Add nvim floating window support (replaces #3314) (#3470)

* Add nvim floating window hover support
* Add configuration for float to replace preview
* preview#ShowFloating: qualify local variables
* Configure floating preview usecases individually

Also:
  * Extract floating preview to its own file.
  * Ignore 'stay_here' option. Moving into the floating preview window
    seems confusing at best.
  * Re-use existing floating preview window if it's still up.
  * Flush out floating preview documentation.

* Watch cursor position changes per window

Floating previews open a new window, so when that window is written to,
it moves briefly there at a different position than the original window.
This makes repeated positions detected when positions are tracked at a
s: level. Instead, we change the variable to window scoped, which only
fires a message if the cursor has changed from the last position in
*that window*.

* g:ale_floating_preview cleanup
* floating_preview: add ALEDetail tests
* Fix fecs test missing runtime call
* Add ALEHover floating preview tests

Co-authored-by: Jan-Grimo Sobez <jan-grimo.sobez@phys.chem.ethz.ch>

8 files changed, 330 insertions, 7 deletions

diff --git a/autoload/ale/cursor.vim b/autoload/ale/cursor.vim
index 9ca6fb15..e8478e93 100644
--- a/autoload/ale/cursor.vim
+++ b/autoload/ale/cursor.vim
@@ -9,7 +9,6 @@ let g:ale_echo_delay = get(g:, 'ale_echo_delay', 10)
 let g:ale_echo_msg_format = get(g:, 'ale_echo_msg_format', '%code: %%s')
 
 let s:cursor_timer = -1
-let s:last_pos = [0, 0, 0]
 
 function! ale#cursor#TruncatedEcho(original_message) abort
     let l:message = a:original_message
@@ -118,14 +117,18 @@ function! ale#cursor#EchoCursorWarningWithDelay() abort
 
     let l:pos = getpos('.')[0:2]
 
+    if !exists('w:last_pos')
+        let w:last_pos = [0, 0, 0]
+    endif
+
     " Check the current buffer, line, and column number against the last
     " recorded position. If the position has actually changed, *then*
     " we should echo something. Otherwise we can end up doing processing
     " the echo message far too frequently.
-    if l:pos != s:last_pos
+    if l:pos != w:last_pos
         let l:delay = ale#Var(l:buffer, 'echo_delay')
 
-        let s:last_pos = l:pos
+        let w:last_pos = l:pos
         let s:cursor_timer = timer_start(
         \   l:delay,
         \   function('ale#cursor#EchoCursorWarning')
@@ -139,11 +142,16 @@ function! s:ShowCursorDetailForItem(loc, options) abort
     let s:last_detailed_line = line('.')
     let l:message = get(a:loc, 'detail', a:loc.text)
     let l:lines = split(l:message, "\n")
-    call ale#preview#Show(l:lines, {'stay_here': l:stay_here})
 
-    " Clear the echo message if we manually displayed details.
-    if !l:stay_here
-        execute 'echo'
+    if g:ale_floating_preview || g:ale_detail_to_floating_preview
+        call ale#floating_preview#Show(l:lines)
+    else
+        call ale#preview#Show(l:lines, {'stay_here': l:stay_here})
+
+        " Clear the echo message if we manually displayed details.
+        if !l:stay_here
+            execute 'echo'
+        endif
     endif
 endfunction
 
diff --git a/autoload/ale/floating_preview.vim b/autoload/ale/floating_preview.vim
new file mode 100644
index 00000000..e6a75689
--- /dev/null
+++ b/autoload/ale/floating_preview.vim
@@ -0,0 +1,91 @@
+" Author: Jan-Grimo Sobez <jan-grimo.sobez@phys.chem.ethz.ch>
+" Author: Kevin Clark <kevin.clark@gmail.com>
+" Description: Floating preview window for showing whatever information in.
+
+" Precondition: exists('*nvim_open_win')
+
+function! ale#floating_preview#Show(lines, ...) abort
+    if !exists('*nvim_open_win')
+        execute 'echom ''Floating windows not supported in this vim instance.'''
+
+        return
+    endif
+
+    " Remove the close autocmd so it doesn't happen mid update
+    augroup ale_floating_preview_window
+        autocmd!
+    augroup END
+
+    let l:options = get(a:000, 0, {})
+
+    " Only create a new window if we need it
+    if !exists('w:preview') || index(nvim_list_wins(), w:preview['id']) is# -1
+        call s:Create(l:options)
+    else
+        call nvim_buf_set_option(w:preview['buffer'], 'modifiable', v:true)
+    endif
+
+    " Execute commands in window context
+    let l:parent_window = nvim_get_current_win()
+
+    call nvim_set_current_win(w:preview['id'])
+
+    for l:command in get(l:options, 'commands', [])
+        call execute(l:command)
+    endfor
+
+    call nvim_set_current_win(l:parent_window)
+
+    " Return to parent context on move
+    augroup ale_floating_preview_window
+        autocmd!
+
+        if g:ale_close_preview_on_insert
+            autocmd CursorMoved,TabLeave,WinLeave,InsertEnter <buffer> ++once call s:Close()
+        else
+            autocmd CursorMoved,TabLeave,WinLeave <buffer> ++once call s:Close()
+        endif
+    augroup END
+
+    let l:width = max(map(copy(a:lines), 'strdisplaywidth(v:val)'))
+    let l:height = min([len(a:lines), 10])
+    call nvim_win_set_width(w:preview['id'], l:width)
+    call nvim_win_set_height(w:preview['id'], l:height)
+
+    call nvim_buf_set_lines(w:preview['buffer'], 0, -1, v:false, a:lines)
+    call nvim_buf_set_option(w:preview['buffer'], 'modified', v:false)
+    call nvim_buf_set_option(w:preview['buffer'], 'modifiable', v:false)
+endfunction
+
+function! s:Create(options) abort
+    let l:buffer = nvim_create_buf(v:false, v:false)
+    let l:winid = nvim_open_win(l:buffer, v:false, {
+    \ 'relative': 'cursor',
+    \ 'row': 1,
+    \ 'col': 0,
+    \ 'width': 42,
+    \ 'height': 4,
+    \ 'style': 'minimal'
+    \ })
+    call nvim_buf_set_option(l:buffer, 'buftype', 'acwrite')
+    call nvim_buf_set_option(l:buffer, 'bufhidden', 'delete')
+    call nvim_buf_set_option(l:buffer, 'swapfile', v:false)
+    call nvim_buf_set_option(l:buffer, 'filetype', get(a:options, 'filetype', 'ale-preview'))
+
+    let w:preview = {'id': l:winid, 'buffer': l:buffer}
+endfunction
+
+function! s:Close() abort
+    if !exists('w:preview')
+        return
+    endif
+
+    call setbufvar(w:preview['buffer'], '&modified', 0)
+
+    if win_id2win(w:preview['id']) > 0
+        execute win_id2win(w:preview['id']).'wincmd c'
+    endif
+
+    unlet w:preview
+endfunction
+
diff --git a/autoload/ale/hover.vim b/autoload/ale/hover.vim
index 1d38f3b9..cb0379fd 100644
--- a/autoload/ale/hover.vim
+++ b/autoload/ale/hover.vim
@@ -46,6 +46,10 @@ function! ale#hover#HandleTSServerResponse(conn_id, response) abort
                 call balloon_show(a:response.body.displayString)
             elseif get(l:options, 'truncated_echo', 0)
                 call ale#cursor#TruncatedEcho(split(a:response.body.displayString, "\n")[0])
+            elseif g:ale_hover_to_floating_preview || g:ale_floating_preview
+                call ale#floating_preview#Show(split(a:response.body.displayString, "\n"), {
+                \   'filetype': 'ale-preview.message',
+                \})
             elseif g:ale_hover_to_preview
                 call ale#preview#Show(split(a:response.body.displayString, "\n"), {
                 \   'filetype': 'ale-preview.message',
@@ -226,6 +230,11 @@ function! ale#hover#HandleLSPResponse(conn_id, response) abort
                 call balloon_show(join(l:lines, "\n"))
             elseif get(l:options, 'truncated_echo', 0)
                 call ale#cursor#TruncatedEcho(l:lines[0])
+            elseif g:ale_hover_to_floating_preview || g:ale_floating_preview
+                call ale#floating_preview#Show(l:lines, {
+                \   'filetype': 'ale-preview.message',
+                \   'commands': l:commands,
+                \})
             elseif g:ale_hover_to_preview
                 call ale#preview#Show(l:lines, {
                 \   'filetype': 'ale-preview.message',
diff --git a/doc/ale.txt b/doc/ale.txt
index 767d000d..a77407a1 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -646,6 +646,9 @@ problem will be displayed in a balloon instead of hover information.
 Hover information can be displayed in the preview window instead by setting
 |g:ale_hover_to_preview| to `1`.
 
+When using Neovim, if |g:ale_hover_to_floating_preview| or |g:ale_floating_preview|
+is set to 1, the hover information will show in a floating window.
+
 For Vim 8.1+ terminals, mouse hovering is disabled by default. Enabling
 |balloonexpr| commands in terminals can cause scrolling issues in terminals,
 so ALE will not attempt to show balloons unless |g:ale_set_balloons| is set to
@@ -954,6 +957,15 @@ g:ale_default_navigation                             *g:ale_default_navigation*
   buffer, such as for |ALEFindReferences|, or |ALEGoToDefinition|.
 
 
+g:ale_detail_to_floating_preview                            *g:ale_detail_to_floating_preview*
+                                                            *b:ale_detail_to_floating_preview*
+  Type: |Number|
+  Default: `0`
+
+  When this option is set to `1`, Neovim will use a floating window for
+  ALEDetail output.
+
+
 g:ale_disable_lsp                                           *g:ale_disable_lsp*
                                                             *b:ale_disable_lsp*
 
@@ -1177,6 +1189,16 @@ g:ale_fix_on_save_ignore                             *g:ale_fix_on_save_ignore*
   let g:ale_fix_on_save_ignore = [g:AddBar]
 <
 
+g:ale_floating_preview                                       *g:ale_floating_preview*
+
+  Type: |Number|
+  Default: `0`
+
+  When set to `1`, Neovim will use a floating window for ale's preview window.
+  This is equivalent to setting |g:ale_hover_to_floating_preview| and
+  |g:ale_detail_to_floating_preview| to `1`.
+
+
 g:ale_history_enabled                                   *g:ale_history_enabled*
 
   Type: |Number|
@@ -1235,6 +1257,14 @@ g:ale_hover_to_preview                                 *g:ale_hover_to_preview*
   instead of in balloons or the message line.
 
 
+g:ale_hover_to_floating_preview                       *g:ale_hover_to_floating_preview*
+                                                      *b:ale_hover_to_floating_preview*
+  Type: |Number|
+  Default: `0`
+
+  If set to `1`, Neovim will use floating windows for hover messages.
+
+
 g:ale_keep_list_window_open                       *g:ale_keep_list_window_open*
                                                   *b:ale_keep_list_window_open*
   Type: |Number|
diff --git a/plugin/ale.vim b/plugin/ale.vim
index 5b7be116..1735715d 100644
--- a/plugin/ale.vim
+++ b/plugin/ale.vim
@@ -138,6 +138,15 @@ let g:ale_set_balloons = get(g:, 'ale_set_balloons', has('balloon_eval') && has(
 " Use preview window for hover messages.
 let g:ale_hover_to_preview = get(g:, 'ale_hover_to_preview', 0)
 
+" Float preview windows in Neovim
+let g:ale_floating_preview = get(g:, 'ale_floating_preview', 0)
+
+" Hovers use floating windows in Neovim
+let g:ale_hover_to_floating_preview = get(g:, 'ale_hover_to_floating_preview', 0)
+
+" Detail uses floating windows in Neovim
+let g:ale_detail_to_floating_preview = get(g:, 'ale_detail_to_floating_preview', 0)
+
 " This flag can be set to 0 to disable warnings for trailing whitespace
 let g:ale_warn_about_trailing_whitespace = get(g:, 'ale_warn_about_trailing_whitespace', 1)
 " This flag can be set to 0 to disable warnings for trailing blank lines
diff --git a/test/command_callback/test_fecs_command_callback.vader b/test/command_callback/test_fecs_command_callback.vader
index f70ad084..4287d324 100644
--- a/test/command_callback/test_fecs_command_callback.vader
+++ b/test/command_callback/test_fecs_command_callback.vader
@@ -1,5 +1,6 @@
 Before:
   call ale#assert#SetUpLinterTest('javascript', 'fecs')
+  runtime autoload/ale/handlers/fecs.vim
 
 After:
   call ale#assert#TearDownLinterTest()
diff --git a/test/test_floating_preview.vader b/test/test_floating_preview.vader
new file mode 100644
index 00000000..43415556
--- /dev/null
+++ b/test/test_floating_preview.vader
@@ -0,0 +1,92 @@
+Before:
+  let g:ale_floating_preview = 0
+  let g:ale_hover_to_floating_preview = 0
+  let g:ale_detail_to_floating_preview = 0
+
+  runtime autoload/ale/floating_preview.vim
+
+  let g:floated_lines = []
+  let g:floating_preview_show_called = 0
+
+  " Stub out so we can track the call
+  function! ale#floating_preview#Show(lines, ...) abort
+    let g:floating_preview_show_called = 1
+    let g:floated_lines = a:lines
+  endfunction
+
+  let g:ale_buffer_info = {
+  \ bufnr('%'): {
+  \   'loclist': [
+  \     {
+  \       'lnum': 1,
+  \       'col': 10,
+  \       'bufnr': bufnr('%'),
+  \       'vcol': 0,
+  \       'linter_name': 'notalinter',
+  \       'nr': -1,
+  \       'type': 'E',
+  \       'code': 'semi',
+  \       'text': "Missing semicolon.\r",
+  \       'detail': "Every statement should end with a semicolon\nsecond line",
+  \     },
+  \   ],
+  \ }
+  \}
+
+  call ale#linter#Reset()
+  call ale#linter#PreventLoading('javascript')
+
+After:
+  Restore
+
+  let g:ale_floating_preview = 0
+  let g:ale_hover_to_floating_preview = 0
+  let g:ale_detail_to_floating_preview = 0
+
+  call cursor(1, 1)
+
+  let g:ale_buffer_info = {}
+
+  " Close the preview window if it's open.
+  if &filetype is# 'ale-preview'
+    noautocmd :q!
+  endif
+
+  call ale#linter#Reset()
+
+
+Given javascript(A file with warnings/errors):
+  var x = 3 + 12345678
+  var x = 5*2 + parseInt("10");
+  // comment
+
+Execute(Floating preview is used with ALEDetail when g:ale_floating_preview set):
+  let g:ale_floating_preview = 1
+
+  call cursor(1, 10)
+
+  ALEDetail
+
+  let expected = ["Every statement should end with a semicolon", "second line"]
+
+  AssertEqual 1, g:floating_preview_show_called
+  AssertEqual expected, g:floated_lines
+
+Execute(Floating preview is used with ALEDetail when g:ale_detail_to_floating_preview set):
+  let g:ale_detail_to_floating_preview = 1
+
+  call cursor(1, 10)
+
+  ALEDetail
+
+  let expected = ["Every statement should end with a semicolon", "second line"]
+
+  AssertEqual 1, g:floating_preview_show_called
+  AssertEqual expected, g:floated_lines
+
+Execute(Floating preview is not used with ALEDetail by default):
+  call cursor(1, 10)
+
+  ALEDetail
+
+  AssertEqual 0, g:floating_preview_show_called
diff --git a/test/test_hover.vader b/test/test_hover.vader
index ed756396..7a9c8d91 100644
--- a/test/test_hover.vader
+++ b/test/test_hover.vader
@@ -7,9 +7,25 @@ Before:
   let g:item_list = []
   let g:show_message_arg_list = []
 
+  let g:ale_floating_preview = 0
+  let g:ale_hover_to_floating_preview = 0
+  let g:ale_detail_to_floating_preview = 0
+
   runtime autoload/ale/linter.vim
   runtime autoload/ale/lsp.vim
+  runtime autoload/ale/lsp_linter.vim
   runtime autoload/ale/util.vim
+  runtime autoload/ale/floating_preview.vim
+  runtime autoload/ale/hover.vim
+
+  let g:floated_lines = []
+  let g:floating_preview_show_called = 0
+
+  " Stub out so we can track the call
+  function! ale#floating_preview#Show(lines, ...) abort
+    let g:floating_preview_show_called = 1
+    let g:floated_lines = a:lines
+  endfunction
 
   function! ale#lsp_linter#StartLSP(buffer, linter, callback) abort
     let g:Callback = a:callback
@@ -50,6 +66,7 @@ Before:
     \)
   endfunction
 
+
 After:
   call ale#hover#SetMap({})
   call ale#test#RestoreDirectory()
@@ -65,6 +82,7 @@ After:
   runtime autoload/ale/lsp_linter.vim
   runtime autoload/ale/lsp.vim
   runtime autoload/ale/util.vim
+  runtime autoload/ale/floating_preview.vim
 
 Given python(Some Python file):
   foo
@@ -168,6 +186,28 @@ Execute(LSP hover response with lists of strings and marked strings should be ha
   \], g:show_message_arg_list
   AssertEqual {}, ale#hover#GetMap()
 
+Execute(LSP hover with ale_floating_preview should float):
+  let g:ale_floating_preview = 1
+
+  call HandleValidLSPResult({'contents': "the message\ncontinuing"})
+
+  AssertEqual 1, g:floating_preview_show_called
+  AssertEqual ["the message", "continuing"], g:floated_lines
+
+Execute(LSP hover ale_hover_to_floating_preview should float):
+  let g:ale_hover_to_floating_preview = 1
+
+  call HandleValidLSPResult({'contents': "the message\ncontinuing"})
+
+  AssertEqual 1, g:floating_preview_show_called
+  AssertEqual ["the message", "continuing"], g:floated_lines
+
+
+Execute(LSP hover by default should not float):
+  call HandleValidLSPResult({'contents': "the message\ncontinuing"})
+
+  AssertEqual 0, g:floating_preview_show_called
+
 Execute(tsserver responses for documentation requests should be handled):
   call ale#hover#SetMap({3: {'show_documentation': 1, 'buffer': bufnr('')}})
 
@@ -187,3 +227,46 @@ Execute(tsserver responses for documentation requests should be handled):
   " The preview window should show the text.
   AssertEqual ['foo is a very good method'], ale#test#GetPreviewWindowText()
   silent! pclose
+
+Execute(hover with show_documentation should be in the preview window, not floating):
+  let g:ale_hover_to_floating_preview = 1
+  let g:ale_floating_preview = 1
+
+  call ale#hover#SetMap({3: {'show_documentation': 1, 'buffer': bufnr('')}})
+
+  call ale#hover#HandleTSServerResponse(
+  \ 1,
+  \ {
+  \   'command': 'quickinfo',
+  \   'request_seq': 3,
+  \   'success': v:true,
+  \   'body': {
+  \     'documentation': 'foo is a very good method',
+  \     'displayString': 'foo bar ',
+  \   },
+  \ }
+  \)
+
+  let expected = ["Every statement should end with a semicolon", "second line"]
+
+  AssertEqual 0, g:floating_preview_show_called
+
+Execute(TSServer hover without show_documentation and ale_floating_preview should float):
+  let g:ale_floating_preview = 1
+
+  call ale#hover#SetMap({3: {'buffer': bufnr('')}})
+
+  call ale#hover#HandleTSServerResponse(
+  \ 1,
+  \ {
+  \   'command': 'quickinfo',
+  \   'request_seq': 3,
+  \   'success': v:true,
+  \   'body': {
+  \     'displayString': "the message\ncontinuing",
+  \   },
+  \ }
+  \)
+
+  AssertEqual 1, g:floating_preview_show_called
+  AssertEqual ["the message", "continuing"], g:floated_lines