import json
import re
from pathlib import Path
from typing import Optional

import pymupdf4llm
from groq import Groq
from loguru import logger
from pydantic import BaseModel, field_validator

PROMPT_TEMPLATE = (Path(__file__).parent / "prompts" / "invoice.prompt.txt").read_text(encoding="utf-8")


class Invoice(BaseModel):
    proveedor: str = "Desconocido"
    nif_proveedor: Optional[str] = None
    cliente: Optional[str] = None
    numero_factura: Optional[str] = None
    fecha: Optional[str] = None
    fecha_vencimiento: Optional[str] = None
    concepto: str = "Sin descripción"
    categoria: str = "Otros"
    subtotal: Optional[float] = None
    iva_porcentaje: Optional[float] = None
    iva_importe: Optional[float] = None
    total: Optional[float] = None
    moneda: str = "EUR"

    @field_validator("categoria")
    @classmethod
    def validate_categoria(cls, v: str) -> str:
        valid = {"Servicios", "Suministros", "Transporte", "Software", "Material", "Alquiler", "Otros"}
        return v if v in valid else "Otros"


def extract_text_from_pdf(pdf_path: str) -> str:
    try:
        pages = pymupdf4llm.to_markdown(pdf_path, page_chunks=True, show_progress=False)
        return "\n\n".join(p["text"] for p in pages)
    except Exception as e:
        logger.error(f"Error leyendo {pdf_path}: {e}")
        return ""


def extract_invoice_data(pdf_path: str, client: Groq, model: str = "llama-3.1-8b-instant") -> Invoice:
    text = extract_text_from_pdf(pdf_path)
    if not text.strip():
        logger.warning(f"Sin texto en {pdf_path}")
        return Invoice(proveedor=Path(pdf_path).stem)

    prompt = PROMPT_TEMPLATE.format(text=text[:4000])

    try:
        response = client.chat.completions.create(
            model=model,
            messages=[{"role": "user", "content": prompt}],
            temperature=0,
            max_tokens=512,
        )
        raw = response.choices[0].message.content.strip()

        # Extract JSON block if wrapped in markdown
        match = re.search(r"\{.*\}", raw, re.DOTALL)
        if match:
            raw = match.group(0)

        data = json.loads(raw)
        return Invoice(**data)

    except (json.JSONDecodeError, Exception) as e:
        logger.error(f"Error extrayendo datos de {pdf_path}: {e}")
        return Invoice(proveedor=Path(pdf_path).stem)