implement analyzer.go:Analyzer:LargestTransaction to return the first largest transaction in slice

digits-work-sample-go.d/analyzer.go

@@ -1,7 +1,5 @@
 package analyzer
 
-import "errors"
-
 // Analyzer processes Transactions and generates reports.
 type Analyzer struct {
 	// The list of Transactions available to analyze.
@@ -28,11 +26,19 @@ func (anz *Analyzer) TransactionsAmount() Amount {
 // the absolute value of the transaction amount. Returns an error if there
 // are no transactions.
 //
-// - Note: Large negative transactions are still large--it just means the
-//         money moved the other direction.
+//   - Note: Large negative transactions are still large--it just means the
+//     money moved the other direction.
 func (anz *Analyzer) LargestTransaction() (Transaction, error) {
-	// TODO: Not implemented.
-	return Transaction{}, errors.New("not implemented")
+	if anz == nil || len(anz.transactions) == 0 {
+		return Transaction{}, ErrNoTransactionsToAnalyze
+	}
+	largestIdx := 0
+	for i := 1; i < len(anz.transactions); i++ {
+		if anz.transactions[largestIdx].Amount.AbsoluteValue() < anz.transactions[i].Amount.AbsoluteValue() {
+			largestIdx = i
+		}
+	}
+	return anz.transactions[largestIdx], nil
 }
 
 // ByCategory groups the transactions by category and returns a map of

digits-work-sample-go.d/errors.go

@@ -0,0 +1,7 @@
+package analyzer
+
+import "errors"
+
+var (
+	ErrNoTransactionsToAnalyze = errors.New("no transactions to analyze")
+)

todo.yaml

@@ -2,7 +2,6 @@ todo:
 - review readme tail to finish // answer 3 questions, gofmt
 - todo: go test
   subtasks:
-  - TestAnalyzer_LargestTransaction
   - TestAnalyzer_DuplicatesExcluded
   - TestAnalyzer_GroupByCategory
   - TestAnalyzer_BigSpendersReport
@@ -16,6 +15,8 @@ todo:
     not be changed, or even what currency Amount is
   - transaction.go:Transaction:Sum again doesnt care about Amount currency or vendor/vendee
     drift
+  - analyzer.go:Analyzer:LargestTransaction doesn't specify how to break ties; stable
+    or latest?
 scheduled: []
 done:
 - todo: hello world
@@ -451,3 +452,39 @@ done:
   - transaction.go:Transaction:Sum again doesnt care about Amount currency or vendor/vendee
     drift
   ts: Sun Oct 15 11:36:45 MDT 2023
+- todo: go test
+  subtasks:
+  - TestAnalyzer_LargestTransaction
+  - TestAnalyzer_DuplicatesExcluded
+  - TestAnalyzer_GroupByCategory
+  - TestAnalyzer_BigSpendersReport
+  - TestAnalyzer_TransactionsFromURLs
+  - TestAnalyzer_TransactionsFromURLsConcurrent
+  - amount.go:Rounded probably does NOT handle float precision well... it is float64
+    tho...
+  - my `go mod tidy` actually cleared `go.mod` file, probably weird localhost backwards
+    compatilble stuff
+  - transaction.go:Transaction:String not clear if FormatUSD or amount currency should
+    not be changed, or even what currency Amount is
+  - transaction.go:Transaction:Sum again doesnt care about Amount currency or vendor/vendee
+    drift
+  ts: Sun Oct 15 11:38:22 MDT 2023
+- todo: go test
+  subtasks:
+  - TestAnalyzer_LargestTransaction
+  - TestAnalyzer_DuplicatesExcluded
+  - TestAnalyzer_GroupByCategory
+  - TestAnalyzer_BigSpendersReport
+  - TestAnalyzer_TransactionsFromURLs
+  - TestAnalyzer_TransactionsFromURLsConcurrent
+  - amount.go:Rounded probably does NOT handle float precision well... it is float64
+    tho...
+  - my `go mod tidy` actually cleared `go.mod` file, probably weird localhost backwards
+    compatilble stuff
+  - transaction.go:Transaction:String not clear if FormatUSD or amount currency should
+    not be changed, or even what currency Amount is
+  - transaction.go:Transaction:Sum again doesnt care about Amount currency or vendor/vendee
+    drift
+  - analyzer.go:Analyzer:LargestTransaction doesn't specify how to break ties; stable
+    or latest?
+  ts: Sun Oct 15 11:38:46 MDT 2023