/*
 * Copyright (c) 2019, 2021, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

#include <stdlib.h>
#include <string.h>

#include "sun_java2d_SunGraphics2D.h"

#include "MTLPaints.h"
#include "MTLVertexCache.h"
#include "MTLTexturePool.h"
#include "MTLTextRenderer.h"
#include "common.h"

typedef struct _J2DVertex {
    float position[2];
    float txtpos[2];
} J2DVertex;

static J2DVertex *vertexCache = NULL;
static jint vertexCacheIndex = 0;

static MTLPooledTextureHandle * maskCacheTex = NULL;
static jint maskCacheIndex = 0;
static id<MTLRenderCommandEncoder> encoder = NULL;

#define MTLVC_ADD_VERTEX(TX, TY, DX, DY, DZ) \
    do { \
        J2DVertex *v = &vertexCache[vertexCacheIndex++]; \
        v->txtpos[0] = TX; \
        v->txtpos[1] = TY; \
        v->position[0]= DX; \
        v->position[1] = DY; \
    } while (0)

#define MTLVC_ADD_TRIANGLES(TX1, TY1, TX2, TY2, DX1, DY1, DX2, DY2) \
    do { \
        MTLVC_ADD_VERTEX(TX1, TY1, DX1, DY1, 0); \
        MTLVC_ADD_VERTEX(TX2, TY1, DX2, DY1, 0); \
        MTLVC_ADD_VERTEX(TX2, TY2, DX2, DY2, 0); \
        MTLVC_ADD_VERTEX(TX2, TY2, DX2, DY2, 0); \
        MTLVC_ADD_VERTEX(TX1, TY2, DX1, DY2, 0); \
        MTLVC_ADD_VERTEX(TX1, TY1, DX1, DY1, 0); \
    } while (0)

// Next define should exactly match to the amount
// of MTLVC_ADD_VERTEX in MTLVC_ADD_TRIANGLES
#define VERTS_FOR_A_QUAD 6

jboolean
MTLVertexCache_InitVertexCache()
{
    J2dTraceLn(J2D_TRACE_INFO, "MTLVertexCache_InitVertexCache");

    if (vertexCache == NULL) {
        J2dTraceLn(J2D_TRACE_INFO, "MTLVertexCache_InitVertexCache : vertexCache == NULL");
        vertexCache = (J2DVertex *)malloc(MTLVC_MAX_INDEX * sizeof(J2DVertex));
        if (vertexCache == NULL) {
            return JNI_FALSE;
        }
    }

    return JNI_TRUE;
}

void
MTLVertexCache_FlushVertexCache(MTLContext *mtlc)
{
    J2dTraceLn(J2D_TRACE_INFO, "MTLVertexCache_FlushVertexCache");

    if (vertexCacheIndex > 0) {
        [encoder setVertexBytes: vertexCache length:vertexCacheIndex * sizeof(J2DVertex)
                                                atIndex:MeshVertexBuffer];

        [encoder setFragmentTexture:maskCacheTex.texture atIndex: 0];
        J2dTraceLn1(J2D_TRACE_INFO,
            "MTLVertexCache_FlushVertexCache : encode %d characters", (vertexCacheIndex / 6));
        [encoder drawPrimitives:MTLPrimitiveTypeTriangle vertexStart:0 vertexCount:vertexCacheIndex];
    }
    vertexCacheIndex = 0;
    maskCacheIndex = 0;

    if (maskCacheTex != nil) {
        [[mtlc getCommandBufferWrapper] registerPooledTexture:maskCacheTex];
        [maskCacheTex release];
        maskCacheTex = nil;
    }
}

void
MTLVertexCache_FlushGlyphVertexCache()
{
    J2dTraceLn(J2D_TRACE_INFO, "MTLVertexCache_FlushGlyphVertexCache");

    if (vertexCacheIndex > 0) {
        [encoder setVertexBytes: vertexCache length:vertexCacheIndex * sizeof(J2DVertex)
                                                atIndex:MeshVertexBuffer];
        id<MTLTexture> glyphCacheTex = MTLTR_GetGlyphCacheTexture();
        [encoder setFragmentTexture:glyphCacheTex atIndex: 0];
        J2dTraceLn1(J2D_TRACE_INFO,
            "MTLVertexCache_FlushGlyphVertexCache : encode %d characters", (vertexCacheIndex / 6));
        [encoder drawPrimitives:MTLPrimitiveTypeTriangle vertexStart:0 vertexCount:vertexCacheIndex];
    }
    vertexCacheIndex = 0;
}

void MTLVertexCache_FreeVertexCache()
{
    free(vertexCache);
    vertexCache = NULL;
}

static jboolean
MTLVertexCache_InitMaskCache(MTLContext *mtlc) {
    J2dTraceLn(J2D_TRACE_INFO, "MTLVertexCache_InitMaskCache");
    if (maskCacheTex == NULL) {
        maskCacheTex = [mtlc.texturePool getTexture:MTLVC_MASK_CACHE_WIDTH_IN_TEXELS
                                             height:MTLVC_MASK_CACHE_HEIGHT_IN_TEXELS
                                             format:MTLPixelFormatA8Unorm];
        [maskCacheTex retain];
        if (maskCacheTex == nil) {
            J2dTraceLn(J2D_TRACE_ERROR, "MTLVertexCache_InitMaskCache: can't obtain temporary texture object from pool");
            return JNI_FALSE;
        }
    }
    // init special fully opaque tile in the upper-right corner of
    // the mask cache texture

    char tile[MTLVC_MASK_CACHE_TILE_SIZE];
    memset(tile, 0xff, MTLVC_MASK_CACHE_TILE_SIZE);

    jint texx = MTLVC_MASK_CACHE_TILE_WIDTH * (MTLVC_MASK_CACHE_WIDTH_IN_TILES - 1);

    jint texy = MTLVC_MASK_CACHE_TILE_HEIGHT * (MTLVC_MASK_CACHE_HEIGHT_IN_TILES - 1);

    NSUInteger bytesPerRow = 1 * MTLVC_MASK_CACHE_TILE_WIDTH;

    MTLRegion region = {
            {texx,  texy,   0},
            {MTLVC_MASK_CACHE_TILE_WIDTH, MTLVC_MASK_CACHE_TILE_HEIGHT, 1}
    };


    // do we really need this??
    [maskCacheTex.texture replaceRegion:region
                    mipmapLevel:0
                      withBytes:tile
                    bytesPerRow:bytesPerRow];

    return JNI_TRUE;
}

void
MTLVertexCache_EnableMaskCache(MTLContext *mtlc, BMTLSDOps *dstOps)
{
    J2dTraceLn(J2D_TRACE_INFO, "MTLVertexCache_EnableMaskCache");

    if (!MTLVertexCache_InitVertexCache()) {
        return;
    }

    if (maskCacheTex == NULL) {
        if (!MTLVertexCache_InitMaskCache(mtlc)) {
            return;
        }
    }
    MTLVertexCache_CreateSamplingEncoder(mtlc, dstOps);
}

void
MTLVertexCache_DisableMaskCache(MTLContext *mtlc)
{
    // TODO : Once we enable check_previous_op
    // we will start using DisableMaskCache until then
    // we are force flushing vertexcache.
    J2dTraceLn(J2D_TRACE_INFO, "MTLVertexCache_DisableMaskCache");
    MTLVertexCache_FlushVertexCache(mtlc);
    maskCacheIndex = 0;
    free(vertexCache);
    vertexCache = NULL;
}

void
MTLVertexCache_CreateSamplingEncoder(MTLContext *mtlc, BMTLSDOps *dstOps) {
    J2dTraceLn(J2D_TRACE_INFO, "MTLVertexCache_CreateSamplingEncoder");
    encoder = [mtlc.encoderManager getTextEncoder:dstOps
                                         isSrcOpaque:NO];
}

void
MTLVertexCache_AddMaskQuad(MTLContext *mtlc,
                           jint srcx, jint srcy,
                           jint dstx, jint dsty,
                           jint width, jint height,
                           jint maskscan, void *mask,
                           BMTLSDOps *dstOps)
{
    jfloat tx1, ty1, tx2, ty2;
    jfloat dx1, dy1, dx2, dy2;

    J2dTraceLn1(J2D_TRACE_INFO, "MTLVertexCache_AddMaskQuad: %d",
                maskCacheIndex);

    // MTLVC_ADD_TRIANGLES at the end of this function
    // will place VERTS_FOR_A_QUAD vertexes to the vertex cache
    // check free space and flush if needed.
    if ((maskCacheIndex >= MTLVC_MASK_CACHE_MAX_INDEX) ||
         ((vertexCacheIndex + VERTS_FOR_A_QUAD) >= MTLVC_MAX_INDEX))
    {
        J2dTraceLn2(J2D_TRACE_INFO, "maskCacheIndex = %d, vertexCacheIndex = %d", maskCacheIndex, vertexCacheIndex);
        MTLVertexCache_FlushVertexCache(mtlc);
        MTLVertexCache_EnableMaskCache(mtlc, dstOps);
        maskCacheIndex = 0;
    }

    if (mask != NULL) {
        jint texx = MTLVC_MASK_CACHE_TILE_WIDTH *
                    (maskCacheIndex % MTLVC_MASK_CACHE_WIDTH_IN_TILES);
        jint texy = MTLVC_MASK_CACHE_TILE_HEIGHT *
                    (maskCacheIndex / MTLVC_MASK_CACHE_WIDTH_IN_TILES);
        J2dTraceLn5(J2D_TRACE_INFO, "texx = %d texy = %d width = %d height = %d maskscan = %d", texx, texy, width,
                    height, maskscan);
        NSUInteger bytesPerRow = 1 * width;
        NSUInteger slice = bytesPerRow * srcy + srcx;
        MTLRegion region = {
                {texx,  texy,   0},
                {width, height, 1}
        };

        // Whenever we have source stride bigger that destination stride
        // we need to pick appropriate source subtexture. In repalceRegion
        // we can give destination subtexturing properly but we can't
        // subtexture from system memory glyph we have. So in such
        // cases we are creating seperate tile and scan the source
        // stride into destination using memcpy. In case of OpenGL we
        // can update source pointers, in case of D3D we ar doing memcpy.
        // We can use MTLBuffer and then copy source subtexture but that
        // adds extra blitting logic.
        // TODO : Research more and try removing memcpy logic.
        if (maskscan <= width) {
            int height_offset = bytesPerRow * srcy;
            [maskCacheTex.texture replaceRegion:region
                            mipmapLevel:0
                              withBytes:mask + height_offset
                            bytesPerRow:bytesPerRow];
        } else {
            int dst_offset, src_offset;
            int size = 1 * width * height;
            char tile[size];
            dst_offset = 0;
            for (int i = srcy; i < srcy + height; i++) {
                J2dTraceLn2(J2D_TRACE_INFO, "srcx = %d srcy = %d", srcx, srcy);
                src_offset = maskscan * i + srcx;
                J2dTraceLn2(J2D_TRACE_INFO, "src_offset = %d dst_offset = %d", src_offset, dst_offset);
                memcpy(tile + dst_offset, mask + src_offset, width);
                dst_offset = dst_offset + width;
            }
            [maskCacheTex.texture replaceRegion:region
                            mipmapLevel:0
                              withBytes:tile
                            bytesPerRow:bytesPerRow];
        }

        tx1 = ((jfloat) texx) / MTLVC_MASK_CACHE_WIDTH_IN_TEXELS;
        ty1 = ((jfloat) texy) / MTLVC_MASK_CACHE_HEIGHT_IN_TEXELS;
    } else {
        tx1 = ((jfloat)MTLVC_MASK_CACHE_SPECIAL_TILE_X) /
              MTLVC_MASK_CACHE_WIDTH_IN_TEXELS;
        ty1 = ((jfloat)MTLVC_MASK_CACHE_SPECIAL_TILE_Y) /
              MTLVC_MASK_CACHE_HEIGHT_IN_TEXELS;
    }
    maskCacheIndex++;

    tx2 = tx1 + (((jfloat)width) / MTLVC_MASK_CACHE_WIDTH_IN_TEXELS);
    ty2 = ty1 + (((jfloat)height) / MTLVC_MASK_CACHE_HEIGHT_IN_TEXELS);

    dx1 = (jfloat)dstx;
    dy1 = (jfloat)dsty;
    dx2 = dx1 + width;
    dy2 = dy1 + height;

    J2dTraceLn8(J2D_TRACE_INFO, "tx1 = %f ty1 = %f tx2 = %f ty2 = %f dx1 = %f dy1 = %f dx2 = %f dy2 = %f", tx1, ty1, tx2, ty2, dx1, dy1, dx2, dy2);
    MTLVC_ADD_TRIANGLES(tx1, ty1, tx2, ty2,
                        dx1, dy1, dx2, dy2);
}

void
MTLVertexCache_AddGlyphQuad(MTLContext *mtlc,
                            jfloat tx1, jfloat ty1, jfloat tx2, jfloat ty2,
                            jfloat dx1, jfloat dy1, jfloat dx2, jfloat dy2)
{
    J2dTraceLn(J2D_TRACE_INFO, "MTLVertexCache_AddGlyphQuad");

    // MTLVC_ADD_TRIANGLES adds VERTS_FOR_A_QUAD vertexes into Cache
    // so need to check space for VERTS_FOR_A_QUAD elements
    if ((vertexCacheIndex + VERTS_FOR_A_QUAD) >= MTLVC_MAX_INDEX)
    {
        J2dTraceLn2(J2D_TRACE_INFO, "maskCacheIndex = %d, vertexCacheIndex = %d", maskCacheIndex, vertexCacheIndex);
        MTLVertexCache_FlushGlyphVertexCache();
    }

    MTLVC_ADD_TRIANGLES(tx1, ty1, tx2, ty2,
                        dx1, dy1, dx2, dy2);
}
