require "json"
require "mail"
require "sqlite3"

module MailCatcher::Mail extend self
  def db
    @__db ||= begin
      SQLite3::Database.new(":memory:", :type_translation => true).tap do |db|
        db.execute(<<-SQL)
          CREATE TABLE message (
            id INTEGER PRIMARY KEY ASC,
            sender TEXT,
            recipients TEXT,
            subject TEXT,
            source BLOB,
            size TEXT,
            type TEXT,
            created_at DATETIME DEFAULT CURRENT_DATETIME
          )
        SQL
        db.execute(<<-SQL)
          CREATE TABLE message_part (
            id INTEGER PRIMARY KEY ASC,
            message_id INTEGER NOT NULL,
            cid TEXT,
            type TEXT,
            is_attachment INTEGER,
            filename TEXT,
            charset TEXT,
            body BLOB,
            size INTEGER,
            created_at DATETIME DEFAULT CURRENT_DATETIME
          )
        SQL
      end
    end
  end

  def add_message(from:, to:, data:)
    @add_message_query ||= db.prepare("INSERT INTO message (sender, recipients, subject, source, type, size, created_at) VALUES (?, ?, ?, ?, ?, ?, datetime('now'))")

    mail = Mail.new(data)
    @add_message_query.execute(from, JSON.generate(to), mail.subject, data, mail.mime_type || "text/plain", data.length)
    message_id = db.last_insert_row_id
    parts = mail.all_parts
    parts = [mail] if parts.empty?
    parts.each do |part|
      body = part.body.to_s
      # Only parts have CIDs, not mail
      cid = part.cid if part.respond_to? :cid
      add_message_part(message_id, cid, part.mime_type || "text/plain", part.attachment? ? 1 : 0, part.filename, part.charset, body, body.length)
    end
  end

  def add_message_part(*args)
    @add_message_part_query ||= db.prepare "INSERT INTO message_part (message_id, cid, type, is_attachment, filename, charset, body, size, created_at) VALUES (?, ?, ?, ?, ?, ?, ?, ?, datetime('now'))"
    @add_message_part_query.execute(*args)
  end

  def latest_created_at
    @latest_created_at_query ||= db.prepare "SELECT created_at FROM message ORDER BY created_at DESC LIMIT 1"
    @latest_created_at_query.execute.next
  end

  def messages
    @messages_query ||= db.prepare "SELECT id, sender, recipients, subject, size, created_at FROM message ORDER BY created_at, id ASC"
    @messages_query.execute.map do |row|
      Hash[row.fields.zip(row)].tap do |message|
        message["recipients"] &&= JSON.parse(message["recipients"])
      end
    end
  end

  def message(id)
    @message_query ||= db.prepare "SELECT * FROM message WHERE id = ? LIMIT 1"
    row = @message_query.execute(id).next
    row && Hash[row.fields.zip(row)].tap do |message|
      message["recipients"] &&= JSON.parse(message["recipients"])
    end
  end

  def message_has_html?(id)
    @message_has_html_query ||= db.prepare "SELECT 1 FROM message_part WHERE message_id = ? AND is_attachment = 0 AND type IN ('application/xhtml+xml', 'text/html') LIMIT 1"
    (!!@message_has_html_query.execute(id).next) || ["text/html", "application/xhtml+xml"].include?(message(id)["type"])
  end

  def message_has_plain?(id)
    @message_has_plain_query ||= db.prepare "SELECT 1 FROM message_part WHERE message_id = ? AND is_attachment = 0 AND type = 'text/plain' LIMIT 1"
    (!!@message_has_plain_query.execute(id).next) || message(id)["type"] == "text/plain"
  end

  def message_parts(id)
    @message_parts_query ||= db.prepare "SELECT cid, type, filename, size FROM message_part WHERE message_id = ? ORDER BY filename ASC"
    @message_parts_query.execute(id).map do |row|
      Hash[row.fields.zip(row)]
    end
  end

  def message_attachments(id)
    @message_parts_query ||= db.prepare "SELECT cid, type, filename, size FROM message_part WHERE message_id = ? AND is_attachment = 1 ORDER BY filename ASC"
    @message_parts_query.execute(id).map do |row|
      Hash[row.fields.zip(row)]
    end
  end

  def message_part(message_id, part_id)
    @message_part_query ||= db.prepare "SELECT * FROM message_part WHERE message_id = ? AND id = ? LIMIT 1"
    row = @message_part_query.execute(message_id, part_id).next
    row && Hash[row.fields.zip(row)]
  end

  def message_part_type(message_id, part_type)
    @message_part_type_query ||= db.prepare "SELECT * FROM message_part WHERE message_id = ? AND type = ? AND is_attachment = 0 LIMIT 1"
    row = @message_part_type_query.execute(message_id, part_type).next
    row && Hash[row.fields.zip(row)]
  end

  def message_part_html(message_id)
    part = message_part_type(message_id, "text/html")
    part ||= message_part_type(message_id, "application/xhtml+xml")
    part ||= begin
      message = message(message_id)
      message if message and ["text/html", "application/xhtml+xml"].include? message["type"]
    end
  end

  def message_part_plain(message_id)
    message_part_type message_id, "text/plain"
  end

  def message_part_cid(message_id, cid)
    @message_part_cid_query ||= db.prepare "SELECT * FROM message_part WHERE message_id = ?"
    @message_part_cid_query.execute(message_id).map do |row|
      Hash[row.fields.zip(row)]
    end.find do |part|
      part["cid"] == cid
    end
  end

  def delete!
    @delete_all_messages_query ||= db.prepare "DELETE FROM message"
    @delete_all_message_parts_query ||= db.prepare "DELETE FROM message_part"

    @delete_all_messages_query.execute and
    @delete_all_message_parts_query.execute
  end

  def delete_message!(message_id)
    @delete_messages_query ||= db.prepare "DELETE FROM message WHERE id = ?"
    @delete_message_parts_query ||= db.prepare "DELETE FROM message_part WHERE message_id = ?"
    @delete_messages_query.execute(message_id) and
    @delete_message_parts_query.execute(message_id)
  end
end