fig-sys 3.0.3

use std::env;
use std::fs;
use std::path::{Path, PathBuf};
use std::process::Command;

fn main() {
    // docs.rs builds documentation in a sandbox with no Zig toolchain and no
    // network access. `cargo doc` type-checks the crate but never links the
    // static library, so skip the native build entirely there — the bindings
    // still document cleanly. (Mirrors twig-sys's build.rs.)
    if env::var_os("DOCS_RS").is_some() {
        return;
    }

    println!("cargo:rerun-if-env-changed=FIG_SYS_FORCE_SOURCE");

    let cargo_target = env::var("TARGET").expect("Cargo should set TARGET");
    let cargo_host = env::var("HOST").expect("Cargo should set HOST");

    // Preferred path: link the prebuilt `libfig.a` shipped by the
    // `fig-sys-<target>` payload crate for this target — no Zig toolchain
    // required. Only usable when the active language features match the set the
    // prebuilt was compiled with (fig's `default`); any other combination
    // (extra or missing languages) needs a source build. Cargo reruns this
    // script when the feature set changes. Set FIG_SYS_FORCE_SOURCE=1 to always
    // build from source.
    if env::var_os("FIG_SYS_FORCE_SOURCE").is_none() && features_match_prebuilt() {
        if let Some(libdir) = prebuilt_libdir(&cargo_target) {
            println!("cargo:rustc-link-search=native={}", libdir.display());
            println!("cargo:rustc-link-lib=static=fig");
            println!("cargo:rerun-if-changed={}", libdir.display());
            return;
        }
    }

    build_from_source(&cargo_target, &cargo_host);
}

/// Whether the active cargo feature set matches the prebuilt `libfig.a`, which
/// is compiled with fig's **default** language set: `json`, `yaml`, `toml`,
/// `fig` on; `zon`, `xml` off. Any other combination — an extra language or a
/// disabled default — requires compiling the core from source so the linked
/// archive matches. (serde/derive/indexmap are Rust-only and don't affect this;
/// they aren't fig-sys features.)
fn features_match_prebuilt() -> bool {
    let on = |name: &str| env::var_os(format!("CARGO_FEATURE_{name}")).is_some();
    on("JSON") && on("YAML") && on("TOML") && on("FIG") && !on("ZON") && !on("XML")
}

/// Directory holding the prebuilt `libfig.a`/`fig.lib` for `target`, if a
/// payload crate is providing one. The active `fig-sys-<target>` payload crate
/// publishes its `lib/` directory as `DEP_FIG_PREBUILT_<KEY>_LIBDIR` (via its
/// `links` key); we resolve `<KEY>` from the target triple.
fn prebuilt_libdir(target: &str) -> Option<PathBuf> {
    let key = payload_env_key(target)?;
    let dir = PathBuf::from(env::var_os(format!("DEP_FIG_PREBUILT_{key}_LIBDIR"))?);
    let has_archive = ["libfig.a", "fig.lib"]
        .iter()
        .any(|name| dir.join(name).is_file());
    has_archive.then_some(dir)
}

/// Map a Rust target triple to its payload crate's env-var key, or `None` for
/// targets with no prebuilt library (which use the source build). Mirror of
/// `../prebuilt-targets.tsv` and the cfg-gated deps in `Cargo.toml`.
fn payload_env_key(target: &str) -> Option<&'static str> {
    Some(match target {
        "aarch64-apple-darwin" => "MACOS_ARM64",
        "x86_64-unknown-linux-gnu" => "LINUX_X64_GNU",
        "aarch64-unknown-linux-gnu" => "LINUX_ARM64_GNU",
        "x86_64-pc-windows-msvc" => "WINDOWS_X64_MSVC",
        "wasm32-unknown-unknown" => "WASM32",
        _ => return None,
    })
}

/// Compile `libfig.a` from the vendored/repo Zig source with the `zig`
/// toolchain, honoring the per-language cargo features. The fallback for
/// targets without a prebuilt payload, non-default feature sets, or
/// `FIG_SYS_FORCE_SOURCE`.
fn build_from_source(cargo_target: &str, cargo_host: &str) {
    let manifest_dir = PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").unwrap());
    let source_root = zig_source_root(&manifest_dir);
    let out_dir = PathBuf::from(env::var_os("OUT_DIR").unwrap());
    let prefix = out_dir.join("zig-prefix");

    let mut command = Command::new("zig");
    command
        .arg("build")
        .arg("install-c-lib")
        .arg("-Doptimize=ReleaseFast")
        .arg("-Dstrip=true")
        // Pin the CPU to the portable baseline. Without this, `zig build` for a
        // host target (no `-Dtarget`) compiles for the *build machine's* native
        // CPU, baking in whatever vector ISA it happens to have (AVX2/AVX-512:
        // `ymm`/`zmm`/`kmov`). The resulting `libfig.a` gets cached (e.g. by
        // Swatinem/rust-cache) and later restored onto a different, older CPU —
        // GitHub's x86_64 Linux runner fleet is heterogeneous — where the first
        // wide-vector instruction faults with SIGILL. Baseline codegen runs
        // everywhere; the parser is not vector-bound, so the cost is negligible.
        .arg("-Dcpu=baseline");

    if let Some(zig_target) = zig_target_for_cargo_target(cargo_target, cargo_host) {
        command.arg(format!("-Dtarget={zig_target}"));
    }

    // Mirror the per-language cargo features onto `build.zig`'s `-D<lang>` gates.
    // Cargo sets `CARGO_FEATURE_<NAME>` for every enabled feature; when one is
    // absent we pass `-D<lang>=false` so that format's parser/printer is compiled
    // out of `libfig.a`. `json` gates the shared JSON/JSONC/JSON5 core (on by
    // default like the rest). Cargo reruns this script automatically when the
    // active feature set changes.
    for (feature, flag) in [
        ("CARGO_FEATURE_JSON", "-Djson=false"),
        ("CARGO_FEATURE_YAML", "-Dyaml=false"),
        ("CARGO_FEATURE_TOML", "-Dtoml=false"),
        ("CARGO_FEATURE_ZON", "-Dzon=false"),
        ("CARGO_FEATURE_XML", "-Dxml=false"),
        ("CARGO_FEATURE_FIG", "-Dfig=false"),
    ] {
        if env::var_os(feature).is_none() {
            command.arg(flag);
        }
    }

    let status = command
        .arg("--prefix")
        .arg(&prefix)
        .current_dir(&source_root)
        .status()
        .unwrap_or_else(|e| {
            panic!(
                "fig-sys: this build needs to compile the fig core from source \
                 (target `{cargo_target}` has no prebuilt library, a non-default \
                 language feature set is active, or FIG_SYS_FORCE_SOURCE is set), \
                 but running `zig` failed: {e}.\n\
                 Default-feature builds for these targets need no Zig: \
                 aarch64-apple-darwin, x86_64-unknown-linux-gnu, \
                 aarch64-unknown-linux-gnu, x86_64-pc-windows-msvc, \
                 wasm32-unknown-unknown.\n\
                 Otherwise install Zig 0.16+ (https://ziglang.org/download/)."
            )
        });

    if !status.success() {
        panic!("`zig build` failed with status {status}");
    }

    // Apple's `ld` rejects Zig's static archive ("not 8-byte aligned"); repack
    // it with the system tools so it links. Applies to every Apple target
    // (macOS and iOS device/simulator), all of which link with ld64.
    if cargo_target.contains("apple") {
        repack_archive_for_apple_ld(&prefix.join("lib").join("libfig.a"));
    }

    println!(
        "cargo:rustc-link-search=native={}",
        prefix.join("lib").display()
    );
    println!("cargo:rustc-link-lib=static=fig");

    println!("cargo:rerun-if-env-changed=FIG_ZIG_ROOT");
    println!(
        "cargo:rerun-if-changed={}",
        source_root.join("build.zig").display()
    );
    println!(
        "cargo:rerun-if-changed={}",
        source_root.join("src").display()
    );
    println!(
        "cargo:rerun-if-changed={}",
        source_root.join("bindings/c/include/fig.h").display()
    );
}

/// Locate fig's Zig source tree — the working directory `zig build install-c-lib`
/// runs in. Three strategies, in priority order:
///
///   1. `FIG_ZIG_ROOT` — an explicit override for unusual layouts.
///   2. An ancestor directory that *is* the source tree — the in-repo case
///      (`bindings/rust/fig` lives under the repo root). Preferred over the
///      vendored copy so a working-tree build always uses live source, never a
///      stale vendor.
///   3. A `zig/` directory vendored next to this crate — the published case,
///      where there is no repo above us. Populated by `zig build vendor-rust` before
///      packaging and force-included via `Cargo.toml`'s `include`.
fn zig_source_root(manifest_dir: &Path) -> PathBuf {
    if let Some(dir) = env::var_os("FIG_ZIG_ROOT") {
        let dir = PathBuf::from(dir);
        assert!(
            is_fig_zig_root(&dir),
            "FIG_ZIG_ROOT={} is not a fig Zig source tree (no build.zig + src/c_api.zig)",
            dir.display()
        );
        return dir;
    }

    for ancestor in manifest_dir.ancestors() {
        if is_fig_zig_root(ancestor) {
            return ancestor.to_path_buf();
        }
    }

    let vendored = manifest_dir.join("zig");
    if is_fig_zig_root(&vendored) {
        return vendored;
    }

    panic!(
        "could not locate fig's Zig source. In a checkout it is found by walking up \
         from {}; in a published crate it is vendored at ./zig — run `zig build vendor-rust` \
         to populate it, or set FIG_ZIG_ROOT to a fig source tree.",
        manifest_dir.display()
    );
}

/// Whether `dir` is the root of fig's Zig source: enough of a fingerprint that we
/// won't mistake an unrelated `build.zig` for it.
fn is_fig_zig_root(dir: &Path) -> bool {
    dir.join("build.zig").is_file()
        && dir.join("build.zig.zon").is_file()
        && dir.join("src/c_api.zig").is_file()
}

/// Repackage a Zig-produced static archive so Apple's `ld` accepts it.
///
/// Zig's archiver writes members with a zero file mode and without 8-byte
/// alignment. LLD tolerates this, but ld64 errors with "not 8-byte aligned".
/// Extract the members, restore read permissions (so `libtool` can open them),
/// and rebuild the archive with `libtool`, whose output ld64 accepts.
fn repack_archive_for_apple_ld(lib_path: &Path) {
    let work = lib_path
        .parent()
        .expect("library path has a parent")
        .join("repack");
    let _ = fs::remove_dir_all(&work);
    fs::create_dir_all(&work).expect("create repack work dir");

    run(Command::new("ar").arg("x").arg(lib_path).current_dir(&work));

    // Collect the extracted object files, fixing their permissions.
    let mut objects = Vec::new();
    for entry in fs::read_dir(&work).expect("read repack work dir") {
        let path = entry.expect("dir entry").path();
        if path.extension().is_some_and(|ext| ext == "o") {
            run(Command::new("chmod").arg("u+rw").arg(&path));
            objects.push(path);
        }
    }
    assert!(
        !objects.is_empty(),
        "no object files extracted from {}",
        lib_path.display()
    );

    let mut libtool = Command::new("libtool");
    libtool
        .arg("-static")
        .arg("-o")
        .arg(lib_path)
        .args(&objects);
    run(&mut libtool);

    let _ = fs::remove_dir_all(&work);
}

fn run(command: &mut Command) {
    let status = command
        .status()
        .unwrap_or_else(|e| panic!("failed to run {command:?}: {e}"));
    if !status.success() {
        panic!("{command:?} failed with status {status}");
    }
}

fn zig_target_for_cargo_target(target: &str, host: &str) -> Option<&'static str> {
    // Windows MSVC must be handled before the `target == host` shortcut: Zig's
    // native default Windows ABI is GNU-style and emits `__chkstk_ms`, a
    // compiler-rt stack-probe symbol that Zig does not bundle into a static
    // lib, so the MSVC linker can't resolve it. Forcing the msvc ABI makes Zig
    // emit `__chkstk` (provided by the MSVC runtime) and keeps the static lib
    // ABI-compatible with the windows-msvc Rust binary it links into.
    match target {
        "x86_64-pc-windows-msvc" => return Some("x86_64-windows-msvc"),
        "aarch64-pc-windows-msvc" => return Some("aarch64-windows-msvc"),
        _ => {}
    }

    if target == host {
        return None;
    }

    match target {
        "aarch64-apple-darwin" => Some("aarch64-macos"),
        "x86_64-apple-darwin" => Some("x86_64-macos"),
        "aarch64-apple-ios" => Some("aarch64-ios"),
        "aarch64-apple-ios-sim" => Some("aarch64-ios-simulator"),
        "x86_64-apple-ios" => Some("x86_64-ios-simulator"),
        "aarch64-pc-windows-gnu" => Some("aarch64-windows-gnu"),
        "x86_64-pc-windows-gnu" => Some("x86_64-windows-gnu"),
        "i686-pc-windows-gnu" => Some("x86-windows-gnu"),
        "aarch64-unknown-linux-gnu" => Some("aarch64-linux-gnu"),
        "aarch64-unknown-linux-musl" => Some("aarch64-linux-musl"),
        "arm-unknown-linux-gnueabi" => Some("arm-linux-gnueabi"),
        "arm-unknown-linux-gnueabihf" => Some("arm-linux-gnueabihf"),
        "arm-unknown-linux-musleabi" => Some("arm-linux-musleabi"),
        "arm-unknown-linux-musleabihf" => Some("arm-linux-musleabihf"),
        "i686-unknown-linux-gnu" => Some("x86-linux-gnu"),
        "i686-unknown-linux-musl" => Some("x86-linux-musl"),
        "powerpc64le-unknown-linux-gnu" => Some("powerpc64le-linux-gnu"),
        "powerpc64le-unknown-linux-musl" => Some("powerpc64le-linux-musl"),
        "riscv64gc-unknown-linux-gnu" => Some("riscv64-linux-gnu"),
        "riscv64gc-unknown-linux-musl" => Some("riscv64-linux-musl"),
        "wasm32-unknown-unknown" => Some("wasm32-freestanding"),
        // Rust's WASI targets are `wasm32-wasip1` (née `wasm32-wasi`) and
        // `wasm32-wasip2`; Zig has no separate preview1/preview2 tag, just
        // `wasi` (preview1). `wasm32-wasip2` maps to the same Zig target: fig's
        // C surface does no I/O (no filesystem, no host calls) — it only
        // touches its own linear memory — so a preview1-ABI static lib links
        // and runs correctly under Rust's wasip2 sysroot, which supplies the
        // actual environment/component surface itself and never needs
        // anything from this library's own (nonexistent) WASI imports.
        // Verified by linking+running `fig/examples/wasm_smoke.rs` for both
        // targets under wasmtime; revisit if fig ever grows real I/O.
        "wasm32-wasip1" => Some("wasm32-wasi"),
        "wasm32-wasip2" => Some("wasm32-wasi"),
        "x86_64-unknown-linux-gnu" => Some("x86_64-linux-gnu"),
        "x86_64-unknown-linux-musl" => Some("x86_64-linux-musl"),
        _ => panic!(
            "unsupported Rust target `{target}` for fig's bundled Zig static library; \
             add a Cargo-to-Zig target mapping in bindings/rust/build.rs"
        ),
    }
}