# Author: Daniel
# License: UNLICENSE
# Depends: [builtin git.kak], [kak-toggle (optional)]

# the purpose of this plugin is keep Kakoune's built-in git diff highlighting
# updated as changes are made to the file. The easiest way to do this would be
# to just run :git update-diff on NormalIdle .* but that's super inefficient.
# so instead we'll track via %val{timestamp}. we'll have a buffer scoped option
# git_diff_timestamp which will always be set to the value of %val{timestamp} when
# we last ran update-diff. So if the timestamp has changed, we'll run update-diff.
# This way while we still need _something_ to run on NormalIdle it won't be the entire
# perl script

# NOTE: there is an issue where an empty line-specs option causes the entire column to disappear;
# which results in a jarring visual change b/c the window width changes all of a sudden.
# I patched the builtin git.kak
# so git_diff_flags always starts with a "dummy" flag: `0|.`
# (it's impossible for a flag to be visible at line 0) but because it's not _empty_,
# the column is still drawn (it's just blank)
# IF YOU WANT THIS TOO, open the builtin git.kak,
# find this line in the update_diff() function:
#   `$flags = $ENV{"kak_timestamp"};`
# and add this line immediately after it:
#   `$flags .= " 0|.";`

declare-option -hidden int git_diff_timestamp 0

define-command git-diff-watch-enable %{
	# always enable first
	git show-diff
	hook -group git-diff-watch buffer NormalIdle .* %{
		evaluate-commands %sh{
			# only run update-diff if the file has actually changed
			if [ "$kak_timestamp" != "$kak_opt_git_diff_timestamp" ]; then
				echo "git update-diff"
				printf 'set-option buffer git_diff_timestamp %s\n' "$kak_timestamp"
			fi
		}
	}

}

define-command git-diff-watch-disable %{
	remove-hooks buffer git-diff-watch
	git hide-diff
}

# using https://codeberg.org/ficd/kak-toggle
register-toggle toggle-git-diff-watch false git-diff-watch-enable git-diff-watch-disable