main.py

import pickle
import numpy as np
import io
import math
from fastapi import FastAPI, File, UploadFile, HTTPException
from PIL import Image

app = FastAPI(
    title="Peruvian Sign Language (LSP) Recognition API",
    description="Sube una imagen de una seña del alfabeto de la LSP para predecir la letra correspondiente usando un Mapa Autoorganizado (SOM).",
    version="1.0.0"
)

try:
    with open('lsp_som_model.pkl', 'rb') as f:
        model_data = pickle.load(f)
    som = model_data['som']
    label_map = model_data['label_map']
    CLASSES = model_data['classes'] # La lista ['A', 'B', 'C', ...]
    IMG_SIZE = model_data['img_size'] # El tamaño de la imagen
    print("✅ Modelo y activos cargados exitosamente.")
    print(f"    - Clases reconocidas: {CLASSES}")
    print(f"    - Tamaño de imagen esperado: {IMG_SIZE}x{IMG_SIZE}")
except FileNotFoundError:
    print("❌ ERROR: No se encontró el archivo del modelo 'lsp_som_model.pkl'.")
    som = None

def preprocess_image_from_bytes(image_bytes: bytes):
    try:
        img = Image.open(io.BytesIO(image_bytes)).convert('L') # 'L' para escala de grises
        img = img.resize((IMG_SIZE, IMG_SIZE))
        img_array = np.array(img)
        img_normalized = img_array / 255.0
        return img_normalized.flatten()
    except Exception as e:
        raise HTTPException(status_code=400, detail=f"Archivo de imagen inválido. Error: {e}")

@app.get("/", tags=["Status"])
def read_root():
    return {"status": "ok", "message": "API de Reconocimiento de LSP!!"}

@app.post("/predict", tags=["Prediction"])
async def predict_sign(file: UploadFile = File(..., description="Un archivo de imagen de una seña de la LSP.")):
    if not som:
        raise HTTPException(status_code=503, detail="El modelo no está cargado.")

    image_bytes = await file.read()

    feature_vector = preprocess_image_from_bytes(image_bytes)

    winner_neuron = som.winner(feature_vector)

    predicted_index = label_map.get(winner_neuron, -1)

    # Vecino mas cercano para prediccion
    is_best_guess = False
    if predicted_index == -1:
        is_best_guess = True
        min_dist = float('inf')
        for mapped_pos, mapped_label in label_map.items():
            dist = math.sqrt((winner_neuron[0] - mapped_pos[0])**2 + (winner_neuron[1] - mapped_pos[1])**2)
            if dist < min_dist:
                min_dist = dist
                predicted_index = mapped_label
    
    if predicted_index != -1:
        predicted_letter = CLASSES[predicted_index]
        prediction_type = "Nearest Neighbor" if is_best_guess else "Direct Match"
    else:
        predicted_letter = "Unknown"
        prediction_type = "Error (No Mapped Neurons Found)"

    return {
        "filename": file.filename,
        "predicted_letter": predicted_letter,
        "prediction_type": prediction_type,
        "winner_neuron_on_map": [int(coord) for coord in winner_neuron]
    }