const std = @import("std");
const builtin = @import("builtin");

// Although this function looks imperative, note that its job is to
// declaratively construct a build graph that will be executed by an external
// runner.
pub fn build(b: *std.Build) void {
    // Standard target options allows the person running `zig build` to choose
    // what target to build for. Here we do not override the defaults, which
    // means any target is allowed, and the default is native. Other options
    // for restricting supported target set are available.
    const target = b.standardTargetOptions(.{});

    // Standard optimization options allow the person running `zig build` to select
    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
    // set a preferred release mode, allowing the user to decide how to optimize.
    const optimize = b.standardOptimizeOption(.{});

    const lib = b.addSharedLibrary(.{
        .name = "gmsynth",
        // In this case the main source file is merely a path, however, in more
        // complicated build scripts, this could be a generated file.
        .root_source_file = .{ .path = "src/main.zig" },
        .target = target,
        .optimize = optimize,
    });

    // Zig deps!
    const glfw = b.dependency("glfw", .{
        .target = target,
        .optimize = optimize,
    }).module("glfw");
    lib.addModule("glfw", glfw);

    // const objc = b.dependency("objc", .{
    //     .target = target,
    //     .optimize = optimize,
    // }).module("objc");
    // lib.addModule("objc", objc);

    // We use translate-c to "build" the clap/clap.h header, so
    // that we can add manual edits.
    // lib.addIncludePath("deps/clap/include");
    lib.addIncludePath("deps/wgpu/ffi");
    lib.addLibraryPath("deps/wgpu/target/release/");
    lib.linkSystemLibraryNeeded("wgpu_native");
    // The sacrifices I make for windowing code...
    if (builtin.os.tag == .linux) {
        // We only link libC C code (wgpu-native is a Rust library)
        // when compiling for Linux I think
        lib.linkLibC();
        const sessionType = std.os.getenv("XDG_SESSION_TYPE");
        if (sessionType) |stype| {
            if (std.mem.eql(u8, stype, "x11")) {
                lib.linkSystemLibrary("X11");
            } else if (std.mem.eql(u8, stype, "wayland")) {
                lib.linkSystemLibrary("wayland-client");
            } else {
                @panic("Unsupported XDG_SESSION_TYPE");
            }
        } else {
            // How are you even reading this?
            @panic("Missing XDG_SESSION_TYPE");
        }
    }

    // This declares intent for the library to be installed into the standard
    // location when the user invokes the "install" step (the default step when
    // running `zig build`).
    b.installArtifact(lib);

    // Creates a step for unit testing. This only builds the test executable
    // but does not run it.
    const main_tests = b.addTest(.{
        .root_source_file = .{ .path = "src/main.zig" },
        .target = target,
        .optimize = optimize,
    });

    const run_main_tests = b.addRunArtifact(main_tests);

    // This creates a build step. It will be visible in the `zig build --help` menu,
    // and can be selected like this: `zig build test`
    // This will evaluate the `test` step rather than the default, which is "install".
    const test_step = b.step("test", "Run library tests");
    test_step.dependOn(&run_main_tests.step);
}