package rpc

import (
	"context"
	"crypto/tls"
	"encoding/base64"
	"errors"
	"fmt"
	"net/url"
	"sync"
	"time"

	"github.com/TeaOSLab/EdgeCommon/pkg/rpc/pb"
	"github.com/TeaOSLab/EdgeHttpDNS/internal/configs"
	teaconst "github.com/TeaOSLab/EdgeHttpDNS/internal/const"
	"github.com/TeaOSLab/EdgeHttpDNS/internal/encrypt"
	"github.com/iwind/TeaGo/maps"
	"github.com/iwind/TeaGo/rands"
	"google.golang.org/grpc"
	"google.golang.org/grpc/connectivity"
	"google.golang.org/grpc/credentials"
	"google.golang.org/grpc/credentials/insecure"
	"google.golang.org/grpc/encoding/gzip"
	"google.golang.org/grpc/keepalive"
	"google.golang.org/grpc/metadata"
	"sync/atomic"
)

type RPCClient struct {
	apiConfig *configs.APIConfig
	conns     []*grpc.ClientConn
	locker    sync.RWMutex

	NodeTaskRPC          pb.NodeTaskServiceClient
	NodeValueRPC         pb.NodeValueServiceClient
	HTTPDNSNodeRPC       pb.HTTPDNSNodeServiceClient
	HTTPDNSClusterRPC    pb.HTTPDNSClusterServiceClient
	HTTPDNSAppRPC        pb.HTTPDNSAppServiceClient
	HTTPDNSDomainRPC     pb.HTTPDNSDomainServiceClient
	HTTPDNSRuleRPC       pb.HTTPDNSRuleServiceClient
	HTTPDNSRuntimeLogRPC pb.HTTPDNSRuntimeLogServiceClient
	HTTPDNSAccessLogRPC  pb.HTTPDNSAccessLogServiceClient
	HTTPDNSSandboxRPC    pb.HTTPDNSSandboxServiceClient

	totalRequests  int64
	failedRequests int64
	totalCostMs    int64
}

func NewRPCClient(apiConfig *configs.APIConfig) (*RPCClient, error) {
	if apiConfig == nil {
		return nil, errors.New("api config should not be nil")
	}

	client := &RPCClient{apiConfig: apiConfig}
	client.NodeTaskRPC = pb.NewNodeTaskServiceClient(client)
	client.NodeValueRPC = pb.NewNodeValueServiceClient(client)
	client.HTTPDNSNodeRPC = pb.NewHTTPDNSNodeServiceClient(client)
	client.HTTPDNSClusterRPC = pb.NewHTTPDNSClusterServiceClient(client)
	client.HTTPDNSAppRPC = pb.NewHTTPDNSAppServiceClient(client)
	client.HTTPDNSDomainRPC = pb.NewHTTPDNSDomainServiceClient(client)
	client.HTTPDNSRuleRPC = pb.NewHTTPDNSRuleServiceClient(client)
	client.HTTPDNSRuntimeLogRPC = pb.NewHTTPDNSRuntimeLogServiceClient(client)
	client.HTTPDNSAccessLogRPC = pb.NewHTTPDNSAccessLogServiceClient(client)
	client.HTTPDNSSandboxRPC = pb.NewHTTPDNSSandboxServiceClient(client)

	err := client.init()
	if err != nil {
		return nil, err
	}
	return client, nil
}

func (c *RPCClient) Context() context.Context {
	ctx := context.Background()
	payload := maps.Map{
		"timestamp": time.Now().Unix(),
		"type":      "httpdns",
		"userId":    0,
	}

	method, err := encrypt.NewMethodInstance(teaconst.EncryptMethod, c.apiConfig.Secret, c.apiConfig.NodeId)
	if err != nil {
		return context.Background()
	}
	encrypted, err := method.Encrypt(payload.AsJSON())
	if err != nil {
		return context.Background()
	}

	token := base64.StdEncoding.EncodeToString(encrypted)
	return metadata.AppendToOutgoingContext(ctx, "nodeId", c.apiConfig.NodeId, "token", token)
}

func (c *RPCClient) UpdateConfig(config *configs.APIConfig) error {
	c.apiConfig = config
	c.locker.Lock()
	defer c.locker.Unlock()
	return c.init()
}

func (c *RPCClient) init() error {
	conns := []*grpc.ClientConn{}
	for _, endpoint := range c.apiConfig.RPCEndpoints {
		u, err := url.Parse(endpoint)
		if err != nil {
			return fmt.Errorf("parse endpoint failed: %w", err)
		}

		var conn *grpc.ClientConn
		callOptions := grpc.WithDefaultCallOptions(
			grpc.MaxCallRecvMsgSize(128<<20),
			grpc.MaxCallSendMsgSize(128<<20),
			grpc.UseCompressor(gzip.Name),
		)
		keepaliveParams := grpc.WithKeepaliveParams(keepalive.ClientParameters{
			Time: 30 * time.Second,
		})

		if u.Scheme == "http" {
			conn, err = grpc.Dial(u.Host, grpc.WithTransportCredentials(insecure.NewCredentials()), callOptions, keepaliveParams)
		} else if u.Scheme == "https" {
			conn, err = grpc.Dial(u.Host, grpc.WithTransportCredentials(credentials.NewTLS(&tls.Config{
				InsecureSkipVerify: true,
			})), callOptions, keepaliveParams)
		} else {
			return errors.New("invalid endpoint scheme '" + u.Scheme + "'")
		}
		if err != nil {
			return err
		}
		conns = append(conns, conn)
	}

	if len(conns) == 0 {
		return errors.New("no available rpc endpoints")
	}

	c.conns = conns
	return nil
}

func (c *RPCClient) pickConn() *grpc.ClientConn {
	c.locker.RLock()
	defer c.locker.RUnlock()

	countConns := len(c.conns)
	if countConns == 0 {
		return nil
	}
	if countConns == 1 {
		return c.conns[0]
	}

	for _, state := range []connectivity.State{
		connectivity.Ready,
		connectivity.Idle,
		connectivity.Connecting,
		connectivity.TransientFailure,
	} {
		available := []*grpc.ClientConn{}
		for _, conn := range c.conns {
			if conn.GetState() == state {
				available = append(available, conn)
			}
		}
		if len(available) > 0 {
			return c.randConn(available)
		}
	}

	return c.randConn(c.conns)
}

func (c *RPCClient) randConn(conns []*grpc.ClientConn) *grpc.ClientConn {
	l := len(conns)
	if l == 0 {
		return nil
	}
	if l == 1 {
		return conns[0]
	}
	return conns[rands.Int(0, l-1)]
}

func (c *RPCClient) Invoke(ctx context.Context, method string, args interface{}, reply interface{}, opts ...grpc.CallOption) error {
	conn := c.pickConn()
	if conn == nil {
		return errors.New("can not get available grpc connection")
	}

	atomic.AddInt64(&c.totalRequests, 1)
	start := time.Now()
	err := conn.Invoke(ctx, method, args, reply, opts...)
	costMs := time.Since(start).Milliseconds()
	atomic.AddInt64(&c.totalCostMs, costMs)

	if err != nil {
		atomic.AddInt64(&c.failedRequests, 1)
	}
	return err
}

func (c *RPCClient) GetAndResetMetrics() (total int64, failed int64, avgCostSeconds float64) {
	total = atomic.SwapInt64(&c.totalRequests, 0)
	failed = atomic.SwapInt64(&c.failedRequests, 0)
	costMs := atomic.SwapInt64(&c.totalCostMs, 0)

	if total > 0 {
		avgCostSeconds = float64(costMs) / float64(total) / 1000.0
	}
	return
}

func (c *RPCClient) NewStream(ctx context.Context, desc *grpc.StreamDesc, method string, opts ...grpc.CallOption) (grpc.ClientStream, error) {
	conn := c.pickConn()
	if conn == nil {
		return nil, errors.New("can not get available grpc connection")
	}
	return conn.NewStream(ctx, desc, method, opts...)
}