Minor improvements

generators.go

@@ -39,13 +39,7 @@ func (self ReportGeneratorNaive) Generate(fp *os.File) (Report, error) {
 
 	report := make(Report)
 	for i := 0; i < len(transactions); i++ {
-		transaction := transactions[i]
-		if report[transaction.UserId] == nil {
-			report[transaction.UserId] = make(ReportRow)
-		}
-		report[transaction.UserId]["sum"] += transaction.Amount
-		report[transaction.UserId]["user_id"] = transaction.UserId
-		report[transaction.UserId]["category_"+transaction.Category] += transaction.Amount
+		report.Update(transactions[i])
 	}
 
 	return report, nil
@@ -76,14 +70,7 @@ func (self ReportGeneratorStream) Generate(fp *os.File) (Report, error) {
 		if err != nil {
 			return nil, err
 		}
-
-		if report[transaction.UserId] == nil {
-			report[transaction.UserId] = make(ReportRow)
-		}
-
-		report[transaction.UserId]["sum"] += transaction.Amount
-		report[transaction.UserId]["user_id"] = transaction.UserId
-		report[transaction.UserId]["category_"+transaction.Category] += transaction.Amount
+		report.Update(transaction)
 	}
 
 	token, err = decoder.Token()

input/README.md

@@ -0,0 +1,3 @@
+Обычно файлы с данными не коммитят в репозиторий, но во имя самодостаточности
+и для сохранения истории, я всё же оставлю один наглядный пример JSON'а, парсинг
+которого реализован в данной задаче.

main.go

@@ -24,13 +24,22 @@ type Transaction struct {
 	Category string `json:"category"`
 }
 
+func (self Report) Update(transaction Transaction) {
+	if self[transaction.UserId] == nil {
+		self[transaction.UserId] = make(ReportRow)
+	}
+	self[transaction.UserId]["sum"] += transaction.Amount
+	self[transaction.UserId]["user_id"] = transaction.UserId
+	self[transaction.UserId]["category_"+transaction.Category] += transaction.Amount
+}
+
 // -----------------------------------------------------------------------------
 // Utils
 // -----------------------------------------------------------------------------
 var start = time.Now()
 var helpArg = flag.Bool("h", false, "Print help and exit")
 var algoArg = flag.String("a", "naive", "Algorithm to use: naive, stream")
-var inputArg = flag.String("i", "input/10M.json", "Path to the input file")
+var inputArg = flag.String("i", "input/10K_transactions.json", "Path to the input file")
 var outputArg = flag.String("o", "output/report.json", "Path to the output file")
 var formatArg = flag.String("f", "json", "Report format: json, csv, sqlite")
 var quietArg = flag.Bool("q", false, "Disable logs output")

main_test.go

@@ -22,3 +22,90 @@ func TestResolvePath(t *testing.T) {
 		t.Fatalf("absolute path resolve was incorrect")
 	}
 }
+
+func TestReportUpdateGroupByCategory(t *testing.T) {
+	report := make(Report)
+
+	report.Update(Transaction{UserId: 10, Amount: 10, Category: "aa"})
+	report.Update(Transaction{UserId: 10, Amount: 20, Category: "aa"})
+	report.Update(Transaction{UserId: 10, Amount: 40, Category: "bb"})
+
+	if len(report) != 1 {
+		t.Fatalf("unexpected report length")
+	}
+
+	if report[10]["user_id"] != 10 {
+		t.Fatalf("user_id was set incorrect")
+	}
+
+	if report[10]["sum"] != 70 {
+		t.Fatalf("sum was set incorrect")
+	}
+
+	if report[10]["category_aa"] != 30 {
+		t.Fatalf("category_aa was set incorrect")
+	}
+
+	if report[10]["category_bb"] != 40 {
+		t.Fatalf("category_bb was set incorrect")
+	}
+}
+
+func TestReportUpdateGroupByUser(t *testing.T) {
+	report := make(Report)
+
+	report.Update(Transaction{UserId: 10, Amount: 10, Category: "aa"})
+	report.Update(Transaction{UserId: 10, Amount: 20, Category: "aa"})
+	report.Update(Transaction{UserId: 11, Amount: 30, Category: "bb"})
+	report.Update(Transaction{UserId: 11, Amount: 40, Category: "bb"})
+
+	if len(report) != 2 {
+		t.Fatalf("unexpected report length")
+	}
+
+	if report[10]["user_id"] != 10 {
+		t.Fatalf("user_id was set incorrect")
+	}
+
+	if report[10]["sum"] != 30 {
+		t.Fatalf("sum was set incorrect")
+	}
+
+	if report[10]["category_aa"] != 30 {
+		t.Fatalf("category_aa was set incorrect")
+	}
+
+	if report[11]["user_id"] != 11 {
+		t.Fatalf("user_id was set incorrect")
+	}
+
+	if report[11]["sum"] != 70 {
+		t.Fatalf("sum was set incorrect")
+	}
+
+	if report[11]["category_bb"] != 70 {
+		t.Fatalf("category_aa was set incorrect")
+	}
+}
+
+func TestReportUpdateGroupEmptyCategory(t *testing.T) {
+	report := make(Report)
+
+	report.Update(Transaction{UserId: 10, Amount: 10})
+
+	if len(report) != 1 {
+		t.Fatalf("unexpected report length")
+	}
+
+	if report[10]["user_id"] != 10 {
+		t.Fatalf("user_id was set incorrect")
+	}
+
+	if report[10]["sum"] != 10 {
+		t.Fatalf("sum was set incorrect")
+	}
+
+	if report[10]["category_"] != 10 {
+		t.Fatalf("category_ was set incorrect")
+	}
+}

writers.go

@@ -92,6 +92,8 @@ type ReportWriterSQLite struct {
 }
 
 func (self ReportWriterSQLite) Write(report Report, outputPath string) error {
+	os.Remove(outputPath)
+
 	db, err := sql.Open("sqlite3", outputPath)
 
 	if err != nil {
@@ -101,10 +103,6 @@ func (self ReportWriterSQLite) Write(report Report, outputPath string) error {
 	defer db.Close()
 
 	_, err = db.Exec(`
-		DROP TABLE IF EXISTS users_report;
-
-		DROP TABLE IF EXISTS users_categories_report;
-
 		CREATE TABLE users_report (
 			id INT NOT NULL,
 			sum INT NOT NULL,