/*
 * Copyright (C) 2007 Google (Evan Stade)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */

#include <stdarg.h>
#include <math.h>

#include "windef.h"
#include "winbase.h"
#include "winuser.h"
#include "wingdi.h"
#include "gdiplus.h"
#include "gdiplus_private.h"
#include "wine/debug.h"

/* looks-right constant */
#define TENSION_CONST (0.3)

static inline INT roundr(REAL x)
{
    return (INT) floor(x+0.5);
}

static inline REAL deg2rad(REAL degrees)
{
    return (M_PI*2.0) * degrees / 360.0;
}

/* Converts angle (in degrees) to x/y coordinates */
static void deg2xy(REAL angle, REAL x_0, REAL y_0, REAL *x, REAL *y)
{
    REAL radAngle, hypotenuse;

    radAngle = deg2rad(angle);
    hypotenuse = 50.0; /* arbitrary */

    *x = x_0 + cos(radAngle) * hypotenuse;
    *y = y_0 + sin(radAngle) * hypotenuse;
}

/* GdipDrawPie/GdipFillPie helper function */
static GpStatus draw_pie(GpGraphics *graphics, HBRUSH gdibrush, HPEN gdipen,
    REAL x, REAL y, REAL width, REAL height, REAL startAngle, REAL sweepAngle)
{
    HGDIOBJ old_pen, old_brush;
    REAL x_0, y_0, x_1, y_1, x_2, y_2;

    if(!graphics)
        return InvalidParameter;

    old_pen = SelectObject(graphics->hdc, gdipen);
    old_brush = SelectObject(graphics->hdc, gdibrush);

    x_0 = x + (width/2.0);
    y_0 = y + (height/2.0);

    deg2xy(startAngle+sweepAngle, x_0, y_0, &x_1, &y_1);
    deg2xy(startAngle, x_0, y_0, &x_2, &y_2);

    Pie(graphics->hdc, roundr(x), roundr(y), roundr(x+width), roundr(y+height),
        roundr(x_1), roundr(y_1), roundr(x_2), roundr(y_2));

    SelectObject(graphics->hdc, old_pen);
    SelectObject(graphics->hdc, old_brush);

    return Ok;
}

/* GdipDrawCurve helper function.
 * Calculates Bezier points from cardinal spline points. */
static void calc_curve_bezier(CONST GpPointF *pts, REAL tension, REAL *x1,
    REAL *y1, REAL *x2, REAL *y2)
{
    REAL xdiff, ydiff;

    /* calculate tangent */
    xdiff = pts[2].X - pts[0].X;
    ydiff = pts[2].Y - pts[0].Y;

    /* apply tangent to get control points */
    *x1 = pts[1].X - tension * xdiff;
    *y1 = pts[1].Y - tension * ydiff;
    *x2 = pts[1].X + tension * xdiff;
    *y2 = pts[1].Y + tension * ydiff;
}

/* GdipDrawCurve helper function.
 * Calculates Bezier points from cardinal spline endpoints. */
static void calc_curve_bezier_endp(REAL xend, REAL yend, REAL xadj, REAL yadj,
    REAL tension, REAL *x, REAL *y)
{
    /* tangent at endpoints is the line from the endpoint to the adjacent point */
    *x = roundr(tension * (xadj - xend) + xend);
    *y = roundr(tension * (yadj - yend) + yend);
}

GpStatus WINGDIPAPI GdipCreateFromHDC(HDC hdc, GpGraphics **graphics)
{
    if(hdc == NULL)
        return OutOfMemory;

    if(graphics == NULL)
        return InvalidParameter;

    *graphics = GdipAlloc(sizeof(GpGraphics));
    if(!*graphics)  return OutOfMemory;

    (*graphics)->hdc = hdc;
    (*graphics)->hwnd = NULL;

    return Ok;
}

GpStatus WINGDIPAPI GdipCreateFromHWND(HWND hwnd, GpGraphics **graphics)
{
    GpStatus ret;

    if((ret = GdipCreateFromHDC(GetDC(hwnd), graphics)) != Ok)
        return ret;

    (*graphics)->hwnd = hwnd;

    return Ok;
}

GpStatus WINGDIPAPI GdipDeleteGraphics(GpGraphics *graphics)
{
    if(!graphics) return InvalidParameter;
    if(graphics->hwnd)
        ReleaseDC(graphics->hwnd, graphics->hdc);

    HeapFree(GetProcessHeap(), 0, graphics);

    return Ok;
}

GpStatus WINGDIPAPI GdipDrawArc(GpGraphics *graphics, GpPen *pen, REAL x,
    REAL y, REAL width, REAL height, REAL startAngle, REAL sweepAngle)
{
    HGDIOBJ old_pen;
    REAL x_0, y_0, x_1, y_1, x_2, y_2;

    if(!graphics || !pen)
        return InvalidParameter;

    old_pen = SelectObject(graphics->hdc, pen->gdipen);

    x_0 = x + (width/2.0);
    y_0 = y + (height/2.0);

    deg2xy(startAngle+sweepAngle, x_0, y_0, &x_1, &y_1);
    deg2xy(startAngle, x_0, y_0, &x_2, &y_2);

    Arc(graphics->hdc, roundr(x), roundr(y), roundr(x+width), roundr(y+height),
        roundr(x_1), roundr(y_1), roundr(x_2), roundr(y_2));

    SelectObject(graphics->hdc, old_pen);

    return Ok;
}

GpStatus WINGDIPAPI GdipDrawBezier(GpGraphics *graphics, GpPen *pen, REAL x1,
    REAL y1, REAL x2, REAL y2, REAL x3, REAL y3, REAL x4, REAL y4)
{
    HGDIOBJ old_pen;
    POINT pt[4] = {{roundr(x1), roundr(y1)}, {roundr(x2), roundr(y2)},
                   {roundr(x3), roundr(y3)}, {roundr(x4), roundr(y4)}};

    if(!graphics || !pen)
        return InvalidParameter;

    old_pen = SelectObject(graphics->hdc, pen->gdipen);

    PolyBezier(graphics->hdc, pt, 4);

    SelectObject(graphics->hdc, old_pen);

    return Ok;
}

/* Approximates cardinal spline with Bezier curves. */
GpStatus WINGDIPAPI GdipDrawCurve2(GpGraphics *graphics, GpPen *pen,
    GDIPCONST GpPointF *points, INT count, REAL tension)
{
    HGDIOBJ old_pen;

    /* PolyBezier expects count*3-2 points. */
    int i, len_pt = count*3-2;
    POINT pt[len_pt];
    REAL x1, x2, y1, y2;

    if(!graphics || !pen)
        return InvalidParameter;

    tension = tension * TENSION_CONST;

    calc_curve_bezier_endp(points[0].X, points[0].Y, points[1].X, points[1].Y,
        tension, &x1, &y1);

    pt[0].x = roundr(points[0].X);
    pt[0].y = roundr(points[0].Y);
    pt[1].x = roundr(x1);
    pt[1].y = roundr(y1);

    for(i = 0; i < count-2; i++){
        calc_curve_bezier(&(points[i]), tension, &x1, &y1, &x2, &y2);

        pt[3*i+2].x = roundr(x1);
        pt[3*i+2].y = roundr(y1);
        pt[3*i+3].x = roundr(points[i+1].X);
        pt[3*i+3].y = roundr(points[i+1].Y);
        pt[3*i+4].x = roundr(x2);
        pt[3*i+4].y = roundr(y2);
    }

    calc_curve_bezier_endp(points[count-1].X, points[count-1].Y,
        points[count-2].X, points[count-2].Y, tension, &x1, &y1);

    pt[len_pt-2].x = x1;
    pt[len_pt-2].y = y1;
    pt[len_pt-1].x = roundr(points[count-1].X);
    pt[len_pt-1].y = roundr(points[count-1].Y);

    old_pen = SelectObject(graphics->hdc, pen->gdipen);

    PolyBezier(graphics->hdc, pt, len_pt);

    SelectObject(graphics->hdc, old_pen);

    return Ok;
}

GpStatus WINGDIPAPI GdipDrawLineI(GpGraphics *graphics, GpPen *pen, INT x1,
    INT y1, INT x2, INT y2)
{
    HGDIOBJ old_obj;

    if(!pen || !graphics)
        return InvalidParameter;

    old_obj = SelectObject(graphics->hdc, pen->gdipen);
    MoveToEx(graphics->hdc, x1, y1, NULL);
    LineTo(graphics->hdc, x2, y2);
    SelectObject(graphics->hdc, old_obj);

    return Ok;
}

GpStatus WINGDIPAPI GdipDrawLines(GpGraphics *graphics, GpPen *pen, GDIPCONST
    GpPointF *points, INT count)
{
    HGDIOBJ old_obj;
    INT i;

    if(!pen || !graphics || (count < 2))
        return InvalidParameter;

    old_obj = SelectObject(graphics->hdc, pen->gdipen);
    MoveToEx(graphics->hdc, roundr(points[0].X), roundr(points[0].Y), NULL);

    for(i = 1; i < count; i++){
        LineTo(graphics->hdc, roundr(points[i].X), roundr(points[i].Y));
    }

    SelectObject(graphics->hdc, old_obj);

    return Ok;
}

GpStatus WINGDIPAPI GdipDrawPie(GpGraphics *graphics, GpPen *pen, REAL x,
    REAL y, REAL width, REAL height, REAL startAngle, REAL sweepAngle)
{
    if(!pen)
        return InvalidParameter;

    return draw_pie(graphics, GetStockObject(NULL_BRUSH), pen->gdipen, x, y,
        width, height, startAngle, sweepAngle);
}

GpStatus WINGDIPAPI GdipDrawRectangleI(GpGraphics *graphics, GpPen *pen, INT x,
    INT y, INT width, INT height)
{
    LOGBRUSH lb;
    HPEN hpen;
    HGDIOBJ old_obj;

    if(!pen || !graphics)
        return InvalidParameter;

    lb.lbStyle = BS_SOLID;
    lb.lbColor = pen->color;
    lb.lbHatch = 0;

    hpen = ExtCreatePen(PS_GEOMETRIC | PS_ENDCAP_SQUARE, (INT) pen->width,
        &lb, 0, NULL);

    old_obj = SelectObject(graphics->hdc, hpen);

    /* assume pen aligment centered */
    MoveToEx(graphics->hdc, x, y, NULL);
    LineTo(graphics->hdc, x+width, y);
    LineTo(graphics->hdc, x+width, y+height);
    LineTo(graphics->hdc, x, y+height);
    LineTo(graphics->hdc, x, y);

    SelectObject(graphics->hdc, old_obj);
    DeleteObject(hpen);

    return Ok;
}

GpStatus WINGDIPAPI GdipFillPie(GpGraphics *graphics, GpBrush *brush, REAL x,
    REAL y, REAL width, REAL height, REAL startAngle, REAL sweepAngle)
{
    if(!brush)
        return InvalidParameter;

    return draw_pie(graphics, brush->gdibrush, GetStockObject(NULL_PEN), x, y,
        width, height, startAngle, sweepAngle);
}