package grpcclient_test

import (
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"

	"go.yandata.net/iod/iod/go-trustlog/internal/grpcclient"
)

// mockClient 用于测试的模拟客户端.
type mockClient struct {
	ID string
}

func TestNewLoadBalancer(t *testing.T) {
	tests := []struct {
		name     string
		addrs    []string
		dialOpts []grpc.DialOption
		wantErr  bool
		errMsg   string
	}{
		{
			name: "成功创建负载均衡器",
			addrs: []string{
				"localhost:9090",
				"localhost:9091",
			},
			dialOpts: []grpc.DialOption{
				grpc.WithTransportCredentials(insecure.NewCredentials()),
			},
			wantErr: false,
		},
		{
			name:     "没有地址应该失败",
			addrs:    []string{},
			dialOpts: nil,
			wantErr:  true,
			errMsg:   "at least one server address is required",
		},
		{
			name:     "nil地址列表应该失败",
			addrs:    nil,
			dialOpts: nil,
			wantErr:  true,
			errMsg:   "at least one server address is required",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			lb, err := grpcclient.NewLoadBalancer(
				tt.addrs,
				tt.dialOpts,
				func(_ grpc.ClientConnInterface) *mockClient {
					return &mockClient{ID: "test"}
				},
			)

			if tt.wantErr {
				require.Error(t, err)
				if tt.errMsg != "" {
					assert.Contains(t, err.Error(), tt.errMsg)
				}
				assert.Nil(t, lb)
			} else {
				// 注意：这里会实际尝试连接，在测试环境下可能失败
				// 实际使用时应该使用 mock 或 bufconn
				if err != nil {
					t.Skipf("Skipping test - cannot connect to servers: %v", err)
					return
				}
				require.NoError(t, err)
				require.NotNil(t, lb)
				assert.Equal(t, len(tt.addrs), lb.ServerCount())
				// 清理
				_ = lb.Close()
			}
		})
	}
}

func TestLoadBalancer_Next(t *testing.T) {
	// 创建一个模拟的负载均衡器，不需要真实连接
	t.Run("轮询算法测试", func(t *testing.T) {
		// 这个测试需要使用 bufconn 或其他 mock 方式
		// 暂时跳过需要真实连接的测试
		if testing.Short() {
			t.Skip("Skipping test that requires network connection")
		}

		addrs := []string{"localhost:9090", "localhost:9091", "localhost:9092"}
		lb, err := grpcclient.NewLoadBalancer(
			addrs,
			[]grpc.DialOption{grpc.WithTransportCredentials(insecure.NewCredentials())},
			func(_ grpc.ClientConnInterface) *mockClient {
				return &mockClient{ID: "test"}
			},
		)
		if err != nil {
			t.Skipf("Cannot create load balancer: %v", err)
			return
		}
		defer lb.Close()

		// 测试轮询：调用 Next() 多次应该轮询返回不同的客户端
		clients := make([]*mockClient, 6)
		for i := range 6 {
			clients[i] = lb.Next()
			assert.NotNil(t, clients[i])
		}
	})
}

func TestLoadBalancer_Close(t *testing.T) {
	if testing.Short() {
		t.Skip("Skipping test that requires network connection")
	}

	addrs := []string{"localhost:9090"}
	lb, err := grpcclient.NewLoadBalancer(
		addrs,
		[]grpc.DialOption{grpc.WithTransportCredentials(insecure.NewCredentials())},
		func(_ grpc.ClientConnInterface) *mockClient {
			return &mockClient{ID: "test"}
		},
	)
	if err != nil {
		t.Skipf("Cannot create load balancer: %v", err)
		return
	}

	// 第一次关闭
	err = lb.Close()
	require.NoError(t, err)

	// 再次关闭应该也不会报错
	err = lb.Close()
	assert.NoError(t, err)
}

func TestLoadBalancer_ServerCount(t *testing.T) {
	if testing.Short() {
		t.Skip("Skipping test that requires network connection")
	}

	tests := []struct {
		name      string
		addrs     []string
		wantCount int
	}{
		{
			name:      "单服务器",
			addrs:     []string{"localhost:9090"},
			wantCount: 1,
		},
		{
			name:      "多服务器",
			addrs:     []string{"localhost:9090", "localhost:9091", "localhost:9092"},
			wantCount: 3,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			lb, err := grpcclient.NewLoadBalancer(
				tt.addrs,
				[]grpc.DialOption{grpc.WithTransportCredentials(insecure.NewCredentials())},
				func(_ grpc.ClientConnInterface) *mockClient {
					return &mockClient{ID: "test"}
				},
			)
			if err != nil {
				t.Skipf("Cannot create load balancer: %v", err)
				return
			}
			defer lb.Close()

			assert.Equal(t, tt.wantCount, lb.ServerCount())
		})
	}
}