#pragma version(1)

#pragma rs java_package_name(com.android.launcher2)

#include "rs_graphics.rsh"

#define PI 3.14159f

// Constants from Java
int COLUMNS_PER_PAGE_PORTRAIT;
int ROWS_PER_PAGE_PORTRAIT;
int COLUMNS_PER_PAGE_LANDSCAPE;
int ROWS_PER_PAGE_LANDSCAPE;

int gIconCount;
int gSelectedIconIndex = -1;
rs_allocation gSelectedIconTexture;
rs_allocation gHomeButton;

rs_program_fragment gPFTexNearest;
rs_program_fragment gPFTexMip;
rs_program_fragment gPFTexMipAlpha;
rs_program_vertex gPVCurve;
rs_program_store gPS;
rs_mesh gSMCell;

rs_allocation *gIcons;
rs_allocation *gLabels;

typedef struct VpConsts {
    rs_matrix4x4 Proj;
    float4 Position;
    float4 ScaleOffset;
    float2 BendPos;
    float2 ImgSize;
} VpConsts_t;
VpConsts_t *vpConstants;

// Attraction to center values from page edge to page center.
static float g_AttractionTable[9] = {20.f, 20.f, 20.f, 10.f, -10.f, -20.f, -20.f, -20.f, -20.f};
static float g_FrictionTable[9] = {10.f, 10.f, 11.f, 15.f, 15.f, 11.f, 10.f, 10.f, 10.f};
static float g_PhysicsTableSize = 7;

static float gZoomTarget;
float gTargetPos;
static float g_PosPage = 0.f;
static float g_PosVelocity = 0.f;
static float g_LastPositionX = 0.f;
static bool g_LastTouchDown = false;
static float g_DT;
static int g_PosMax;
static float g_Zoom = 0.f;
static float g_Animation = 1.f;
static float g_OldPosPage;
static float g_OldPosVelocity;
static float g_OldZoom;
static float g_MoveToTotalTime = 0.2f;
static float g_MoveToTime = 0.f;
static float g_MoveToOldPos = 0.f;

static int g_Cols;
static int g_Rows;

rs_allocation g_VPConstAlloc;

// Drawing constants, should be parameters ======
#define VIEW_ANGLE 1.28700222f


static void updateReadback() {
    if ((g_OldPosPage != g_PosPage) ||
        (g_OldPosVelocity != g_PosVelocity) ||
        (g_OldZoom != g_Zoom)) {

        g_OldPosPage = g_PosPage;
        g_OldPosVelocity = g_PosVelocity;
        g_OldZoom = g_Zoom;

        int i[3];
        i[0] = g_PosPage * (1 << 16);
        i[1] = g_PosVelocity * (1 << 16);
        i[2] = g_OldZoom * (1 << 16);
        rsSendToClientBlocking(1, &i[0], sizeof(i));
    }
}

void init() {
}

void move(float newPos) {
    if (g_LastTouchDown) {
        float dx = -(newPos - g_LastPositionX);
        g_PosVelocity = 0;
        g_PosPage += dx * 5.2f;

        float pmin = -0.49f;
        float pmax = g_PosMax + 0.49f;
        g_PosPage = clamp(g_PosPage, pmin, pmax);
    }
    g_LastTouchDown = true;
    g_LastPositionX = newPos;
    g_MoveToTime = 0;
}

void moveTo(float targetPos) {
    gTargetPos = targetPos;
    g_MoveToTime = g_MoveToTotalTime;
    g_PosVelocity = 0;
    g_MoveToOldPos = g_PosPage;
}

void setZoom(float z, /*bool*/ int animate) {
    gZoomTarget = z;
    if (gZoomTarget < 0.001f) {
        gZoomTarget = 0;
    }
    if (!animate) {
        g_Zoom = gZoomTarget;
    }
    updateReadback();
}

void fling(float newPos, float vel) {
    move(newPos);

    g_LastTouchDown = false;
    g_PosVelocity = -vel * 4;
    float av = fabs(g_PosVelocity);
    float minVel = 3.5f;

    minVel *= 1.f - (fabs(rsFrac(g_PosPage + 0.5f) - 0.5f) * 0.45f);

    if (av < minVel && av > 0.2f) {
        if (g_PosVelocity > 0) {
            g_PosVelocity = minVel;
        } else {
            g_PosVelocity = -minVel;
        }
    }

    if (g_PosPage <= 0) {
        g_PosVelocity = max(0.f, g_PosVelocity);
    }
    if (g_PosPage > g_PosMax) {
        g_PosVelocity = min(0.f, g_PosVelocity);
    }
}

// Interpolates values in the range 0..1 to a curve that eases in
// and out.
static float getInterpolation(float input) {
    return (cos((input + 1) * PI) * 0.5f) + 0.5f;
}


static void updatePos() {
    if (g_LastTouchDown) {
        return;
    }

    float tablePosNorm = rsFrac(g_PosPage + 0.5f);
    float tablePosF = tablePosNorm * g_PhysicsTableSize;
    int tablePosI = tablePosF;
    float tablePosFrac = tablePosF - tablePosI;
    float accel = mix(g_AttractionTable[tablePosI],
                        g_AttractionTable[tablePosI + 1],
                        tablePosFrac) * g_DT;
    float friction = mix(g_FrictionTable[tablePosI],
                        g_FrictionTable[tablePosI + 1],
                        tablePosFrac) * g_DT;

    if (g_MoveToTime) {
        // New position is old posiition + (total distance) * (interpolated time)
        g_PosPage = g_MoveToOldPos + (gTargetPos - g_MoveToOldPos) * getInterpolation((g_MoveToTotalTime - g_MoveToTime) / g_MoveToTotalTime);
        g_MoveToTime -= g_DT;
        if (g_MoveToTime <= 0) {
            g_MoveToTime = 0;
            g_PosPage = gTargetPos;
        }
        return;
    }

    // If our velocity is low OR acceleration is opposing it, apply it.
    if (fabs(g_PosVelocity) < 4.0f || (g_PosVelocity * accel) < 0) {
        g_PosVelocity += accel;
    }
    //RS_DEBUG(g_PosPage);
    //RS_DEBUG(g_PosVelocity);
    //RS_DEBUG(friction);
    //RS_DEBUG(accel);

    // Normal physics
    if (g_PosVelocity > 0) {
        g_PosVelocity -= friction;
        g_PosVelocity = max(g_PosVelocity, 0.f);
    } else {
        g_PosVelocity += friction;
        g_PosVelocity = min(g_PosVelocity, 0.f);
    }

    if ((friction > fabs(g_PosVelocity)) && (friction > fabs(accel))) {
        // Special get back to center and overcome friction physics.
        float t = tablePosNorm - 0.5f;
        if (fabs(t) < (friction * g_DT)) {
            // really close, just snap
            g_PosPage = round(g_PosPage);
            g_PosVelocity = 0;
        } else {
            if (t > 0) {
                g_PosVelocity = -friction;
            } else {
                g_PosVelocity = friction;
            }
        }
    }

    // Check for out of boundry conditions.
    if (g_PosPage < 0 && g_PosVelocity < 0) {
        float damp = 1.0f + (g_PosPage * 4);
        damp = clamp(damp, 0.f, 0.9f);
        g_PosVelocity *= damp;
    }
    if (g_PosPage > g_PosMax && g_PosVelocity > 0) {
        float damp = 1.0f - ((g_PosPage - g_PosMax) * 4);
        damp = clamp(damp, 0.f, 0.9f);
        g_PosVelocity *= damp;
    }

    g_PosPage += g_PosVelocity * g_DT;
    g_PosPage = clamp(g_PosPage, -0.49f, g_PosMax + 0.49f);
}

static void
draw_home_button()
{
    rsgBindTexture(gPFTexNearest, 0, gHomeButton);

    float w = rsgGetWidth();
    float h = rsgGetHeight();
    float tw = rsAllocationGetDimX(gHomeButton);
    float th = rsAllocationGetDimY(gHomeButton);

    float x;
    float y;
    if (w > h) {
        x = w - (tw * (1 - g_Animation)) + 20;
        y = (h - th) * 0.5f;
    } else {
        x = (w - tw) / 2;
        y = -g_Animation * th;
        y -= 30; // move the house to the edge of the screen as it doesn't fill the texture.
    }

    rsgDrawSpriteScreenspace(x, y, 0, tw, th);
}

static void drawFrontGrid(float rowOffset, float p)
{
    float h = rsgGetHeight();
    float w = rsgGetWidth();

    int intRowOffset = rowOffset;
    float rowFrac = rowOffset - intRowOffset;
    float colWidth = 120.f;//w / 4;
    float rowHeight = colWidth + 25.f;
    float yoff = 0.5f * h + 1.5f * rowHeight;

    int row, col;
    int colCount = 4;
    if (w > h) {
        colCount = 6;
        rowHeight -= 12.f;
        yoff = 0.47f * h + 1.0f * rowHeight;
    }

    int iconNum = (intRowOffset - 5) * colCount;

    rsgBindProgramVertex(gPVCurve);

    vpConstants->Position.z = p;

    for (row = -5; row < 15; row++) {
        float y = yoff - ((-rowFrac + row) * rowHeight);

        for (col=0; col < colCount; col++) {
            if (iconNum >= gIconCount) {
                return;
            }

            if (iconNum >= 0) {
                float x = colWidth * col + (colWidth / 2);
                vpConstants->Position.x = x + 0.2f;

                if (gSelectedIconIndex == iconNum && !p && rsIsObject(gSelectedIconTexture)) {
                    rsgBindProgramFragment(gPFTexNearest);
                    rsgBindTexture(gPFTexNearest, 0, gSelectedIconTexture);
                    vpConstants->ImgSize.x = rsAllocationGetDimX(gSelectedIconTexture);
                    vpConstants->ImgSize.y = rsAllocationGetDimY(gSelectedIconTexture);
                    vpConstants->Position.y = y - (rsAllocationGetDimY(gSelectedIconTexture)
                                                - rsAllocationGetDimY(gIcons[iconNum])) * 0.5f;
                    rsgAllocationSyncAll(g_VPConstAlloc);
                    rsgDrawMesh(gSMCell);
                }

                rsgBindProgramFragment(gPFTexMip);
                vpConstants->ImgSize.x = rsAllocationGetDimX(gIcons[iconNum]);
                vpConstants->ImgSize.y = rsAllocationGetDimY(gIcons[iconNum]);
                vpConstants->Position.y = y - 0.2f;
                rsgAllocationSyncAll(g_VPConstAlloc);
                rsgBindTexture(gPFTexMip, 0, gIcons[iconNum]);
                rsgDrawMesh(gSMCell);

                rsgBindProgramFragment(gPFTexMipAlpha);
                vpConstants->ImgSize.x = rsAllocationGetDimX(gLabels[iconNum]);
                vpConstants->ImgSize.y = rsAllocationGetDimY(gLabels[iconNum]);
                vpConstants->Position.y = y - 64.f - 0.2f;
                rsgAllocationSyncAll(g_VPConstAlloc);
                rsgBindTexture(gPFTexMipAlpha, 0, gLabels[iconNum]);
                rsgDrawMesh(gSMCell);
            }
            iconNum++;
        }
    }
}


int root()
{
    // Compute dt in seconds.
    // physics may break if DT is large.
    g_DT = min(rsGetDt(), 0.1f);
    g_VPConstAlloc = rsGetAllocation(vpConstants);

    if (g_Zoom != gZoomTarget) {
        float dz = g_DT * 1.7f;
        if (gZoomTarget < 0.5f) {
            dz = -dz;
        }
        if (fabs(g_Zoom - gZoomTarget) < fabs(dz)) {
            g_Zoom = gZoomTarget;
        } else {
            g_Zoom += dz;
        }
        updateReadback();
    }
    g_Animation = pow(1.f - g_Zoom, 3.f);

    // Set clear value to dim the background based on the zoom position.
    if ((g_Zoom < 0.001f) && (gZoomTarget < 0.001f)) {
        rsgClearColor(0.0f, 0.0f, 0.0f, 0.0f);
        // When we're zoomed out and not tracking motion events, reset the pos to 0.
        if (!g_LastTouchDown) {
            g_PosPage = 0;
        }
        return 0;
    } else {
        rsgClearColor(0.0f, 0.0f, 0.0f, g_Zoom);
    }

    rsgBindProgramStore(gPS);

    // icons & labels
    if (rsgGetWidth() > rsgGetHeight()) {
        g_Cols = COLUMNS_PER_PAGE_LANDSCAPE;
        g_Rows = ROWS_PER_PAGE_LANDSCAPE;
    } else {
        g_Cols = COLUMNS_PER_PAGE_PORTRAIT;
        g_Rows = ROWS_PER_PAGE_PORTRAIT;
    }

    g_PosMax = ((gIconCount + (g_Cols-1)) / g_Cols) - g_Rows;
    if (g_PosMax < 0) g_PosMax = 0;

    updatePos();
    updateReadback();

    // Draw the icons ========================================
    drawFrontGrid(g_PosPage, g_Animation);

    rsgBindProgramFragment(gPFTexNearest);
    draw_home_button();
    return (g_PosVelocity != 0) || rsFrac(g_PosPage) || g_Zoom != gZoomTarget || (g_MoveToTime != 0);
}