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Stefanescu Mihai
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"""KDP-specific formatting: margins, front matter, page numbering, TOC.
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Assembles a complete print-ready PDF book that meets Amazon KDP
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requirements for trim size, margins (including gutter), page count,
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and includes professional front matter.
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"""
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import datetime
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import logging
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from typing import Optional
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from reportlab.lib.styles import ParagraphStyle
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from reportlab.lib.units import inch
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from reportlab.pdfgen.canvas import Canvas
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from reportlab.platypus import Frame, Paragraph
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from models import Crossword, PuzzleBook, TrimSize
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from renderer import render_puzzle_page, render_solution_page
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logger = logging.getLogger(__name__)
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# ---------------------------------------------------------------------------
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# KDP constraints
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# ---------------------------------------------------------------------------
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KDP_MIN_PAGES = 24
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KDP_MAX_PAGES = 828
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_OUTSIDE_MARGIN = 0.5 # inches — top, bottom, outside edge
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_TOP_MARGIN = 0.5
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_BOTTOM_MARGIN = 0.6 # slightly more room for the page number
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_PAGE_NUM_FONT = "Helvetica"
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_PAGE_NUM_SIZE = 9
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# ---------------------------------------------------------------------------
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# Margin helpers
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# ---------------------------------------------------------------------------
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def _gutter_margin(page_count: int) -> float:
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"""KDP minimum inside (gutter) margin in inches, based on page count."""
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if page_count <= 150:
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return 0.375
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if page_count <= 300:
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return 0.5
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if page_count <= 500:
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return 0.625
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if page_count <= 700:
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return 0.75
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return 0.875
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def _content_rect(trim: TrimSize, abs_page: int,
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gutter: float) -> tuple[float, float, float, float]:
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"""Return (content_x, content_top_y, content_w, content_h) in points.
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Odd pages (recto) have the gutter on the *left*;
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even pages (verso) have the gutter on the *right*.
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"""
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pw = trim.width * inch
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ph = trim.height * inch
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outside = _OUTSIDE_MARGIN * inch
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gut = gutter * inch
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top = _TOP_MARGIN * inch
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bot = _BOTTOM_MARGIN * inch
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if abs_page % 2 == 1: # recto — gutter left
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content_x = gut
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else: # verso — gutter right
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content_x = outside
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content_w = pw - gut - outside
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content_top_y = ph - top
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content_h = ph - top - bot
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return content_x, content_top_y, content_w, content_h
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# ---------------------------------------------------------------------------
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# Page-count estimation
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# ---------------------------------------------------------------------------
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def _estimate_page_count(puzzle_count: int,
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solutions_at_end: bool,
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include_toc: bool,
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include_instructions: bool) -> int:
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"""Pre-calculate total pages so the gutter margin can be determined."""
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front = 2 # title + copyright
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if include_toc:
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front += 1
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if include_instructions:
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front += 1
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if front % 2 != 0: # pad so puzzles start recto
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front += 1
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content = puzzle_count * 2 # puzzle page + solution page
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return front + content
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# ---------------------------------------------------------------------------
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# Front-matter pages
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# ---------------------------------------------------------------------------
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def _draw_title_page(cv: Canvas, title: str, author: str,
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pw: float, ph: float) -> None:
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y_title = ph * 0.58
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cv.setFont("Helvetica-Bold", 30)
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cv.setFillColorRGB(0, 0, 0)
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tw = cv.stringWidth(title, "Helvetica-Bold", 30)
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cv.drawString((pw - tw) / 2, y_title, title)
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# Decorative rule
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rule_w = min(pw * 0.35, 180)
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cv.setStrokeColorRGB(0.35, 0.35, 0.35)
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cv.setLineWidth(0.75)
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rule_y = y_title - 18
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cv.line((pw - rule_w) / 2, rule_y, (pw + rule_w) / 2, rule_y)
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if author:
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cv.setFont("Helvetica", 16)
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cv.setFillColorRGB(0.25, 0.25, 0.25)
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aw = cv.stringWidth(author, "Helvetica", 16)
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cv.drawString((pw - aw) / 2, rule_y - 28, author)
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def _draw_copyright_page(cv: Canvas, title: str, author: str,
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pw: float, ph: float) -> None:
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year = datetime.date.today().year
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style = ParagraphStyle(
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"Copyright", fontName="Helvetica", fontSize=9, leading=13,
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spaceBefore=3, spaceAfter=3,
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)
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items: list[Paragraph] = [
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Paragraph(f"<i>{title}</i>", style),
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]
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if author:
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items.append(Paragraph(f"Copyright © {year} {author}", style))
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items.extend([
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Paragraph("All rights reserved.", style),
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Paragraph(
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"No part of this publication may be reproduced, distributed, "
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"or transmitted in any form without prior written permission.",
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style),
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Paragraph(f"First published {year}.", style),
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])
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margin = 0.75 * inch
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Frame(margin, margin, pw - 2 * margin, ph * 0.25,
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leftPadding=0, rightPadding=0,
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topPadding=0, bottomPadding=0).addFromList(items, cv)
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def _draw_instructions_page(cv: Canvas, pw: float, ph: float,
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solutions_at_end: bool) -> None:
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margin = 0.75 * inch
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content_w = pw - 2 * margin
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cv.setFont("Helvetica-Bold", 20)
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cv.setFillColorRGB(0, 0, 0)
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heading = "How to Solve"
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hw = cv.stringWidth(heading, "Helvetica-Bold", 20)
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heading_y = ph - margin - 20
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cv.drawString((pw - hw) / 2, heading_y, heading)
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style = ParagraphStyle(
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"Instructions", fontName="Helvetica", fontSize=11, leading=16,
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spaceBefore=6, spaceAfter=6,
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)
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if solutions_at_end:
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sol_note = ("Solutions for every puzzle can be found at the back "
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"of this book.")
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else:
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sol_note = ("The solution for each puzzle appears on the page "
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"immediately following it.")
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paras = [
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Paragraph(
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"Each puzzle consists of a grid of white and black squares "
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"and a set of numbered clues. Solve the clues and write one "
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"letter per white square.", style),
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Paragraph(
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"<b>Across</b> clues are answered by writing letters "
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"from left to right.", style),
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Paragraph(
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"<b>Down</b> clues are answered by writing letters "
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"from top to bottom.", style),
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Paragraph(
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"Where an across answer and a down answer share a square, "
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"the letter must be the same for both words — these "
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"intersections are your best starting points!", style),
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Paragraph(f"{sol_note} Good luck and have fun!", style),
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]
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frame_top = heading_y - 16
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Frame(margin, margin, content_w, frame_top - margin,
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leftPadding=0, rightPadding=0,
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topPadding=0, bottomPadding=0).addFromList(paras, cv)
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# ---------------------------------------------------------------------------
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# Table of contents
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# ---------------------------------------------------------------------------
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def _draw_toc_page(cv: Canvas, entries: list[tuple[str, int]],
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pw: float, ph: float) -> None:
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margin = 0.75 * inch
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content_w = pw - 2 * margin
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cv.setFont("Helvetica-Bold", 20)
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cv.setFillColorRGB(0, 0, 0)
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heading = "Contents"
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hw = cv.stringWidth(heading, "Helvetica-Bold", 20)
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cv.drawString((pw - hw) / 2, ph - margin - 20, heading)
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y = ph - margin - 54
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entry_font = "Helvetica"
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entry_size = 11
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dot_spacing = 4.5
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for label, page_num in entries:
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if y < margin + 20:
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break
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cv.setFont(entry_font, entry_size)
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cv.setFillColorRGB(0, 0, 0)
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cv.drawString(margin, y, label)
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pn_text = str(page_num)
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pn_w = cv.stringWidth(pn_text, entry_font, entry_size)
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cv.drawRightString(pw - margin, y, pn_text)
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# Dotted leader
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label_end = margin + cv.stringWidth(label, entry_font, entry_size) + 8
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dots_end = pw - margin - pn_w - 8
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cv.setFillColorRGB(0.5, 0.5, 0.5)
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x = label_end
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while x < dots_end:
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cv.drawString(x, y, ".")
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x += dot_spacing
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y -= 22
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cv.setFillColorRGB(0, 0, 0)
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# ---------------------------------------------------------------------------
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# Page number
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# ---------------------------------------------------------------------------
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def _draw_page_number(cv: Canvas, display_num: int,
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pw: float, ph: float) -> None:
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cv.setFont(_PAGE_NUM_FONT, _PAGE_NUM_SIZE)
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cv.setFillColorRGB(0.4, 0.4, 0.4)
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text = str(display_num)
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tw = cv.stringWidth(text, _PAGE_NUM_FONT, _PAGE_NUM_SIZE)
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cv.drawString((pw - tw) / 2, 0.32 * inch, text)
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# ---------------------------------------------------------------------------
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# Public API
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# ---------------------------------------------------------------------------
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def render_kdp_book(
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book: PuzzleBook,
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output_path: str,
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include_toc: bool = True,
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include_instructions: bool = True,
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) -> int:
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"""Render a complete KDP-ready PDF book.
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Returns the total page count.
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Raises ValueError if the resulting page count falls outside KDP's
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allowed range (24–828).
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"""
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trim = book.trim_size
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pw = trim.width * inch
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ph = trim.height * inch
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n = len(book.puzzles)
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if n == 0:
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raise ValueError("No puzzles to render.")
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# --- page layout --------------------------------------------------------
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total_pages = _estimate_page_count(
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n, book.solutions_at_end, include_toc, include_instructions)
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if total_pages < KDP_MIN_PAGES:
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logger.warning(
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"Book has %d pages, below KDP minimum of %d. "
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"Consider adding more puzzles.", total_pages, KDP_MIN_PAGES)
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if total_pages > KDP_MAX_PAGES:
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raise ValueError(
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f"Book has {total_pages} pages, exceeding KDP maximum of "
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f"{KDP_MAX_PAGES}.")
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gutter = _gutter_margin(total_pages)
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logger.info("Book layout: %d pages, trim %s, gutter %.3f\".",
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total_pages, trim, gutter)
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# --- TOC entries (display page numbers) ---------------------------------
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toc_entries: list[tuple[str, int]] = []
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if include_toc:
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if book.solutions_at_end:
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for i in range(n):
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toc_entries.append((f"Puzzle {i + 1}", i + 1))
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toc_entries.append(("Solutions", n + 1))
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else:
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for i in range(n):
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toc_entries.append((f"Puzzle {i + 1}", i * 2 + 1))
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# --- render -------------------------------------------------------------
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cv = Canvas(output_path, pagesize=(pw, ph))
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abs_page = 0
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# -- front matter (no page numbers) --
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abs_page += 1
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_draw_title_page(cv, book.title, book.author, pw, ph)
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cv.showPage()
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abs_page += 1
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_draw_copyright_page(cv, book.title, book.author, pw, ph)
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cv.showPage()
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if include_toc:
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abs_page += 1
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_draw_toc_page(cv, toc_entries, pw, ph)
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cv.showPage()
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if include_instructions:
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abs_page += 1
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_draw_instructions_page(cv, pw, ph, book.solutions_at_end)
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cv.showPage()
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# Pad so puzzles start on a recto (odd absolute page)
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while abs_page % 2 != 0:
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abs_page += 1
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cv.showPage()
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# -- content pages -------------------------------------------------------
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display = 0
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if book.solutions_at_end:
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for i, puzzle in enumerate(book.puzzles, 1):
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abs_page += 1
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display += 1
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cx, cy, cw, ch = _content_rect(trim, abs_page, gutter)
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render_puzzle_page(cv, puzzle, i, cx, cy, cw, ch)
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_draw_page_number(cv, display, pw, ph)
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cv.showPage()
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for i, puzzle in enumerate(book.puzzles, 1):
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abs_page += 1
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display += 1
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cx, cy, cw, ch = _content_rect(trim, abs_page, gutter)
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render_solution_page(cv, puzzle, i, cx, cy, cw, ch)
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_draw_page_number(cv, display, pw, ph)
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cv.showPage()
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else:
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for i, puzzle in enumerate(book.puzzles, 1):
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abs_page += 1
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display += 1
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cx, cy, cw, ch = _content_rect(trim, abs_page, gutter)
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render_puzzle_page(cv, puzzle, i, cx, cy, cw, ch)
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_draw_page_number(cv, display, pw, ph)
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cv.showPage()
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abs_page += 1
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display += 1
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cx, cy, cw, ch = _content_rect(trim, abs_page, gutter)
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render_solution_page(cv, puzzle, i, cx, cy, cw, ch)
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_draw_page_number(cv, display, pw, ph)
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cv.showPage()
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cv.save()
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logger.info("Wrote %d-page KDP book to %s.", abs_page, output_path)
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return abs_page
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