#include "window.hh"

#include <algorithm>

namespace Kakoune
{

Window::Window(Buffer& buffer)
    : m_buffer(buffer),
      m_position(0, 0),
      m_cursor(0, 0),
      m_dimensions(0, 0)
{
}

void Window::erase()
{
    m_buffer.begin_undo_group();
    if (m_selections.empty())
    {
        BufferIterator cursor = iterator_at(m_cursor);
        m_buffer.erase(cursor, cursor+1);
    }

    for (auto sel = m_selections.begin(); sel != m_selections.end(); ++sel)
    {
        m_buffer.erase(sel->begin, sel->end);
        sel->end = sel->begin;
    }
    m_buffer.end_undo_group();
}

static WindowCoord measure_string(const Window::String& string)
{
    WindowCoord result(0, 0);
    for (size_t i = 0; i < string.length(); ++i)
    {
        if (string[i] == '\n')
        {
            ++result.line;
            result.column = 0;
        }
        else
            ++result.column;
    }
    return result;
}

void Window::insert(const String& string)
{
    m_buffer.begin_undo_group();
    if (m_selections.empty())
    {
        m_buffer.insert(iterator_at(m_cursor), string);
        move_cursor(measure_string(string));
    }

    for (auto sel = m_selections.begin(); sel != m_selections.end(); ++sel)
    {
        m_buffer.insert(sel->begin, string);
        sel->begin += string.length();
        sel->end += string.length();
    }
    m_buffer.end_undo_group();
}

void Window::append(const String& string)
{
    m_buffer.begin_undo_group();
    if (m_selections.empty())
    {
        move_cursor(WindowCoord(0 , 1));
        insert(string);
    }

    for (auto sel = m_selections.begin(); sel != m_selections.end(); ++sel)
    {
        m_buffer.insert(sel->end, string);
    }
    m_buffer.end_undo_group();
}

bool Window::undo()
{
    return m_buffer.undo();
}

bool Window::redo()
{
    return m_buffer.redo();
}

BufferCoord Window::window_to_buffer(const WindowCoord& window_pos) const
{
    return BufferCoord(m_position.line + window_pos.line,
                       m_position.column + window_pos.column);
}

WindowCoord Window::buffer_to_window(const BufferCoord& buffer_pos) const
{
    return WindowCoord(buffer_pos.line - m_position.line,
                       buffer_pos.column - m_position.column);
}

BufferIterator Window::iterator_at(const WindowCoord& window_pos) const
{
    return m_buffer.iterator_at(window_to_buffer(window_pos));
}

WindowCoord Window::line_and_column_at(const BufferIterator& iterator) const
{
    return buffer_to_window(m_buffer.line_and_column_at(iterator));
}

void Window::empty_selections()
{
    m_selections.clear();
}

void Window::select(bool append, const Selector& selector)
{
    if (not append or m_selections.empty())
    {
        empty_selections();
        m_selections.push_back(selector(iterator_at(m_cursor)));
    }
    else
    {
        for (auto sel = m_selections.begin(); sel != m_selections.end(); ++sel)
        {
            sel->end = selector(sel->end).end;
        }
    }
    m_cursor = line_and_column_at(m_selections.back().end);
    scroll_to_keep_cursor_visible_ifn();
}

void Window::move_cursor(const WindowCoord& offset)
{
    BufferCoord target_position = window_to_buffer(m_cursor + offset);

    m_cursor = buffer_to_window(m_buffer.clamp(target_position));

    scroll_to_keep_cursor_visible_ifn();
}

void Window::update_display_buffer()
{
    m_display_buffer.clear();

    SelectionList sorted_selections = m_selections;
    std::sort(sorted_selections.begin(), sorted_selections.end(),
              [](const Selection& lhs, const Selection& rhs) { return lhs.begin < rhs.begin; });

    BufferIterator current_position = m_buffer.iterator_at(m_position);

    for (Selection& sel : sorted_selections)
    {
        if (current_position != sel.begin)
        {
            DisplayAtom atom;
            atom.content = m_buffer.string(current_position, sel.begin);
            m_display_buffer.append(atom);
        }
        if (sel.begin != sel.end)
        {
            DisplayAtom atom;
            atom.content = m_buffer.string(sel.begin, sel.end);
            atom.attribute = UNDERLINE;
            m_display_buffer.append(atom);
        }
        current_position = sel.end;
    }
    if (current_position != m_buffer.end())
    {
        DisplayAtom atom;
        atom.content = m_buffer.string(current_position, m_buffer.end());
        m_display_buffer.append(atom);
    }
}

void Window::set_dimensions(const WindowCoord& dimensions)
{
    m_dimensions = dimensions;
}

void Window::scroll_to_keep_cursor_visible_ifn()
{
    if (m_cursor.line < 0)
    {
        m_position.line = std::max(m_position.line + m_cursor.line, 0);
        m_cursor.line = 0;
    }
    else if (m_cursor.line >= m_dimensions.line)
    {
        m_position.line += m_cursor.line - (m_dimensions.line - 1);
        m_cursor.line = m_dimensions.line - 1;
    }

    if (m_cursor.column < 0)
    {
        m_position.column = std::max(m_position.column + m_cursor.column, 0);
        m_cursor.column = 0;
    }
    else if (m_cursor.column >= m_dimensions.column)
    {
        m_position.column += m_cursor.column - (m_dimensions.column - 1);
        m_cursor.column = m_dimensions.column - 1;
    }
}

}