From 08dcd814a9b887fcdd83dca59e9f54293828a9a9 Mon Sep 17 00:00:00 2001
From: Felix Endres <6112784+felixendres@users.noreply.github.com>
Date: Thu, 23 May 2024 05:56:13 +0200
Subject: [PATCH] Improve :BCommits Preview (#1525)

Reduce the preview of :BCommits to the relevant part, when used with visual selection.
Only show the part of the diff that belongs to the selection.

That makes it very easy to quickly follow the evolution of a code block.
---
 autoload/fzf/vim.vim | 26 ++++++++++++++++++--------
 1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/autoload/fzf/vim.vim b/autoload/fzf/vim.vim
index 8e9fd9f..b7ed96b 100755
--- a/autoload/fzf/vim.vim
+++ b/autoload/fzf/vim.vim
@@ -1474,14 +1474,22 @@ function! s:commits(range, buffer_local, args)
 
   let args = copy(a:args)
   let log_opts = len(args) && type(args[0]) == type('') ? remove(args, 0) : ''
+  let with_preview = !s:is_win && &columns > s:wide
 
   if len(a:range) || a:buffer_local
     if !managed
       return s:warn('The current buffer is not in the working tree')
     endif
-    let source .= len(a:range)
-      \ ? join([printf(' -L %d,%d:%s --no-patch', a:range[0], a:range[1], fzf#shellescape(current)), log_opts])
-      \ : join([' --follow', log_opts, fzf#shellescape(current)])
+    if len(a:range)
+      let source .= join([printf(' -L %d,%d:%s --no-patch', a:range[0], a:range[1], fzf#shellescape(current)), log_opts])
+      if with_preview
+        let previewparams = join([printf('log -L %d,%d:%s', a:range[0], a:range[1], fzf#shellescape(current)), log_opts])
+        let previewfilter = " | awk '/commit {1}/ {flag=1;print;next} /^[^ ]*commit/{flag=0} flag' "
+        let previewcmd = prefix . previewparams .' --color=always '. previewfilter
+      endif
+    else
+      let source .= join([' --follow', log_opts, fzf#shellescape(current)])
+    endif
     let command = 'BCommits'
   else
     let source .= join([' --graph', log_opts])
@@ -1503,12 +1511,14 @@ function! s:commits(range, buffer_local, args)
     let options.options[-1] .= ',ctrl-d'
   endif
 
-  if !s:is_win && &columns > s:wide
+  if with_preview
+    if !len(a:range)
+      let orderfile = tempname()
+      call writefile([current[len(s:git_root)+1:]], orderfile)
+      let previewcmd = 'echo {} | grep -o "[a-f0-9]\{7,\}" | head -1 | xargs ' . prefix . 'show -O'.fzf#shellescape(orderfile).' --format=format: --color=always '
+    endif
     let suffix = executable('delta') ? '| delta --width $FZF_PREVIEW_COLUMNS' : ''
-    let orderfile = tempname()
-    call writefile([current[len(s:git_root)+1:]], orderfile)
-    call extend(options.options,
-    \ ['--preview', 'echo {} | grep -o "[a-f0-9]\{7,\}" | head -1 | xargs ' . prefix . 'show -O'.fzf#shellescape(orderfile).' --format=format: --color=always ' . suffix])
+    call extend(options.options, ['--preview', previewcmd . suffix])
   endif
 
   return s:fzf(a:buffer_local ? 'bcommits' : 'commits', options, args)