/*
 * Copyright 2020 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "include/core/SkExecutor.h"
#include "include/core/SkFont.h"
#include "include/core/SkFontStyle.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPoint.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkScalar.h"
#include "include/core/SkSurfaceProps.h"
#include "include/core/SkTypeface.h"
#include "include/core/SkTypes.h"
#include "include/private/base/SkTo.h"
#include "src/base/SkZip.h"
#include "src/core/SkEnumerate.h"
#include "src/core/SkGlyph.h"
#include "src/core/SkGlyphBuffer.h"
#include "src/core/SkScalerContext.h"
#include "src/core/SkStrike.h"
#include "src/core/SkStrikeCache.h"
#include "src/core/SkStrikeSpec.h"
#include "src/core/SkTaskGroup.h"
#include "src/text/StrikeForGPU.h"
#include "tests/Test.h"
#include "tools/ToolUtils.h"

#include <atomic>
#include <cstddef>
#include <functional>
#include <initializer_list>
#include <memory>

using namespace sktext;
using namespace skglyph;

class Barrier {
public:
    Barrier(int threadCount) : fThreadCount(threadCount) { }
    void waitForAll() {
        fThreadCount -= 1;
        while (fThreadCount > 0) { }
    }

private:
    std::atomic<int> fThreadCount;
};

// This should stay in sync with the implementation from SubRunContainer.
static SkRect prepare_for_mask_drawing(StrikeForGPU* strike,
                                       SkDrawableGlyphBuffer* accepted,
                                       SkSourceGlyphBuffer* rejected) {
    SkGlyphRect boundingRect = skglyph::empty_rect();
    StrikeMutationMonitor m{strike};
    for (auto [i, packedID, pos] : SkMakeEnumerate(accepted->input())) {
        if (SkScalarsAreFinite(pos.x(), pos.y())) {
            SkGlyphDigest digest = strike->digestFor(kDirectMask, packedID);
            if (!digest.isEmpty()) {
                if (digest.fitsInAtlasDirect()) {
                    const SkGlyphRect glyphBounds = digest.bounds().offset(pos);
                    boundingRect = skglyph::rect_union(boundingRect, glyphBounds);
                    accepted->accept(packedID, glyphBounds.leftTop(), digest.maskFormat());
                } else {
                    rejected->reject(i);
                }
            }
        }
    }

    return boundingRect.rect();
}

DEF_TEST(SkStrikeMultiThread, Reporter) {
    sk_sp<SkTypeface> typeface =
            ToolUtils::create_portable_typeface("serif", SkFontStyle::Italic());
    static constexpr int kThreadCount = 4;

    Barrier barrier{kThreadCount};

    SkFont font;
    font.setEdging(SkFont::Edging::kAntiAlias);
    font.setSubpixel(true);
    font.setTypeface(typeface);

    SkGlyphID glyphs['z'];
    SkPoint pos['z'];
    for (int c = ' '; c < 'z'; c++) {
        glyphs[c] = font.unicharToGlyph(c);
        pos[c] = {30.0f * c + 30, 30.0f};
    }
    constexpr size_t glyphCount = 'z' - ' ';
    auto data = SkMakeZip(glyphs, pos).subspan(SkTo<int>(' '), glyphCount);

    SkPaint defaultPaint;
    SkStrikeSpec strikeSpec = SkStrikeSpec::MakeMask(
            font, defaultPaint, SkSurfaceProps(0, kUnknown_SkPixelGeometry),
            SkScalerContextFlags::kNone, SkMatrix::I());

    SkStrikeCache strikeCache;

    // Make our own executor so the --threads parameter doesn't mess things up.
    auto executor = SkExecutor::MakeFIFOThreadPool(kThreadCount);
    for (int tries = 0; tries < 100; tries++) {
        SkStrike strike{&strikeCache, strikeSpec, strikeSpec.createScalerContext(), nullptr,
                        nullptr};

        auto perThread = [&](int threadIndex) {
            barrier.waitForAll();

            auto local = data.subspan(threadIndex * 2, data.size() - kThreadCount * 2);
            for (int i = 0; i < 100; i++) {
                SkDrawableGlyphBuffer accepted;
                SkSourceGlyphBuffer rejected;

                accepted.ensureSize(glyphCount);
                rejected.setSource(local);

                accepted.startSource(rejected.source());
                prepare_for_mask_drawing(&strike, &accepted, &rejected);
                rejected.flipRejectsToSource();
                accepted.reset();
            }
        };

        SkTaskGroup(*executor).batch(kThreadCount, perThread);
    }
}