feat(plugins): add `zbell` plugin to notify when commands end (#3034)

Closes #3034

plugins/zbell/README.md

+# zbell plugin
+
+This plugin prints a bell character when a command finishes if it has been
+running for longer than a specified duration.
+
+To use it, add `zbell` to the plugins array in your zshrc file:
+
+```zsh
+plugins=(... zbell)
+```
+
+## Settings
+
+These settings need to be set in your zshrc file, before Oh My Zsh is sourced.
+
+- `zbell_duration`: duration in seconds after which to consider notifying
+  the end of a command. Default: 15 seconds.
+
+- `zbell_ignore`: if there are programs that you know run long that you
+  don't want to bell after, then add them to the `zbell_ignore` array.
+  By default, `$EDITOR` and `$PAGER` are ignored:
+
+  ```zsh
+  zbell_ignore=($EDITOR $PAGER)
+  ```
+
+## Author
+
+Adapted from an original version by [Jean-Philippe Ouellet](https://github.com/jpouellet).
+Made available under the ISC license.

plugins/zbell/zbell.plugin.zsh

+#!/usr/bin/env zsh
+
+# This script prints a bell character when a command finishes
+# if it has been running for longer than $zbell_duration seconds.
+# If there are programs that you know run long that you don't
+# want to bell after, then add them to $zbell_ignore.
+#
+# This script uses only zsh builtins so its fast, there's no needless
+# forking, and its only dependency is zsh and its standard modules
+#
+# Written by Jean-Philippe Ouellet <jpo@vt.edu>
+# Made available under the ISC license.
+
+# only do this if we're in an interactive shell
+[[ -o interactive ]] || return
+
+# get $EPOCHSECONDS. builtins are faster than date(1)
+zmodload zsh/datetime || return
+
+# make sure we can register hooks
+autoload -Uz add-zsh-hook || return
+
+# make sure we can do regexp replace
+autoload -Uz regexp-replace || return
+
+# initialize zbell_duration if not set
+(( ${+zbell_duration} )) || zbell_duration=15
+
+# initialize zbell_ignore if not set
+(( ${+zbell_ignore} )) || zbell_ignore=($EDITOR $PAGER)
+
+# initialize it because otherwise we compare a date and an empty string
+# the first time we see the prompt. it's fine to have lastcmd empty on the
+# initial run because it evaluates to an empty string, and splitting an
+# empty string just results in an empty array.
+zbell_timestamp=$EPOCHSECONDS
+
+# default notification function
+# $1: command
+# $2: duration in seconds
+zbell_notify() {
+	type notify-send > /dev/null && \
+		notify-send -i terminal "Command completed in ${2}s:" $1
+	print -n "\a"
+}
+
+# right before we begin to execute something, store the time it started at
+zbell_begin() {
+	zbell_timestamp=$EPOCHSECONDS
+	zbell_lastcmd=$1
+}
+
+# when it finishes, if it's been running longer than $zbell_duration,
+# and we dont have an ignored command in the line, then print a bell.
+zbell_end() {
+	local cmd_duration=$(( $EPOCHSECONDS - $zbell_timestamp ))
+	local ran_long=$(( $cmd_duration >= $zbell_duration ))
+
+	local zbell_lastcmd_tmp="$zbell_lastcmd"
+	regexp-replace zbell_lastcmd_tmp '^sudo ' ''
+
+	[[ $zbell_last_timestamp == $zbell_timestamp ]] && return
+
+	[[ $zbell_lastcmd_tmp == "" ]] && return
+
+	zbell_last_timestamp=$zbell_timestamp
+
+	local has_ignored_cmd=0
+	for cmd in ${(s:;:)zbell_lastcmd_tmp//|/;}; do
+		words=(${(z)cmd})
+		util=${words[1]}
+		if (( ${zbell_ignore[(i)$util]} <= ${#zbell_ignore} )); then
+			has_ignored_cmd=1
+			break
+		fi
+	done
+
+	(( ! $has_ignored_cmd && ran_long )) && zbell_notify $zbell_lastcmd $cmd_duration
+}
+
+# register the functions as hooks
+add-zsh-hook preexec zbell_begin
+add-zsh-hook precmd zbell_end