package registry

import (
	"bytes"
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"io"
	"log"
	"strconv"
	"strings"

	"gitea.loveuer.com/loveuer/cluster/pkg/model/registry"
	"gitea.loveuer.com/loveuer/cluster/pkg/resp"
	"gitea.loveuer.com/loveuer/cluster/pkg/store"
	"github.com/gofiber/fiber/v3"
	"gorm.io/gorm"
)

// HandleBlobs ?? blob ????
// POST /v2/{repo}/blobs/uploads/ - ????
// PATCH /v2/{repo}/blobs/uploads/{uuid} - ?????
// PUT /v2/{repo}/blobs/uploads/{uuid}?digest={digest} - ????
// GET /v2/{repo}/blobs/{digest} - ?? blob
// HEAD /v2/{repo}/blobs/{digest} - ?? blob ????
func HandleBlobs(c fiber.Ctx, db *gorm.DB, store store.Store) error {
	path := c.Path()
	method := c.Method()

	// ????: /v2/{repo}/blobs/...
	// ??????????? "test/redis"
	pathWithoutV2 := strings.TrimPrefix(path, "/v2/")
	parts := strings.Split(pathWithoutV2, "/")
	if len(parts) < 2 {
		return resp.R404(c, "INVALID_PATH", nil, "invalid path")
	}

	// ?? "blobs" ????????????????
	blobsIndex := -1
	for i, part := range parts {
		if part == "blobs" {
			blobsIndex = i
			break
		}
	}
	if blobsIndex < 1 {
		return resp.R404(c, "INVALID_PATH", nil, "invalid path: blobs not found")
	}

	// ???? blobs ???????
	repo := strings.Join(parts[:blobsIndex], "/")
	
	// Strip registry_address prefix from repo if present
	var registryConfig registry.RegistryConfig
	registryAddress := ""
	if err := db.Where("key = ?", "registry_address").First(&registryConfig).Error; err == nil {
		registryAddress = registryConfig.Value
	}
	if registryAddress != "" && strings.HasPrefix(repo, registryAddress+"/") {
		repo = strings.TrimPrefix(repo, registryAddress+"/")
	}
	// ???? parts??????????? parts[0] ? "blobs"
	parts = parts[blobsIndex:]

	switch method {
	case "POST":
		// POST /v2/{repo}/blobs/uploads/ - ????
		// parts ??? ["blobs", "uploads", ""] ? ["blobs", "uploads"]
		if len(parts) >= 2 && parts[0] == "blobs" && parts[1] == "uploads" {
			return handleBlobUploadStart(c, db, store, repo)
		}

	case "PATCH":
		// PATCH /v2/{repo}/blobs/uploads/{uuid} - ?????
		// parts ??? ["blobs", "uploads", "uuid"]
		if len(parts) >= 3 && parts[0] == "blobs" && parts[1] == "uploads" {
			uuid := parts[2]
			return handleBlobUploadChunk(c, db, store, repo, uuid)
		}

	case "PUT":
		// PUT /v2/{repo}/blobs/uploads/{uuid}?digest={digest} - ????
		// parts ??? ["blobs", "uploads", "uuid"]
		if len(parts) >= 3 && parts[0] == "blobs" && parts[1] == "uploads" {
			uuid := parts[2]
			digest := c.Query("digest")
			if digest == "" {
				return resp.R400(c, "MISSING_DIGEST", nil, "digest parameter is required")
			}
			return handleBlobUploadComplete(c, db, store, repo, uuid, digest)
		}

	case "GET":
		// GET /v2/{repo}/blobs/{digest} - ?? blob
		// parts ??? ["blobs", "digest"]
		if len(parts) >= 2 && parts[0] == "blobs" {
			digest := parts[1]
			return handleBlobDownload(c, db, store, repo, digest)
		}

	case "HEAD":
		// HEAD /v2/{repo}/blobs/{digest} - ?? blob ????
		// parts ??? ["blobs", "digest"]
		if len(parts) >= 2 && parts[0] == "blobs" {
			digest := parts[1]
			return handleBlobHead(c, db, store, repo, digest)
		}
	}

	return resp.R404(c, "NOT_FOUND", nil, "endpoint not found")
}

// handleBlobUploadStart ?? blob ??
func handleBlobUploadStart(c fiber.Ctx, db *gorm.DB, store store.Store, repo string) error {
	// ?? UUID
	uuidBytes := make([]byte, 16)
	if _, err := rand.Read(uuidBytes); err != nil {
		return resp.R500(c, "", nil, err)
	}
	uuid := hex.EncodeToString(uuidBytes)

	// ??????
	upload := &registry.BlobUpload{
		UUID:       uuid,
		Repository: repo,
		Path:       uuid, // ?? UUID ??????
		Size:       0,
	}

	if err := db.Create(upload).Error; err != nil {
		return resp.R500(c, "", nil, err)
	}

	// ??????
	w, err := store.CreateUpload(c.Context(), uuid)
	if err != nil {
		db.Delete(upload)
		return resp.R500(c, "", nil, err)
	}
	w.Close()

	// ???? URL
	uploadURL := fmt.Sprintf("/v2/%s/blobs/uploads/%s", repo, uuid)
	c.Set("Location", uploadURL)
	c.Set("Docker-Upload-UUID", uuid)
	c.Set("Range", "0-0")
	return c.SendStatus(202)
}

// handleBlobUploadChunk ?? blob ???
func handleBlobUploadChunk(c fiber.Ctx, db *gorm.DB, store store.Store, repo string, uuid string) error {
	// ??????
	var upload registry.BlobUpload
	if err := db.Where("uuid = ? AND repository = ?", uuid, repo).First(&upload).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			return resp.R404(c, "UPLOAD_NOT_FOUND", nil, "upload session not found")
		}
		return resp.R500(c, "", nil, err)
	}

	// ?????
	body := c.Body()
	if len(body) == 0 {
		return resp.R400(c, "EMPTY_BODY", nil, "request body is empty")
	}

	// ??????? bytes.NewReader ????????
	n, err := store.AppendUpload(c.Context(), uuid, bytes.NewReader(body))
	if err != nil {
		return resp.R500(c, "", nil, err)
	}

	// ??????
	upload.Size += n
	if err := db.Save(&upload).Error; err != nil {
		return resp.R500(c, "", nil, err)
	}

	// ???? URL ???
	uploadURL := fmt.Sprintf("/v2/%s/blobs/uploads/%s", repo, uuid)
	c.Set("Location", uploadURL)
	c.Set("Docker-Upload-UUID", uuid)
	c.Set("Range", fmt.Sprintf("0-%d", upload.Size-1))
	return c.SendStatus(202)
}

// handleBlobUploadComplete ?? blob ??
func handleBlobUploadComplete(c fiber.Ctx, db *gorm.DB, store store.Store, repo string, uuid string, digest string) error {
	// ??????
	var upload registry.BlobUpload
	if err := db.Where("uuid = ? AND repository = ?", uuid, repo).First(&upload).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			return resp.R404(c, "UPLOAD_NOT_FOUND", nil, "upload session not found")
		}
		return resp.R500(c, "", nil, err)
	}

	// ??????????????PUT ???????????
	body := c.Body()
	if len(body) > 0 {
		if _, err := store.AppendUpload(c.Context(), uuid, bytes.NewReader(body)); err != nil {
			return resp.R500(c, "", nil, err)
		}
	}

	// ?????????????
	if err := store.FinalizeUpload(c.Context(), uuid, digest); err != nil {
		return resp.R500(c, "", nil, err)
	}

	// ????????
	size, err := store.GetBlobSize(c.Context(), digest)
	if err != nil {
		return resp.R500(c, "", nil, err)
	}

	// ????? blob ??
	var blob registry.Blob
	if err := db.Where("digest = ?", digest).First(&blob).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			blob = registry.Blob{
				Digest:     digest,
				Size:       size,
				Repository: repo,
			}
			if err := db.Create(&blob).Error; err != nil {
				return resp.R500(c, "", nil, err)
			}
		} else {
			return resp.R500(c, "", nil, err)
		}
	}

	// ??????
	db.Delete(&upload)
	store.DeleteUpload(c.Context(), uuid)

	// ?? blob URL
	blobURL := fmt.Sprintf("/v2/%s/blobs/%s", repo, digest)
	c.Set("Location", blobURL)
	c.Set("Content-Length", fmt.Sprintf("%d", size))
	c.Set("Docker-Content-Digest", digest)
	return c.SendStatus(201)
}

// parseRangeHeader parses Range header and returns start and end positions
func parseRangeHeader(rangeHeader string, size int64) (start, end int64, valid bool) {
	if rangeHeader == "" {
		return 0, size - 1, false
	}

	// Range header format: "bytes=start-end" or "bytes=start-"
	if !strings.HasPrefix(rangeHeader, "bytes=") {
		return 0, size - 1, false
	}

	rangeSpec := strings.TrimPrefix(rangeHeader, "bytes=")
	parts := strings.Split(rangeSpec, "-")
	if len(parts) != 2 {
		return 0, size - 1, false
	}

	var err error
	if parts[0] == "" {
		// Suffix range: "bytes=-suffix"
		suffix, err := strconv.ParseInt(parts[1], 10, 64)
		if err != nil || suffix <= 0 {
			return 0, size - 1, false
		}
		start = size - suffix
		if start < 0 {
			start = 0
		}
		end = size - 1
	} else if parts[1] == "" {
		// Start range: "bytes=start-"
		start, err = strconv.ParseInt(parts[0], 10, 64)
		if err != nil || start < 0 || start >= size {
			return 0, size - 1, false
		}
		end = size - 1
	} else {
		// Full range: "bytes=start-end"
		start, err = strconv.ParseInt(parts[0], 10, 64)
		if err != nil || start < 0 || start >= size {
			return 0, size - 1, false
		}
		end, err = strconv.ParseInt(parts[1], 10, 64)
		if err != nil || end < start || end >= size {
			return 0, size - 1, false
		}
	}

	return start, end, true
}

// handleBlobDownload ?? blob
func handleBlobDownload(c fiber.Ctx, db *gorm.DB, store store.Store, repo string, digest string) error {
	log.Printf("[BlobDownload] Start: repo=%s, digest=%s", repo, digest)
	
	// Check if blob exists
	exists, err := store.BlobExists(c.Context(), digest)
	if err != nil {
		log.Printf("[BlobDownload] BlobExists error: %v", err)
		return resp.R500(c, "", nil, err)
	}
	if !exists {
		log.Printf("[BlobDownload] Blob not found: %s", digest)
		return resp.R404(c, "BLOB_NOT_FOUND", nil, "blob not found")
	}

	// Get blob size
	size, err := store.GetBlobSize(c.Context(), digest)
	if err != nil {
		log.Printf("[BlobDownload] GetBlobSize error: %v", err)
		return resp.R500(c, "", nil, err)
	}
	log.Printf("[BlobDownload] Blob size: %d bytes", size)

	// Read blob
	reader, err := store.ReadBlob(c.Context(), digest)
	if err != nil {
		log.Printf("[BlobDownload] ReadBlob error: %v", err)
		return resp.R500(c, "", nil, err)
	}
	defer reader.Close()
	log.Printf("[BlobDownload] Reader opened successfully")

	// Check for Range request
	rangeHeader := c.Get("Range")
	start, end, hasRange := parseRangeHeader(rangeHeader, size)

	if hasRange {
		log.Printf("[BlobDownload] Range request: %d-%d/%d", start, end, size)
		// Handle Range request
		// Seek to start position
		if seeker, ok := reader.(io.Seeker); ok {
			if _, err := seeker.Seek(start, io.SeekStart); err != nil {
				log.Printf("[BlobDownload] Seek error: %v", err)
				return resp.R500(c, "", nil, err)
			}
		} else {
			// If not seekable, read and discard bytes
			if _, err := io.CopyN(io.Discard, reader, start); err != nil {
				log.Printf("[BlobDownload] CopyN discard error: %v", err)
				return resp.R500(c, "", nil, err)
			}
		}

		// Create limited reader
		limitedReader := io.LimitReader(reader, end-start+1)

		// Set partial content headers
		c.Set("Content-Type", "application/octet-stream")
		c.Set("Content-Length", fmt.Sprintf("%d", end-start+1))
		c.Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", start, end, size))
		c.Set("Accept-Ranges", "bytes")
		c.Set("Docker-Content-Digest", digest)
		c.Status(206) // Partial Content

		log.Printf("[BlobDownload] Sending partial content")
		// Read all content and send
		content, err := io.ReadAll(limitedReader)
		if err != nil {
			log.Printf("[BlobDownload] ReadAll error: %v", err)
			return resp.R500(c, "", nil, err)
		}
		return c.Send(content)
	}

	// Full blob download
	log.Printf("[BlobDownload] Full blob download, setting headers")
	c.Set("Content-Type", "application/octet-stream")
	c.Set("Content-Length", fmt.Sprintf("%d", size))
	c.Set("Accept-Ranges", "bytes")
	c.Set("Docker-Content-Digest", digest)

	log.Printf("[BlobDownload] About to read all content, size=%d", size)
	// Read all content and send
	content, err := io.ReadAll(reader)
	if err != nil {
		log.Printf("[BlobDownload] ReadAll error: %v", err)
		return resp.R500(c, "", nil, err)
	}
	log.Printf("[BlobDownload] Read %d bytes, sending...", len(content))
	return c.Send(content)
}

// handleBlobHead ?? blob ????
func handleBlobHead(c fiber.Ctx, db *gorm.DB, store store.Store, repo string, digest string) error {
	// Check if blob exists
	exists, err := store.BlobExists(c.Context(), digest)
	if err != nil {
		return resp.R500(c, "", nil, err)
	}
	if !exists {
		return resp.R404(c, "BLOB_NOT_FOUND", nil, "blob not found")
	}

	// Get blob size
	size, err := store.GetBlobSize(c.Context(), digest)
	if err != nil {
		return resp.R500(c, "", nil, err)
	}

	// Set response headers
	c.Set("Content-Type", "application/octet-stream")
	c.Set("Content-Length", fmt.Sprintf("%d", size))
	c.Set("Accept-Ranges", "bytes")
	c.Set("Docker-Content-Digest", digest)
	return c.SendStatus(200)
}