fix: collect and report errors during parsing and command processing

merge_srt.py

@@ -4,54 +4,85 @@ import json
 
 class SRTMerger:
     def __init__(self, srt1_filename, srt2_filename, commands_filename, output_filename):
-        self.srt1 = self.parse_srt(srt1_filename)
+        self.errors = []
-        self.srt2 = self.parse_srt(srt2_filename)
+        self.srt1, srt1_errors = self.parse_srt(srt1_filename)
-        self.commands = self.read_commands(commands_filename)
+        self.errors.extend(srt1_errors)
+        self.srt2, srt2_errors = self.parse_srt(srt2_filename)
+        self.errors.extend(srt2_errors)
+        self.commands, cmd_errors = self.read_commands(commands_filename)
+        self.errors.extend(cmd_errors)
         self.output = []
         self.output_filename = output_filename
 
     def parse_srt(self, filename):
-        with open(filename, 'r', encoding='utf-8-sig') as f:
-            content = f.read().strip()
-        blocks = content.split('\n\n')
         entries = []
-        for block in blocks:
+        errors = []
+        try:
+            with open(filename, 'r', encoding='utf-8-sig') as f:
+                content = f.read().strip()
+        except IOError as e:
+            errors.append(f"Error reading {filename}: {e}")
+            return entries, errors
+        blocks = content.split('\n\n')
+        for block_number, block in enumerate(blocks, start=1):
             lines = block.split('\n')
             if len(lines) < 3:
+                errors.append(f"Block {block_number} in {filename} has less than 3 lines.")
                 continue
-            timestamp = lines[1]
+            try:
-            text = '\n'.join(lines[2:]).strip()
+                timestamp_line = lines[1]
-            entries.append({
+                text = '\n'.join(lines[2:]).strip()
-                'timestamp': timestamp,
+                entries.append({
-                'text': text,
+                    'timestamp': timestamp_line,
-            })
+                    'text': text,
-        return entries
+                })
+            except Exception as e:
+                errors.append(f"Error parsing block {block_number} in {filename}: {e}")
+        return entries, errors
 
     def read_commands(self, filename):
-        with open(filename, 'r', encoding='utf-8') as f:
-            lines = f.readlines()
         commands = []
-        for line in lines:
+        errors = []
+        try:
+            with open(filename, 'r', encoding='utf-8') as f:
+                lines = f.readlines()
+        except IOError as e:
+            errors.append(f"Error reading {filename}: {e}")
+            return commands, errors
+        for line_number, line in enumerate(lines, start=1):
             line = line.strip()
-            if not line or line.startswith('#'):
+            if not line:
+                continue
+            if line.startswith('#'):
                 continue
             parts = shlex.split(line)
             if not parts:
+                errors.append(f"Line {line_number}: empty command after splitting.")
                 continue
             command = parts[0].upper()
+            if command not in ['COPY', 'MAP', 'SYNC', 'PUT']:
+                errors.append(f"Line {line_number}: unknown command '{command}'.")
+                continue
+            parsed = None
             if command == 'COPY':
                 parsed = self.parse_copy(parts)
+                if parsed is None:
+                    errors.append(f"Line {line_number}: invalid COPY command.")
             elif command == 'MAP':
                 parsed = self.parse_map(parts)
+                if parsed is None:
+                    errors.append(f"Line {line_number}: invalid MAP command.")
             elif command == 'SYNC':
                 parsed = self.parse_sync(parts)
+                if parsed is None:
+                    errors.append(f"Line {line_number}: invalid SYNC command.")
             elif command == 'PUT':
                 parsed = self.parse_put(parts)
-            else:
+                if parsed is None:
-                parsed = None
+                    errors.append(f"Line {line_number}: invalid PUT command.")
             if parsed is not None:
                 commands.append(parsed)
-        return commands
+        return commands, errors
 
     def parse_copy(self, parts):
         if len(parts) != 3:
@@ -114,7 +145,6 @@ class SRTMerger:
                 return None
             text = data['text']
         except (ValueError, json.JSONDecodeError, TypeError) as e:
-            print(f"Error parsing PUT command: {e}")
             return None
         return ('PUT', source, index, text)
 
@@ -128,13 +158,12 @@ class SRTMerger:
                 self.handle_sync(*cmd[1:])
             elif cmd[0] == 'PUT':
                 self.handle_put(*cmd[1:])
-        self.write_output()
 
     def handle_copy(self, source, start, end):
         source_list = self.srt1 if source == 1 else self.srt2
         start_idx, end_idx = start - 1, end - 1
         if start_idx < 0 or end_idx >= len(source_list) or start_idx > end_idx:
-            print(f"Skipping invalid COPY command: source {source}, range {start}-{end}")
+            self.errors.append(f"Invalid COPY command: source {source}, range {start}-{end}.")
             return
         self.output.extend(source_list[start_idx:end_idx + 1])
 
@@ -146,7 +175,7 @@ class SRTMerger:
         time_start_idx = time_start - 1
         if (text_start_idx < 0 or text_start_idx + count > len(text_list) or
             time_start_idx < 0 or time_start_idx + count > len(time_list)):
-            print(f"Skipping invalid MAP command: source {text_source}, text start {text_start}, time start {time_start}, count {count}")
+            self.errors.append(f"Invalid MAP command: source {text_source}, text start {text_start}, time start {time_start}, count {count}.")
             return
         for i in range(count):
             text_entry = text_list[text_start_idx + i]
@@ -164,7 +193,7 @@ class SRTMerger:
         prev_time_idx = time_start_idx - 1
         if (text_start_idx < 0 or text_start_idx >= len(text_list) or
             time_start_idx < 1 or prev_time_idx < 0 or time_start_idx >= len(time_list)):
-            print(f"Skipping invalid SYNC command: text index {text_index} must be >=1 and <= {len(text_list)}, time index {time_index} must be >=2 and <= {len(time_list)}")
+            self.errors.append(f"Invalid SYNC command: text index {text_index} must be >=1 and <= {len(text_list)}, time index {time_index} must be >=2 and <= {len(time_list)}.")
             return
         text_entry = text_list[text_start_idx]
         time_entry = time_list[time_start_idx]
@@ -180,7 +209,7 @@ class SRTMerger:
         source_list = self.srt1 if source == 1 else self.srt2
         index_idx = index - 1
         if index_idx < 0 or index_idx >= len(source_list):
-            print(f"Skipping invalid PUT command: source {source}, index {index} is out of bounds")
+            self.errors.append(f"Invalid PUT command: source {source}, index {index} is out of bounds.")
             return
         entry = source_list[index_idx]
         new_entry = {
@@ -193,8 +222,11 @@ class SRTMerger:
         if self.output_filename == '-':
             out = sys.stdout
         else:
-            out = open(self.output_filename, 'w', encoding='utf-8')
+            try:
-
+                out = open(self.output_filename, 'w', encoding='utf-8')
+            except IOError as e:
+                print(f"Error writing to {self.output_filename}: {e}", file=sys.stderr)
+                return
         try:
             for i, entry in enumerate(self.output, start=1):
                 out.write(f"{i}\n{entry['timestamp']}\n{entry['text'].strip()}\n\n")
@@ -245,8 +277,17 @@ class SRTMerger:
 
 if __name__ == '__main__':
     if len(sys.argv) != 5:
-        print("Usage: python merge_srt.py <srt1> <srt2> <commands> <output>")
+        print("Usage: python merge_srt.py <srt1> <srt2> <commands> <output>", file=sys.stderr)
         sys.exit(1)
     srt1_filename, srt2_filename, commands_filename, output_filename = sys.argv[1:5]
     merger = SRTMerger(srt1_filename, srt2_filename, commands_filename, output_filename)
+    if merger.errors:
+        for error in merger.errors:
+            print(error, file=sys.stderr)
+        sys.exit(1)
     merger.process_commands()
+    if merger.errors:
+        for error in merger.errors:
+            print(error, file=sys.stderr)
+        sys.exit(1)
+    merger.write_output()