gitcha#GitSHAComplete(): Use `complete()` to open popup menu (WIP)

Work in progress

Rough code for a working implementation using `complete()` instead of
'completefunc'.

Rejigger `start` and make a new `base` variable since we can no longer
get it as an argument.

Correctly reset 'completeopt' to its original user value after opening
the popup menu.

Return an empty string from the function as recommended by

    :h complete()

2 files changed, 28 insertions, 19 deletions

diff --git a/autoload/gitcha.vim b/autoload/gitcha.vim
index e5543f7..c2e30b1 100644
--- a/autoload/gitcha.vim
+++ b/autoload/gitcha.vim
@@ -4,32 +4,36 @@ let s:old_completefunc = &completefunc
 let s:old_completeopt = &completeopt
 
 " Completion for Git SHAs in the current repository
-function! gitcha#GitSHAComplete(findstart, base)
-	if a:findstart
+function! gitcha#GitSHAComplete()
+	" if a:findstart
 		" locate the start of the word
 		let line = getline('.')
-		let start = col('.') - 1
-		while start > 0 && line[start - 1] =~ '[0-9a-f]'
+		let start = col('.')
+		while start > 0 && line[start - 2] =~ '[0-9a-f]'
 			let start -= 1
 		endwhile
-		return start
-	endif
-
-	" Restore user completion function
-	let &completefunc = s:old_completefunc
-	" let &completeopt = s:old_completeopt
+		" return start
+	" endif
 
 	" Match Git SHAs in the current repository
 	let matches = []
 	let revs = system('git rev-list --all --pretty=oneline --no-abbrev-commit')
+	let base = line[start - 1 : col('.') - 1]
 
 	for m in s:BuildMatchDictionary(revs)
-		if m['word'] =~ '^' . a:base
+		if m['word'] =~ '^' . base
 			call add(matches, m)
 		endif
 	endfor
 
-	return matches
+	" echom start
+	" echom string(matches)
+	" let &completeopt = 'menu,pattern,menuone'
+	set completeopt=menu,menuone,preview
+	call complete(start, matches)
+	" call complete(col('.'), matches)
+	let &completeopt = s:old_completeopt
+	return ''
 endfunction
 
 " Takes rev-list output from:
@@ -58,7 +62,9 @@ endfunction
 
 " Allow mappings to initiate completion
 function! gitcha#StartGitSHACompletion()
-	set completefunc=gitcha#GitSHAComplete
-	set completeopt=menu,menuone,preview
-	return "\<C-x>\<C-u>"
+	" call gitcha#GitSHAComplete()
+	" return ''
+	" set completefunc=gitcha#GitSHAComplete
+	" set completeopt=menu,menuone,preview
+	" return "\<C-x>\<C-u>"
 endfunction
diff --git a/ftplugin/gitcommit/gitcha.vim b/ftplugin/gitcommit/gitcha.vim
index 19f4a0b..9be271d 100644
--- a/ftplugin/gitcommit/gitcha.vim
+++ b/ftplugin/gitcommit/gitcha.vim
@@ -8,10 +8,13 @@ if exists('g:no_plugin_maps') || exists('g:no_gitcha_maps')
 	finish
 endif
 
-if !hasmapto('<Plug>GitchaCompleteSHA')
-	imap <buffer> <C-x><C-s> <Plug>GitchaCompleteSHA
-endif
+" if !hasmapto('<Plug>GitchaCompleteSHA')
+" 	imap <buffer> <C-x><C-s> <Plug>GitchaCompleteSHA
+" endif
 
-inoremap <buffer> <expr> <Plug>GitchaCompleteSHA gitcha#StartGitSHACompletion()
+" inoremap <buffer> <Plug>GitchaCompleteSHA <C-r>=gitcha#StartGitSHACompletion()<CR>
+" inoremap <buffer> <Plug>GitchaCompleteSHA <C-r>=gitcha#GitSHAComplete()<CR>
+" inoremap <buffer> <C-x><C-s> <C-r>=gitcha#GitSHAComplete()<CR>
+inoremap <C-x><C-s> <C-r>=gitcha#GitSHAComplete()<CR>
 
 let b:undo_ftplugin = 'iunmap <buffer> <C-x><C-s>'