#!/usr/bin/env python3
"""Render a canon markdown document into a styled, self-contained artifact page.

Single source of truth: the markdown. The page is generated, never hand-edited,
so the two cannot diverge.

Design devices are recognised from conventions already present in the markdown
rather than from extra markup, so the source stays a readable document:

  * a table whose first column is `**X0**`/`**X1**`... renders as a level ladder
  * a table whose first header cell is `Threat` renders as a threat matrix
  * a table with a `Kind` column renders with mechanical/adversarial chips
  * a table whose first header cell is `E \\ P` renders as the E x P matrix
  * a blockquote renders as a pull quote
  * `**Decision N.N...**` at the start of a paragraph renders as a decision
  * `## N. Title` headings build the section rail

Stdlib only, per the estate's structure-not-tooling stance: a publishing step
that needs its own toolchain is a publishing step that stops being run.

Usage:
    python3 tools/render.py <source.md> --output <page.html> \\
        [--title "Name"] [--subtitle "..."]
"""

from __future__ import annotations

import argparse
import html
import pathlib
import re
import sys

STYLE = pathlib.Path(__file__).parent / "style.css"

INLINE_CODE = re.compile(r"`([^`]+)`")
BOLD = re.compile(r"\*\*([^*]+)\*\*")
EM = re.compile(r"(?<![*\w])\*([^*]+)\*(?!\*)")
LINK = re.compile(r"\[([^\]]+)\]\(([^)]+)\)")
HEADING = re.compile(r"^(#{1,4})\s+(.*)$")
SECTION_NO = re.compile(r"^(\d+)\.\s+(.*)$")
LEVEL_CELL = re.compile(r"^\*\*([IAEPRV])(\d)\*\*$")
DECISION = re.compile(r"^\*\*(Decision [\d.]+[^*]*)\*\*(.*)$", re.S)


def inline(text: str) -> str:
    """Escape, then apply inline markdown. Order matters: code first."""
    slots: list[str] = []

    def stash(rendered: str) -> str:
        slots.append(rendered)
        return f"\x00{len(slots) - 1}\x00"

    text = INLINE_CODE.sub(lambda m: stash(f"<code>{html.escape(m.group(1))}</code>"), text)
    text = html.escape(text, quote=False)
    text = LINK.sub(
        lambda m: f'<a href="{html.escape(m.group(2), quote=True)}">{m.group(1)}</a>', text
    )
    text = BOLD.sub(r"<strong>\1</strong>", text)
    text = EM.sub(r"<em>\1</em>", text)
    for i, rendered in enumerate(slots):
        text = text.replace(f"\x00{i}\x00", rendered)
    return text


def split_frontmatter(source: str) -> tuple[dict, str]:
    if not source.startswith("---\n"):
        return {}, source
    end = source.index("\n---\n", 4)
    meta = {}
    for line in source[4:end].splitlines():
        if ":" in line and not line.startswith((" ", "-")):
            key, _, value = line.partition(":")
            meta[key.strip()] = value.strip().strip('"')
    return meta, source[end + 5 :]


def parse_table(lines: list[str], start: int) -> tuple[list[list[str]], int]:
    rows, i = [], start
    while i < len(lines) and lines[i].lstrip().startswith("|"):
        cells = [c.strip() for c in lines[i].strip().strip("|").split("|")]
        if not all(set(c) <= set("-: ") for c in cells):
            rows.append(cells)
        i += 1
    return rows, i


# --- table renderers -------------------------------------------------------


def render_ladder(rows: list[list[str]]) -> str:
    """A level table becomes a stepped scale. Colour depth encodes strength."""
    body = rows[1:]
    axis = LEVEL_CELL.match(body[0][0]).group(1)
    names = {
        "I": "Identity", "A": "Authorization", "E": "Enforcement",
        "P": "Placement", "R": "Retention", "V": "Availability",
    }
    rungs = []
    for cells in body:
        match = LEVEL_CELL.match(cells[0])
        if not match:
            continue
        n = int(match.group(2))
        text = cells[1] if len(cells) > 1 else ""
        rungs.append(
            f'<div class="rung r{n}"><span class="code">{axis}{n}</span>'
            f'<span class="txt">{inline(text)}</span></div>'
        )
    while len(rungs) < 5:
        rungs.append('<div class="rung na"><span class="code">—</span>'
                     f'<span class="txt">Ladder ends at {axis}{len(rungs) - 1}.</span></div>')
    return (
        '<div class="ladder"><div class="pname">'
        f'{names.get(axis, axis)}<span>axis {axis}</span></div>'
        f'<div class="rungs">{"".join(rungs)}</div></div>'
    )


def render_threat(rows: list[list[str]]) -> str:
    head = "".join(f"<th>{inline(c)}</th>" for c in rows[0])
    body = []
    for cells in rows[1:]:
        tds = [f"<td>{inline(cells[0])}</td>"]
        for c in cells[1:]:
            cls = "yes" if "✓" in c else "no" if "✗" in c else ""
            tds.append(f'<td class="{cls}">{inline(c)}</td>')
        body.append(f"<tr>{''.join(tds)}</tr>")
    return (f'<div class="scroll"><table class="tm"><thead><tr>{head}</tr></thead>'
            f'<tbody>{"".join(body)}</tbody></table></div>')


def render_matrix(rows: list[list[str]]) -> str:
    """`E \\ P` table becomes the two-axis grid. Cells hold pins or markers."""
    cols = rows[0][1:]
    cells = ['<div class="mgrid">']
    for cells_row in rows[1:]:
        e = cells_row[0].strip("*")
        level = int(e[1]) if len(e) > 1 and e[1].isdigit() else 0
        cells.append(f'<div class="rlab">{html.escape(e)}</div>')
        for value in cells_row[1:]:
            v = value.strip()
            if v == "—":
                cells.append('<div class="mcell void"></div>')
                continue
            tint = f" tint{level}" if level else ""
            pins = ""
            for entry in (p.strip() for p in v.split("<br>") if p.strip()):
                ghost = " ghost" if entry.startswith("(") else ""
                pins += f'<span class="pin{ghost}">{inline(entry.strip("()"))}</span>'
            cells.append(f'<div class="mcell{tint}">{pins}</div>')
    cells.append('<div class="rlab"></div>')
    cells.extend(f'<div class="clab">{html.escape(c)}</div>' for c in cols)
    cells.append("</div>")
    return (
        '<div class="matrix-shell"><div class="ylab">Enforcement →</div>'
        + "".join(cells)
        + "</div>"
        '<div class="mnote">'
        '<span class="k"><span class="sw"></span>Where a service sits today</span>'
        '<span class="k"><span class="sw g"></span>Target or default</span>'
        '<span class="k"><span class="sw v"></span>Unreachable at this placement</span>'
        "</div>"
    )


def render_table(rows: list[list[str]]) -> str:
    if not rows:
        return ""
    header = [c.strip() for c in rows[0]]
    first = header[0].lower()
    if first.replace(" ", "") in {"e\\p", "e\\p"}:
        return render_matrix(rows)
    if first == "threat":
        return render_threat(rows)
    kind_col = header.index("Kind") if "Kind" in header else None
    # A level table is a ladder. The evidence table also leads with `Level` but
    # carries a `Kind` column, and is a table of artifacts, not of rungs.
    if first == "level" and kind_col is None and len(rows) > 1 and LEVEL_CELL.match(rows[1][0]):
        return render_ladder(rows)
    head = "".join(f"<th>{inline(c)}</th>" for c in header)
    body = []
    for cells in rows[1:]:
        tds = []
        for i, c in enumerate(cells):
            if i == kind_col:
                adv = "adv" if "adversarial" in c.lower() else ""
                label = re.sub(r"[*_]", "", c).strip()
                tds.append(f'<td><span class="kind {adv}">{html.escape(label)}</span></td>')
            else:
                tds.append(f"<td>{inline(c)}</td>")
        body.append(f"<tr>{''.join(tds)}</tr>")
    return (f'<div class="scroll"><table><thead><tr>{head}</tr></thead>'
            f'<tbody>{"".join(body)}</tbody></table></div>')


# --- document ---------------------------------------------------------------


def render_body(markdown: str) -> tuple[str, list[tuple[str, str, str]]]:
    lines = markdown.splitlines()
    out: list[str] = []
    rail: list[tuple[str, str, str]] = []
    open_section = False
    ladders_open = False
    i = 0

    def close_ladders() -> None:
        nonlocal ladders_open
        if ladders_open:
            out.append("</div></div>")
            ladders_open = False

    while i < len(lines):
        line = lines[i]
        stripped = line.strip()

        if not stripped:
            i += 1
            continue

        heading = HEADING.match(stripped)
        if heading:
            level, text = len(heading.group(1)), heading.group(2)
            if level == 1:
                i += 1
                continue
            if level == 2:
                close_ladders()
                if open_section:
                    out.append("</section>")
                match = SECTION_NO.match(text)
                if match:
                    num, title = match.group(1), match.group(2)
                    anchor = f"s{num}"
                    rail.append((anchor, num, title))
                    out.append(
                        f'<section id="{anchor}"><h2>'
                        f'<span class="sn">{int(num):02d}</span>{inline(title)}</h2>'
                    )
                else:
                    anchor = re.sub(r"[^a-z0-9]+", "-", text.lower()).strip("-")
                    rail.append((anchor, "·", text))
                    out.append(f'<section id="{anchor}"><h2>{inline(text)}</h2>')
                open_section = True
            else:
                close_ladders()
                out.append(f"<h3>{inline(text)}</h3>")
            i += 1
            continue

        if stripped.startswith("|"):
            rows, i = parse_table(lines, i)
            rendered = render_table(rows)
            if 'class="ladder"' in rendered:
                if not ladders_open:
                    out.append('<div class="breakout"><div class="ladders">')
                    ladders_open = True
                out.append(rendered)
            else:
                close_ladders()
                out.append(rendered)
            continue

        close_ladders()

        if stripped.startswith("```"):
            block = []
            i += 1
            while i < len(lines) and not lines[i].strip().startswith("```"):
                block.append(lines[i])
                i += 1
            out.append(f"<pre>{html.escape(chr(10).join(block))}</pre>")
            i += 1
            continue

        if stripped.startswith(">"):
            quote = []
            while i < len(lines) and lines[i].strip().startswith(">"):
                quote.append(lines[i].strip().lstrip(">").strip())
                i += 1
            out.append(f'<div class="rule-quote"><p>{inline(" ".join(quote))}</p></div>')
            continue

        if re.match(r"^[-*]\s+", stripped) or re.match(r"^\d+\.\s+", stripped):
            ordered = bool(re.match(r"^\d+\.\s+", stripped))
            items = []
            while i < len(lines):
                s = lines[i].strip()
                if re.match(r"^[-*]\s+", s) or re.match(r"^\d+\.\s+", s):
                    items.append(re.sub(r"^([-*]|\d+\.)\s+", "", s))
                elif s and lines[i].startswith(("  ", "\t")) and items:
                    items[-1] += " " + s
                else:
                    break
                i += 1
            tag = "ol" if ordered else "ul"
            body = "".join(f"<li>{inline(t)}</li>" for t in items)
            out.append(f"<{tag}>{body}</{tag}>")
            continue

        if set(stripped) <= set("-") and len(stripped) >= 3:
            i += 1
            continue

        para = [stripped]
        i += 1
        while i < len(lines) and lines[i].strip() and not re.match(
            r"^(\||>|```|#{1,4}\s|[-*]\s|\d+\.\s|---)", lines[i].strip()
        ):
            para.append(lines[i].strip())
            i += 1
        text = " ".join(para)
        decision = DECISION.match(text)
        if decision:
            out.append(
                f'<p><span class="dec">{inline(decision.group(1))}</span>'
                f"{inline(decision.group(2))}</p>"
            )
        else:
            out.append(f"<p>{inline(text)}</p>")

    close_ladders()
    if open_section:
        out.append("</section>")
    return "\n".join(out), rail


def render_page(
    source: pathlib.Path,
    *,
    title: str | None = None,
    subtitle: str = "",
    publication: dict[str, str] | None = None,
) -> tuple[str, dict, int]:
    meta, markdown = split_frontmatter(source.read_text(encoding="utf-8"))
    body, rail = render_body(markdown)

    resolved_title = title or meta.get("title", source.stem)
    display = resolved_title.split(":")[0].strip()
    eyebrow = " ".join(
        f"<span{' class=\"stat\"' if k == 'status' else ''}>{html.escape(v)}</span>"
        for k, v in (
            ("id", meta.get("id", "")),
            ("status", f"{meta.get('status', '')} · {meta.get('revision', '')}".strip(" ·")),
            ("owner", meta.get("owner", "")),
            (
                "review",
                f"reviewed {meta.get('last_reviewed', '')}"
                if meta.get("last_reviewed")
                else "",
            ),
        )
        if v
    )
    rail_html = "".join(
        f'<li><a href="#{a}"><span class="n">{n}</span>{html.escape(t)}</a></li>'
        for a, n, t in rail
    )

    publication = publication or {}
    source_note = " · ".join(
        item
        for item in (
            publication.get("source_repo", ""),
            publication.get("source_path", ""),
            publication.get("source_revision", ""),
        )
        if item
    )
    source_line = (
        f'<p class="sub">Source: <code>{html.escape(source_note)}</code></p>'
        if source_note
        else ""
    )
    review_due = publication.get("review_due", "")
    review_line = (
        f'<p class="sub">Review due: {html.escape(review_due)}</p>'
        if review_due
        else ""
    )
    lifecycle = publication.get("lifecycle", "active")
    successor = publication.get("successor", "")
    lifecycle_notice = ""
    if lifecycle == "superseded":
        successor_link = (
            f' <a href="{html.escape(successor, quote=True)}">Read its successor.</a>'
            if successor
            else ""
        )
        lifecycle_notice = (
            '<div class="rule-quote"><p><strong>Superseded.</strong>'
            f" This address is retained as part of the policy record.{successor_link}</p></div>"
        )
    elif lifecycle == "withdrawn":
        lifecycle_notice = (
            '<div class="rule-quote"><p><strong>Withdrawn.</strong> '
            "This document is retained for historical reference and is not current policy."
            "</p></div>"
        )
    currency_notice = (
        '<div class="rule-quote"><p><strong>Review overdue.</strong> '
        f"This document was due for review on {html.escape(review_due)}.</p></div>"
        if review_due and publication.get("stale") == "true"
        else ""
    )
    source_revision_meta = (
        f'<meta name="policy-source-revision" content="'
        f'{html.escape(publication.get("source_revision", ""), quote=True)}">\n'
        if publication.get("source_revision")
        else ""
    )
    source_digest_meta = (
        f'<meta name="policy-source-digest" content="'
        f'{html.escape(publication.get("source_digest", ""), quote=True)}">\n'
        if publication.get("source_digest")
        else ""
    )
    page = (
        "<!doctype html>\n<html lang=\"en\"><meta charset=\"utf-8\">\n"
        + source_revision_meta
        + source_digest_meta
        + f"<title>{html.escape(display)}</title>\n"
        f"<style>\n{STYLE.read_text()}\n</style>\n"
        '<div class="wrap"><header>'
        f'<div class="eyebrow">{eyebrow}<span>generated from canonical source — do not edit</span></div>'
        f"<h1>{html.escape(display)}</h1>"
        + (f'<p class="sub">{html.escape(subtitle)}</p>' if subtitle else "")
        + source_line
        + review_line
        + '</header><div class="layout">'
        f'<nav class="rail" aria-label="Sections"><ol>{rail_html}</ol></nav>'
        f"<main>{lifecycle_notice}{currency_notice}{body}"
        f'<footer><span>{html.escape(meta.get("id", ""))} · '
        f'{html.escape(meta.get("revision", ""))} · {html.escape(meta.get("status", ""))}</span>'
        f"<span>{html.escape(source_note or 'generated from canonical source')}</span></footer>"
        "</main></div></div></html>\n"
    )
    return page, meta, len(rail)


def main() -> int:
    ap = argparse.ArgumentParser()
    ap.add_argument("source", type=pathlib.Path)
    ap.add_argument("--output", required=True, type=pathlib.Path)
    ap.add_argument("--title", default=None)
    ap.add_argument("--subtitle", default="")
    args = ap.parse_args()

    page, _meta, section_count = render_page(
        args.source,
        title=args.title,
        subtitle=args.subtitle,
    )
    args.output.parent.mkdir(parents=True, exist_ok=True)
    args.output.write_text(page, encoding="utf-8")
    print(f"{args.output}: {section_count} sections, {len(page)} bytes")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())