module Gmail
  class Client
    # Raised when connection with GMail IMAP service couldn't be established. 
    class ConnectionError < SocketError; end
    # Raised when given username or password are invalid.
    class AuthorizationError < Net::IMAP::NoResponseError; end
    # Raised when delivered email is invalid. 
    class DeliveryError < ArgumentError; end
  
    # GMail IMAP defaults
    GMAIL_IMAP_HOST = 'imap.gmail.com'
    GMAIL_IMAP_PORT = 993
    
    # GMail SMTP defaults
    GMAIL_SMTP_HOST = "smtp.gmail.com"
    GMAIL_SMTP_PORT = 587
  
    attr_reader :email
    attr_reader :token
    attr_reader :secret
    attr_reader :options
  
    def initialize(email, token, secret, consumer_key, consumer_secret, options={})
      defaults  = {}
      @email = email
      @username = email
      @token = token
      @secret = secret
      @consumer_key = consumer_key
      @consumer_secret = consumer_secret
      @options  = defaults.merge(options)
    end
    
    # Connect to gmail service. 
    def connect(raise_errors=false)
      @imap = Net::IMAP.new(GMAIL_IMAP_HOST, GMAIL_IMAP_PORT, true, nil, false)
    rescue SocketError
      raise_errors and raise ConnectionError, "Couldn't establish connection with GMail IMAP service"
    end
    
    # This version of connect will raise error on failure...
    def connect!
      connect(true)
    end
    
    # Return current connection. Log in automaticaly to specified account if 
    # it is necessary.
    def connection
      login and at_exit { logout } unless logged_in?
      @imap
    end
    alias :conn :connection
    
    # Login to specified account.
    def login(raise_errors=false)
      @imap and @logged_in = (login = @imap.authenticate('XOAUTH', @email,
        :consumer_key => @consumer_key,
        :consumer_secret => @consumer_secret,
        :token => @token,
        :token_secret => @secret
      )) && login.name == 'OK'
    rescue Net::IMAP::NoResponseError
      raise_errors and raise AuthorizationError, "Couldn't login to given GMail account"
    end
    alias :sign_in :login
    
    # This version of login will raise error on failure...
    def login!
      login(true)
    end
    alias :sign_in! :login!
    
    # Returns +true+ when you are logged in to specified account.
    def logged_in?
      !!@logged_in
    end
    alias :signed_in? :logged_in?
    
    # Logout from GMail service. 
    def logout
      @imap && logged_in? and @imap.logout
    ensure
      @logged_in = false
    end
    alias :sign_out :logout
    
    # Return labels object, which helps you with managing your GMail labels.
    # See <tt>Gmail::Labels</tt> for details.
    def labels
      @labels ||= Labels.new(conn)
    end
    
    # Compose new e-mail.
    #
    # ==== Examples
    #   
    #   mail = gmail.compose
    #   mail.from "test@gmail.org"
    #   mail.to "friend@gmail.com"
    #
    # ... or block style:
    #  
    #   mail = gmail.compose do 
    #     from "test@gmail.org"
    #     to "friend@gmail.com"
    #     subject "Hello!"
    #     body "Hello my friend! long time..."
    #   end
    #
    # Now you can deliver your mail:
    #
    #   gmail.deliver(mail)
    def compose(mail=nil, &block)
      if block_given?
        mail = Mail.new(&block)
      elsif !mail 
        mail = Mail.new
      end 
      mail.delivery_method(*smtp_settings)
      mail.from = @email unless mail.from
      mail
    end
    alias :message :compose
    
    # Compose (optionaly) and send given email. 
    #
    # ==== Examples
    #
    #   gmail.deliver do 
    #     to "friend@gmail.com"
    #     subject "Hello friend!"
    #     body "Hi! How are you?"
    #   end
    #
    # ... or with already created message:
    #
    #   mail = Mail.new { ... }
    #   gmail.deliver(mail)
    #
    #   mail = gmail.compose { ... }
    #   gmail.deliver(mail)
    def deliver(mail=nil, raise_errors=false, &block)
      mail = compose(mail, &block) if block_given?
      mail.deliver!
    rescue Object => ex
      raise_errors and raise DeliveryError, "Couldn't deliver email: #{ex.to_s}"
    end
    
    # This version of deliver will raise error on failure...
    def deliver!(mail=nil, &block)
      deliver(mail, true, &block)
    end
    
    # Do something with given mailbox or within it context. 
    #
    # ==== Examples
    #
    #   mailbox = gmail.mailbox("INBOX")
    #   mailbox.emails(:all)
    #   mailbox.count(:unread, :before => Time.now-(20*24*3600))
    #
    # ... or block style:
    #
    #   gmail.label("Work") do |mailbox|
    #     mailbox.emails(:unread)
    #     mailbox.count(:all)
    #     ...
    #   end
    def mailbox(name, &block)
      name = Net::IMAP.encode_utf7(name.to_s)
      mailbox = (mailboxes[name] ||= Mailbox.new(self, name))
      switch_to_mailbox(name) if @current_mailbox != name
      if block_given?
        mailbox_stack << @current_mailbox
        result = block.arity == 1 ? block.call(mailbox) : block.call
        mailbox_stack.pop
        switch_to_mailbox(mailbox_stack.last)
        return result
      end
      mailbox
    end
    alias :in_mailbox :mailbox
    alias :in_label :mailbox
    alias :label :mailbox
    
    # Alias for <tt>mailbox("INBOX")</tt>. See <tt>Gmail::Client#mailbox</tt>
    # for details.
    def inbox
      mailbox("INBOX")
    end
    
    def mailboxes
      @mailboxes ||= {}
    end
    
    def inspect
      "#<Gmail::Client#{'0x%04x' % (object_id << 1)} (#{@email}) #{'dis' if !logged_in?}connected>"
    end
    
    #def fill_username(username)
    #  username =~ /@/ ? username : "#{username}@gmail.com"
    #end

    def mail_domain
      @email.split('@')[0]
    end
    
    private
    
    def switch_to_mailbox(mailbox)
      conn.select(mailbox) if mailbox
      @current_mailbox = mailbox
    end
    
    def mailbox_stack
      @mailbox_stack ||= []
    end
    
    def smtp_settings
      [:smtp, {
        :address => GMAIL_SMTP_HOST,
        :port => GMAIL_SMTP_PORT,
        :domain => mail_domain,
        :user_name => username,
        :password => secret = {
          :consumer_key => 'anonymous',
          :consumer_secret => 'anonymous',
          :token => '4/nM2QAaunKUINb4RrXPC55F-mix_k',
          :token_secret => '41r18IyXjIvuyabS/NDyW6+m'
        },
        :authentication => :xoauth,
        :enable_starttls_auto => true
      }]
    end
  end # Client
end # Gmail