#!/usr/bin/env python3
"""Render the versioned Mermaid architecture diagrams.

Reads ``*.mmd`` sources from a directory (``.serena/diagrams`` by
default) and writes a single browsable HTML index. With ``--format
svg`` or ``--format png`` it shells out to ``mmdc`` from
``@mermaid-js/mermaid-cli`` instead.

Examples::

    scripts/render-diagrams
    scripts/render-diagrams --format svg
    scripts/render-diagrams --diagram architecture-flow
"""

from __future__ import annotations

import argparse
import html
import shutil
import subprocess
import sys
from pathlib import Path

DEFAULT_SRC = Path(".serena/diagrams")
DEFAULT_MERMAID_VERSION = "11"
SOURCE_SUFFIXES = (".mmd", ".mermaid")


class RenderError(RuntimeError):
    """Raised when a diagram cannot be rendered."""


def discover_diagrams(src: Path, out: Path | None = None) -> list[Path]:
    """Return the diagram sources under ``src``, sorted by path.

    ``out``, when given, is skipped so a previous render is never read
    back as a source.
    """
    if not src.is_dir():
        return []

    ignored = out.resolve() if out is not None else None
    found: list[Path] = []
    for path in src.rglob("*"):
        if not path.is_file() or path.suffix.lower() not in SOURCE_SUFFIXES:
            continue
        if ignored is not None and ignored in path.resolve().parents:
            continue
        found.append(path)
    return sorted(found)


def filter_diagrams(diagrams: list[Path], names: list[str] | None) -> list[Path]:
    """Keep only the diagrams whose file stem is in ``names``."""
    if not names:
        return diagrams
    wanted = set(names)
    return [path for path in diagrams if path.stem in wanted]


def build_html(
    diagrams: list[Path],
    src: Path,
    mermaid_version: str = DEFAULT_MERMAID_VERSION,
) -> str:
    """Build a self-contained HTML index embedding every diagram source."""
    sections = []
    for path in diagrams:
        source = path.read_text(encoding="utf-8").strip()
        name = path.relative_to(src).as_posix()
        sections.append(
            f'<section class="diagram">\n'
            f"<h2>{html.escape(name)}</h2>\n"
            f'<pre class="mermaid">{html.escape(source)}</pre>\n'
            f"</section>"
        )

    body = "\n".join(sections) if sections else "<p>No diagrams found.</p>"
    return f"""<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Penpot architecture diagrams</title>
<style>
  :root {{ color-scheme: light dark; }}
  body {{ margin: 0; font-family: system-ui, sans-serif; background: #f5f6f8; color: #1c1d21; }}
  header {{ padding: 1.5rem 2rem; background: #1c1d21; color: #fff; }}
  header h1 {{ margin: 0; font-size: 1.25rem; }}
  main {{ padding: 1.5rem 2rem; display: grid; gap: 2rem; grid-template-columns: repeat(auto-fit, minmax(480px, 1fr)); }}
  .diagram {{ margin: 0; padding: 1.25rem; background: #fff; border: 1px solid #e0e2e8; border-radius: 10px; overflow: auto; }}
  .diagram h2 {{ margin: 0 0 .75rem; font-size: .9rem; font-weight: 600; color: #6a6d78; }}
  .mermaid {{ margin: 0; text-align: center; }}
</style>
</head>
<body>
<header><h1>Penpot architecture diagrams</h1></header>
<main>
{body}
</main>
<script type="module">
  import mermaid from "https://cdn.jsdelivr.net/npm/mermaid@{mermaid_version}/dist/mermaid.esm.min.mjs";
  mermaid.initialize({{ startOnLoad: true, theme: "neutral" }});
</script>
</body>
</html>
"""


def render(
    diagrams: list[Path],
    src: Path,
    out: Path,
    mode: str = "html",
    mermaid_version: str = DEFAULT_MERMAID_VERSION,
) -> list[Path]:
    """Render ``diagrams`` into ``out`` and return the produced files."""
    out.mkdir(parents=True, exist_ok=True)

    if mode == "html":
        index = out / "index.html"
        index.write_text(
            build_html(diagrams, src, mermaid_version), encoding="utf-8"
        )
        return [index]

    if shutil.which("mmdc") is None:
        raise RenderError(
            "mmdc not found. Install it with "
            "'pnpm add -D @mermaid-js/mermaid-cli', or use "
            "--format html."
        )

    produced = []
    for path in diagrams:
        stem = path.relative_to(src).with_suffix("").as_posix().replace("/", "_")
        target = out / f"{stem}.{mode}"
        subprocess.run(
            ["mmdc", "-i", str(path), "-o", str(target)],
            check=True,
        )
        produced.append(target)
    return produced


def main(argv: list[str] | None = None) -> int:
    parser = argparse.ArgumentParser(description=__doc__.splitlines()[0])
    parser.add_argument(
        "--src",
        type=Path,
        default=DEFAULT_SRC,
        help=f"directory with .mmd sources (default: {DEFAULT_SRC})",
    )
    parser.add_argument(
        "--out",
        type=Path,
        default=None,
        help="output directory (default: <src>/out)",
    )
    parser.add_argument(
        "--format",
        choices=("html", "svg", "png"),
        default="html",
        help="output format (default: html)",
    )
    parser.add_argument(
        "--diagram",
        action="append",
        default=None,
        metavar="NAME",
        help="render only this source stem (repeatable)",
    )
    parser.add_argument(
        "--mermaid-version",
        default=DEFAULT_MERMAID_VERSION,
        help=f"CDN Mermaid version for HTML (default: {DEFAULT_MERMAID_VERSION})",
    )
    args = parser.parse_args(argv)

    out = args.out if args.out is not None else args.src / "out"
    diagrams = filter_diagrams(discover_diagrams(args.src, out), args.diagram)

    if not diagrams:
        print(f"No diagrams found in {args.src}", file=sys.stderr)
        return 1

    try:
        produced = render(
            diagrams, args.src, out, args.format, args.mermaid_version
        )
    except (RenderError, subprocess.CalledProcessError) as error:
        print(f"error: {error}", file=sys.stderr)
        return 1

    for path in produced:
        print(path)
    return 0


if __name__ == "__main__":
    sys.exit(main())