#!/usr/bin/env python3
"""Re-apply IDS-local patches to the vendored reveal.js bundle.

Run after every reveal.js update (see tools/update-reveal.R):

    python3 tools/patch-revealjs.py

Every patch is an exact-string replacement keyed to the minified upstream
code. If a newer reveal.js refactors the surroundings, the script fails
loudly instead of skipping silently -- port the patch by hand, then update
the pattern here. Safe to run repeatedly (already-applied patches are
detected and skipped).
"""
import sys
from pathlib import Path

REPO = Path(__file__).resolve().parent.parent

# Patch name -> [(upstream snippet, patched snippet), ...]
PATCHES = {
    # Upstream toggles the help overlay only on the US-layout keyCodes for '?'
    # (63/191) + shift, and an earlier modifier guard swallows unknown keyCodes
    # held with shift outright. On e.g. a German layout ('?' = Shift+ss) Chrome
    # reports neither keyCode, so '?' never opened the help screen there.
    # Match the produced character (event.key) instead; F1 keeps working.
    "help overlay on non-US keyboard layouts ('?' via event.key)": [
        (
            'l=!(-1!==[32,37,38,39,40,63,78,80,191].indexOf(e.keyCode)&&e.shiftKey||e.altKey)&&(e.shiftKey||e.altKey||e.ctrlKey||e.metaKey)',
            'l=!(-1!==[32,37,38,39,40,63,78,80,191].indexOf(e.keyCode)&&e.shiftKey||e.altKey)&&(e.shiftKey||e.altKey||e.ctrlKey||e.metaKey)&&"?"!==e.key',
        ),
        (
            ':63!==i&&191!==i||!e.shiftKey?112===i?this.Reveal.toggleHelp():u=!1:this.Reveal.toggleHelp())',
            ':"?"!==e.key&&(!e.shiftKey||63!==i&&191!==i)?112===i?this.Reveal.toggleHelp():u=!1:this.Reveal.toggleHelp())',
        ),
    ],
}


def main():
    bundles = sorted((REPO / "inst").glob("reveal.js-*/dist/reveal.js"))
    if len(bundles) != 1:
        sys.exit(f"expected exactly one vendored reveal.js, found: {bundles}")
    path = bundles[0]
    original = src = path.read_text()

    for name, pairs in PATCHES.items():
        for old, new in pairs:
            if new in src:
                print(f"already applied: {name}")
            elif old in src:
                src = src.replace(old, new, 1)
                print(f"applied:         {name}")
            else:
                sys.exit(
                    f"UPSTREAM CHANGED -- cannot locate pattern for patch:\n"
                    f"  {name}\n"
                    f"  missing snippet starts with: {old[:70]}...\n"
                    f"Port the patch by hand, then update tools/patch-revealjs.py."
                )

    if src != original:
        path.write_text(src)
        print(f"written: {path}")
    else:
        print("nothing to do")


if __name__ == "__main__":
    main()