package logging

import (
	"context"
	"encoding/json"
	"io"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"strings"
	"sync"
	"sync/atomic"
	"testing"
	"time"
)

func TestNewShipper(t *testing.T) {
	tests := []struct {
		name    string
		cfg     ShipperConfig
		wantErr bool
		errMsg  string
	}{
		{
			name:    "empty backend returns nil",
			cfg:     ShipperConfig{Backend: ""},
			wantErr: false,
		},
		{
			name:    "victoria backend requires URL",
			cfg:     ShipperConfig{Backend: "victoria", URL: ""},
			wantErr: true,
			errMsg:  "URL is required",
		},
		{
			name:    "victoria backend with URL succeeds",
			cfg:     ShipperConfig{Backend: "victoria", URL: "http://localhost:9428"},
			wantErr: false,
		},
		{
			name:    "unknown backend returns error",
			cfg:     ShipperConfig{Backend: "unknown"},
			wantErr: true,
			errMsg:  "unknown log shipper backend",
		},
		{
			name:    "opensearch not implemented",
			cfg:     ShipperConfig{Backend: "opensearch"},
			wantErr: true,
			errMsg:  "not yet implemented",
		},
		{
			name:    "loki not implemented",
			cfg:     ShipperConfig{Backend: "loki"},
			wantErr: true,
			errMsg:  "not yet implemented",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			shipper, err := NewShipper(tt.cfg)
			if tt.wantErr {
				if err == nil {
					t.Errorf("NewShipper() expected error, got nil")
				} else if tt.errMsg != "" && !strings.Contains(err.Error(), tt.errMsg) {
					t.Errorf("NewShipper() error = %v, want error containing %q", err, tt.errMsg)
				}
				return
			}
			if err != nil {
				t.Errorf("NewShipper() unexpected error: %v", err)
			}
			if tt.cfg.Backend == "" && shipper != nil {
				t.Error("NewShipper() with empty backend should return nil shipper")
			}
			if shipper != nil {
				shipper.Close()
			}
		})
	}
}

func TestVictoriaShipper_Ship(t *testing.T) {
	var receivedLogs []map[string]any
	var mu sync.Mutex

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			t.Errorf("expected POST, got %s", r.Method)
		}
		if !strings.Contains(r.URL.Path, "/insert/jsonline") {
			t.Errorf("expected /insert/jsonline path, got %s", r.URL.Path)
		}
		if r.Header.Get("Content-Type") != "application/stream+json" {
			t.Errorf("expected application/stream+json content type, got %s", r.Header.Get("Content-Type"))
		}

		body, _ := io.ReadAll(r.Body)
		lines := strings.Split(strings.TrimSpace(string(body)), "\n")

		mu.Lock()
		for _, line := range lines {
			var doc map[string]any
			if err := json.Unmarshal([]byte(line), &doc); err != nil {
				t.Errorf("failed to unmarshal log line: %v", err)
			}
			receivedLogs = append(receivedLogs, doc)
		}
		mu.Unlock()

		w.WriteHeader(http.StatusOK)
	}))
	defer server.Close()

	shipper, err := NewVictoriaShipper(ShipperConfig{
		URL:     server.URL,
		Service: "test-service",
	})
	if err != nil {
		t.Fatalf("NewVictoriaShipper() error: %v", err)
	}
	defer shipper.Close()

	entries := []LogEntry{
		{
			Time:    time.Date(2024, 1, 8, 12, 0, 0, 0, time.UTC),
			Level:   slog.LevelInfo,
			Message: "test message 1",
			Source:  "test.go:42",
			Attrs:   map[string]any{"key1": "value1"},
		},
		{
			Time:    time.Date(2024, 1, 8, 12, 0, 1, 0, time.UTC),
			Level:   slog.LevelError,
			Message: "test message 2",
			Source:  "test.go:43",
			Attrs:   map[string]any{"key2": 123},
		},
	}

	ctx := context.Background()
	if err := shipper.Ship(ctx, entries); err != nil {
		t.Fatalf("Ship() error: %v", err)
	}

	mu.Lock()
	defer mu.Unlock()

	if len(receivedLogs) != 2 {
		t.Errorf("expected 2 logs, got %d", len(receivedLogs))
	}

	// Check first log
	if receivedLogs[0]["_msg"] != "test message 1" {
		t.Errorf("expected _msg 'test message 1', got %v", receivedLogs[0]["_msg"])
	}
	if receivedLogs[0]["level"] != "INFO" {
		t.Errorf("expected level 'INFO', got %v", receivedLogs[0]["level"])
	}
	if receivedLogs[0]["service"] != "test-service" {
		t.Errorf("expected service 'test-service', got %v", receivedLogs[0]["service"])
	}
	if receivedLogs[0]["key1"] != "value1" {
		t.Errorf("expected key1 'value1', got %v", receivedLogs[0]["key1"])
	}

	// Check second log
	if receivedLogs[1]["level"] != "ERROR" {
		t.Errorf("expected level 'ERROR', got %v", receivedLogs[1]["level"])
	}
}

func TestVictoriaShipper_BasicAuth(t *testing.T) {
	var authHeader string

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		authHeader = r.Header.Get("Authorization")
		w.WriteHeader(http.StatusOK)
	}))
	defer server.Close()

	shipper, err := NewVictoriaShipper(ShipperConfig{
		URL:      server.URL,
		Username: "testuser",
		Password: "testpass",
	})
	if err != nil {
		t.Fatalf("NewVictoriaShipper() error: %v", err)
	}
	defer shipper.Close()

	entries := []LogEntry{{Time: time.Now(), Level: slog.LevelInfo, Message: "test"}}
	if err := shipper.Ship(context.Background(), entries); err != nil {
		t.Fatalf("Ship() error: %v", err)
	}

	if authHeader == "" {
		t.Error("expected Authorization header to be set")
	}
	if !strings.HasPrefix(authHeader, "Basic ") {
		t.Errorf("expected Basic auth, got: %s", authHeader)
	}
}

func TestVictoriaShipper_EmptyBatch(t *testing.T) {
	var called bool

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		called = true
		w.WriteHeader(http.StatusOK)
	}))
	defer server.Close()

	shipper, _ := NewVictoriaShipper(ShipperConfig{URL: server.URL})
	defer shipper.Close()

	if err := shipper.Ship(context.Background(), nil); err != nil {
		t.Errorf("Ship() with nil entries should not error: %v", err)
	}
	if err := shipper.Ship(context.Background(), []LogEntry{}); err != nil {
		t.Errorf("Ship() with empty entries should not error: %v", err)
	}
	if called {
		t.Error("Ship() should not make HTTP request for empty batch")
	}
}

func TestVictoriaShipper_ServerError(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusInternalServerError)
		w.Write([]byte("internal error"))
	}))
	defer server.Close()

	shipper, _ := NewVictoriaShipper(ShipperConfig{URL: server.URL})
	defer shipper.Close()

	entries := []LogEntry{{Time: time.Now(), Level: slog.LevelInfo, Message: "test"}}
	err := shipper.Ship(context.Background(), entries)
	if err == nil {
		t.Error("Ship() should return error on server error")
	}
	if !strings.Contains(err.Error(), "500") {
		t.Errorf("error should contain status code, got: %v", err)
	}
}

func TestAsyncHandler_Batching(t *testing.T) {
	var shipCount atomic.Int32
	var totalEntries atomic.Int32

	mockShipper := &mockShipper{
		shipFunc: func(ctx context.Context, entries []LogEntry) error {
			shipCount.Add(1)
			totalEntries.Add(int32(len(entries)))
			return nil
		},
	}

	cfg := ShipperConfig{
		BatchSize:     5,
		FlushInterval: 100 * time.Millisecond,
	}

	stdoutHandler := slog.NewTextHandler(io.Discard, nil)
	handler := NewAsyncHandler(stdoutHandler, mockShipper, cfg, nil)

	// Log 12 entries - should trigger 2 batch flushes (at 5 and 10) plus 2 remaining
	for range 12 {
		record := slog.NewRecord(time.Now(), slog.LevelInfo, "test message", 0)
		handler.Handle(context.Background(), record)
	}

	// Wait for flush interval to trigger
	time.Sleep(200 * time.Millisecond)

	handler.Shutdown()

	if totalEntries.Load() != 12 {
		t.Errorf("expected 12 total entries shipped, got %d", totalEntries.Load())
	}
}

func TestAsyncHandler_Shutdown(t *testing.T) {
	var shipped []LogEntry
	var mu sync.Mutex

	mockShipper := &mockShipper{
		shipFunc: func(ctx context.Context, entries []LogEntry) error {
			mu.Lock()
			shipped = append(shipped, entries...)
			mu.Unlock()
			return nil
		},
	}

	cfg := ShipperConfig{
		BatchSize:     100, // Large batch size so nothing flushes immediately
		FlushInterval: 10 * time.Second,
	}

	stdoutHandler := slog.NewTextHandler(io.Discard, nil)
	handler := NewAsyncHandler(stdoutHandler, mockShipper, cfg, nil)

	// Log a few entries
	for range 3 {
		record := slog.NewRecord(time.Now(), slog.LevelInfo, "test", 0)
		handler.Handle(context.Background(), record)
	}

	// Entries should be pending (not shipped yet due to large batch size)
	mu.Lock()
	if len(shipped) != 0 {
		t.Errorf("expected 0 shipped before shutdown, got %d", len(shipped))
	}
	mu.Unlock()

	// Shutdown should flush pending entries
	handler.Shutdown()

	mu.Lock()
	if len(shipped) != 3 {
		t.Errorf("expected 3 shipped after shutdown, got %d", len(shipped))
	}
	mu.Unlock()
}

func TestAsyncHandler_NoShipper(t *testing.T) {
	cfg := ShipperConfig{}
	stdoutHandler := slog.NewTextHandler(io.Discard, nil)
	handler := NewAsyncHandler(stdoutHandler, nil, cfg, nil)

	// Should not panic with nil shipper
	record := slog.NewRecord(time.Now(), slog.LevelInfo, "test", 0)
	if err := handler.Handle(context.Background(), record); err != nil {
		t.Errorf("Handle() with nil shipper should not error: %v", err)
	}

	// Shutdown should not panic
	handler.Shutdown()
}

func TestResolveAttrValue(t *testing.T) {
	tests := []struct {
		name     string
		value    slog.Value
		expected any
	}{
		{"string", slog.StringValue("test"), "test"},
		{"int64", slog.Int64Value(42), int64(42)},
		{"uint64", slog.Uint64Value(42), uint64(42)},
		{"float64", slog.Float64Value(3.14), 3.14},
		{"bool", slog.BoolValue(true), true},
		{"duration", slog.DurationValue(5 * time.Second), "5s"},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got := resolveAttrValue(tt.value)
			if got != tt.expected {
				t.Errorf("resolveAttrValue() = %v, want %v", got, tt.expected)
			}
		})
	}
}

// mockShipper implements Shipper for testing
type mockShipper struct {
	shipFunc  func(ctx context.Context, entries []LogEntry) error
	closeFunc func() error
}

func (m *mockShipper) Ship(ctx context.Context, entries []LogEntry) error {
	if m.shipFunc != nil {
		return m.shipFunc(ctx, entries)
	}
	return nil
}

func (m *mockShipper) Close() error {
	if m.closeFunc != nil {
		return m.closeFunc()
	}
	return nil
}