package authgate

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

	"atcr.io/pkg/atproto"
)

// holdResolver resolves a user's default hold DID, preferring the
// Jetstream-cached `users.default_hold_did` and falling back to the
// AppView's configured default. Embedded into types in this package
// (Authorizer, ServiceAuthFetcher) so they share one implementation.
type holdResolver struct {
	db             *sql.DB
	defaultHoldDID string
}

// resolveHoldDID returns the normalized hold DID for userDID, or "" if no
// hold is configured anywhere (caller decides how to degrade).
func (h *holdResolver) resolveHoldDID(ctx context.Context, userDID string) (string, error) {
	var cached sql.NullString
	err := h.db.QueryRowContext(ctx,
		"SELECT default_hold_did FROM users WHERE did = ?", userDID,
	).Scan(&cached)
	if err != nil && !errors.Is(err, sql.ErrNoRows) {
		return "", fmt.Errorf("look up default hold: %w", err)
	}

	holdDID := ""
	if cached.Valid {
		holdDID = cached.String
	}
	if holdDID == "" {
		holdDID = h.defaultHoldDID
	}
	if holdDID == "" {
		return "", nil
	}

	resolved, err := atproto.ResolveHoldDID(ctx, holdDID)
	if err != nil {
		return "", fmt.Errorf("resolve hold DID %s: %w", holdDID, err)
	}
	return resolved, nil
}