package storage

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

	"expo-updates-server-go/internal/model"
)

var ErrUnsupportedRuntime = errors.New("Unsupported runtime version")
var ErrUnsupportedPlatform = errors.New("Unsupported platform")

type LocalStore struct {
	root string
}

func NewLocalStore(root string) *LocalStore {
	return &LocalStore{root: root}
}

func (s *LocalStore) UpdatesRoot() string {
	return s.root
}

func (s *LocalStore) LatestReleasePath(runtimeVersion string, platform string) (string, error) {
	if platform != "ios" && platform != "android" {
		return "", ErrUnsupportedPlatform
	}
	runtimeDir := filepath.Join(s.root, runtimeVersion)
	runtimeStat, err := os.Stat(runtimeDir)
	if err != nil || !runtimeStat.IsDir() {
		return "", ErrUnsupportedRuntime
	}
	platformDir := filepath.Join(runtimeDir, platform)
	platformStat, err := os.Stat(platformDir)
	if err != nil || !platformStat.IsDir() {
		return "", ErrUnsupportedPlatform
	}
	return platformDir, nil
}

func (s *LocalStore) HasRollbackMarker(releasePath string) bool {
	_, err := os.Stat(filepath.Join(releasePath, "rollback"))
	return err == nil
}

func (s *LocalStore) ReadMetadata(releasePath string) (model.MetadataFile, []byte, time.Time, error) {
	var out model.MetadataFile
	metaPath := filepath.Join(releasePath, "metadata.json")
	b, err := os.ReadFile(metaPath)
	if err != nil {
		return out, nil, time.Time{}, err
	}
	if err := json.Unmarshal(b, &out); err != nil {
		return out, nil, time.Time{}, err
	}
	fi, err := os.Stat(metaPath)
	if err != nil {
		return out, nil, time.Time{}, err
	}
	return out, b, fi.ModTime(), nil
}

func (s *LocalStore) ReadExpoConfig(releasePath string) (map[string]any, error) {
	filePath := filepath.Join(releasePath, "expoConfig.json")
	b, err := os.ReadFile(filePath)
	if err != nil {
		return nil, err
	}
	var out map[string]any
	if err := json.Unmarshal(b, &out); err != nil {
		return nil, err
	}
	return out, nil
}

func (s *LocalStore) OpenAssetSafe(asset string) ([]byte, error) {
	clean := filepath.Clean(asset)
	if strings.HasPrefix(clean, "..") {
		return nil, fmt.Errorf("invalid asset path")
	}
	return os.ReadFile(clean)
}

func (s *LocalStore) PublishZip(runtimeVersion string, platform string, zipReader io.ReaderAt, size int64) (string, error) {
	if platform != "ios" && platform != "android" {
		return "", fmt.Errorf("%w: %s", ErrUnsupportedPlatform, platform)
	}
	runtimeDir := filepath.Join(s.root, runtimeVersion)
	if err := os.MkdirAll(runtimeDir, 0o755); err != nil {
		return "", err
	}

	targetDir := filepath.Join(runtimeDir, platform)
	tmpDir := targetDir + ".tmp"
	_ = os.RemoveAll(tmpDir)
	_ = os.RemoveAll(targetDir)

	if err := unzipToDir(zipReader, size, tmpDir); err != nil {
		return "", err
	}

	manifestPath := filepath.Join(tmpDir, "metadata.json")
	if _, err := os.Stat(manifestPath); err != nil {
		return "", fmt.Errorf("published zip must contain metadata.json at root")
	}

	if err := os.Rename(tmpDir, targetDir); err != nil {
		return "", err
	}
	return targetDir, nil
}

func (s *LocalStore) CreateRollback(runtimeVersion string, platform string) (string, error) {
	if platform != "ios" && platform != "android" {
		return "", fmt.Errorf("%w: %s", ErrUnsupportedPlatform, platform)
	}
	releaseDir := filepath.Join(s.root, runtimeVersion, platform)
	if _, err := os.Stat(releaseDir); err != nil {
		return "", err
	}
	path := filepath.Join(releaseDir, "rollback")
	if err := os.WriteFile(path, []byte{}, 0o644); err != nil {
		return "", err
	}
	return path, nil
}

func (s *LocalStore) ListReleases(runtimeVersion string) ([]model.ReleaseInfo, error) {
	runtimeDir := filepath.Join(s.root, runtimeVersion)
	runtimeStat, err := os.Stat(runtimeDir)
	if err != nil || !runtimeStat.IsDir() {
		return nil, ErrUnsupportedRuntime
	}
	entries, err := os.ReadDir(runtimeDir)
	if err != nil {
		return nil, err
	}
	out := make([]model.ReleaseInfo, 0, len(entries))
	for _, e := range entries {
		if !e.IsDir() {
			continue
		}
		if e.Name() != "ios" && e.Name() != "android" {
			continue
		}
		full := filepath.Join(runtimeDir, e.Name())
		fi, err := os.Stat(full)
		if err != nil {
			continue
		}
		out = append(out, model.ReleaseInfo{
			RuntimeVersion: runtimeVersion,
			ReleaseID:      e.Name(),
			Path:           full,
			CreatedAt:      fi.ModTime(),
		})
	}
	sort.Slice(out, func(i, j int) bool { return out[i].ReleaseID < out[j].ReleaseID })
	return out, nil
}