#include "testHarness.h"

#include "vf/Block.h"
#include "vf/SaveIntegrity.h"
#include "vf/SaveMigration.h"

#include <cstdint>
#include <string>
#include <vector>

using namespace vf;

namespace {

Chunk texturedChunk(int seed) {
    Chunk chunk;
    for (int x = 0; x < chunkSize; ++x)
        for (int y = 0; y < chunkSize; ++y)
            for (int z = 0; z < chunkSize; ++z) {
                int value = 1 + (x * 7 + y * 5 + z * 3 + seed) % 12;
                chunk.set(x, y, z, static_cast<Block>(value));
            }
    return chunk;
}

Chunk uniformChunk(Block block) {
    Chunk chunk;
    for (int x = 0; x < chunkSize; ++x)
        for (int y = 0; y < chunkSize; ++y)
            for (int z = 0; z < chunkSize; ++z) chunk.set(x, y, z, block);
    return chunk;
}

SaveChunkRecord buildRecord(const Vec3i& coord, const Chunk& blocks, SaveVersion version) {
    SaveChunkRecord record;
    record.coord = coord;
    record.blocks = blocks;
    if (versionHasLight(version)) record.light = defaultChunkLight(blocks, saveDefaultSkyLight);
    return record;
}

SaveContainer buildContainer(SaveVersion version, int chunkTotal) {
    SaveContainer container;
    container.version = version;
    for (int i = 0; i < chunkTotal; ++i)
        container.chunks.push_back(
            buildRecord(Vec3i{i, 0, i * 2}, texturedChunk(i), version));
    return container;
}

struct EntrySlot {
    std::size_t entryAt = 0;
    std::size_t payloadAt = 0;
    std::size_t payloadBytes = 0;
};

EntrySlot slotOf(const ByteBuffer& buffer, std::size_t index) {
    EntrySlot slot;
    SaveHeader header;
    if (!readSaveHeader(buffer.data(), buffer.size(), header)) return slot;
    std::vector<SaveTableEntry> entries;
    if (!readSaveTable(buffer.data(), buffer.size(), header, entries)) return slot;
    if (index >= entries.size()) return slot;
    slot.entryAt = saveHeaderBytes + index * saveEntryBytes;
    slot.payloadAt = static_cast<std::size_t>(entries[index].sectorOffset) * header.sectorBytes;
    slot.payloadBytes = entries[index].payloadBytes;
    return slot;
}

void refreshTableChecksum(ByteBuffer& buffer) {
    SaveHeader header;
    if (!readSaveHeader(buffer.data(), buffer.size(), header)) return;
    if (!versionHasChecksum(static_cast<SaveVersion>(header.version))) return;
    uint32_t checksum = fnv1a32(buffer.data() + saveHeaderBytes, saveTableBytes(header));
    saveWriteU32At(buffer.data(), buffer.size(), 24, checksum);
}

bool sameBlocks(const Chunk& a, const Chunk& b) {
    for (std::size_t i = 0; i < a.raw().size(); ++i)
        if (a.raw()[i] != b.raw()[i]) return false;
    return true;
}

} // namespace

VF_TEST(scannerFindsNothingWrongWithAFreshContainer) {
    SaveContainer container = buildContainer(SaveVersion::V4, 4);
    ByteBuffer buffer = writeSaveContainer(container);

    SaveScanner scanner;
    IntegrityReport report = scanner.scan(buffer);
    CHECK(report.clean());
    CHECK(report.headerReadable);
    CHECK(!report.fatal());
    CHECK(!report.repairable());
    CHECK(report.version == SaveVersion::V4);
    CHECK_EQ(report.declaredChunks, static_cast<std::size_t>(4));
    CHECK_EQ(report.tableEntries, static_cast<std::size_t>(4));
    CHECK_EQ(report.readableChunks, static_cast<std::size_t>(4));
    CHECK_EQ(report.bufferBytes, buffer.size());
}

VF_TEST(aBufferTooShortForAHeaderIsFatal) {
    ByteBuffer stump(11, 0);
    SaveScanner scanner;
    IntegrityReport report = scanner.scan(stump);
    CHECK_EQ(report.issues.size(), static_cast<std::size_t>(1));
    CHECK(report.issues[0].kind == IntegrityIssueKind::TruncatedBuffer);
    CHECK(report.issues[0].severity == IssueSeverity::Fatal);
    CHECK(!report.headerReadable);
    CHECK(report.fatal());
}

VF_TEST(aWrongMagicIsFatalAtTheStartOfTheBuffer) {
    ByteBuffer buffer = writeSaveContainer(buildContainer(SaveVersion::V4, 2));
    saveWriteU32At(buffer.data(), buffer.size(), 0, 0x4E4F5045u);

    SaveScanner scanner;
    IntegrityReport report = scanner.scan(buffer);
    CHECK_EQ(report.issues.size(), static_cast<std::size_t>(1));
    CHECK(report.issues[0].kind == IntegrityIssueKind::BadMagic);
    CHECK(report.issues[0].severity == IssueSeverity::Fatal);
    CHECK_EQ(report.issues[0].byteOffset, static_cast<std::size_t>(0));
    CHECK(!report.headerReadable);
}

VF_TEST(anUnknownFormatVersionIsFatalAtTheVersionField) {
    ByteBuffer buffer = writeSaveContainer(buildContainer(SaveVersion::V4, 2));
    saveWriteU32At(buffer.data(), buffer.size(), 4, 9u);

    SaveScanner scanner;
    IntegrityReport report = scanner.scan(buffer);
    CHECK_EQ(report.issues.size(), static_cast<std::size_t>(1));
    CHECK(report.issues[0].kind == IntegrityIssueKind::UnknownVersion);
    CHECK(report.issues[0].severity == IssueSeverity::Fatal);
    CHECK_EQ(report.issues[0].byteOffset, static_cast<std::size_t>(4));
    CHECK(report.issues[0].detail.find("v1..v4") != std::string::npos);
}

VF_TEST(aStaleRecordChecksumIsRecoverableAtTheEndOfTheRecord) {
    ByteBuffer buffer = writeSaveContainer(buildContainer(SaveVersion::V4, 3));
    EntrySlot slot = slotOf(buffer, 1);
    std::size_t checksumAt = slot.payloadAt + slot.payloadBytes - 4;
    buffer[checksumAt] = static_cast<uint8_t>(buffer[checksumAt] ^ 0x01u);

    SaveScanner scanner;
    IntegrityReport report = scanner.scan(buffer);
    CHECK_EQ(report.issues.size(), static_cast<std::size_t>(1));
    CHECK(report.issues[0].kind == IntegrityIssueKind::ChecksumMismatch);
    CHECK(report.issues[0].severity == IssueSeverity::Recoverable);
    CHECK_EQ(report.issues[0].byteOffset, checksumAt);
    CHECK_EQ(report.issues[0].entryIndex, 1);
    CHECK(report.issues[0].hasChunkCoord);
    CHECK(report.repairable());
}