-- Migration 076: Worker Registry for Dynamic Workers
-- Workers register on startup, receive a friendly name, and report heartbeats

-- Name pool for workers (expandable, no hardcoding)
CREATE TABLE IF NOT EXISTS worker_name_pool (
  id SERIAL PRIMARY KEY,
  name VARCHAR(50) UNIQUE NOT NULL,
  in_use BOOLEAN DEFAULT FALSE,
  assigned_to VARCHAR(100), -- worker_id
  assigned_at TIMESTAMPTZ,
  created_at TIMESTAMPTZ DEFAULT NOW()
);

-- Seed with initial names (can add more via API)
INSERT INTO worker_name_pool (name) VALUES
  ('Alice'), ('Bella'), ('Clara'), ('Diana'), ('Elena'),
  ('Fiona'), ('Grace'), ('Hazel'), ('Iris'), ('Julia'),
  ('Katie'), ('Luna'), ('Mia'), ('Nora'), ('Olive'),
  ('Pearl'), ('Quinn'), ('Rosa'), ('Sara'), ('Tara'),
  ('Uma'), ('Vera'), ('Wendy'), ('Xena'), ('Yuki'), ('Zara'),
  ('Amber'), ('Blake'), ('Coral'), ('Dawn'), ('Echo'),
  ('Fleur'), ('Gem'), ('Haven'), ('Ivy'), ('Jade'),
  ('Kira'), ('Lotus'), ('Maple'), ('Nova'), ('Onyx'),
  ('Pixel'), ('Quest'), ('Raven'), ('Sage'), ('Terra'),
  ('Unity'), ('Violet'), ('Willow'), ('Xylo'), ('Yara'), ('Zen')
ON CONFLICT (name) DO NOTHING;

-- Worker registry - tracks active workers
CREATE TABLE IF NOT EXISTS worker_registry (
  id SERIAL PRIMARY KEY,
  worker_id VARCHAR(100) UNIQUE NOT NULL,  -- e.g., "pod-abc123" or uuid
  friendly_name VARCHAR(50),                -- assigned from pool
  role VARCHAR(50) NOT NULL,                -- task role
  pod_name VARCHAR(100),                    -- k8s pod name
  hostname VARCHAR(100),                    -- machine hostname
  ip_address VARCHAR(50),                   -- worker IP
  status VARCHAR(20) DEFAULT 'starting',    -- starting, active, idle, offline, terminated
  started_at TIMESTAMPTZ DEFAULT NOW(),
  last_heartbeat_at TIMESTAMPTZ DEFAULT NOW(),
  last_task_at TIMESTAMPTZ,
  tasks_completed INTEGER DEFAULT 0,
  tasks_failed INTEGER DEFAULT 0,
  current_task_id INTEGER,
  metadata JSONB DEFAULT '{}',
  created_at TIMESTAMPTZ DEFAULT NOW(),
  updated_at TIMESTAMPTZ DEFAULT NOW()
);

-- Indexes for worker registry
CREATE INDEX IF NOT EXISTS idx_worker_registry_status ON worker_registry(status);
CREATE INDEX IF NOT EXISTS idx_worker_registry_role ON worker_registry(role);
CREATE INDEX IF NOT EXISTS idx_worker_registry_heartbeat ON worker_registry(last_heartbeat_at);

-- Function to assign a name to a new worker
CREATE OR REPLACE FUNCTION assign_worker_name(p_worker_id VARCHAR(100))
RETURNS VARCHAR(50) AS $$
DECLARE
  v_name VARCHAR(50);
BEGIN
  -- Try to get an unused name
  UPDATE worker_name_pool
  SET in_use = TRUE, assigned_to = p_worker_id, assigned_at = NOW()
  WHERE id = (
    SELECT id FROM worker_name_pool
    WHERE in_use = FALSE
    ORDER BY RANDOM()
    LIMIT 1
    FOR UPDATE SKIP LOCKED
  )
  RETURNING name INTO v_name;

  -- If no names available, generate one
  IF v_name IS NULL THEN
    v_name := 'Worker-' || SUBSTRING(p_worker_id FROM 1 FOR 8);
  END IF;

  RETURN v_name;
END;
$$ LANGUAGE plpgsql;

-- Function to release a worker's name back to the pool
CREATE OR REPLACE FUNCTION release_worker_name(p_worker_id VARCHAR(100))
RETURNS VOID AS $$
BEGIN
  UPDATE worker_name_pool
  SET in_use = FALSE, assigned_to = NULL, assigned_at = NULL
  WHERE assigned_to = p_worker_id;
END;
$$ LANGUAGE plpgsql;

-- Function to mark stale workers as offline
CREATE OR REPLACE FUNCTION mark_stale_workers(stale_threshold_minutes INTEGER DEFAULT 5)
RETURNS INTEGER AS $$
DECLARE
  v_count INTEGER;
BEGIN
  UPDATE worker_registry
  SET status = 'offline', updated_at = NOW()
  WHERE status IN ('active', 'idle', 'starting')
    AND last_heartbeat_at < NOW() - (stale_threshold_minutes || ' minutes')::INTERVAL
  RETURNING COUNT(*) INTO v_count;

  -- Release names from offline workers
  PERFORM release_worker_name(worker_id)
  FROM worker_registry
  WHERE status = 'offline'
    AND last_heartbeat_at < NOW() - INTERVAL '30 minutes';

  RETURN COALESCE(v_count, 0);
END;
$$ LANGUAGE plpgsql;

-- View for dashboard
CREATE OR REPLACE VIEW v_active_workers AS
SELECT
  wr.id,
  wr.worker_id,
  wr.friendly_name,
  wr.role,
  wr.status,
  wr.pod_name,
  wr.hostname,
  wr.started_at,
  wr.last_heartbeat_at,
  wr.last_task_at,
  wr.tasks_completed,
  wr.tasks_failed,
  wr.current_task_id,
  EXTRACT(EPOCH FROM (NOW() - wr.last_heartbeat_at)) as seconds_since_heartbeat,
  CASE
    WHEN wr.status = 'offline' THEN 'offline'
    WHEN wr.last_heartbeat_at < NOW() - INTERVAL '2 minutes' THEN 'stale'
    WHEN wr.current_task_id IS NOT NULL THEN 'busy'
    ELSE 'ready'
  END as health_status
FROM worker_registry wr
WHERE wr.status != 'terminated'
ORDER BY wr.status = 'active' DESC, wr.last_heartbeat_at DESC;

COMMENT ON TABLE worker_registry IS 'Tracks all workers that have registered with the system';
COMMENT ON TABLE worker_name_pool IS 'Pool of friendly names for workers - expandable via API';