"""
main.py — FastAPI application entry point.
"""
import os
import mimetypes

# Fix for missing PDF MIME type on some Linux environments (Hugging Face)
mimetypes.add_type('application/pdf', '.pdf')
mimetypes.add_type('image/png', '.png')

from contextlib import asynccontextmanager
from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from fastapi.staticfiles import StaticFiles

from config  import INDEXES_DIR
from indexes import load_indexes
from routes  import router, limiter
from slowapi.errors import RateLimitExceeded
from slowapi import _rate_limit_exceeded_handler

@asynccontextmanager
async def lifespan(app: FastAPI):
    """Load all indexes and models at startup."""
    print("DEBUG: Application starting up and loading indexes...")
    load_indexes()
    yield

app = FastAPI(
    title       = "CONTROLSAI API",
    description = "Siemens S7-1200 RAG Backend — Sprint 1",
    version     = "1.0.0",
    lifespan    = lifespan,
)
app.state.limiter = limiter
app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)

# ── CORS ─────────────────────────────────────────────────────────────────────
ALLOWED_ORIGINS = [
    "http://localhost:5173",
    "http://localhost:3000",
    "https://*.vercel.app",
    "https://*.hf.space"
]

app.add_middleware(
    CORSMiddleware,
    allow_origins  = ALLOWED_ORIGINS,
    allow_origin_regex = r"^https://.*\.vercel\.app$|^https://.*\.hf\.space$",
    allow_methods  = ["*"],
    allow_headers  = ["*"],
)

# ── Static File Mounts ───────────────────────────────────────────────────────
class SafeStaticFiles(StaticFiles):
    """Subclass of StaticFiles to inject CORS headers for PDF rendering."""
    def set_headers(self, response, stat_result):
        # Allow cross-origin access
        response.headers["Access-Control-Allow-Origin"] = "*"
        response.headers["Cross-Origin-Resource-Policy"] = "cross-origin"
        # Content-Type is now handled automatically by the mimetypes.add_type fix above
        super().set_headers(response, stat_result)

# Ensure paths are absolute (fixes HF Space mounting issues)
BASE_DIR = os.path.dirname(os.path.abspath(__file__))
abs_indexes_dir = os.path.join(BASE_DIR, "indexes")

pdfs_dir = os.path.join(abs_indexes_dir, "pdfs")
if os.path.exists(pdfs_dir):
    print(f"DEBUG: Checking PDFs folder at {pdfs_dir}")
    files = os.listdir(pdfs_dir)
    print(f"DEBUG: Found {len(files)} files in pdfs directory.")
    for f in files:
        f_path = os.path.join(pdfs_dir, f)
        size_mb = os.path.getsize(f_path) / (1024 * 1024)
        print(f"DEBUG: File: {f} | Size: {size_mb:.2f} MB")
    
    app.mount("/pdfs", SafeStaticFiles(directory=pdfs_dir), name="pdfs")
else:
    print(f"DEBUG ERROR: PDFs folder NOT found at {pdfs_dir}")

images_dir = os.path.join(abs_indexes_dir, "images")
if os.path.exists(images_dir):
    app.mount("/images", SafeStaticFiles(directory=images_dir), name="images")

# ── Routes ───────────────────────────────────────────────────────────────────
app.include_router(router)