-- Copyright 2007-2013 Mitchell mitchell.att.foicica.com. See LICENSE.

local M = {}

--[[ This comment is for LuaDoc.
---
-- Filters text through shell commands.
module('_M.textadept.filter_through')]]

local cat = not WIN32 and 'cat' or 'type'
local tmpfile = _USERHOME..'/.ft'

---
-- Passes selected or all buffer text to string shell command *cmd* as standard
-- input (stdin) and replaces the input text with the command's standard output
-- (stdout).
-- Standard input is as follows:
--
-- 1. If text is selected and spans multiple lines, all text on the lines
-- containing the selection is used. However, if the end of the selection is at
-- the beginning of a line, only the EOL (end of line) characters from the
-- previous line are included as input. The rest of the line is excluded.
-- 2. If text is selected and spans a single line, only the selected text is
-- used.
-- 3. If no text is selected, the entire buffer is used.
-- @param cmd The Linux, BSD, Mac OSX, or Windows shell command to filter text
--   through.
-- @name filter_through
function M.filter_through(cmd)
  local buffer = buffer
  local s, e = buffer.selection_start, buffer.selection_end
  local input
  if s ~= e then -- use selected lines as input
    local i, j = buffer:line_from_position(s), buffer:line_from_position(e)
    if i < j then
      s = buffer:position_from_line(i)
      if buffer.column[e] > 0 then e = buffer:position_from_line(j + 1) end
    end
    input = buffer:text_range(s, e)
  else -- use whole buffer as input
    input = buffer:get_text()
  end
  local f = io.open(tmpfile, 'wb')
  f:write(input)
  f:close()
  local cmd = cat..' "'..tmpfile..'" | '..cmd
  if WIN32 then cmd = cmd:gsub('/', '\\') end
  local p = io.popen(cmd)
  if s ~= e then
    buffer.target_start, buffer.target_end = s, e
    buffer:replace_target(p:read('*all'))
    buffer:set_sel(buffer.target_start, buffer.target_end)
  else
    buffer:set_text(p:read('*all'))
    buffer:goto_pos(s)
  end
  p:close()
  os.remove(tmpfile)
end

return M