package store

import (
	"context"
	"database/sql"
)

type Work struct {
	AbandonedMerges []string
	StartMerges     []ClaimedMerge
	FinalizeMerges  []FinalizingMerge
	StartDiscards   []string
	FinishDiscards  []string
}

func (s *Store) Coordinate(ctx context.Context) (Work, error) {
	work := Work{}
	err := s.write(ctx, func(tx *sql.Tx, emit emitFunc) error {
		var err error
		work.AbandonedMerges, err = abandonMerges(ctx, tx, emit)
		if err != nil {
			return err
		}
		err = claimHeldMerges(ctx, tx, emit)
		if err != nil {
			return err
		}
		work.StartMerges, err = startableMerges(ctx, tx)
		if err != nil {
			return err
		}
		work.FinalizeMerges, err = finalizingMerges(ctx, tx)
		if err != nil {
			return err
		}
		_, err = tx.ExecContext(ctx, `UPDATE tasks SET discard_state = 'closing'
			WHERE status = 'active' AND discard_state = 'running'
				AND NOT EXISTS (SELECT 1 FROM agent_sessions s WHERE s.id = tasks.discard_session AND s.state = 'running')`)
		if err != nil {
			return err
		}
		work.StartDiscards, err = queryIDs(ctx, tx, `SELECT id FROM tasks WHERE status = 'active' AND discard_state = 'held' AND NOT `+implementerRunning)
		if err != nil {
			return err
		}
		work.FinishDiscards, err = queryIDs(ctx, tx, `SELECT id FROM tasks WHERE status = 'active' AND discard_state = 'closing'`)
		return err
	})
	return work, err
}