#include "testHarness.h"
#include "vf/Codec.h"
#include "vf/EditHistory.h"
#include "vf/Schematic.h"
#include "vf/Selection.h"

#include <string>
#include <vector>

using namespace vf;

namespace {

// Byte offsets into an encoded schematic. The frame is magic, version, body
// length, body, checksum - all big-endian, all fixed width, which is what lets
// these tests damage one field at a time.
constexpr std::size_t bodyOffset = 12;
constexpr std::size_t paletteOffsetInBody = 26;

uint32_t readU32(const ByteBuffer& bytes, std::size_t at) {
    return (static_cast<uint32_t>(bytes[at]) << 24) | (static_cast<uint32_t>(bytes[at + 1]) << 16) |
           (static_cast<uint32_t>(bytes[at + 2]) << 8) | static_cast<uint32_t>(bytes[at + 3]);
}

void writeU32(ByteBuffer& bytes, std::size_t at, uint32_t value) {
    bytes[at] = static_cast<uint8_t>(value >> 24);
    bytes[at + 1] = static_cast<uint8_t>(value >> 16);
    bytes[at + 2] = static_cast<uint8_t>(value >> 8);
    bytes[at + 3] = static_cast<uint8_t>(value);
}

void refreshChecksum(ByteBuffer& bytes) {
    uint32_t bodyLength = readU32(bytes, 8);
    writeU32(bytes, bodyOffset + bodyLength, fnv1a32(bytes.data() + bodyOffset, bodyLength));
}

// Rewrites one body byte and repairs the checksum, so the decoder has to reject
// the buffer on its own merits rather than on a broken hash.
void patchBody(ByteBuffer& bytes, std::size_t offsetInBody, uint8_t value) {
    bytes[bodyOffset + offsetInBody] = value;
    refreshChecksum(bytes);
}

World terrainWorld(int spanX, int spanZ) {
    World world;
    for (int z = 0; z < spanZ; ++z)
        for (int x = 0; x < spanX; ++x) {
            int height = 2 + ((x * 3 + z * 5) % 3);
            for (int y = 0; y <= height; ++y) {
                Block block = Block::Stone;
                if (y == height) block = Block::Grass;
                else if (y > height - 2) block = Block::Dirt;
                world.setBlock(x, y, z, block);
            }
        }
    return world;
}

bool sameRegion(const World& left, const World& right, const Vec3i& lo, const Vec3i& hi) {
    for (int y = lo.y; y <= hi.y; ++y)
        for (int z = lo.z; z <= hi.z; ++z)
            for (int x = lo.x; x <= hi.x; ++x)
                if (left.blockAt(x, y, z) != right.blockAt(x, y, z)) return false;
    return true;
}

Schematic decodedCopy(const ByteBuffer& bytes, SchematicError& error) {
    Schematic loaded;
    error = Schematic::decode(bytes.data(), bytes.size(), loaded);
    return loaded;
}

} // namespace

VF_TEST(aSchematicRoundTripRebuildsTheExactSameBlocks) {
    World source = terrainWorld(9, 9);
    Selection region = Selection::box({0, 0, 0}, {8, 5, 8});
    Schematic saved = Schematic::capture(source, region, "ridge", "foksiu", 900u);

    CHECK(saved.header().dims == Vec3i(9, 6, 9));
    CHECK_EQ(saved.buffer().filledCount(), 9u * 6u * 9u);

    ByteBuffer bytes = saved.encode();
    SchematicError error = SchematicError::BadMagic;
    Schematic loaded = decodedCopy(bytes, error);
    CHECK(error == SchematicError::None);
    CHECK(loaded.buffer().sameContent(saved.buffer()));

    World rebuilt;
    std::size_t written = loaded.pasteInto(rebuilt, {0, 0, 0}, ClipboardBuffer::PasteMode::Overwrite);
    CHECK(written > 0u);
    CHECK(sameRegion(source, rebuilt, {0, 0, 0}, {8, 5, 8}));
}

VF_TEST(aSchematicCarriesItsMetadataThroughTheRoundTrip) {
    World source = terrainWorld(4, 4);
    Schematic saved = Schematic::capture(source, Selection::box({0, 0, 0}, {3, 3, 3}), "watchtower",
                                         "vulpes", 1234567890123ull);
    saved.setAnchor({1, 2, 3});

    ByteBuffer bytes = saved.encode();
    SchematicError error = SchematicError::BadMagic;
    Schematic loaded = decodedCopy(bytes, error);
    CHECK(error == SchematicError::None);
    CHECK(loaded.header().name == std::string("watchtower"));
    CHECK(loaded.header().author == std::string("vulpes"));
    CHECK_EQ(loaded.header().tick, 1234567890123ull);
    CHECK(loaded.header().anchor == Vec3i(1, 2, 3));
    CHECK(loaded.header().version == SchematicVersion::V2);
    CHECK(!loaded.migratedFromV1());
}

VF_TEST(theIndexWidthShrinksWithTheNumberOfDistinctBlocks) {
    CHECK_EQ(Schematic::bitsForPalette(1u), 1u);
    CHECK_EQ(Schematic::bitsForPalette(2u), 1u);
    CHECK_EQ(Schematic::bitsForPalette(3u), 2u);
    CHECK_EQ(Schematic::bitsForPalette(4u), 2u);
    CHECK_EQ(Schematic::bitsForPalette(5u), 4u);
    CHECK_EQ(Schematic::bitsForPalette(16u), 4u);
    CHECK_EQ(Schematic::bitsForPalette(17u), 8u);

    ClipboardBuffer twoTone({8, 8, 8}, {0, 0, 0});
    for (int y = 0; y < 8; ++y)
        for (int z = 0; z < 8; ++z)
            for (int x = 0; x < 8; ++x) twoTone.put(x, y, z, Block::Stone);
    Schematic plain = Schematic::fromBuffer(twoTone, "plain", "foksiu", 1u);
    CHECK_EQ(plain.header().paletteSize, 2u);
    CHECK_EQ(plain.header().indexBits, 1u);

    ClipboardBuffer manyTone = twoTone;
    for (int i = 0; i < 20; ++i) manyTone.put(i % 8, i / 8, 0, static_cast<Block>(20 + i));
    Schematic mixed = Schematic::fromBuffer(manyTone, "mixed", "foksiu", 1u);
    CHECK_EQ(mixed.header().paletteSize, 22u);
    CHECK_EQ(mixed.header().indexBits, 8u);

    SchematicError error = SchematicError::BadMagic;
    Schematic reloaded = decodedCopy(mixed.encode(), error);
    CHECK(error == SchematicError::None);
    CHECK(reloaded.buffer().sameContent(manyTone));
    CHECK_EQ(reloaded.header().indexBits, 8u);
}

VF_TEST(rotatingFourTimesByNinetyDegreesReturnsTheOriginal) {
    World source = terrainWorld(7, 5);
    Schematic original = Schematic::capture(source, Selection::box({0, 0, 0}, {6, 3, 4}), "spin",
                                            "foksiu", 10u);
    original.setAnchor({2, 1, 3});

    Schematic turning = original;
    for (int step = 0; step < 4; ++step) turning.rotate(Rotation::Cw90);
    CHECK(turning.buffer().sameContent(original.buffer()));
    CHECK(turning.header().dims == original.header().dims);
    CHECK(turning.header().anchor == original.header().anchor);

    Schematic half = original;
    half.rotate(Rotation::Cw180);
    Schematic twoQuarters = original;
    twoQuarters.rotate(Rotation::Cw90);
    twoQuarters.rotate(Rotation::Cw90);
    CHECK(half.buffer().sameContent(twoQuarters.buffer()));