package repository

import (
	"context"
	"encoding/json"
	"fmt"
	"permission/reborn/config"
	"permission/reborn/domain/errors"
	"permission/reborn/domain/repository"
	"time"

	"github.com/redis/go-redis/v9"
)

type cacheRepository struct {
	client *redis.Client
	config config.RedisConfig
}

// NewCacheRepository 建立快取 Repository
func NewCacheRepository(client *redis.Client, cfg config.RedisConfig) repository.CacheRepository {
	return &cacheRepository{
		client: client,
		config: cfg,
	}
}

func (r *cacheRepository) Get(ctx context.Context, key string) (string, error) {
	val, err := r.client.Get(ctx, key).Result()
	if err != nil {
		if err == redis.Nil {
			return "", errors.ErrNotFound
		}
		return "", errors.Wrap(errors.ErrCodeCacheError, "failed to get cache", err)
	}
	return val, nil
}

func (r *cacheRepository) Set(ctx context.Context, key, value string, ttl time.Duration) error {
	if ttl == 0 {
		ttl = r.getDefaultTTL(key)
	}

	err := r.client.Set(ctx, key, value, ttl).Err()
	if err != nil {
		return errors.Wrap(errors.ErrCodeCacheError, "failed to set cache", err)
	}
	return nil
}

func (r *cacheRepository) Delete(ctx context.Context, keys ...string) error {
	if len(keys) == 0 {
		return nil
	}

	err := r.client.Del(ctx, keys...).Err()
	if err != nil {
		return errors.Wrap(errors.ErrCodeCacheError, "failed to delete cache", err)
	}
	return nil
}

func (r *cacheRepository) Exists(ctx context.Context, key string) (bool, error) {
	count, err := r.client.Exists(ctx, key).Result()
	if err != nil {
		return false, errors.Wrap(errors.ErrCodeCacheError, "failed to check cache exists", err)
	}
	return count > 0, nil
}

func (r *cacheRepository) GetObject(ctx context.Context, key string, dest interface{}) error {
	val, err := r.Get(ctx, key)
	if err != nil {
		return err
	}

	if err := json.Unmarshal([]byte(val), dest); err != nil {
		return errors.Wrap(errors.ErrCodeCacheError, "failed to unmarshal cache object", err)
	}

	return nil
}

func (r *cacheRepository) SetObject(ctx context.Context, key string, value interface{}, ttl time.Duration) error {
	data, err := json.Marshal(value)
	if err != nil {
		return errors.Wrap(errors.ErrCodeCacheError, "failed to marshal cache object", err)
	}

	return r.Set(ctx, key, string(data), ttl)
}

func (r *cacheRepository) DeletePattern(ctx context.Context, pattern string) error {
	var cursor uint64
	var keys []string

	for {
		var scanKeys []string
		var err error

		scanKeys, cursor, err = r.client.Scan(ctx, cursor, pattern, 100).Result()
		if err != nil {
			return errors.Wrap(errors.ErrCodeCacheError, "failed to scan cache keys", err)
		}

		keys = append(keys, scanKeys...)

		if cursor == 0 {
			break
		}
	}

	if len(keys) > 0 {
		return r.Delete(ctx, keys...)
	}

	return nil
}

// getDefaultTTL 根據 key 類型取得預設 TTL
func (r *cacheRepository) getDefaultTTL(key string) time.Duration {
	switch {
	case key == repository.CacheKeyPermissionTree:
		return r.config.PermissionTreeTTL
	case key == repository.CacheKeyPermissionList:
		return r.config.PermissionTreeTTL
	case isUserPermissionKey(key):
		return r.config.UserPermissionTTL
	case isRolePermissionKey(key):
		return r.config.RolePolicyTTL
	default:
		return 5 * time.Minute
	}
}

func isUserPermissionKey(key string) bool {
	return len(key) > len(repository.CacheKeyUserPermissionPrefix) &&
		key[:len(repository.CacheKeyUserPermissionPrefix)] == repository.CacheKeyUserPermissionPrefix
}

func isRolePermissionKey(key string) bool {
	return len(key) > len(repository.CacheKeyRolePermissionPrefix) &&
		key[:len(repository.CacheKeyRolePermissionPrefix)] == repository.CacheKeyRolePermissionPrefix
}

// InvalidateUserPermission 清除使用者權限快取
func (r *cacheRepository) InvalidateUserPermission(ctx context.Context, uid string) error {
	key := fmt.Sprintf("%s%s", repository.CacheKeyUserPermissionPrefix, uid)
	return r.Delete(ctx, key)
}

// InvalidateRolePermission 清除角色權限快取
func (r *cacheRepository) InvalidateRolePermission(ctx context.Context, roleUID string) error {
	key := fmt.Sprintf("%s%s", repository.CacheKeyRolePermissionPrefix, roleUID)
	return r.Delete(ctx, key)
}

// InvalidateAllPermissions 清除所有權限相關快取
func (r *cacheRepository) InvalidateAllPermissions(ctx context.Context) error {
	patterns := []string{
		repository.CacheKeyPermissionTree,
		repository.CacheKeyPermissionList,
		repository.CacheKeyUserPermissionPrefix + "*",
		repository.CacheKeyRolePermissionPrefix + "*",
	}

	for _, pattern := range patterns {
		if err := r.DeletePattern(ctx, pattern); err != nil {
			return err
		}
	}

	return nil
}