-- ============================================================
-- Migration 015: Presenca do agente e reserva de chamados em pausa
-- Tabelas:
--   agent_presence
--   whatsapp_chat_atribuicoes
-- ============================================================

CREATE TABLE IF NOT EXISTS agent_presence (
  user_id INTEGER PRIMARY KEY REFERENCES usuarios(id) ON DELETE CASCADE,
  status VARCHAR(40) NOT NULL DEFAULT 'offline',
  paused_at TIMESTAMP WITH TIME ZONE,
  last_seen_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
  updated_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
);

DO $$
BEGIN
  IF NOT EXISTS (
    SELECT 1
    FROM pg_constraint
    WHERE conname = 'chk_agent_presence_status'
  ) THEN
    ALTER TABLE agent_presence
      ADD CONSTRAINT chk_agent_presence_status
      CHECK (status IN ('available', 'paused', 'offline'));
  END IF;
END $$;

INSERT INTO agent_presence (user_id, status, last_seen_at, updated_at)
SELECT id, 'available', CURRENT_TIMESTAMP, CURRENT_TIMESTAMP
FROM usuarios
ON CONFLICT (user_id) DO NOTHING;

ALTER TABLE whatsapp_chat_atribuicoes
  ADD COLUMN IF NOT EXISTS reserved_user_id INTEGER REFERENCES usuarios(id) ON DELETE SET NULL,
  ADD COLUMN IF NOT EXISTS reserved_at TIMESTAMP WITH TIME ZONE,
  ADD COLUMN IF NOT EXISTS pause_released_at TIMESTAMP WITH TIME ZONE;

CREATE INDEX IF NOT EXISTS idx_agent_presence_status
  ON agent_presence (status);

CREATE INDEX IF NOT EXISTS idx_agent_presence_paused_at
  ON agent_presence (paused_at)
  WHERE status = 'paused';

CREATE INDEX IF NOT EXISTS idx_whatsapp_atribuicoes_reserved_user
  ON whatsapp_chat_atribuicoes (reserved_user_id, status)
  WHERE reserved_user_id IS NOT NULL;

CREATE INDEX IF NOT EXISTS idx_whatsapp_atribuicoes_reserved_queue
  ON whatsapp_chat_atribuicoes (area_id, status, reserved_user_id)
  WHERE status = 'queued';