logger/logger_test.go

package logger

import (
	"bytes"
	"encoding/json"
	"path/filepath"
	"strings"
	"testing"

	"github.com/korap/korap-mcp/config"
	"github.com/rs/zerolog"
	"github.com/stretchr/testify/assert"
)

func TestSetupLogger(t *testing.T) {
	t.Run("should setup logger with default configuration", func(t *testing.T) {
		cfg := &config.LoggingConfig{
			Level:  "info",
			Format: "json",
		}

		logger, err := SetupLogger(cfg)
		assert.NoError(t, err)
		assert.NotNil(t, logger)
	})

	t.Run("should setup logger with text format", func(t *testing.T) {
		cfg := &config.LoggingConfig{
			Level:  "debug",
			Format: "text",
		}

		logger, err := SetupLogger(cfg)
		assert.NoError(t, err)
		assert.NotNil(t, logger)
	})

	t.Run("should setup logger with file output", func(t *testing.T) {
		// Create temporary file
		tmpDir := t.TempDir()
		logFile := filepath.Join(tmpDir, "test.log")

		cfg := &config.LoggingConfig{
			Level:  "warn",
			Format: "json",
			File:   logFile,
		}

		logger, err := SetupLogger(cfg)
		assert.NoError(t, err)
		assert.NotNil(t, logger)

		// Test logging to file
		logger.Info().Msg("test message")

		// Verify file was created
		assert.FileExists(t, logFile)
	})

	t.Run("should return error for invalid log level", func(t *testing.T) {
		cfg := &config.LoggingConfig{
			Level:  "invalid",
			Format: "json",
		}

		_, err := SetupLogger(cfg)
		assert.Error(t, err)
		assert.Contains(t, strings.ToLower(err.Error()), "unknown level")
	})

	t.Run("should return error for invalid file path", func(t *testing.T) {
		cfg := &config.LoggingConfig{
			Level:  "info",
			Format: "json",
			File:   "/invalid/path/test.log",
		}

		_, err := SetupLogger(cfg)
		assert.Error(t, err)
	})
}

func TestGetLogger(t *testing.T) {
	t.Run("should return configured logger", func(t *testing.T) {
		cfg := &config.LoggingConfig{
			Level:  "debug",
			Format: "json",
		}

		logger := GetLogger(cfg)
		assert.NotNil(t, logger)
	})

	t.Run("should return fallback logger on configuration error", func(t *testing.T) {
		cfg := &config.LoggingConfig{
			Level:  "invalid",
			Format: "json",
		}

		logger := GetLogger(cfg)
		assert.NotNil(t, logger)
	})
}

func TestLoggerOutput(t *testing.T) {
	t.Run("should produce structured JSON output", func(t *testing.T) {
		var buf bytes.Buffer

		// Create a logger that writes to our buffer
		logger := zerolog.New(&buf).With().Timestamp().Logger()

		// Log a message
		logger.Info().Str("test", "value").Msg("test message")

		// Parse the JSON output
		var logEntry map[string]any
		err := json.Unmarshal(buf.Bytes(), &logEntry)
		assert.NoError(t, err)

		// Verify log structure
		assert.Equal(t, "info", logEntry["level"])
		assert.Equal(t, "test message", logEntry["message"])
		assert.Equal(t, "value", logEntry["test"])
		assert.Contains(t, logEntry, "time")
	})

	t.Run("should respect log levels", func(t *testing.T) {
		var buf bytes.Buffer

		// Set global level to warn
		zerolog.SetGlobalLevel(zerolog.WarnLevel)
		logger := zerolog.New(&buf).With().Timestamp().Logger()

		// Try to log at different levels
		logger.Debug().Msg("debug message")
		logger.Info().Msg("info message")
		logger.Warn().Msg("warn message")

		// Only warn message should be present
		output := buf.String()
		assert.NotContains(t, output, "debug message")
		assert.NotContains(t, output, "info message")
		assert.Contains(t, output, "warn message")

		// Reset global level
		zerolog.SetGlobalLevel(zerolog.InfoLevel)
	})
}

func TestLoggerIntegration(t *testing.T) {
	t.Run("should work with all supported log levels", func(t *testing.T) {
		levels := []string{"trace", "debug", "info", "warn", "error", "fatal", "panic"}

		for _, level := range levels {
			cfg := &config.LoggingConfig{
				Level:  level,
				Format: "json",
			}

			logger, err := SetupLogger(cfg)
			if level == "panic" {
				// panic level might not be supported in all contexts
				continue
			}
			assert.NoError(t, err, "Failed to setup logger with level: %s", level)
			assert.NotNil(t, logger, "Logger should not be nil for level: %s", level)
		}
	})

	t.Run("should work with different output formats", func(t *testing.T) {
		formats := []string{"json", "text"}

		for _, format := range formats {
			cfg := &config.LoggingConfig{
				Level:  "info",
				Format: format,
			}

			logger, err := SetupLogger(cfg)
			assert.NoError(t, err, "Failed to setup logger with format: %s", format)
			assert.NotNil(t, logger, "Logger should not be nil for format: %s", format)
		}
	})
}

func TestLoggerErrorHandling(t *testing.T) {
	t.Run("should handle errors gracefully in GetLogger", func(t *testing.T) {
		// Test with various invalid configurations
		invalidConfigs := []*config.LoggingConfig{
			{Level: "invalid-level", Format: "json"},
			{Level: "info", Format: "json", File: "/dev/null/invalid"},
		}

		for _, cfg := range invalidConfigs {
			logger := GetLogger(cfg)
			// Should not panic and should return a valid logger
			assert.NotNil(t, logger)

			// Should be able to log
			logger.Info().Msg("test message")
		}
	})
}