From 370ca1da1f018cca9c994a37342503523e874e02 Mon Sep 17 00:00:00 2001
From: mohammad mahdi rezaei <rezaei_21@yahoo.com>
Date: Sun, 17 Dec 2023 16:33:01 +0330
Subject: [PATCH] feat(niki): add logger

---
 .gitignore            |  3 +-
 go.mod                |  2 +
 go.sum                |  2 +
 logger/logger.go      | 58 ++++++++++++++++++++++++++
 logger/logger_test.go | 97 +++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 160 insertions(+), 2 deletions(-)
 create mode 100644 go.sum
 create mode 100644 logger/logger.go
 create mode 100644 logger/logger_test.go

diff --git a/.gitignore b/.gitignore
index 09ec337..c841ccc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -23,5 +23,4 @@ bin
 #env
 *.env
 
-
-
+logs/
diff --git a/go.mod b/go.mod
index ea6120e..dcf26ac 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,5 @@
 module git.gocasts.ir/ebhomengo/niki
 
 go 1.21.3
+
+require gopkg.in/natefinch/lumberjack.v2 v2.2.1
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..96b0a10
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,2 @@
+gopkg.in/natefinch/lumberjack.v2 v2.2.1 h1:bBRl1b0OH9s/DuPhuXpNl+VtCaJXFZ5/uEFST95x9zc=
+gopkg.in/natefinch/lumberjack.v2 v2.2.1/go.mod h1:YD8tP3GAjkrDg1eZH7EGmyESg/lsYskCTPBJVb9jqSc=
diff --git a/logger/logger.go b/logger/logger.go
new file mode 100644
index 0000000..b9a1288
--- /dev/null
+++ b/logger/logger.go
@@ -0,0 +1,58 @@
+package logger
+
+import (
+	"io"
+	"log/slog"
+	"os"
+
+	"gopkg.in/natefinch/lumberjack.v2"
+)
+
+const (
+	defaultFilePath        = "logs/logs.json"
+	defaultUseLocalTime    = false
+	defaultFileMaxSizeInMB = 10
+	defaultFileAgeInDays   = 30
+)
+
+type Config struct {
+	FilePath         string
+	UseLocalTime     bool
+	FileMaxSizeInMB  int
+	FileMaxAgeInDays int
+}
+
+var l *slog.Logger
+
+// init is default logger and Singleton that lets you ensure that a logger has only one instance, while providing a global access point to this instance.
+func init() {
+	fileWriter := &lumberjack.Logger{
+		Filename:  defaultFilePath,
+		LocalTime: defaultUseLocalTime,
+		MaxSize:   defaultFileMaxSizeInMB,
+		MaxAge:    defaultFileAgeInDays,
+	}
+	l = slog.New(
+		slog.NewJSONHandler(io.MultiWriter(fileWriter, os.Stdout), &slog.HandlerOptions{}),
+	)
+}
+
+func L() *slog.Logger {
+	return l
+}
+
+// New is constructor logger with special settings
+func New(cfg Config, opt *slog.HandlerOptions) *slog.Logger {
+	fileWriter := &lumberjack.Logger{
+		Filename:  cfg.FilePath,
+		LocalTime: cfg.UseLocalTime,
+		MaxSize:   cfg.FileMaxSizeInMB,
+		MaxAge:    cfg.FileMaxAgeInDays,
+	}
+
+	logger := slog.New(
+		slog.NewJSONHandler(io.MultiWriter(fileWriter, os.Stdout), opt),
+	)
+
+	return logger
+}
diff --git a/logger/logger_test.go b/logger/logger_test.go
new file mode 100644
index 0000000..9b4dac0
--- /dev/null
+++ b/logger/logger_test.go
@@ -0,0 +1,97 @@
+package logger_test
+
+import (
+	"bufio"
+	"fmt"
+	"log/slog"
+	"os"
+	"strconv"
+	"testing"
+
+	"git.gocasts.ir/ebhomengo/niki/logger"
+)
+
+func TestLogger(t *testing.T) {
+	cfg := logger.Config{
+		FilePath:         "./logs.json",
+		UseLocalTime:     false,
+		FileMaxSizeInMB:  10,
+		FileMaxAgeInDays: 1,
+	}
+	opt := slog.HandlerOptions{
+		ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
+			if a.Key == slog.TimeKey {
+				// remove time because it makes test wrong `time is so fast :)`
+				return slog.Attr{}
+			}
+
+			return a
+		},
+	}
+
+	l := logger.New(cfg, &opt)
+	tests := []struct {
+		f    func()
+		want string
+	}{
+		{
+			f: func() {
+				l.Info("INFO", "key", "value")
+			},
+			want: `{"level":"INFO","msg":"INFO","key":"value"}`,
+		},
+		{
+			f: func() {
+				l.Warn("WARN", "key", "value")
+			},
+			want: `{"level":"WARN","msg":"WARN","key":"value"}`,
+		},
+		{
+			f: func() {
+				l.Error("ERROR", "key", "value")
+			},
+			want: `{"level":"ERROR","msg":"ERROR","key":"value"}`,
+		},
+		{
+			f: func() {
+				l.With(
+					slog.Group("user",
+						slog.String("id", "user-123"),
+					),
+				).
+					With("environment", "dev").
+					With("error", fmt.Errorf("an error")).
+					Error("A message")
+			},
+			want: `{"level":"ERROR","msg":"A message","user":{"id":"user-123"},"environment":"dev","error":"an error"}`,
+		},
+	}
+
+	// first run logs
+	for _, test := range tests {
+		test.f()
+	}
+
+	f, err := os.Open(cfg.FilePath)
+	defer f.Close()
+	defer os.Remove(cfg.FilePath)
+	if err != nil {
+		t.Fatalf("can't open file: %s", err)
+	}
+
+	scanner := bufio.NewScanner(f)
+
+	var logs []string
+
+	for scanner.Scan() {
+		logs = append(logs, scanner.Text())
+	}
+
+	for i, test := range tests {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			if test.want != logs[i] {
+				t.Fatalf("want: %+v, got: %+v", test.want, logs[i])
+			}
+		})
+	}
+}