package observability

import (
	"bytes"
	"io"
	"os"
	"strings"
	"testing"
)

func TestNewLogger(t *testing.T) {
	logger := NewLogger("test")
	if logger == nil {
		t.Fatal("expected non-nil logger")
	}
	if logger.prefix != "test" {
		t.Errorf("expected prefix 'test', got %s", logger.prefix)
	}
}

func TestLogger_Info(t *testing.T) {
	// Capture stderr
	oldStderr := os.Stderr
	r, w, _ := os.Pipe()
	os.Stderr = w

	logger := NewLogger("test")
	logger.Info("test message")

	w.Close()
	os.Stderr = oldStderr

	var buf bytes.Buffer
	io.Copy(&buf, r)
	output := buf.String()

	if !strings.Contains(output, "INFO") {
		t.Error("expected INFO in output")
	}
	if !strings.Contains(output, "test message") {
		t.Error("expected 'test message' in output")
	}
}

func TestLogger_Error(t *testing.T) {
	oldStderr := os.Stderr
	r, w, _ := os.Pipe()
	os.Stderr = w

	logger := NewLogger("test")
	logger.Error("error message", nil)

	w.Close()
	os.Stderr = oldStderr

	var buf bytes.Buffer
	io.Copy(&buf, r)
	output := buf.String()

	if !strings.Contains(output, "ERROR") {
		t.Error("expected ERROR in output")
	}
	if !strings.Contains(output, "error message") {
		t.Error("expected 'error message' in output")
	}
}

func TestLogger_Debug(t *testing.T) {
	oldStderr := os.Stderr
	r, w, _ := os.Pipe()
	os.Stderr = w

	logger := NewLogger("test")
	logger.Debug("debug message")

	w.Close()
	os.Stderr = oldStderr

	var buf bytes.Buffer
	io.Copy(&buf, r)
	output := buf.String()

	if !strings.Contains(output, "DEBUG") {
		t.Error("expected DEBUG in output")
	}
	if !strings.Contains(output, "debug message") {
		t.Error("expected 'debug message' in output")
	}
}

func TestLogger_WithFields(t *testing.T) {
	logger := NewLogger("test")
	fieldsLogger := logger.WithFields(map[string]any{
		"key1": "value1",
		"key2": 42,
	})

	if fieldsLogger == logger {
		t.Error("expected different logger instance")
	}
	if len(fieldsLogger.fields) != 2 {
		t.Errorf("expected 2 fields, got %d", len(fieldsLogger.fields))
	}
}

func TestLogger_Name(t *testing.T) {
	logger := NewLogger("myservice")
	if logger.prefix != "myservice" {
		t.Errorf("expected prefix 'myservice', got %s", logger.prefix)
	}
}