From 85878f69d30651a92052f35dff2a5848f6898b3b Mon Sep 17 00:00:00 2001
From: Maxim Slipenko <no-reply@maxim.slipenko.com>
Date: Fri, 20 Jun 2025 20:12:43 +0300
Subject: [PATCH] feat: add checksum for torrent downloader

---
 assets/coverage-badge.svg |  4 +--
 pkg/dl/git.go             | 31 ++--------------
 pkg/dl/torrent.go         | 12 ++++++-
 pkg/dl/utils.go           | 74 ++++++++++++++++++++++++++++++---------
 4 files changed, 72 insertions(+), 49 deletions(-)

diff --git a/assets/coverage-badge.svg b/assets/coverage-badge.svg
index 665bcb6..ff1ebbf 100644
--- a/assets/coverage-badge.svg
+++ b/assets/coverage-badge.svg
@@ -11,7 +11,7 @@
     <g fill="#fff" text-anchor="middle" font-family="DejaVu Sans,Verdana,Geneva,sans-serif" font-size="11">
         <text x="33.5" y="15" fill="#010101" fill-opacity=".3">coverage</text>
         <text x="33.5" y="14">coverage</text>
-        <text x="86" y="15" fill="#010101" fill-opacity=".3">20.2%</text>
-        <text x="86" y="14">20.2%</text>
+        <text x="86" y="15" fill="#010101" fill-opacity=".3">20.1%</text>
+        <text x="86" y="14">20.1%</text>
     </g>
 </svg>
diff --git a/pkg/dl/git.go b/pkg/dl/git.go
index 0de751f..b5380b1 100644
--- a/pkg/dl/git.go
+++ b/pkg/dl/git.go
@@ -20,11 +20,8 @@
 package dl
 
 import (
-	"bytes"
 	"context"
-	"encoding/hex"
 	"errors"
-	"log/slog"
 	"net/url"
 	"path"
 	"strconv"
@@ -127,7 +124,7 @@ func (d *GitDownloader) Download(ctx context.Context, opts Options) (Type, strin
 		}
 	}
 
-	err = d.verifyHash(opts)
+	err = VerifyHashFromLocal("", opts)
 	if err != nil {
 		return 0, "", err
 	}
@@ -139,30 +136,6 @@ func (d *GitDownloader) Download(ctx context.Context, opts Options) (Type, strin
 	return TypeDir, name, nil
 }
 
-func (GitDownloader) verifyHash(opts Options) error {
-	if opts.Hash != nil {
-		h, err := opts.NewHash()
-		if err != nil {
-			return err
-		}
-
-		err = HashDir(opts.Destination, h)
-		if err != nil {
-			return err
-		}
-
-		sum := h.Sum(nil)
-
-		slog.Warn("validate checksum", "real", hex.EncodeToString(sum), "expected", hex.EncodeToString(opts.Hash))
-
-		if !bytes.Equal(sum, opts.Hash) {
-			return ErrChecksumMismatch
-		}
-	}
-
-	return nil
-}
-
 // Update uses git to pull the repository and update it
 // to the latest revision. It allows specifying the depth
 // and recursion options via query string. It returns
@@ -225,7 +198,7 @@ func (d *GitDownloader) Update(opts Options) (bool, error) {
 		return false, err
 	}
 
-	err = d.verifyHash(opts)
+	err = VerifyHashFromLocal("", opts)
 	if err != nil {
 		return false, err
 	}
diff --git a/pkg/dl/torrent.go b/pkg/dl/torrent.go
index 31a2a62..42427f0 100644
--- a/pkg/dl/torrent.go
+++ b/pkg/dl/torrent.go
@@ -71,7 +71,17 @@ func (TorrentDownloader) Download(ctx context.Context, opts Options) (Type, stri
 		return 0, "", err
 	}
 
-	return determineType(opts.Destination)
+	dlType, name, err := determineType(opts.Destination)
+	if err != nil {
+		return 0, "", err
+	}
+
+	err = VerifyHashFromLocal(name, opts)
+	if err != nil {
+		return 0, "", err
+	}
+
+	return dlType, name, nil
 }
 
 func removeTorrentFiles(path string) error {
diff --git a/pkg/dl/utils.go b/pkg/dl/utils.go
index a4e4a62..a4fc8f1 100644
--- a/pkg/dl/utils.go
+++ b/pkg/dl/utils.go
@@ -17,39 +17,79 @@
 package dl
 
 import (
+	"bytes"
+	"encoding/hex"
+	"fmt"
 	"hash"
 	"io"
+	"log/slog"
 	"os"
 	"path/filepath"
 )
 
-func HashDir(dirPath string, h hash.Hash) error {
-	err := filepath.Walk(dirPath, func(path string, info os.FileInfo, err error) error {
+// If the checksum does not match, returns ErrChecksumMismatch
+func VerifyHashFromLocal(path string, opts Options) error {
+	if opts.Hash != nil {
+		h, err := opts.NewHash()
 		if err != nil {
 			return err
 		}
-		// Skip .git directory
-		if info.IsDir() && info.Name() == ".git" {
-			return filepath.SkipDir
+
+		err = HashLocal(filepath.Join(opts.Destination, path), h)
+		if err != nil {
+			return err
 		}
-		// Skip directories (only process files)
-		if !info.Mode().IsRegular() {
-			return nil
+
+		sum := h.Sum(nil)
+
+		slog.Debug("validate checksum", "real", hex.EncodeToString(sum), "expected", hex.EncodeToString(opts.Hash))
+
+		if !bytes.Equal(sum, opts.Hash) {
+			return ErrChecksumMismatch
 		}
-		// Open file
+	}
+
+	return nil
+}
+
+func HashLocal(path string, h hash.Hash) error {
+	info, err := os.Stat(path)
+	if err != nil {
+		return err
+	}
+
+	if info.Mode().IsRegular() {
+		// Single file
 		f, err := os.Open(path)
 		if err != nil {
 			return err
 		}
 		defer f.Close()
-		// Write file content to hasher
-		if _, err := io.Copy(h, f); err != nil {
-			return err
-		}
-		return nil
-	})
-	if err != nil {
+		_, err = io.Copy(h, f)
 		return err
 	}
-	return nil
+
+	if info.IsDir() {
+		// Walk directory
+		return filepath.Walk(path, func(path string, info os.FileInfo, err error) error {
+			if err != nil {
+				return err
+			}
+			if info.IsDir() && info.Name() == ".git" {
+				return filepath.SkipDir
+			}
+			if !info.Mode().IsRegular() {
+				return nil
+			}
+			f, err := os.Open(path)
+			if err != nil {
+				return err
+			}
+			defer f.Close()
+			_, err = io.Copy(h, f)
+			return err
+		})
+	}
+
+	return fmt.Errorf("unsupported file type: %s", path)
 }