package service

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

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

// IvpdClient 阿里云 IVPD SegmentImage（服务端 AK，不暴露给客户端）
type IvpdClient struct {
	accessKeyID     string
	accessKeySecret string
	regionID        string
	client          *http.Client
}

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

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

// SegmentImageURL 调用 IVPD SegmentImage，返回结果图 HTTP URL
func (c *IvpdClient) SegmentImageURL(ctx context.Context, imageURL string) (string, error) {
	if !c.enabled() {
		return "", fmt.Errorf("IVPD 未配置 OSS AccessKey")
	}
	imageURL = strings.TrimSpace(imageURL)
	if !strings.HasPrefix(imageURL, "http://") && !strings.HasPrefix(imageURL, "https://") {
		return "", fmt.Errorf("IVPD 需要可访问的图片 URL")
	}

	params := map[string]string{
		"Format":           "JSON",
		"Version":          "2019-06-25",
		"AccessKeyId":      c.accessKeyID,
		"SignatureMethod":  "HMAC-SHA1",
		"Timestamp":        time.Now().UTC().Format("2006-01-02T15:04:05Z"),
		"SignatureVersion": "1.0",
		"SignatureNonce":   uuid.NewString(),
		"Action":           "SegmentImage",
		"RegionId":         c.regionID,
		"Url":              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("ivpd.%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 "", mapIvpdError(res.StatusCode, string(raw))
	}

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

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

	outURL := pickIvpdResultURL(data)
	if outURL == "" {
		return "", fmt.Errorf("IVPD 未返回结果图 URL")
	}
	return outURL, nil
}

func pickIvpdResultURL(data map[string]interface{}) string {
	if result, ok := data["Result"].(map[string]interface{}); ok {
		if u, ok := result["Url"].(string); ok && isHTTPURL(u) {
			return u
		}
		if u, ok := result["URL"].(string); ok && isHTTPURL(u) {
			return u
		}
	}
	if result, ok := data["result"].(map[string]interface{}); ok {
		if u, ok := result["url"].(string); ok && isHTTPURL(u) {
			return u
		}
	}
	if u, ok := data["Url"].(string); ok && isHTTPURL(u) {
		return u
	}
	return pickModelScopeImageURL(data)
}

func percentEncode(s string) string {
	escaped := url.QueryEscape(s)
	escaped = strings.ReplaceAll(escaped, "+", "%20")
	escaped = strings.ReplaceAll(escaped, "*", "%2A")
	escaped = strings.ReplaceAll(escaped, "%7E", "~")
	return escaped
}

func mapIvpdBizError(code, message string) error {
	if code == "NeedOpen" || strings.Contains(strings.ToLower(message), "please open service") {
		return fmt.Errorf("IVPD（智能视觉生产）尚未开通：请登录阿里云控制台搜索「智能视觉生产」或「视觉智能开放平台」，选择华东2（上海）开通后再试")
	}
	if message != "" {
		return fmt.Errorf("IVPD %s: %s", code, message)
	}
	return fmt.Errorf("IVPD 错误: %s", code)
}

func mapIvpdError(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 mapIvpdBizError(code, msg)
		}
	}
	return fmt.Errorf("IVPD HTTP %d: %s", httpCode, truncate(raw, 240))
}