Update Shopify Inventory From Slack Messages

Start whenever a message is posted in one of the private channels used by each location. The MESA Slack app must be a member of every channel it should listen to.

Split the message text on the | character. Read the command word (SOLD OUT, AVAILABLE, ADD, REMOVE or SET), the number if there is one, and the product name, trimmed and case-insensitive. Look up the Slack channel ID in a fixed map of channel ID to Shopify location ID, and return command, quantity, product name and location ID. Return an empty command if the text doesn't match the pattern or the channel isn't in the map.

Continue only when the parsed command is not empty and the location ID was found, so ordinary conversation in the channel never touches inventory.

Look up products whose title matches the product name from the message and take the first variant. If nothing matches, stop here so inventory is never changed for the wrong item.

SOLD OUT and SET go to a set path, AVAILABLE goes to a set path with the restock quantity you choose (for example 99), ADD and REMOVE go to an adjust path.

On the set path, set the variant's available inventory at the matched location to 0 for SOLD OUT, to the default restock number for AVAILABLE, or to the number given for SET.

On the adjust path, change the variant's available inventory at the matched location by the number given: positive for ADD, negative for REMOVE.

Add a check mark reaction to the original message so staff can see the change went through without leaving the channel.