from __future__ import annotations

from pathlib import Path

import fitz

from backend.app.services.markdown_builder import title_from_path
from backend.app.services.processors.base import ProcessedContent
from backend.app.services.providers.mistral_client import MistralClient


class PdfProcessor:
    def __init__(self, use_ocr: bool = False, page_ranges: str | None = None):
        self.use_ocr = use_ocr
        self.page_ranges = page_ranges

    def process(self, path: Path) -> ProcessedContent:
        if self.use_ocr:
            return self._process_ocr(path)
        doc = fitz.open(path)
        pages: list[str] = []
        for index in self._selected_pages(len(doc)):
            page = doc[index - 1]
            text = page.get_text("text").strip()
            if text:
                pages.append(f"## Pagina {index}\n\n{text}")
        body = "\n\n".join(pages).strip()
        if len(body) < 80:
            raise RuntimeError("El PDF tiene poco texto extraible; procesalo con OCR")
        return ProcessedContent(title=title_from_path(path), body=body, processor="pdf-text")

    def _process_ocr(self, path: Path) -> ProcessedContent:
        doc = fitz.open(path)
        client = MistralClient()
        parts: list[str] = []
        temp_paths: list[Path] = []
        try:
            for index in self._selected_pages(len(doc)):
                page = doc[index - 1]
                pix = page.get_pixmap(matrix=fitz.Matrix(2, 2), alpha=False)
                image_path = path.with_name(f"{path.stem}-page-{index}.jpg")
                pix.save(image_path)
                temp_paths.append(image_path)
                parts.append(f"## Pagina {index}\n\n{client.ocr_image(image_path)}")
        finally:
            for temp_path in temp_paths:
                temp_path.unlink(missing_ok=True)
        return ProcessedContent(title=title_from_path(path), body="\n\n".join(parts), processor="mistral-ocr")

    def _selected_pages(self, total_pages: int) -> list[int]:
        if total_pages < 1:
            raise RuntimeError("El PDF no tiene paginas")
        if not self.page_ranges or not self.page_ranges.strip():
            return list(range(1, total_pages + 1))

        selected: list[int] = []
        for raw_part in self.page_ranges.split(","):
            part = raw_part.strip()
            if not part:
                continue
            if "-" in part:
                start_text, end_text = [piece.strip() for piece in part.split("-", 1)]
                if not start_text.isdigit() or not end_text.isdigit():
                    raise RuntimeError(f"Rango de paginas invalido: {part}")
                start = int(start_text)
                end = int(end_text)
                if start > end:
                    raise RuntimeError(f"Rango de paginas invertido: {part}")
                selected.extend(range(start, end + 1))
            else:
                if not part.isdigit():
                    raise RuntimeError(f"Pagina invalida: {part}")
                selected.append(int(part))

        unique_pages = sorted(set(selected))
        invalid = [page for page in unique_pages if page < 1 or page > total_pages]
        if invalid:
            raise RuntimeError(f"Paginas fuera de rango: {', '.join(map(str, invalid))}. El PDF tiene {total_pages} paginas")
        if not unique_pages:
            raise RuntimeError("No se seleccionaron paginas para procesar")
        return unique_pages