#include "alfpriv.h"

/* LABEL */

typedef struct {
    DWORD style;
    HFONT font;
} ALFLabelPriv;

TCHAR *_alf_labelClass;

static int
ALF__LabelTopPadding(HWND hwnd)
{
    // some pixels on top to align with the edit control
    // see also: alfedit.cpp
    return ALF_Compat_GetSystemMetricsForDpi(
                SM_CYEDGE, (UINT)ALF_CentipointsToPixels(GetParent(hwnd), 7200))
            + (!ALF_Compat_IsMinWindowsVersion(4, 0) ? 2 : 1) /* internal padding in edit control */;
}

static int
ALF__LabelLeftPadding(HWND hwnd, HDC hdc)
{
    // some pixels on the left to align with the edit control
    // see also: alfedit.cpp
    int p = ALF_Compat_GetSystemMetricsForDpi(
                SM_CXEDGE, (UINT)ALF_CentipointsToPixels(GetParent(hwnd), 7200));

    p += 1;

    TEXTMETRIC tm;
    ZeroMemory(&tm, sizeof(tm));
    if (GetTextMetrics(hdc, &tm)) {
        if (tm.tmPitchAndFamily & (TMPF_VECTOR | TMPF_TRUETYPE))
            p += ALF_GetAveCharWidth(hdc) / 2;
    }

    return p;
}

static BOOL CALLBACK
ALF__Label_Text_DrawStateProc(HDC hdc, LPARAM lData, WPARAM wData, int cx, int cy)
{
    (void)wData;

    int oldBkMode = SetBkMode(hdc, TRANSPARENT);

    RECT r = { 0, 0, cx, cy };
    DrawText(hdc, (TCHAR*)lData, -1, &r, (UINT)wData);

    SetBkMode(hdc, oldBkMode);

    return TRUE;
}

static LRESULT CALLBACK
ALF__LabelWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    ALFLabelPriv *priv = (ALFLabelPriv*)GetWindowLongPtr(hwnd, 0);
    if (!priv)
        return DefWindowProc(hwnd, uMsg, wParam, lParam);

    if (uMsg == ALF_WM_LBL_GETSTYLE) {
        return (LRESULT)priv->style;
    } else if (uMsg == ALF_WM_LBL_SETSTYLE) {
        priv->style = (DWORD)lParam;
        InvalidateRect(hwnd, NULL, TRUE);
        return TRUE;
    } else if (uMsg == WM_SETTEXT) {
        InvalidateRect(hwnd, NULL, TRUE);
        ALF_InvalidateLayout(GetParent(hwnd));
    } else if (uMsg == WM_GETDLGCODE) {
        return DLGC_STATIC;
    } else if (uMsg == WM_SETFONT) {
        priv->font = (HFONT)wParam;
        if (LOWORD(lParam) != 0)
            InvalidateRect(hwnd, NULL, TRUE);

        ALF_InvalidateLayout(GetParent(hwnd));

        return 0;
    } else if (uMsg == WM_GETFONT) {
        return (LRESULT)priv->font;
    } else if (uMsg == WM_UPDATEUISTATE) {
        InvalidateRect(hwnd, NULL, TRUE);
    } else if (uMsg == WM_ERASEBKGND) {
        return 1; // do it in WM_PAINT
    } else if (uMsg == WM_PAINT) {
        PAINTSTRUCT ps;
        HDC hdc = BeginPaint(hwnd, &ps);

        ALF_Compat_DrawThemeParentBackground(hwnd, hdc, &ps.rcPaint);

        HFONT oldFont = NULL;
        if (priv->font)
            oldFont = SelectFont(hdc, priv->font);

        SetTextColor(hdc, GetSysColor(COLOR_BTNTEXT));
        SetBkMode(hdc, TRANSPARENT);

        // calc drawtext style
        UINT format = DT_EXPANDTABS;

        LRESULT uiState = SendMessage(hwnd, WM_QUERYUISTATE, 0, 0);
        if (uiState & UISF_HIDEACCEL)
            format |= DT_HIDEPREFIX;

        RECT rc;
        GetClientRect(hwnd, &rc);

        switch (priv->style & ALF_LABEL_HALIGN_MASK) {
            case ALF_LABEL_ALIGN_HCENTER:
                format |= DT_CENTER;
                break;
            case ALF_LABEL_ALIGN_RIGHT:
                format |= DT_RIGHT;
                break;
        }
        switch (priv->style & ALF_LABEL_VALIGN_MASK) {
            case ALF_LABEL_ALIGN_BOTTOM:
                format |= DT_BOTTOM;
                break;
            case ALF_LABEL_ALIGN_VCENTER:
                format |= DT_VCENTER;
                break;
        }

        if ((priv->style & ALF_LABEL_HALIGN_MASK) == ALF_LABEL_ALIGN_LEFT_LIKE_EDIT)
            rc.left += ALF__LabelLeftPadding(hwnd, hdc);
        if ((priv->style & ALF_LABEL_VALIGN_MASK) == ALF_LABEL_ALIGN_TOP_LIKE_EDIT)
            rc.top += ALF__LabelTopPadding(hwnd);

        TCHAR *text = ALF_Text(hwnd);

        if (!IsWindowEnabled(hwnd)) {
            if (!ALF_Compat_IsMinWindowsVersion(4, 0)) {
                // Win32s/NT 3.51 uses gray text, but a different gray than Win9x
                SetTextColor(hdc, GetSysColor(COLOR_BTNSHADOW));

                DrawText(hdc, text, -1, &rc, format);
            } else if (ALF_Compat_IsWin9x()) {
                // Win9x just uses gray text. DSS_DISABLED is broken there, too,
                // so we can't get the NT look even if we wanted to
                SetTextColor(hdc, GetSysColor(COLOR_GRAYTEXT));

                DrawText(hdc, text, -1, &rc, format);
            } else {
                // FIXME! This doesn't look good when using uxtheme, even though windows does it the same way
                // need to investigate whether drawing with disabled button style looks nicer
                DrawState(hdc, NULL,
                          ALF__Label_Text_DrawStateProc,
                          (LPARAM)text, (WPARAM)format,
                          rc.left,
                          rc.top,
                          rc.right - rc.left,
                          rc.bottom - rc.top,
                          DST_COMPLEX | DSS_DISABLED);
            }
        } else {
            DrawText(hdc, text, -1, &rc, format);
        }

        ALF_Free(text);

        if (oldFont)
            SelectFont(hdc, oldFont);

        EndPaint(hwnd, &ps);

        return TRUE;
    } else if (uMsg == ALF_WM_QUERYSIZE) {
        int textlen = GetWindowTextLength(hwnd);
        SIZE *pSize = (SIZE*)(void*)lParam;
        if (textlen) {
            HDC hdcLabel = GetDC(hwnd);
            HFONT oldFont = SelectFont(hdcLabel, priv->font);

            // calc drawtext style
            UINT format = DT_LEFT | DT_EXPANDTABS | DT_CALCRECT;

            RECT r = { 0, 0, 100, 100 };

            TCHAR *textbuf = ALF_New(TCHAR, (SIZE_T)textlen + 1);
            GetWindowText(hwnd, textbuf, textlen+1);

            DrawText(hdcLabel, textbuf, -1, &r, format);

            ALF_Free(textbuf);

            if (pSize->cx == 0) {
                pSize->cx = r.right - r.left;
                if ((priv->style & ALF_LABEL_HALIGN_MASK) == ALF_LABEL_ALIGN_LEFT_LIKE_EDIT)
                    pSize->cx += ALF__LabelLeftPadding(hwnd, hdcLabel);
            }
            if (pSize->cy == 0) {
                pSize->cy = r.bottom - r.top;
                if ((priv->style & ALF_LABEL_VALIGN_MASK) == ALF_LABEL_ALIGN_TOP_LIKE_EDIT)
                    pSize->cy += ALF__LabelTopPadding(hwnd);
            }

            SelectFont(hdcLabel, oldFont);

            ReleaseDC(hwnd, hdcLabel);
        }
    } else if (uMsg == WM_WINDOWPOSCHANGED) {
        WINDOWPOS *p = (WINDOWPOS *)lParam;
        if (!(p->flags & SWP_NOSIZE)) {
            // for left-top aligned labels, no redraw is necessary
            // right/bottom/center alignment basically needs to redraw the whole thing
            DWORD halign = priv->style & ALF_LABEL_HALIGN_MASK;
            DWORD valign = priv->style & ALF_LABEL_VALIGN_MASK;

            if ((halign != ALF_LABEL_ALIGN_LEFT && halign != ALF_LABEL_ALIGN_LEFT_LIKE_EDIT)
                    || (valign != ALF_LABEL_ALIGN_TOP && valign != ALF_LABEL_ALIGN_TOP_LIKE_EDIT)) {
                InvalidateRect(hwnd, NULL, TRUE);
            }
        }
    } else if (uMsg == WM_DESTROY) {
        ALF_Free(priv);
        SetWindowLongPtr(hwnd, 0, 0);
    }

    return DefWindowProc(hwnd, uMsg, wParam, lParam);
}

HWND
ALF_AddLabel(HWND win, WORD id, int x, int y, const TCHAR *text)
{
    HWND hwndLabel = CreateWindow(_alf_labelClass,
                                  text,
                                  WS_CHILD | WS_VISIBLE,
                                  0, 0, 100, 100,
                                  win,
                                  (HMENU)(int)id,
                                  ALF_HINSTANCE,
                                  NULL);

    ALFLabelPriv *priv = ALF_New(ALFLabelPriv, 1);
    priv->style = ALF_LABEL_ALIGN_LEFT | ALF_LABEL_ALIGN_TOP_LIKE_EDIT;
    SetWindowLongPtr(hwndLabel, 0, (LONG_PTR)priv);

    ALF_AddWidget(win, x, y, hwndLabel, 0, 0, ALF_LAYOUT_SIZE_QUERY | ALF_LAYOUT_INHERITFONT | ALF_LAYOUT_TRANSPARENTBG);

    return hwndLabel;
}


void
ALF_RegisterLabelClass(void)
{
    WNDCLASS cls;
    ZeroMemory(&cls, sizeof(cls));

    TCHAR  classNameBuf[256];
    ALF_BuildUniqueName(classNameBuf, TEXT("ALFLabel."), (ULONG_PTR)&_alf_labelClass);

    cls.hInstance = ALF_HINSTANCE;
    cls.hCursor = LoadCursor(NULL, (LPTSTR)IDC_ARROW);
    cls.lpszClassName = classNameBuf;
    cls.cbWndExtra = sizeof(void*);
    cls.lpfnWndProc = ALF__LabelWindowProc;

    ATOM classatom = RegisterClass(&cls);
    if (!classatom)
        MessageBox(NULL, TEXT("FATAL: Could not register label class"), NULL, MB_OK);

    _alf_labelClass = MAKEINTATOM(classatom);
}