// Package client is an interface for an RPC client
package client // import "go.unistack.org/micro/v3/client"

import (
	"context"
	"time"

	"go.unistack.org/micro/v3/codec"
	"go.unistack.org/micro/v3/metadata"
)

var (
	// DefaultClient is the global default client
	DefaultClient = NewClient()
	// DefaultContentType is the default content-type if not specified
	DefaultContentType = ""
	// DefaultBackoff is the default backoff function for retries (minimum 10 millisecond and maximum 5 second)
	DefaultBackoff = BackoffInterval(10*time.Millisecond, 5*time.Second)
	// DefaultRetry is the default check-for-retry function for retries
	DefaultRetry = RetryNever
	// DefaultRetries is the default number of times a request is tried
	DefaultRetries = 0
	// DefaultRequestTimeout is the default request timeout
	DefaultRequestTimeout = time.Second * 5
	// DefaultPoolSize sets the connection pool size
	DefaultPoolSize = 100
	// DefaultPoolTTL sets the connection pool ttl
	DefaultPoolTTL = time.Minute
)

// Client is the interface used to make requests to services.
// It supports Request/Response via Transport and Publishing via the Broker.
// It also supports bidirectional streaming of requests.
type Client interface {
	Name() string
	Init(opts ...Option) error
	Options() Options
	NewMessage(topic string, msg interface{}, opts ...MessageOption) Message
	NewRequest(service string, endpoint string, req interface{}, opts ...RequestOption) Request
	Call(ctx context.Context, req Request, rsp interface{}, opts ...CallOption) error
	Stream(ctx context.Context, req Request, opts ...CallOption) (Stream, error)
	Publish(ctx context.Context, msg Message, opts ...PublishOption) error
	BatchPublish(ctx context.Context, msg []Message, opts ...PublishOption) error
	String() string
}

type (
	FuncCall         func(ctx context.Context, req Request, rsp interface{}, opts ...CallOption) error
	HookCall         func(next FuncCall) FuncCall
	FuncStream       func(ctx context.Context, req Request, opts ...CallOption) (Stream, error)
	HookStream       func(next FuncStream) FuncStream
	FuncPublish      func(ctx context.Context, msg Message, opts ...PublishOption) error
	HookPublish      func(next FuncPublish) FuncPublish
	FuncBatchPublish func(ctx context.Context, msg []Message, opts ...PublishOption) error
	HookBatchPublish func(next FuncBatchPublish) FuncBatchPublish
)

// Message is the interface for publishing asynchronously
type Message interface {
	Topic() string
	Payload() interface{}
	ContentType() string
	Metadata() metadata.Metadata
}

// Request is the interface for a synchronous request used by Call or Stream
type Request interface {
	// The service to call
	Service() string
	// The action to take
	Method() string
	// The endpoint to invoke
	Endpoint() string
	// The content type
	ContentType() string
	// The unencoded request body
	Body() interface{}
	// Write to the encoded request writer. This is nil before a call is made
	Codec() codec.Codec
	// indicates whether the request will be a streaming one rather than unary
	Stream() bool
}

// Response is the response received from a service
type Response interface {
	// Read the response
	Codec() codec.Codec
	// Header data
	Header() metadata.Metadata
	// Read the undecoded response
	Read() ([]byte, error)
}

// Stream is the interface for a bidirectional synchronous stream
type Stream interface {
	// Context for the stream
	Context() context.Context
	// The request made
	Request() Request
	// The response read
	Response() Response
	// Send will encode and send a request
	Send(msg interface{}) error
	// Recv will decode and read a response
	Recv(msg interface{}) error
	// SendMsg will encode and send a request
	SendMsg(msg interface{}) error
	// RecvMsg will decode and read a response
	RecvMsg(msg interface{}) error
	// Error returns the stream error
	Error() error
	// Close closes the stream
	Close() error
	// CloseSend closes the send direction of the stream
	CloseSend() error
}

// Option used by the Client
type Option func(*Options)

// CallOption used by Call or Stream
type CallOption func(*CallOptions)

// PublishOption used by Publish
type PublishOption func(*PublishOptions)

// MessageOption used by NewMessage
type MessageOption func(*MessageOptions)

// RequestOption used by NewRequest
type RequestOption func(*RequestOptions)