use helios_common::protocol::WindowInfo;

// ── Windows implementation ──────────────────────────────────────────────────

#[cfg(windows)]
mod win_impl {
    use super::*;
    use std::sync::Mutex;
    use windows::Win32::Foundation::{BOOL, HWND, LPARAM};
    use windows::Win32::UI::WindowsAndMessaging::{
        BringWindowToTop, EnumWindows, GetWindowTextW, IsWindowVisible, SetForegroundWindow,
        ShowWindow, SW_MAXIMIZE, SW_MINIMIZE, SW_RESTORE, SHOW_WINDOW_CMD,
    };
    use windows::Win32::UI::Input::KeyboardAndMouse::{
        keybd_event, KEYEVENTF_KEYUP, VK_MENU,
    };

    // Collect HWNDs via EnumWindows callback
    unsafe extern "system" fn enum_callback(hwnd: HWND, lparam: LPARAM) -> BOOL {
        let list = &mut *(lparam.0 as *mut Vec<HWND>);
        list.push(hwnd);
        BOOL(1)
    }

    fn get_all_hwnds() -> Vec<HWND> {
        let mut list: Vec<HWND> = Vec::new();
        unsafe {
            let _ = EnumWindows(
                Some(enum_callback),
                LPARAM(&mut list as *mut Vec<HWND> as isize),
            );
        }
        list
    }

    fn hwnd_title(hwnd: HWND) -> String {
        let mut buf = [0u16; 512];
        let len = unsafe { GetWindowTextW(hwnd, &mut buf) };
        String::from_utf16_lossy(&buf[..len as usize])
    }

    pub fn list_windows() -> Result<Vec<WindowInfo>, String> {
        let hwnds = get_all_hwnds();
        let mut windows = Vec::new();
        for hwnd in hwnds {
            let visible = unsafe { IsWindowVisible(hwnd).as_bool() };
            let title = hwnd_title(hwnd);
            // Only return visible windows with a non-empty title
            if !visible || title.is_empty() {
                continue;
            }
            windows.push(WindowInfo {
                id: hwnd.0 as u64,
                title,
                visible: true,
            });
        }
        Ok(windows)
    }

    pub fn minimize_all() -> Result<(), String> {
        let hwnds = get_all_hwnds();
        for hwnd in hwnds {
            let visible = unsafe { IsWindowVisible(hwnd).as_bool() };
            let title = hwnd_title(hwnd);
            if visible && !title.is_empty() {
                unsafe {
                    let _ = ShowWindow(hwnd, SW_MINIMIZE);
                }
            }
        }
        Ok(())
    }

    /// Bypass Windows Focus Stealing Prevention by sending a fake Alt keypress
    /// before calling SetForegroundWindow. Without this, SetForegroundWindow
    /// silently fails when the calling thread is not in the foreground.
    unsafe fn force_foreground(hwnd: HWND) {
        keybd_event(VK_MENU.0 as u8, 0, Default::default(), 0);
        keybd_event(VK_MENU.0 as u8, 0, KEYEVENTF_KEYUP, 0);
        ShowWindow(hwnd, SW_RESTORE);
        BringWindowToTop(hwnd).ok();
        SetForegroundWindow(hwnd);
    }

    pub fn focus_window(window_id: u64) -> Result<(), String> {
        let hwnd = HWND(window_id as isize);
        unsafe { force_foreground(hwnd); }
        Ok(())
    }

    pub fn maximize_and_focus(window_id: u64) -> Result<(), String> {
        let hwnd = HWND(window_id as isize);
        unsafe {
            ShowWindow(hwnd, SW_MAXIMIZE);
            force_foreground(hwnd);
        }
        Ok(())
    }
}

// ── Non-Windows stubs ───────────────────────────────────────────────────────

#[cfg(not(windows))]
mod win_impl {
    use super::*;

    pub fn list_windows() -> Result<Vec<WindowInfo>, String> {
        Err("Window management is only supported on Windows".to_string())
    }

    pub fn minimize_all() -> Result<(), String> {
        Err("Window management is only supported on Windows".to_string())
    }

    pub fn focus_window(_window_id: u64) -> Result<(), String> {
        Err("Window management is only supported on Windows".to_string())
    }

    pub fn maximize_and_focus(_window_id: u64) -> Result<(), String> {
        Err("Window management is only supported on Windows".to_string())
    }
}

// ── Public API ──────────────────────────────────────────────────────────────

pub fn list_windows() -> Result<Vec<WindowInfo>, String> {
    win_impl::list_windows()
}

pub fn minimize_all() -> Result<(), String> {
    win_impl::minimize_all()
}

pub fn focus_window(window_id: u64) -> Result<(), String> {
    win_impl::focus_window(window_id)
}

pub fn maximize_and_focus(window_id: u64) -> Result<(), String> {
    win_impl::maximize_and_focus(window_id)
}