/*
 * Copyright (c) 2021, Jan de Visser <jan@de-visser.net>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <cstring>

#include <AK/String.h>
#include <AK/StringBuilder.h>
#include <LibSQL/Serialize.h>
#include <LibSQL/Tuple.h>
#include <LibSQL/TupleDescriptor.h>
#include <LibSQL/Value.h>

namespace SQL {

Tuple::Tuple()
    : m_descriptor()
    , m_data()
{
}

Tuple::Tuple(TupleDescriptor const& descriptor, u32 pointer)
    : m_descriptor(descriptor)
    , m_data()
    , m_pointer(pointer)
{
    for (auto& element : descriptor) {
        m_data.append(Value(element.type));
    }
}

Tuple::Tuple(TupleDescriptor const& descriptor, ByteBuffer& buffer, size_t& offset)
    : Tuple(descriptor)
{
    deserialize(buffer, offset);
}

Tuple::Tuple(TupleDescriptor const& descriptor, ByteBuffer& buffer)
    : Tuple(descriptor)
{
    size_t offset = 0;
    deserialize(buffer, offset);
}

void Tuple::deserialize(ByteBuffer& buffer, size_t& offset)
{
    dbgln_if(SQL_DEBUG, "deserialize tuple at offset {}", offset);
    deserialize_from<u32>(buffer, offset, m_pointer);
    dbgln_if(SQL_DEBUG, "pointer: {}", m_pointer);
    m_data.clear();
    for (auto& part : m_descriptor) {
        m_data.append(Value(part.type, buffer, offset));
        dbgln_if(SQL_DEBUG, "Deserialized element {} = {}", part.name, m_data.last().to_string().value());
    }
}

void Tuple::serialize(ByteBuffer& buffer) const
{
    VERIFY(m_descriptor.size() == m_data.size());
    dbgln_if(SQL_DEBUG, "Serializing tuple pointer {}", pointer());
    serialize_to<u32>(buffer, pointer());
    for (auto ix = 0u; ix < m_descriptor.size(); ix++) {
        auto& key_part = m_data[ix];
        if constexpr (SQL_DEBUG) {
            auto str_opt = key_part.to_string();
            auto& key_part_definition = m_descriptor[ix];
            dbgln("Serialized part {} = {}", key_part_definition.name, (str_opt.has_value()) ? str_opt.value() : "(null)");
        }
        key_part.serialize(buffer);
    }
}

Tuple::Tuple(Tuple const& other)
    : m_descriptor()
    , m_data()
{
    copy_from(other);
}

Tuple& Tuple::operator=(Tuple const& other)
{
    if (this != &other) {
        copy_from(other);
    }
    return *this;
}

Optional<size_t> Tuple::index_of(String name) const
{
    auto n = move(name);
    for (auto ix = 0u; ix < m_descriptor.size(); ix++) {
        auto& part = m_descriptor[ix];
        if (part.name == n) {
            return (int)ix;
        }
    }
    return {};
}

Value const& Tuple::operator[](size_t ix) const
{
    VERIFY(ix < m_data.size());
    return m_data[ix];
}

Value& Tuple::operator[](size_t ix)
{
    VERIFY(ix < m_data.size());
    return m_data[ix];
}

Value const& Tuple::operator[](String const& name) const
{
    auto index = index_of(name);
    VERIFY(index.has_value());
    return (*this)[index.value()];
}

Value& Tuple::operator[](String const& name)
{
    auto index = index_of(name);
    VERIFY(index.has_value());
    return (*this)[index.value()];
}

void Tuple::append(const Value& value)
{
    VERIFY(m_descriptor.size() == 0);
    m_data.append(value);
}

Tuple& Tuple::operator+=(Value const& value)
{
    append(value);
    return *this;
}

bool Tuple::is_compatible(Tuple const& other) const
{
    if ((m_descriptor.size() == 0) && (other.m_descriptor.size() == 0)) {
        return true;
    }
    if (m_descriptor.size() != other.m_descriptor.size()) {
        return false;
    }
    for (auto ix = 0u; ix < m_descriptor.size(); ix++) {
        auto& my_part = m_descriptor[ix];
        auto& other_part = other.m_descriptor[ix];
        if (my_part.type != other_part.type) {
            return false;
        }
        if (my_part.order != other_part.order) {
            return false;
        }
    }
    return true;
}

String Tuple::to_string() const
{
    StringBuilder builder;
    for (auto& part : m_data) {
        if (!builder.is_empty()) {
            builder.append('|');
        }
        auto str_opt = part.to_string();
        builder.append((str_opt.has_value()) ? str_opt.value() : "(null)");
    }
    if (pointer() != 0) {
        builder.appendff(":{}", pointer());
    }
    return builder.build();
}

size_t Tuple::size() const
{
    size_t sz = sizeof(u32);
    for (auto& part : m_data) {
        sz += part.size();
    }
    return sz;
}

void Tuple::copy_from(const Tuple& other)
{
    m_descriptor.clear();
    for (TupleElement const& part : other.m_descriptor) {
        m_descriptor.append(part);
    }
    m_data.clear();
    for (auto& part : other.m_data) {
        m_data.append(part);
    }
    m_pointer = other.pointer();
}

int Tuple::compare(const Tuple& other) const
{
    auto num_values = min(m_data.size(), other.m_data.size());
    VERIFY(num_values > 0);
    for (auto ix = 0u; ix < num_values; ix++) {
        auto ret = m_data[ix].compare(other.m_data[ix]);
        if (ret != 0) {
            if ((ix < m_descriptor.size()) && m_descriptor[ix].order == Order::Descending)
                ret = -ret;
            return ret;
        }
    }
    return 0;
}

int Tuple::match(const Tuple& other) const
{
    auto other_index = 0u;
    for (auto& part : other.descriptor()) {
        auto other_value = other[other_index];
        if (other_value.is_null())
            return 0;
        auto my_index = index_of(part.name);
        if (!my_index.has_value())
            return -1;
        auto ret = m_data[my_index.value()].compare(other_value);
        if (ret != 0)
            return (m_descriptor[my_index.value()].order == Order::Descending) ? -ret : ret;
        other_index++;
    }
    return 0;
}

u32 Tuple::hash() const
{
    u32 ret = 0u;
    for (auto& value : m_data) {
        // This is an extension of the pair_int_hash function from AK/HashFunctions.h:
        if (!ret)
            ret = value.hash();
        else
            ret = int_hash((ret * 209) ^ (value.hash() * 413));
    }
    return ret;
}

}