const std = @import("std");

const CommonArgs = struct {
    target: std.Build.ResolvedTarget,
    optimize: std.builtin.OptimizeMode,
    ona_module: *std.Build.Module,
};

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

    const coral_module = b.addModule("coral", .{
        .root_source_file = b.path("src/coral/coral.zig"),
        .target = target,
        .optimize = optimize,
    });

    const ext_module = b.createModule(.{
        .root_source_file = b.path("src/ext/ext.zig"),
        .target = target,
        .optimize = optimize,
        .link_libc = true,
    });

    ext_module.linkSystemLibrary("SDL3", .{
        .needed = true,
        .preferred_link_mode = .dynamic,
    });

    const ona_module = b.addModule("ona", .{
        .root_source_file = b.path("src/ona/ona.zig"),
        .target = target,
        .optimize = optimize,
        .link_libc = true,

        .imports = &.{
            .{
                .name = "ext",
                .module = ext_module,
            },
            .{
                .name = "coral",
                .module = coral_module,
            },
        },
    });

    scan_demos(b, .{
        .target = target,
        .optimize = optimize,
        .ona_module = ona_module,
    });

    const test_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/tests.zig"),
            .target = target,
            .optimize = optimize,

            .imports = &.{
                .{
                    .name = "coral",
                    .module = coral_module,
                },
            },
        }),
    });

    const test_step = b.step("test", "Run unit tests");

    test_step.dependOn(&b.addRunArtifact(test_tests).step);
    test_step.dependOn(&b.addInstallArtifact(test_tests, .{}).step);
}

fn scan_demos(b: *std.Build, common: CommonArgs) void {
    const build_demos_step = b.step("demos", "Build demos");

    b.default_step.dependOn(build_demos_step);

    const cwd = std.fs.cwd();

    var demos_dir = cwd.openDir("src/demos/", .{ .iterate = true }) catch {
        return build_demos_step.dependOn(&b.addFail("failed to open demo files directory").step);
    };

    defer {
        demos_dir.close();
    }

    var demos_iterator = demos_dir.iterate();

    while (demos_iterator.next() catch {
        return build_demos_step.dependOn(&b.addFail("failed to iterate over next entry in demos directory").step);
    }) |entry| {
        if (entry.kind != .file) {
            continue;
        }

        if (!std.mem.eql(u8, std.fs.path.extension(entry.name), ".zig")) {
            continue;
        }

        const demo_executable = b.addExecutable(.{
            .name = std.fmt.allocPrint(b.allocator, "{s}_demo", .{std.fs.path.stem(entry.name)}) catch {
                return build_demos_step.dependOn(&b.addFail("failed to allocate demo name buffer").step);
            },

            .root_module = b.createModule(.{
                .root_source_file = b.path(b.pathJoin(&.{ "src/demos/", entry.name })),
                .target = common.target,
                .optimize = common.optimize,

                .imports = &.{
                    .{
                        .name = "ona",
                        .module = common.ona_module,
                    },
                },
            }),
        });

        demo_executable.linkSystemLibrary2("SDL3", .{
            .needed = true,
            .preferred_link_mode = .dynamic,
        });

        const demo_installation = b.addInstallArtifact(demo_executable, .{});

        build_demos_step.dependOn(&demo_installation.step);
    }
}