From 0a3babb2e75d08d764bbe22ebfba787fd0da7c6e Mon Sep 17 00:00:00 2001
From: Jamie Mansfield <jmansfield@cadixdev.org>
Date: Mon, 11 May 2020 13:09:42 +0100
Subject: [PATCH] Remove unmodified files that have been removed from the pack

---
 ftbinstall/installer.go       | 78 +++++++++++++++++++++++++++++++++++
 ftbinstall/installer_files.go |  1 -
 2 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/ftbinstall/installer.go b/ftbinstall/installer.go
index 3c9db78..90f911d 100644
--- a/ftbinstall/installer.go
+++ b/ftbinstall/installer.go
@@ -6,7 +6,9 @@ package ftbinstall
 
 import (
 	"bytes"
+	"crypto/sha1"
 	"encoding/base64"
+	"encoding/hex"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -14,10 +16,12 @@ import (
 	"github.com/jamiemansfield/ftbinstall/mcinstall"
 	"github.com/jamiemansfield/ftbinstall/util"
 	"github.com/jamiemansfield/go-ftbmeta/ftbmeta"
+	"io"
 	"io/ioutil"
 	"net/http"
 	"os"
 	"path/filepath"
+	"strings"
 )
 
 const (
@@ -25,6 +29,13 @@ const (
 	SettingsFile = "install.json"
 )
 
+var (
+	ExcludedDirs = []string{
+		DataDir,
+		"saves",
+	}
+)
+
 var (
 	OtherPackAlreadyInstalled = errors.New("ftbinstall: a pack is already installed at this location")
 )
@@ -73,6 +84,73 @@ func InstallPackVersion(installTarget mcinstall.InstallTarget, dest string, pack
 		return err
 	}
 
+	// Remove any unmodified files that are no longer apart the pack
+	err = filepath.Walk(destination, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if info.IsDir() {
+			return nil
+		}
+
+		relPath, err := filepath.Rel(destination, path)
+		if err != nil {
+			return err
+		}
+		ftbPath := "./" + filepath.ToSlash(relPath)
+
+		// While this should never be an issue anyway - for peace of mind,
+		// ftbinstall will not delete ANYTHING from a protected directory.
+		parts := strings.Split(relPath, string(filepath.Separator))
+		for _, excludedDir := range ExcludedDirs {
+			if parts[0] == excludedDir {
+				return nil
+			}
+		}
+
+		// Ignore if its a current file
+		if install.NewFiles[ftbPath] != "" {
+			return nil
+		}
+
+		// Check if its been modified
+		if install.OriginalFiles[ftbPath] != "" {
+			f, err := os.Open(path)
+			if err != nil {
+				return err
+			}
+			defer f.Close()
+
+			hasher := sha1.New()
+			if _, err := io.Copy(hasher, f); err != nil {
+				return err
+			}
+			hash := hex.EncodeToString(hasher.Sum(nil))
+
+			// Delete file
+			if hash == install.OriginalFiles[ftbPath] {
+				fmt.Printf("%s has been removed from the modpack, as its\n", ftbPath)
+				fmt.Println("sha1 hash matches the original, it has been removed.")
+				return os.Remove(path)
+			}
+
+			// The file has been removed from the pack, but the player has modified it
+			fmt.Printf("%s has been removed from the modpack, as its\n", ftbPath)
+			fmt.Println("sha1 hash doesn't match the original - we have left it in place.")
+			fmt.Println("Please investigate whether you still need the file before playing!")
+			fmt.Printf("You can remove the '%s' line from %s/%s if\n", ftbPath, DataDir, SettingsFile)
+			fmt.Println("still required")
+
+			// So that this message continues on, store the original hash in the new file list
+			install.NewFiles[ftbPath] = install.OriginalFiles[ftbPath]
+		}
+
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+
 	// Install profile for the Minecraft launcher
 	if installTarget == mcinstall.Client {
 		// Get the target Minecraft version for the pack
diff --git a/ftbinstall/installer_files.go b/ftbinstall/installer_files.go
index d19d4b1..accd90f 100644
--- a/ftbinstall/installer_files.go
+++ b/ftbinstall/installer_files.go
@@ -65,7 +65,6 @@ func installFile(install *Install, dest string, file *ftbmeta.File) (string, err
 		if _, err := io.Copy(hasher, f); err != nil {
 			return "", err
 		}
-
 		hash := hex.EncodeToString(hasher.Sum(nil))
 
 		// If already exists, continue to next file