const std = @import("std");
const gpu_dawn = @import("libs/mach-gpu-dawn/build.zig");
const glfw = @import("libs/mach-glfw/build.zig");

pub fn build(b: *std.build.Builder) void {
    const mode = b.standardReleaseOptions();
    const target = b.standardTargetOptions(.{});

    const gpu_dawn_options = gpu_dawn.Options{
        .from_source = b.option(bool, "dawn-from-source", "Build Dawn from source") orelse false,
    };

    const test_step = b.step("test", "Run library tests");
    test_step.dependOn(&testStep(b, mode, .{ .gpu_dawn_options = gpu_dawn_options }).step);

    const example = b.addExecutable("gpu-hello-triangle", "examples/main.zig");
    example.setTarget(target);
    example.setBuildMode(mode);
    example.install();
    example.linkLibC();
    example.addPackagePath("gpu", "src/main.zig");
    example.addPackagePath("glfw", "libs/mach-glfw/src/main.zig");
    link(b, example, .{ .gpu_dawn_options = gpu_dawn_options });

    const example_run_cmd = example.run();
    example_run_cmd.step.dependOn(b.getInstallStep());
    const example_run_step = b.step("run-example", "Run the example");
    example_run_step.dependOn(&example_run_cmd.step);
}

pub fn testStep(b: *std.build.Builder, mode: std.builtin.Mode, options: Options) *std.build.LibExeObjStep {
    const main_tests = b.addTest(thisDir() ++ "/src/main.zig");
    main_tests.setBuildMode(mode);
    link(b, main_tests, options);
    return main_tests;
}

pub const Options = struct {
    glfw_options: glfw.Options = .{},
    gpu_dawn_options: gpu_dawn.Options = .{},
};

pub const pkg = std.build.Pkg{
    .name = "gpu",
    .source = .{ .path = thisDir() ++ "/src/main.zig" },
    .dependencies = &.{glfw.pkg},
};

pub fn link(b: *std.build.Builder, step: *std.build.LibExeObjStep, options: Options) void {
    if (step.target.toTarget().cpu.arch != .wasm32) {
        glfw.link(b, step, options.glfw_options);
        gpu_dawn.link(b, step, options.gpu_dawn_options);
    }
}

fn thisDir() []const u8 {
    return std.fs.path.dirname(@src().file) orelse ".";
}