#!/usr/bin/env python3
"""Render each docs/modules/*.md file to a PDF via reportlab."""

from __future__ import annotations

from pathlib import Path

from reportlab.lib.pagesizes import letter
from reportlab.lib.styles import ParagraphStyle, getSampleStyleSheet
from reportlab.lib.units import inch
from reportlab.platypus import PageBreak, Paragraph, Preformatted, SimpleDocTemplate, Spacer

ROOT = Path(__file__).resolve().parents[1]
MD_ROOT = ROOT / "docs" / "modules"
PDF_ROOT = ROOT / "docs" / "modules-pdf"


def md_to_flowables(text: str, styles):
    story = []
    in_code = False
    code_buf = []
    for raw in text.splitlines():
        line = raw.rstrip()
        if line.startswith("```"):
            if in_code:
                story.append(Preformatted("\n".join(code_buf) or " ", styles["ModuleCode"]))
                code_buf = []
                in_code = False
            else:
                in_code = True
            continue
        if in_code:
            code_buf.append(line)
            continue
        if line.startswith("# "):
            story.append(Paragraph(esc(line[2:]), styles["Title"]))
        elif line.startswith("## "):
            story.append(Spacer(1, 8))
            story.append(Paragraph(esc(line[3:]), styles["Heading2"]))
        elif line.startswith("### "):
            story.append(Paragraph(esc(line[4:]), styles["Heading3"]))
        elif line.startswith("|"):
            story.append(Paragraph(esc(line.replace("|", " · ")), styles["BodyText"]))
        elif line.startswith("- "):
            story.append(Paragraph("• " + esc(line[2:]), styles["BodyText"]))
        elif line.strip() == "":
            story.append(Spacer(1, 6))
        else:
            story.append(Paragraph(esc(line), styles["BodyText"]))
    return story


def esc(s: str) -> str:
    return (
        s.replace("&", "&")
        .replace("<", "&lt;")
        .replace(">", "&gt;")
        .replace("`", "")
    )


def main() -> None:
    PDF_ROOT.mkdir(parents=True, exist_ok=True)
    styles = getSampleStyleSheet()
    styles.add(
        ParagraphStyle(
            name="ModuleCode",
            fontName="Courier",
            fontSize=7,
            leading=9,
        )
    )
    mds = sorted(MD_ROOT.rglob("*.md"))
    n = 0
    combined = []
    for md in mds:
        rel = md.relative_to(MD_ROOT)
        pdf_path = PDF_ROOT / rel.with_suffix(".pdf")
        pdf_path.parent.mkdir(parents=True, exist_ok=True)
        text = md.read_text(encoding="utf-8", errors="replace")
        doc = SimpleDocTemplate(
            str(pdf_path),
            pagesize=letter,
            leftMargin=0.7 * inch,
            rightMargin=0.7 * inch,
            topMargin=0.7 * inch,
            bottomMargin=0.7 * inch,
        )
        flow = md_to_flowables(text, styles)
        doc.build(flow)
        combined.extend(flow)
        combined.append(PageBreak())
        n += 1

    try:
        from pypdf import PdfWriter

        writer = PdfWriter()
        for md in mds:
            pdf_path = PDF_ROOT / md.relative_to(MD_ROOT).with_suffix(".pdf")
            if pdf_path.exists():
                writer.append(str(pdf_path))
        book = PDF_ROOT / "ALL-MODULES.pdf"
        with open(book, "wb") as fh:
            writer.write(fh)
        print(f"wrote {n} pdfs + {book.name}")
    except Exception as exc:
        print(f"wrote {n} pdfs (combined book skipped: {exc})")


if __name__ == "__main__":
    main()