Reconciliation

// Chapter 11: check a provider's settlement report against the books.
package main

import (
    "fmt"
    "log"
    "strings"
    "time"

    "github.com/otyang/humanblnk"
    "github.com/otyang/humanblnk/docs/examples/demo"
    "github.com/otyang/humanblnk/money"
)

func main() {
    ctx, hb := demo.Setup()
    ada := demo.Customer(ctx, hb, "ada", demo.NGN)

    // Two deposits you recorded from Paystack webhooks.
    refs := []string{humanblnk.Reference("deposit", "paystack", "ps_a_"+demo.Run), humanblnk.Reference("deposit", "paystack", "ps_b_"+demo.Run)}
    for i, amount := range []string{"10000", "2500"} {
        m := money.MustParse(amount, demo.NGN)
        if _, err := hb.Transactions.Record(ctx, humanblnk.Transaction{
            Ref: refs[i], From: humanblnk.Single(humanblnk.ClearingAccount("paystack"), m), To: humanblnk.Single(humanblnk.AccountRef(ada.ID), m),
            Description: "Bank transfer",
        }); err != nil {
            log.Fatal(err)
        }
    }

    // 1. What counts as a match. Make the rule once and reuse it.
    rule, err := hb.Reconciliation.AddRule(ctx, humanblnk.MatchRule{
        Name: "paystack: amount and reference " + demo.Run,
        Criteria: []humanblnk.Criterion{
            {Field: humanblnk.MatchAmount, Op: humanblnk.MatchEquals},
            {Field: humanblnk.MatchReference, Op: humanblnk.MatchEquals},
        },
    })
    if err != nil {
        log.Fatal(err)
    }

    // 2. Paystack's report: the two deposits, and one you never recorded.
    // Line ids are the provider's, and must be unique across every statement.
    report := []humanblnk.StatementLine{
        {ID: "stl_1_" + demo.Run, Amount: money.MustParse("10000", demo.NGN), Reference: refs[0], Date: time.Now(), Source: "paystack"},
        {ID: "stl_2_" + demo.Run, Amount: money.MustParse("2500", demo.NGN), Reference: refs[1], Date: time.Now(), Source: "paystack"},
        {ID: "stl_3_" + demo.Run, Amount: money.MustParse("7000", demo.NGN), Reference: "deposit:paystack:ps_missing_" + demo.Run, Date: time.Now(), Source: "paystack"},
    }
    run, err := hb.Reconciliation.RunLines(ctx, report, humanblnk.Run{Rules: []humanblnk.RuleID{rule.ID}})
    if err != nil {
        log.Fatal(err)
    }

    // 3. It runs in the background: poll for the result.
    var res humanblnk.RunResult
    for range 50 {
        if res, err = hb.Reconciliation.Result(ctx, run); err == nil && (res.Status == "completed" || res.Status == "failed") {
            break
        }
        time.Sleep(200 * time.Millisecond)
    }
    fmt.Printf("run %s: %s, %d matched, %d unmatched\n", res.ID, res.Status, res.Matched, res.Unmatched)

    // A bigger report comes as a file: CSV or JSON with the columns id,
    // amount, currency, reference, description and date, in major units.
    csv := "id,amount,currency,reference,description,date\n" +
        "stl_file_1_" + demo.Run + ",10000,NGN," + refs[0] + ",Bank transfer," + time.Now().UTC().Format(time.RFC3339) + "\n"
    statement, lines, err := hb.Reconciliation.Upload(ctx, "paystack", "settlement.csv", strings.NewReader(csv))
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println("uploaded", statement, "with", lines, "line(s); run it with Reconciliation.Run")

    if err := hb.Reconciliation.RemoveRule(ctx, rule.ID); err != nil {
        log.Fatal(err)
    }
}

run recon_2e85f238-4c98-4f25-aaf6-265171041e5e: completed, 2 matched, 1 unmatched
uploaded upload_3ef38722-b295-4925-a289-f69b8b91c293 with 1 line(s); run it with Reconciliation.Run