from __future__ import annotations

import time
from typing import List, Optional

from fastapi import APIRouter, File, HTTPException, UploadFile
from pydantic import BaseModel, Field

from app.config import get_settings
from app.core.logger import get_logger
from app.services.qr_decoder_service import QRDecoderService

logger = get_logger(__name__)

router = APIRouter()

_settings = get_settings()
MAX_UPLOAD_BYTES = _settings.max_upload_bytes

_service = QRDecoderService(max_file_size_mb=_settings.max_upload_mb)


class QRDecodeUrlRequest(BaseModel):
    url: str = Field(
        ...,
        description="Public URL of the QR code image to decode",
    )


class DecodedQR(BaseModel):
    data: str
    type: str = "QRCODE"
    bounding_box: Optional[List[List[float]]] = None
    decoder: Optional[str] = None


class QRDecodeResponse(BaseModel):
    success: bool
    time_ms: float
    decoded: List[DecodedQR]
    count: int
    error_message: Optional[str] = None


@router.post(
    "/qr-decode/file",
    response_model=QRDecodeResponse,
    summary="Decode QR code from an uploaded image file",
    description="Upload an image file containing a QR code and get its decoded content.",
)
async def decode_qr_file(
    file: UploadFile = File(..., description="Image file containing a QR code"),
) -> QRDecodeResponse:
    start = time.perf_counter()

    if not file.content_type or not file.content_type.startswith("image/"):
        elapsed = round((time.perf_counter() - start) * 1000, 3)
        raise HTTPException(
            status_code=400,
            detail=QRDecodeResponse(
                success=False, time_ms=elapsed, decoded=[], count=0,
                error_message="Uploaded file must be an image.",
            ).model_dump(),
        )

    raw = await file.read()
    if len(raw) == 0:
        elapsed = round((time.perf_counter() - start) * 1000, 3)
        raise HTTPException(
            status_code=400,
            detail=QRDecodeResponse(
                success=False, time_ms=elapsed, decoded=[], count=0,
                error_message="Uploaded file is empty.",
            ).model_dump(),
        )
    if len(raw) > MAX_UPLOAD_BYTES:
        elapsed = round((time.perf_counter() - start) * 1000, 3)
        raise HTTPException(
            status_code=413,
            detail=QRDecodeResponse(
                success=False, time_ms=elapsed, decoded=[], count=0,
                error_message=f"File exceeds maximum size of {MAX_UPLOAD_BYTES // (1024 * 1024)} MB.",
            ).model_dump(),
        )

    result = await _service.decode_from_bytes(raw, source_label=file.filename or "upload")

    if not result.success:
        logger.warning("QR decode failed for uploaded file", extra={
            "filename": file.filename, "error": result.error_message,
        })
        raise HTTPException(
            status_code=422,
            detail=QRDecodeResponse(
                success=False, time_ms=result.processing_time_ms, decoded=[], count=0,
                error_message=result.error_message,
            ).model_dump(),
        )

    items = [DecodedQR(**item) for item in result.decoded_data]
    logger.info("QR decode successful", extra={
        "filename": file.filename, "count": len(items),
    })
    return QRDecodeResponse(
        success=True, time_ms=result.processing_time_ms,
        decoded=items, count=len(items), error_message=None,
    )


@router.post(
    "/qr-decode/url",
    response_model=QRDecodeResponse,
    summary="Decode QR code from an image URL",
    description="Provide a public URL to an image containing a QR code and get its decoded content.",
)
async def decode_qr_url(
    body: QRDecodeUrlRequest,
) -> QRDecodeResponse:
    start = time.perf_counter()

    if not body.url.lower().startswith(("http://", "https://")):
        elapsed = round((time.perf_counter() - start) * 1000, 3)
        raise HTTPException(
            status_code=400,
            detail=QRDecodeResponse(
                success=False, time_ms=elapsed, decoded=[], count=0,
                error_message="URL must start with http:// or https://.",
            ).model_dump(),
        )

    result = await _service.decode_from_url(body.url)

    if not result.success:
        logger.warning("QR decode failed for URL", extra={
            "url": body.url, "error": result.error_message,
        })
        raise HTTPException(
            status_code=422,
            detail=QRDecodeResponse(
                success=False, time_ms=result.processing_time_ms, decoded=[], count=0,
                error_message=result.error_message,
            ).model_dump(),
        )

    items = [DecodedQR(**item) for item in result.decoded_data]
    logger.info("QR decode successful", extra={
        "url": body.url, "count": len(items),
    })
    return QRDecodeResponse(
        success=True, time_ms=result.processing_time_ms,
        decoded=items, count=len(items), error_message=None,
    )