"""Moteur Step & Repeat : dupliquer une page plusieurs fois sur une feuille."""

from pypdf import PdfReader, PdfWriter, PageObject, Transformation
from .pdf_utils import get_page_size, smart_crop_marks
import math


def step_and_repeat(input_path, output_path, sheet_size=(841.89, 595.28),
                    copies_h=None, copies_v=None, spacing_h=0, spacing_v=0,
                    crop_marks=False):
    """Dupliquer chaque page sur une feuille.

    copies_h, copies_v: nombre de copies horizontales/verticales (None = auto)
    spacing_h, spacing_v: espacement en points
    """
    reader = PdfReader(input_path)
    sheet_w, sheet_h = sheet_size
    writer = PdfWriter()

    for page in reader.pages:
        page_w, page_h = get_page_size(page)

        # Auto-calcul du nombre de copies
        if copies_h is None:
            copies_h_calc = max(1, int((sheet_w + spacing_h) / (page_w + spacing_h)))
        else:
            copies_h_calc = copies_h

        if copies_v is None:
            copies_v_calc = max(1, int((sheet_h + spacing_v) / (page_h + spacing_v)))
        else:
            copies_v_calc = copies_v

        # Centrage sur la feuille
        total_w = copies_h_calc * page_w + (copies_h_calc - 1) * spacing_h
        total_h = copies_v_calc * page_h + (copies_v_calc - 1) * spacing_v
        start_x = (sheet_w - total_w) / 2
        start_y = (sheet_h - total_h) / 2

        sheet = PageObject.create_blank_page(width=sheet_w, height=sheet_h)
        grid_positions = []

        for row in range(copies_v_calc):
            for col in range(copies_h_calc):
                x = start_x + col * (page_w + spacing_h)
                y = start_y + (copies_v_calc - 1 - row) * (page_h + spacing_v)

                overlay = PageObject.create_blank_page(width=sheet_w, height=sheet_h)
                overlay.merge_page(page)
                overlay.add_transformation(Transformation().translate(x, y))
                sheet.merge_page(overlay)
                grid_positions.append((col, row))

        if crop_marks and grid_positions:
            marks = smart_crop_marks(
                sheet_w, sheet_h, grid_positions,
                page_w + spacing_h, page_h + spacing_v,
                start_x, sheet_h - start_y - total_h
            )
            sheet.merge_page(marks)

        writer.add_page(sheet)

    with open(output_path, "wb") as f:
        writer.write(f)
    return output_path