package store

import (
	"context"
	"database/sql"
	"errors"

	"g.fc.run/misc/byre/internal/api"
)

const snapshotColumns = `id, task_id, agent_session_id, n, commit_sha, tree_sha, event_seq, trigger, created_at`

func (s *Store) CreateSnapshot(ctx context.Context, snap api.Snapshot, projectID string) error {
	return s.write(ctx, func(tx *sql.Tx, emit emitFunc) error {
		_, err := tx.ExecContext(ctx, `INSERT INTO snapshots (`+snapshotColumns+`) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)`,
			snap.Id, snap.TaskId, snap.AgentSessionId, snap.N, snap.CommitSha, snap.TreeSha, snap.EventSeq, string(snap.Trigger), formatTime(snap.CreatedAt))
		if err != nil {
			return err
		}
		return emit(api.Event{
			Kind:           "snapshot.created",
			ProjectId:      &projectID,
			TaskId:         &snap.TaskId,
			AgentSessionId: &snap.AgentSessionId,
			Actor:          "byre",
			Payload:        ToPayload(snap),
		})
	})
}

func (s *Store) ListSnapshots(ctx context.Context, taskID string) ([]api.Snapshot, error) {
	rows, err := s.db.QueryContext(ctx, `SELECT `+snapshotColumns+` FROM snapshots WHERE task_id = ? ORDER BY n`, taskID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	snaps := []api.Snapshot{}
	for rows.Next() {
		snap, err := scanSnapshot(rows)
		if err != nil {
			return nil, err
		}
		snaps = append(snaps, snap)
	}
	return snaps, rows.Err()
}

func (s *Store) LastSnapshot(ctx context.Context, taskID string) (api.Snapshot, error) {
	snap, err := scanSnapshot(s.db.QueryRowContext(ctx, `SELECT `+snapshotColumns+` FROM snapshots WHERE task_id = ? ORDER BY n DESC LIMIT 1`, taskID))
	if errors.Is(err, sql.ErrNoRows) {
		return snap, ErrNotFound
	}
	return snap, err
}

func (s *Store) LastTaskSeq(ctx context.Context, taskID string) (int64, error) {
	seq := int64(0)
	err := s.db.QueryRowContext(ctx, `SELECT COALESCE(MAX(seq), 0) FROM events WHERE task_id = ?`, taskID).Scan(&seq)
	return seq, err
}

func scanSnapshot(row scanner) (api.Snapshot, error) {
	snap := api.Snapshot{}
	trigger := ""
	createdAt := ""
	err := row.Scan(&snap.Id, &snap.TaskId, &snap.AgentSessionId, &snap.N, &snap.CommitSha, &snap.TreeSha, &snap.EventSeq, &trigger, &createdAt)
	if err != nil {
		return snap, err
	}
	snap.Trigger = api.SnapshotTrigger(trigger)
	snap.CreatedAt, err = parseTime(createdAt)
	return snap, err
}