-- helpers for selecting portions of text

function edit.mouse_loc(editor)
  local mx,my = love.mouse.getPosition()
  return edit.to_loc(editor, mx, my)
end

function Text.cut_selection_and_record_undo_event(editor)
  if editor.selection1.line == nil then return end
  local result = Text.selection(editor)
  Text.delete_selection_and_record_undo_event(editor)
  return result
end

function Text.delete_selection_and_record_undo_event(editor)
  if editor.selection1.line == nil then return end
  local minl,maxl = minmax(editor.selection1.line, editor.cursor.line)
  local before = snapshot(editor, minl, maxl)
  Text.delete_selection_without_undo(editor)
  record_undo_event(editor, {before=before, after=snapshot(editor, editor.cursor.line)})
end

function Text.delete_selection_without_undo(editor)
  if editor.selection1.line == nil then return end
  -- min,max = sorted(editor.selection1,editor.cursor)
  local minl,minp = editor.selection1.line,editor.selection1.pos
  local maxl,maxp = editor.cursor.line,editor.cursor.pos
  if minl > maxl then
    minl,maxl = maxl,minl
    minp,maxp = maxp,minp
  elseif minl == maxl then
    if minp > maxp then
      minp,maxp = maxp,minp
    end
  end
  -- update editor.cursor and editor.selection1
  editor.cursor.line = minl
  editor.cursor.pos = minp
  if edit.lt(editor.cursor, editor.screen_top) then
    editor.screen_top = edit.hor(editor, editor.cursor, editor.left)
  end
  editor.selection1 = {}
  -- delete everything between min (inclusive) and max (exclusive)
  local min_offset = Text.offset(editor.lines[minl].data, minp)
  local max_offset = Text.offset(editor.lines[maxl].data, maxp)
  if minl == maxl then
    editor.lines[minl].data = editor.lines[minl].data:sub(1, min_offset-1)..editor.lines[minl].data:sub(max_offset)
    return
  end
  assert(minl < maxl, ('minl %d not < maxl %d'):format(minl, maxl))
  local rhs = editor.lines[maxl].data:sub(max_offset)
  for i=maxl,minl+1,-1 do
    table.remove(editor.lines, i)
  end
  editor.lines[minl].data = editor.lines[minl].data:sub(1, min_offset-1)..rhs
end

function Text.selection(editor)
  if editor.selection1.line == nil then return end
  -- min,max = sorted(editor.selection1,editor.cursor)
  local minl,minp = editor.selection1.line,editor.selection1.pos
  local maxl,maxp = editor.cursor.line,editor.cursor.pos
  if minl > maxl then
    minl,maxl = maxl,minl
    minp,maxp = maxp,minp
  elseif minl == maxl then
    if minp > maxp then
      minp,maxp = maxp,minp
    end
  end
  local min_offset = Text.offset(editor.lines[minl].data, minp)
  local max_offset = Text.offset(editor.lines[maxl].data, maxp)
  if minl == maxl then
    return editor.lines[minl].data:sub(min_offset, max_offset-1)
  end
  assert(minl < maxl, ('minl %d not < maxl %d'):format(minl, maxl))
  local result = {editor.lines[minl].data:sub(min_offset)}
  for i=minl+1,maxl-1 do
    if editor.lines[i].mode == 'text' then
      table.insert(result, editor.lines[i].data)
    end
  end
  table.insert(result, editor.lines[maxl].data:sub(1, max_offset-1))
  return table.concat(result, '\n')
end

function in_selection(editor, line_index, pos, cursor)
  if editor.selection1.line == nil then return false end
  assert(cursor.mode == 'text')
  assert(editor.lines[line_index].mode == 'text')
  local curr = {mode='text', line=line_index, pos=pos}
  if edit.eq(cursor, editor.selection1) then
    return false
  elseif edit.lt(cursor, editor.selection1) then
    return edit.le(cursor, curr) and edit.lt(curr, editor.selection1)
  elseif edit.lt(editor.selection1, cursor) then
    return edit.le(editor.selection1, curr) and edit.lt(curr, cursor)
  end
end