m3e-canvas/scripts/apply-host.py

#!/usr/bin/env python3
"""
Wire the host adapter into the vendored editor.

Run by `vendor.sh` immediately after the import rewrite, so `web/vendor/` becomes a faithful copy of
upstream plus exactly this and nothing else.

── Why a script and not a .patch ──

Upstream moves fast and reformats. Between `cfde698` and `5c83ac6`, one day apart, the i18n import
line changed AND the whole component was re-indented from 6 spaces to 8 AND an `editAccess` guard
appeared. A context diff would have failed on all three, none of which have anything to do with us.

So every anchor here matches on STRUCTURE with flexible whitespace, and re-indents its replacement to
whatever it found. When an anchor genuinely disappears the script stops with the file and the thing
it wanted — loudly, because a silent mis-wire is the failure that matters.

What it wires is what upstream said a complete version needs (lnkiai/m3e-canvas#56): the host hooks,
in ALL THREE export paths rather than one.

── Three, and not the other two ──

A scan for `clipboard.writeText` finds FIVE call sites. Two of them are in `ShareMenu.tsx`, which
upstream added after the review, and they are deliberately NOT wired:

  copyAsk   an "ask an AI" blurb containing a guide URL and the user's one-line idea
  copyLink  a share link to the design

Neither is the generated prompt, so neither belongs behind `onExport`. This is written down because
the count looks wrong at a glance, and the previous round of this work was rejected for wiring one
path out of three — the next person to run that scan should not have to re-derive which is which.
"""
import re
import sys
from pathlib import Path

VENDOR = Path(__file__).resolve().parent.parent / "web" / "vendor"


def fail(what: str, where: str) -> None:
    raise SystemExit(
        f"\n  Could not find {what} in {where}.\n"
        f"  Upstream has moved underneath this script. Read the file, re-anchor, and re-run.\n"
        f"  This failing is the point — it is how a silent mis-wire is avoided.\n"
    )


def reindent(block: str, pad: str) -> str:
    """Re-indent a replacement to sit at the indentation actually found in the file."""
    lines = block.split("\n")
    return "\n".join(pad + l if l.strip() else l for l in lines)


def sub_once(src: str, pattern: str, build, what: str, where: str, flags=0) -> str:
    match = re.search(pattern, src, flags)
    if not match:
        fail(what, where)
    pad = re.match(r"[ \t]*", match.group(0)).group(0)
    return src[: match.start()] + build(match, pad) + src[match.end() :]


def add_import(src: str, spec: str, where: str) -> str:
    lines = src.split("\n")
    idx = [i for i, l in enumerate(lines) if l.startswith("import ")]
    if not idx:
        fail("any import statement", where)
    lines.insert(idx[-1] + 1, spec)
    return "\n".join(lines)


# ── Canvas.tsx ────────────────────────────────────────────────────────────────────────────────────

def canvas(src: str, name: str) -> str:
    src = add_import(src, 'import { useHost } from "./lib/host";', name)

    src = sub_once(
        src,
        r"[ \t]*export default function Page\(\) \{",
        lambda m, pad: m.group(0)
        + f"\n{pad}  // Optional host hooks; every default is the standalone behaviour. See lib/host.ts."
        + f"\n{pad}  const host = useHost();",
        "the component entry point",
        name,
    )

    src = sub_once(
        src,
        r"([ \t]*)const d = localStorage\.getItem\(DOC_KEY\);\n[ \t]*if \(d\) \{",
        lambda m, pad: reindent(
            '// Branch on whether the host SUPPLIED a loader, not on what it returned: a host\n'
            '// returning null means "no saved document", which must start fresh rather than\n'
            "// fall back to this browser's standalone copy. Raised on lnkiai/m3e-canvas#56.\n"
            "const hosted = host.loadDoc ? host.loadDoc() : null;\n"
            "const d = host.loadDoc ? null : localStorage.getItem(DOC_KEY);\n"
            "if (hosted) {\n"
            "  hadDocRef.current = true;\n"
            "  applyDoc(hosted, false);\n"
            "} else if (d) {",
            pad,
        ).lstrip(),
        "the document read",
        name,
    )

    src = sub_once(
        src,
        r"([ \t]*)const u = localStorage\.getItem\(UI_KEY\);\n[ \t]*if \(u\) \{\n[ \t]*const ui = JSON\.parse\(u\);",
        lambda m, pad: reindent(
            "const stored = host.loadUi ? null : localStorage.getItem(UI_KEY);\n"
            "const ui = host.loadUi ? host.loadUi() : stored ? JSON.parse(stored) : null;\n"
            "if (ui) {",
            pad,
        ).lstrip(),
        "the UI read",
        name,
    )

    src = sub_once(
        src,
        r"([ \t]*)localStorage\.setItem\(\s*DOC_KEY,\s*JSON\.stringify\((\{[^{}]*\})\),?\s*\);",
        lambda m, pad: reindent(
            f"const payload = {m.group(2)};\n"
            "if (host.saveDoc) host.saveDoc(payload as Partial<Doc>);\n"
            "else localStorage.setItem(DOC_KEY, JSON.stringify(payload));",
            pad,
        ).lstrip(),
        "the document write",
        name,
        re.S,
    )

    src = sub_once(
        src,
        r"([ \t]*)localStorage\.setItem\(\s*UI_KEY,\s*JSON\.stringify\((\{[^{}]*\})\),?\s*\);",
        lambda m, pad: reindent(
            "const ui = {%s};\n" % " ".join(m.group(2)[1:-1].split())
            + "if (host.saveUi) host.saveUi(ui);\n"
            "else localStorage.setItem(UI_KEY, JSON.stringify(ui));",
            pad,
        ).lstrip(),
        "the UI write",
        name,
        re.S,
    )

    return sub_once(
        src,
        r"([ \t]*)await navigator\.clipboard\.writeText\(effectivePrompt\(doc, widths, lang\)\);",
        lambda m, pad: reindent(
            "const text = effectivePrompt(doc, widths, lang);\n"
            "// The hook's own failure is isolated: a broken host must not also break copying.\n"
            "let handled = false;\n"
            "try { handled = host.onExport?.(text, doc) === true; } catch {}\n"
            "if (handled) return;\n"
            "await navigator.clipboard.writeText(text);",
            pad,
        ).lstrip(),
        "the toolbar export (1 of 3)",
        name,
    )


# ── the other two export paths ────────────────────────────────────────────────────────────────────

def prompt_panel(src: str, name: str) -> str:
    src = add_import(src, 'import { useHost } from "../lib/host";', name)
    src = sub_once(
        src,
        r"[ \t]*const \[copied, setCopied\] = useState\(false\);",
        lambda m, pad: f"{pad}const host = useHost();\n" + m.group(0),
        "the copied state",
        name,
    )
    return sub_once(
        src,
        r"([ \t]*)await navigator\.clipboard\.writeText\(text\);",
        lambda m, pad: reindent(
            "let handled = false;\n"
            "try { handled = host.onExport?.(text, null) === true; } catch {}\n"
            "if (handled) { setCopied(true); return; }\n"
            "await navigator.clipboard.writeText(text);",
            pad,
        ).lstrip(),
        "the copy call (2 of 3)",
        name,
    )


def inspector(src: str, name: str) -> str:
    src = add_import(src, 'import { useHost } from "../lib/host";', name)
    # The hook belongs to whichever component owns `prompt`; it is taken beside the copied state.
    src = sub_once(
        src,
        r"[ \t]*const \[copied, setCopied\] = useState\(false\);",
        lambda m, pad: f"{pad}const host = useHost();\n" + m.group(0),
        "the copied state",
        name,
    )
    return sub_once(
        src,
        r"([ \t]*)await navigator\.clipboard\.writeText\(prompt\);",
        lambda m, pad: reindent(
            "let handled = false;\n"
            "try { handled = host.onExport?.(prompt, null) === true; } catch {}\n"
            "if (handled) { setCopied(true); return; }\n"
            "await navigator.clipboard.writeText(prompt);",
            pad,
        ).lstrip(),
        "the export copy call (3 of 3)",
        name,
    )


def main() -> int:
    if not VENDOR.exists():
        raise SystemExit("web/vendor/ is missing — run scripts/vendor.sh first.")

    # `lib/host.ts` is OURS, not upstream's — upstream declined it. The canonical copy is
    # `web/host.ts`, edited like any other file we own; this places it where the vendored code's
    # imports expect it. Without this step `vendor.sh` leaves those imports dangling, because it
    # wipes the directory before copying.
    source = VENDOR.parent / "host.ts"
    if not source.exists():
        raise SystemExit("web/host.ts is missing — it is the source for the vendored lib/host.ts.")
    # One line is rewritten on the way in. `web/host.ts` is edited where it lives, so it imports
    # `./vendor/lib/tokens` — which is correct there and wrong once placed a directory deeper.
    # Deterministic, like vendor.sh own import rewrite, and it keeps the canonical copy typecheckable
    # instead of permanently carrying an unresolvable import for the sake of its destination.
    placed = source.read_text(encoding="utf-8").replace('"./vendor/lib/tokens"', '"./tokens"')
    if '"./tokens"' not in placed:
        fail("the tokens import to rewrite", "web/host.ts")

    # Marked like the rest of the vendored tree, because this step runs AFTER vendor.sh has marked it
    # and writes the file whole — so without this line the mark is lost on every re-vendor and this one
    # file starts failing the typecheck again. The canonical copy at web/host.ts stays checked; only
    # the placed copy is exempt, for the same reason its neighbours are.
    if not placed.startswith("// @ts-nocheck"):
        placed = "// @ts-nocheck — vendored, see PROVENANCE.md\n" + placed

    (VENDOR / "lib" / "host.ts").write_text(placed, encoding="utf-8")
    print("  placed lib/host.ts (ours)")
    for rel, fn in (
        ("Canvas.tsx", canvas),
        ("components/PromptPanel.tsx", prompt_panel),
        ("components/Inspector.tsx", inspector),
    ):
        path = VENDOR / rel
        path.write_text(fn(path.read_text(encoding="utf-8"), rel), encoding="utf-8")
        print(f"  wired {rel}")
    print("  all three export paths wired")
    return 0


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