"""
Structured logging configuration using structlog.

Produces JSON logs in production and human-readable output in development.
Every log line carries a request_id for traceability.
"""

import logging
import sys
import uuid

import structlog
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.requests import Request

from app.core.config import get_settings


def setup_logging() -> None:
    """Configure structlog processors and stdlib integration."""
    settings = get_settings()

    shared_processors: list = [
        structlog.contextvars.merge_contextvars,
        structlog.stdlib.add_log_level,
        structlog.stdlib.add_logger_name,
        structlog.processors.TimeStamper(fmt="iso"),
        structlog.processors.StackInfoRenderer(),
        structlog.processors.format_exc_info,
    ]

    if settings.app_env == "development":
        renderer = structlog.dev.ConsoleRenderer()
    else:
        renderer = structlog.processors.JSONRenderer()

    structlog.configure(
        processors=[
            *shared_processors,
            structlog.stdlib.ProcessorFormatter.wrap_for_formatter,
        ],
        logger_factory=structlog.stdlib.LoggerFactory(),
        wrapper_class=structlog.stdlib.BoundLogger,
        cache_logger_on_first_use=True,
    )

    formatter = structlog.stdlib.ProcessorFormatter(
        processors=[
            structlog.stdlib.ProcessorFormatter.remove_processors_meta,
            renderer,
        ],
    )

    handler = logging.StreamHandler(sys.stdout)
    handler.setFormatter(formatter)

    root_logger = logging.getLogger()
    root_logger.handlers.clear()
    root_logger.addHandler(handler)
    root_logger.setLevel(getattr(logging, settings.log_level.upper(), logging.INFO))


def get_logger(name: str = __name__):
    """Return a bound structlog logger."""
    return structlog.get_logger(name)


class RequestIdMiddleware(BaseHTTPMiddleware):
    """
    Injects a unique request_id into every request lifecycle.

    The ID is returned in the X-Request-Id response header and bound
    to structlog's context variables for the duration of the request.
    """

    async def dispatch(self, request: Request, call_next):
        request_id = request.headers.get("X-Request-Id", str(uuid.uuid4()))
        structlog.contextvars.clear_contextvars()
        structlog.contextvars.bind_contextvars(request_id=request_id)

        response = await call_next(request)
        response.headers["X-Request-Id"] = request_id
        return response