# app.py
from fastapi import FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel
import joblib, numpy as np, os, sys, types, re
import pandas as pd
from typing import Dict, List, Any
import preprocess_utils as pu

APP_VERSION   = "1.0.0"
PIPELINE_PATH = "artifacts/model.joblib"

# ---------- MONKEY-PATCH pour pickles entraînés dans un notebook ----------
def _ensure_main_module():
    main_mod = sys.modules.get("__main__")
    if main_mod is None or not isinstance(main_mod, types.ModuleType):
        main_mod = types.ModuleType("__main__")
        sys.modules["__main__"] = main_mod
    return main_mod

def _expose_helpers_in_main():
    main_mod = _ensure_main_module()
    helpers = {
        "to_float": pu.to_float,
        "ravel_1d": pu.ravel_1d,
        "to_1d": pu.to_1d,
        "combine_text_cols": pu.combine_text_cols,
        "clean_target_series": pu.clean_target_series,
    }
    for k, v in helpers.items():
        setattr(main_mod, k, v)

def _try_load_with_monkeypatch(path, max_retries=5):
    _expose_helpers_in_main()
    last_err = None
    for _ in range(max_retries):
        try:
            return joblib.load(path)
        except AttributeError as e:
            last_err = e
            m = re.search(r"Can't get attribute '([^']+)'", str(e))
            if m:
                missing = m.group(1)
                main_mod = _ensure_main_module()
                if not hasattr(main_mod, missing):
                    # stub identité pour continuer si une petite fonction custom manque
                    setattr(main_mod, missing, lambda *a, **k: a[0] if a else None)
            else:
                break
    raise last_err if last_err else RuntimeError("Unable to load model.")
# --------------------------------------------------------------------------

# ---------- Introspection des colonnes attendues par le preprocess ----------
REQUIRED: Dict[str, List[str]] = {"num": [], "cat": [], "text": []}

def _introspect_required_columns(pipeline_obj) -> Dict[str, List[str]]:
    req = {"num": [], "cat": [], "text": []}
    try:
        prep = pipeline_obj.named_steps.get("prep")
        transformers = getattr(prep, "transformers_", None) or getattr(prep, "transformers", [])
        for name, trans, cols in transformers:
            if name == "num" and isinstance(cols, list):
                req["num"] = list(cols)
            elif name == "cat" and isinstance(cols, list):
                req["cat"] = list(cols)
            elif isinstance(cols, list):
                # tout le reste (txt_...) -> colonnes texte individuelles
                req["text"].extend(list(cols))
    except Exception:
        pass
    # unicité
    req["text"] = list(dict.fromkeys(req["text"]))
    return req

def _make_inference_df(prof: str, course: str) -> pd.DataFrame | None:
    data: Dict[str, Any] = {}
    # colonnes texte : on remplit intelligemment
    for col in REQUIRED.get("text", []):
        c = col.lower()
        if "global" in c:
            data[col] = f"{prof} | {course}"
        elif "title" in c:
            data[col] = course
        elif "desc" in c or "description" in c:
            data[col] = course
        else:
            data[col] = (f"{prof} {course}").strip()
    # colonnes num
    for col in REQUIRED.get("num", []):
        data[col] = 0
    # colonnes cat
    for col in REQUIRED.get("cat", []):
        data[col] = "missing"
    return pd.DataFrame([data]) if data else None
# --------------------------------------------------------------------------

app = FastAPI(title="Satisfaction Grades API", version=APP_VERSION)
app.add_middleware(CORSMiddleware, allow_origins=["*"], allow_credentials=True,
                   allow_methods=["*"], allow_headers=["*"])

class Payload(BaseModel):
    professor: str
    course: str

class Prediction(BaseModel):
    grade: float

@app.on_event("startup")
def load_model():
    global pipeline, REQUIRED
    if not os.path.exists(PIPELINE_PATH):
        raise RuntimeError(f"Model file not found at {PIPELINE_PATH}")
    pipeline = _try_load_with_monkeypatch(PIPELINE_PATH)
    REQUIRED = _introspect_required_columns(pipeline)
    print(f"✅ Model loaded from {PIPELINE_PATH}")
    print("Expected columns:", REQUIRED)

@app.get("/health")
def health():
    return {"status": "ok", "version": APP_VERSION}

@app.post("/api/predict", response_model=Prediction)
def predict(payload: Payload):
    prof = (payload.professor or "").strip()
    course = (payload.course or "").strip()
    if not prof and not course:
        raise HTTPException(status_code=422, detail="Provide at least 'professor' or 'course'.")

    # 1) essayer avec DataFrame conforme au preprocess
    try:
        df = _make_inference_df(prof, course)
        if df is not None:
            y_pred = pipeline.predict(df)
            val = float(np.ravel(y_pred)[0])
            return {"grade": max(1.0, min(5.0, val))}
    except Exception as e_df:
        print(f"[WARN] DF inference failed → fallback string. Reason: {e_df}")

    # 2) fallback: pipeline qui attend une simple chaîne (cas TF-IDF unique)
    try:
        text = f"{prof} | {course}"
        y_pred = pipeline.predict([text])
        val = float(np.ravel(y_pred)[0])
        return {"grade": max(1.0, min(5.0, val))}
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Inference error: {e}")