feat(crowdfund): add ability to rage quit

[0xble]

Describe the feature you would like

Inspired by the rage quit feature from MolochDAO, allow crowdfund contributors to "rage quit" by exiting from crowdfunds they've contributed to and receiving back their original contribution amount before the crowdfund has been finalized.

Additional context

No response

[addyxvii]

I started working on this, and was wondering the preferred way of making a pr since I don't believe I permissions to push a new branch in the repo.

Thanks!

[0xble]

I started working on this, and was wondering the preferred way of making a pr since I don't believe I permissions to push a new branch in the repo.

Thanks!

Hey, thanks for the interest!

To push a PR you'll have to fork this repo and create a PR from your fork, but just want to give a heads up that keeping the previousTotalContributions field stored for every contribution up-to-date when contributors can withdraw their contributions does seem to make implementing this tricky.

[addyxvii]

What's the reason previousTotalContributions needs to be up to date, and not just removed when a user withdraws? For preserving metrics on a crowdfund? My first pass I had just removed that contributors mapping

[0xble]

What's the reason previousTotalContributions needs to be up to date, and not just removed when a user withdraws? For preserving metrics on a crowdfund? My first pass I had just removed that contributors mapping

It's used to determine whether a contributors contribution was used or not

[addyxvii]

I was being thick but get it now,
currently there is the _contributionsByContributor mapping, but no array of contributors, and that would be needed to update every contributors previousTotalContributions without that being updated the amount of contributions, used and/or owed to a contributor would be incorrect as soon as someone withdrew their contribution.

[0xble]

I was being thick but get it now, currently there is the _contributionsByContributor mapping, but no array of contributors, and that would be needed to update every contributors previousTotalContributions without that being updated the amount of contributions, used and/or owed to a contributor would be incorrect as soon as someone withdrew their contribution.

Yes, but storing an array of every contributors would be impractical. Perhaps you could store a new variable like totalContributionsWithdrawn and factor it into all the places where contribution accounting occurs?

[addyxvii]

I opened a PR here I tried to add labels, but don't think I have permission