//! `cargo xtask apk` -- E5 (RUST.md): packages `app/shellApp` into a
//! signed, installable APK with no Gradle in the packaging step itself.
//! `cargo ndk` cross-compiles `android-shell`; `javac`/`d8` turn its two
//! Java stub classes (plus the generated pinned-CA constant) into dex;
//! `aapt2` compiles the manifest into `resources.arsc`; the dex and native
//! libraries are merged into that base APK with `jar`; `zipalign` and
//! `apksigner` finish it. See `apk.rs`'s module doc for what "no Gradle in
//! the packaging step" does and does not cover -- one disclosed exception.
//!
//! Usage: `cargo xtask apk [--release|--debug] [--abi ABI]...`

mod apk;
mod keystore;
mod sdk;

use std::fmt;
use std::process::ExitCode;

/// A failure a person acts on: what went wrong, what this process actually
/// saw, and the next thing to try. Matches CODE_RULES's "a failure message
/// names the thing, the cause, and the fix."
pub struct Fail {
    what: String,
    cause: String,
    fix: String,
}

impl Fail {
    pub fn new(what: &str, cause: &str, fix: &str) -> Self {
        Fail {
            what: what.to_string(),
            cause: cause.to_string(),
            fix: fix.to_string(),
        }
    }
}

impl fmt::Display for Fail {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            f,
            "{}\n  cause: {}\n  fix:   {}",
            self.what, self.cause, self.fix
        )
    }
}

#[derive(Clone, Copy, PartialEq, Eq)]
pub enum Variant {
    /// Signed with `~/.config/ai-app/release.jks`, the same key
    /// `build-apk.sh` uses for `androidApp` -- what E5's pass condition
    /// needs, since installing over an existing app requires a matching
    /// signature.
    Release,
    /// Signed with the standard Android debug keystore
    /// (`~/.android/debug.keystore`, well-known password, generated if
    /// missing the same way Gradle would), for a fast local loop that
    /// doesn't touch the real signing key.
    Debug,
}

fn main() -> ExitCode {
    let args: Vec<String> = std::env::args().skip(1).collect();
    let Some(("apk", rest)) = args.split_first().map(|(cmd, rest)| (cmd.as_str(), rest)) else {
        eprintln!("usage: cargo xtask apk [release|debug] [--abi ABI]...");
        return ExitCode::FAILURE;
    };

    let mut variant = Variant::Release;
    let mut abis: Vec<String> = Vec::new();
    let mut i = 0;
    while i < rest.len() {
        match rest[i].as_str() {
            // Bare "release"/"debug" is `.dev-updater.ron`'s interface
            // (`ByMode::One` appends the chosen mode as the build
            // command's last argument -- the same convention
            // `app/build-apk.sh`'s `${1:-release}` uses); the `--`-prefixed
            // spellings are for typing this by hand.
            "release" | "--release" => variant = Variant::Release,
            "debug" | "--debug" => variant = Variant::Debug,
            "--abi" => {
                i += 1;
                match rest.get(i) {
                    Some(abi) => abis.push(abi.clone()),
                    None => {
                        eprintln!("--abi needs a value (e.g. arm64-v8a, x86_64)");
                        return ExitCode::FAILURE;
                    }
                }
            }
            other => {
                eprintln!("unknown argument: {other}");
                return ExitCode::FAILURE;
            }
        }
        i += 1;
    }
    if abis.is_empty() {
        // arm64-v8a for a real phone, x86_64 for this machine's emulator --
        // the two ABIs every other experiment in RUST.md has actually run
        // on. `--abi` overrides either way.
        abis = vec!["arm64-v8a".to_string(), "x86_64".to_string()];
    }

    match apk::build(variant, &abis) {
        Ok(path) => {
            println!("==> Built {}", path.display());
            ExitCode::SUCCESS
        }
        Err(fail) => {
            eprintln!("xtask: {fail}");
            ExitCode::FAILURE
        }
    }
}