"""Game window enumeration + capture.

On Windows we use pygetwindow to list visible top-level windows by title
and pywin32 (PrintWindow) to grab a single window — that works even when
the window is partially covered or not focused, which a regular mss screen
grab does not.

On non-Windows we degrade gracefully: list_windows() returns []  and
capture_window() falls back to a full-screen grab via mss. This is mostly
so the GUI imports cleanly during dev on Linux — actual gameplay
recognition is a Windows-only feature.
"""

from __future__ import annotations

import platform
import sys
from dataclasses import dataclass
from typing import List, Optional

from PIL import Image


@dataclass
class WindowInfo:
    handle: int  # HWND on Windows, 0 elsewhere
    title: str
    left: int
    top: int
    width: int
    height: int


def _is_windows() -> bool:
    return platform.system() == "Windows"


def list_windows() -> List[WindowInfo]:
    """Return visible top-level windows with a title. Windows-only; [] otherwise."""
    if not _is_windows():
        return []
    try:
        import pygetwindow as gw  # type: ignore
    except Exception:
        return []
    out: List[WindowInfo] = []
    for w in gw.getAllWindows():
        try:
            if not w.title:
                continue
            if w.width <= 50 or w.height <= 50:
                continue
            if not w.visible:
                continue
        except Exception:
            continue
        try:
            out.append(WindowInfo(
                handle=int(w._hWnd) if hasattr(w, "_hWnd") else 0,
                title=w.title,
                left=w.left, top=w.top,
                width=w.width, height=w.height,
            ))
        except Exception:
            continue
    return out


def find_sephiria() -> Optional[WindowInfo]:
    """Best-effort: pick the first window whose title contains 'Sephiria' / '세피리아'."""
    for w in list_windows():
        t = w.title.lower()
        if "sephiria" in t or "세피리아" in w.title:
            return w
    return None


def capture_window(info: WindowInfo) -> Image.Image:
    """Capture a single window into a PIL RGB image.

    On Windows uses PrintWindow with PW_RENDERFULLCONTENT (works on hidden
    windows / behind-other-windows). On other OSes falls back to an mss
    region grab of the window's bounding rectangle on the primary monitor.
    """
    if _is_windows() and info.handle:
        try:
            return _capture_window_win(info)
        except Exception:
            pass
    # Fallback: mss region grab
    return _capture_region_mss(info.left, info.top, info.width, info.height)


def _capture_window_win(info: WindowInfo) -> Image.Image:
    import ctypes
    from ctypes import wintypes

    hwnd = info.handle
    user32 = ctypes.windll.user32
    gdi32 = ctypes.windll.gdi32

    # Use the actual client/window rect — pygetwindow's width/height can
    # include shadow/DWM regions; GetWindowRect is more reliable.
    rect = wintypes.RECT()
    user32.GetWindowRect(hwnd, ctypes.byref(rect))
    width = rect.right - rect.left
    height = rect.bottom - rect.top
    if width <= 0 or height <= 0:
        raise RuntimeError("window has zero size")

    hwndDC = user32.GetWindowDC(hwnd)
    mfcDC = gdi32.CreateCompatibleDC(hwndDC)
    bitmap = gdi32.CreateCompatibleBitmap(hwndDC, width, height)
    gdi32.SelectObject(mfcDC, bitmap)

    PW_RENDERFULLCONTENT = 0x00000002
    ok = user32.PrintWindow(hwnd, mfcDC, PW_RENDERFULLCONTENT)

    # Read pixels
    class BITMAPINFOHEADER(ctypes.Structure):
        _fields_ = [
            ("biSize", wintypes.DWORD),
            ("biWidth", ctypes.c_long),
            ("biHeight", ctypes.c_long),
            ("biPlanes", wintypes.WORD),
            ("biBitCount", wintypes.WORD),
            ("biCompression", wintypes.DWORD),
            ("biSizeImage", wintypes.DWORD),
            ("biXPelsPerMeter", ctypes.c_long),
            ("biYPelsPerMeter", ctypes.c_long),
            ("biClrUsed", wintypes.DWORD),
            ("biClrImportant", wintypes.DWORD),
        ]

    class BITMAPINFO(ctypes.Structure):
        _fields_ = [("bmiHeader", BITMAPINFOHEADER), ("bmiColors", wintypes.DWORD * 3)]

    bmi = BITMAPINFO()
    bmi.bmiHeader.biSize = ctypes.sizeof(BITMAPINFOHEADER)
    bmi.bmiHeader.biWidth = width
    bmi.bmiHeader.biHeight = -height  # top-down
    bmi.bmiHeader.biPlanes = 1
    bmi.bmiHeader.biBitCount = 32
    bmi.bmiHeader.biCompression = 0  # BI_RGB

    buffer = ctypes.create_string_buffer(width * height * 4)
    gdi32.GetDIBits(mfcDC, bitmap, 0, height, buffer, ctypes.byref(bmi), 0)

    gdi32.DeleteObject(bitmap)
    gdi32.DeleteDC(mfcDC)
    user32.ReleaseDC(hwnd, hwndDC)

    img = Image.frombuffer("RGBA", (width, height), buffer, "raw", "BGRA", 0, 1)
    return img.convert("RGB")


def _capture_region_mss(left: int, top: int, width: int, height: int) -> Image.Image:
    import mss
    with mss.mss() as sct:
        region = {"left": left, "top": top, "width": width, "height": height}
        shot = sct.grab(region)
        img = Image.frombytes("RGB", shot.size, shot.bgra, "raw", "BGRX")
    return img