#include "buffer.hh"

#include "buffer_manager.hh"
#include "window.hh"
#include "assert.hh"
#include "utils.hh"

#include <algorithm>

namespace Kakoune
{

template<typename T>
T clamp(T min, T max, T val)
{
    if (val < min)
        return min;
    if (val > max)
        return max;
    return val;
}

Buffer::Buffer(const std::string& name, Type type,
               const BufferString& initial_content)
    : m_name(name), m_type(type),
      m_history(1), m_history_cursor(m_history.begin()),
      m_content(initial_content), m_last_save_undo_group(m_history.begin())
{
    BufferManager::instance().register_buffer(this);

    compute_lines();
}

void Buffer::erase(const BufferIterator& begin, const BufferIterator& end)
{
    append_modification(BufferModification(BufferModification::Erase,
                                           begin, string(begin, end)));
    do_erase(begin, end);
}

void Buffer::insert(const BufferIterator& position, const BufferString& string)
{
    append_modification(BufferModification(BufferModification::Insert, position, string));
    do_insert(position, string);
}

void Buffer::do_erase(const BufferIterator& begin, const BufferIterator& end)
{
    m_content.erase(begin.m_position, end - begin);
    compute_lines();
}

void Buffer::do_insert(const BufferIterator& position, const BufferString& string)
{
    m_content.insert(position.m_position, string);
    compute_lines();
}

BufferIterator Buffer::iterator_at(const BufferCoord& line_and_column) const
{
    if (m_lines.empty())
        return begin();

    BufferPos line   = Kakoune::clamp<int>(0, m_lines.size() - 1, line_and_column.line);
    BufferPos column = Kakoune::clamp<int>(0, line_length(line),  line_and_column.column);
    return BufferIterator(*this, m_lines[line] + column);
}

BufferCoord Buffer::line_and_column_at(const BufferIterator& iterator) const
{
    BufferCoord result;
    if (not m_lines.empty())
    {
        result.line = line_at(iterator);
        result.column = iterator.m_position - m_lines[result.line];
    }
    return result;
}

BufferPos Buffer::line_at(const BufferIterator& iterator) const
{
    for (unsigned i = 0; i < m_lines.size(); ++i)
    {
        if (m_lines[i] > iterator.m_position)
            return i - 1;
    }
    return m_lines.size() - 1;
}

BufferSize Buffer::line_length(BufferPos line) const
{
    assert(not m_lines.empty());
    BufferPos end = (line >= m_lines.size() - 1) ?
                    m_content.size() : m_lines[line + 1] - 1;
    return end - m_lines[line];
}

BufferCoord Buffer::clamp(const BufferCoord& line_and_column) const
{
    if (m_lines.empty())
        return BufferCoord();

    BufferCoord result(line_and_column.line, line_and_column.column);
    result.line = Kakoune::clamp<int>(0, m_lines.size() - 1, result.line);
    result.column = Kakoune::clamp<int>(0, line_length(result.line), result.column);
    return result;
}

void Buffer::compute_lines()
{
    m_lines.clear();
    m_lines.push_back(0);
    for (BufferPos i = 0; i < m_content.size(); ++i)
    {
        if (m_content[i] == '\n')
            m_lines.push_back(i + 1);
    }
}

BufferIterator Buffer::begin() const
{
    return BufferIterator(*this, 0);
}

BufferIterator Buffer::end() const
{
    return BufferIterator(*this, length());
}

BufferSize Buffer::length() const
{
    return m_content.size();
}

BufferSize Buffer::line_count() const
{
    return m_lines.size();
}

BufferString Buffer::string(const BufferIterator& begin, const BufferIterator& end) const
{
    return m_content.substr(begin.m_position, end - begin);
}

BufferChar Buffer::at(BufferPos position) const
{
    return m_content[position];
}

void Buffer::begin_undo_group()
{
    assert(m_current_undo_group.empty());
    m_history.erase(m_history_cursor, m_history.end());
    m_history_cursor = m_history.end();
}

void Buffer::end_undo_group()
{
    m_history.push_back(m_current_undo_group);
    m_history_cursor = m_history.end();

    m_current_undo_group.clear();
}

BufferModification BufferModification::inverse() const
{
    Type inverse_type;
    switch (type)
    {
    case Insert: inverse_type = Erase;  break;
    case Erase:  inverse_type = Insert; break;
    default: assert(false);
    }
    return BufferModification(inverse_type, position, content);
}

bool Buffer::undo()
{
    if (m_history_cursor == m_history.begin())
        return false;

    --m_history_cursor;

    for (const BufferModification& modification : reversed(*m_history_cursor))
        replay_modification(modification.inverse());
}

bool Buffer::redo()
{
    if (m_history_cursor == m_history.end())
        return false;

    for (const BufferModification& modification : *m_history_cursor)
        replay_modification(modification);

    ++m_history_cursor;
}

void Buffer::replay_modification(const BufferModification& modification)
{
    switch (modification.type)
    {
    case BufferModification::Insert:
        do_insert(modification.position, modification.content);
        break;
    case BufferModification::Erase:
    {
        BufferIterator begin = modification.position;
        BufferIterator end   = begin + modification.content.size();
        assert(string(begin, end) == modification.content);
        do_erase(begin, end);
        break;
    }
    default:
        assert(false);
    }
}

void Buffer::append_modification(BufferModification&& modification)
{
    m_current_undo_group.push_back(std::move(modification));
}

Window* Buffer::get_or_create_window()
{
    if (m_windows.empty())
        m_windows.push_front(std::unique_ptr<Window>(new Window(*this)));

    return m_windows.front().get();
}

void Buffer::delete_window(Window* window)
{
    assert(&window->buffer() == this);
    auto window_it = std::find(m_windows.begin(), m_windows.end(), window);
    assert(window_it != m_windows.end());
    m_windows.erase(window_it);
}

bool Buffer::is_modified() const
{
    return m_last_save_undo_group != m_history_cursor
           or not m_current_undo_group.empty();
}

void Buffer::notify_saved()
{
    m_last_save_undo_group = m_history_cursor;
}

}