"""Parser for mypy JSON output."""
import json
import logging
import structlog
from mcp_code_checker.code_checker_mypy.models import MypyMessage
logger = logging.getLogger(__name__)
structured_logger = structlog.get_logger(__name__)
def parse_mypy_json_output(output: str) -> tuple[list[MypyMessage], str | None]:
"""
Parse mypy JSON output into MypyMessage objects.
Mypy outputs one JSON object per line when using --output json.
Args:
output: Raw output from mypy command
Returns:
Tuple of (messages list, error string if parsing failed)
"""
messages = []
parse_errors = []
for line_num, line in enumerate(output.splitlines(), 1):
line = line.strip()
if not line:
continue
try:
data = json.loads(line)
# Extract fields with defaults
message = MypyMessage(
file=data.get("file", ""),
line=data.get("line", 0),
column=data.get("column", 0),
severity=data.get("severity", "error"),
message=data.get("message", ""),
code=data.get("code"),
)
messages.append(message)
except json.JSONDecodeError:
# Some lines might not be JSON (like summary text)
structured_logger.debug(
"Non-JSON line in mypy output", line_num=line_num, content=line[:100]
)
except (KeyError, TypeError, ValueError) as e:
parse_errors.append(f"Line {line_num}: {str(e)}")
if parse_errors and not messages:
error_msg = f"Failed to parse mypy output: {'; '.join(parse_errors)}"
return [], error_msg
structured_logger.info(
"Parsed mypy output",
total_messages=len(messages),
severities=list({msg.severity for msg in messages}),
)
return messages, None
