#!/usr/bin/env python3
"""Point Navop at a local `gpui-pre` snapshot instead of the crates.io one.

`gpui-pre-*` is a crates.io republication of Zed's gpui crates. gpui-component
cuts a fresh snapshot every week with its own `script/bump-gpui.ts`, which
copies the crates out of a Zed checkout, renames them (`gpui` -> `gpui-pre`,
`util` -> `gpui-pre-util`, ...) and rewrites them into a standalone workspace.

Navop needs the dynamic-texture API (`DynamicTexture`,
`Window::update_dynamic_texture`, ...) which only exists on Zed's
`dynamic-texture` branch, so this script runs that same pipeline against a
local Zed checkout and then rewrites the generated `[patch.crates-io]` block in
Navop's root `Cargo.toml` to point at the staged crates.

Why a path patch rather than a git patch: the staged snapshots carry the
`gpui-pre-*` package names and a version that satisfies Navop's `^0.3.1`
requirement, so `[patch.crates-io]` accepts them. A Zed checkout on its own
declares `gpui`/`util`/... at Zed's own versions and would never match.

The staged workspace has to live outside every Cargo workspace. Cargo resolves
`workspace = true` against the nearest ancestor manifest that owns the package
as a member, and a snapshot left under `gpui-component/target/` gets attributed
to gpui-component's workspace, which has no `accesskit`/`gpui_pre_*` entries to
inherit from. The pipeline's own verification hits the same problem and works
around it the same way: copy the staging somewhere neutral before pointing a
manifest at it. `<gpui-component>/../.gpui-pre/workspace` is that place — it sits
next to the two checkouts, inside no workspace and no repository.

Usage:
    script/patch-local-gpui-pre.py [options]

Options:
    --zed PATH          Zed checkout to snapshot (default: the `zed` checkout
                        next to the Navop and gpui-component checkouts)
    --component PATH    gpui-component checkout that owns the staging pipeline
                        (default: the `gpui-component` checkout next to Navop)
    --patch-dir PATH    Where to put the copy the patch points at (default:
                        `<gpui-component>/../.gpui-pre`)
    --version VERSION   Version to stamp on the staged crates; must satisfy the
                        `gpui-pre` requirement in Cargo.toml (default: 0.3.99)
    --no-stage          Reuse the workspace already staged, only refresh the
                        copy and the patch block
    --update-lock       Run `cargo update` for the patched crates so Cargo.lock
                        moves onto the snapshot (without it, Cargo keeps the
                        published version and ignores the patch)
    --remove            Delete the patch block and stop
    -h, --help          Show this help

Run it again whenever the local Zed branch changes: the patch paths stay the
same, only the staged sources are rebuilt.
"""

from __future__ import annotations

import argparse
import json
import os
import re
import shutil
import subprocess
import sys
from pathlib import Path

BEGIN_MARKER = "# >>> local gpui-pre patch (generated by script/patch-local-gpui-pre.py) >>>"
END_MARKER = "# <<< local gpui-pre patch <<<"

DEFAULT_VERSION = "0.3.99"
PUBLISH_PREFIX = "gpui-pre"


class Error(Exception):
    """A user-facing failure, printed without a traceback."""


def run(cmd: list[str], cwd: Path | None = None) -> None:
    print(f"$ {' '.join(cmd)}")
    result = subprocess.run(cmd, cwd=cwd)
    if result.returncode != 0:
        raise Error(f"command failed with exit code {result.returncode}: {' '.join(cmd)}")


def run_capture(cmd: list[str], cwd: Path | None = None) -> str:
    result = subprocess.run(cmd, cwd=cwd, capture_output=True, text=True)
    if result.returncode != 0:
        raise Error(f"command failed with exit code {result.returncode}: {' '.join(cmd)}")
    return result.stdout


def sibling(root: Path, name: str, marker: str, flag: str) -> Path:
    """Find a checkout next to the Navop root, at any of the nesting depths.

    Navop is normally checked out as `<workspace>/navop`, but the gpui-kit
    migration lives in `<workspace>/navop/.worktrees/gpui-kit`, one level
    deeper, so the sibling is two, three or four levels up.
    """
    for depth in range(1, 5):
        candidate = root
        for _ in range(depth):
            candidate = candidate.parent
        candidate = candidate / name
        if (candidate / marker).exists():
            return candidate.resolve()
    raise Error(
        f"could not find a {name} checkout next to {root}; pass {flag} PATH"
    )


def find_bun() -> str:
    """Locate the Bun runtime that runs the staging pipeline."""
    found = shutil.which("bun")
    if found:
        return found
    # A `npm install bun` under $HOME is a common fallback; it installs a shim
    # at ~/node_modules/.bin/bun.
    fallback = Path.home() / "node_modules" / ".bin" / "bun"
    if fallback.is_file():
        return str(fallback)
    raise Error(
        "bun is not installed; install it with `npm install -g bun` (or "
        "`brew install oven-sh/bun/bun`) and re-run"
    )


def stage(component: Path, zed: Path, version: str) -> Path:
    """Run gpui-component's snapshot pipeline into its `target/gpui-pre`."""
    script = component / "script" / "bump-gpui.ts"
    if not script.is_file():
        raise Error(f"{script} not found; is {component} a gpui-component checkout?")
    if not (zed / "Cargo.toml").is_file():
        raise Error(f"{zed} does not look like a Zed checkout (no Cargo.toml)")
    run(
        [
            find_bun(),
            str(script),
            version,
            "--zed",
            str(zed),
            "--stage-only",
        ],
        cwd=component,
    )
    workspace = component / "target" / "gpui-pre" / "workspace"
    if not (workspace / "Cargo.toml").is_file():
        raise Error(f"the pipeline did not write {workspace}")
    return workspace


def mirror(staged: Path, patch_dir: Path) -> Path:
    """Copy the staged workspace somewhere that belongs to no workspace.

    The staging under `gpui-component/target/` cannot be patched directly: Cargo
    would resolve its `workspace = true` keys against gpui-component's
    workspace, which knows nothing about `accesskit` or the `gpui-pre-*`
    packages themselves. A copy outside every checkout resolves against the
    staged root, as intended. `target/` is left behind — it is build output,
    not part of the snapshot.
    """
    destination = patch_dir / "workspace"
    if destination.exists():
        shutil.rmtree(destination)
    shutil.copytree(staged, destination, ignore=shutil.ignore_patterns("target"))
    return destination


def staged_crates(workspace: Path) -> list[tuple[str, Path]]:
    """Read the staged workspace's dependency table for published name -> dir.

    The pipeline lists every republished crate as
    `<alias> = { path = "...", package = "gpui-pre-...", version = "=..." }`,
    which is exactly the mapping the patch needs.
    """
    manifest = (workspace / "Cargo.toml").read_text()
    section = re.search(
        r"^\[workspace\.dependencies\]\s*$(.*?)(?=^\[|\Z)",
        manifest,
        re.MULTILINE | re.DOTALL,
    )
    if section is None:
        raise Error(f"{workspace / 'Cargo.toml'} has no [workspace.dependencies]")
    crates: list[tuple[str, Path]] = []
    for line in section.group(1).splitlines():
        if re.match(r"^\s*[\w-]+\s*=\s*\{", line) is None:
            continue
        package = re.search(r'\bpackage\s*=\s*"([^"]+)"', line)
        path = re.search(r'\bpath\s*=\s*"([^"]+)"', line)
        if package is None or path is None:
            continue
        name = package.group(1)
        if not name.startswith(PUBLISH_PREFIX):
            continue
        crates.append((name, (workspace / path.group(1)).resolve()))
    if not crates:
        raise Error(f"no {PUBLISH_PREFIX}-* crates found in {workspace / 'Cargo.toml'}")
    return sorted(set(crates))


def patch_block(manifest_dir: Path, crates: list[tuple[str, Path]]) -> str:
    width = max(len(name) for name, _ in crates)
    lines = [
        BEGIN_MARKER,
        "#",
        "# LOCAL ONLY: the published gpui-pre-* snapshot predates Zed's",
        "# dynamic-texture API. This redirects every gpui-pre-* crate at the local",
        "# Zed checkout that has it. Re-run script/patch-local-gpui-pre.py after",
        "# changing that branch; `--remove` deletes the block.",
        "[patch.crates-io]",
    ]
    lines += [
        f'{name.ljust(width)} = {{ path = "{os.path.relpath(path, manifest_dir)}" }}'
        for name, path in crates
    ]
    lines.append(END_MARKER)
    return "\n".join(lines) + "\n"


def rewrite_manifest(root: Path, block: str | None) -> None:
    manifest = root / "Cargo.toml"
    text = manifest.read_text()
    pattern = re.compile(
        rf"^{re.escape(BEGIN_MARKER)}$.*?^{re.escape(END_MARKER)}\n?",
        re.MULTILINE | re.DOTALL,
    )
    if block is None:
        if pattern.search(text) is None:
            print(f"{manifest} has no local gpui-pre patch; nothing to remove")
            return
        manifest.write_text(pattern.sub("", text).rstrip() + "\n")
        print(f"removed the local gpui-pre patch from {manifest}")
        return
    if pattern.search(text) is not None:
        manifest.write_text(pattern.sub(block, text))
    else:
        manifest.write_text(text.rstrip() + "\n\n" + block)
    print(f"wrote {len(block.splitlines()) - 6} patch entries to {manifest}")


def graph_crates(
    root: Path, crates: list[tuple[str, Path]]
) -> tuple[list[str], list[str]]:
    """Split the patched crates into those Navop resolves and those it does not.

    `cargo update -p` fails on a package that is not in the graph, and Cargo
    reports a patch that resolved to nothing as unused, so both lists are worth
    knowing. `cargo metadata` is the only authoritative answer: Cargo.lock keeps
    stale entries for packages the graph has dropped.
    """
    metadata = json.loads(
        run_capture(["cargo", "metadata", "--format-version", "1"], cwd=root)
    )
    resolved = {package["name"] for package in metadata["packages"]}
    used = [name for name, _ in crates if name in resolved]
    unused = [name for name, _ in crates if name not in resolved]
    return used, unused


def main(argv: list[str]) -> int:
    parser = argparse.ArgumentParser(
        description=__doc__,
        formatter_class=argparse.RawDescriptionHelpFormatter,
    )
    parser.add_argument("--zed")
    parser.add_argument("--component")
    parser.add_argument("--patch-dir")
    parser.add_argument("--version", default=DEFAULT_VERSION)
    parser.add_argument("--no-stage", action="store_true")
    parser.add_argument("--update-lock", action="store_true")
    parser.add_argument("--remove", action="store_true")
    args = parser.parse_args(argv)

    root = Path(__file__).resolve().parent.parent
    if args.remove:
        rewrite_manifest(root, None)
        return 0

    component = (
        Path(args.component).expanduser().resolve()
        if args.component
        else sibling(root, "gpui-component", "script/bump-gpui.ts", "--component")
    )
    zed = (
        Path(args.zed).expanduser().resolve()
        if args.zed
        else sibling(root, "zed", "crates/gpui/Cargo.toml", "--zed")
    )
    patch_dir = (
        Path(args.patch_dir).expanduser().resolve()
        if args.patch_dir
        else component.parent / ".gpui-pre"
    )

    staged = component / "target" / "gpui-pre" / "workspace"
    if not args.no_stage:
        staged = stage(component, zed, args.version)
    elif not (staged / "Cargo.toml").is_file():
        raise Error(f"--no-stage was given but {staged} is empty")

    workspace = mirror(staged, patch_dir)
    crates = staged_crates(workspace)
    rewrite_manifest(root, patch_block(root, crates))
    print(f"snapshot from {zed}")
    print(f"staged workspace: {staged}")
    print(f"patched workspace: {workspace}")
    print(f"{len(crates)} crates patched: {', '.join(name for name, _ in crates)}")

    # Cargo keeps a locked version when it still satisfies the requirement, so
    # a patch alone does not move Cargo.lock onto the snapshot.
    used, unused = graph_crates(root, crates)
    if unused:
        print(
            "not reached by Navop's graph, so Cargo will report them as unused "
            f"patches: {', '.join(unused)}"
        )
    if args.update_lock:
        packages = [arg for name in used for arg in ("-p", name)]
        run(["cargo", "update", *packages], cwd=root)
    else:
        print("run this to move Cargo.lock onto the snapshot, then rebuild:")
        print("    cargo update " + " ".join(f"-p {name}" for name in used))
    return 0


if __name__ == "__main__":
    try:
        sys.exit(main(sys.argv[1:]))
    except Error as error:
        print(f"error: {error}", file=sys.stderr)
        sys.exit(1)