package registry

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"time"

	"scout/pkg/scoutpkg"
)

var allowedChannels = map[string]bool{
	"stable": true,
	"beta":   true,
	"dev":    true,
}

var allowedStatuses = map[string]bool{
	"draft":      true,
	"published":  true,
	"deprecated": true,
	"revoked":    true,
}

func (r *Registry) AddPackage(input Package, data io.Reader) (Package, error) {
	target := Target{
		Platform:     input.Platform,
		Architecture: input.Architecture,
		PackageType:  input.PackageType,
		FileName:     input.FileName,
	}
	return r.AddArtifact(input, target, data)
}

func (r *Registry) AddArtifact(input Package, target Target, data io.Reader) (Package, error) {
	if data == nil {
		return Package{}, errors.New("\u5305\u6587\u4ef6\u4e0d\u80fd\u4e3a\u7a7a")
	}
	if err := normalizeRelease(&input); err != nil {
		return Package{}, err
	}
	if target.FileName == "" {
		target.FileName = input.FileName
	}
	if target.FileName == "" {
		target.FileName = input.Name + "-" + input.Version + ".pkg"
	}
	if err := normalizeTarget(&target, input.PackageType); err != nil {
		return Package{}, err
	}

	r.writeMu.Lock()
	defer r.writeMu.Unlock()

	stored := r.release(input.Name, input.Version)
	if stored.Name == "" {
		stored = input
		stored.Targets = nil
	} else if err := mergeReleaseMetadata(&stored, input); err != nil {
		return Package{}, err
	}
	for _, existing := range stored.Targets {
		if existing.ID == target.ID {
			return Package{}, errors.New("\u8be5\u7248\u672c\u7684\u5e73\u53f0\u3001\u67b6\u6784\u548c\u5305\u7c7b\u578b\u5df2\u7ecf\u5b58\u5728")
		}
	}

	versionDir := filepath.Join(r.root, input.Name, input.Version)
	if err := os.MkdirAll(versionDir, 0o755); err != nil {
		return Package{}, fmt.Errorf("\u521b\u5efa\u7248\u672c\u76ee\u5f55\u5931\u8d25: %w", err)
	}
	tempPath, size, digest, err := writeTemporaryArtifact(versionDir, data)
	if err != nil {
		return Package{}, err
	}
	defer os.Remove(tempPath)

	target.Size = size
	target.SHA256 = digest
	target.ArtifactID = target.ID
	artifactDir := filepath.Join(versionDir, "artifacts", target.ArtifactID)
	if _, err := os.Stat(artifactDir); err == nil {
		return Package{}, errors.New("\u8be5\u4ea7\u7269\u5df2\u7ecf\u5b58\u5728")
	} else if !os.IsNotExist(err) {
		return Package{}, fmt.Errorf("\u68c0\u67e5\u4ea7\u7269\u76ee\u5f55\u5931\u8d25: %w", err)
	}
	if err := saveArtifact(artifactDir, tempPath, target); err != nil {
		return Package{}, err
	}

	stored.Targets = append(stored.Targets, target)
	stored.UploadedAt = time.Now().UTC()
	applyTarget(&stored, target)
	if err := r.persistRelease(stored); err != nil {
		return Package{}, err
	}
	r.storeRelease(stored)

	result := stored
	result.Targets = []Target{target}
	applyTarget(&result, target)
	r.broadcast(result)
	return result, nil
}

func (r *Registry) AddScoutPackage(input Package, targets []Target, data io.Reader) (Package, error) {
	if data == nil {
		return Package{}, errors.New("Scout \u5305\u6587\u4ef6\u4e0d\u80fd\u4e3a\u7a7a")
	}
	if err := normalizeRelease(&input); err != nil {
		return Package{}, err
	}
	if len(targets) == 0 {
		return Package{}, errors.New("Scout \u5305\u81f3\u5c11\u9700\u8981\u4e00\u4e2a\u76ee\u6807")
	}
	seen := make(map[string]bool)
	for index := range targets {
		if targets[index].FileName == "" {
			targets[index].FileName = input.FileName
		}
		if err := normalizeTarget(&targets[index], input.PackageType); err != nil {
			return Package{}, err
		}
		if seen[targets[index].ID] {
			return Package{}, errors.New("Scout \u5305\u6e05\u5355\u4e2d\u5b58\u5728\u91cd\u590d\u76ee\u6807")
		}
		seen[targets[index].ID] = true
	}

	r.writeMu.Lock()
	defer r.writeMu.Unlock()

	stored := r.release(input.Name, input.Version)
	if stored.Name == "" {
		stored = input
		stored.Targets = nil
	} else if err := mergeReleaseMetadata(&stored, input); err != nil {
		return Package{}, err
	}
	for _, existing := range stored.Targets {
		if seen[existing.ID] {
			return Package{}, errors.New("Scout \u5305\u4e2d\u7684\u67d0\u4e2a\u5e73\u53f0\u76ee\u6807\u5df2\u7ecf\u5b58\u5728")
		}
	}

	versionDir := filepath.Join(r.root, input.Name, input.Version)
	if err := os.MkdirAll(versionDir, 0o755); err != nil {
		return Package{}, fmt.Errorf("\u521b\u5efa\u7248\u672c\u76ee\u5f55\u5931\u8d25: %w", err)
	}
	tempPath, size, digest, err := writeTemporaryArtifact(versionDir, data)
	if err != nil {
		return Package{}, err
	}
	defer os.Remove(tempPath)
	artifactID := "scout-" + digest[:16]
	artifactDir := filepath.Join(versionDir, "artifacts", artifactID)
	if _, err := os.Stat(artifactDir); err == nil {
		return Package{}, errors.New("\u8be5 Scout \u4ea7\u7269\u5df2\u7ecf\u5b58\u5728")
	} else if !os.IsNotExist(err) {
		return Package{}, fmt.Errorf("\u68c0\u67e5 Scout \u4ea7\u7269\u5931\u8d25: %w", err)
	}
	artifactMetadata := targets[0]
	artifactMetadata.ID = artifactID
	artifactMetadata.ArtifactID = artifactID
	artifactMetadata.Size = size
	artifactMetadata.SHA256 = digest
	if err := saveArtifact(artifactDir, tempPath, artifactMetadata); err != nil {
		return Package{}, err
	}
	for index := range targets {
		targets[index].ArtifactID = artifactID
		targets[index].Size = size
		targets[index].SHA256 = digest
	}

	stored.Targets = append(stored.Targets, targets...)
	stored.UploadedAt = time.Now().UTC()
	applyTarget(&stored, targets[0])
	if err := r.persistRelease(stored); err != nil {
		return Package{}, err
	}
	r.storeRelease(stored)

	result := stored
	result.Targets = append([]Target(nil), targets...)
	applyTarget(&result, targets[0])
	r.broadcast(result)
	return result, nil
}

func (r *Registry) LatestFor(name, platform, architecture, channel, currentVersion string) (Package, bool) {
	r.mu.RLock()
	versions := make([]Package, 0, len(r.packages[name]))
	for _, item := range r.packages[name] {
		versions = append(versions, clonePackage(item))
	}
	r.mu.RUnlock()
	sort.Slice(versions, func(left, right int) bool {
		return CompareVersions(versions[left].Version, versions[right].Version) > 0
	})
	for _, item := range versions {
		if !releaseVisible(item, channel) {
			continue
		}
		selected, ok := SelectTarget(item, platform, architecture, currentVersion)
		if ok {
			return selected, true
		}
	}
	return Package{}, false
}

func (r *Registry) LatestForVersion(name, version, platform, architecture, channel, currentVersion string) (Package, bool) {
	return r.GetFor(name, version, platform, architecture, channel, currentVersion)
}

func (r *Registry) VersionsFor(name, platform, architecture, channel, currentVersion string) []Package {
	r.mu.RLock()
	versions := make([]Package, 0, len(r.packages[name]))
	for _, item := range r.packages[name] {
		versions = append(versions, clonePackage(item))
	}
	r.mu.RUnlock()
	result := make([]Package, 0, len(versions))
	for _, item := range versions {
		if !releaseVisible(item, channel) {
			continue
		}
		if selected, ok := SelectTarget(item, platform, architecture, currentVersion); ok {
			result = append(result, selected)
		}
	}
	sort.Slice(result, func(left, right int) bool {
		return CompareVersions(result[left].Version, result[right].Version) > 0
	})
	return result
}

func (r *Registry) GetFor(name, version, platform, architecture, channel, currentVersion string) (Package, bool) {
	r.mu.RLock()
	item, ok := r.packages[name][version]
	if ok {
		item = clonePackage(item)
	}
	r.mu.RUnlock()
	if !ok || !releaseVisible(item, channel) {
		return Package{}, false
	}
	return SelectTarget(item, platform, architecture, currentVersion)
}

func (r *Registry) OpenPackageFor(name, version, platform, architecture, channel, currentVersion string) (*os.File, Package, error) {
	item, ok := r.GetFor(name, version, platform, architecture, channel, currentVersion)
	if !ok || len(item.Targets) == 0 {
		return nil, Package{}, os.ErrNotExist
	}
	target := item.Targets[0]
	packagePath := filepath.Join(r.root, name, version, "artifacts", target.ArtifactID, "package.bin")
	if target.ArtifactID == "legacy" {
		packagePath = filepath.Join(r.root, name, version, "package.bin")
	}
	file, err := os.Open(packagePath)
	if err != nil {
		return nil, Package{}, err
	}
	return file, item, nil
}

func (r *Registry) ListFor(platform, architecture, channel, currentVersion string) []Package {
	r.mu.RLock()
	names := make([]string, 0, len(r.packages))
	for name := range r.packages {
		names = append(names, name)
	}
	r.mu.RUnlock()
	sort.Strings(names)
	result := make([]Package, 0, len(names))
	for _, name := range names {
		if item, ok := r.LatestFor(name, platform, architecture, channel, currentVersion); ok {
			result = append(result, item)
		}
	}
	return result
}

func SelectTarget(item Package, platform, architecture, currentVersion string) (Package, bool) {
	if len(item.Targets) == 0 {
		return Package{}, false
	}
	platform = strings.TrimSpace(platform)
	architecture = strings.TrimSpace(architecture)
	if platform == "" && architecture == "" {
		selected := item.Targets[0]
		result := clonePackage(item)
		result.Targets = []Target{selected}
		applyTarget(&result, selected)
		return result, true
	}
	normalizedPlatform, err := scoutpkg.NormalizePlatform(platform)
	if err != nil {
		return Package{}, false
	}
	normalizedArchitecture, err := scoutpkg.NormalizeArchitecture(architecture)
	if err != nil {
		return Package{}, false
	}
	bestIndex := -1
	bestScore := 1000
	for index, target := range item.Targets {
		score, compatible := targetScore(target, normalizedPlatform, normalizedArchitecture, currentVersion)
		if compatible && score < bestScore {
			bestIndex = index
			bestScore = score
		}
	}
	if bestIndex < 0 {
		return Package{}, false
	}
	selected := item.Targets[bestIndex]
	result := clonePackage(item)
	result.Targets = []Target{selected}
	applyTarget(&result, selected)
	return result, true
}

func targetScore(target Target, platform, architecture, currentVersion string) (int, bool) {
	platformScore := -1
	switch {
	case target.Platform == platform && target.Architecture == architecture:
		platformScore = 0
	case target.Platform == platform && target.Architecture == "universal":
		platformScore = 10
	case target.Platform == "any" && target.Architecture == architecture:
		platformScore = 20
	case target.Platform == "any" && target.Architecture == "universal":
		platformScore = 30
	}
	if platformScore < 0 {
		return 0, false
	}
	if target.PackageType == "delta" {
		if currentVersion == "" || !containsVersion(target.UpgradeFrom, currentVersion) {
			return 0, false
		}
		return platformScore, true
	}
	return platformScore + 1, true
}

func normalizeRelease(item *Package) error {
	if err := ValidatePackage(item.Name, item.Version); err != nil {
		return err
	}
	item.Channel = strings.ToLower(strings.TrimSpace(item.Channel))
	if item.Channel == "" {
		item.Channel = "stable"
	}
	if !allowedChannels[item.Channel] {
		return errors.New("\u53d1\u5e03\u901a\u9053\u53ea\u80fd\u662f stable\u3001beta \u6216 dev")
	}
	item.Status = strings.ToLower(strings.TrimSpace(item.Status))
	if item.Status == "" {
		item.Status = "published"
	}
	if !allowedStatuses[item.Status] {
		return errors.New("\u53d1\u5e03\u72b6\u6001\u65e0\u6548")
	}
	item.PackageType = normalizePackageType(item.PackageType)
	if item.FileName != "" {
		item.FileName = filepath.Base(item.FileName)
		if err := ValidateFileName(item.FileName); err != nil {
			return err
		}
	}
	return nil
}

func normalizeTarget(target *Target, fallbackType string) error {
	platform := target.Platform
	if strings.TrimSpace(platform) == "" {
		platform = "any"
	}
	normalizedPlatform, err := scoutpkg.NormalizePlatform(platform)
	if err != nil {
		return err
	}
	architecture := target.Architecture
	if strings.TrimSpace(architecture) == "" {
		architecture = "universal"
	}
	normalizedArchitecture, err := scoutpkg.NormalizeArchitecture(architecture)
	if err != nil {
		return err
	}
	target.Platform = normalizedPlatform
	target.Architecture = normalizedArchitecture
	if target.PackageType == "" {
		target.PackageType = fallbackType
	}
	target.PackageType = normalizePackageType(target.PackageType)
	if target.PackageType == "delta" && len(target.UpgradeFrom) == 0 {
		return errors.New("\u5dee\u5206\u5305\u5fc5\u987b\u6307\u5b9a upgrade_from")
	}
	for _, version := range target.UpgradeFrom {
		if !versionPattern.MatchString(version) {
			return errors.New("upgrade_from \u5305\u542b\u65e0\u6548\u7248\u672c")
		}
	}
	target.FileName = filepath.Base(strings.TrimSpace(target.FileName))
	if err := ValidateFileName(target.FileName); err != nil {
		return err
	}
	target.ID = targetIdentity(*target)
	return nil
}

func normalizePackage(item *Package) {
	if item.Channel == "" {
		item.Channel = "stable"
	}
	if item.Status == "" {
		item.Status = "published"
	}
	if item.PackageType == "" {
		item.PackageType = "full"
	}
	for index := range item.Targets {
		if item.Targets[index].PackageType == "" {
			item.Targets[index].PackageType = item.PackageType
		}
	}
}

func normalizePackageType(value string) string {
	switch strings.ToLower(strings.TrimSpace(value)) {
	case "delta", "patch", "differential":
		return "delta"
	default:
		return "full"
	}
}

func targetIdentity(target Target) string {
	identity := target.Platform + "-" + target.Architecture + "-" + target.PackageType
	if target.PackageType == "delta" {
		versions := append([]string(nil), target.UpgradeFrom...)
		sort.Strings(versions)
		digest := sha256.Sum256([]byte(strings.Join(versions, ",")))
		identity += "-" + hex.EncodeToString(digest[:6])
	}
	return identity
}

func mergeReleaseMetadata(stored *Package, input Package) error {
	if stored.Channel != input.Channel {
		return errors.New("\u540c\u4e00\u7248\u672c\u4e0d\u80fd\u4f7f\u7528\u4e0d\u540c\u53d1\u5e03\u901a\u9053")
	}
	if stored.Status != input.Status {
		return errors.New("\u540c\u4e00\u7248\u672c\u4e0d\u80fd\u4f7f\u7528\u4e0d\u540c\u53d1\u5e03\u72b6\u6001")
	}
	if stored.Description == "" {
		stored.Description = input.Description
	}
	return nil
}

func writeTemporaryArtifact(versionDir string, data io.Reader) (string, int64, string, error) {
	temp, err := os.CreateTemp(versionDir, ".upload-*")
	if err != nil {
		return "", 0, "", fmt.Errorf("\u521b\u5efa\u4e34\u65f6\u6587\u4ef6\u5931\u8d25: %w", err)
	}
	tempPath := temp.Name()
	hash := sha256.New()
	size, copyErr := io.Copy(io.MultiWriter(temp, hash), data)
	closeErr := temp.Close()
	if copyErr != nil {
		return tempPath, 0, "", fmt.Errorf("\u5199\u5165\u5305\u6587\u4ef6\u5931\u8d25: %w", copyErr)
	}
	if closeErr != nil {
		return tempPath, 0, "", fmt.Errorf("\u5173\u95ed\u5305\u6587\u4ef6\u5931\u8d25: %w", closeErr)
	}
	if size == 0 {
		return tempPath, 0, "", errors.New("\u5305\u6587\u4ef6\u4e0d\u80fd\u4e3a\u7a7a")
	}
	return tempPath, size, hex.EncodeToString(hash.Sum(nil)), nil
}

func saveArtifact(artifactDir, tempPath string, metadata Target) error {
	if err := os.MkdirAll(artifactDir, 0o755); err != nil {
		return fmt.Errorf("\u521b\u5efa\u4ea7\u7269\u76ee\u5f55\u5931\u8d25: %w", err)
	}
	packagePath := filepath.Join(artifactDir, "package.bin")
	if err := os.Rename(tempPath, packagePath); err != nil {
		return fmt.Errorf("\u4fdd\u5b58\u4ea7\u7269\u6587\u4ef6\u5931\u8d25: %w", err)
	}
	data, err := json.MarshalIndent(metadata, "", "  ")
	if err != nil {
		return fmt.Errorf("\u7f16\u7801\u4ea7\u7269\u5143\u6570\u636e\u5931\u8d25: %w", err)
	}
	if err := os.WriteFile(filepath.Join(artifactDir, "metadata.json"), data, 0o644); err != nil {
		return fmt.Errorf("\u4fdd\u5b58\u4ea7\u7269\u5143\u6570\u636e\u5931\u8d25: %w", err)
	}
	return nil
}

func (r *Registry) persistRelease(item Package) error {
	data, err := json.MarshalIndent(item, "", "  ")
	if err != nil {
		return fmt.Errorf("\u7f16\u7801\u53d1\u5e03\u5143\u6570\u636e\u5931\u8d25: %w", err)
	}
	path := filepath.Join(r.root, item.Name, item.Version, "release.json")
	if err := os.WriteFile(path, data, 0o644); err != nil {
		return fmt.Errorf("\u4fdd\u5b58\u53d1\u5e03\u5143\u6570\u636e\u5931\u8d25: %w", err)
	}
	return nil
}

func (r *Registry) release(name, version string) Package {
	r.mu.RLock()
	defer r.mu.RUnlock()
	return clonePackage(r.packages[name][version])
}

func (r *Registry) storeRelease(item Package) {
	r.mu.Lock()
	defer r.mu.Unlock()
	if r.packages[item.Name] == nil {
		r.packages[item.Name] = make(map[string]Package)
	}
	r.packages[item.Name][item.Version] = clonePackage(item)
}

func (r *Registry) broadcast(item Package) {
	if item.Status != "published" {
		return
	}
	r.mu.RLock()
	subscribers := make([]chan Update, 0, len(r.subs))
	for _, subscriber := range r.subs {
		subscribers = append(subscribers, subscriber)
	}
	r.mu.RUnlock()
	update := Update{Package: item}
	for _, subscriber := range subscribers {
		select {
		case subscriber <- update:
		default:
		}
	}
}

func releaseVisible(item Package, channel string) bool {
	if item.Status != "published" {
		return false
	}
	channel = strings.ToLower(strings.TrimSpace(channel))
	return channel == "" || item.Channel == channel
}

func applyTarget(item *Package, target Target) {
	item.Platform = target.Platform
	item.Architecture = target.Architecture
	item.PackageType = target.PackageType
	item.FileName = target.FileName
	item.Size = target.Size
	item.SHA256 = target.SHA256
}

func clonePackage(item Package) Package {
	item.Targets = append([]Target(nil), item.Targets...)
	for index := range item.Targets {
		item.Targets[index].UpgradeFrom = append([]string(nil), item.Targets[index].UpgradeFrom...)
	}
	return item
}

func containsVersion(versions []string, wanted string) bool {
	for _, version := range versions {
		if version == wanted {
			return true
		}
	}
	return false
}

func (r *Registry) loadReleases() error {
	r.mu.Lock()
	for name, versions := range r.packages {
		for version, item := range versions {
			normalizePackage(&item)
			if len(item.Targets) == 0 {
				item.Targets = []Target{{
					ID:           "legacy",
					Platform:     "any",
					Architecture: "universal",
					PackageType:  "full",
					FileName:     item.FileName,
					Size:         item.Size,
					SHA256:       item.SHA256,
					ArtifactID:   "legacy",
				}}
			}
			versions[version] = item
		}
		r.packages[name] = versions
	}
	r.mu.Unlock()

	packages, err := os.ReadDir(r.root)
	if err != nil {
		return fmt.Errorf("\u8bfb\u53d6\u5b58\u50a8\u76ee\u5f55\u5931\u8d25: %w", err)
	}
	for _, packageEntry := range packages {
		if !packageEntry.IsDir() || !packageNamePattern.MatchString(packageEntry.Name()) {
			continue
		}
		versions, err := os.ReadDir(filepath.Join(r.root, packageEntry.Name()))
		if err != nil {
			return fmt.Errorf("\u8bfb\u53d6\u5305\u76ee\u5f55\u5931\u8d25: %w", err)
		}
		for _, versionEntry := range versions {
			if !versionEntry.IsDir() || !versionPattern.MatchString(versionEntry.Name()) {
				continue
			}
			data, err := os.ReadFile(filepath.Join(r.root, packageEntry.Name(), versionEntry.Name(), "release.json"))
			if err != nil {
				continue
			}
			var item Package
			if err := json.Unmarshal(data, &item); err != nil {
				return fmt.Errorf("\u8bfb\u53d6\u53d1\u5e03\u5143\u6570\u636e\u5931\u8d25: %w", err)
			}
			normalizePackage(&item)
			r.storeRelease(item)
		}
	}
	return nil
}