# main.py
import os
import logging
from fastapi import FastAPI, UploadFile, File, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import FileResponse, JSONResponse
from fastapi.staticfiles import StaticFiles
from starlette.status import HTTP_400_BAD_REQUEST, HTTP_500_INTERNAL_SERVER_ERROR

from summarizer import generate_summary
from pdf_reader import extract_text_from_pdf

# Логтау
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger("summarizer_app")

app = FastAPI(title="Scientific Article Summarizer")

# CORS (frontend ↔ backend)
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_methods=["*"],
    allow_headers=["*"],
)

# Статикалық файлдар — жобаның түбірінен береді
app.mount("/static", StaticFiles(directory="."), name="static")

@app.get("/")
async def root():
    return FileResponse("index.html")

@app.post("/summarize/text")
async def summarize_text(data: dict):
    text = data.get("text", "")
    if not text or not text.strip():
        raise HTTPException(status_code=HTTP_400_BAD_REQUEST, detail="No text provided.")
    try:
        summary = generate_summary(text)
        return {"summary": summary}
    except Exception as e:
        logger.exception("Error while generating text summary")
        raise HTTPException(status_code=HTTP_500_INTERNAL_SERVER_ERROR, detail=str(e))

MAX_PDF_BYTES = int(os.getenv("MAX_PDF_BYTES", 10 * 1024 * 1024))  # 10 MB default

@app.post("/summarize/pdf")
async def summarize_pdf(file: UploadFile = File(...)):
    if not file.filename.lower().endswith(".pdf"):
        raise HTTPException(status_code=HTTP_400_BAD_REQUEST, detail="Only PDF files are supported.")
    pdf_bytes = await file.read()
    if len(pdf_bytes) == 0:
        raise HTTPException(status_code=HTTP_400_BAD_REQUEST, detail="Uploaded PDF is empty.")
    if len(pdf_bytes) > MAX_PDF_BYTES:
        raise HTTPException(status_code=HTTP_400_BAD_REQUEST, detail=f"PDF too large (max {MAX_PDF_BYTES} bytes).")
    try:
        text = extract_text_from_pdf(pdf_bytes)
        if not text or not text.strip():
            return {"summary": "PDF is empty or could not be processed."}
        summary = generate_summary(text)
        return {"summary": summary}
    except Exception as e:
        logger.exception("Error while processing PDF")
        raise HTTPException(status_code=HTTP_500_INTERNAL_SERVER_ERROR, detail=str(e))

# Custom error handler example
@app.exception_handler(HTTPException)
async def http_exception_handler(request, exc: HTTPException):
    return JSONResponse(status_code=exc.status_code, content={"error": exc.detail})