/*
 * 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"

WINE_DEFAULT_DEBUG_CHANNEL(gdiplus);

/* looks-right constants */
#define TENSION_CONST (0.3)
#define ANCHOR_WIDTH (2.0)

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);
}

/* Draws the linecap the specified color and size on the hdc.  The linecap is in
 * direction of the line from x1, y1 to x2, y2 and is anchored on x2, y2. */
static void draw_cap(HDC hdc, COLORREF color, GpLineCap cap, REAL size,
    REAL x1, REAL y1, REAL x2, REAL y2)
{
    HGDIOBJ oldbrush, oldpen;
    HBRUSH brush;
    HPEN pen;
    POINT pt[4];
    REAL theta, dsmall, dbig, dx, dy, invert;

    if(x2 != x1)
        theta = atan((y2 - y1) / (x2 - x1));
    else if(y2 != y1){
        theta = M_PI_2 * (y2 > y1 ? 1.0 : -1.0);
    }
    else
        return;

    invert = ((x2 - x1) >= 0.0 ? 1.0 : -1.0);
    brush = CreateSolidBrush(color);
    pen = CreatePen(PS_SOLID, 1, color);
    oldbrush = SelectObject(hdc, brush);
    oldpen = SelectObject(hdc, pen);

    switch(cap){
        case LineCapFlat:
            break;
        case LineCapSquare:
        case LineCapSquareAnchor:
        case LineCapDiamondAnchor:
            size = size * (cap & LineCapNoAnchor ? ANCHOR_WIDTH : 1.0) / 2.0;
            if(cap == LineCapDiamondAnchor){
                dsmall = cos(theta + M_PI_2) * size;
                dbig = sin(theta + M_PI_2) * size;
            }
            else{
                dsmall = cos(theta + M_PI_4) * size;
                dbig = sin(theta + M_PI_4) * size;
            }

            /* calculating the latter points from the earlier points makes them
             * look a little better because of rounding issues */
            pt[0].x = roundr(x2 - dsmall);
            pt[1].x = roundr(((REAL)pt[0].x) + dbig + dsmall);

            pt[0].y = roundr(y2 - dbig);
            pt[3].y = roundr(((REAL)pt[0].y) + dsmall + dbig);

            pt[1].y = roundr(y2 - dsmall);
            pt[2].y = roundr(dbig + dsmall + ((REAL)pt[1].y));

            pt[3].x = roundr(x2 - dbig);
            pt[2].x = roundr(((REAL)pt[3].x) + dsmall + dbig);

            Polygon(hdc, pt, 4);

            break;
        case LineCapArrowAnchor:
            size = size * 4.0 / sqrt(3.0);

            dx = cos(M_PI / 6.0 + theta) * size * invert;
            dy = sin(M_PI / 6.0 + theta) * size * invert;

            pt[0].x = roundr(x2 - dx);
            pt[0].y = roundr(y2 - dy);

            dx = cos(- M_PI / 6.0 + theta) * size * invert;
            dy = sin(- M_PI / 6.0 + theta) * size * invert;

            pt[1].x = roundr(x2 - dx);
            pt[1].y = roundr(y2 - dy);

            pt[2].x = roundr(x2);
            pt[2].y = roundr(y2);

            Polygon(hdc, pt, 3);

            break;
        case LineCapRoundAnchor:
            dx = dy = ANCHOR_WIDTH * size / 2.0;

            x2 = (REAL) roundr(x2 - dx);
            y2 = (REAL) roundr(y2 - dy);

            Ellipse(hdc, (INT) x2, (INT) y2, roundr(x2 + 2.0 * dx),
                roundr(y2 + 2.0 * dy));
            break;
        case LineCapTriangle:
            size = size / 2.0;
            dx = cos(M_PI_2 + theta) * size;
            dy = sin(M_PI_2 + theta) * size;

            /* Using roundr here can make the triangle float off the end of the
             * line. */
            pt[0].x = ((x2 - x1) >= 0 ? floor(x2 - dx) : ceil(x2 - dx));
            pt[0].y = ((y2 - y1) >= 0 ? floor(y2 - dy) : ceil(y2 - dy));
            pt[1].x = roundr(pt[0].x + 2.0 * dx);
            pt[1].y = roundr(pt[0].y + 2.0 * dy);

            dx = cos(theta) * size * invert;
            dy = sin(theta) * size * invert;

            pt[2].x = roundr(x2 + dx);
            pt[2].y = roundr(y2 + dy);

            Polygon(hdc, pt, 3);

            break;
        case LineCapRound:
            dx = -cos(M_PI_2 + theta) * size * invert;
            dy = -sin(M_PI_2 + theta) * size * invert;

            pt[0].x = ((x2 - x1) >= 0 ? floor(x2 - dx) : ceil(x2 - dx));
            pt[0].y = ((y2 - y1) >= 0 ? floor(y2 - dy) : ceil(y2 - dy));
            pt[1].x = roundr(pt[0].x + 2.0 * dx);
            pt[1].y = roundr(pt[0].y + 2.0 * dy);

            dx = dy = size / 2.0;

            x2 = (REAL) roundr(x2 - dx);
            y2 = (REAL) roundr(y2 - dy);

            Pie(hdc, (INT) x2, (INT) y2, roundr(x2 + 2.0 * dx),
                roundr(y2 + 2.0 * dy), pt[0].x, pt[0].y, pt[1].x, pt[1].y);
            break;
        case LineCapCustom:
            FIXME("line cap not implemented\n");
        default:
            break;
    }

    SelectObject(hdc, oldbrush);
    SelectObject(hdc, oldpen);
    DeleteObject(brush);
    DeleteObject(pen);
}

/* Shortens the line by the given percent by changing x2, y2.
 * If percent is > 1.0 then the line will change direction. */
static void shorten_line_percent(REAL x1, REAL  y1, REAL *x2, REAL *y2, REAL percent)
{
    REAL dist, theta, dx, dy;

    if((y1 == *y2) && (x1 == *x2))
        return;

    dist = sqrt((*x2 - x1) * (*x2 - x1) + (*y2 - y1) * (*y2 - y1)) * percent;
    theta = (*x2 == x1 ? M_PI_2 : atan((*y2 - y1) / (*x2 - x1)));
    dx = cos(theta) * dist;
    dy = sin(theta) * dist;

    *x2 = *x2 + fabs(dx) * (*x2 > x1 ? -1.0 : 1.0);
    *y2 = *y2 + fabs(dy) * (*y2 > y1 ? -1.0 : 1.0);
}

/* Shortens the line by the given amount by changing x2, y2.
 * If the amount is greater than the distance, the line will become length 0. */
static void shorten_line_amt(REAL x1, REAL y1, REAL *x2, REAL *y2, REAL amt)
{
    REAL dx, dy, percent;

    dx = *x2 - x1;
    dy = *y2 - y1;
    if(dx == 0 && dy == 0)
        return;

    percent = amt / sqrt(dx * dx + dy * dy);
    if(percent >= 1.0){
        *x2 = x1;
        *y2 = y1;
        return;
    }

    shorten_line_percent(x1, y1, x2, y2, percent);
}

/* Draws lines between the given points, and if caps is true then draws an endcap
 * at the end of the last line.  FIXME: Startcaps not implemented. */
static void draw_polyline(HDC hdc, GpPen *pen, GDIPCONST GpPointF * pt,
    INT count, BOOL caps)
{
    POINT *pti = GdipAlloc(count * sizeof(POINT));
    REAL x = pt[count - 1].X, y = pt[count - 1].Y;
    INT i;

    if(caps){
        if(pen->endcap == LineCapArrowAnchor)
            shorten_line_amt(pt[count-2].X, pt[count-2].Y, &x, &y, pen->width);

        draw_cap(hdc, pen->color, pen->endcap, pen->width, pt[count-2].X,
            pt[count-2].Y, pt[count - 1].X, pt[count - 1].Y);
    }

    for(i = 0; i < count - 1; i ++){
        pti[i].x = roundr(pt[i].X);
        pti[i].y = roundr(pt[i].Y);
    }

    pti[i].x = roundr(x);
    pti[i].y = roundr(y);

    Polyline(hdc, pti, count);
    GdipFree(pti);
}

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)
{
    INT save_state;
    GpPointF pt[2];

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

    pt[0].X = (REAL)x1;
    pt[0].Y = (REAL)y1;
    pt[1].X = (REAL)x2;
    pt[1].Y = (REAL)y2;

    save_state = SaveDC(graphics->hdc);
    EndPath(graphics->hdc);
    SelectObject(graphics->hdc, pen->gdipen);

    draw_polyline(graphics->hdc, pen, pt, 2, TRUE);

    RestoreDC(graphics->hdc, save_state);

    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);
}