/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

#include <config.h>

#include <test/lokassert.hpp>

#include <Delta.hpp>
#include <Util.hpp>
#include <Png.hpp>

/// Delta unit-tests.
class DeltaTests : public CPPUNIT_NS::TestFixture
{
    CPPUNIT_TEST_SUITE(DeltaTests);

#if ENABLE_DELTAS
    CPPUNIT_TEST(testDeltaSequence);
    CPPUNIT_TEST(testRandomDeltas);
#endif

    CPPUNIT_TEST_SUITE_END();

    void testDeltaSequence();
    void testRandomDeltas();

    std::vector<char> loadPng(const char *relpath,
                              png_uint_32& height,
                              png_uint_32& width,
                              png_uint_32& rowBytes)
    {
        std::ifstream file(relpath);
        std::stringstream buffer;
        buffer << file.rdbuf();
        file.close();
        std::vector<png_bytep> rows =
            Png::decodePNG(buffer, height, width, rowBytes);
        std::vector<char> output;
        for (png_uint_32 y = 0; y < height; ++y)
        {
            for (png_uint_32 i = 0; i < width * 4; ++i)
            {
                output.push_back(rows[y][i]);
            }
        }
        return output;
    }

    std::vector<char> applyDelta(
        const std::vector<char> &pixmap,
        png_uint_32 width, png_uint_32 height,
        const std::vector<char> &delta,
        const std::string& testname);

    void assertEqual(const std::vector<char> &a,
                     const std::vector<char> &b,
                     int width, int height,
                     const std::string& testname);
};

// Quick hack for debugging
std::vector<char> DeltaTests::applyDelta(
    const std::vector<char> &pixmap,
    png_uint_32 width, png_uint_32 height,
    const std::vector<char> &zDelta,
    const std::string& testname)
{
    LOK_ASSERT(zDelta.size() >= 4);
    LOK_ASSERT(zDelta[0] == 'D');

    std::vector<char> delta;
    delta.resize(1024*1024*4); // lots of extra space.

    size_t compSize = ZSTD_decompress( delta.data(), delta.size(),
                                       zDelta.data() + 1, zDelta.size() - 1);
    LOK_ASSERT_EQUAL(ZSTD_isError(compSize), (unsigned)false);

    delta.resize(compSize);

    // start with the same state.
    std::vector<char> output = pixmap;
    LOK_ASSERT_EQUAL(output.size(), size_t(pixmap.size()));
    LOK_ASSERT_EQUAL(output.size(), size_t(width * height * 4));

    size_t offset = 0, i;
    for (i = 0; i < delta.size() && offset < output.size();)
    {
        switch (delta[i])
        {
        case 'c': // copy row.
        {
            int count = (uint8_t)(delta[i+1]);
            int srcRow = (uint8_t)(delta[i+2]);
            int destRow = (uint8_t)(delta[i+3]);

//            std::cout << "copy " << count <<" row(s) " << srcRow << " to " << destRow << '\n';
            for (int cnt = 0; cnt < count; ++cnt)
            {
                const char *src = &pixmap[width * (srcRow + cnt) * 4];
                char *dest = &output[width * (destRow + cnt) * 4];
                for (size_t j = 0; j < width * 4; ++j)
                    *dest++ = *src++;
            }
            i += 4;
            break;
        }
        case 'd': // new run
        {
            int destRow = (uint8_t)(delta[i+1]);
            int destCol = (uint8_t)(delta[i+2]);
            size_t length = (uint8_t)(delta[i+3]);
            i += 4;

//            std::cout << "new " << length << " at " << destCol << ", " << destRow << '\n';
            LOK_ASSERT(length <= width - destCol);

            char *dest = &output[width * destRow * 4 + destCol * 4];
            for (size_t j = 0; j < length * 4 && i < delta.size(); ++j)
                *dest++ = delta[i++];
            break;
        }
        case 't': // termination
            LOK_ASSERT(i == delta.size() - 1);
            i++;
            break;
        default:
            std::cout << "Unknown delta code " << delta[i] << '\n';
            LOK_ASSERT(false);
            break;
        }
    }
    LOK_ASSERT_EQUAL(delta.size(), i);
    return output;
}

void DeltaTests::assertEqual(const std::vector<char> &a,
                             const std::vector<char> &b,
                             int width, int /* height */,
                             const std::string& testname)
{
    LOK_ASSERT_EQUAL(a.size(), b.size());
    for (size_t i = 0; i < a.size(); ++i)
    {
        if (a[i] != b[i])
        {
            std::cout << "Differences starting at byte " << i << ' '
                      << (i/4 % width) << ", " << (i / (width * 4)) << ":\n";
            size_t len;
            for (len = 0; (a[i+len] != b[i+len] || len < 8) && i + len < a.size(); ++len)
            {
                std::cout << std::hex << (int)((unsigned char)a[i+len]) << " != ";
                std::cout << std::hex << (int)((unsigned char)b[i+len]) << "  ";
                if (len > 0 && (len % 16 == 0))
                    std::cout<< '\n';
            }
            std::cout << " size " << len << '\n';
            LOK_ASSERT(false);
        }
    }
}

void DeltaTests::testDeltaSequence()
{
    constexpr auto testname = __func__;

    DeltaGenerator gen;

    png_uint_32 height, width, rowBytes;
    const TileWireId textWid = 1;
    std::vector<char> text =
        DeltaTests::loadPng(TDOC "/delta-text.png",
                            height, width, rowBytes);
    LOK_ASSERT(height == 256 && width == 256 && rowBytes == 256*4);
    LOK_ASSERT_EQUAL(size_t(256 * 256 * 4), text.size());

    const TileWireId text2Wid = 2;
    std::vector<char> text2 =
        DeltaTests::loadPng(TDOC "/delta-text2.png",
                            height, width, rowBytes);
    LOK_ASSERT(height == 256 && width == 256 && rowBytes == 256*4);
    LOK_ASSERT_EQUAL(size_t(256 * 256 * 4), text2.size());

    std::vector<char> delta;
    // Stash it in the cache
    LOK_ASSERT(gen.createDelta(
                       reinterpret_cast<unsigned char *>(&text[0]),
                       0, 0, width, height, width, height,
                       TileLocation(1, 2, 3, 0, 1), delta, textWid, false) == false);
    LOK_ASSERT(delta.size() == 0);

    // Build a delta between text2 & textWid
    LOK_ASSERT(gen.createDelta(
                       reinterpret_cast<unsigned char *>(&text2[0]),
                       0, 0, width, height, width, height,
                       TileLocation(1, 2, 3, 0, 1), delta, text2Wid, false) == true);
    LOK_ASSERT(delta.size() > 0);

    // Apply it to move to the second frame
    std::vector<char> reText2 = applyDelta(text, width, height, delta, testname);
    assertEqual(reText2, text2, width, height, testname);

    // Build a delta between text & text2Wid
    std::vector<char> two2one;
    LOK_ASSERT(gen.createDelta(
                       reinterpret_cast<unsigned char *>(&text[0]),
                       0, 0, width, height, width, height,
                       TileLocation(1, 2, 3, 0, 1), two2one, textWid, false) == true);
    LOK_ASSERT(two2one.size() > 0);

    // Apply it to get back to where we started
    std::vector<char> reText = applyDelta(text2, width, height, two2one, testname);
    assertEqual(reText, text, width, height, testname);
}

void DeltaTests::testRandomDeltas()
{
}

CPPUNIT_TEST_SUITE_REGISTRATION(DeltaTests);

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