**
   * Compare the given `password` with the users hashed password.
   *
   * @param {String} password The plain text password
   * @returns {Boolean}
   */

  User.prototype.hasPassword = function(plain, fn) {
    fn = fn || utils.createPromiseCallback();
    if (this.password && plain) {
      bcrypt.compare(plain, this.password, function(err, isMatch) {
        if (err) return fn(err);
        fn(null, isMatch);
      });
    } else {
      fn(null, false);
    }
    return fn.promise;
  };

  /**
   * Verify a user's identity by sending them a confirmation email.
   *
   * ```js
   *    var options = {
   *      type: 'email',
   *      to: user.email,
   *      template: 'verify.ejs',
   *      redirect: '/',
   *      tokenGenerator: function (user, cb) { cb("random-token"); }
   *    };
   *
   *    user.verify(options, next);
   * ```
   *
   * @options {Object} options
   * @property {String} type Must be 'email'.
   * @property {String} to Email address to which verification email is sent.
   * @property {String} from Sender email addresss, for example
   *   `'noreply@myapp.com'`.
   * @property {String} subject Subject line text.
   * @property {String} text Text of email.
   * @property {String} template Name of template that displays verification
   *  page, for example, `'verify.ejs'.
   * @property {String} redirect Page to which user will be redirected after
   *  they verify their email, for example `'/'` for root URI.
   * @property {Function} generateVerificationToken A function to be used to
   *  generate the verification token. It must accept the user object and a
   *  callback function. This function should NOT add the token to the user
   *  object, instead simply execute the callback with the token! User saving
   *  and email sending will be handled in the `verify()` method.
   */

  User.prototype.verify = function(options, fn) {
    fn = fn || utils.createPromiseCallback();

    var user = this;
    var userModel = this.constructor;
    var registry = userModel.registry;
    assert(typeof options === 'object', 'options required when calling user.verify()');
    assert(options.type, 'You must supply a verification type (options.type)');
    assert(options.type === 'email', 'Unsupported verification type');
    assert(options.to || this.email, 'Must include options.to when calling user.verify() or the user must have an email property');
    assert(options.from, 'Must include options.from when calling user.verify() or the user must have an email property');

    options.redirect = options.redirect || '/';
    options.template = path.resolve(options.template || path.join(__dirname, '..', '..', 'templates', 'verify.ejs'));
    options.user = this;
    options.protocol = options.protocol || 'http';

    var app = userModel.app;
    options.host = options.host || (app && app.get('host')) || 'localhost';
    options.port = options.port || (app && app.get('port')) || 3000;
    options.restApiRoot = options.restApiRoot || (app && app.get('restApiRoot')) || '/api';
    options.verifyHref = options.verifyHref ||
      options.protocol +
      '://' +
      options.host +
      ':' +
      options.port +
      options.restApiRoot +
      userModel.http.path +
      userModel.sharedClass.find('confirm', true).http.path +
      '?uid=' +
      options.user.id +
      '&redirect=' +
      options.redirect;

    // Email model
    var Email = options.mailer || this.constructor.email || registry.getModelByType(loopback.Email);

    // Set a default token generation function if one is not provided
    var tokenGenerator = options.generateVerificationToken || User.generateVerificationToken;

    tokenGenerator(user, function(err, token) {
      if (err) { return fn(err); }

      user.verificationToken = token;
      user.save(function(err) {
        if (err) {
          fn(err);
        } else {
          sendEmail(user);
        }
      });
    });

    // TODO - support more verification types
    function sendEmail(user) {
      options.verifyHref += '&token=' + user.verificationToken;

      options.text = options.text || 'Please verify your email by opening this link in a web browser:\n\t{href}';

      options.text = options.text.replace('{href}', options.verifyHref);

      options.to = options.to || user.email;

      options.subject = options.subject || 'Thanks for Registering';

      options.headers = options.headers || {};

      var template = loopback.template(options.template);
      options.html = template(options);

      Email.send(options, function(err, email) {
        if (err) {
          fn(err);
        } else {
          fn(null, {email: email, token: user.verificationToken, uid: user.id});
        }
      });
    }
    return fn.promise;
  };

  /**
   * A default verification token generator which accepts the user the token is
   * being generated for and a callback function to indicate completion.
   * This one uses the crypto library and 64 random bytes (converted to hex)
   * for the token. When used in combination with the user.verify() method this
   * function will be called with the `user` object as it's context (`this`).
   *
   * @param {object} user The User this token is being generated for.
   * @param {Function} cb The generator must pass back the new token with this function call
   */
  User.generateVerificationToken = function(user, cb) {
    crypto.randomBytes(64, function(err, buf) {
      cb(err, buf && buf.toString('hex'));
    });
  };

  /**
   * Confirm the user's identity.
   *
   * @param {Any} userId
   * @param {String} token The validation token
   * @param {String} redirect URL to redirect the user to once confirmed
   * @callback {Function} callback
   * @param {Error} err
   */
  User.confirm = function(uid, token, redirect, fn) {
    fn = fn || utils.createPromiseCallback();
    this.findById(uid, function(err, user) {
      if (err) {
        fn(err);
      } else {
        if (user && user.verificationToken === token) {
          user.verificationToken = undefined;
          user.emailVerified = true;
          user.save(function(err) {
            if (err) {
              fn(err);
            } else {
              fn();
            }
          });
        } else {
          if (user) {
            err = new Error('Invalid token: ' + token);
            err.statusCode = 400;
            err.code = 'INVALID_TOKEN';
          } else {
            err = new Error('User not found: ' + uid);
            err.statusCode = 404;
            err.code = 'USER_NOT_FOUND';
          }
          fn(err);
        }
      }
    });
    return fn.promise;
  };

  /**
   * Create a short lived acess token for temporary login. Allows users
   * to change passwords if forgotten.
   *
   * @options {Object} options
   * @prop {String} email The user's email address
   * @callback {Function} callback
   * @param {Error} err
   */

  User.resetPassword = function(options, cb) {
    cb = cb || utils.createPromiseCallback();
    var UserModel = this;
    var ttl = UserModel.settings.resetPasswordTokenTTL || DEFAULT_RESET_PW_TTL;

    options = options || {};
    if (typeof options.email === 'string') {
      UserModel.findOne({ where: {email: options.email} }, function(err, user) {
        if (err) {
          cb(err);
        } else if (user) {
          // create a short lived access token for temp login to change password
          // TODO(ritch) - eventually this should only allow password change
          user.accessTokens.create({ttl: ttl}, function(err, accessToken) {
            if (err) {
              cb(err);
            } else {
              cb();
              UserModel.emit('resetPasswordRequest', {
                email: options.email,
                accessToken: accessToken,
                user: user
              });
            }
          });
        } else {
          cb();
        }
      });
    } else {
      var err = new Error('email is required');
      err.statusCode = 400;
      err.code = 'EMAIL_REQUIRED';
      cb(err);
    }
    return cb.promise;
  };

  /*!
   * Hash the plain password
   */
  User.hashPassword = function(plain) {
    this.validatePassword(plain);
    var salt = bcrypt.genSaltSync(this.settings.saltWorkFactor || SALT_WORK_FACTOR);
    return bcrypt.hashSync(plain, salt);
  };

  User.validatePassword = function(plain) {
    if (typeof plain === 'string' && plain) {
      return true;
    }
    var err =  new Error('Invalid password: ' + plain);
    err.statusCode = 422;
    throw err;
  };

  /*!
   * Setup an extended user model.
   */

  User.setup = function() {
    // We need to call the base class's setup method
    User.base.setup.call(this);
    var UserModel = this;

    // max ttl
    this.settings.maxTTL = this.settings.maxTTL || DEFAULT_MAX_TTL;
    this.settings.ttl = this.settings.ttl || DEFAULT_TTL;

    UserModel.setter.password = function(plain) {
      if (typeof plain !== 'string') {
        return;
      }
      if (plain.indexOf('$2a$') === 0 && plain.length === 60) {
        // The password is already hashed. It can be the case
        // when the instance is loaded from DB
        this.$password = plain;
      } else {
        this.$password = this.constructor.hashPassword(plain);
      }
    };

    // Make sure emailVerified is not set by creation
    UserModel.beforeRemote('create', function(ctx, user, next) {
      var body = ctx.req.body;
      if (body && body.emailVerified) {
        body.emailVerified = false;
      }
      next();
    });

    UserModel.remoteMethod(
      'login',
      {
        description: 'Login a user with username/email and password.',
        accepts: [
          {arg: 'credentials', type: 'object', required: true, http: {source: 'body'}},
          {arg: 'include', type: ['string'], http: {source: 'query' },
            description: 'Related objects to include in the response. ' +
            'See the description of return value for more details.'}
        ],
        returns: {
          arg: 'accessToken', type: 'object', root: true,
          description:
            'The response body contains properties of the AccessToken created on login.\n' +
            'Depending on the value of `include` parameter, the body may contain ' +
            'additional properties:\n\n' +
            '  - `user` - `{User}` - Data of the currently logged in user. (`include=user`)\n\n'
        },
        http: {verb: 'post'}
      }
    );

    UserModel.remoteMethod(
      'logout',
      {
        description: 'Logout a user with access token.',
        accepts: [
          {arg: 'access_token', type: 'string', required: true, http: function(ctx) {
            var req = ctx && ctx.req;
            var accessToken = req && req.accessToken;
            var tokenID = accessToken && accessToken.id;

            return tokenID;
          }, description: 'Do not supply this argument, it is automatically extracted ' +
            'from request headers.'
          }
        ],
        http: {verb: 'all'}
      }
    );

    UserModel.remoteMethod(
      'confirm',
      {
        description: 'Confirm a user registration with email verification token.',
        accepts: [
          {arg: 'uid', type: 'string', required: true},
          {arg: 'token', type: 'string', required: true},
          {arg: 'redirect', type: 'string'}
        ],
        http: {verb: 'get', path: '/confirm'}
      }
    );

    UserModel.remoteMethod(
      'resetPassword',
      {
        description: 'Reset password for a user with email.',
        accepts: [
          {arg: 'options', type: 'object', required: true, http: {source: 'body'}}
        ],
        http: {verb: 'post', path: '/reset'}
      }
    );

    UserModel.afterRemote('confirm', function(ctx, inst, next) {
      if (ctx.args.redirect !== undefined) {
        if (!ctx.res) {
          return next(new Error('The transport does not support HTTP redirects.'));
        }
        ctx.res.location(ctx.args.redirect);
        ctx.res.status(302);
      }
      next();
    });

    // default models
    assert(loopback.Email, 'Email model must be defined before User model');
    UserModel.email = loopback.Email;

    assert(loopback.AccessToken, 'AccessToken model must be defined before User model');
    UserModel.accessToken = loopback.AccessToken;

    // email validation regex
    var re = /^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;

    UserModel.validatesFormatOf('email', {with: re, message: 'Must provide a valid email'});

    // FIXME: We need to add support for uniqueness of composite keys in juggler
    if (!(UserModel.settings.realmRequired || UserModel.settings.realmDelimiter)) {
      UserModel.validatesUniquenessOf('email', {message: 'Email already exists'});
      UserModel.validatesUniquenessOf('username', {message: 'User already exists'});
    }

    return UserModel;
  };

  /*!
   * Setup the base user.
   */

  User.setup();

};
