CREATE TABLE IF NOT EXISTS im_conversations (
  id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  conversation_type TINYINT UNSIGNED NOT NULL DEFAULT 1,
  last_seq BIGINT UNSIGNED NOT NULL DEFAULT 0,
  last_message_id BIGINT UNSIGNED NULL,
  last_message_at DATETIME(3) NULL,
  status TINYINT UNSIGNED NOT NULL DEFAULT 1,
  created_at DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
  updated_at DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3) ON UPDATE CURRENT_TIMESTAMP(3),
  PRIMARY KEY (id),
  KEY idx_conversation_last (last_message_at)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE IF NOT EXISTS im_direct_conversations (
  conversation_id BIGINT UNSIGNED NOT NULL,
  user1_id BIGINT UNSIGNED NOT NULL,
  user2_id BIGINT UNSIGNED NOT NULL,
  created_at DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
  PRIMARY KEY (conversation_id),
  UNIQUE KEY uk_direct_pair (user1_id, user2_id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE IF NOT EXISTS im_conversation_members (
  conversation_id BIGINT UNSIGNED NOT NULL,
  user_id BIGINT UNSIGNED NOT NULL,
  join_seq BIGINT UNSIGNED NOT NULL DEFAULT 0,
  read_seq BIGINT UNSIGNED NOT NULL DEFAULT 0,
  delivered_seq BIGINT UNSIGNED NOT NULL DEFAULT 0,
  clear_seq BIGINT UNSIGNED NOT NULL DEFAULT 0,
  pinned TINYINT(1) NOT NULL DEFAULT 0,
  muted TINYINT(1) NOT NULL DEFAULT 0,
  status TINYINT UNSIGNED NOT NULL DEFAULT 1,
  joined_at DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
  updated_at DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3) ON UPDATE CURRENT_TIMESTAMP(3),
  PRIMARY KEY (conversation_id, user_id),
  KEY idx_member_user (user_id, updated_at)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE IF NOT EXISTS im_messages (
  id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  conversation_id BIGINT UNSIGNED NOT NULL,
  seq BIGINT UNSIGNED NOT NULL,
  sender_id BIGINT UNSIGNED NOT NULL,
  client_msg_id CHAR(26) CHARACTER SET ascii COLLATE ascii_bin NOT NULL,
  message_type SMALLINT UNSIGNED NOT NULL,
  body MEDIUMBLOB NOT NULL,
  reply_to_message_id BIGINT UNSIGNED NULL,
  moderation_status TINYINT UNSIGNED NOT NULL DEFAULT 1,
  recalled_at DATETIME(3) NULL,
  created_at DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
  PRIMARY KEY (id),
  UNIQUE KEY uk_conv_seq (conversation_id, seq),
  UNIQUE KEY uk_sender_client_msg (sender_id, client_msg_id),
  KEY idx_conv_created (conversation_id, created_at)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE IF NOT EXISTS im_user_sync_events (
  user_id BIGINT UNSIGNED NOT NULL,
  event_seq BIGINT UNSIGNED NOT NULL,
  event_type SMALLINT UNSIGNED NOT NULL,
  conversation_id BIGINT UNSIGNED NOT NULL,
  message_seq BIGINT UNSIGNED NOT NULL,
  event_data MEDIUMBLOB NULL,
  created_at DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
  PRIMARY KEY (user_id, event_seq),
  KEY idx_sync_created (created_at)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;