CREATE TABLE IF NOT EXISTS gateway_request_assets (
  id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
  sha256 text NOT NULL,
  content_type text NOT NULL,
  byte_size bigint NOT NULL,
  url text NOT NULL,
  storage_provider text NOT NULL,
  local_path text,
  expires_at timestamptz,
  expired_at timestamptz,
  ref_count integer NOT NULL DEFAULT 0,
  created_at timestamptz NOT NULL DEFAULT now(),
  updated_at timestamptz NOT NULL DEFAULT now(),
  UNIQUE (sha256, content_type)
);

CREATE INDEX IF NOT EXISTS idx_gateway_request_assets_expires
  ON gateway_request_assets(storage_provider, expires_at)
  WHERE expires_at IS NOT NULL AND expired_at IS NULL;

CREATE INDEX IF NOT EXISTS idx_gateway_request_assets_local_path
  ON gateway_request_assets(local_path)
  WHERE local_path IS NOT NULL;

CREATE TABLE IF NOT EXISTS gateway_conversations (
  id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
  user_id text NOT NULL,
  gateway_user_id uuid REFERENCES gateway_users(id) ON DELETE SET NULL,
  conversation_key text NOT NULL,
  metadata jsonb NOT NULL DEFAULT '{}'::jsonb,
  created_at timestamptz NOT NULL DEFAULT now(),
  updated_at timestamptz NOT NULL DEFAULT now(),
  UNIQUE (user_id, conversation_key)
);

CREATE TABLE IF NOT EXISTS gateway_conversation_messages (
  id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
  conversation_id uuid NOT NULL REFERENCES gateway_conversations(id) ON DELETE CASCADE,
  message_hash text NOT NULL,
  role text,
  message_snapshot jsonb NOT NULL,
  asset_sha256s text[] NOT NULL DEFAULT '{}',
  created_at timestamptz NOT NULL DEFAULT now(),
  updated_at timestamptz NOT NULL DEFAULT now(),
  UNIQUE (conversation_id, message_hash)
);

CREATE INDEX IF NOT EXISTS idx_gateway_conversation_messages_conversation
  ON gateway_conversation_messages(conversation_id, created_at);

CREATE TABLE IF NOT EXISTS gateway_task_message_refs (
  task_id uuid NOT NULL REFERENCES gateway_tasks(id) ON DELETE CASCADE,
  message_id uuid NOT NULL REFERENCES gateway_conversation_messages(id) ON DELETE CASCADE,
  position integer NOT NULL,
  created_at timestamptz NOT NULL DEFAULT now(),
  PRIMARY KEY (task_id, position)
);

CREATE INDEX IF NOT EXISTS idx_gateway_task_message_refs_message
  ON gateway_task_message_refs(message_id);

ALTER TABLE gateway_tasks
  ADD COLUMN IF NOT EXISTS conversation_id uuid REFERENCES gateway_conversations(id) ON DELETE SET NULL,
  ADD COLUMN IF NOT EXISTS new_message_count integer NOT NULL DEFAULT 0;

CREATE INDEX IF NOT EXISTS idx_gateway_tasks_conversation_created
  ON gateway_tasks(conversation_id, created_at DESC)
  WHERE conversation_id IS NOT NULL;