discourse/app/controllers/session_controller.rb

class SessionController < ApplicationController

  def create
    requires_parameter(:login, :password)

    login = params[:login].downcase
    login = login[1..-1] if login[0] == "@"

    if login =~ /@/
      @user = User.where(email: login).first
    else
      @user = User.where(username_lower: login).first
    end

    if @user.present? 

      # If the site requires user approval and the user is not approved yet
      if SiteSetting.must_approve_users? and !@user.approved?
        render :json => {error: I18n.t("login.not_approved")}
        return
      end

      # If their password is correct
      if @user.confirm_password?(params[:password])
        log_on_user(@user)
        render_serialized(@user, UserSerializer)
        return
      end
    end

    render :json => {error: I18n.t("login.incorrect_username_email_or_password")}
  end

  # Retrieve information about the site and session
  def index
    render_serialized(DiscourseSession.new, DiscourseSessionSerializer)
  end

  def forgot_password
    requires_parameter(:username)

    user = User.where('username_lower = :username or email = :username', username: params[:username].downcase).first
    if user.present?
      email_token = user.email_tokens.create(email: user.email)
      Jobs.enqueue(:user_email, type: :forgot_password, user_id: user.id, email_token: email_token.token)
    end
    # always render of so we don't leak information
    render :json => {result: "ok"}
  end

  def destroy
    session[:current_user_id] = nil
    cookies[:_t] = nil
    render nothing: true
  end

end