// 进程管理：启进程、关闭窗口、强杀
use std::path::Path;

use windows_sys::Win32::Foundation::HWND;
use windows_sys::Win32::System::Threading::{
    OpenProcess, TerminateProcess, WaitForSingleObject, PROCESS_TERMINATE, PROCESS_VM_READ,
};
use windows_sys::Win32::UI::WindowsAndMessaging::{
    EnumWindows, GetWindowThreadProcessId, PostMessageW, WM_CLOSE,
};

use std::cell::RefCell;

thread_local! {
    static ENUM_RESULT: RefCell<EnumResult> = RefCell::new(EnumResult { hwnd: std::ptr::null_mut(), pid: 0 });
}
struct EnumResult { hwnd: HWND, pid: u32 }

unsafe extern "system" fn enum_callback(hwnd: HWND, _lparam: isize) -> i32 {
    let mut proc_id: u32 = 0;
    GetWindowThreadProcessId(hwnd, &mut proc_id);
    ENUM_RESULT.with(|r| {
        *r.borrow_mut() = EnumResult { hwnd, pid: proc_id };
    });
    1 // continue
}

/// 启动的子进程
pub struct Child {
    pub pid: u32,
    pub _handle: Option<std::process::Child>,
}

unsafe impl Send for Child {}
unsafe impl Sync for Child {}

/// 启动外部进程
pub fn spawn(exe: &Path, args: &str) -> anyhow::Result<Child> {
    let mut cmd = std::process::Command::new(exe);
    for arg in args.split_whitespace() {
        cmd.arg(arg.trim_matches('"'));
    }
    let child = cmd.spawn().map_err(|e| anyhow::anyhow!("启动 {:?} 失败：{}", exe, e))?;
    Ok(Child { pid: child.id(), _handle: Some(child) })
}

/// 通过 PID 找到主窗口 HWND
pub fn find_hwnd_by_pid(pid: u32) -> Option<HWND> {
    unsafe {
        let _ = EnumWindows(Some(enum_callback), 0);
    }
    let r = ENUM_RESULT.with(|r| r.borrow().hwnd);
    let p = ENUM_RESULT.with(|r| r.borrow().pid);
    if p == pid && !r.is_null() { Some(r) } else { None }
}

/// 优雅关闭：PostMessage WM_CLOSE 给主窗口 → 等待 → taskkill
pub fn close(child: &Child, cfg: &crate::config::ViewerSettings) -> anyhow::Result<()> {
    if let Some(hwnd) = find_hwnd_by_pid(child.pid) {
        unsafe {
            PostMessageW(hwnd, WM_CLOSE, 0, 0);
        }
        std::thread::sleep(std::time::Duration::from_millis(cfg.close_wait_ms));
    }
    if is_running(child.pid) {
        kill(child.pid);
    }
    Ok(())
}

/// 进程是否仍在运行
pub fn is_running(pid: u32) -> bool {
    unsafe {
        let h = OpenProcess(PROCESS_VM_READ, 0, pid);
        if h.is_null() { return false; }
        let r = WaitForSingleObject(h, 0);
        windows_sys::Win32::Foundation::CloseHandle(h);
        r != 0
    }
}

/// 强杀
pub fn kill(pid: u32) {
    unsafe {
        let h = OpenProcess(PROCESS_TERMINATE, 0, pid);
        if !h.is_null() {
            TerminateProcess(h, 1);
            windows_sys::Win32::Foundation::CloseHandle(h);
        }
        let _ = std::process::Command::new("taskkill")
            .arg("/F").arg("/PID").arg(pid.to_string()).arg("/T")
            .output();
    }
}