const std = @import("std");

// Clean build configuration for optimized CLI (Zig 0.15 std.Build API)
pub fn build(b: *std.Build) void {
    // Standard target options
    const target = b.standardTargetOptions(.{});

    // Optimized release mode for size
    const optimize = b.standardOptimizeOption(.{ .preferred_optimize_mode = .ReleaseSmall });

    // CLI executable
    const exe = b.addExecutable(.{
        .name = "ml",
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/main.zig"),
            .target = target,
            .optimize = optimize,
        }),
    });

    // Install the executable to zig-out/bin
    b.installArtifact(exe);

    // Default build: install optimized CLI (used by `zig build`)
    const prod_step = b.step("prod", "Build production CLI binary");
    prod_step.dependOn(&exe.step);

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

    // Standard Zig test discovery - find all test files automatically
    const test_step = b.step("test", "Run unit tests");

    // Test main executable
    const main_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/main.zig"),
            .target = target,
            .optimize = .Debug,
        }),
    });
    const run_main_tests = b.addRunArtifact(main_tests);
    test_step.dependOn(&run_main_tests.step);

    // Find all test files in tests/ directory automatically
    var test_dir = std.fs.cwd().openDir("tests", .{}) catch |err| {
        std.log.warn("Failed to open tests directory: {}", .{err});
        return;
    };
    defer test_dir.close();

    // Create src module that tests can import from
    const src_module = b.createModule(.{
        .root_source_file = b.path("src.zig"),
        .target = target,
        .optimize = .Debug,
    });

    var iter = test_dir.iterate();
    while (iter.next() catch |err| {
        std.log.warn("Error iterating test files: {}", .{err});
        return;
    }) |entry| {
        if (entry.kind == .file and std.mem.endsWith(u8, entry.name, "_test.zig")) {
            const test_path = b.pathJoin(&.{ "tests", entry.name });

            const test_module = b.createModule(.{
                .root_source_file = b.path(test_path),
                .target = target,
                .optimize = .Debug,
            });

            // Make src module available to tests as "src"
            test_module.addImport("src", src_module);

            const test_exe = b.addTest(.{
                .root_module = test_module,
            });

            const run_test = b.addRunArtifact(test_exe);
            test_step.dependOn(&run_test.step);
        }
    }
}