--codedit text blocks: vertically aligned text between two subsequent text positions. selection and editing.
--line1 and line2 must be valid, subsequent lines. col1 and col2 can be anything.
local buffer = require'codedit_buffer'
local str = require'codedit_str'

--clamped line segment on a line that intersects the rectangle formed by two arbitrary text positions.
function buffer:block_cols(line, line1, col1, line2, col2)
	local col1 = self:aligned_col(line, line1, col1)
	local col2 = self:aligned_col(line, line2, col2)
	--the aligned columns could end up switched because the visual columns of col1 and col2 could be switched.
	if col1 > col2 then
		col1, col2 = col2, col1
	end
	--restrict columns to the available text
	local last_col = self:last_col(line)
	col1 = math.min(math.max(col1, 1), last_col + 1)
	col2 = math.min(math.max(col2, 1), last_col + 1)
	return col1, col2
end

--select the block between two subsequent text positions as a multi-line string
function buffer:select_block(line1, col1, line2, col2)
	local lines = {}
	for line = line1, line2 do
		local tcol1, tcol2 = self:block_cols(line, line1, col1, line2, col2)
		table.insert(lines, self:sub(line, tcol1, tcol2 - 1))
	end
	return lines
end

--insert a multi-line string as a block at some position in the text. return the position after the string.
function buffer:insert_block(line1, col1, s)
	local line = line1
	local line2, col2
	local vcol = self:visual_col(line1, col1)
	for _,s in str.lines(s) do
		line2, col2 = self:insert_string(line, self:real_col(line, vcol), s)
		line = line + 1
	end
	return line2, col2
end

--remove the block between two subsequent positions in the text
function buffer:remove_block(line1, col1, line2, col2)
	for line = line1, line2 do
		local tcol1, tcol2 = self:block_cols(line, line1, col1, line2, col2)
		self:remove_string(line, tcol1, line, tcol2)
	end
end

--indent the block between two subsequent positions in the text
--returns max(visual-length(added-text)).
function buffer:indent_block(line1, col1, line2, col2, use_tab)
	local vcol = self:visual_col(line1, col1)
	for line = line1, line2 do
		local col = self:real_col(line, vcol)
		self:indent(line, col, use_tab)
	end
end

--outdent the block between two subsequent positions in the text
function buffer:outdent_block(line1, col1, line2, col2)
	local vcol = self:visual_col(line1, col1)
	for line = line1, line2 do
		local col = self:real_col(line, vcol)
		self:outdent(line, col)
	end
end

--reflow a block to its width. return the position after the last inserted character.
function buffer:reflow_block(line1, col1, line2, col2, line_width, tabsize, align, wrap)
	local lines = self:select_block(line1, col1, line2, col2)
	if true or not line_width then --TODO: test/finish this
		local vcol1 = self:visual_col(line1, col1)
		local vcol2 = self:visual_col(line2, col2)
		line_width = vcol2 - vcol1
	end
	local lines = str.reflow(lines, line_width, tabsize, align, wrap)
	self:remove_block(line1, col1, line2, col2)
	return self:insert_block(line1, col1, self:contents(lines))
end


if not ... then require'codedit_demo' end