package qiniu

import (
	"bytes"
	"context"
	"crypto/hmac"
	"crypto/sha1"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"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, as0=亚太0区
	UseHTTPS  bool   // 是否使用 HTTPS
	UploadDomain string // 上传域名（可选，默认根据 Region 自动选择）
}

// 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
}

// generateSignature 生成七牛云管理凭证签名
// 根据官方文档：https://developer.qiniu.com/kodo/1201/access-token
func (c *Client) generateSignature(method, path, host, contentType string, body []byte) string {
	// 七牛云管理凭证签名格式:
	// signingStr = Method + " " + Path + "\nHost: " + Host + "\n" + [Content-Type] + "\n\n" + [body]
	var signingStr string

	// 1. Method + " " + Path
	signingStr = method + " " + path

	// 2. Host header
	signingStr += "\nHost: " + host

	// 3. Content-Type header (如果设置了)
	if contentType != "" {
		signingStr += "\nContent-Type: " + contentType
	}

	// 4. 两个连续换行符
	signingStr += "\n\n"

	// 5. Body (如果设置了 Content-Type 且不是 application/octet-stream)
	if contentType != "" && contentType != "application/octet-stream" && len(body) > 0 {
		signingStr += string(body)
	}

	// 使用 HMAC-SHA1 签名
	h := hmac.New(sha1.New, []byte(c.config.SecretKey))
	h.Write([]byte(signingStr))

	// Base64 URL 安全编码
	signature := base64.URLEncoding.EncodeToString(h.Sum(nil))

	return signature
}

// generateAuthToken 生成管理认证 Token
func (c *Client) generateAuthToken(method, path, host, contentType string, body []byte) string {
	signature := c.generateSignature(method, path, host, contentType, body)
	return "Qiniu " + c.config.AccessKey + ":" + signature
}

// generateAuthTokenWithQuery 生成管理认证 Token（支持 query string）
func (c *Client) generateAuthTokenWithQuery(method, path, query, host, contentType string, body []byte) string {
	// 七牛云管理凭证签名格式:
	// 如果 query 为非空字符串: signingStr = Method + " " + Path + "?" + query + "\nHost: " + Host + ...
	// 如果 query 为空: signingStr = Method + " " + Path + "\nHost: " + Host + ...
	var signingStr string

	// 1. Method + " " + Path
	signingStr = method + " " + path

	// 2. Query string (如果有)
	if query != "" {
		signingStr += "?" + query
	}

	// 3. Host header
	signingStr += "\nHost: " + host

	// 4. Content-Type header (如果设置了)
	if contentType != "" {
		signingStr += "\nContent-Type: " + contentType
	}

	// 5. 两个连续换行符
	signingStr += "\n\n"

	// 6. Body (如果设置了 Content-Type 且不是 application/octet-stream)
	if contentType != "" && contentType != "application/octet-stream" && len(body) > 0 {
		signingStr += string(body)
	}

	// 使用 HMAC-SHA1 签名
	h := hmac.New(sha1.New, []byte(c.config.SecretKey))
	h.Write([]byte(signingStr))

	// Base64 URL 安全编码
	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 {
	// 如果配置了自定义上传域名，使用自定义的
	if c.config.UploadDomain != "" {
		if c.config.UseHTTPS {
			return "https://" + c.config.UploadDomain
		}
		return "http://" + c.config.UploadDomain
	}

	// 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)
}

// generateUploadToken 生成上传凭证
func (c *Client) generateUploadToken(key string) string {
	// 七牛云上传凭证的生成
	// 1. 创建 putPolicy
	putPolicy := fmt.Sprintf(`{"scope":"%s:%s","deadline":%d}`,
		c.config.Bucket, key, time.Now().Add(1*time.Hour).Unix())

	// 2. 对 putPolicy 进行 base64 URL 编码
	encodedPutPolicy := base64.URLEncoding.EncodeToString([]byte(putPolicy))

	// 3. 对 encodedPutPolicy 进行 HMAC-SHA1 签名
	h := hmac.New(sha1.New, []byte(c.config.SecretKey))
	h.Write([]byte(encodedPutPolicy))
	encodedSign := base64.URLEncoding.EncodeToString(h.Sum(nil))

	// 4. 组合 token
	return c.config.AccessKey + ":" + encodedSign + ":" + encodedPutPolicy
}

// generateBucketToken 生成 bucket 级别的上传凭证（用于分片上传 v2）
func (c *Client) generateBucketToken() string {
	// 分片上传 v2 需要 bucket 级别的 token
	// 1. 创建 putPolicy
	putPolicy := fmt.Sprintf(`{"scope":"%s","deadline":%d}`,
		c.config.Bucket, time.Now().Add(1*time.Hour).Unix())

	// 2. 对 putPolicy 进行 base64 URL 编码
	encodedPutPolicy := base64.URLEncoding.EncodeToString([]byte(putPolicy))

	// 3. 对 encodedPutPolicy 进行 HMAC-SHA1 签名
	h := hmac.New(sha1.New, []byte(c.config.SecretKey))
	h.Write([]byte(encodedPutPolicy))
	encodedSign := base64.URLEncoding.EncodeToString(h.Sum(nil))

	// 4. 组合 token
	return c.config.AccessKey + ":" + encodedSign + ":" + encodedPutPolicy
}

// resolveDownloadDomain 解析并缓存下载域名
func (c *Client) resolveDownloadDomain() (string, error) {
	if c.config.UploadDomain != "" {
		return c.config.UploadDomain, nil
	}
	domains, err := c.GetBucketDomains(context.Background())
	if err != nil || len(domains) == 0 {
		return "", fmt.Errorf("无法获取桶 %s 的下载域名: %v", c.config.Bucket, err)
	}
	domain := domains[0]
	if !strings.HasPrefix(domain, "http://") && !strings.HasPrefix(domain, "https://") {
		domain = "http://" + domain
	}
	c.config.UploadDomain = domain
	return domain, nil
}

// Download 下载文件
func (c *Client) Download(ctx context.Context, key string, writer io.Writer) error {
	baseURL, err := c.resolveDownloadDomain()
	if err != nil {
		return oss.NewError("DOWNLOAD_ERROR", err.Error(), err)
	}
	url := fmt.Sprintf("%s/%s", baseURL, key)

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

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

	if resp.StatusCode != 200 {
		return oss.NewError("DOWNLOAD_ERROR", fmt.Sprintf("download failed with status %d", resp.StatusCode), nil)
	}

	_, err = io.Copy(writer, resp.Body)
	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)
	}

	// 解析响应 (简化实现)
	// 实际响应格式: {"hash":"xxx","fsize":123,"mimeType":"xxx","putTime":123}
	// 这里返回一个简化的 FileInfo
	return &oss.FileInfo{
		Key: key,
	}, 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 {
		files = append(files, oss.FileInfo{
			Key:         item.Key,
			Size:        item.Fsize,
			ETag:        item.Hash,
			ContentType: item.MimeType,
		})
	}

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

// GetSignedURL 获取预签名URL
func (c *Client) GetSignedURL(ctx context.Context, key string, expiresIn time.Duration) (string, error) {
	// 七牛云私有空间下载需要生成私有下载 URL
	deadline := time.Now().Add(expiresIn).Unix()

	// 构建 download URL
	baseURL, err := c.resolveDownloadDomain()
	if err != nil {
		return "", err
	}
	downloadURL := fmt.Sprintf("%s/%s", baseURL, key)

	// 生成签名
	h := hmac.New(sha1.New, []byte(c.config.SecretKey))
	signStr := fmt.Sprintf("%s\n%d", downloadURL, deadline)
	h.Write([]byte(signStr))
	sign := base64.URLEncoding.EncodeToString(h.Sum(nil))

	// 构建最终 URL
	signedURL := fmt.Sprintf("%s?e=%d&token=%s:%s", downloadURL, deadline, c.config.AccessKey, sign)

	return signedURL, 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
}