# app.py
import os, json, joblib
from typing import List, Dict, Any, Optional
import pandas as pd
from fastapi import FastAPI, HTTPException, Body, Query
from fastapi.responses import RedirectResponse
from pydantic import BaseModel, Field

# ====== Artefatos ======
ARTIFACT_DIR = os.getenv("ARTIFACT_DIR", "model")  # <-- padrão agora é 'model'
PREPROCESS_PATH = os.path.join(ARTIFACT_DIR, "preprocess.joblib")
MODEL_PATH      = os.path.join(ARTIFACT_DIR, "xgb_model.joblib")
META_PATH       = os.path.join(ARTIFACT_DIR, "metadata.json")

try:
    preprocess = joblib.load(PREPROCESS_PATH)
    model = joblib.load(MODEL_PATH)
    with open(META_PATH, "r", encoding="utf-8") as f:
        META: Dict[str, Any] = json.load(f)
except Exception as e:
    raise RuntimeError(f"Falha ao carregar artefatos: {e}")

BEST_T = float(META.get("best_threshold", 0.5))
VERSION = str(META.get("version", "1.0"))
CAT_COLS: List[str] = list(META.get("cat_cols", []))
NUM_COLS: List[str] = list(META.get("num_cols", []))
RAW_FEATURES: List[str] = CAT_COLS + NUM_COLS  # ordem esperada pelo preprocess

# exemplo (mesmo do seu teste)
EXAMPLE_PAYLOAD = {
    "checking_status": "A12",
    "credit_duration_months": 24,
    "credit_history": "A32",
    "loan_purpose": "A43",
    "credit_amount": 3500,
    "savings_account": "A61",
    "employment_duration": "A73",
    "installment_rate": 3,
    "personal_status_sex": "A93",
    "guarantors": "A101",
    "residence_since": 2,
    "property_type": "A121",
    "age_years": 35,
    "other_installment_plans": "A143",
    "housing_type": "A152",
    "existing_credits": 1,
    "job_type": "A173",
    "dependents": 1,
    "telephone": "A192",
    "foreign_worker": "A202"
}

# =============================================================================
# FastAPI metadata (Swagger super detalhado)
# =============================================================================
DESCRIPTION = """
**IVerify — API de Decisão de Crédito (fraude/inadimplência)**

- **Modelo**: XGBoost (classificador binário)
- **Pré-processamento**: pipeline (OneHotEncoder com `handle_unknown="ignore"`, scaler/num, etc.)
- **Saída**:
  - `prob_approved` (probabilidade de aprovação)
  - `approved` (0/1) de acordo com `threshold` (padrão: `best_threshold` dos metadados)
- **Threshold**:
  - Otimizado via política de custo definida no treino (`metadata.json` → `cost_matrix`).
  - Pode ser sobrescrito por query `?threshold=0.42` nos endpoints de predição.

**Endpoints principais**
- `GET /health` — status e metadados do modelo
- `GET /schema` — colunas esperadas (raw), rótulos e exemplo
- `GET /sample` — payload pronto para teste
- `POST /predict` — predição única (prob + decisão)
- `POST /predict_batch` — predição em lote

**Observabilidade**
- Respostas incluem `meta_version`, e (quando aplicável) campos extras ignorados.

> **Atenção**: garanta que o payload contenha **todas** as colunas `RAW_FEATURES` esperadas pelo preprocess.
"""

TAGS = [
    {"name": "Health", "description": "Status, versão e metadados do modelo."},
    {"name": "Schema", "description": "Colunas esperadas, exemplo de payload e labels."},
    {"name": "Inference", "description": "Predição única e em lote com threshold configurável."},
]

app = FastAPI(
    title="IVerify — Credit Decision API",
    version=VERSION,
    description=DESCRIPTION,
    contact={
        "name": "IVerify",
        "url": "https://github.com/ViniciusKanh",
    },
    license_info={"name": "MIT"},
    openapi_tags=TAGS,
)

# =============================================================================
# Schemas (Pydantic)
# =============================================================================
class Application(BaseModel):
    # Campos **RAW** (antes do OneHot). Nomes devem bater com o treino.
    checking_status: str = Field(..., examples=["A12"])
    credit_duration_months: int = Field(..., ge=1, examples=[24])
    credit_history: str = Field(..., examples=["A32"])
    loan_purpose: str = Field(..., examples=["A43"])
    credit_amount: float = Field(..., gt=0, examples=[3500])
    savings_account: str = Field(..., examples=["A61"])
    employment_duration: str = Field(..., examples=["A73"])
    installment_rate: int = Field(..., ge=1, le=4, examples=[3])
    personal_status_sex: str = Field(..., examples=["A93"])
    guarantors: str = Field(..., examples=["A101"])
    residence_since: int = Field(..., ge=1, examples=[2])
    property_type: str = Field(..., examples=["A121"])
    age_years: int = Field(..., ge=18, examples=[35])
    other_installment_plans: str = Field(..., examples=["A143"])
    housing_type: str = Field(..., examples=["A152"])
    existing_credits: int = Field(..., ge=0, examples=[1])
    job_type: str = Field(..., examples=["A173"])
    dependents: int = Field(..., ge=0, examples=[1])
    telephone: str = Field(..., examples=["A192"])
    foreign_worker: str = Field(..., examples=["A202"])

class PredictResponse(BaseModel):
    prob_approved: float
    approved: int
    threshold: float
    meta_version: Optional[str] = None
    extra_fields_ignored: Optional[List[str]] = None

class BatchRequest(BaseModel):
    items: List[Application]
    threshold: Optional[float] = Field(None, description="Sobrescreve o threshold global (opcional).")

class BatchResponseItem(PredictResponse):
    pass

class BatchResponse(BaseModel):
    results: List[BatchResponseItem]

# =============================================================================
# Helpers
# =============================================================================
def _to_frame(payload: Dict[str, Any]) -> pd.DataFrame:
    df = pd.DataFrame([payload])
    missing = [c for c in RAW_FEATURES if c not in df.columns]
    if missing:
        raise HTTPException(status_code=400, detail={
            "error": "missing_required_features",
            "missing": missing
        })
    # Reordena e descarta extras
    extras = [c for c in df.columns if c not in RAW_FEATURES]
    df = df[RAW_FEATURES]
    if extras:
        df.attrs["extra_cols"] = extras
    return df

def _predict_one(d: Dict[str, Any], thr: float) -> Dict[str, Any]:
    X = _to_frame(d)
    try:
        Xp = preprocess.transform(X)
        proba = float(model.predict_proba(Xp)[:, 1][0])  # prob da classe positiva (aprovado)
    except Exception as e:
        raise HTTPException(status_code=500, detail={"error": "inference_failed", "msg": str(e)})

    resp = {
        "prob_approved": proba,
        "approved": int(proba >= thr),
        "threshold": float(thr),
        "meta_version": VERSION,
    }
    extras = X.attrs.get("extra_cols")
    if extras:
        resp["extra_fields_ignored"] = extras
    return resp

# =============================================================================
# Rotas
# =============================================================================
@app.get("/", include_in_schema=False)
def root():
    return RedirectResponse(url="/docs")

@app.get("/health", tags=["Health"])
def health():
    return {
        "status": "ok",
        "model_loaded": True,
        "version": VERSION,
        "threshold": BEST_T,
        "features_raw_expected": RAW_FEATURES,
        "cost_matrix": META.get("cost_matrix"),
    }

@app.get("/schema", tags=["Schema"])
def schema():
    return {
        "features_raw": RAW_FEATURES,
        "labels": {0: "Negado", 1: "Aprovado"},
        "positive_class": 1,
        "example_payload": EXAMPLE_PAYLOAD,
    }

@app.get("/sample", tags=["Schema"])
def sample():
    return {"payload": EXAMPLE_PAYLOAD}

@app.post(
    "/predict",
    tags=["Inference"],
    response_model=PredictResponse,
    summary="Predição única (probabilidade e decisão)",
)
def predict(
    payload: Application = Body(
        ...,
        example=EXAMPLE_PAYLOAD,
        description="Payload cru (antes do OneHot), com as mesmas colunas usadas no treino.",
    ),
    threshold: Optional[float] = Query(
        None, description="Opcional. Sobrescreve o threshold global."
    ),
):
    thr = float(threshold) if threshold is not None else BEST_T
    return _predict_one(payload.model_dump(), thr)

@app.post(
    "/predict_batch",
    tags=["Inference"],
    response_model=BatchResponse,
    summary="Predição em lote",
)
def predict_batch(request: BatchRequest):
    thr = float(request.threshold) if request.threshold is not None else BEST_T
    results = [_predict_one(item.model_dump(), thr) for item in request.items]
    return {"results": results}