local core = require "core"
local command = require "core.command"
local common = require "core.common"
local config = require "core.config"
local translate = require "core.doc.translate"
local DocView = require "core.docview"


local function dv()
  return core.active_view
end


local function doc()
  return core.active_view.doc
end


local function doc_multiline_selections(sort)
  local iter, state, idx, line1, col1, line2, col2 = doc():get_selections(sort)
  return function()
    idx, line1, col1, line2, col2 = iter(state, idx)
    if idx and line2 > line1 and col2 == 1 then
      line2 = line2 - 1
      col2 = #doc().lines[line2]
    end
    return idx, line1, col1, line2, col2
  end
end

local function append_line_if_last_line(line)
  if line >= #doc().lines then
    doc():insert(line, math.huge, "\n")
  end
end

local function save(filename)
  local abs_filename
  if filename then
    filename = core.normalize_to_project_dir(filename)
    abs_filename = core.project_absolute_path(filename)
  end
  doc():save(filename, abs_filename)
  local saved_filename = doc().filename
  core.log("Saved \"%s\"", saved_filename)
end

local function cut_or_copy(delete)
  local full_text = ""
  local text = ""
  core.cursor_clipboard = {}
  core.cursor_clipboard_whole_line = {}
  for idx, line1, col1, line2, col2 in doc():get_selections() do
    if line1 ~= line2 or col1 ~= col2 then
      text = doc():get_text(line1, col1, line2, col2)
      full_text = full_text == "" and text or (full_text .. " " .. text)
      core.cursor_clipboard_whole_line[idx] = false
      if delete then
        doc():delete_to_cursor(idx, 0)
      end
    else -- Cut/copy whole line
      text = doc().lines[line1]
      full_text = full_text == "" and text or (full_text .. text)
      core.cursor_clipboard_whole_line[idx] = true
      if delete then
        if line1 < #doc().lines then
          doc():remove(line1, 1, line1 + 1, 1)
        else
          doc():remove(line1 - 1, math.huge, line1, math.huge)
        end
      end
    end
    core.cursor_clipboard[idx] = text
  end
  core.cursor_clipboard["full"] = full_text
  system.set_clipboard(full_text)
end

local function split_cursor(direction)
  local new_cursors = {}
  for _, line1, col1 in doc():get_selections() do
    if line1 + direction >= 1 and line1 + direction <= #doc().lines then
      table.insert(new_cursors, { line1 + direction, col1 })
    end
  end
  for i,v in ipairs(new_cursors) do doc():add_selection(v[1], v[2]) end
  core.blink_reset()
end

local function set_cursor(x, y, snap_type)
  local line, col = dv():resolve_screen_position(x, y)
  doc():set_selection(line, col, line, col)
  if snap_type == "word" or snap_type == "lines" then
    command.perform("doc:select-" .. snap_type)
  end
  dv().mouse_selecting = { line, col, snap_type }
  core.blink_reset()
end

local function line_comment(comment, line1, col1, line2, col2)
  local start_comment = (type(comment) == 'table' and comment[1] or comment) .. " "
  local end_comment = (type(comment) == 'table' and " " .. comment[2])
  local uncomment = true
  local start_offset = math.huge
  for line = line1, line2 do
    local text = doc().lines[line]
    local s = text:find("%S")
    if s then
      local cs, ce = text:find(start_comment, s, true)
      if cs ~= s then
        uncomment = false
      end
      start_offset = math.min(start_offset, s)
    end
  end

  local end_line = col2 == #doc().lines[line2]
  for line = line1, line2 do
    local text = doc().lines[line]
    local s = text:find("%S")
    if s and uncomment then
      if end_comment and text:sub(#text - #end_comment, #text - 1) == end_comment then
        doc():remove(line, #text - #end_comment, line, #text)
      end
      local cs, ce = text:find(start_comment, s, true)
      if ce then
        doc():remove(line, cs, line, ce + 1)
      end
    elseif s then
      doc():insert(line, start_offset, start_comment)
      if end_comment then
        doc():insert(line, #doc().lines[line], " " .. comment[2])
      end
    end
  end
  col1 = col1 + (col1 > start_offset and #start_comment or 0) * (uncomment and -1 or 1)
  col2 = col2 + (col2 > start_offset and #start_comment or 0) * (uncomment and -1 or 1)
  if end_comment and end_line then
    col2 = col2 + #end_comment * (uncomment and -1 or 1)
  end
  return line1, col1, line2, col2
end

local function block_comment(comment, line1, col1, line2, col2)
  -- automatically skip spaces
  local word_start = doc():get_text(line1, col1, line1, math.huge):find("%S")
  local word_end = doc():get_text(line2, 1, line2, col2):find("%s*$")
  col1 = col1 + (word_start and (word_start - 1) or 0)
  col2 = word_end and word_end or col2

  local block_start = doc():get_text(line1, col1, line1, col1 + #comment[1])
  local block_end = doc():get_text(line2, col2 - #comment[2], line2, col2)

  if block_start == comment[1] and block_end == comment[2] then
    -- remove up to 1 whitespace after the comment
    local start_len, stop_len = #comment[1], #comment[2]
    if doc():get_text(line1, col1 + #comment[1], line1, col1 + #comment[1] + 1):find("%s$") then
      start_len = start_len + 1
    end
    if doc():get_text(line2, col2 - #comment[2] - 1, line2, col2):find("^%s") then
      stop_len = stop_len + 1
    end

    doc():remove(line1, col1, line1, col1 + start_len)
    col2 = col2 - (line1 == line2 and start_len or 0)
    doc():remove(line2, col2 - stop_len, line2, col2)

    return line1, col1, line2, col2 - stop_len
  else
    doc():insert(line1, col1, comment[1] .. " ")
    col2 = col2 + (line1 == line2 and (#comment[1] + 1) or 0)
    doc():insert(line2, col2, " " .. comment[2])

    return line1, col1, line2, col2 + #comment[2] + 1
  end
end

local commands = {
  ["doc:select-none"] = function()
    local line, col = doc():get_selection()
    doc():set_selection(line, col)
  end,
  
  ["doc:cut"] = function()
    cut_or_copy(true)
  end,

  ["doc:copy"] = function()
    cut_or_copy(false)
  end,

  ["doc:undo"] = function()
    doc():undo()
  end,

  ["doc:redo"] = function()
    doc():redo()
  end,

  ["doc:paste"] = function()
    local clipboard = system.get_clipboard()
    -- If the clipboard has changed since our last look, use that instead
    local external_paste = core.cursor_clipboard["full"] ~= clipboard
    if external_paste then
      core.cursor_clipboard = {}
      core.cursor_clipboard_whole_line = {}
    end
    local value, whole_line
    for idx, line1, col1, line2, col2 in doc():get_selections() do
      if #core.cursor_clipboard_whole_line == (#doc().selections/4) then
        value = core.cursor_clipboard[idx]
        whole_line = core.cursor_clipboard_whole_line[idx] == true
      else
        value = clipboard
        whole_line = not external_paste and clipboard:find("\n") ~= nil
      end
      if whole_line then
        doc():insert(line1, 1, value:gsub("\r", ""))
        if col1 == 1 then
          doc():move_to_cursor(idx, #value)
        end
      else
        doc():text_input(value:gsub("\r", ""), idx)
      end
    end
  end,

  ["doc:newline"] = function()
    for idx, line, col in doc():get_selections(false, true) do
      local indent = doc().lines[line]:match("^[\t ]*")
      if col <= #indent then
        indent = indent:sub(#indent + 2 - col)
      end
      doc():text_input("\n" .. indent, idx)
    end
  end,

  ["doc:newline-below"] = function()
    for idx, line in doc():get_selections(false, true) do
      local indent = doc().lines[line]:match("^[\t ]*")
      doc():insert(line, math.huge, "\n" .. indent)
      doc():set_selections(idx, line + 1, math.huge)
    end
  end,

  ["doc:newline-above"] = function()
    for idx, line in doc():get_selections(false, true) do
      local indent = doc().lines[line]:match("^[\t ]*")
      doc():insert(line, 1, indent .. "\n")
      doc():set_selections(idx, line, math.huge)
    end
  end,

  ["doc:delete"] = function()
    for idx, line1, col1, line2, col2 in doc():get_selections() do
      if line1 == line2 and col1 == col2 and doc().lines[line1]:find("^%s*$", col1) then
        doc():remove(line1, col1, line1, math.huge)
      end
      doc():delete_to_cursor(idx, translate.next_char)
    end
  end,

  ["doc:backspace"] = function()
    local _, indent_size = doc():get_indent_info()
    for idx, line1, col1, line2, col2 in doc():get_selections() do
      if line1 == line2 and col1 == col2 then
        local text = doc():get_text(line1, 1, line1, col1)
        if #text >= indent_size and text:find("^ *$") then
          doc():delete_to_cursor(idx, 0, -indent_size)
          return
        end
      end
      doc():delete_to_cursor(idx, translate.previous_char)
    end
  end,

  ["doc:select-all"] = function()
    doc():set_selection(1, 1, math.huge, math.huge)
    -- avoid triggering DocView:scroll_to_make_visible
    dv().last_line1 = 1
    dv().last_col1 = 1
    dv().last_line2 = #doc().lines
    dv().last_col2 = #doc().lines[#doc().lines]
  end,

  ["doc:select-lines"] = function()
    for idx, line1, _, line2 in doc():get_selections(true) do
      append_line_if_last_line(line2)
      doc():set_selections(idx, line1, 1, line2 + 1, 1)
    end
  end,

  ["doc:select-word"] = function()
    for idx, line1, col1 in doc():get_selections(true) do
      local line1, col1 = translate.start_of_word(doc(), line1, col1)
      local line2, col2 = translate.end_of_word(doc(), line1, col1)
      doc():set_selections(idx, line2, col2, line1, col1)
    end
  end,

  ["doc:join-lines"] = function()
    for idx, line1, col1, line2, col2 in doc():get_selections(true) do
      if line1 == line2 then line2 = line2 + 1 end
      local text = doc():get_text(line1, 1, line2, math.huge)
      text = text:gsub("(.-)\n[\t ]*", function(x)
        return x:find("^%s*$") and x or x .. " "
      end)
      doc():insert(line1, 1, text)
      doc():remove(line1, #text + 1, line2, math.huge)
      if line1 ~= line2 or col1 ~= col2 then
        doc():set_selections(idx, line1, math.huge)
      end
    end
  end,

  ["doc:indent"] = function()
    for idx, line1, col1, line2, col2 in doc_multiline_selections(true) do
      local l1, c1, l2, c2 = doc():indent_text(false, line1, col1, line2, col2)
      if l1 then
        doc():set_selections(idx, l1, c1, l2, c2)
      end
    end
  end,

  ["doc:unindent"] = function()
    for idx, line1, col1, line2, col2 in doc_multiline_selections(true) do
      local l1, c1, l2, c2 = doc():indent_text(true, line1, col1, line2, col2)
      if l1 then
        doc():set_selections(idx, l1, c1, l2, c2)
      end
    end
  end,

  ["doc:duplicate-lines"] = function()
    for idx, line1, col1, line2, col2 in doc_multiline_selections(true) do
      append_line_if_last_line(line2)
      local text = doc():get_text(line1, 1, line2 + 1, 1)
      doc():insert(line2 + 1, 1, text)
      local n = line2 - line1 + 1
      doc():set_selections(idx, line1 + n, col1, line2 + n, col2)
    end
  end,

  ["doc:delete-lines"] = function()
    for idx, line1, col1, line2, col2 in doc_multiline_selections(true) do
      append_line_if_last_line(line2)
      doc():remove(line1, 1, line2 + 1, 1)
      doc():set_selections(idx, line1, col1)
    end
  end,

  ["doc:move-lines-up"] = function()
    for idx, line1, col1, line2, col2 in doc_multiline_selections(true) do
      append_line_if_last_line(line2)
      if line1 > 1 then
        local text = doc().lines[line1 - 1]
        doc():insert(line2 + 1, 1, text)
        doc():remove(line1 - 1, 1, line1, 1)
        doc():set_selections(idx, line1 - 1, col1, line2 - 1, col2)
      end
    end
  end,

  ["doc:move-lines-down"] = function()
    for idx, line1, col1, line2, col2 in doc_multiline_selections(true) do
      append_line_if_last_line(line2 + 1)
      if line2 < #doc().lines then
        local text = doc().lines[line2 + 1]
        doc():remove(line2 + 1, 1, line2 + 2, 1)
        doc():insert(line1, 1, text)
        doc():set_selections(idx, line1 + 1, col1, line2 + 1, col2)
      end
    end
  end,

  ["doc:toggle-block-comments"] = function()
    local comment = doc().syntax.block_comment
    if not comment then
      if doc().syntax.comment then
        command.perform "doc:toggle-line-comments"
      end
      return
    end

    for idx, line1, col1, line2, col2 in doc_multiline_selections(true) do
      -- if nothing is selected, toggle the whole line
      if line1 == line2 and col1 == col2 then
        col1 = 1
        col2 = #doc().lines[line2]
      end
      doc():set_selections(idx, block_comment(comment, line1, col1, line2, col2))
    end
  end,

  ["doc:toggle-line-comments"] = function()
    local comment = doc().syntax.comment or doc().syntax.block_comment
    if comment then
      for idx, line1, col1, line2, col2 in doc_multiline_selections(true) do
        doc():set_selections(idx, line_comment(comment, line1, col1, line2, col2))
      end
    end
  end,

  ["doc:upper-case"] = function()
    doc():replace(string.upper)
  end,

  ["doc:lower-case"] = function()
    doc():replace(string.lower)
  end,

  ["doc:go-to-line"] = function()
    local dv = dv()

    local items
    local function init_items()
      if items then return end
      items = {}
      local mt = { __tostring = function(x) return x.text end }
      for i, line in ipairs(dv.doc.lines) do
        local item = { text = line:sub(1, -2), line = i, info = "line: " .. i }
        table.insert(items, setmetatable(item, mt))
      end
    end

    core.command_view:enter("Go To Line", function(text, item)
      local line = item and item.line or tonumber(text)
      if not line then
        core.error("Invalid line number or unmatched string")
        return
      end
      dv.doc:set_selection(line, 1  )
      dv:scroll_to_line(line, true)

    end, function(text)
      if not text:find("^%d*$") then
        init_items()
        return common.fuzzy_match(items, text)
      end
    end)
  end,

  ["doc:toggle-line-ending"] = function()
    doc().crlf = not doc().crlf
  end,

  ["doc:save-as"] = function()
    local last_doc = core.last_active_view and core.last_active_view.doc
    if doc().filename then
      core.command_view:set_text(doc().filename)
    elseif last_doc and last_doc.filename then
      local dirname, filename = core.last_active_view.doc.abs_filename:match("(.*)[/\\](.+)$")
      core.command_view:set_text(core.normalize_to_project_dir(dirname) .. PATHSEP)
    end
    core.command_view:enter("Save As", function(filename)
      save(common.home_expand(filename))
    end, function (text)
      return common.home_encode_list(common.path_suggest(common.home_expand(text)))
    end)
  end,

  ["doc:save"] = function()
    if doc().filename then
      save()
    else
      command.perform("doc:save-as")
    end
  end,

  ["file:rename"] = function()
    local old_filename = doc().filename
    if not old_filename then
      core.error("Cannot rename unsaved doc")
      return
    end
    core.command_view:set_text(old_filename)
    core.command_view:enter("Rename", function(filename)
      save(common.home_expand(filename))
      core.log("Renamed \"%s\" to \"%s\"", old_filename, filename)
      if filename ~= old_filename then
        os.remove(old_filename)
      end
    end, function (text)
      return common.home_encode_list(common.path_suggest(common.home_expand(text)))
    end)
  end,


  ["file:delete"] = function()
    local filename = doc().abs_filename
    if not filename then
      core.error("Cannot remove unsaved doc")
      return
    end
    for i,docview in ipairs(core.get_views_referencing_doc(doc())) do
      local node = core.root_view.root_node:get_node_for_view(docview)
      node:close_view(core.root_view.root_node, docview)
    end
    os.remove(filename)
    core.log("Removed \"%s\"", filename)
  end,

  ["doc:select-to-cursor"] = function(x, y, clicks)
    local line1, col1 = select(3, doc():get_selection())
    local line2, col2 = dv():resolve_screen_position(x, y)
    dv().mouse_selecting = { line1, col1, nil }
    doc():set_selection(line2, col2, line1, col1)
  end,

  ["doc:set-cursor"] = function(x, y)
    set_cursor(x, y, "set")
  end,

  ["doc:set-cursor-word"] = function(x, y)
    set_cursor(x, y, "word")
  end,

  ["doc:set-cursor-line"] = function(x, y, clicks)
    set_cursor(x, y, "lines")
  end,

  ["doc:split-cursor"] = function(x, y, clicks)
    local line, col = dv():resolve_screen_position(x, y)
    local removal_target = nil
    for idx, line1, col1 in doc():get_selections(true) do
      if line1 == line and col1 == col and #doc().selections > 4 then
        removal_target = idx
      end
    end
    if removal_target then
      doc():remove_selection(removal_target)
    else
      doc():add_selection(line, col, line, col)
    end
    dv().mouse_selecting = { line, col, "set" }
  end,

  ["doc:create-cursor-previous-line"] = function()
    split_cursor(-1)
    doc():merge_cursors()
  end,

  ["doc:create-cursor-next-line"] = function()
    split_cursor(1)
    doc():merge_cursors()
  end

}


local translations = {
  ["previous-char"] = translate,
  ["next-char"] = translate,
  ["previous-word-start"] = translate,
  ["next-word-end"] = translate,
  ["previous-block-start"] = translate,
  ["next-block-end"] = translate,
  ["start-of-doc"] = translate,
  ["end-of-doc"] = translate,
  ["start-of-line"] = translate,
  ["end-of-line"] = translate,
  ["start-of-word"] = translate,
  ["start-of-indentation"] = translate,
  ["end-of-word"] = translate,
  ["previous-line"] = DocView.translate,
  ["next-line"] = DocView.translate,
  ["previous-page"] = DocView.translate,
  ["next-page"] = DocView.translate,
}

for name, obj in pairs(translations) do
  commands["doc:move-to-" .. name] = function() doc():move_to(obj[name:gsub("-", "_")], dv()) end
  commands["doc:select-to-" .. name] = function() doc():select_to(obj[name:gsub("-", "_")], dv()) end
  commands["doc:delete-to-" .. name] = function() doc():delete_to(obj[name:gsub("-", "_")], dv()) end
end

commands["doc:move-to-previous-char"] = function()
  for idx, line1, col1, line2, col2 in doc():get_selections(true) do
    if line1 ~= line2 or col1 ~= col2 then
      doc():set_selections(idx, line1, col1)
    else
      doc():move_to_cursor(idx, translate.previous_char)
    end
  end
end

commands["doc:move-to-next-char"] = function()
  for idx, line1, col1, line2, col2 in doc():get_selections(true) do
    if line1 ~= line2 or col1 ~= col2 then
      doc():set_selections(idx, line2, col2)
    else
      doc():move_to_cursor(idx, translate.next_char)
    end
  end
end

command.add("core.docview", commands)