require 'sendgrid_actionmailer/version'
require 'sendgrid_actionmailer/railtie' if defined? Rails
require 'sendgrid-ruby'

module SendGridActionMailer
  class DeliveryMethod

    # TODO: use custom class to customer excpetion payload
    SendgridDeliveryError = Class.new(StandardError)

    include SendGrid

    DEFAULTS = {
      raise_delivery_errors: false
    }.freeze

    attr_accessor :settings, :api_key

    def initialize(**params)
      self.settings = DEFAULTS.merge(params)
    end

    def deliver!(mail)
      sendgrid_mail = Mail.new.tap do |m|
        m.from = to_email(mail.from)
        m.reply_to = to_email(mail.reply_to)
        m.subject = mail.subject || ""
      end

      add_personalizations(sendgrid_mail, mail)
      add_api_key(sendgrid_mail, mail)
      add_content(sendgrid_mail, mail)
      add_send_options(sendgrid_mail, mail)
      add_mail_settings(sendgrid_mail, mail)
      add_tracking_settings(sendgrid_mail, mail)

      response = perform_send_request(sendgrid_mail)

      settings[:return_response] ? response : self
    end

    private

    def client
      @client = SendGrid::API.new(api_key: api_key).client
    end

    # type should be either :plain or :html
    def to_content(type, value)
      Content.new(type: "text/#{type}", value: value)
    end

    def to_email(input)
      to_emails(input).first
    end

    def to_emails(input)
      if input.is_a?(String)
        [Email.new(email: input)]
      elsif input.is_a?(::Mail::AddressContainer) && !input.instance_variable_get('@field').nil?
        input.instance_variable_get('@field').addrs.map do |addr| # Mail::Address
          Email.new(email: addr.address, name: addr.name)
        end
      elsif input.is_a?(::Mail::AddressContainer)
        input.map do |addr|
          Email.new(email: addr)
        end
      elsif input.is_a?(::Mail::StructuredField)
        [Email.new(email: input.value)]
      elsif input.nil?
        []
      else
        puts "unknown type #{input.class.name}"
      end
    end

    def setup_personalization(mail, personalization_hash)
      personalization = Personalization.new

      personalization_hash =  self.class.transform_keys(personalization_hash, &:to_s)

      (personalization_hash['to'] || []).each do |to|
        personalization.add_to Email.new(email: to['email'], name: to['name'])
      end
      (personalization_hash['cc'] || []).each do |cc|
        personalization.add_cc Email.new(email: cc['email'], name: cc['name'])
      end
      (personalization_hash['bcc'] || []).each do |bcc|
        personalization.add_bcc Email.new(email: bcc['email'], name: bcc['name'])
      end
      (personalization_hash['headers'] || []).each do |header_key, header_value|
        personalization.add_header Header.new(key: header_key, value: header_value)
      end
      (personalization_hash['substitutions'] || {}).each do |sub_key, sub_value|
        personalization.add_substitution(Substitution.new(key: sub_key, value: sub_value))
      end
      (personalization_hash['custom_args'] || {}).each do |arg_key, arg_value|
        personalization.add_custom_arg(CustomArg.new(key: arg_key, value: arg_value))
      end
      if personalization_hash['send_at']
        personalization.send_at = personalization_hash['send_at']
      end
      if personalization_hash['subject']
        personalization.subject = personalization_hash['subject']
      end

      if mail['dynamic_template_data'] || personalization_hash['dynamic_template_data']
        if mail['dynamic_template_data']
          data = mail['dynamic_template_data'].unparsed_value
          data.merge!(personalization_hash['dynamic_template_data'] || {})
        else
          data = personalization_hash['dynamic_template_data']
        end
        personalization.add_dynamic_template_data(data)
      elsif mail['template_id'].nil?
        personalization.add_substitution(Substitution.new(key: "%asm_group_unsubscribe_raw_url%", value: "<%asm_group_unsubscribe_raw_url%>"))
        personalization.add_substitution(Substitution.new(key: "%asm_global_unsubscribe_raw_url%", value: "<%asm_global_unsubscribe_raw_url%>"))
        personalization.add_substitution(Substitution.new(key: "%asm_preferences_raw_url%", value: "<%asm_preferences_raw_url%>"))
      end

      return personalization
    end

    def to_attachment(part)
      Attachment.new.tap do |a|
        a.content = Base64.strict_encode64(part.body.decoded)
        a.type = part.mime_type
        a.filename = part.filename

        disposition = get_disposition(part)
        a.disposition = disposition unless disposition.nil?

        has_content_id = part.header && part.has_content_id?
        a.content_id = part.header['content_id'].value if has_content_id
      end
    end

    def get_disposition(message)
      return if message.header.nil?
      content_disp = message.header[:content_disposition]
      return unless content_disp.respond_to?(:disposition_type)
      content_disp.disposition_type
    end

    def add_api_key(sendgrid_mail, mail)
      self.api_key = settings.fetch(:api_key)
      if mail['delivery-method-options'] && mail['delivery-method-options'].value.include?('api_key')
        self.api_key = mail['delivery-method-options'].unparsed_value['api_key']
      end
    end

    def add_attachments(sendgrid_mail, mail)
      mail.attachments.each do |part|
        sendgrid_mail.add_attachment(to_attachment(part))
      end
    end

    def add_content(sendgrid_mail, mail)
      if mail['template_id']
        # We are sending a template, so we don't need to add any content outside
        # of attachments
        add_attachments(sendgrid_mail, mail)
      else
        case mail.mime_type
        when 'text/plain'
          sendgrid_mail.add_content(to_content(:plain, mail.body.decoded))
        when 'text/html'
          sendgrid_mail.add_content(to_content(:html, mail.body.decoded))
        when 'multipart/alternative', 'multipart/mixed', 'multipart/related'
          sendgrid_mail.add_content(to_content(:plain, mail.text_part.decoded)) if mail.text_part
          sendgrid_mail.add_content(to_content(:html, mail.html_part.decoded)) if mail.html_part

          add_attachments(sendgrid_mail, mail)
        end
      end
    end

    def add_personalizations(sendgrid_mail, mail)
      if mail['personalizations']
        mail['personalizations'].unparsed_value.each do |p|
          sendgrid_mail.add_personalization(setup_personalization(mail, p))
        end
      end
      if (mail.to && mail.to.any?) || (mail.cc && mail.cc.any?) || (mail.bcc && mail.bcc.any?)
        personalization = setup_personalization(mail, {})
        to_emails(mail.to).each { |to| personalization.add_to(to) }
        to_emails(mail.cc).each { |cc| personalization.add_cc(cc) }
        to_emails(mail.bcc).each { |bcc| personalization.add_bcc(bcc) }
        sendgrid_mail.add_personalization(personalization)
      end
    end

    def add_send_options(sendgrid_mail, mail)
      if mail['template_id']
         sendgrid_mail.template_id = mail['template_id'].to_s
      end
      if mail['sections']
        mail['sections'].unparsed_value.each do |key, value|
          sendgrid_mail.add_section(Section.new(key: key, value: value))
        end
      end
      if mail['headers']
        mail['headers'].unparsed_value.each do |key, value|
          sendgrid_mail.add_header(Header.new(key: key, value: value))
        end
      end
      if mail['categories']
        mail['categories'].value.split(",").each do |value|
          sendgrid_mail.add_category(Category.new(name: value.strip))
        end
      end
      if mail['custom_args']
        mail['custom_args'].unparsed_value.each do |key, value|
          sendgrid_mail.add_custom_arg(CustomArg.new(key: key, value: value))
        end
      end
      if mail['send_at']
        sendgrid_mail.send_at = mail['send_at'].value.to_i
      end
      if mail['batch_id']
        sendgrid_mail.batch_id = mail['batch_id'].to_s
      end
      if mail['asm']
        asm = mail['asm'].unparsed_value
        asm =  asm.delete_if { |key, value| 
          !key.to_s.match(/(group_id)|(groups_to_display)/) }
        if asm.keys.map(&:to_s).include?('group_id')
          sendgrid_mail.asm = ASM.new(asm)
        end
      end
      if mail['ip_pool_name']
        sendgrid_mail.ip_pool_name = mail['ip_pool_name'].to_s
      end
    end

    def add_mail_settings(sendgrid_mail, mail)
      if mail['mail_settings']
        settings = mail['mail_settings'].unparsed_value || {}
        sendgrid_mail.mail_settings = MailSettings.new.tap do |m|
          if settings[:bcc]
            m.bcc = BccSettings.new(settings[:bcc])
          end
          if settings[:bypass_list_management]
            m.bypass_list_management = BypassListManagement.new(settings[:bypass_list_management])
          end
          if settings[:footer]
            m.footer = Footer.new(settings[:footer])
          end
          if settings[:sandbox_mode]
            m.sandbox_mode = SandBoxMode.new(settings[:sandbox_mode])
          end
          if settings[:spam_check]
            m.spam_check = SpamCheck.new(settings[:spam_check])
          end
        end
      end
    end

    def add_tracking_settings(sendgrid_mail, mail)
      if mail['tracking_settings']
        settings = mail['tracking_settings'].unparsed_value
        sendgrid_mail.tracking_settings = TrackingSettings.new.tap do |t|
          if settings[:click_tracking]
            t.click_tracking = ClickTracking.new(settings[:click_tracking])
          end
          if settings[:open_tracking]
            t.open_tracking = OpenTracking.new(settings[:open_tracking])
          end
          if settings[:subscription_tracking]
            t.subscription_tracking = SubscriptionTracking.new(settings[:subscription_tracking])
          end
          if settings[:ganalytics]
            t.ganalytics = Ganalytics.new(settings[:ganalytics])
          end
        end
      end
    end

    def perform_send_request(email)
      result = client.mail._('send').post(request_body: email.to_json) # ლ(ಠ益ಠლ) that API

      if result.status_code && result.status_code.start_with?('4')
        message = !!(result.body) ? JSON.parse(result.body).fetch('errors').pop.fetch('message') : 'Sendgrid API Error'
        full_message = "Sendgrid delivery failed with #{result.status_code} #{message}"

        settings[:raise_delivery_errors] ? raise(SendgridDeliveryError, full_message) : warn(full_message)
      end

      result
    end

    # Recursive key transformation based on Rails deep_transform_values
    def self.transform_keys(object, &block)
      case object
      when Hash
        object.map { |key, value| [yield(key), transform_keys(value, &block)] }.to_h
      when Array
        object.map { |e| transform_keys(e, &block) }
      else
        object
      end
    end
  end
end