"""Build the web Studio: the Studio GUI with the isokit engine compiled to WASM.

    python tools/build_web.py [--out dist/web] [--skip-cargo]

Needs rustup with the wasm32-unknown-unknown target (rustup target add
wasm32-unknown-unknown) and the wasm-bindgen CLI at the version in Cargo.lock.
rustup's cargo is used even when another Rust install comes first on PATH.
wasm-opt (binaryen) is used when it is on PATH. The output folder is static
files: serve it from any web server (it needs http(s), not file://).
"""
import argparse
import hashlib
import json
import os
import re
import shutil
import subprocess
import sys
from pathlib import Path

ROOT = Path(__file__).resolve().parent.parent
SKIP_DIRS = {"dist", "target", "node_modules"}
TARGET = "wasm32-unknown-unknown"

# rustup's bin folder first: a standalone Rust install earlier on PATH (one
# without the wasm target, e.g. "Rust stable GNU") must not win
CARGO_BIN = Path(os.environ.get("CARGO_HOME") or Path.home() / ".cargo") / "bin"
ENV = dict(os.environ)
if CARGO_BIN.is_dir():
    ENV["PATH"] = str(CARGO_BIN) + os.pathsep + ENV.get("PATH", "")


def tool(name):
    return shutil.which(name, path=ENV["PATH"])


def run(cmd, **kw):
    print("+", " ".join(str(c) for c in cmd), flush=True)
    subprocess.run([str(c) for c in cmd], check=True, cwd=ROOT, env=ENV, **kw)


def check_toolchain():
    """rustup with the wasm target, and wasm-bindgen at the locked version."""
    rustup = tool("rustup")
    if not rustup:
        sys.exit("rustup not found (https://rustup.rs): the WASM build needs rustup's toolchain")
    installed = subprocess.run([rustup, "target", "list", "--installed"], capture_output=True, text=True,
                               cwd=ROOT, env=ENV).stdout.split()
    if TARGET not in installed:
        sys.exit(f"the {TARGET} target is not installed: rustup target add {TARGET}")
    cargo = tool("cargo")
    if not cargo or Path(cargo).parent.resolve() != CARGO_BIN.resolve():
        sys.exit(f"cargo resolves to {cargo}, not rustup's in {CARGO_BIN}")
    want = lock_version("wasm-bindgen")
    exe = tool("wasm-bindgen")
    if not exe:
        sys.exit(f"wasm-bindgen CLI not found: cargo install wasm-bindgen-cli --version {want}")
    have = subprocess.run([exe, "--version"], capture_output=True, text=True, env=ENV).stdout.split()[-1]
    if have != want:
        sys.exit(f"wasm-bindgen CLI is {have}, Cargo.lock has {want}: cargo install wasm-bindgen-cli --version {want}")


def lock_version(name):
    lock = (ROOT / "Cargo.lock").read_text(encoding="utf-8")
    m = re.search(r'name = "%s"\nversion = "([^"]+)"' % re.escape(name), lock)
    return m.group(1) if m else None


def demo_files():
    """The demo project as the web Studio stores projects: path -> text."""
    base = ROOT / "examples" / "demo"
    out = {}
    for p in sorted(base.rglob("*")):
        rel = p.relative_to(base).as_posix()
        parts = rel.split("/")
        if p.is_dir() or any(s.startswith(".") or s in SKIP_DIRS for s in parts[:-1]):
            continue
        if p.suffix in (".rhai", ".toml", ".json") or p.name == "README.md":
            out[rel] = p.read_text(encoding="utf-8")
    assert "isokit.toml" in out, "examples/demo has no isokit.toml"
    return out


def replace_once(s, old, new):
    n = s.count(old)
    assert n == 1, f"studio/index.html: expected {old!r} once, found {n}"
    return s.replace(old, new)


def main():
    ap = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
    ap.add_argument("--out", default=str(ROOT / "dist" / "web"))
    ap.add_argument("--skip-cargo", action="store_true", help="reuse the last WASM build (front-end changes only)")
    a = ap.parse_args()
    out = Path(a.out).resolve()
    web = out / "assets" / "web"
    wasm = ROOT / "target" / "wasm32-unknown-unknown" / "web" / "isokit_wasm.wasm"

    if not a.skip_cargo:
        check_toolchain()
        run([tool("cargo"), "build", "-p", "isokit-wasm", "--target", TARGET, "--profile", "web"])
    elif not tool("wasm-bindgen"):
        sys.exit("wasm-bindgen CLI not found")

    if out.exists():
        shutil.rmtree(out)
    web.mkdir(parents=True)
    if not wasm.exists():
        sys.exit(f"{wasm} missing: run without --skip-cargo")
    run([tool("wasm-bindgen"), "--target", "web", "--no-typescript", "--remove-name-section",
         "--remove-producers-section", "--out-dir", web.as_posix(), wasm.as_posix()])
    bg = web / "isokit_wasm_bg.wasm"
    if tool("wasm-opt"):
        run([tool("wasm-opt"), "-Oz", "--all-features", bg.as_posix(), "-o", bg.as_posix()])
    else:
        print("  (wasm-opt not found: the .wasm stays unoptimised by binaryen, about 15% larger)")

    for src, dst in [("viewer/isokit-view.js", "viewer"), ("viewer/isokit-view.css", "viewer"),
                     ("studio/studio.js", "studio"), ("studio/studio.css", "studio"),
                     ("web/web.js", "web"), ("web/web.css", "web")]:
        (out / "assets" / dst).mkdir(parents=True, exist_ok=True)
        shutil.copy2(ROOT / src, out / "assets" / dst / Path(src).name)
    (web / "demo.json").write_text(json.dumps(demo_files(), ensure_ascii=False), encoding="utf-8")

    h = hashlib.sha256()
    for p in sorted((out / "assets").rglob("*")):
        if p.is_file():
            h.update(p.read_bytes())
    v = "v=" + h.hexdigest()[:10]

    html = (ROOT / "studio" / "index.html").read_text(encoding="utf-8")
    html = replace_once(html, '<title>isokit Studio</title>',
                        '<title>isokit Studio</title>\n<meta name="description" content="isokit Studio: edit isometric site plans in the browser.">')
    html = replace_once(html, 'href="/assets/viewer/isokit-view.css"', f'href="assets/viewer/isokit-view.css?{v}"')
    html = replace_once(html, '<link rel="stylesheet" href="/assets/theme.css">', '<style id="iso-theme"></style>')
    html = replace_once(html, '<link rel="stylesheet" href="/assets/studio/studio.css">',
                        f'<link rel="stylesheet" href="assets/studio/studio.css?{v}">\n<link rel="stylesheet" href="assets/web/web.css?{v}">')
    html = replace_once(html, 'href="/view"', 'href="#"')
    html = replace_once(html, '<script src="/assets/viewer/isokit-view.js"></script>', f'<script src="assets/viewer/isokit-view.js?{v}"></script>')
    html = replace_once(html, '<script src="/assets/studio/studio.js"></script>',
                        f'<script type="module" src="assets/web/web.js?{v}"></script>\n'
                        '<noscript>The isokit Studio needs JavaScript and WebAssembly.</noscript>')
    assert "/assets/" not in html, "an absolute /assets/ URL is left in index.html"
    (out / "index.html").write_text(html, encoding="utf-8")

    total = 0
    for p in sorted(out.rglob("*")):
        if p.is_file():
            total += p.stat().st_size
            print(f"  {p.relative_to(out).as_posix():40} {p.stat().st_size / 1024:8.1f} kB")
    print(f"{out} ({total / 1024 / 1024:.1f} MB, {v})")


if __name__ == "__main__":
    main()