// 生成结果（data URL / 远程地址）的持久化与远程下载。
//
// 远程下载经过出站地址校验（validateRemoteResourceURL），防止 SSRF。

package app

import (
	"bytes"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"image"
	"io"
	"mime"
	"net/http"
	"net/url"
	"path"
	"path/filepath"
	"strings"
	"time"
)

func localObjectKey(userID string, kind string, fileName string, mimeType string, now time.Time) string {
	ext := resourceFileExtension(fileName, mimeType, kind)
	return path.Join("users", safeObjectSegment(userID), kind, now.Format("2006/01/02"), newID()+ext)
}

func (s *Service) persistGeneratedMediaResult(userID string, result map[string]interface{}) (map[string]interface{}, error) {
	return s.persistGeneratedMediaResultMode(userID, result, false, true)
}

func (s *Service) persistLegacyGeneratedMediaResult(userID string, result map[string]interface{}) (map[string]interface{}, error) {
	return s.persistGeneratedMediaResultMode(userID, result, true, false)
}

func (s *Service) persistGeneratedMediaResultMode(userID string, result map[string]interface{}, skipInvalidDataURL bool, enforceQuota bool) (map[string]interface{}, error) {
	if result == nil {
		return map[string]interface{}{}, nil
	}
	encoded, err := json.Marshal(result)
	if err != nil {
		return nil, err
	}
	var normalized map[string]interface{}
	if err := json.Unmarshal(encoded, &normalized); err != nil {
		return nil, err
	}
	value, err := s.persistGeneratedMediaValueMode(userID, normalized, skipInvalidDataURL, enforceQuota)
	if err != nil {
		return nil, err
	}
	return value.(map[string]interface{}), nil
}

func (s *Service) persistGeneratedMediaValue(userID string, value interface{}) (interface{}, error) {
	return s.persistGeneratedMediaValueMode(userID, value, false, true)
}

func (s *Service) persistGeneratedMediaValueMode(userID string, value interface{}, skipInvalidDataURL bool, enforceQuota bool) (interface{}, error) {
	switch item := value.(type) {
	case []interface{}:
		for index, child := range item {
			stored, err := s.persistGeneratedMediaValueMode(userID, child, skipInvalidDataURL, enforceQuota)
			if err != nil {
				return nil, err
			}
			item[index] = stored
		}
		return item, nil
	case map[string]interface{}:
		if raw := inlineMediaValue(item); raw != "" {
			mimeType, data, err := s.decodeDataURL(raw)
			if err != nil && !skipInvalidDataURL {
				return nil, err
			}
			if err == nil {
				kind := normalizeResourceKind("", mimeType)
				width, height := intValue(item["width"]), intValue(item["height"])
				if kind == "image" && (width <= 0 || height <= 0) {
					width, height = imageDimensions(data)
				}
				quotaDay := ""
				if enforceQuota {
					quotaDay, err = s.reserveGeneratedResourceQuota(userID, int64(len(data)))
					if err != nil {
						return nil, err
					}
				}
				resource, _, err := s.storeResource(userID, kind, "generated."+extensionFromMimeType(mimeType), mimeType, int64(len(data)), width, height, int64(intValue(item["durationMs"])), bytes.NewReader(data), nil, false)
				if err != nil {
					if enforceQuota {
						s.releaseUserUploadQuota(userID, quotaDay, int64(len(data)))
					}
					return nil, fmt.Errorf("生成内容写入资源存储失败：%w", err)
				}
				if enforceQuota {
					s.commitUserUploadQuota(userID, int64(len(data)))
				}
				resourceURL := resourceFileURL(resource.ID)
				for _, key := range []string{"dataUrl", "content", "url", "coverUrl"} {
					if text, ok := item[key].(string); ok && (text == raw || strings.HasPrefix(text, "blob:")) {
						item[key] = resourceURL
					}
				}
				if _, ok := item["dataUrl"]; ok {
					item["dataUrl"] = resourceURL
				}
				item["url"] = resourceURL
				item["storageKey"] = "resource:" + resource.ID
				item["resourceId"] = resource.ID
				item["bytes"] = resource.Size
				item["mimeType"] = resource.MimeType
				item["width"] = resource.Width
				item["height"] = resource.Height
			}
		}
		for key, child := range item {
			stored, err := s.persistGeneratedMediaValueMode(userID, child, skipInvalidDataURL, enforceQuota)
			if err != nil {
				return nil, err
			}
			item[key] = stored
		}
		return item, nil
	default:
		return value, nil
	}
}

func inlineMediaValue(item map[string]interface{}) string {
	for _, key := range []string{"dataUrl", "content", "url", "coverUrl"} {
		if text, ok := item[key].(string); ok && (strings.HasPrefix(text, "data:image/") || strings.HasPrefix(text, "data:video/") || strings.HasPrefix(text, "data:audio/")) {
			return text
		}
	}
	return ""
}

func (s *Service) decodeDataURL(value string) (string, []byte, error) {
	header, encoded, ok := strings.Cut(value, ",")
	if !ok || !strings.HasPrefix(header, "data:") || !strings.HasSuffix(strings.ToLower(header), ";base64") {
		return "", nil, fmt.Errorf("%w：格式无效", errInvalidGeneratedDataURL)
	}
	mimeType := strings.TrimSuffix(strings.TrimPrefix(header, "data:"), ";base64")
	data, err := base64.StdEncoding.DecodeString(encoded)
	if err != nil {
		return "", nil, fmt.Errorf("%w：base64 解码失败：%v", errInvalidGeneratedDataURL, err)
	}
	policy, err := s.RuntimePolicy()
	if err != nil {
		return "", nil, err
	}
	if int64(len(data)) > megabytes(policy.Resource.GeneratedFileMB) {
		return "", nil, fmt.Errorf("单个生成资源超过 %dMB", policy.Resource.GeneratedFileMB)
	}
	return mimeType, data, nil
}

func intValue(value interface{}) int {
	switch number := value.(type) {
	case float64:
		return int(number)
	case int:
		return number
	case int64:
		return int(number)
	default:
		return 0
	}
}

type remoteResourcePayload struct {
	url      string
	endpoint string
	fileName string
	mimeType string
	data     []byte
}

func downloadRemoteResource(rawURL string, maxBytes int64) (remoteResourcePayload, error) {
	parsed, err := validateRemoteResourceURL(rawURL)
	if err != nil {
		return remoteResourcePayload{}, err
	}
	client := OutboundHTTPClient(90 * time.Second)
	req, err := http.NewRequest(http.MethodGet, parsed.String(), nil)
	if err != nil {
		return remoteResourcePayload{}, err
	}
	resp, err := client.Do(req)
	if err != nil {
		return remoteResourcePayload{}, err
	}
	defer resp.Body.Close()
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return remoteResourcePayload{}, fmt.Errorf("远程资源下载失败：%s", resp.Status)
	}
	data, err := io.ReadAll(io.LimitReader(resp.Body, maxBytes))
	if err != nil {
		return remoteResourcePayload{}, err
	}
	if int64(len(data)) >= maxBytes {
		return remoteResourcePayload{}, BadAuthRequest(fmt.Sprintf("远程资源必须小于 %s", formatStorageLimit(maxBytes)))
	}
	mimeType := strings.TrimSpace(resp.Header.Get("Content-Type"))
	if idx := strings.Index(mimeType, ";"); idx >= 0 {
		mimeType = strings.TrimSpace(mimeType[:idx])
	}
	if mimeType == "" || mimeType == "application/octet-stream" {
		mimeType = http.DetectContentType(data)
	}
	fileName := path.Base(parsed.Path)
	if fileName == "" || fileName == "." || !strings.Contains(fileName, ".") {
		fileName = "resource." + extensionFromMimeType(mimeType)
	}
	return remoteResourcePayload{url: parsed.String(), endpoint: parsed.Host, fileName: fileName, mimeType: mimeType, data: data}, nil
}

func openRemoteResource(rawURL string) (io.ReadCloser, error) {
	parsed, err := validateRemoteResourceURL(rawURL)
	if err != nil {
		return nil, err
	}
	client := OutboundHTTPClient(90 * time.Second)
	resp, err := client.Get(parsed.String())
	if err != nil {
		return nil, err
	}
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		defer resp.Body.Close()
		return nil, fmt.Errorf("远程资源读取失败：%s", resp.Status)
	}
	return resp.Body, nil
}

func validateRemoteResourceURL(rawURL string) (*url.URL, error) {
	return ValidateOutboundURL(rawURL)
}

func extensionFromMimeType(mimeType string) string {
	if strings.Contains(mimeType, "png") {
		return "png"
	}
	if strings.Contains(mimeType, "jpeg") {
		return "jpg"
	}
	if strings.Contains(mimeType, "webp") {
		return "webp"
	}
	if strings.Contains(mimeType, "gif") {
		return "gif"
	}
	if strings.Contains(mimeType, "mp4") {
		return "mp4"
	}
	if strings.Contains(mimeType, "webm") {
		return "webm"
	}
	if strings.Contains(mimeType, "mpeg") {
		return "mp3"
	}
	if strings.Contains(mimeType, "wav") {
		return "wav"
	}
	return "bin"
}

func resourceFileExtension(fileName string, mimeType string, kind string) string {
	if ext := strings.ToLower(filepath.Ext(strings.TrimSpace(fileName))); ext != "" && ext != "." {
		return ext
	}
	cleanMimeType := strings.TrimSpace(strings.Split(mimeType, ";")[0])
	if extensions, err := mime.ExtensionsByType(cleanMimeType); err == nil && len(extensions) > 0 {
		return strings.ToLower(extensions[0])
	}
	switch kind {
	case "image":
		return ".png"
	case "video":
		return ".mp4"
	case "audio":
		return ".mp3"
	default:
		return ".bin"
	}
}

func imageDimensions(data []byte) (int, int) {
	config, _, err := image.DecodeConfig(bytes.NewReader(data))
	if err != nil {
		return 0, 0
	}
	return config.Width, config.Height
}