// Package service provides business logic / use cases for the application.
package service

import (
	"context"
	"fmt"

	"git.threesix.ai/jordan/slate-test-1770505673/pkg/logging"
	"git.threesix.ai/jordan/slate-test-1770505673/services/preferences-api/internal/domain"
	"git.threesix.ai/jordan/slate-test-1770505673/services/preferences-api/internal/port"
)

// PreferenceService handles preference-related business logic.
type PreferenceService struct {
	repo   port.PreferenceRepository
	logger *logging.Logger
}

// NewPreferenceService creates a new preference service.
func NewPreferenceService(repo port.PreferenceRepository, logger *logging.Logger) *PreferenceService {
	return &PreferenceService{
		repo:   repo,
		logger: logger.WithService("PreferenceService"),
	}
}

// Get returns all preferences for a user.
func (s *PreferenceService) Get(ctx context.Context, userID string) (map[string]string, error) {
	return s.repo.GetByUserID(ctx, userID)
}

// Upsert validates and persists preferences, then returns the full preference set.
func (s *PreferenceService) Upsert(ctx context.Context, userID string, prefs map[string]string) (map[string]string, error) {
	// Validate all keys and values before persisting
	for key, value := range prefs {
		if err := domain.ValidateKey(key); err != nil {
			return nil, fmt.Errorf("%w", err)
		}
		if err := domain.ValidateValue(key, value); err != nil {
			return nil, fmt.Errorf("%w", err)
		}
	}

	if err := s.repo.Upsert(ctx, userID, prefs); err != nil {
		return nil, err
	}

	s.logger.Info("preferences updated", "user_id", userID, "keys_updated", len(prefs))

	// Return the full preference set after update
	return s.repo.GetByUserID(ctx, userID)
}