fix: use better defaults when position = 'bottom'

1. Swap the default borders, because they assumed the prompt at the top
   and the match listing underneath:

       ┌ CommandT [fd] ─────────────┐ prompt border characters:
       │>                           │ { '┌', '─', '┐', '│', '┤', '─', '├', '│' }
       ├────────────────────────────┤
       │> CODE_OF_CONDUCT.md        │ match listing border
       │  CONTRIBUTING.md           │ characters:
       │  doc/command-t-ruby.txt    │ { '', '', '', '│', '┘', '─', '└', '│' }
       │  doc/command-t.txt         │
       └────────────────────────────┘

   When the prompt is at the bottom and the match listing is above (ie.
   when `position = 'bottom'` is set), the borders need to get swapped:

       ┌────────────────────────────┐
       │> CODE_OF_CONDUCT.md        │ match listing border
       │  CONTRIBUTING.md           │ characters:
       │  doc/command-t-ruby.txt    │ { '┌', '─', '┐', '│', '┤', '─', '├', '│' }
       │  doc/command-t.txt         │
       ├────────────────────────────┤
       │>                           │ prompt border characters:
       └ CommandT [fd] ─────────────┘ { '', '', '', '│', '┘', '─', '└', '│' }

2. Likewise, when `position = 'bottom'` is set, we need to change the
   prompt's `title` to be a `footer` instead.

Closes: #436

Author: wincent

lua/wincent/commandt/init.lua

@@ -630,7 +630,7 @@ local default_options = {
   traverse = 'none', -- 'file', 'pwd' or 'none'.
 }
 
-local _options = copy(default_options)
+local _options = nil
 
 -- Have to add some of these explicitly otherwise the ones with `nil` defaults
 -- (eg. `threads`) won't come through.
@@ -639,7 +639,7 @@ local allowed_options = concat(keys(default_options), {
 })
 
 local get_directory = function()
-  local options = _options -- No need for deep copy provided by `commandt.options()`.
+  local options = commandt.options()
   if options.traverse == 'file' then
     local file = vim.fn.expand('%:p:h') -- If no current file, returns current dir.
     return require('wincent.commandt.private.find_root')(file, options.root_markers)
@@ -652,8 +652,16 @@ end
 
 commandt._directory = get_directory
 
-commandt.default_options = function()
-  return copy(default_options)
+commandt.default_options = function(options)
+  local result = copy(default_options)
+
+  -- Swap border definitions if `position = 'bottom'` is set.
+  if type(options) == 'table' and options.position == 'bottom' then
+    result.match_listing.border = default_options.prompt.border
+    result.prompt.border = default_options.match_listing.border
+  end
+
+  return result
 end
 
 commandt.file_finder = function(directory)
@@ -702,7 +710,7 @@ local sanitize_options = function(options, base)
   end
 
   local validate = require('wincent.commandt.private.validate')
-  errors = merge(errors, validate('', nil, options, options_spec, default_options))
+  errors = merge(errors, validate('', nil, options, options_spec, commandt.default_options(options)))
   return options, errors
 end
 
@@ -765,11 +773,11 @@ commandt.on_open = on_open
 commandt.open = smart_open
 
 commandt.options = function()
-  return copy(_options)
+  return copy(_options or commandt.default_options())
 end
 
 commandt.setup = function(options)
-  local sanitized_options, errors = sanitize_options(options, _options)
+  local sanitized_options, errors = sanitize_options(options, _options or commandt.default_options(options))
   _options = sanitized_options
 
   if vim.g.CommandTPreferredImplementation == 'ruby' then

lua/wincent/commandt/private/match_listing.lua

@@ -174,6 +174,7 @@ function MatchListing:show()
           self:update(self._results, { selected = self._selected })
         end
       end,
+      position = self._position,
       selection_highlight = self._selection_highlight,
       title = '',
       top = top,

lua/wincent/commandt/private/prompt.lua

@@ -99,6 +99,7 @@ function Prompt:show()
         self._window = nil
       end,
       on_leave = self._on_leave,
+      position = self._position,
       title = self:title(),
       top = top,
     })

lua/wincent/commandt/private/window.lua

@@ -48,6 +48,9 @@ local validate_options = function(options)
   if options.on_resize ~= nil and type(options.on_resize) ~= 'function' then
     error('Window.new(): `on_resize` must be a function')
   end
+  if options.position ~= 'bottom' and options.position ~= 'center' and options.position ~= 'top' then
+    error("Window.new(): `position` must be 'bottom', 'center', or 'top'")
+  end
   if options.selection_highlight ~= nil and type(options.selection_highlight) ~= 'string' then
     error('Window.new(): `selection_highlight` must be a string')
   end
@@ -68,6 +71,7 @@ function Window.new(options)
     on_close = nil,
     on_leave = nil,
     on_resize = nil,
+    position = 'top',
     prompt = '> ', -- Has no effect unless `buftype` is 'prompt'.
     selection_highlight = 'PmenuSel',
     title = 'Command-T', -- Set to '' to suppress.
@@ -90,6 +94,7 @@ function Window.new(options)
     _on_leave = options.on_leave,
     _on_resize = options.on_resize,
     _padded_title = options.title ~= '' and (' ' .. options.title .. ' ') or '',
+    _position = options.position,
     _prompt = options.prompt,
     _resize_autocmd = nil,
     _selection_highlight = options.selection_highlight,
@@ -203,7 +208,8 @@ function Window:set_title(title)
   self:_reposition()
   if self._main_window then
     vim.api.nvim_win_set_config(self._main_window, {
-      title = { { self._padded_title, 'FloatBorder' } },
+      title = self._position ~= 'bottom' and { { self._padded_title, 'FloatBorder' } } or nil,
+      footer = self._position == 'bottom' and { { self._padded_title, 'FloatBorder' } } or nil,
     })
   end
 end
@@ -269,7 +275,8 @@ function Window:show()
         noautocmd = true,
         relative = 'editor',
         style = 'minimal',
-        title = { { self._padded_title, 'FloatBorder' } },
+        title = self._position ~= 'bottom' and { { self._padded_title, 'FloatBorder' } } or nil,
+        footer = self._position == 'bottom' and { { self._padded_title, 'FloatBorder' } } or nil,
       }, position)
     )
     if self._main_window == 0 then