// Phase 7 UX — per-user deletion modes, per-user chat state, folders + pins.
//
// All of this is per-user *view* state (Telegram semantics): hiding a message
// or clearing a chat never mutates the shared message rows; it records what
// this user no longer sees. Folders and pins are per-user and server-stored so
// they sync across devices via the personal channel.

/** @param {import('node-pg-migrate').MigrationBuilder} pgm */
exports.up = (pgm) => {
  // "Delete for me": tombstone per (user, message). History queries anti-join.
  pgm.createTable('message_hidden', {
    user_id: { type: 'uuid', notNull: true, references: 'users', onDelete: 'CASCADE' },
    message_id: { type: 'uuid', notNull: true, references: 'messages', onDelete: 'CASCADE' },
    created_at: { type: 'timestamptz', notNull: true, default: pgm.func('now()') },
  });
  pgm.addConstraint('message_hidden', 'message_hidden_pkey', {
    primaryKey: ['user_id', 'message_id'],
  });

  // "Clear history" / "delete chat" for me. Messages with seq <= cleared_up_to_seq
  // are invisible to this member. hidden_at removes the chat from the list until
  // new activity arrives (last_message_at > hidden_at brings it back).
  pgm.addColumns('conversation_members', {
    cleared_up_to_seq: { type: 'bigint', notNull: true, default: 0 },
    hidden_at: { type: 'timestamptz' },
  });

  // Manual chat folders (per user), ordered by position.
  pgm.createTable('chat_folders', {
    id: { type: 'uuid', notNull: true, default: pgm.func('gen_random_uuid()'), primaryKey: true },
    user_id: { type: 'uuid', notNull: true, references: 'users', onDelete: 'CASCADE' },
    title: { type: 'text', notNull: true },
    position: { type: 'integer', notNull: true, default: 0 },
    created_at: { type: 'timestamptz', notNull: true, default: pgm.func('now()') },
  });
  pgm.createIndex('chat_folders', 'user_id');

  pgm.createTable('chat_folder_items', {
    folder_id: { type: 'uuid', notNull: true, references: 'chat_folders', onDelete: 'CASCADE' },
    conversation_id: {
      type: 'uuid',
      notNull: true,
      references: 'conversations',
      onDelete: 'CASCADE',
    },
    created_at: { type: 'timestamptz', notNull: true, default: pgm.func('now()') },
  });
  pgm.addConstraint('chat_folder_items', 'chat_folder_items_pkey', {
    primaryKey: ['folder_id', 'conversation_id'],
  });

  // Pins are scoped: folder_id NULL = pinned in the "All chats" tab. Pinning in
  // one folder deliberately does not pin anywhere else.
  pgm.createTable('chat_pins', {
    user_id: { type: 'uuid', notNull: true, references: 'users', onDelete: 'CASCADE' },
    conversation_id: {
      type: 'uuid',
      notNull: true,
      references: 'conversations',
      onDelete: 'CASCADE',
    },
    folder_id: { type: 'uuid', references: 'chat_folders', onDelete: 'CASCADE' },
    pinned_at: { type: 'timestamptz', notNull: true, default: pgm.func('now()') },
  });
  // Uniqueness needs two partial indexes because folder_id is nullable.
  pgm.createIndex('chat_pins', ['user_id', 'conversation_id'], {
    name: 'chat_pins_all_scope_unique',
    unique: true,
    where: 'folder_id IS NULL',
  });
  pgm.createIndex('chat_pins', ['user_id', 'conversation_id', 'folder_id'], {
    name: 'chat_pins_folder_scope_unique',
    unique: true,
    where: 'folder_id IS NOT NULL',
  });
  pgm.createIndex('chat_pins', 'user_id');
};

/** @param {import('node-pg-migrate').MigrationBuilder} pgm */
exports.down = (pgm) => {
  pgm.dropTable('chat_pins');
  pgm.dropTable('chat_folder_items');
  pgm.dropTable('chat_folders');
  pgm.dropColumns('conversation_members', ['cleared_up_to_seq', 'hidden_at']);
  pgm.dropTable('message_hidden');
};