Fry3DX/android/build_apk.py

#!/usr/bin/env python3
"""Builds Fry3DX's Android APK (arm64, Vulkan) with no Gradle: the NDK build (cmake --preset
android), the content as plain files in assets/, SDL's Java layer, the icon, then aapt2, d8,
zipalign and apksigner.

    nix-shell android/shell.nix --run "python3 android/build_apk.py [--install]"

Out: dist/Fry3DX-<version>-android-arm64.apk. --install puts it on a phone over adb (USB
debugging on) and starts it. The first start copies the content out (a moment).
Signed with ~/.local/share/Nexoniarz/Fry3DX-signing/release.keystore (made the first time),
or the key in $FRY_KEYSTORE / $FRY_KEYSTORE_PASS. Keep it safe and keep using it: Android only
updates an app signed with the key it was installed with.
"""
import os
import secrets
import shutil
import subprocess
import sys
import time
import zipfile

ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), ".."))
BUILD = os.path.join(ROOT, "build", "android")
APP = "Fry3DX"
PACKAGE = "io.github.nexoniarz.fry3dx"


def run(*cmd, **kw):
    subprocess.run(list(cmd), check=True, **kw)


def app_version():
    with open(os.path.join(ROOT, "CMakeLists.txt")) as f:
        for line in f:
            if line.startswith("project(Fry3DX VERSION "):
                return line.split()[2]
    return "0"


def main():
    sdk, ndk = os.environ["ANDROID_HOME"], os.environ["ANDROID_NDK_ROOT"]
    tools = os.path.join(sdk, "build-tools", "35.0.0")
    android_jar = os.path.join(sdk, "platforms", "android-35", "android.jar")
    llvm = os.path.join(ndk, "toolchains", "llvm", "prebuilt", "linux-x86_64", "bin")

    if not os.path.isdir(BUILD):
        glslc = os.environ.get("GLSLC") or os.path.join(ndk, "shader-tools", "linux-x86_64", "glslc")  # (the NDK's own, if none's given)
        run("cmake", "--preset", "android", *([f"-DGLSLC={glslc}"] if os.path.exists(glslc) else []), cwd=ROOT)
    run("cmake", "--build", "--preset", "android", cwd=ROOT)

    stage = os.path.join(BUILD, "apk")
    shutil.rmtree(stage, ignore_errors=True)
    assets, libs = os.path.join(stage, "assets"), os.path.join(stage, "lib", "arm64-v8a")
    os.makedirs(libs)
    bin_dir = os.path.join(BUILD, "bin")
    sdl = os.path.join(BUILD, "_deps", "sdl3-build", "libSDL3.so")
    for src in (os.path.join(bin_dir, "libmain.so"), sdl):
        run(os.path.join(llvm, "llvm-strip"), "--strip-debug", "-o", os.path.join(libs, os.path.basename(src)), src)

    # Content: the folders next to the program on a desktop, and the list it unpacks from (a
    # version on its first line, so an update unpacks again).
    for d in ("engine", APP):
        shutil.copytree(os.path.join(bin_dir, d), os.path.join(assets, d))
    commit = subprocess.run(["git", "rev-parse", "--short", "HEAD"], cwd=ROOT, capture_output=True, text=True).stdout.strip() or "local"
    version = f"{app_version()}-{commit}"
    files = [os.path.relpath(os.path.join(r, n), assets).replace(os.sep, "/") for r, _, ns in os.walk(assets) for n in ns]
    with open(os.path.join(assets, "content.txt"), "w") as f:
        f.write(f"{version}-{int(time.time())}\n" + "\n".join(sorted(files)) + "\n")

    # Java: SDL's activity and helpers, and ours on top; then dex.
    java_src = [os.path.join(ROOT, "android", "java"), os.path.join(BUILD, "_deps", "sdl3-src", "android-project", "app", "src", "main", "java")]
    sources = [os.path.join(r, n) for d in java_src for r, _, ns in os.walk(d) for n in ns if n.endswith(".java")]
    classes = os.path.join(BUILD, "java-classes")
    shutil.rmtree(classes, ignore_errors=True)
    os.makedirs(classes)
    print(f"Compiling {len(sources)} Java files")
    run("javac", "-nowarn", "-source", "8", "-target", "8", "-bootclasspath", android_jar, "-d", classes, *sources,
        stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
    class_files = [os.path.join(r, n) for r, _, ns in os.walk(classes) for n in ns if n.endswith(".class")]
    run(os.path.join(tools, "d8"), "--release", "--min-api", "28", "--lib", android_jar, "--output", stage, *class_files)

    # Resources (the icon), the manifest and the assets; then dex and libraries; aligned, signed.
    res_zip = os.path.join(BUILD, "res.zip")
    run(os.path.join(tools, "aapt2"), "compile", "--dir", os.path.join(ROOT, "android", "res"), "-o", res_zip)
    unsigned = os.path.join(BUILD, "unsigned.apk")
    vcode = str(int(time.time()) // 60 % 2000000000)
    run(os.path.join(tools, "aapt2"), "link", "-o", unsigned, "-I", android_jar, "--manifest", os.path.join(ROOT, "android", "AndroidManifest.xml"),
        "-A", assets, "-R", res_zip, "--auto-add-overlay", "--min-sdk-version", "28", "--target-sdk-version", "35",
        "--version-code", vcode, "--version-name", version)
    with zipfile.ZipFile(unsigned, "a") as z:
        z.write(os.path.join(stage, "classes.dex"), "classes.dex")
        for n in os.listdir(libs):
            z.write(os.path.join(libs, n), f"lib/arm64-v8a/{n}")
    aligned = os.path.join(BUILD, "aligned.apk")
    run(os.path.join(tools, "zipalign"), "-p", "-f", "4", unsigned, aligned)
    keystore = os.environ.get("FRY_KEYSTORE") or os.path.expanduser("~/.local/share/Nexoniarz/Fry3DX-signing/release.keystore")
    pass_file = keystore + ".pass"  # (its password, beside it, when made here)
    password = os.environ.get("FRY_KEYSTORE_PASS") or (open(pass_file).read().strip() if os.path.exists(pass_file) else "")
    if not os.path.exists(keystore):
        os.makedirs(os.path.dirname(keystore), exist_ok=True)
        password = password or secrets.token_urlsafe(24)
        with open(os.open(pass_file, os.O_WRONLY | os.O_CREAT | os.O_TRUNC, 0o600), "w") as f:
            f.write(password + "\n")
        run("keytool", "-genkeypair", "-keystore", keystore, "-storepass", password, "-keypass", password, "-alias", "fry3dx",
            "-keyalg", "RSA", "-keysize", "2048", "-validity", "10000", "-dname", "CN=Fry3DX", stdout=subprocess.DEVNULL)
    os.makedirs(os.path.join(ROOT, "dist"), exist_ok=True)
    out = os.path.join(ROOT, "dist", f"{APP}-{app_version()}-android-arm64.apk")
    run(os.path.join(tools, "apksigner"), "sign", "--ks", keystore, "--ks-pass", f"pass:{password}", "--out", out, aligned)
    print(f"{os.path.relpath(out, ROOT)}: {os.path.getsize(out) // (1024 * 1024)} MB")
    if "--install" in sys.argv:
        run("adb", "install", "-r", out)
        run("adb", "shell", "am", "start", "-n", f"{PACKAGE}/.FryActivity")


if __name__ == "__main__":
    main()