implement reporter

also introduce gomock and tests

main.go

@@ -1,12 +1,8 @@
 package main
 
 import (
-	"container/list"
-	"errors"
 	"fmt"
-	"io"
 	"log/slog"
-	"math/big"
 	"os"
 
 	"git.naterciomoniz.net/applications/broker2anexoj/internal"
@@ -26,72 +22,16 @@ func run() error {
 		return fmt.Errorf("open statement: %w", err)
 	}
 
-	r := trading212.NewRecordReader(f)
+	reader := trading212.NewRecordReader(f)
 
-	assets := make(map[string]*list.List)
-	for {
-		record, err := r.ReadRecord()
-		if err != nil {
-			if errors.Is(err, io.EOF) {
-				break
-			}
-			return fmt.Errorf("read statement record: %w", err)
-		}
+	reporter := internal.NewReporter(reader)
 
-		switch record.Side() {
-		case internal.SideBuy:
-			lst, ok := assets[record.Symbol()]
-			if !ok {
-				lst = list.New()
-				assets[record.Symbol()] = lst
-			}
-			lst.PushBack(record)
-
-		case internal.SideSell:
-			lst, ok := assets[record.Symbol()]
-			if !ok {
-				return ErrSellWithoutBuy
-			}
-
-			unmatchedQty := new(big.Float).Copy(record.Quantity())
-			zero := new(big.Float)
-
-			for unmatchedQty.Cmp(zero) > 0 {
-				front := lst.Front()
-				if front == nil {
-					return ErrSellWithoutBuy
-				}
-
-				next, ok := front.Value.(internal.Record)
-				if !ok {
-					return fmt.Errorf("unexpected record type: %T", front)
-				}
-
-				var matchedQty *big.Float
-				if next.Quantity().Cmp(unmatchedQty) > 0 {
-					matchedQty = unmatchedQty
-					next.Quantity().Sub(next.Quantity(), unmatchedQty)
-				} else {
-					matchedQty = next.Quantity()
-					lst.Remove(front)
-				}
-
-				unmatchedQty.Sub(unmatchedQty, matchedQty)
-
-				sellValue := new(big.Float).Mul(matchedQty, record.Price())
-				buyValue := new(big.Float).Mul(matchedQty, next.Price())
-				realisedPnL := new(big.Float).Sub(sellValue, buyValue)
-				slog.Info("Realised PnL",
-					slog.Any("Symbol", record.Symbol()),
-					slog.Any("PnL", realisedPnL))
-			}
-
-		default:
-			return fmt.Errorf("unknown side: %s", record.Side())
-		}
+	err = reporter.Run()
+	if err != nil {
+		return err
 	}
 
-	slog.Info("Finish processing statement", slog.Any("assets_count", len(assets)))
+	slog.Info("Finish processing statement")
 
 	return nil
 }