This mod will make an automatic announcement to the Local Defense channel when you get attacked by an enemy player. There is a cooldown time to prevent spamming of the channel.
It will also play an Alarm warning sound to alert you to the attack.
It reports all the pertinent information it can, but if you have something else targeted, it can't retrieve specific info (such as race/class/level). It will report that info at the first opportunity it can (if you target them or even mouse over them).

If you don't have Cosmos installed, you can set many of the options using slash commands:

Usage: /alarmsystem [command] [on/off/toggle]

Commands:
state - Enable/Disable the entire AddOn
cooldown - set the cooldown in seconds between shouts
sound - Play a sound when attacked by an enemy player
ping - Send map Ping when attacked
fireworks - Attempt to launch Fireworks when attacked by an enemy player
showguild - Include guild information when announcing attacker
untargeted - Include info on attackers that are not targeted
leveldiff - Do not announce attackers this many levels below you. (0 = Announce all levels)
death - Announce Death Instead of Attacks
sendlocal - Announce to the Local Defense Channel
sendguild - Announce to the Guild Channel
sendparty - Announce to the Party Channel
sendraid - Announce to the Raid Channel

For example'/alarmsystem state on' will turn it on and'/alarmsystem sendguild on' will send announcements to the Guild channel

Feel free to use any of this code in other mods, or to modify this AddOn itself. My only request is that you send me your modifications.