// platform_win32.c — Win32 windowing, input, clipboard, and process spawning

#include "platform/platform.h"

#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <windows.h>
#include <malloc.h>
#include <stdlib.h>
#include <string.h>

////////////////////////////////
// Window internals

struct PlatformWindow {
    HWND                  hwnd;
    B32                   should_close;
    S32                   width;
    S32                   height;
    PlatformFrameCallback frame_callback;
    void                 *frame_callback_user_data;
    PlatformRawInput      input;
    B32                   prev_mouse_down;
};

static PlatformWindow *g_main_window = NULL;
static B32 g_wndclass_registered = false;

////////////////////////////////
// Window procedure

// Forward declare ImGui Win32 handler (defined in imgui_impl_win32.cpp)
extern LRESULT ImGui_ImplWin32_WndProcHandler(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);

static LRESULT CALLBACK platform_wndproc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam) {
    // Let ImGui process input first
    if (ImGui_ImplWin32_WndProcHandler(hwnd, msg, wparam, lparam))
        return true;

    PlatformWindow *pw = (PlatformWindow *)GetWindowLongPtr(hwnd, GWLP_USERDATA);

    switch (msg) {
    case WM_SIZE:
        if (pw && wparam != SIZE_MINIMIZED) {
            pw->width  = (S32)LOWORD(lparam);
            pw->height = (S32)HIWORD(lparam);
            if (pw->frame_callback)
                pw->frame_callback(pw->frame_callback_user_data);
        }
        return 0;
    case WM_CHAR:
        if (pw && wparam >= 32 && wparam < 0xFFFF) {
            PlatformRawInput *ev = &pw->input;
            if (ev->char_count < PLATFORM_MAX_CHARS_PER_FRAME)
                ev->chars[ev->char_count++] = (U16)wparam;
        }
        return 0;
    case WM_KEYDOWN:
    case WM_SYSKEYDOWN:
        if (pw) {
            PlatformRawInput *ev = &pw->input;
            if (ev->key_count < PLATFORM_MAX_KEYS_PER_FRAME)
                ev->keys[ev->key_count++] = (U8)wparam;
            ev->ctrl_held  = (GetKeyState(VK_CONTROL) & 0x8000) != 0;
            ev->shift_held = (GetKeyState(VK_SHIFT) & 0x8000) != 0;
        }
        break;
    case WM_MOUSEWHEEL:
        if (pw) {
            S16 wheel_delta = (S16)HIWORD(wparam);
            pw->input.scroll_delta.y += (F32)wheel_delta / (F32)WHEEL_DELTA * 6.0f;
        }
        return 0;
    case WM_SETCURSOR:
        if (LOWORD(lparam) == HTCLIENT) {
            SetCursor(LoadCursor(NULL, IDC_IBEAM));
            return TRUE;
        }
        break;
    case WM_DPICHANGED:
        if (pw) {
            RECT *suggested = (RECT *)lparam;
            SetWindowPos(hwnd, NULL, suggested->left, suggested->top,
                suggested->right - suggested->left, suggested->bottom - suggested->top,
                SWP_NOZORDER | SWP_NOACTIVATE);
        }
        return 0;
    case WM_CLOSE:
        if (pw) pw->should_close = true;
        return 0;
    case WM_DESTROY:
        if (pw == g_main_window)
            PostQuitMessage(0);
        return 0;
    case WM_SYSCOMMAND:
        if ((wparam & 0xfff0) == SC_KEYMENU)
            return 0;
        break;
    }
    return DefWindowProcW(hwnd, msg, wparam, lparam);
}

////////////////////////////////
// Window lifecycle

PlatformWindow *platform_create_window(PlatformWindowDesc *desc) {
    SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2);

    if (!g_wndclass_registered) {
        WNDCLASSEXW wc = {0};
        wc.cbSize        = sizeof(wc);
        wc.style         = CS_CLASSDC;
        wc.lpfnWndProc   = platform_wndproc;
        wc.hInstance     = GetModuleHandleW(NULL);
        wc.hIcon         = LoadIconW(wc.hInstance, MAKEINTRESOURCEW(101));
        wc.hIconSm       = LoadIconW(wc.hInstance, MAKEINTRESOURCEW(101));
        wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
        wc.lpszClassName = L"codemax_wc";
        RegisterClassExW(&wc);
        g_wndclass_registered = true;
    }

    UINT dpi = GetDpiForSystem();
    int screen_w = GetSystemMetrics(SM_CXSCREEN);
    int screen_h = GetSystemMetrics(SM_CYSCREEN);
    int x = (screen_w - desc->width) / 2;
    int y = (screen_h - desc->height) / 2;

    DWORD style = WS_OVERLAPPEDWINDOW;
    RECT rect = { 0, 0, (LONG)desc->width, (LONG)desc->height };
    AdjustWindowRectExForDpi(&rect, style, FALSE, 0, dpi);

    int wchar_count = MultiByteToWideChar(CP_UTF8, 0, desc->title, -1, NULL, 0);
    wchar_t *wtitle = (wchar_t *)_malloca(wchar_count * sizeof(wchar_t));
    MultiByteToWideChar(CP_UTF8, 0, desc->title, -1, wtitle, wchar_count);

    HWND hwnd = CreateWindowExW(
        0, L"codemax_wc", wtitle,
        style,
        x, y,
        rect.right - rect.left,
        rect.bottom - rect.top,
        NULL, NULL, GetModuleHandleW(NULL), NULL
    );
    _freea(wtitle);

    if (!hwnd) return NULL;

    PlatformWindow *window = (PlatformWindow *)calloc(1, sizeof(PlatformWindow));
    window->hwnd         = hwnd;
    window->should_close = false;
    window->width        = desc->width;
    window->height       = desc->height;

    SetWindowLongPtr(hwnd, GWLP_USERDATA, (LONG_PTR)window);
    g_main_window = window;

    ShowWindow(hwnd, SW_SHOWDEFAULT);
    UpdateWindow(hwnd);
    return window;
}

void platform_destroy_window(PlatformWindow *window) {
    if (!window) return;
    if (window->hwnd) DestroyWindow(window->hwnd);
    if (g_main_window == window) g_main_window = NULL;
    free(window);
}

B32 platform_poll_events(PlatformWindow *window) {
    MSG msg;
    while (PeekMessageW(&msg, NULL, 0, 0, PM_REMOVE)) {
        TranslateMessage(&msg);
        DispatchMessageW(&msg);
        if (msg.message == WM_QUIT)
            window->should_close = true;
    }
    return !window->should_close;
}

void platform_get_size(PlatformWindow *window, S32 *w, S32 *h) {
    if (w) *w = window->width;
    if (h) *h = window->height;
}

void *platform_get_native_handle(PlatformWindow *window) {
    return (void *)window->hwnd;
}

PlatformRawInput platform_get_input(PlatformWindow *window) {
    PlatformRawInput result = window->input;

    POINT cursor;
    GetCursorPos(&cursor);
    ScreenToClient(window->hwnd, &cursor);
    result.mouse_pos = v2f32((F32)cursor.x, (F32)cursor.y);

    result.was_mouse_down = window->prev_mouse_down;
    result.mouse_down = (GetAsyncKeyState(VK_LBUTTON) & 0x8000) != 0;
    window->prev_mouse_down = result.mouse_down;

    memset(&window->input, 0, sizeof(window->input));
    return result;
}

void platform_set_frame_callback(PlatformWindow *window, PlatformFrameCallback cb, void *user_data) {
    window->frame_callback = cb;
    window->frame_callback_user_data = user_data;
}

F32 platform_get_dpi_scale(PlatformWindow *window) {
    if (!window || !window->hwnd) return 1.0f;
    return (F32)GetDpiForWindow(window->hwnd) / 96.0f;
}

////////////////////////////////
// Input adapter

PlatformInput platform_adapt_input(PlatformRawInput *raw) {
    PlatformInput pi = {0};
    pi.ctrl_held = raw->ctrl_held;
    pi.shift_held = raw->shift_held;
    pi.alt_held = (GetKeyState(VK_MENU) & 0x8000) != 0;

    // Convert UTF-16 chars to ASCII (printable range only)
    for (S32 i = 0; i < raw->char_count && pi.char_count < PLATFORM_MAX_CHARS_PER_FRAME; i++) {
        U16 ch = raw->chars[i];
        if (ch >= 32 && ch < 127)
            pi.chars[pi.char_count++] = (char)ch;
    }

    // Key codes are identical (both use Windows VK codes)
    for (S32 i = 0; i < raw->key_count && pi.key_count < PLATFORM_MAX_KEYS_PER_FRAME; i++)
        pi.keys[pi.key_count++] = raw->keys[i];

    return pi;
}

////////////////////////////////
// Clipboard

void platform_clipboard_set(const char *text) {
    if (!text) return;
    int len = (int)strlen(text);
    if (len == 0) return;
    int wlen = MultiByteToWideChar(CP_UTF8, 0, text, len, NULL, 0);
    if (wlen == 0) return;
    HGLOBAL hmem = GlobalAlloc(GMEM_MOVEABLE, (wlen + 1) * sizeof(wchar_t));
    if (!hmem) return;
    wchar_t *wbuf = (wchar_t *)GlobalLock(hmem);
    MultiByteToWideChar(CP_UTF8, 0, text, len, wbuf, wlen);
    wbuf[wlen] = L'\0';
    GlobalUnlock(hmem);
    HWND hwnd = g_main_window ? g_main_window->hwnd : NULL;
    if (OpenClipboard(hwnd)) {
        EmptyClipboard();
        SetClipboardData(CF_UNICODETEXT, hmem);
        CloseClipboard();
    } else {
        GlobalFree(hmem);
    }
}

const char *platform_clipboard_get(void) {
    static char buf[64 * 1024];
    buf[0] = '\0';
    HWND hwnd = g_main_window ? g_main_window->hwnd : NULL;
    if (!OpenClipboard(hwnd)) return NULL;
    HGLOBAL hmem = GetClipboardData(CF_UNICODETEXT);
    if (hmem) {
        wchar_t *wbuf = (wchar_t *)GlobalLock(hmem);
        if (wbuf) {
            int len = WideCharToMultiByte(CP_UTF8, 0, wbuf, -1, buf, sizeof(buf) - 1, NULL, NULL);
            buf[len > 0 ? len - 1 : 0] = '\0';
            GlobalUnlock(hmem);
        }
    }
    CloseClipboard();
    return buf[0] ? buf : NULL;
}

////////////////////////////////
// Process spawning

void platform_spawn_terminal(const char *command, const char *working_dir) {
    char cmd_line[2048];
    snprintf(cmd_line, sizeof(cmd_line), "cmd.exe /k %s", command);

    STARTUPINFOA si = {0};
    si.cb = sizeof(si);
    PROCESS_INFORMATION pi = {0};
    CreateProcessA(NULL, cmd_line, NULL, NULL, FALSE,
                   CREATE_NEW_CONSOLE, NULL, working_dir, &si, &pi);
    if (pi.hProcess) CloseHandle(pi.hProcess);
    if (pi.hThread) CloseHandle(pi.hThread);
}