-- Copyright 2007-2010 Mitchell mitchell<att>caladbolg.net. See LICENSE.

local locale = _G.locale
local events = _G.events

---
-- Editing commands for the textadept module.
module('_m.textadept.editing', package.seeall)

-- Markdown:
-- ## Settings
--
-- * `AUTOPAIR`: Flag indicating whether or not when an opening `(`, `[`, `[`,
--   `"`, or `'` is typed, its closing complement character is automatically
--   inserted.
-- * `HIGHLIGHT_BRACES`: Flag indicating whether or not when the caret is over a
--   brace character (any of the following: `()[]{}<>`), its matching complement
--   brace is highlighted.
-- * `AUTOINDENT`: Flag indicating whether or not when the enter key is pressed,
--   the inserted line has is indented to match the level of indentation of the
--   previous line.

-- settings
AUTOPAIR = true
HIGHLIGHT_BRACES = true
AUTOINDENT = true
-- end settings

---
-- Comment strings for various lexer languages.
-- Used for the block_comment function.
-- This table is typically populated by language-specific modules.
-- @class table
-- @name comment_string
-- @see block_comment
comment_string = {}

---
-- Enclosures for enclosing or selecting ranges of text.
-- Note chars and tag enclosures are generated at runtime.
-- You can add entries to the table in language-specific modules and use the
-- 'enclose' function in key commands.
-- @class table
-- @name enclosure
-- @see enclose
enclosure = {
  dbl_quotes = { left = '"', right = '"' },
  sng_quotes = { left = "'", right = "'" },
  parens     = { left = '(', right = ')' },
  brackets   = { left = '[', right = ']' },
  braces     = { left = '{', right = '}' },
  chars      = { left = ' ', right = ' ' },
  tags       = { left = '>', right = '<' },
  tag        = { left = ' ', right = ' ' },
  single_tag = { left = '<', right = ' />' }
}

-- Character matching.
-- Used for auto-matching parentheses, brackets, braces, and quotes.
local char_matches = {
  [40] = ')', [91] = ']', [123] = '}',
  [39] = "'", [34] = '"'
}

-- Brace characters.
-- Used for going to matching brace positions.
local braces = { -- () [] {} <>
  [40] = 1, [91] = 1, [123] = 1, [60] = 1,
  [41] = 1, [93] = 1, [125] = 1, [62] = 1,
}

-- The current call tip.
-- Used for displaying call tips.
local current_call_tip = {}

events.connect('char_added',
  function(c) -- matches characters specified in char_matches
    if AUTOPAIR and char_matches[c] and buffer.selections == 1 then
      buffer:insert_text(-1, char_matches[c])
    end
  end)

events.connect('keypress',
  function(code, shift, control, alt) -- removes matched chars on backspace
    if AUTOPAIR and code == 0xff08 and buffer.selections == 1 then
      local buffer = buffer
      local current_pos = buffer.current_pos
      local c = buffer.char_at[current_pos - 1]
      if char_matches[c] and
        buffer.char_at[current_pos] == string.byte(char_matches[c]) then
        buffer:clear()
      end
    end
  end)

events.connect('update_ui',
  function() -- highlights matching braces
    local buffer = buffer
    local current_pos = buffer.current_pos
    if HIGHLIGHT_BRACES and braces[buffer.char_at[current_pos]] and
      buffer:get_style_name(buffer.style_at[current_pos]) == 'operator' then
      local pos = buffer:brace_match(current_pos)
      if pos ~= -1 then
        buffer:brace_highlight(current_pos, pos)
      else
        buffer:brace_bad_light(current_pos)
      end
    else
      buffer:brace_bad_light(-1)
    end
  end)

events.connect('char_added',
  function(char) -- auto-indent on return
    if not AUTOINDENT or char ~= 10 then return end
    local buffer = buffer
    local anchor, caret = buffer.anchor, buffer.current_pos
    local curr_line = buffer:line_from_position(caret)
    local last_line = curr_line - 1
    while last_line >= 0 and #buffer:get_line(last_line) == 1 do
      last_line = last_line - 1
    end
    if last_line >= 0 then
      local indentation = buffer.line_indentation[last_line]
      local s = buffer.line_indent_position[curr_line]
      buffer.line_indentation[curr_line] = indentation
      local e = buffer.line_indent_position[curr_line]
      local diff = e - s
      if e > s then -- move selection on
        if anchor >= s then anchor = anchor + diff end
        if caret  >= s then caret  = caret  + diff end
      elseif e < s then -- move selection back
        if anchor >= e then anchor = anchor >= s and anchor + diff or e end
        if caret  >= e then caret  = caret  >= s and caret  + diff or e end
      end
      buffer:set_sel(anchor, caret)
    end
  end)

-- local functions
local get_preceding_number

---
-- Goes to a matching brace position, selecting the text inside if specified.
-- @param select If true, selects the text between matching braces.
function match_brace(select)
  local buffer = buffer
  local caret = buffer.current_pos
  local match_pos = buffer:brace_match(caret)
  if match_pos ~= -1 then
    if select then
      if match_pos > caret then
        buffer:set_sel(caret, match_pos + 1)
      else
        buffer:set_sel(caret + 1, match_pos)
      end
    else
      buffer:goto_pos(match_pos)
    end
  end
end

---
-- Pops up an autocompletion list for the current word based on other words in
-- the document.
-- @param word_chars String of chars considered to be part of words.
function autocomplete_word(word_chars)
  local buffer = buffer
  local caret, length = buffer.current_pos, buffer.length
  local completions, c_list = {}, {}
  local buffer_text = buffer:get_text(buffer.length)
  local root = buffer_text:sub(1, caret):match('['..word_chars..']+$')
  if not root or #root == 0 then return end
  buffer.target_start, buffer.target_end = 0, buffer.length
  buffer.search_flags = 1048580 -- word start and match case
  local match_pos = buffer:search_in_target(root)
  while match_pos ~= -1 do
    local s, e = buffer_text:find('^['..word_chars..']+', match_pos + 1)
    local match = buffer_text:sub(s, e)
    if not completions[match] and #match > #root then
      c_list[#c_list + 1] = match
      completions[match] = true
    end
    buffer.target_start, buffer.target_end = match_pos + 1, buffer.length
    match_pos = buffer:search_in_target(root)
  end
  if #c_list > 0 then
    buffer:auto_c_show(#root, table.concat(c_list, ' '))
    return true
  end
end

---
-- Block comments or uncomments code with a given comment string.
-- @param comment The comment string inserted or removed from the beginning of
--   each line in the selection.
function block_comment(comment)
  local buffer = buffer
  if not comment then
    comment = comment_string[buffer:get_lexer()]
    if not comment then return end
  end
  local caret, anchor = buffer.current_pos, buffer.anchor
  if caret < anchor then anchor, caret = caret, anchor end
  local s = buffer:line_from_position(anchor)
  local e = buffer:line_from_position(caret)
  local mlines = s ~= e
  if mlines and caret == buffer:position_from_line(e) then e = e - 1 end
  buffer:begin_undo_action()
  for line = s, e do
    local pos = buffer:position_from_line(line)
    if buffer:text_range(pos, pos + #comment) == comment then
      buffer:set_sel(pos, pos + #comment)
      buffer:replace_sel('')
      caret = caret - #comment
    else
      buffer:insert_text(pos, comment)
      caret = caret + #comment
    end
  end
  buffer:end_undo_action()
  if mlines then buffer:set_sel(anchor, caret) else buffer:goto_pos(caret) end
end

---
-- Goes to the requested line.
-- @param line Optional line number to go to.
function goto_line(line)
  local buffer = buffer
  if not line then
    line =
      gui.dialog('standard-inputbox',
                 '--title', locale.M_TEXTADEPT_EDITING_GOTO_TITLE,
                 '--text', locale.M_TEXTADEPT_EDITING_GOTO_TEXT,
                 '--no-newline')
    line = tonumber(line:match('%-?%d+$'))
    if not line or line < 0 then return end
  end
  buffer:ensure_visible_enforce_policy(line - 1)
  buffer:goto_line(line - 1)
end

---
-- Prepares the buffer for saving to a file.
-- Strips trailing whitespace off of every line, ensures an ending newline, and
-- converts non-consistent EOLs.
function prepare_for_save()
  local buffer = buffer
  buffer:begin_undo_action()
  -- Strip trailing whitespace.
  local lines = buffer.line_count
  for line = 0, lines - 1 do
    local s = buffer:position_from_line(line)
    local e = buffer.line_end_position[line]
    local i = e - 1
    local c = buffer.char_at[i]
    while i >= s and c == 9 or c == 32 do
      i = i - 1
      c = buffer.char_at[i]
    end
    if i < e - 1 then
      buffer.target_start, buffer.target_end = i + 1, e
      buffer:replace_target('')
    end
  end
  -- Ensure ending newline.
  local e = buffer:position_from_line(lines)
  if lines == 1 or
    lines > 1 and e > buffer:position_from_line(lines - 1) then
    buffer:insert_text(e, '\n')
  end
  -- Convert non-consistent EOLs
  buffer:convert_eo_ls(buffer.eol_mode)
  buffer:end_undo_action()
end
events.connect('file_before_save', prepare_for_save)

---
-- Cuts or copies text ranges intelligently. (Behaves like Emacs.)
-- If no text is selected, all text from the cursor to the end of the line is
-- cut or copied as indicated by action. If there is text selected, it is cut or
-- copied.
-- @param copy If false, the text is cut. Otherwise it is copied.
function smart_cutcopy(copy)
  local buffer = buffer
  local txt = buffer:get_sel_text()
  if #txt == 0 then buffer:line_end_extend() end
  txt = buffer:get_sel_text()
  if copy then buffer:copy() else buffer:cut() end
end

---
-- Selects the current word under the caret and if action indicates, deletes it.
-- @param action Optional action to perform with selected word. If 'delete', it
--   is deleted.
function current_word(action)
  local buffer = buffer
  local s = buffer:word_start_position(buffer.current_pos)
  local e = buffer:word_end_position(buffer.current_pos)
  buffer:set_sel(s, e)
  if action == 'delete' then buffer:delete_back() end
end

---
-- Transposes characters intelligently.
-- If the caret is at the end of the current word, the two characters before
-- the caret are transposed. Otherwise the characters to the left and right of
-- the caret are transposed.
function transpose_chars()
  local buffer = buffer
  buffer:begin_undo_action()
  local caret = buffer.current_pos
  local char = buffer.char_at[caret - 1]
  buffer:delete_back()
  if caret > buffer.length or buffer.char_at[caret - 1] == 32 then
    buffer:char_left()
  else
    buffer:char_right()
  end
  buffer:insert_text(-1, string.char(char))
  buffer:end_undo_action()
  buffer:goto_pos(caret)
end

---
-- Reduces multiple characters occurances to just one.
-- If char is not given, the character to be squeezed is the one behind the
-- caret.
-- @param char The character (integer) to be used for squeezing.
function squeeze(char)
  local buffer = buffer
  if not char then char = buffer.char_at[buffer.current_pos - 1] end
  local s, e = buffer.current_pos - 1, buffer.current_pos - 1
  while buffer.char_at[s] == char do s = s - 1 end
  while buffer.char_at[e] == char do e = e + 1 end
  buffer:set_sel(s + 1, e)
  buffer:replace_sel(string.char(char))
end

---
-- Joins the current line with the line below, eliminating whitespace.
function join_lines()
  local buffer = buffer
  buffer:begin_undo_action()
  buffer:line_end()
  buffer:clear()
  buffer:add_text(' ')
  squeeze()
  buffer:end_undo_action()
end

---
-- Encloses text in an enclosure set.
-- If text is selected, it is enclosed. Otherwise, the previous word is
-- enclosed. The n previous words can be enclosed by appending n (a number) to
-- the end of the last word. When enclosing with a character, append the
-- character to the end of the word(s). To enclose previous word(s) with n
-- characters, append n (a number) to the end of character set.
-- Examples:
--   enclose this2 -> 'enclose this' (enclose in sng_quotes)
--   enclose this2**2 -> **enclose this**
-- @param str The enclosure type in enclosure.
-- @see enclosure
-- @see get_preceding_number
function enclose(str)
  local buffer = buffer
  buffer:begin_undo_action()
  local txt = buffer:get_sel_text()
  if txt == '' then
    if str == 'chars' then
      local num_chars, len_num_chars = get_preceding_number()
      for i = 1, len_num_chars do buffer:delete_back() end
      for i = 1, num_chars do buffer:char_left_extend() end
      enclosure[str].left  = buffer:get_sel_text()
      enclosure[str].right = enclosure[str].left
      buffer:delete_back()
    end
    local num_words, len_num_chars = get_preceding_number()
    for i = 1, len_num_chars do buffer:delete_back() end
    for i = 1, num_words do buffer:word_left_extend() end
    txt = buffer:get_sel_text()
  end
  local len = 0
  if str == 'tag' then
    enclosure[str].left  = '<'..txt..'>'
    enclosure[str].right = '</'..txt..'>'
    len = #txt + 3
    txt = ''
  end
  local left  = enclosure[str].left
  local right = enclosure[str].right
  buffer:replace_sel(left..txt..right)
  if str == 'tag' then buffer:goto_pos(buffer.current_pos - len) end
  buffer:end_undo_action()
end

---
-- Selects text in a specified enclosure.
-- @param str The enclosure type in enclosure.
-- @see enclosure
function select_enclosed(str)
  if not str then return end
  local buffer = buffer
  buffer:search_anchor()
  local s = buffer:search_prev(0, enclosure[str].left)
  local e = buffer:search_next(0, enclosure[str].right)
  if s and e then buffer:set_sel(s + 1, e) end
end

---
-- Grows the selection by a character amount on either end.
-- @param amount The amount to grow the selection on either end.
function grow_selection(amount)
  local buffer = buffer
  local anchor, caret = buffer.anchor, buffer.current_pos
  if anchor < caret then
    buffer:set_sel(anchor - amount, caret + amount)
  else
    buffer:set_sel(anchor + amount, caret - amount)
  end
end

---
-- Selects the current line.
function select_line()
  local buffer = buffer
  buffer:home()
  buffer:line_end_extend()
end

---
-- Selects the current paragraph.
-- Paragraphs are delimited by two or more consecutive newlines.
function select_paragraph()
  local buffer = buffer
  buffer:para_up()
  buffer:para_down_extend()
end

---
-- Selects indented blocks intelligently.
-- If no block of text is selected, all text with the current level of
-- indentation is selected. If a block of text is selected and the lines to the
-- top and bottom of it are one indentation level lower, they are added to the
-- selection. In all other cases, the behavior is the same as if no text is
-- selected.
function select_indented_block()
  local buffer = buffer
  local s = buffer:line_from_position(buffer.anchor)
  local e = buffer:line_from_position(buffer.current_pos)
  if s > e then s, e = e, s end
  local indent = buffer.line_indentation[s] - buffer.indent
  if indent < 0 then return end
  if buffer:get_sel_text() ~= '' then
    if buffer.line_indentation[s - 1] == indent and
      buffer.line_indentation[e + 1] == indent then
      s, e = s - 1, e + 1
      indent = indent + buffer.indent -- don't run while loops
    end
  end
  while buffer.line_indentation[s - 1] > indent do s = s - 1 end
  while buffer.line_indentation[e + 1] > indent do e = e + 1 end
  s = buffer:position_from_line(s)
  e = buffer.line_end_position[e]
  buffer:set_sel(s, e)
end

---
-- Selects all text with the same scope/style as under the caret.
function select_scope()
  local buffer = buffer
  local start_pos = buffer.current_pos
  local base_style = buffer.style_at[start_pos]
  local pos = start_pos - 1
  while buffer.style_at[pos] == base_style do pos = pos - 1 end
  local start_style = pos
  pos = start_pos + 1
  while buffer.style_at[pos] == base_style do pos = pos + 1 end
  buffer:set_sel(start_style + 1, pos)
end

---
-- Converts indentation between tabs and spaces.
function convert_indentation()
  local buffer = buffer
  buffer:begin_undo_action()
  for line = 0, buffer.line_count do
    local s = buffer:position_from_line(line)
    local indent = buffer.line_indentation[line]
    local indent_pos = buffer.line_indent_position[line]
    current_indentation = buffer:text_range(s, indent_pos)
    if buffer.use_tabs then
      new_indentation = ('\t'):rep(indent / buffer.tab_width)
    else
      new_indentation = (' '):rep(indent)
    end
    if current_indentation ~= new_indentation then
      buffer.target_start = s
      buffer.target_end = indent_pos
      buffer:replace_target(new_indentation)
    end
  end
  buffer:end_undo_action()
end

-- Returns the number to the left of the caret.
-- This is used for the enclose function.
-- @see enclose
get_preceding_number = function()
  local buffer = buffer
  local caret = buffer.current_pos
  local char = buffer.char_at[caret - 1]
  local txt = ''
  while tonumber(string.char(char)) do
    txt = txt..string.char(char)
    caret = caret - 1
    char = buffer.char_at[caret - 1]
  end
  return tonumber(txt) or 1, #txt
end