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business_logic.md

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Business Logic

Clarifies ambiguous situations in the user command document.s

BUY

BUY needs a fresh quote from a user

Quotes expire in 60s

[1] ADD,userA,100     << Initialize user
[2] BUY,userA,XYZ,50  << Fails because user did not QUOTE for XYZ
[3] QUOTE,userA,XYZ   

 > 60s pass

[4] BUY,userA,XYZ,50  << Fails because Quote in 3 is stale

Can't reuse quotes from other users

[1] ADD,userA,100
[2] QUOTE,userB,XYZ
[3] BUY,userA,XYZ,200 << Fails because no quote from userA

Users cannot buy fractional stocks

Users can buy (buy_amount % stock_price) number of stocks.

[1] ADD,userA,100
[2] QUOTE,userA,XYZ   << XYZ = $15
[3] BUY,userA,XYZ,10  << Fails because user can't buy 0 stocks

Only reserve amount necessary to buy whole stocks

[1] ADD,userA,100
[2] QUOTE,userA,XYZ   << XYZ = $15
[3] BUY,userA,XYZ,50  << $45 removed from userA and placed in reserve

Triggers

Multiple triggers for same stock same account

Overwrite any pre-existing buys or sells

user triggers:
  XYZ:
    buy_amount: 100
    buy_trigger: 200
  ABC:
    buy_amount: 150
    buy_trigger: 250

send: SET_BUY_TRIGGER,user,XYZ,30

user triggers:
  XYZ:
    buy_amount: 100
    buy_trigger: 30
  ABC:
    buy_amount: 150
    buy_trigger: 250

Incomplete triggers

Both TRIGGER and AMOUNT must be set for trigger to execute

user triggers:
  XYZ:
    buy_amount: 100
    # no buy trigger

<< XYZ gets quote update and triggers for XYZ are checked >>

- No buys execute for user on XYZ

user triggers:
  XYZ:
    # no buy amount
    buy_trigger: 200

<< XYZ gets quote update and triggers for XYZ are checked >>

- No buys execute for user on XYZ

Removing triggers

Only remove the TRIGGER, keep the AMOUNT

user triggers:
  XYZ:
    buy_amount: 100
    buy_trigger: 200

send: CANCEL_SET_BUY,user,XYZ

user triggers:
  XYZ:
    buy_amount: 100
    # no buy trigger