"""OCR 마이크로서비스 — Surya OCR 0.17.x (GPU) + PyMuPDF (PDF→이미지)

페이지 단위 스트리밍으로 대형 PDF도 메모리 피크 억제.
모델은 첫 요청 시 lazy loading.
"""

import asyncio
import time
import unicodedata
from pathlib import Path

import fitz
import torch
from fastapi import FastAPI
from fastapi.responses import JSONResponse
from PIL import Image, ImageDraw

app = FastAPI()

_models = None

IMAGE_EXTS = {".jpg", ".jpeg", ".png", ".tiff", ".tif", ".bmp", ".gif", ".webp"}


def _resolve_path(file_path: str) -> Path | None:
    """NFC(DB) vs NFD(NFS) 한글 경로 정규화 차이 흡수."""
    candidates = [file_path,
                  unicodedata.normalize("NFD", file_path),
                  unicodedata.normalize("NFC", file_path)]
    for c in candidates:
        p = Path(c)
        if p.exists():
            return p
    # 마지막 fallback: parent 디렉토리에서 이름을 NFC 로 매칭
    parent = Path(file_path).parent
    if parent.exists():
        target = unicodedata.normalize("NFC", Path(file_path).name)
        for child in parent.iterdir():
            if unicodedata.normalize("NFC", child.name) == target:
                return child
    return None


def _load_models():
    """Surya 0.17 predictors lazy loading — 첫 호출 시만"""
    global _models
    if _models is not None:
        return _models

    from surya.detection import DetectionPredictor
    from surya.recognition import FoundationPredictor, RecognitionPredictor

    foundation = FoundationPredictor()
    _models = {
        "detection": DetectionPredictor(),
        "recognition": RecognitionPredictor(foundation),
    }
    return _models


def _ocr_image(image: Image.Image) -> str:
    m = _load_models()
    results = m["recognition"]([image], det_predictor=m["detection"])
    if not results:
        return ""
    return "\n".join(line.text for line in results[0].text_lines)


@app.get("/health")
def health():
    """Liveness — Docker healthcheck용, 프로세스 생존 확인"""
    return {"status": "ok", "service": "ocr-surya"}


@app.get("/ready")
def ready():
    """Readiness — 배포 검증용, CUDA + 모델 상태"""
    cuda_ok = torch.cuda.is_available()
    models_loaded = _models is not None
    return {
        "ready": cuda_ok and models_loaded,
        "cuda": cuda_ok,
        "models_loaded": models_loaded,
        "gpu_name": torch.cuda.get_device_name(0) if cuda_ok else None,
    }


@app.get("/smoke")
async def smoke():
    """OCR 라운드트립이 예외 없이 완료되는지 운영 verify. Docker healthcheck 미사용."""
    start = time.monotonic()
    img = Image.new("RGB", (160, 60), color="white")
    draw = ImageDraw.Draw(img)
    draw.text((30, 20), "OK", fill="black")
    try:
        loop = asyncio.get_running_loop()
        await asyncio.wait_for(
            loop.run_in_executor(None, _ocr_image, img),
            timeout=20.0,
        )
    except asyncio.TimeoutError:
        return JSONResponse(status_code=503, content={"status": "degraded", "reason": "timeout"})
    except Exception as exc:
        return JSONResponse(
            status_code=503,
            content={"status": "degraded", "reason": exc.__class__.__name__},
        )
    elapsed_ms = int((time.monotonic() - start) * 1000)
    return {"status": "ok", "service": "ocr-service", "inference": "ok", "elapsed_ms": elapsed_ms}


@app.post("/ocr")
async def ocr_endpoint(body: dict):
    """PDF/이미지 OCR — 페이지 단위 처리 (전체 일괄 로드 금지)"""
    raw_path = body["filePath"]
    max_pages = body.get("maxPages", 200)

    resolved = _resolve_path(raw_path)
    if resolved is None:
        return {"error": f"파일 없음: {raw_path}", "text": "", "pages": 0, "chars": 0}

    ext = resolved.suffix.lower()

    if ext in IMAGE_EXTS:
        img = Image.open(resolved).convert("RGB")
        try:
            text = _ocr_image(img)
        finally:
            del img
        return {"text": text, "pages": 1, "chars": len(text)}

    doc = fitz.open(str(resolved))
    try:
        page_count = len(doc)
        process_pages = min(page_count, max_pages)
        all_text = []
        for i in range(process_pages):
            pix = doc[i].get_pixmap(dpi=200)
            img = Image.frombytes("RGB", [pix.width, pix.height], pix.samples)
            del pix
            try:
                page_text = _ocr_image(img)
            finally:
                del img
            if page_text.strip():
                all_text.append(page_text)
    finally:
        doc.close()

    combined = "\n\n".join(all_text)
    return {"text": combined, "pages": page_count, "chars": len(combined)}