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

pub fn build(b: *std.Build) void {
    const opts = bh.declareOptions(b);

    // am i good to always have enet as static?
    // const enet = if (true) b.addStaticLibrary(.{
    //     .name = "enet_c",
    //     .target = target,
    //     .optimize = optimize,
    // }) else b.addSharedLibrary(.{
    //     .name = "enet_c",
    //     .target = target,
    //     .optimize = optimize,
    // });

    const enet = b.addLibrary(.{
        .name = "enet_c",
        .linkage = .static,
        .root_module = b.createModule(.{
            .target = opts.target,
            .optimize = opts.optimize,
        }),
    });

    enet.linkLibC();

    enet.addCSourceFiles(.{
        .root = b.path("enet-1.3.18"),
        .files = &.{
            "callbacks.c",
            "compress.c",
            "host.c",
            "list.c",
            "packet.c",
            "peer.c",
            "protocol.c",
            "win32.c",
            "unix.c",
        },
        .flags = &.{"-DHAS_OFFSETOF=1"},
    });

    enet.addIncludePath(b.path("enet-1.3.18/include"));

    // Platform-specific configuration
    switch (opts.target.result.os.tag) {
        .windows => {
            enet.linkSystemLibrary("ws2_32");
            enet.linkSystemLibrary("winmm");
            // Use .def file to control exports and avoid CRT symbol conflicts
        },
        .linux, .macos => {
            // Unix platforms - no additional libraries needed
        },
        else => {},
    }

    b.installArtifact(enet);

    const mod = b.addModule("enet", .{
        .target = opts.target,
        .optimize = opts.optimize,
        .root_source_file = b.path("src/enet.zig"),
        .link_libc = true,
    });

    mod.linkLibrary(enet);
    mod.addIncludePath(b.path("enet-1.3.18/include/"));

    const test_step = b.step("test", "run unit tests for enet");
    const tests = b.addTest(.{
        .root_module = b.createModule(.{
            .link_libc = true,
            .target = opts.target,
            .optimize = opts.optimize,
            .root_source_file = b.path("src/tests.zig"),
        }),
    });

    tests.root_module.addImport("enet", mod);
    tests.root_module.addIncludePath(b.path("enet-1.3.18/include/"));
    const runArtifact = b.addRunArtifact(tests);
    test_step.dependOn(&runArtifact.step);

    // Test server executable
    const test_server = b.addExecutable(.{
        .name = "test-server",
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/test_server.zig"),
            .target = opts.target,
            .optimize = opts.optimize,
        }),
    });
    test_server.root_module.addImport("enet", mod);
    test_server.linkLibC();

    // Test client executable
    const test_client = b.addExecutable(.{
        .name = "test-client",
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/test_client.zig"),
            .target = opts.target,
            .optimize = opts.optimize,
        }),
    });
    test_client.root_module.addImport("enet", mod);
    test_client.linkLibC();

    // Install test programs
    const install_test_server = b.addInstallArtifact(test_server, .{});
    const install_test_client = b.addInstallArtifact(test_client, .{});

    // Steps to run test programs individually
    const run_test_server = b.addRunArtifact(test_server);
    const run_test_client = b.addRunArtifact(test_client);

    const run_server_step = b.step("run-test-server", "Run the ENet test server");
    run_server_step.dependOn(&run_test_server.step);

    const run_client_step = b.step("run-test-client", "Run the ENet test client");
    run_client_step.dependOn(&run_test_client.step);

    // Loopback test that runs both server and client
    const run_loopback_step = b.step("run-test-loopback", "Run ENet loopback test (server + client)");

    // Create a custom step for the loopback test
    const loopback_test = LoopbackTestStep.create(b, test_server, test_client);
    run_loopback_step.dependOn(&loopback_test.step);

    // Build step for test programs
    const build_tests_step = b.step("build-tests", "Build test server and client programs");
    build_tests_step.dependOn(&install_test_server.step);
    build_tests_step.dependOn(&install_test_client.step);
}

// Custom step to run server and client concurrently for loopback testing
const LoopbackTestStep = struct {
    step: std.Build.Step,
    builder: *std.Build,
    server_exe: *std.Build.Step.Compile,
    client_exe: *std.Build.Step.Compile,

    const Self = @This();

    pub fn create(builder: *std.Build, server_exe: *std.Build.Step.Compile, client_exe: *std.Build.Step.Compile) *Self {
        const self = builder.allocator.create(Self) catch @panic("OOM");
        self.* = Self{
            .step = std.Build.Step.init(.{
                .id = .custom,
                .name = "loopback-test",
                .owner = builder,
                .makeFn = make,
            }),
            .builder = builder,
            .server_exe = server_exe,
            .client_exe = client_exe,
        };

        self.step.dependOn(&server_exe.step);
        self.step.dependOn(&client_exe.step);

        return self;
    }

    fn make(step: *std.Build.Step, _: std.Build.Step.MakeOptions) !void {
        const self: *Self = @fieldParentPtr("step", step);
        const allocator = self.builder.allocator;

        std.debug.print("Running ENet loopback test...\n", .{});

        // Get the executable paths
        const server_path = self.server_exe.getEmittedBin().getPath(self.builder);
        const client_path = self.client_exe.getEmittedBin().getPath(self.builder);

        // Start the server process
        std.debug.print("Starting test server...\n", .{});
        var server_process = std.process.Child.init(&[_][]const u8{server_path}, allocator);
        server_process.stdout_behavior = .Pipe;
        server_process.stderr_behavior = .Pipe;

        try server_process.spawn();
        defer {
            _ = server_process.kill() catch {};
        }

        // Give server time to start
        std.Thread.sleep(1 * std.time.ns_per_s);

        // Start the client process
        std.debug.print("Starting test client...\n", .{});
        var client_process = std.process.Child.init(&[_][]const u8{client_path}, allocator);
        client_process.stdout_behavior = .Pipe;
        client_process.stderr_behavior = .Pipe;

        try client_process.spawn();

        // Wait for client to complete
        const client_result = try client_process.wait();

        // Give server a moment to process the quit message and shut down naturally
        std.Thread.sleep(2 * std.time.ns_per_s);

        // Check if server is still running and terminate if needed
        const server_result = server_process.wait() catch {
            std.debug.print("Server still running, terminating...\n", .{});
            _ = server_process.kill() catch {};
            return;
        };

        // Read and display output
        if (client_process.stdout) |stdout| {
            const client_output = try stdout.readToEndAlloc(allocator, 8192);
            defer allocator.free(client_output);
            std.debug.print("\n=== CLIENT OUTPUT ===\n{s}\n", .{client_output});
        }

        if (server_process.stdout) |stdout| {
            const output = try stdout.readToEndAlloc(allocator, 8192);
            // const server_output = try stdout.readToEndAlloc.read(allocator, 8192);
            defer allocator.free(output);
            std.debug.print("\n=== SERVER OUTPUT ===\n{s}\n", .{output});
        }

        std.debug.print("\n=== LOOPBACK TEST RESULTS ===\n", .{});
        std.debug.print("Client exit code: {}\n", .{client_result});
        std.debug.print("Server exit code: {}\n", .{server_result});

        if (client_result == .Exited and client_result.Exited == 0 and
            server_result == .Exited and server_result.Exited == 0)
        {
            std.debug.print("Loopback test PASSED!\n", .{});
        } else {
            std.debug.print("Loopback test FAILED!\n", .{});
            return error.TestFailed;
        }
    }
};