From 6be0543fc16b9c5c019aac9bb256cd8ea7772f67 Mon Sep 17 00:00:00 2001
From: Esteban Papp <81431996+amznestebanpapp@users.noreply.github.com>
Date: Mon, 8 Nov 2021 14:02:26 -0800
Subject: [PATCH] Adds script to brute-force detect unused files

Signed-off-by: Esteban Papp <81431996+amznestebanpapp@users.noreply.github.com>
---
 scripts/cleanup/unusued_compilation.py | 102 +++++++++++++++++++++++++
 1 file changed, 102 insertions(+)
 create mode 100644 scripts/cleanup/unusued_compilation.py

diff --git a/scripts/cleanup/unusued_compilation.py b/scripts/cleanup/unusued_compilation.py
new file mode 100644
index 0000000000..25fa4ca3ce
--- /dev/null
+++ b/scripts/cleanup/unusued_compilation.py
@@ -0,0 +1,102 @@
+#
+# Copyright (c) Contributors to the Open 3D Engine Project.
+# For complete copyright and license terms please see the LICENSE at the root of this distribution.
+#
+# SPDX-License-Identifier: Apache-2.0 OR MIT
+#
+#
+
+import argparse
+import os
+import shutil
+import sys
+sys.path.append(os.path.join(os.path.dirname(os.path.abspath(__file__)), '../build'))
+import ci_build
+
+EXTENSIONS_OF_INTEREST = ('.c', '.cc', '.cpp', '.cxx', '.h', '.hpp', '.hxx', '.inl')
+EXCLUSIONS = ('AZ_DECLARE_MODULE_CLASS')
+
+def create_filelist(path):
+    filelist = set()
+    for input_file in path:
+        if os.path.isdir(input_file):
+            for dp, dn, filenames in os.walk(input_file):
+                if 'build\\windows_vs2019' in dp:
+                    continue
+                for f in filenames:
+                    extension = os.path.splitext(f)[1]
+                    extension_lower = extension.lower()
+                    if extension_lower in EXTENSIONS_OF_INTEREST:
+                        filelist.add(os.path.join(dp, f))
+        else:
+            extension = os.path.splitext(input_file)[1]
+            extension_lower = extension.lower()
+            if extension_lower in EXTENSIONS_OF_INTEREST:
+                filelist.add(os.path.join(os.getcwd(), input_file))
+            else:
+                print(f'Error, file {input_file} does not have an extension of interest')
+                sys.exit(1)
+    return filelist
+
+def is_excluded(file):
+    normalized_file = os.path.normpath(file)
+    if '\\Platform\\' in normalized_file and not '\\Windows\\' in normalized_file:
+        return True
+    return False
+
+def filter_from_processed(filelist, filter_file_path):
+    if not os.path.exists(filter_file_path):
+        return # nothing to filter
+    
+    with open(filter_file_path, 'r') as filter_file:
+        try:
+            processed_files = [s.strip() for s in filter_file.readlines()]
+        except UnicodeDecodeError as err:
+            print('Error reading file {}, err: {}'.format(filter_file_path, err))
+            sys.exit(1)
+    filelist -= set(processed_files)
+    filelist = [f for f in filelist if not is_excluded(f)]
+
+def cleanup_unused_compilation(path):
+    # 1. Create a list of all h/cpp files (consider multiple extensions)
+    filelist = create_filelist(path)
+    # 2. Remove files from "processed" list. This is needed because the process is a bruteforce approach and
+    #    can take a while. If something is found in the middle, we want to be able to continue instead of 
+    #    starting over. Removing the "unusued_compilation_processed.txt" will start over.
+    filter_file_path = os.path.join(os.getcwd(), 'unusued_compilation_processed.txt')
+    filter_from_processed(filelist, filter_file_path)
+    # 3. For each file
+    total_files = len(filelist)
+    current_files = 1
+    for file in filelist:
+        print(f"[{current_files}/{total_files}] Trying {file}")
+        #   b. create backup
+        shutil.copy(file, file + '.bak')
+        #   c. set the file contents as empty
+        with open(file, 'w') as source_file:
+            source_file.write('')
+        #   d. build
+        ret = ci_build.build('build_config.json', 'Windows', 'profile_vs2019')
+        #     e.1 if build succeeds, leave the file empty (leave backup)
+        #     e.2 if build fails, restore backup
+        if ret != 0:
+            shutil.copy(file + '.bak', file)
+            print(f"\t[FAILED] restoring")
+        else:
+            print(f"\t[SUCCEED]")
+        #   f. delete backup
+        os.remove(file + '.bak')
+        #   add file to processed-list
+        with open(filter_file_path, 'a') as filter_file:
+            filter_file.write(file)
+            filter_file.write('\n')
+        current_files += 1
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description='This script finds C++ files that do not affect compilation (and therefore can be potentially removed)',
+        formatter_class=argparse.RawTextHelpFormatter)
+    parser.add_argument('file_or_dir', type=str, nargs='+', default=os.getcwd(),
+        help='list of files or directories to search within for files to consider')
+    args = parser.parse_args()
+    ret = cleanup_unused_compilation(args.file_or_dir)
+    sys.exit(ret)