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

pub fn build(b: *std.Build) !void {
    // Default to aarch64-linux for Lambda Graviton deployment
    const target = b.standardTargetOptions(.{
        .default_target = .{
            .cpu_arch = .aarch64,
            .os_tag = .linux,
        },
    });
    const optimize = b.standardOptimizeOption(.{});

    // Native target for build tools
    const native_target = b.resolveTargetQuery(.{});

    // Get lambda-zig dependency
    const lambda_zig_dep = b.dependency("lambda_zig", .{
        .target = target,
        .optimize = optimize,
    });

    // Get controlr dependency for rinnai module
    const controlr_dep = b.dependency("controlr", .{
        .target = target,
        .optimize = optimize,
    });

    // Create the main module
    const main_module = b.createModule(.{
        .root_source_file = b.path("src/main.zig"),
        .target = target,
        .optimize = optimize,
    });

    // Add lambda_runtime import
    main_module.addImport("lambda_runtime", lambda_zig_dep.module("lambda_runtime"));
    // Add rinnai import from controlr
    main_module.addImport("rinnai", controlr_dep.module("rinnai"));

    // Create executable
    const exe = b.addExecutable(.{
        .name = "house-control",
        .root_module = main_module,
    });

    b.installArtifact(exe);

    // Configure Lambda build steps and get deployment info
    // Function name defaults to exe.name ("house-control")
    const lambda = try lambda_zig.configureBuild(b, lambda_zig_dep, exe, .{});

    // Get AWS profile option (already declared by lambda-zig)
    const profile = b.user_input_options.get("profile");
    const profile_str: ?[]const u8 = if (profile) |p| switch (p.value) {
        .scalar => |s| s,
        else => null,
    } else null;

    // Get AWS region option (already declared by lambda-zig)
    const region = b.user_input_options.get("region");
    const region_str: ?[]const u8 = if (region) |r| switch (r.value) {
        .scalar => |s| s,
        else => null,
    } else null;

    // Build the gen-skill-json tool (runs on host)
    const gen_skill_json_module = b.createModule(.{
        .root_source_file = b.path("tools/gen-skill-json.zig"),
        .target = native_target,
        .optimize = .ReleaseSafe,
    });
    const gen_skill_json_exe = b.addExecutable(.{
        .name = "gen-skill-json",
        .root_module = gen_skill_json_module,
    });

    // Generate skill.json from template using Lambda ARN
    const gen_skill_cmd = b.addRunArtifact(gen_skill_json_exe);
    gen_skill_cmd.addFileArg(lambda.deploy_output);
    gen_skill_cmd.addFileArg(b.path("skill.template.json"));
    gen_skill_cmd.step.dependOn(lambda.deploy_step);

    // Capture generated skill.json
    const skill_json = gen_skill_cmd.captureStdOut();

    // Write skill.json to skill-package directory (updates source files, necessary for the ask deploy)
    const write_skill_json = b.addUpdateSourceFiles();
    write_skill_json.addCopyFileToSource(skill_json, "skill-package/skill.json");

    const gen_skill_step = b.step("gen_skill_json", "Generate skill.json from template (will deploy function)");
    gen_skill_step.dependOn(&write_skill_json.step);

    // ASK CLI deploy step for Alexa skill metadata
    const ask_deploy_cmd = b.addSystemCommand(&.{
        "bun", "x", "ask", "deploy", "--target", "skill-metadata",
    });
    // ASK deploy depends on skill.json being generated
    ask_deploy_cmd.step.dependOn(&write_skill_json.step);

    // Add Alexa skill-specific Lambda permission
    //
    // Alexa requires a skill-specific Lambda permission with the skill ID as an
    // event_source_token condition. This is more secure than a generic principal-based
    // permission (--allow-principal) and restricts invocation to only our specific skill.
    //
    // We use our own tool instead of lambda-zig's built-in --allow-principal because:
    // 1. The skill ID isn't known until after ASK deploy runs
    // 2. event_source_token is Alexa-specific (not supported by lambda-zig)
    //
    // Pipeline: Lambda deploy -> gen-skill-json -> ASK deploy -> add-alexa-permission
    const aws_dep = b.dependency("aws", .{
        .target = native_target,
        .optimize = .ReleaseSafe,
    });
    const add_alexa_perm_module = b.createModule(.{
        .root_source_file = b.path("tools/add-alexa-permission.zig"),
        .target = native_target,
        .optimize = .ReleaseSafe,
    });
    add_alexa_perm_module.addImport("aws", aws_dep.module("aws"));
    const add_alexa_perm_exe = b.addExecutable(.{
        .name = "add-alexa-permission",
        .root_module = add_alexa_perm_module,
    });
    const add_alexa_perm_cmd = b.addRunArtifact(add_alexa_perm_exe);
    add_alexa_perm_cmd.addFileArg(lambda.deploy_output);
    add_alexa_perm_cmd.addFileArg(b.path(".ask/ask-states.json"));
    if (profile_str) |p| {
        add_alexa_perm_cmd.addArgs(&.{ "--profile", p });
    }
    if (region_str) |r| {
        add_alexa_perm_cmd.addArgs(&.{ "--region", r });
    }
    // Must run after ASK deploy (which creates/updates skill ID) and Lambda deploy
    add_alexa_perm_cmd.step.dependOn(&ask_deploy_cmd.step);

    const ask_deploy_step = b.step("ask_deploy", "Deploy Alexa skill metadata via ASK CLI");
    ask_deploy_step.dependOn(&add_alexa_perm_cmd.step);

    // Full deploy step - deploys Lambda, generates skill.json, deploys Alexa skill, adds permission
    const full_deploy_step = b.step("deploy", "Deploy Lambda function and Alexa skill");
    full_deploy_step.dependOn(&add_alexa_perm_cmd.step);

    // Test step - use native target for tests (not cross-compiled Lambda target)
    const lambda_zig_dep_native = b.dependency("lambda_zig", .{
        .target = native_target,
        .optimize = optimize,
    });

    const controlr_dep_native = b.dependency("controlr", .{
        .target = native_target,
        .optimize = optimize,
    });

    const test_module = b.createModule(.{
        .root_source_file = b.path("src/main.zig"),
        .target = native_target,
        .optimize = optimize,
    });
    test_module.addImport("lambda_runtime", lambda_zig_dep_native.module("lambda_runtime"));
    test_module.addImport("rinnai", controlr_dep_native.module("rinnai"));

    const main_tests = b.addTest(.{
        .name = "test",
        .root_module = test_module,
    });

    const run_main_tests = b.addRunArtifact(main_tests);
    const test_step = b.step("test", "Run unit tests");
    test_step.dependOn(&run_main_tests.step);
    // Also verify tools compile
    test_step.dependOn(&gen_skill_json_exe.step);
    test_step.dependOn(&add_alexa_perm_exe.step);

    // Run step for local testing (uses native target)
    const run_module = b.createModule(.{
        .root_source_file = b.path("src/main.zig"),
        .target = native_target,
        .optimize = optimize,
    });
    run_module.addImport("lambda_runtime", lambda_zig_dep_native.module("lambda_runtime"));
    run_module.addImport("rinnai", controlr_dep_native.module("rinnai"));

    const run_exe = b.addExecutable(.{
        .name = exe.name,
        .root_module = run_module,
    });

    const run_cmd = b.addRunArtifact(run_exe);
    if (b.args) |args| {
        run_cmd.addArgs(args);
    }

    const run_step = b.step("run", "Run locally for testing");
    run_step.dependOn(&run_cmd.step);
}