from __future__ import annotations

import json
import logging
import os
import sys
from datetime import datetime, timezone
from typing import Any

LOG_FIELDS = (
    "event",
    "request_id",
    "segment_id",
    "feedback_session_id",
    "status",
    "latency_ms",
    "audio_size_bytes",
    "audio_duration_ms",
    "audio_format",
    "error_class",
)


class JsonFormatter(logging.Formatter):
    def format(self, record: logging.LogRecord) -> str:
        payload: dict[str, Any] = {
            "timestamp": datetime.now(timezone.utc).isoformat(timespec="milliseconds"),
            "level": record.levelname,
            "service": "funasr",
            "environment": os.getenv("APP_ENV", "development"),
            "app_version": os.getenv("APP_VERSION", "unknown"),
            "git_sha": os.getenv("GIT_SHA", "unknown"),
            "message": record.getMessage(),
        }
        for field in LOG_FIELDS:
            value = getattr(record, field, None)
            if value is not None:
                payload[field] = value
        return json.dumps(payload, ensure_ascii=False, default=str)


class JsonLogStream:
    encoding = "utf-8"

    def __init__(self, level: int) -> None:
        self.level = level
        self.buffer = ""

    def write(self, message: str) -> int:
        self.buffer += message
        while "\n" in self.buffer:
            line, self.buffer = self.buffer.split("\n", 1)
            self._emit(line)
        return len(message)

    def flush(self) -> None:
        if self.buffer:
            self._emit(self.buffer)
            self.buffer = ""

    def isatty(self) -> bool:
        return False

    def _emit(self, message: str) -> None:
        message = message.strip()
        if message:
            logging.getLogger("funasr-service").log(self.level, message)


def configure_logging() -> None:
    handler = logging.StreamHandler(sys.__stdout__)
    handler.setFormatter(JsonFormatter())
    root = logging.getLogger()
    root.handlers.clear()
    root.addHandler(handler)
    root.setLevel(logging.INFO)

    for name, logger in logging.Logger.manager.loggerDict.items():
        if isinstance(logger, logging.Logger):
            logger.handlers.clear()
            logger.propagate = name != "uvicorn.access"


def redirect_standard_streams() -> None:
    sys.stdout = JsonLogStream(logging.INFO)  # type: ignore[assignment]
    sys.stderr = JsonLogStream(logging.ERROR)  # type: ignore[assignment]


def log_event(level: int, event: str, message: str, **fields: Any) -> None:
    logging.getLogger("funasr-service").log(level, message, extra={"event": event, **fields})