from fastapi import FastAPI, HTTPException
from fastapi.responses import FileResponse
from pathlib import Path

app = FastAPI()

# Base directory where notes are stored
NOTES_DIR = Path("notes")

@app.get("/")
def read_root():
    return {"message": "Welcome to the Notes API!"}

@app.get("/subjects")
def get_subjects():
    """Get all subjects."""
    if not NOTES_DIR.exists():
        raise HTTPException(status_code=404, detail="Notes directory not found")
    subjects = [subject.name for subject in NOTES_DIR.iterdir() if subject.is_dir()]
    return {"subjects": subjects}

@app.get("/subjects/{subject}/units")
def get_units(subject: str):
    """Get all units for a specific subject."""
    subject_path = NOTES_DIR / subject
    if not subject_path.exists() or not subject_path.is_dir():
        raise HTTPException(status_code=404, detail="Subject not found")
    units = [unit.stem for unit in subject_path.glob("*.md")]
    return {"units": units}

@app.get("/subjects/{subject}/units/{unit}")
def get_unit_notes(subject: str, unit: str):
    """Get the content of a specific unit."""
    unit_path = NOTES_DIR / subject / f"{unit}.md"
    if not unit_path.exists():
        raise HTTPException(status_code=404, detail="Unit notes not found")
    return FileResponse(unit_path)

# Optional: Serve notes as plain text or rendered HTML
@app.get("/subjects/{subject}/units/{unit}/content")
def get_unit_notes_content(subject: str, unit: str):
    """Get the content of a specific unit as plain text."""
    unit_path = NOTES_DIR / subject / f"{unit}.md"
    if not unit_path.exists():
        raise HTTPException(status_code=404, detail="Unit notes not found")
    with open(unit_path, "r", encoding="utf-8") as file:
        content = file.read()
    return {"content": content}