feat(backend): rework fixed send fee calculation

[cozminu]

Changes proposed in this pull request

For fixed debit amounts:

• moved fee calculation before payment quote retrieval (using options.debitAmount)
• subtracted receive amount value from payment quote retrieval
• fee is calculated with the options.debitAmount.value as principal
• added fee back to the final quote to insert in db

For fixed receive amounts:

• moved fee calculation after payment quote retrieval for fixed debit amounts (as quote.debitAmount is needed, rather than the options.debitAmount). This cannot be done before retrieving the payment quote because we don't know the peer's exchange rate in advance.
• fee is calculated with quote.debitAmount.value as principal
• added to the final quote to insert in db

Changed mockQuote's receiveAmount logic a bit because one of the tests were failing:
debitAmountValue | fixedFee | basisPointFee | exchangeRate | expectedReceiveAmountValue
${200n} | ${20} | ${200} | ${0.455} | ${80n}

Fees: (200 * (200 * 0.0001)) - 20 = 24
Debit - fees: 200 - 24 = 176
Receive: 176 USD * 0.455 = 80.08 XRP (this returned 81 instead of 80 and it should be Math.floor'd instead of Math.ceil'd because the peer will deliver 80 XRP for 175.82417582 USD)

Context

fixes #3055

Checklist

• Related issues linked using fixes #number
• Tests added/updated
• Make sure that all checks pass
• Bruno collection updated (if necessary)
• Documentation issue created with user-docs label (if necessary)
• OpenAPI specs updated (if necessary)

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[github-actions]

🚀 Performance Test Results

Test Configuration:

• VUs: 4
• Duration: 1m0s

Test Metrics:

• Requests/s: 41.77
• Iterations/s: 13.94
• Failed Requests: 0.00% (0 of 2514)

📜 Logs

> performance@1.0.0 run-tests:testenv /home/runner/work/rafiki/rafiki/test/performance
> ./scripts/run-tests.sh -e test "-k" "-q" "--vus" "4" "--duration" "1m"

Cloud Nine GraphQL API is up: http://localhost:3101/graphql
Cloud Nine Wallet Address is up: http://localhost:3100/
Happy Life Bank Address is up: http://localhost:4100/
cloud-nine-wallet-test-backend already set
cloud-nine-wallet-test-auth already set
happy-life-bank-test-backend already set
happy-life-bank-test-auth already set
     data_received..................: 877 kB 15 kB/s
     data_sent......................: 1.8 MB 30 kB/s
     http_req_blocked...............: avg=6.13µs   min=2.37µs  med=5.32µs   max=285.03µs p(90)=6.17µs   p(95)=6.61µs  
     http_req_connecting............: avg=357ns    min=0s      med=0s       max=245.21µs p(90)=0s       p(95)=0s      
     http_req_duration..............: avg=95.13ms  min=11.4ms  med=78.98ms  max=628.53ms p(90)=166.59ms p(95)=193.99ms
       { expected_response:true }...: avg=95.13ms  min=11.4ms  med=78.98ms  max=628.53ms p(90)=166.59ms p(95)=193.99ms
     http_req_failed................: 0.00%  ✓ 0         ✗ 2514
     http_req_receiving.............: avg=90.55µs  min=26.89µs med=81.23µs  max=1.33ms   p(90)=115.21µs p(95)=144.25µs
     http_req_sending...............: avg=34.76µs  min=11.84µs med=28.06µs  max=2.37ms   p(90)=40.07µs  p(95)=53.1µs  
     http_req_tls_handshaking.......: avg=0s       min=0s      med=0s       max=0s       p(90)=0s       p(95)=0s      
     http_req_waiting...............: avg=95ms     min=11.27ms med=78.87ms  max=628.2ms  p(90)=166.48ms p(95)=193.9ms 
     http_reqs......................: 2514   41.773143/s
     iteration_duration.............: avg=286.66ms min=184.9ms med=273.19ms max=1.19s    p(90)=348.57ms p(95)=373.73ms
     iterations.....................: 839    13.940997/s
     vus............................: 4      min=4       max=4 
     vus_max........................: 4      min=4       max=4 

[mkurapov]

Looks good! will also request @BlairCurrey to take a look

[BlairCurrey]

Looks great. Appreciate the detailed description in the PR body.

[BlairCurrey]

I assume this was to resolve some issue with the docker trivy scan?

[cozminu]

yes