Preview the current commit when searching git log (#26)

When searching git log, preview the commit for the current line with git show. Output is colorized. Also, since the preview pane eats up a lot of space, trimmed git log lines by using a shorter date format and removing a space used for padding.

README.md

@@ -12,7 +12,7 @@ A plugin that integrates [fzf](https://github.com/junegunn/fzf) into your [fish]
 
 ![git status select](/images/git_status_select.png)
 
-> Search the current repository's **git log** - `Ctrl+Alt+l` (l for log, Alt to prevent overriding clear screen)
+> Search and preview the current repository's **git log** - `Ctrl+Alt+l` (l for log, Alt to prevent overriding clear screen)
 
 ![git log search](/images/git_log_search.png)
 

functions/__fzf_search_git_log.fish

@@ -6,8 +6,8 @@ function __fzf_search_git_log --description "Search the git log of the current g
         set selected_log_line (
             # see documentation for git format placeholders at https://git-scm.com/docs/git-log#Documentation/git-log.txt-emnem
             # %h gives you the abbreviated commit hash, which is useful for saving screen space, but we will have to expand it later below
-            git log --color=always --format=format:'%C(bold blue)%h%C(reset) - %C(cyan)%aD%C(reset) %C(yellow)%d%C(reset) %C(normal)%s%C(reset)   %C(dim normal)[%an]%C(reset)' | \
-            fzf --ansi --tiebreak=index
+            git log --color=always --format=format:'%C(bold blue)%h%C(reset) - %C(cyan)%as%C(reset) %C(yellow)%d%C(reset) %C(normal)%s%C(reset)  %C(dim normal)[%an]%C(reset)' | \
+            fzf --ansi --tiebreak=index --preview='git show --color=always (string split --max 1 " " {})[1]'
         )
         if test $status -eq 0
             set abbreviated_commit_hash (string split --max 1 " " $selected_log_line)[1]