#!/usr/bin/env python3
"""
Rendert alle @startuml ... @enduml Bloecke aus arch/**/*.md als SVG.

Verwendet einen erreichbaren PlantUML-HTTP-Server (Default: www.plantuml.com).
In CI kann die Server-URL ueber PLANTUML_SERVER ueberschrieben werden.

Output: docs/diagrams/<file>-<index>.svg

Run:
  python3 tools/render_plantuml.py
  PLANTUML_SERVER=http://plantuml-server:8080 python3 tools/render_plantuml.py
"""
from __future__ import annotations

import os
import re
import sys
import urllib.request
import zlib
from pathlib import Path

REPO = Path(__file__).resolve().parent.parent
SERVER = os.environ.get("PLANTUML_SERVER", "https://www.plantuml.com/plantuml")

# Map standard base64 to PlantUML's base64 alphabet
_B64 = (
    "0123456789"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "-_"
)


def _encode_3bytes(b1: int, b2: int, b3: int) -> str:
    c1 = b1 >> 2
    c2 = ((b1 & 0x3) << 4) | (b2 >> 4)
    c3 = ((b2 & 0xF) << 2) | (b3 >> 6)
    c4 = b3 & 0x3F
    return _B64[c1] + _B64[c2] + _B64[c3] + _B64[c4]


def plantuml_encode(text: str) -> str:
    """Encode PlantUML source to its URL-safe representation."""
    compressed = zlib.compress(text.encode("utf-8"), 9)
    # Strip zlib header (2 bytes) and Adler32 trailer (4 bytes)
    raw = compressed[2:-4]
    out = ""
    i = 0
    while i < len(raw):
        b1 = raw[i]
        b2 = raw[i + 1] if i + 1 < len(raw) else 0
        b3 = raw[i + 2] if i + 2 < len(raw) else 0
        out += _encode_3bytes(b1, b2, b3)
        i += 3
    return out


BLOCK_RE = re.compile(r"```plantuml\s*\n(@startuml.*?@enduml)\s*\n```",
                      re.DOTALL)


def extract_blocks(md: Path) -> list[str]:
    return BLOCK_RE.findall(md.read_text())


def render_one(src: str, out_path: Path) -> None:
    encoded = plantuml_encode(src)
    url = f"{SERVER.rstrip('/')}/svg/{encoded}"
    req = urllib.request.Request(url, headers={"User-Agent": "demo-epb/1.0"})
    with urllib.request.urlopen(req, timeout=30) as resp:
        data = resp.read()
    out_path.parent.mkdir(parents=True, exist_ok=True)
    out_path.write_bytes(data)


def main() -> int:
    out_dir = REPO / "docs" / "diagrams"
    out_dir.mkdir(parents=True, exist_ok=True)

    md_files = sorted((REPO / "arch").rglob("*.md"))
    if not md_files:
        print("Keine arch/**/*.md gefunden.")
        return 0

    total = 0
    for md in md_files:
        rel = md.relative_to(REPO)
        blocks = extract_blocks(md)
        if not blocks:
            continue
        for i, block in enumerate(blocks, start=1):
            stem = md.stem
            target = out_dir / f"{stem}-{i}.svg"
            try:
                render_one(block, target)
                print(f"  {rel} block {i} -> {target.relative_to(REPO)}")
                total += 1
            except Exception as e:
                print(f"  WARN: {rel} block {i} render failed: {e}")
    print(f"\nDone: {total} Diagrams rendered to {out_dir.relative_to(REPO)}/")
    return 0


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