#include "rive/core/binary_reader.hpp"
#include "rive/core/reader.h"
#include "rive/span.hpp"
#include <vector>

using namespace rive;

BinaryReader::BinaryReader(Span<const uint8_t> span) : BinaryReader(span.begin(), span.size()) {}

BinaryReader::BinaryReader(const uint8_t* bytes, size_t length) :
    m_Position(bytes), m_End(bytes + length), m_Overflowed(false), m_Length(length) {}

bool BinaryReader::reachedEnd() const { return m_Position == m_End || didOverflow(); }

size_t BinaryReader::lengthInBytes() const { return m_Length; }

bool BinaryReader::didOverflow() const { return m_Overflowed; }

void BinaryReader::overflow() {
    m_Overflowed = true;
    m_Position = m_End;
}

uint64_t BinaryReader::readVarUint64() {
    uint64_t value;
    auto readBytes = decode_uint_leb(m_Position, m_End, &value);
    if (readBytes == 0) {
        overflow();
        return 0;
    }
    m_Position += readBytes;
    return value;
}

std::string BinaryReader::readString() {
    uint64_t length = readVarUint64();
    if (didOverflow()) {
        return std::string();
    }

    std::vector<char> rawValue(length + 1);
    auto readBytes = decode_string(length, m_Position, m_End, &rawValue[0]);
    if (readBytes != length) {
        overflow();
        return std::string();
    }
    m_Position += readBytes;
    return std::string(rawValue.data(), length);
}

Span<const uint8_t> BinaryReader::readBytes() {
    uint64_t length = readVarUint64();
    if (didOverflow()) {
        return Span<const uint8_t>(m_Position, 0);
    }

    const uint8_t* start = m_Position;
    m_Position += length;
    return {start, (size_t)length};
}

double BinaryReader::readFloat64() {
    double value;
    auto readBytes = decode_double(m_Position, m_End, &value);
    if (readBytes == 0) {
        overflow();
        return 0.0;
    }
    m_Position += readBytes;
    return value;
}

float BinaryReader::readFloat32() {
    float value;
    auto readBytes = decode_float(m_Position, m_End, &value);
    if (readBytes == 0) {
        overflow();
        return 0.0f;
    }
    m_Position += readBytes;
    return value;
}

uint8_t BinaryReader::readByte() {
    if (m_End - m_Position < 1) {
        overflow();
        return 0;
    }
    return *m_Position++;
}

uint32_t BinaryReader::readUint32() {
    uint32_t value;
    auto readBytes = decode_uint_32(m_Position, m_End, &value);
    if (readBytes == 0) {
        overflow();
        return 0;
    }
    m_Position += readBytes;
    return value;
}