[bug] Transfer origin/destination swap when template value changed to 0

[spencerkoo]

Specs:

• Samsung S23 Ultra
• App Version 3.7.3.2

EDIT: I found the reason

• This seems to actually be something around the original account selected BEFORE selecting that the template should be a transfer template
• When you go through the original steps included below without the part about swapping the origin and destination, it works fine
• I noticed that the color of the template (based on the color on the account) always is the color of the original account selected prior to changing the template to be of the transfer type transaction
• So, it appears that when creating a new transaction from the template, the originally selected account (prior to changing it to a transfer template - even on the first save) is ALWAYS the from/origin WHEN the template amount is zero

IGNORE BELOW, but leaving my original notes for context around cases when this was happening.

Steps to recreate:

• Create a new template
• Change the account
• THEN make the template a transfer template
• Swap the origin and destination
• Set that template's monetary value to something non-zero
• Edit the template
• Change the monetary value to 0
• The list view of the template looks correct with the "from/origin" and "to/destination" being the same as before the edit
• However, when editing or creating a new transaction from the template, the "from/origin" and the "to/destination" are swapped

When this does not occur:

• It seems to work fine if you save the original template with a monetary value of 0
• Even after editing the template to have a non-zero monetary value and vice versa a few times, the "from/origin" and "to/destination" remained the same

[mtotschnig]

The reason behind this behavior is that when you swap the origin and destination, in the background My Expenses actually does not swap anything, but changes the sign of the amount, which works when the amount is non-zero, because transferring a negative amount from A to B is equivalent with transferring this amount from B to A. But when the value is 0, this concept breaks. To solve this some non-trivial refactoring is needed.

[spencerkoo]

That makes sense. Appreciate the extra context around why the behavior happens.