package handlers

import (
	"crypto/sha256"
	"encoding/hex"
	"io"
	"net/http"
	"strconv"
	"strings"

	"gitea.loveuer.com/loveuer/cluster/internal/registry/storage"

	"github.com/gin-gonic/gin"
)

// GetManifest 获取 manifest
func GetManifest(store storage.Storage) gin.HandlerFunc {
	return func(c *gin.Context) {
		repo := c.GetString("repo_name")
		if repo == "" {
			repo = strings.TrimPrefix(c.Param("name"), "/")
		}
		reference := c.Param("reference")

		data, mediaType, err := store.GetManifest(repo, reference)
		if err != nil {
			c.JSON(http.StatusNotFound, gin.H{
				"errors": []gin.H{
					{
						"code":    "MANIFEST_UNKNOWN",
						"message": err.Error(),
					},
				},
			})
			return
		}

		c.Header("Content-Type", mediaType)
		c.Header("Content-Length", strconv.FormatInt(int64(len(data)), 10))
		c.Header("Docker-Content-Digest", calculateDigest(data))
		c.Data(http.StatusOK, mediaType, data)
	}
}

// PutManifest 推送 manifest
func PutManifest(store storage.Storage) gin.HandlerFunc {
	return func(c *gin.Context) {
		repo := c.Param("name")
		reference := c.Param("reference")

		// 读取请求体
		data, err := io.ReadAll(c.Request.Body)
		if err != nil {
			c.JSON(http.StatusBadRequest, gin.H{
				"errors": []gin.H{
					{
						"code":    "BAD_REQUEST",
						"message": err.Error(),
					},
				},
			})
			return
		}

		// 获取 Content-Type
		mediaType := c.GetHeader("Content-Type")
		if mediaType == "" {
			mediaType = "application/vnd.docker.distribution.manifest.v2+json"
		}

		// 存储 manifest
		if err := store.PutManifest(repo, reference, data, mediaType); err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{
				"errors": []gin.H{
					{
						"code":    "INTERNAL_ERROR",
						"message": err.Error(),
					},
				},
			})
			return
		}

		// 返回 Location 和 Digest
		digest := calculateDigest(data)
		c.Header("Location", c.Request.URL.Path)
		c.Header("Docker-Content-Digest", digest)
		c.Status(http.StatusCreated)
	}
}

// DeleteManifest 删除 manifest
func DeleteManifest(store storage.Storage) gin.HandlerFunc {
	return func(c *gin.Context) {
		repo := c.Param("name")
		reference := c.Param("reference")

		if err := store.DeleteManifest(repo, reference); err != nil {
			c.JSON(http.StatusNotFound, gin.H{
				"errors": []gin.H{
					{
						"code":    "MANIFEST_UNKNOWN",
						"message": err.Error(),
					},
				},
			})
			return
		}

		c.Status(http.StatusAccepted)
	}
}

// HeadManifest 检查 manifest 是否存在
func HeadManifest(store storage.Storage) gin.HandlerFunc {
	return func(c *gin.Context) {
		repo := c.GetString("repo_name")
		if repo == "" {
			repo = strings.TrimPrefix(c.Param("name"), "/")
		}
		reference := c.Param("reference")

		exists, err := store.ManifestExists(repo, reference)
		if err != nil || !exists {
			c.Status(http.StatusNotFound)
			return
		}

		// 获取 manifest 以设置正确的 headers
		data, mediaType, err := store.GetManifest(repo, reference)
		if err != nil {
			c.Status(http.StatusNotFound)
			return
		}

		c.Header("Content-Type", mediaType)
		c.Header("Content-Length", strconv.FormatInt(int64(len(data)), 10))
		c.Header("Docker-Content-Digest", calculateDigest(data))
		c.Status(http.StatusOK)
	}
}

// calculateDigest 计算 SHA256 digest
func calculateDigest(data []byte) string {
	hash := sha256.Sum256(data)
	return "sha256:" + hex.EncodeToString(hash[:])
}