package oci

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"mime/multipart"
	"net/http"
	"net/url"
	"strings"
)

// domainImagesPath 是身份域公开图片上传端点(品牌 / IdP 图标),SDK 未覆盖该操作。
const domainImagesPath = "/storage/v1/Images"

// UploadDomainImage 实现 Client:上传公开图片到身份域存储,返回公网 fileUrl
// 与域存储内文件名(后者留作后续精确清理)。借 domainsClient 的 BaseClient
// 发裸 multipart 请求,OCI 签名与代理配置直接复用。
func (c *RealClient) UploadDomainImage(ctx context.Context, cred Credentials, region, domainID, fileName string, data []byte) (string, string, error) {
	dc, err := c.domainsClient(ctx, cred, region, domainID)
	if err != nil {
		return "", "", err
	}
	req, err := newDomainImageUploadRequest(ctx, dc.Endpoint(), fileName, data)
	if err != nil {
		return "", "", err
	}
	resp, callErr := dc.BaseClient.Call(ctx, req)
	return parseImageUploadResponse(resp, callErr)
}

// DeleteDomainImage 实现 Client:按响应 fileName 精确删除公开图片,404 视为幂等成功。
func (c *RealClient) DeleteDomainImage(ctx context.Context, cred Credentials, region, domainID, fileName string) error {
	dc, err := c.domainsClient(ctx, cred, region, domainID)
	if err != nil {
		return err
	}
	req, err := newDomainImageDeleteRequest(ctx, dc.Endpoint(), fileName)
	if err != nil {
		return err
	}
	resp, callErr := dc.BaseClient.Call(ctx, req)
	return finishDomainImageDelete(resp, callErr)
}

func newDomainImageUploadRequest(ctx context.Context, endpoint, fileName string, data []byte) (*http.Request, error) {
	body, contentType, err := imageMultipart(fileName, data)
	if err != nil {
		return nil, err
	}
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, strings.TrimRight(endpoint, "/")+domainImagesPath, bytes.NewReader(body))
	if err != nil {
		return nil, fmt.Errorf("build image upload request: %w", err)
	}
	req.Header.Set("Content-Type", contentType)
	return req, nil
}

func newDomainImageDeleteRequest(ctx context.Context, endpoint, fileName string) (*http.Request, error) {
	u, err := url.Parse(strings.TrimRight(endpoint, "/") + domainImagesPath)
	if err != nil {
		return nil, fmt.Errorf("build image delete URL: %w", err)
	}
	query := u.Query()
	query.Set("fileName", fileName)
	u.RawQuery = query.Encode()
	req, err := http.NewRequestWithContext(ctx, http.MethodDelete, u.String(), nil)
	if err != nil {
		return nil, fmt.Errorf("build image delete request: %w", err)
	}
	return req, nil
}

// imageMultipart 组装上传请求体:file(二进制)与 fileName 两个 part(官方文档要求)。
func imageMultipart(fileName string, data []byte) ([]byte, string, error) {
	var buf bytes.Buffer
	w := multipart.NewWriter(&buf)
	fw, err := w.CreateFormFile("file", fileName)
	if err != nil {
		return nil, "", fmt.Errorf("build image multipart: %w", err)
	}
	if _, err := fw.Write(data); err != nil {
		return nil, "", fmt.Errorf("build image multipart: %w", err)
	}
	if err := w.WriteField("fileName", fileName); err != nil {
		return nil, "", fmt.Errorf("build image multipart: %w", err)
	}
	if err := w.Close(); err != nil {
		return nil, "", fmt.Errorf("build image multipart: %w", err)
	}
	return buf.Bytes(), w.FormDataContentType(), nil
}

// parseImageUploadResponse 解析上传响应,并确保任何返回路径都关闭响应体。
func parseImageUploadResponse(resp *http.Response, callErr error) (string, string, error) {
	if resp != nil && resp.Body != nil {
		defer drainAndClose(resp.Body)
	}
	if callErr != nil {
		return "", "", fmt.Errorf("upload domain image: %w", callErr)
	}
	if resp == nil || resp.Body == nil {
		return "", "", fmt.Errorf("upload domain image: empty response")
	}
	if resp.StatusCode != http.StatusCreated && resp.StatusCode != http.StatusOK {
		return "", "", fmt.Errorf("upload domain image: HTTP %d", resp.StatusCode)
	}
	b, err := io.ReadAll(io.LimitReader(resp.Body, (1<<20)+1))
	if err != nil {
		return "", "", fmt.Errorf("read image upload response: %w", err)
	}
	if len(b) > 1<<20 {
		return "", "", fmt.Errorf("upload domain image: response exceeds 1MB")
	}
	return decodeImageUploadResponse(b)
}

func decodeImageUploadResponse(data []byte) (string, string, error) {
	var out struct {
		FileURL  string `json:"fileUrl"`
		FileName string `json:"fileName"`
	}
	if err := json.Unmarshal(data, &out); err != nil {
		return "", "", fmt.Errorf("parse image upload response: %w", err)
	}
	if out.FileURL == "" || out.FileName == "" {
		return "", "", fmt.Errorf("upload domain image: response missing fileUrl or fileName")
	}
	return out.FileURL, out.FileName, nil
}

func finishDomainImageDelete(resp *http.Response, callErr error) error {
	if resp != nil && resp.Body != nil {
		defer drainAndClose(resp.Body)
	}
	if resp != nil && resp.StatusCode == http.StatusNotFound {
		return nil
	}
	if callErr != nil {
		return fmt.Errorf("delete domain image: %w", callErr)
	}
	if resp == nil {
		return fmt.Errorf("delete domain image: empty response")
	}
	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusNoContent {
		return fmt.Errorf("delete domain image: HTTP %d", resp.StatusCode)
	}
	return nil
}

// drainAndClose 读完小响应以便 HTTP 连接复用;超大异常响应限制为 64KiB。
func drainAndClose(body io.ReadCloser) {
	_, _ = io.Copy(io.Discard, io.LimitReader(body, 64<<10))
	_ = body.Close()
}