// Package grpc provides a gRPC options
package grpc

import (
	"context"

	"go.unistack.org/micro/v3/client"
	"google.golang.org/grpc"
	"google.golang.org/grpc/encoding"
)

var (
	// DefaultPoolMaxStreams maximum streams on a connection
	// (20)
	DefaultPoolMaxStreams = 20

	// DefaultPoolMaxIdle maximum idle conns of a pool
	// (50)
	DefaultPoolMaxIdle = 50

	// DefaultMaxRecvMsgSize maximum message that client can receive
	// (4 MB).
	DefaultMaxRecvMsgSize = 1024 * 1024 * 4

	// DefaultMaxSendMsgSize maximum message that client can send
	// (4 MB).
	DefaultMaxSendMsgSize = 1024 * 1024 * 4

	// DefaultServiceConfig enable load balancing
	DefaultServiceConfig = `{"loadBalancingPolicy":"round_robin"}`
)

type poolMaxStreams struct{}

// maximum streams on a connectioin
func PoolMaxStreams(n int) client.Option {
	return func(o *client.Options) {
		if o.Context == nil {
			o.Context = context.Background()
		}
		o.Context = context.WithValue(o.Context, poolMaxStreams{}, n)
	}
}

type poolMaxIdle struct{}

// maximum idle conns of a pool
func PoolMaxIdle(d int) client.Option {
	return func(o *client.Options) {
		if o.Context == nil {
			o.Context = context.Background()
		}
		o.Context = context.WithValue(o.Context, poolMaxIdle{}, d)
	}
}

type codecsKey struct{}

// gRPC Codec to be used to encode/decode requests for a given content type
func Codec(contentType string, c encoding.Codec) client.Option {
	return func(o *client.Options) {
		codecs := make(map[string]encoding.Codec)
		if o.Context == nil {
			o.Context = context.Background()
		}
		if v := o.Context.Value(codecsKey{}); v != nil {
			codecs = v.(map[string]encoding.Codec)
		}
		codecs[contentType] = c
		o.Context = context.WithValue(o.Context, codecsKey{}, codecs)
	}
}

type maxRecvMsgSizeKey struct{}

// MaxRecvMsgSize set the maximum size of message that client can receive.
func MaxRecvMsgSize(s int) client.Option {
	return func(o *client.Options) {
		if o.Context == nil {
			o.Context = context.Background()
		}
		o.Context = context.WithValue(o.Context, maxRecvMsgSizeKey{}, s)
	}
}

type maxSendMsgSizeKey struct{}

// MaxSendMsgSize set the maximum size of message that client can send.
func MaxSendMsgSize(s int) client.Option {
	return func(o *client.Options) {
		if o.Context == nil {
			o.Context = context.Background()
		}
		o.Context = context.WithValue(o.Context, maxSendMsgSizeKey{}, s)
	}
}

type grpcDialOptions struct{}

// DialOptions to be used to configure gRPC dial options
func DialOptions(opts ...grpc.DialOption) client.Option {
	return func(o *client.Options) {
		if o.Context == nil {
			o.Context = context.Background()
		}
		o.Context = context.WithValue(o.Context, grpcDialOptions{}, opts)
	}
}

type grpcCallOptions struct{}

// CallOptions to be used to configure gRPC call options
func CallOptions(opts ...grpc.CallOption) client.CallOption {
	return func(o *client.CallOptions) {
		if o.Context == nil {
			o.Context = context.Background()
		}
		o.Context = context.WithValue(o.Context, grpcCallOptions{}, opts)
	}
}

type serviceConfigKey struct{}

func ServiceConfig(str string) client.CallOption {
	return func(options *client.CallOptions) {
		if options.Context == nil {
			options.Context = context.Background()
		}
		options.Context = context.WithValue(options.Context, serviceConfigKey{}, str)
	}
}