// 资源对应的对象存储配置解析：系统存储、用户自有存储与历史位置。

package app

import (
	"errors"
	"strings"

	"gorm.io/gorm"
	"infinite-canvas/backend/internal/model"
)

func (s *Service) activeOSSSetting() (ossSettingValue, error) {
	_, setting, err := s.readOSSSetting()
	if err != nil {
		return ossSettingValue{}, err
	}
	return validateActiveOSSSetting(setting, "管理员尚未启用 OSS", "平台 OSS 配置不完整，请联系管理员")
}

func (s *Service) activeResourceOSSSetting(userID string) (ossSettingValue, string, bool, error) {
	userSetting, value, err := s.readUserOSSSetting(userID)
	if err != nil {
		return ossSettingValue{}, "", false, err
	}
	_, systemValue, err := s.readOSSSetting()
	if err != nil {
		return ossSettingValue{}, "", false, err
	}
	userAllowed := value.Provider != s3Provider || systemValue.AllowUserS3
	if userSetting != nil && value.Enabled && userAllowed {
		value, err = validateActiveOSSSetting(value, "用户 OSS 尚未启用", "你的 OSS 配置不完整")
		return value, firstNonEmpty(value.StorageLocationID, userSetting.ID), true, err
	}
	if !systemValue.Enabled {
		return ossSettingValue{}, "", false, nil
	}
	systemValue, err = validateActiveOSSSetting(systemValue, "管理员尚未启用 OSS", "平台 OSS 配置不完整，请联系管理员")
	return systemValue, systemValue.StorageLocationID, true, err
}

func (s *Service) ossSettingForResource(userID string, resource *model.Resource) (ossSettingValue, error) {
	var setting ossSettingValue
	var err error
	if resource.StorageSettingID != "" {
		_, setting, err = s.storageLocationValue(resource.StorageSettingID)
		if errors.Is(err, gorm.ErrRecordNotFound) {
			_, setting, err = s.readUserOSSSettingByID(userID, resource.StorageSettingID)
		}
		if err == nil {
			_, current, currentErr := s.readUserOSSSetting(userID)
			if currentErr != nil {
				return ossSettingValue{}, currentErr
			}
			// 密钥固定在资源绑定的历史版本；只有存储位置完全一致时，才允许沿用当前 CDN。
			if resourceStorageMatches(current, resource) {
				setting.CDNBaseURL = current.CDNBaseURL
				// CDN 的鉴权方式和回退策略属于分发配置，而不是资源创建时的
				// 凭据。存储位置未变时沿用当前策略，避免历史资源因管理员
				// 刚补齐 CDN 鉴权配置而继续回源。
				setting.Delivery = current.Delivery
			}
		}
	} else {
		// 早期资源没有 StorageSettingID，但资源本身仍记录了 provider/endpoint/bucket。
		// 先从用户 OSS 历史版本中按存储位置反查，不能把当前七牛配置猜给历史阿里云对象。
		setting, err = s.userOSSSettingForResource(userID, resource)
		if errors.Is(err, gorm.ErrRecordNotFound) {
			_, setting, err = s.readOSSSetting()
		}
	}
	if err != nil {
		return ossSettingValue{}, err
	}
	resourceProvider := strings.ToLower(strings.TrimSpace(resource.Provider))
	resourceMatchesSetting := resourceStorageMatches(setting, resource)
	setting, err = ossSettingForProvider(setting, firstNonEmpty(resource.Provider, setting.Provider))
	if err != nil {
		return ossSettingValue{}, err
	}
	setting.Endpoint = firstNonEmpty(resource.Endpoint, setting.Endpoint)
	setting.Bucket = firstNonEmpty(resource.Bucket, setting.Bucket)
	// CDN 是具体存储位置的出口，不得在 provider/endpoint/bucket 不匹配时继续沿用，
	// 否则切换到七牛后会把历史阿里云 objectKey 拼成七牛域名。
	if !resourceMatchesSetting || (resourceProvider != "" && resourceProvider != setting.Provider) {
		setting.CDNBaseURL = ""
	}
	if setting.AccessKeyID == "" || setting.AccessKeySecret == "" {
		return ossSettingValue{}, errors.New("对象存储访问密钥不可用")
	}
	return setting, nil
}

func (s *Service) userOSSSettingForResource(userID string, resource *model.Resource) (ossSettingValue, error) {
	settings, err := s.repo.UserOSSSettingsForUser(userID)
	if err != nil {
		return ossSettingValue{}, err
	}
	for index := range settings {
		value, valueErr := s.userOSSSettingValue(&settings[index])
		if valueErr != nil {
			return ossSettingValue{}, valueErr
		}
		if resourceStorageMatches(value, resource) {
			return value, nil
		}
	}
	return ossSettingValue{}, gorm.ErrRecordNotFound
}

func resourceStorageMatches(setting ossSettingValue, resource *model.Resource) bool {
	if resource == nil {
		return false
	}
	setting = normalizeOSSSetting(setting)
	return setting.Provider == strings.ToLower(strings.TrimSpace(resource.Provider)) &&
		setting.Endpoint == strings.TrimRight(strings.TrimSpace(resource.Endpoint), "/") &&
		setting.Bucket == strings.TrimSpace(resource.Bucket)
}

func ossSettingForProvider(setting ossSettingValue, provider string) (ossSettingValue, error) {
	setting = normalizeOSSSetting(setting)
	provider = strings.ToLower(strings.TrimSpace(provider))
	if provider == "" || provider == setting.Provider {
		return setting, nil
	}
	credentials, ok := setting.ArchivedCredentials[provider]
	if !ok || credentials.AccessKeyID == "" || credentials.AccessKeySecret == "" {
		return ossSettingValue{}, errors.New("历史对象存储访问密钥不可用")
	}
	setting.Provider = provider
	setting.AccessKeyID = credentials.AccessKeyID
	setting.AccessKeySecret = credentials.AccessKeySecret
	return setting, nil
}

func validateActiveOSSSetting(setting ossSettingValue, disabledMessage string, incompleteMessage string) (ossSettingValue, error) {
	setting = normalizeOSSSetting(setting)
	if !setting.Enabled {
		return ossSettingValue{}, BadAuthRequest(disabledMessage)
	}
	if setting.Provider != aliyunOSSProvider && setting.Provider != tencentCOSProvider && setting.Provider != qiniuKodoProvider && setting.Provider != s3Provider {
		return ossSettingValue{}, BadAuthRequest("仅支持阿里云 OSS、腾讯云 COS、七牛云 Kodo 和通用 S3")
	}
	if setting.Bucket == "" || setting.Endpoint == "" || setting.AccessKeyID == "" || setting.AccessKeySecret == "" {
		return ossSettingValue{}, BadAuthRequest(incompleteMessage)
	}
	return setting, nil
}