package qiniu

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

	"u-desk/internal/oss"
)

// Config 七牛云配置
type Config struct {
	AccessKey     string // 访问密钥
	SecretKey     string // 秘钥
	Bucket        string // 存储空间名称
	Region        string // 区域 z0=华东, z2=华南, as0=亚太0区
	UseHTTPS      bool   // 是否使用 HTTPS
	DownloadDomain string // 缓存的下载域名（由 resolveDownloadDomain 自动设置）
}

// Client 七牛云客户端
type Client struct {
	config     *Config
	httpClient *http.Client
	rsAPI      string // 资源管理 API
	rsfAPI     string // 资源列举 API (RSF)
	apiAPI     string // API 服务
}

// NewClient 创建七牛云客户端
func NewClient(config *Config) (*Client, error) {
	if config == nil {
		return nil, oss.NewError("INVALID_CONFIG", "config cannot be nil", nil)
	}
	if config.AccessKey == "" || config.SecretKey == "" {
		return nil, oss.NewError("INVALID_CONFIG", "access key and secret key are required", nil)
	}
	if config.Bucket == "" {
		return nil, oss.NewError("INVALID_CONFIG", "bucket name is required", nil)
	}

	// 设置默认区域
	if config.Region == "" {
		config.Region = "z0" // 华东
	}

	return &Client{
		config:     config,
		httpClient: &http.Client{Timeout: 30 * time.Second},
		rsAPI:      "http://rs.qiniu.com",
		rsfAPI:     "http://rsf.qbox.me", // 资源列举 API
		apiAPI:     "http://api.qiniu.com",
	}, nil
}

// generateAuthToken 生成管理认证 Token
func (c *Client) generateAuthToken(method, path, host, contentType string, body []byte) string {
	return c.generateAuthTokenWithQuery(method, path, "", host, contentType, body)
}

// generateAuthTokenWithQuery 生成管理认证 Token（支持 query string）
// https://developer.qiniu.com/kodo/1201/access-token
func (c *Client) generateAuthTokenWithQuery(method, path, query, host, contentType string, body []byte) string {
	var signingStr string

	signingStr = method + " " + path
	if query != "" {
		signingStr += "?" + query
	}
	signingStr += "\nHost: " + host
	if contentType != "" {
		signingStr += "\nContent-Type: " + contentType
	}
	signingStr += "\n\n"
	if contentType != "" && contentType != "application/octet-stream" && len(body) > 0 {
		signingStr += string(body)
	}

	h := hmac.New(sha1.New, []byte(c.config.SecretKey))
	h.Write([]byte(signingStr))
	signature := base64.URLEncoding.EncodeToString(h.Sum(nil))

	return "Qiniu " + c.config.AccessKey + ":" + signature
}

// encodeEntry 编码 EntryURI (bucket:key)
func (c *Client) encodeEntry(key string) string {
	entry := c.config.Bucket + ":" + key
	return base64.URLEncoding.EncodeToString([]byte(entry))
}

// getUploadDomain 获取上传域名
func (c *Client) getUploadDomain() string {
	if c.config.DownloadDomain != "" {
		if c.config.UseHTTPS {
			return "https://" + c.config.DownloadDomain
		}
		return "http://" + c.config.DownloadDomain
	}

	// 根据区域选择默认上传域名
	// 七牛云上传域名格式: up-<region>.qiniup.com 或 upload-<region>.qbox.me
	scheme := "https://"
	if !c.config.UseHTTPS {
		scheme = "http://"
	}

	// 根据区域返回上传域名
	switch c.config.Region {
	case "z0": // 华东
		return scheme + "up-z0.qiniup.com"
	case "z1": // 华北
		return scheme + "up-z1.qiniup.com"
	case "z2": // 华南
		return scheme + "up-z2.qiniup.com"
	case "na0": // 北美
		return scheme + "up-na0.qiniup.com"
	case "as0": // 亚太
		return scheme + "up-as0.qiniup.com"
	default:
		// 默认使用华东
		return scheme + "up-z0.qiniup.com"
	}
}

// doRequest 执行 HTTP 请求
func (c *Client) doRequest(method, path string, body io.Reader) (*http.Response, error) {
	url := c.rsAPI + path

	// 解析 path 和 query string
	signPath := path
	queryString := ""
	if idx := strings.Index(path, "?"); idx > 0 {
		signPath = path[:idx]
		queryString = path[idx+1:] // 去掉问号
	}

	// 读取 body 用于签名
	var bodyBytes []byte
	var err error
	if body != nil {
		bodyBytes, err = io.ReadAll(body)
		if err != nil {
			return nil, oss.NewError("REQUEST_ERROR", "failed to read request body", err)
		}
	}

	req, err := http.NewRequest(method, url, bytes.NewReader(bodyBytes))
	if err != nil {
		return nil, oss.NewError("REQUEST_ERROR", "failed to create request", err)
	}

	// 设置 Content-Type
	contentType := ""
	if method == "POST" || method == "PUT" {
		contentType = "application/x-www-form-urlencoded"
		req.Header.Set("Content-Type", contentType)
	}

	// 设置管理认证头（使用新的签名算法，包含 query string）
	host := "rs.qiniu.com"
	authToken := c.generateAuthTokenWithQuery(method, signPath, queryString, host, contentType, bodyBytes)
	req.Header.Set("Authorization", authToken)

	return c.httpClient.Do(req)
}

// doRSFRequest 执行 RSF (资源列举) API 请求
// RSF API 使用不同的 host (rsf.qbox.me)
func (c *Client) doRSFRequest(method, path string) (*http.Response, error) {
	url := c.rsfAPI + path

	// 解析 path 和 query string
	signPath := path
	queryString := ""
	if idx := strings.Index(path, "?"); idx > 0 {
		signPath = path[:idx]
		queryString = path[idx+1:] // 去掉问号
	}

	req, err := http.NewRequest(method, url, nil)
	if err != nil {
		return nil, oss.NewError("REQUEST_ERROR", "failed to create request", err)
	}

	// 设置 Content-Type
	contentType := "application/x-www-form-urlencoded"
	req.Header.Set("Content-Type", contentType)

	// 设置管理认证头（使用 RSF host）
	host := "rsf.qbox.me"
	authToken := c.generateAuthTokenWithQuery(method, signPath, queryString, host, contentType, nil)
	req.Header.Set("Authorization", authToken)

	return c.httpClient.Do(req)
}

// Upload 上传文件 (使用表单上传)
func (c *Client) Upload(ctx context.Context, key string, reader io.Reader, options *oss.UploadOptions) (*oss.UploadResult, error) {
	// 使用 UploadClient 进行上传
	uploadClient := NewUploadClient(c.config)
	return uploadClient.Upload(ctx, key, reader)
}

// generateToken 生成上传凭证
func (c *Client) generateToken(scope string) string {
	putPolicy := fmt.Sprintf(`{"scope":"%s","deadline":%d}`, scope, time.Now().Add(1*time.Hour).Unix())
	encoded := base64.URLEncoding.EncodeToString([]byte(putPolicy))
	h := hmac.New(sha1.New, []byte(c.config.SecretKey))
	h.Write([]byte(encoded))
	sign := base64.URLEncoding.EncodeToString(h.Sum(nil))
	return c.config.AccessKey + ":" + sign + ":" + encoded
}

func (c *Client) generateUploadToken(key string) string {
	return c.generateToken(c.config.Bucket + ":" + key)
}

func (c *Client) generateBucketToken() string {
	return c.generateToken(c.config.Bucket)
}

// 七牛云临时域名后缀（平台分配的 CDN 域名，稳定性高）
var qiniuTempSuffixes = []string{
	".qiniudns.com", ".clouddn.com", ".qbox.me",
	".qnssl.com", ".qnybgz.cn", ".qiniudns.com.cn",
}

// extractHost 从 URL 提取主机名（去掉 scheme、path、port）
func extractHost(domainURL string) string {
	host := strings.TrimPrefix(domainURL, "http://")
	host = strings.TrimPrefix(host, "https://")
	if idx := strings.Index(host, "/"); idx >= 0 {
		host = host[:idx]
	}
	if h, _, err := net.SplitHostPort(host); err == nil {
		return h
	}
	return host
}

// isTempDomain 判断是否为七牛平台分配的临时域名（后缀匹配）
func (c *Client) isTempDomain(domain string) bool {
	host := strings.ToLower(extractHost(domain))
	for _, s := range qiniuTempSuffixes {
		if strings.HasSuffix(host, s) {
			return true
		}
	}
	return false
}

// classifyDomains 将域名列表分为临时域名和自定义域名
func (c *Client) classifyDomains(domains []string) (tempDomains, customDomains []string) {
	for _, d := range domains {
		if !strings.HasPrefix(d, "http://") && !strings.HasPrefix(d, "https://") {
			d = "http://" + d
		}
		if c.isTempDomain(d) {
			tempDomains = append(tempDomains, d)
		} else {
			customDomains = append(customDomains, d)
		}
	}
	return
}

// resolveDownloadDomain 解析并缓存下载域名
// 策略：API 域名列表（临时优先→自定义）→ 兜底默认 CDN
// 不做 HTTP 探测：Download 使用签名 URL，即使有防盗链也能通过
func (c *Client) resolveDownloadDomain() (string, error) {
	if c.config.DownloadDomain != "" {
		return c.config.DownloadDomain, nil
	}

	domains, err := c.GetBucketDomains(context.Background())

	if err == nil && len(domains) > 0 {
		tempDomains, customDomains := c.classifyDomains(domains)

		// 精准获取桶的真实区域
		c.resolveRegion(tempDomains)

		// 优先使用临时域名（平台分配，稳定性高）
		if len(tempDomains) > 0 {
			d := tempDomains[0]
			c.config.DownloadDomain = d
			return d, nil
		}
		// 降级到自定义域名
		if len(customDomains) > 0 {
			d := customDomains[0]
			c.config.DownloadDomain = d
			return d, nil
		}
	}

	// 无域名 → 兜底默认 CDN（可能不存在，但给一个机会）
	fallback := c.defaultCDNDomain()
	c.config.DownloadDomain = fallback
	return fallback, nil
}

// defaultCDNDomain 构造七牛默认 CDN 域名
func (c *Client) defaultCDNDomain() string {
	return fmt.Sprintf("http://%s-%s.qiniudns.com", c.config.Bucket, c.config.Region)
}

// ClearDownloadDomain 清除缓存的下载域名（下载失败时调用，下次重新解析）
func (c *Client) ClearDownloadDomain() {
	c.config.DownloadDomain = ""
}

// resolveRegion 精准获取桶的真实区域
// 优先从临时域名提取 → 查询 API → 使用配置值兜底
func (c *Client) resolveRegion(tempDomains []string) {
	// 1. 从临时域名提取
	bucketLower := strings.ToLower(c.config.Bucket)
	for _, d := range tempDomains {
		host := extractHost(d)
		host = strings.ToLower(host)
		if !strings.HasPrefix(host, bucketLower+"-") {
			continue
		}
		rest := host[len(bucketLower)+1:]
		if idx := strings.Index(rest, "."); idx > 0 {
			c.config.Region = rest[:idx]
			return
		}
	}

	// 2. 查询七牛 API
	if region, err := c.GetBucketRegion(context.Background()); err == nil && region != "" {
		c.config.Region = region
	}
}

// Download 下载文件（使用签名 URL，绕过防盗链）
func (c *Client) Download(ctx context.Context, key string, writer io.Writer) error {
	signedURL, err := c.GetSignedURL(ctx, key, 1*time.Hour)
	if err != nil {
		return oss.NewError("DOWNLOAD_ERROR", err.Error(), err)
	}

	req, err := http.NewRequestWithContext(ctx, "GET", signedURL, nil)
	if err != nil {
		return oss.NewError("DOWNLOAD_ERROR", "failed to create request", err)
	}

	resp, err := c.httpClient.Do(req)
	if err != nil {
		c.ClearDownloadDomain()
		return oss.NewError("DOWNLOAD_ERROR", "failed to download file", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		c.ClearDownloadDomain()
		body, _ := io.ReadAll(resp.Body)
		return oss.NewError("DOWNLOAD_ERROR",
			fmt.Sprintf("download failed with status %d: %s", resp.StatusCode, string(body[:min(len(body), 200)])), nil)
	}

	_, err = io.Copy(writer, resp.Body)
	if err != nil {
		c.ClearDownloadDomain()
	}
	return err
}

// Delete 删除文件
func (c *Client) Delete(ctx context.Context, key string) error {
	encodedEntry := c.encodeEntry(key)
	path := "/delete/" + encodedEntry

	resp, err := c.doRequest("POST", path, nil)
	if err != nil {
		return oss.NewError("DELETE_ERROR", "failed to delete file", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode == 200 || resp.StatusCode == 612 {
		return nil
	}

	body, _ := io.ReadAll(resp.Body)
	return oss.NewError("DELETE_ERROR", fmt.Sprintf("delete failed with status %d: %s", resp.StatusCode, string(body)), nil)
}

// DeleteMultiple 批量删除文件
func (c *Client) DeleteMultiple(ctx context.Context, keys []string) (*oss.DeleteResult, error) {
	result := &oss.DeleteResult{
		Deleted: make([]string, 0),
		Errors:  make([]string, 0),
	}

	for _, key := range keys {
		if err := c.Delete(ctx, key); err != nil {
			result.Errors = append(result.Errors, key)
		} else {
			result.Deleted = append(result.Deleted, key)
		}
	}

	return result, nil
}

// GetFileInfo 获取文件信息
func (c *Client) GetFileInfo(ctx context.Context, key string) (*oss.FileInfo, error) {
	encodedEntry := c.encodeEntry(key)
	path := "/stat/" + encodedEntry

	resp, err := c.doRequest("GET", path, nil)
	if err != nil {
		return nil, oss.NewError("STAT_ERROR", "failed to get file info", err)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, oss.NewError("STAT_ERROR", "failed to read response", err)
	}

	if resp.StatusCode == 612 {
		return nil, oss.ErrFileNotFound
	}

	if resp.StatusCode != 200 {
		return nil, oss.NewError("STAT_ERROR", fmt.Sprintf("stat failed with status %d: %s", resp.StatusCode, string(body)), nil)
	}

	var statResp struct {
		Hash     string `json:"hash"`
		Fsize    int64  `json:"fsize"`
		MimeType string `json:"mimeType"`
		PutTime  int64  `json:"putTime"`
	}
	if err := json.Unmarshal(body, &statResp); err != nil {
		return nil, oss.NewError("STAT_ERROR", "failed to parse response", err)
	}

	var modTime time.Time
	if statResp.PutTime > 0 {
		modTime = time.Unix(0, statResp.PutTime)
	}

	return &oss.FileInfo{
		Key:          key,
		Size:         statResp.Fsize,
		ETag:         statResp.Hash,
		ContentType:  statResp.MimeType,
		LastModified: modTime,
	}, nil
}

// ListFiles 列举文件
func (c *Client) ListFiles(ctx context.Context, options *oss.ListOptions) (*oss.ListResult, error) {
	if options == nil {
		options = &oss.ListOptions{}
	}

	if options.MaxKeys == 0 {
		options.MaxKeys = 100
	}

	// 构建查询参数
	path := fmt.Sprintf("/list?bucket=%s&limit=%d", c.config.Bucket, options.MaxKeys)
	if options.Prefix != "" {
		path += "&prefix=" + options.Prefix
	}
	if options.Marker != "" {
		path += "&marker=" + options.Marker
	}

	// 使用 GET 方法和 RSF API
	resp, err := c.doRSFRequest("GET", path)
	if err != nil {
		return nil, oss.NewError("LIST_ERROR", "failed to list files", err)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, oss.NewError("LIST_ERROR", "failed to read response", err)
	}

	if resp.StatusCode != 200 {
		return nil, oss.NewError("LIST_ERROR", fmt.Sprintf("list failed with status %d: %s", resp.StatusCode, string(body)), nil)
	}

	// 解析响应
	// 响应格式: {"marker":"","commonPrefixes":[],"items":[{"key":"xxx","hash":"xxx","fsize":123,...}]}
	var listResp struct {
		Marker        string `json:"marker"`
		CommonPrefixes []string `json:"commonPrefixes"`
		Items         []struct {
			Key      string `json:"key"`
			Hash     string `json:"hash"`
			Fsize    int64  `json:"fsize"`
			MimeType string `json:"mimeType"`
			PutTime  int64  `json:"putTime"`
		} `json:"items"`
	}

	if err := json.Unmarshal(body, &listResp); err != nil {
		return nil, oss.NewError("LIST_ERROR", "failed to parse response", err)
	}

	// 转换为统一格式
	files := make([]oss.FileInfo, 0, len(listResp.Items))
	for _, item := range listResp.Items {
		var modTime time.Time
		if item.PutTime > 0 {
			modTime = time.Unix(0, item.PutTime)
		}
		files = append(files, oss.FileInfo{
			Key:          item.Key,
			Size:         item.Fsize,
			ETag:         item.Hash,
			ContentType:  item.MimeType,
			LastModified: modTime,
		})
	}

	return &oss.ListResult{
		Files:       files,
		IsTruncated: listResp.Marker != "",
		NextMarker:  listResp.Marker,
		Prefixes:    listResp.CommonPrefixes,
	}, nil
}

// GetSignedURL 获取预签名URL
// 签名格式: hmac_sha1(SecretKey, "<downloadURL>?e=<deadline>")
func (c *Client) GetSignedURL(ctx context.Context, key string, expiresIn time.Duration) (string, error) {
	deadline := time.Now().Add(expiresIn).Unix()

	baseURL, err := c.resolveDownloadDomain()
	if err != nil {
		return "", err
	}

	// 签名字符串 = 完整 URL + ?e=deadline
	urlToSign := fmt.Sprintf("%s/%s?e=%d", baseURL, key, deadline)
	h := hmac.New(sha1.New, []byte(c.config.SecretKey))
	h.Write([]byte(urlToSign))
	sign := base64.URLEncoding.EncodeToString(h.Sum(nil))

	return fmt.Sprintf("%s&token=%s:%s", urlToSign, c.config.AccessKey, sign), nil
}

// Copy 复制文件
func (c *Client) Copy(ctx context.Context, sourceKey, targetKey string) error {
	sourceEntry := c.encodeEntry(sourceKey)
	targetEntry := c.encodeEntry(targetKey)
	path := "/copy/" + sourceEntry + "/" + targetEntry

	resp, err := c.doRequest("POST", path, nil)
	if err != nil {
		return oss.NewError("COPY_ERROR", "failed to copy file", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode == 200 {
		return nil
	}

	body, _ := io.ReadAll(resp.Body)
	return oss.NewError("COPY_ERROR", fmt.Sprintf("copy failed with status %d: %s", resp.StatusCode, string(body)), nil)
}

// Move 移动/重命名文件
func (c *Client) Move(ctx context.Context, sourceKey, targetKey string) error {
	sourceEntry := c.encodeEntry(sourceKey)
	targetEntry := c.encodeEntry(targetKey)
	path := "/move/" + sourceEntry + "/" + targetEntry

	resp, err := c.doRequest("POST", path, nil)
	if err != nil {
		return oss.NewError("MOVE_ERROR", "failed to move file", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode == 200 {
		return nil
	}

	body, _ := io.ReadAll(resp.Body)
	return oss.NewError("MOVE_ERROR", fmt.Sprintf("move failed with status %d: %s", resp.StatusCode, string(body)), nil)
}

// Exists 检查文件是否存在
func (c *Client) Exists(ctx context.Context, key string) (bool, error) {
	_, err := c.GetFileInfo(ctx, key)
	if err == oss.ErrFileNotFound {
		return false, nil
	}
	if err != nil {
		return false, err
	}
	return true, nil
}

// Close 关闭连接
func (c *Client) Close() error {
	c.httpClient.CloseIdleConnections()
	return nil
}