package requestid // import "go.unistack.org/micro-wrapper-requestid/v3"

import (
	"context"
	"net/textproto"

	"go.unistack.org/micro/v3/client"
	"go.unistack.org/micro/v3/metadata"
	"go.unistack.org/micro/v3/server"
	"go.unistack.org/micro/v3/util/id"
)

var XRequestIDKey struct{}

// DefaultMetadataKey contains metadata key
var DefaultMetadataKey = textproto.CanonicalMIMEHeaderKey("x-request-id")

// DefaultMetadataFunc wil be used if user not provide own func to fill metadata
var DefaultMetadataFunc = func(ctx context.Context) (context.Context, error) {
	imd, ok := metadata.FromIncomingContext(ctx)
	if !ok {
		imd = metadata.New(1)
	}
	omd, ok := metadata.FromOutgoingContext(ctx)
	if !ok {
		omd = metadata.New(1)
	}
	v, iok := imd.Get(DefaultMetadataKey)
	if iok {
		if _, ook := omd.Get(DefaultMetadataKey); ook {
			return ctx, nil
		}
	}
	if !iok {
		uid, err := id.New()
		if err != nil {
			return ctx, err
		}
		v = uid
	}
	imd.Set(DefaultMetadataKey, v)
	omd.Set(DefaultMetadataKey, v)
	ctx = context.WithValue(ctx, XRequestIDKey, v)
	ctx = metadata.NewIncomingContext(ctx, imd)
	ctx = metadata.NewOutgoingContext(ctx, omd)

	return ctx, nil
}

type wrapper struct {
	client.Client
}

func NewClientWrapper() client.Wrapper {
	return func(c client.Client) client.Client {
		handler := &wrapper{
			Client: c,
		}
		return handler
	}
}

func NewClientCallWrapper() client.CallWrapper {
	return func(fn client.CallFunc) client.CallFunc {
		return func(ctx context.Context, addr string, req client.Request, rsp interface{}, opts client.CallOptions) error {
			var err error
			if ctx, err = DefaultMetadataFunc(ctx); err != nil {
				return err
			}
			return fn(ctx, addr, req, rsp, opts)
		}
	}
}

func (w *wrapper) Call(ctx context.Context, req client.Request, rsp interface{}, opts ...client.CallOption) error {
	var err error
	if ctx, err = DefaultMetadataFunc(ctx); err != nil {
		return err
	}
	return w.Client.Call(ctx, req, rsp, opts...)
}

func (w *wrapper) Stream(ctx context.Context, req client.Request, opts ...client.CallOption) (client.Stream, error) {
	var err error
	if ctx, err = DefaultMetadataFunc(ctx); err != nil {
		return nil, err
	}
	return w.Client.Stream(ctx, req, opts...)
}

func (w *wrapper) Publish(ctx context.Context, msg client.Message, opts ...client.PublishOption) error {
	var err error
	if ctx, err = DefaultMetadataFunc(ctx); err != nil {
		return err
	}
	return w.Client.Publish(ctx, msg, opts...)
}

func NewServerHandlerWrapper() server.HandlerWrapper {
	return func(fn server.HandlerFunc) server.HandlerFunc {
		return func(ctx context.Context, req server.Request, rsp interface{}) error {
			var err error
			if ctx, err = DefaultMetadataFunc(ctx); err != nil {
				return err
			}
			return fn(ctx, req, rsp)
		}
	}
}

func NewServerSubscriberWrapper() server.SubscriberWrapper {
	return func(fn server.SubscriberFunc) server.SubscriberFunc {
		return func(ctx context.Context, msg server.Message) error {
			var err error
			imd, ok := metadata.FromIncomingContext(ctx)
			if !ok {
				imd = metadata.New(1)
			}
			omd, ok := metadata.FromOutgoingContext(ctx)
			if !ok {
				omd = metadata.New(1)
			}
			if id, ok := msg.Header()[DefaultMetadataKey]; ok {
				imd.Set(DefaultMetadataKey, id)
				omd.Set(DefaultMetadataKey, id)
				ctx = metadata.NewIncomingContext(ctx, imd)
				ctx = metadata.NewOutgoingContext(ctx, omd)
			} else if ctx, err = DefaultMetadataFunc(ctx); err != nil {
				return err
			}
			return fn(ctx, msg)
		}
	}
}