package store

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

	"github.com/rvbox/rvbox/internal/domain"
)

var ErrDispatchMismatch = errors.New("command acceptance does not match dispatched generation or revision")

// RecordCommandAcceptance fences an acknowledgement to the exact dispatch that
// produced it. Repeated acknowledgements are harmless; a stale session cannot
// advance a newer dispatch or overwrite a terminal decision.
func (store *Store) RecordCommandAcceptance(ctx context.Context, issueUUID domain.UUID, clientID string, generation, revision uint64, accepted bool, now time.Time) (bool, error) {
	if isZeroUUID([16]byte(issueUUID)) || clientID == "" || generation == 0 || revision == 0 || now.IsZero() {
		return false, ErrDispatchMismatch
	}
	store.writeMu.Lock()
	defer store.writeMu.Unlock()
	database, err := store.openDatabase()
	if err != nil {
		return false, err
	}
	targetLifecycle := 3
	if !accepted {
		targetLifecycle = 11
	}
	query := `UPDATE commands SET lifecycle = ?`
	args := []any{targetLifecycle}
	if !accepted {
		query += `, terminal_time = ?`
		args = append(args, now.UTC().UnixNano())
	}
	query += ` WHERE issue_uuid = ? AND client_id = ? AND lifecycle = 2 AND target_session_generation = ? AND revision = ?`
	args = append(args, issueUUID[:], clientID, generation, revision)
	result, err := database.ExecContext(ctx, query, args...)
	if err != nil {
		return false, err
	}
	changed, err := result.RowsAffected()
	if err != nil {
		return false, err
	}
	if changed == 1 {
		return true, nil
	}
	var lifecycle uint32
	var storedGeneration, storedRevision uint64
	err = database.QueryRowContext(ctx, `SELECT lifecycle, COALESCE(target_session_generation, 0), revision FROM commands WHERE issue_uuid = ? AND client_id = ?`, issueUUID[:], clientID).Scan(&lifecycle, &storedGeneration, &storedRevision)
	if errors.Is(err, sql.ErrNoRows) {
		return false, ErrDispatchMismatch
	}
	if err != nil {
		return false, err
	}
	if storedGeneration == generation && storedRevision == revision && ((accepted && (lifecycle == 3 || lifecycle == 4)) || (!accepted && lifecycle == 11)) {
		return false, nil
	}
	return false, ErrDispatchMismatch
}