-- Processing Jobs Table
-- This table stores document processing jobs that need to be executed
-- Replaces the in-memory job queue with persistent database storage

CREATE TABLE IF NOT EXISTS processing_jobs (
  -- Primary key
  id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),

  -- Job data
  document_id UUID NOT NULL REFERENCES documents(id) ON DELETE CASCADE,
  user_id TEXT NOT NULL,

  -- Job status and progress
  status TEXT NOT NULL CHECK (status IN ('pending', 'processing', 'completed', 'failed', 'retrying')),
  attempts INTEGER NOT NULL DEFAULT 0,
  max_attempts INTEGER NOT NULL DEFAULT 3,

  -- Processing options (stored as JSONB)
  options JSONB,

  -- Timestamps
  created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT NOW(),
  started_at TIMESTAMP WITH TIME ZONE,
  completed_at TIMESTAMP WITH TIME ZONE,
  updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),

  -- Error tracking
  error TEXT,
  last_error_at TIMESTAMP WITH TIME ZONE,

  -- Result storage
  result JSONB
);

-- Indexes for efficient querying
CREATE INDEX IF NOT EXISTS idx_processing_jobs_status ON processing_jobs(status);
CREATE INDEX IF NOT EXISTS idx_processing_jobs_created_at ON processing_jobs(created_at);
CREATE INDEX IF NOT EXISTS idx_processing_jobs_document_id ON processing_jobs(document_id);
CREATE INDEX IF NOT EXISTS idx_processing_jobs_user_id ON processing_jobs(user_id);
CREATE INDEX IF NOT EXISTS idx_processing_jobs_pending ON processing_jobs(status, created_at) WHERE status = 'pending';

-- Function to automatically update updated_at timestamp
CREATE OR REPLACE FUNCTION update_processing_jobs_updated_at()
RETURNS TRIGGER AS $$
BEGIN
  NEW.updated_at = NOW();
  RETURN NEW;
END;
$$ LANGUAGE plpgsql;

-- Trigger to call the update function
DROP TRIGGER IF EXISTS set_processing_jobs_updated_at ON processing_jobs;
CREATE TRIGGER set_processing_jobs_updated_at
  BEFORE UPDATE ON processing_jobs
  FOR EACH ROW
  EXECUTE FUNCTION update_processing_jobs_updated_at();

-- Grant permissions (adjust role name as needed)
-- ALTER TABLE processing_jobs ENABLE ROW LEVEL SECURITY;

-- Optional: Create a view for monitoring
CREATE OR REPLACE VIEW processing_jobs_summary AS
SELECT
  status,
  COUNT(*) as count,
  AVG(EXTRACT(EPOCH FROM (COALESCE(completed_at, NOW()) - created_at))) as avg_duration_seconds,
  MAX(created_at) as latest_created_at
FROM processing_jobs
GROUP BY status;

-- Comments for documentation
COMMENT ON TABLE processing_jobs IS 'Stores document processing jobs for async background processing';
COMMENT ON COLUMN processing_jobs.status IS 'Current status: pending, processing, completed, failed, retrying';
COMMENT ON COLUMN processing_jobs.attempts IS 'Number of processing attempts made';
COMMENT ON COLUMN processing_jobs.max_attempts IS 'Maximum number of retry attempts allowed';
COMMENT ON COLUMN processing_jobs.options IS 'Processing options and configuration (JSON)';
COMMENT ON COLUMN processing_jobs.error IS 'Last error message if processing failed';