package services

import (
	"archive/tar"
	"compress/gzip"
	"context"
	"fmt"
	"io"
	"path"
	"strings"
	"time"

	"fwh-toolbox-server/cache"
	minioRepo "fwh-toolbox-server/repositories/minio"
	mongoRepo "fwh-toolbox-server/repositories/mongo"
)

type DataDownloadArchiveEntry struct {
	Path      string `json:"path"`
	Size      int64  `json:"size"`
	Directory bool   `json:"directory"`
}

func ListDataDownloadArchive(ctx context.Context, documentID string) ([]DataDownloadArchiveEntry, error) {
	lock, err := cache.Lock(ctx, "data-download:content:"+documentID, 10*time.Minute, 100*time.Millisecond, 10*time.Second)
	if err != nil {
		return nil, err
	}
	defer lock.SafeRelease(context.Background())
	reader, compressed, archive, err := openDataDownloadTarGz(ctx, documentID)
	if err != nil {
		return nil, err
	}
	defer reader.Close()
	defer compressed.Close()
	var entries []DataDownloadArchiveEntry
	for {
		header, err := archive.Next()
		if err == io.EOF {
			break
		}
		if err != nil {
			return nil, err
		}
		clean, err := safeArchiveEntry(header.Name)
		if err != nil {
			continue
		}
		entries = append(entries, DataDownloadArchiveEntry{Path: clean, Size: header.Size, Directory: header.FileInfo().IsDir()})
	}
	return entries, nil
}

func ReadDataDownloadArchiveEntry(ctx context.Context, documentID, entryPath string) ([]byte, error) {
	lock, err := cache.Lock(ctx, "data-download:content:"+documentID, 10*time.Minute, 100*time.Millisecond, 10*time.Second)
	if err != nil {
		return nil, err
	}
	defer lock.SafeRelease(context.Background())
	wanted, err := safeArchiveEntry(entryPath)
	if err != nil {
		return nil, err
	}
	reader, compressed, archive, err := openDataDownloadTarGz(ctx, documentID)
	if err != nil {
		return nil, err
	}
	defer reader.Close()
	defer compressed.Close()
	for {
		header, err := archive.Next()
		if err == io.EOF {
			return nil, fmt.Errorf("archive entry not found")
		}
		if err != nil {
			return nil, err
		}
		clean, cleanErr := safeArchiveEntry(header.Name)
		if cleanErr != nil || clean != wanted || header.FileInfo().IsDir() {
			continue
		}
		return io.ReadAll(io.LimitReader(archive, header.Size))
	}
}

func openDataDownloadTarGz(ctx context.Context, documentID string) (io.ReadCloser, *gzip.Reader, *tar.Reader, error) {
	document, err := mongoRepo.GetDataDownloadDocument(ctx, documentID)
	if err != nil {
		return nil, nil, nil, err
	}
	if document.BinaryObjectKey == "" || !(strings.HasSuffix(strings.ToLower(document.BinaryObjectKey), ".tar.gz") || strings.HasSuffix(strings.ToLower(document.BinaryObjectKey), ".tgz")) {
		return nil, nil, nil, fmt.Errorf("document is not a tar.gz archive")
	}
	reader, err := minioRepo.Open(ctx, document.BinaryObjectKey)
	if err != nil {
		return nil, nil, nil, err
	}
	gz, err := gzip.NewReader(reader)
	if err != nil {
		_ = reader.Close()
		return nil, nil, nil, err
	}
	return reader, gz, tar.NewReader(gz), nil
}

func safeArchiveEntry(value string) (string, error) {
	clean := strings.TrimPrefix(path.Clean("/"+strings.ReplaceAll(value, "\\", "/")), "/")
	if clean == "." || clean == "" || strings.HasPrefix(clean, "../") {
		return "", fmt.Errorf("invalid archive entry")
	}
	return clean, nil
}