Task/763 payments algorithms

[CrazedCoding]

I am preliminarily creating this PR so people can start commenting as changes are being made, in real-time.

Here is the start of the mocha tests that I am going to create for the event-based distribution approaches:

// Please note: "income"s are the user pledges if positive, OR the needed income amount ABOVE mincome if NEGATIVE.
const distributionEvents = []

// User1 creates a group at the beginning of the month of January, 2021, and then sets an income of 100 at 10% of the way throgh the monthly cycle.
distributionEvents.push(
  {
    "type": "incomeDeclaredEvent",
    "data": {
      "name": "u1",
      "income": 100,
      "cycle": 0.1
    }
  })

// User2 joins and sets income of -50 at 20% of the way through the monthly cycle.
distributionEvents.push(
  {
    "type": "incomeDeclaredEvent",
    "data": {
      "name": "u2",
      "income": -50,
      "cycle": 0.2
    }
  })

// User3 joins and sets income of -50 at 30% of the way through the monthly cycle.
distributionEvents.push(
  {
    "type": "incomeDeclaredEvent",
    "data": {
      "name": "u3",
      "income": -50,
      "cycle": 0.3
    }
  })

// User1 pays User2 10 (out of <???>) at 40% of the way through the monthly cycle.
distributionEvents.push(
  {
    "type": "paymentEvent",
    "data": {
      "from": "u1",
      "to": "u2",
      "amount": 10,
      "cycle": 0.4
    }
  })

// User4 joins and sets income of -100 at 50% of the way through the monthly cycle.
distributionEvents.push(
  {
    "type": "incomeDeclaredEvent",
    "data": {
      "name": "u4",
      "income": -100,
      "cycle": 0.5
    }
  })

// User3 removes themselves from the group at 60% of the way through the monthly cycle. TODO: This causes UI glitches/errors for other members...
distributionEvents.push(
  {
    "type": "leaveGroup",
    "data": {
      "name": "u3"
      "cycle": 0.6
    }
  })

// User1 pays User4 5 (out of <???>) at 70% of the way through the monthly cycle.
distributionEvents.push({
    "type": "paymentEvent",
    "data": {
      "from": "u1",
      "to": "u4",
      "amount": 5,
      "cycle": 0.7
    }
  })

// User3 RE-joins the group at 75% of the way through the monthly cycle, and sets their income to -100 at 80% of the way through the monthly cycle.
distributionEvents.push({
    "type": "incomeDeclaredEvent",
    "data": {
      "name": "u3",
      "income": -100,
      "cycle": 0.8
    }
  })

These scenarios are mathematically/algorithmically designed to throw a monkey-wrench into any so-called turing-complete-solution anyone comes up with. If these can't break your solution, nothing can, BUT:

PLEASE don't just answer these scenarios with: "SOME should go to u2, and MORE/LESS should go to u3"

Terms like SOME, MORE, and LESS do not help us approach an algorithmic/arithmatic/mathematical solution.

Until we all agree on the distribution outcome (for any point in time) of these scenarios for the group-consolidated-approach, I will continue to try to create a "base-line" pro-rating/time-weighted solution (so we at least have some sort of reference point).

[CrazedCoding]

Almost done ^^

[taoeffect]

Excellent work @CrazedCoding!

Think this is very close to ready to merge. The charts and graphs seem to not be broken, which is great, and during my testing I only found an extraneous console.error (see recent comment & screenshot - I recommend testing yourself in Firefox container tabs manually to catch these things).

Can you also merge master into your PR? It will just make it easier for others to test it without having to change the dependencies multiple times.

[taoeffect]

Approved!! 🎉🎉🎉🎉