//! Rust application for ESP32-S3
//! 
//! This module provides the main Rust application logic
//! that interacts with the USB HID interface implemented in C/TinyUSB.

#![no_std]
#![no_main]

use esp_backtrace as _;

#[panic_handler]
fn panic(_info: &core::panic::PanicInfo) -> ! {
    loop {
        core::hint::spin_loop();
    }
}

// HID 键码常量
const HID_KEY_A: u8 = 0x04;
const REPORT_ID_KEYBOARD: u8 = 1;
const REPORT_ID_MOUSE: u8 = 2;

// FFI 函数声明
extern "C" {
    fn rust_is_usb_mounted() -> bool;
    fn rust_send_keyboard_report(report_id: u8, modifier: u8, keycode: *const u8);
    fn rust_send_mouse_report(report_id: u8, buttons: u8, x: i8, y: i8, wheel: i8, pan: i8);
    fn rust_vTaskDelay(xTicksToDelay: u32);
    fn rust_esp_log_i(tag: *const u8, format: *const u8);
}

/// 日志函数
fn log_info(message: &'static str) {
    // 转换 Rust 静态字符串为 C 字符串
    let tag = b"RustApp\0";
    
    // 直接使用静态字符串的指针，确保它在整个程序生命周期内有效
    // 注意：Rust 的字符串字面量已经以 null 结尾
    let msg_ptr = message.as_ptr();
    
    unsafe {
        rust_esp_log_i(tag.as_ptr(), msg_ptr);
    }
}

#[no_mangle]
extern "C" fn rust_app_main() {
    // 初始化代码
    log_info("Rust app started");
    
    // 等待 USB 挂载成功
    wait_usb_mounted();
    
    let mut tick_count = 0;
    loop {
        // 每 5 秒 (500 ticks) 按下一个随机键
        if tick_count % 500 == 0 {
            log_info("Sending random key...");
            send_random_key();
        }
        
        // 每 6 秒 (600 ticks) 随机移动一下鼠标
        if tick_count % 600 == 0 {
            log_info("Sending random mouse move...");
            send_random_mouse_move();
        }
        
        // 等待 10ms (1 tick)
        unsafe {
            rust_vTaskDelay(1);
        }
        tick_count += 1;
    }
}

/// 等待 USB 挂载成功
fn wait_usb_mounted() {
    // 等待 USB 设备挂载，最多等待 3 秒
    const USB_MOUNT_TIMEOUT_TICKS: u32 = 300; // 300 ticks = 3 seconds
    let mut elapsed_ticks = 0;
    
    log_info("Waiting for USB to mount...");
    
    loop {
        let mounted = unsafe {
            rust_is_usb_mounted()
        };
        
        if mounted {
            log_info("USB mounted successfully!");
            break;
        }
        
        // 检查是否超时
        if elapsed_ticks >= USB_MOUNT_TIMEOUT_TICKS {
            log_info("USB mount timeout!");
            // 使用 panic! 而不是 unreachable_unchecked
            panic!("USB init failed");
        }
        
        // 等待 10ms (1 tick)
        unsafe {
            rust_vTaskDelay(1);
        }
        elapsed_ticks += 1;
    }
}

#[export_name = "rust_usb_callback"]
pub unsafe extern "C" fn usb_callback(_event: u32) {
}

/// 发送 A-Z 随机键的按键事件
fn send_random_key() {
    // 检查 USB 是否仍然挂载
    let mounted = unsafe {
        rust_is_usb_mounted()
    };
    
    if !mounted {
        log_info("USB not mounted, skipping key press");
        return;
    }
    
    // 生成随机的 A-Z 键码
    let random_value = get_random_u32() % 26;
    let random_key = HID_KEY_A + (random_value as u8);
    
    // 发送随机键按下事件
    let keycode = [random_key, 0, 0, 0, 0, 0];
    log_info("Sending key press event");
    unsafe {
        rust_send_keyboard_report(REPORT_ID_KEYBOARD, 0, keycode.as_ptr());
    }

    // 等待 50ms (50ms / 10ms per tick = 5 ticks)
    log_info("Waiting for 50ms...");
    unsafe {
        rust_vTaskDelay(5);
    }

    // 再次检查 USB 是否仍然挂载
    let mounted = unsafe {
        rust_is_usb_mounted()
    };
    
    if !mounted {
        log_info("USB not mounted, skipping key release");
        return;
    }

    // 发送随机键释放事件
    let keycode = [0, 0, 0, 0, 0, 0];
    log_info("Sending key release event");
    unsafe {
        rust_send_keyboard_report(REPORT_ID_KEYBOARD, 0, keycode.as_ptr());
    }
}

/// 发送随机鼠标移动事件
fn send_random_mouse_move() {
    // 检查 USB 是否仍然挂载
    let mounted = unsafe {
        rust_is_usb_mounted()
    };
    
    if !mounted {
        log_info("USB not mounted, skipping mouse move");
        return;
    }
    
    // 生成随机的鼠标移动距离 (-10 到 10 之间)
    let random_x = (get_random_u32() % 21) as i8 - 10;
    let random_y = (get_random_u32() % 21) as i8 - 10;
    
    // 发送鼠标移动事件
    log_info("Sending mouse move event");
    unsafe {
        rust_send_mouse_report(REPORT_ID_MOUSE, 0, random_x, random_y, 0, 0);
    }
}

/// 获取随机数
fn get_random_u32() -> u32 {
    // 使用简单的线性同余生成器
    static mut SEED: u32 = 42;
    unsafe {
        SEED = SEED.wrapping_mul(1103515245).wrapping_add(12345);
        SEED
    }
}