package grpcall

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"sort"
	"strings"
	"time"

	"github.com/golang/protobuf/jsonpb"
	"github.com/jhump/protoreflect/desc"
	"github.com/jhump/protoreflect/dynamic"
	"github.com/jhump/protoreflect/dynamic/grpcdynamic"
	"github.com/samber/lo"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/keepalive"
	"google.golang.org/grpc/metadata"
	"google.golang.org/grpc/status"
)

type Grpcall struct {
	conn        *grpc.ClientConn
	pDescriptor ProtoDescriptor
}

// 构建请求函数
func (this Grpcall) Invoke(service, method, data string, headers []string) (*Response, error) {
	// 获取 gRPC 服务方法描述信息
	mtd, err := this.GetServiceMethodDescriptor(service, method)
	if err != nil {
		return nil, err
	}

	md := this.MakeMetadata(headers)

	ctx := metadata.NewOutgoingContext(context.Background(), md)

	anyResolver, err := this.GetAnyResolver()

	if err != nil {
		return nil, err
	}

	// service.method message 构建器
	msgFactory, err := this.MakeServiceMethodMessageFactory(mtd)

	if err != nil {
		return nil, err
	}

	stub := grpcdynamic.NewStubWithMessageFactory(this.conn, msgFactory)

	if mtd.IsClientStreaming() && mtd.IsServerStreaming() {
		return this.invokeBidiStream(ctx, stub, mtd, msgFactory, anyResolver, data)
	}

	if mtd.IsServerStreaming() {
		return this.invokeServStream(ctx, stub, mtd, msgFactory, anyResolver, data)
	}

	return this.invokeUnary(ctx, stub, mtd, msgFactory, anyResolver, data)
}

func (this Grpcall) invokeUnary(ctx context.Context, stub grpcdynamic.Stub, method *desc.MethodDescriptor, msgFactory *dynamic.MessageFactory, anyResolver jsonpb.AnyResolver, data string) (*Response, error) {
	// 创建请求 message
	req := msgFactory.NewMessage(method.GetInputType())
	// 将数据格式化到 message
	if err := NewJsonRequestParser(anyResolver, strings.NewReader(data)).Next(req); err != nil {
		return nil, err
	}

	respHeaders := &metadata.MD{}

	respMsg, err := stub.InvokeRpc(ctx, method, req, grpc.Header(respHeaders))

	respStatus, ok := status.FromError(err)

	if !ok || respStatus.Code() != codes.OK {
		return nil, fmt.Errorf("grpc call %q failed, %s", method.GetFullyQualifiedName(), err)
	}

	marshaler := jsonpb.Marshaler{
		EmitDefaults: true,
		AnyResolver:  anyResolver,
	}

	pReader, pWriter := io.Pipe()

	resp := &Response{
		method: method,
		header: respHeaders,
		recv:   pReader,
	}

	go func() {
		defer pWriter.Close()
		if err = marshaler.Marshal(pWriter, respMsg); err != nil {
			pWriter.CloseWithError(err)
		}
	}()

	return resp, err
}

func (this Grpcall) invokeServStream(ctx context.Context, stub grpcdynamic.Stub, method *desc.MethodDescriptor, msgFactory *dynamic.MessageFactory, anyResolver jsonpb.AnyResolver, data string) (*Response, error) {
	// 创建请求 message
	req := msgFactory.NewMessage(method.GetInputType())
	// 将数据格式化到 message
	if err := NewJsonRequestParser(anyResolver, strings.NewReader(data)).Next(req); err != nil {
		return nil, err
	}

	cancel_ctx, cancel := context.WithCancel(ctx)

	stream, err := stub.InvokeRpcServerStream(cancel_ctx, method, req)

	if err != nil {
		cancel()
		return nil, err
	}

	pReader, pWriter := io.Pipe()

	resp := &Response{
		method: method,
		header: &metadata.MD{},
		recv:   pReader,
		cancel: cancel,
	}

	go func() {
		msgParser := jsonpb.Marshaler{
			EmitDefaults: true,
			AnyResolver:  anyResolver,
		}

		defer func() {
			cancel()
			pWriter.Close()
		}()

		for {
			// 从流中接收消息
			msg, err := stream.RecvMsg()

			if err == io.EOF {
				return
			}

			if err != nil {
				pWriter.CloseWithError(err)
				return
			}

			if *resp.header, err = stream.Header(); err != nil {
				pWriter.CloseWithError(err)
				return
			}

			if err = msgParser.Marshal(pWriter, msg); err != nil {
				pWriter.CloseWithError(err)
				return
			}

			msg.Reset()
		}
	}()

	return resp, nil
}

func (this Grpcall) invokeBidiStream(ctx context.Context, stub grpcdynamic.Stub, method *desc.MethodDescriptor, msgFactory *dynamic.MessageFactory, anyResolver jsonpb.AnyResolver, data string) (*Response, error) {
	// 创建请求 message
	req := msgFactory.NewMessage(method.GetInputType())
	// 将数据格式化到 message
	if err := NewJsonRequestParser(anyResolver, strings.NewReader(data)).Next(req); err != nil {
		return nil, err
	}

	cancel_ctx, cancel := context.WithCancel(ctx)

	stream, err := stub.InvokeRpcBidiStream(cancel_ctx, method)

	if err != nil {
		cancel()
		return nil, err
	}

	if err := stream.SendMsg(req); err != nil {
		cancel()
		return nil, err
	}

	pRecvReader, pRecvWriter := io.Pipe()

	resp := &Response{
		method:        method,
		header:        &metadata.MD{},
		recv:          pRecvReader,
		send:          make(chan []byte),
		sendCompleted: make(chan error),
		cancel:        cancel,
	}

	// send
	go func() {
		defer func() {
			stream.CloseSend()
			cancel()
			close(resp.sendCompleted)
			close(resp.send)
		}()

		reqParser := jsonpb.Unmarshaler{AnyResolver: anyResolver}

		for {
			select {
			case <-cancel_ctx.Done():
				resp.sendCompleted <- nil
				return
			case <-ctx.Done():
				resp.sendCompleted <- nil
				return
			case msg, ok := <-resp.send:
				if !ok {
					resp.sendCompleted <- fmt.Errorf("read send message error")
					return
				}

				if err := reqParser.UnmarshalNext(json.NewDecoder(bytes.NewReader(msg)), req); err != nil {
					resp.sendCompleted <- err
					return
				}

				if err := stream.SendMsg(req); err != nil {
					resp.sendCompleted <- err
					return
				}
			}

			resp.sendCompleted <- nil
		}
	}()

	// recv
	go func() {
		msgParser := jsonpb.Marshaler{
			EmitDefaults: true,
			AnyResolver:  anyResolver,
		}

		defer func() {
			cancel()
			pRecvWriter.Close()
		}()

		for {
			// 从流中接收消息
			msg, err := stream.RecvMsg()

			if err == io.EOF {
				return
			}

			if err != nil {
				pRecvWriter.CloseWithError(err)
				return
			}

			if *resp.header, err = stream.Header(); err != nil {
				pRecvWriter.CloseWithError(err)
				return
			}

			if err = msgParser.Marshal(pRecvWriter, msg); err != nil {
				pRecvWriter.CloseWithError(err)
				return
			}

			msg.Reset()
		}
	}()

	return resp, nil
}

func (this Grpcall) GetClientConn() *grpc.ClientConn {
	return this.conn
}

func (this Grpcall) GetAnyResolver() (jsonpb.AnyResolver, error) {
	files, err := this.GetAllFilesDescriptor()

	if err != nil {
		return nil, err
	}

	dExtension := dynamic.ExtensionRegistry{}

	for _, fd := range files {
		dExtension.AddExtensionsFromFile(fd)
	}

	mf := dynamic.NewMessageFactoryWithExtensionRegistry(&dExtension)

	return dynamic.AnyResolver(mf, files...), nil
}

func (this Grpcall) GetProtoDescriptor() ProtoDescriptor {
	return this.pDescriptor
}

func (this Grpcall) GetAllFilesDescriptor() ([]*desc.FileDescriptor, error) {
	return this.pDescriptor.GetAllFiles()
}

// 获取所有服务
func (this Grpcall) GetServices() ([]string, error) {
	return this.pDescriptor.ListServices()
}

// 获取服务下的所有方法
func (this Grpcall) GetServiceMethods(name string) ([]string, error) {
	if dsc, err := this.pDescriptor.FindSymbol(name); err != nil {
		return nil, err
	} else if sd, ok := dsc.(*desc.ServiceDescriptor); !ok {
		return nil, fmt.Errorf("%s, not found methods", name)
	} else {
		methods := make([]string, 0, len(sd.GetMethods()))

		for _, method := range sd.GetMethods() {
			methods = append(methods, method.GetFullyQualifiedName())
		}

		sort.Strings(methods)
		return methods, nil
	}
}

// 获取 gRPC 服务描述
func (this Grpcall) GetServiceDescriptor(service string) (*desc.ServiceDescriptor, error) {
	if service == "" {
		return nil, fmt.Errorf("service name is invalid")
	}

	dsc, err := this.pDescriptor.FindSymbol(service)

	if err != nil {
		return nil, err
	}

	sd, ok := dsc.(*desc.ServiceDescriptor)
	if !ok {
		return nil, fmt.Errorf("server not expose service, %q", service)
	}

	return sd, nil
}

// 获取 gRPC service.method 描述
func (this Grpcall) GetServiceMethodDescriptor(service, method string) (*desc.MethodDescriptor, error) {
	serv, err := this.GetServiceDescriptor(service)

	if err != nil {
		return nil, err
	}

	if mtd := serv.FindMethodByName(method); mtd != nil {
		return mtd, nil
	}

	return nil, fmt.Errorf("service %q does not include a method named %q", service, method)
}

// 生成 service.method message
func (this *Grpcall) MakeServiceMethodMessageFactory(method *desc.MethodDescriptor) (*dynamic.MessageFactory, error) {
	// 扩展字段的信息，包括扩展字段的名称、标识符、类型等。用于注册扩展、查找扩展、解析扩展以及处理扩展字段的值。
	var ext dynamic.ExtensionRegistry

	excluded := []string{}

	if err := this.RegServiceMethoddMessageExtensions(&ext, method.GetInputType(), excluded); err != nil {
		return nil, fmt.Errorf("register service.method extensions for message %s: %v", method.GetInputType().GetFullyQualifiedName(), err)
	}

	if err := this.RegServiceMethoddMessageExtensions(&ext, method.GetOutputType(), excluded); err != nil {
		return nil, fmt.Errorf("register service.method extensions for message %s: %v", method.GetOutputType().GetFullyQualifiedName(), err)
	}

	return dynamic.NewMessageFactoryWithExtensionRegistry(&ext), nil
}

// 注册 service.method message extensions
func (this Grpcall) RegServiceMethoddMessageExtensions(msgExt *dynamic.ExtensionRegistry, msg *desc.MessageDescriptor, excluded []string) error {
	msgTypeName := msg.GetFullyQualifiedName()

	// 避免重复注册
	if lo.Contains(excluded, msgTypeName) {
		return nil
	} else {
		excluded = append(excluded, msgTypeName)
	}

	// 注册 message extensions 信息
	if len(msg.GetExtensionRanges()) > 0 {
		fds, err := this.pDescriptor.AllExtensionsForType(msgTypeName)

		if err != nil {
			return fmt.Errorf("failed to query for extensions of type %s: %v", msgTypeName, err)
		}

		for i := 0; i < len(fds); i++ {
			if err := msgExt.AddExtension(fds[i]); err != nil {
				return fmt.Errorf("could not register extension %s of type %s: %v", fds[i].GetFullyQualifiedName(), msgTypeName, err)
			}
		}
	}

	// 递归注册 message 所有字段
	for _, msgField := range msg.GetFields() {
		if msgField.GetMessageType() == nil {
			continue
		}
		if err := this.RegServiceMethoddMessageExtensions(msgExt, msgField.GetMessageType(), excluded); err != nil {
			return err
		}
	}

	return nil
}

func (this Grpcall) MakeMetadata(headers []string) metadata.MD {
	md := make(metadata.MD)
	for _, part := range headers {
		if part != "" {
			pieces := strings.SplitN(part, ":", 2)
			if len(pieces) == 1 {
				pieces = append(pieces, "") // if no value was specified, just make it "" (maybe the header value doesn't matter)
			}
			headerName := strings.ToLower(strings.TrimSpace(pieces[0]))
			val := strings.TrimSpace(pieces[1])
			if strings.HasSuffix(headerName, "-bin") {
				if v, err := metadata_decode(val); err == nil {
					val = v
				}
			}
			md[headerName] = append(md[headerName], val)
		}
	}
	return md
}

func (this Grpcall) Close() error {
	return this.conn.Close()
}

func NewGrpcall(addr string, protosets []string, opts ...grpc.DialOption) (g *Grpcall, err error) {
	if addr == "" {
		return nil, fmt.Errorf("addr is invalid, %s", addr)
	}

	g = &Grpcall{}

	opts = append(opts,
		grpc.WithKeepaliveParams(keepalive.ClientParameters{
			Time:    64 * time.Second,
			Timeout: 64 * time.Second,
		}),
		grpc.WithBlock(),
		grpc.FailOnNonTempDialError(true),
	)

	if conn, err := grpc.Dial(addr, opts...); err != nil {
		return nil, err
	} else {
		g.conn = conn
	}

	if len(protosets) == 0 {
		g.pDescriptor, err = NewServProtoDescriptor(g.conn)
	} else {
		g.pDescriptor, err = NewFileProtoDescriptor(protosets)
	}

	return g, err
}