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

const HEAD_location = ".git/HEAD";
const commit_location = ".git/refs/heads/master";

const common_c_files = &[_][]const u8 {
    "src/utils/stringBuilder.c",
    "src/utils/arena.c",
    "src/wren_inter/wren_inter.c",
    "src/resources/resources.c",
    "src/resources/config.c",
    "src/ui_elements/UI.c",
    "src/ui_elements/TextEditor.c",
    "src/ui_elements/Button.c",
    "src/scenes/sceneManager.c",
    "src/scenes/mainMenu.c",
    "src/scenes/resultView.c",
    "src/scenes/puzzleScene.c",
    "src/scenes/distractionScene.c",
    "src/scenes/collectionScene.c",
    "src/puzzles/puzzle.c",
    "src/puzzles/parser.c",
    "src/puzzles/distractions.c",
};

pub fn build(b: *std.Build) void {
    const target = b.standardTargetOptions(.{});
    const optimize = b.standardOptimizeOption(.{});

    // ========== Building a game ==========

    var game_root = b.addModule("game-mod", .{
        .optimize = optimize,
        .target = target,
        .link_libc = true,
    });
    FillModule(b, game_root, optimize);

    // The entry point. This is put there separatly to separate from tests entry point
    game_root.addCSourceFile(.{ .file = b.path("src/main.c") });

    const exe = b.addExecutable(.{
        .name = "game",
        .root_module = game_root,
    });

    b.installArtifact(exe);

    // ========== Running a game ==========

    const run_step = b.step("run", "Run the app");
    const run_cmd = b.addRunArtifact(exe);
    run_step.dependOn(&run_cmd.step);
    if (b.args) |args| {
        run_cmd.addArgs(args);
    }

    // ========== Building and running tests ==========
    
    const test_runner_root = b.addModule("test-runner-mod", .{
        .optimize = optimize,
        .target = target,
        .link_libc = true,
    });
    FillModule(b, test_runner_root, optimize);

    // The only difference is the additional files
    test_runner_root.addCSourceFiles(.{
        .files = &[_][]const u8 {
            "src/tests/runner.c",
            "src/tests/arena_tests.c",
            "src/tests/difficulty_calc.c",
        }
    });

    const test_runner_exe = b.addExecutable(.{
        .name = "game_tests",
        .root_module = test_runner_root,
    });

    const test_run_step = b.step("test", "Run the test app");
    const test_run_cmd = b.addRunArtifact(test_runner_exe);
    test_run_step.dependOn(&test_run_cmd.step);
    if (b.args) |args| {
        test_run_cmd.addArgs(args);
    }

}

fn FillModule(b: *std.Build, mod: *std.Build.Module, opt: std.builtin.OptimizeMode) void {
    // Adding a build version
    const build_ver = GetVersionString(b, opt) catch "Build UNTRACKED";
    if (build_ver.len > 0)
        mod.addCMacro("BUILD_VERSION", build_ver);

    mod.addCSourceFiles(.{
        .files = common_c_files,
    });

    // Linking raylib
    if (builtin.target.os.tag == .windows) {
        // If you are building on windows you need to provide your own 
        // raylib. Put it in the raylib dir
        mod.addLibraryPath(b.path("raylib/lib/"));
        mod.addIncludePath(b.path("raylib/include/"));
    }

    mod.linkSystemLibrary("raylib", .{.needed = true});
    mod.addIncludePath(b.path("include/"));

    // Linking wren. They do not provide system-wide libraries so you have to 
    // provide them yourself
    mod.addIncludePath(b.path("wren/src/include/"));
    mod.addLibraryPath(b.path("wren/lib/"));
    mod.linkSystemLibrary("wren", .{ 
        .needed = true, 
        .preferred_link_mode = .static,
    });
}

// Returns a build version. Returns an empty string if build in release mode
fn GetVersionString(b: *std.Build, optimization: std.builtin.OptimizeMode) ![]u8 {
    if (optimization != .Debug) {
        return "";
    }

    const allocator = b.allocator;
    var threaded = std.Io.Threaded.init(allocator, .{});
    defer threaded.deinit();

    const headContents = try std.Io.Dir.cwd().readFileAlloc(threaded.io(), HEAD_location, allocator, .limited(std.math.maxInt(usize)));
    var headIter = std.mem.tokenizeAny(u8, headContents[0..headContents.len - 1], "/");
    var branchName: []const u8 = "";
    while (headIter.next()) |token| {
        branchName = token;
    }
    const commitContents = try std.Io.Dir.cwd().readFileAlloc(threaded.io(), commit_location, allocator, .limited(std.math.maxInt(usize)));
    return try std.fmt.allocPrint(allocator, "\"Build {s}:{s}\"", .{
        branchName,
        commitContents[0..@min(commitContents.len-1, 10)]
    });
}