package service

import (
	"context"
	"crypto/hmac"
	"crypto/sha1"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"sort"
	"strings"
	"time"

	"github.com/google/uuid"
	"github.com/topfans/backend/gateway/config"
)

// ImagesegClient 视觉智能开放平台 — 分割抠图（imageseg）
type ImagesegClient struct {
	accessKeyID     string
	accessKeySecret string
	regionID        string
	client          *http.Client
}

func NewImagesegClient(ossCfg config.OSSConfig) *ImagesegClient {
	region := strings.TrimSpace(ossCfg.Region)
	region = strings.TrimPrefix(region, "oss-")
	if region == "" {
		region = "cn-shanghai"
	}
	return &ImagesegClient{
		accessKeyID:     strings.TrimSpace(ossCfg.AccessKeyID),
		accessKeySecret: strings.TrimSpace(ossCfg.AccessKeySecret),
		regionID:        region,
		client:          &http.Client{Timeout: 120 * time.Second},
	}
}

func (c *ImagesegClient) enabled() bool {
	return c.accessKeyID != "" && c.accessKeySecret != "" && c.accessKeyID != "your-access-key-id"
}

// SegmentHDBodyURL 人体高清抠图，返回结果图 URL（对应控制台已开通的 SegmentHDBody）
func (c *ImagesegClient) SegmentHDBodyURL(ctx context.Context, imageURL string) (string, error) {
	return c.callPOP(ctx, "SegmentHDBody", imageURL)
}

// SegmentCommonImageURL 通用分割抠图（异形主体可备选）
func (c *ImagesegClient) SegmentCommonImageURL(ctx context.Context, imageURL string) (string, error) {
	return c.callPOP(ctx, "SegmentCommonImage", imageURL)
}

func (c *ImagesegClient) callPOP(ctx context.Context, action, imageURL string) (string, error) {
	if !c.enabled() {
		return "", fmt.Errorf("分割抠图未配置 OSS AccessKey")
	}
	imageURL = strings.TrimSpace(imageURL)
	if !strings.HasPrefix(imageURL, "http://") && !strings.HasPrefix(imageURL, "https://") {
		return "", fmt.Errorf("分割抠图需要可访问的图片 URL")
	}

	params := map[string]string{
		"Format":           "JSON",
		"Version":          "2019-12-30",
		"AccessKeyId":      c.accessKeyID,
		"SignatureMethod":  "HMAC-SHA1",
		"Timestamp":        time.Now().UTC().Format("2006-01-02T15:04:05Z"),
		"SignatureVersion": "1.0",
		"SignatureNonce":   uuid.NewString(),
		"Action":           action,
		"ImageURL":         imageURL,
	}

	keys := make([]string, 0, len(params))
	for k := range params {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	pairs := make([]string, 0, len(keys))
	for _, k := range keys {
		pairs = append(pairs, percentEncode(k)+"="+percentEncode(params[k]))
	}
	canonicalized := strings.Join(pairs, "&")
	stringToSign := "POST&" + percentEncode("/") + "&" + percentEncode(canonicalized)
	mac := hmac.New(sha1.New, []byte(c.accessKeySecret+"&"))
	mac.Write([]byte(stringToSign))
	signature := base64.StdEncoding.EncodeToString(mac.Sum(nil))
	body := canonicalized + "&Signature=" + percentEncode(signature)

	host := fmt.Sprintf("imageseg.%s.aliyuncs.com", c.regionID)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, "https://"+host+"/", strings.NewReader(body))
	if err != nil {
		return "", err
	}
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")

	res, err := c.client.Do(req)
	if err != nil {
		return "", err
	}
	defer res.Body.Close()

	raw, err := io.ReadAll(io.LimitReader(res.Body, 1<<20))
	if err != nil {
		return "", err
	}
	if res.StatusCode < 200 || res.StatusCode >= 300 {
		return "", mapImagesegHTTPError(res.StatusCode, string(raw))
	}

	var data map[string]interface{}
	if err := json.Unmarshal(raw, &data); err != nil {
		return "", fmt.Errorf("分割抠图返回非 JSON")
	}

	if code, ok := data["Code"]; ok {
		if s := fmt.Sprint(code); s != "" && s != "0" && !strings.EqualFold(s, "success") {
			msg, _ := data["Message"].(string)
			return "", mapImagesegBizError(s, msg)
		}
	}

	flat := data
	if inner, ok := data["Data"].(string); ok && inner != "" {
		var parsed map[string]interface{}
		if err := json.Unmarshal([]byte(inner), &parsed); err == nil {
			for k, v := range parsed {
				flat[k] = v
			}
		}
	}
	if inner, ok := data["Data"].(map[string]interface{}); ok {
		for k, v := range inner {
			flat[k] = v
		}
	}

	outURL := pickImagesegResultURL(flat)
	if outURL == "" {
		return "", fmt.Errorf("分割抠图未返回结果图 URL")
	}
	return outURL, nil
}

func pickImagesegResultURL(data map[string]interface{}) string {
	for _, key := range []string{"ImageURL", "imageURL", "Url", "url", "ResultImageURL"} {
		if u, ok := data[key].(string); ok && isHTTPURL(u) {
			return u
		}
	}
	return pickModelScopeImageURL(data)
}

func mapImagesegBizError(code, message string) error {
	lower := strings.ToLower(message)
	if code == "InvalidApi.NotPurchase" || strings.Contains(lower, "not purchase") || strings.Contains(lower, "notpurchase") {
		return fmt.Errorf("分割抠图能力未开通：请在视觉智能开放平台控制台确认 SegmentHDBody 已开通（华东2-上海）")
	}
	if code == "Forbidden" || strings.Contains(lower, "no permission") {
		return fmt.Errorf("分割抠图无权限：请为 RAM 用户添加 AliyunVIAPIFullAccess 策略")
	}
	if message != "" {
		return fmt.Errorf("分割抠图 %s: %s", code, message)
	}
	return fmt.Errorf("分割抠图错误: %s", code)
}

func mapImagesegHTTPError(httpCode int, raw string) error {
	var data map[string]interface{}
	if err := json.Unmarshal([]byte(raw), &data); err == nil {
		code := fmt.Sprint(data["Code"])
		msg, _ := data["Message"].(string)
		if code != "" && code != "<nil>" {
			return mapImagesegBizError(code, msg)
		}
	}
	return fmt.Errorf("分割抠图 HTTP %d: %s", httpCode, truncate(raw, 240))
}