const std = @import("std");

pub const Backend = enum {
    no_backend,
    glfw_wgpu,
    win32_dx12,
};

pub const Options = struct {
    backend: Backend,
    shared: bool = false,
    /// use bundled imgui source
    with_imgui: bool = true,
    /// use bundled implot source
    with_implot: bool = true,
};

pub const Package = struct {
    options: Options,
    zgui: *std.Build.Module,
    zgui_options: *std.Build.Module,
    zgui_c_cpp: *std.Build.CompileStep,

    pub fn link(pkg: Package, exe: *std.Build.CompileStep) void {
        exe.linkLibrary(pkg.zgui_c_cpp);
        exe.addModule("zgui", pkg.zgui);
    }
};

pub fn package(
    b: *std.Build,
    target: std.zig.CrossTarget,
    optimize: std.builtin.Mode,
    args: struct {
        options: Options,
    },
) Package {
    const step = b.addOptions();
    step.addOption(Backend, "backend", args.options.backend);
    step.addOption(bool, "shared", args.options.shared);

    const zgui_options = step.createModule();

    const zgui = b.createModule(.{
        .source_file = .{ .path = thisDir() ++ "/src/gui.zig" },
        .dependencies = &.{
            .{ .name = "zgui_options", .module = zgui_options },
        },
    });

    const zgui_c_cpp = if (args.options.shared) blk: {
        const lib = b.addSharedLibrary(.{
            .name = "zgui",
            .target = target,
            .optimize = optimize,
        });

        b.installArtifact(lib);
        if (target.isWindows()) {
            lib.defineCMacro("IMGUI_API", "__declspec(dllexport)");
            lib.defineCMacro("IMPLOT_API", "__declspec(dllexport)");
            lib.defineCMacro("ZGUI_API", "__declspec(dllexport)");
        }

        break :blk lib;
    } else b.addStaticLibrary(.{
        .name = "zgui",
        .target = target,
        .optimize = optimize,
    });

    zgui_c_cpp.addIncludePath(.{ .path = thisDir() ++ "/libs" });
    zgui_c_cpp.addIncludePath(.{ .path = thisDir() ++ "/libs/imgui" });

    zgui_c_cpp.linkLibC();
    zgui_c_cpp.linkLibCpp();

    const cflags = &.{"-fno-sanitize=undefined"};

    zgui_c_cpp.addCSourceFile(.{
        .file = .{ .path = thisDir() ++ "/src/zgui.cpp" },
        .flags = cflags,
    });

    if (args.options.with_imgui) {
        zgui_c_cpp.addCSourceFiles(&.{
            thisDir() ++ "/libs/imgui/imgui.cpp",
            thisDir() ++ "/libs/imgui/imgui_widgets.cpp",
            thisDir() ++ "/libs/imgui/imgui_tables.cpp",
            thisDir() ++ "/libs/imgui/imgui_draw.cpp",
            thisDir() ++ "/libs/imgui/imgui_demo.cpp",
        }, cflags);
    }

    if (args.options.with_implot) {
        zgui_c_cpp.addCSourceFiles(&.{
            thisDir() ++ "/libs/imgui/implot_demo.cpp",
            thisDir() ++ "/libs/imgui/implot.cpp",
            thisDir() ++ "/libs/imgui/implot_items.cpp",
        }, cflags);
    }

    switch (args.options.backend) {
        .glfw_wgpu => {
            zgui_c_cpp.addIncludePath(.{ .path = thisDir() ++ "/../zglfw/libs/glfw/include" });
            zgui_c_cpp.addIncludePath(.{ .path = thisDir() ++ "/../zgpu/libs/dawn/include" });
            zgui_c_cpp.addCSourceFiles(&.{
                thisDir() ++ "/libs/imgui/backends/imgui_impl_glfw.cpp",
                thisDir() ++ "/libs/imgui/backends/imgui_impl_wgpu.cpp",
            }, cflags);
        },
        .win32_dx12 => {
            zgui_c_cpp.addCSourceFiles(&.{
                thisDir() ++ "/libs/imgui/backends/imgui_impl_win32.cpp",
                thisDir() ++ "/libs/imgui/backends/imgui_impl_dx12.cpp",
            }, cflags);
            zgui_c_cpp.linkSystemLibraryName("d3dcompiler_47");
            zgui_c_cpp.linkSystemLibraryName("dwmapi");
        },
        .no_backend => {},
    }

    return .{
        .options = args.options,
        .zgui = zgui,
        .zgui_options = zgui_options,
        .zgui_c_cpp = zgui_c_cpp,
    };
}

pub fn build(_: *std.Build) void {}

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