package client

import (
	"context"
	"fmt"
	"time"

	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials"
)

type TokenAuth struct {
	Token    string
	TokenKey string
}

// Return value is mapped to request headers.
func (t TokenAuth) GetRequestMetadata(ctx context.Context, in ...string) (map[string]string, error) {
	return map[string]string{
		t.TokenKey: t.Token,
	}, nil
}

func (TokenAuth) RequireTransportSecurity() bool {
	return true
}

// Connector with gRPC dial option
type Connector struct {
	Host       string
	Port       int
	SSLName    string
	SSLCrtFile string
	// Deadline in seconds
	Deadline int
	// Token string in headers
	Token string
	// TokenKey default = "authorization"
	TokenKey string
}

// Connect for gRPC client
// those dial option has include in connect
// - WithTransportCredentials if SSLName and SSLCrtFile is valid value
// - WithInsecure if SSLName and SSLCrtFile is empty value
// - WithPerRPCCredentials (Token and custom token key only)
func (c *Connector) Connect(opts ...grpc.DialOption) (*grpc.ClientConn, error) {
	// tls config
	crtFile := c.SSLCrtFile
	sslName := c.SSLName
	if crtFile != "" && sslName != "" {
		cred, err := credentials.NewClientTLSFromFile(crtFile, sslName)
		if err != nil {
			return nil, err
		}
		opts = append(opts, grpc.WithTransportCredentials(cred))
	} else {
		opts = append(opts, grpc.WithInsecure())
	}
	// token
	if c.Token != "" {
		if c.TokenKey == "" {
			c.TokenKey = "authorization"
		}
		opts = append(opts, grpc.WithPerRPCCredentials(TokenAuth{
			Token:    c.Token,
			TokenKey: c.TokenKey,
		}))
	}
	addr := fmt.Sprintf("%s:%d", c.Host, c.Port)
	return grpc.Dial(addr, opts...)
}

// ContextWithDeadline TL;DR
func (c *Connector) ContextWithDeadline() (context.Context, context.CancelFunc) {
	deadline := time.Now().Add(time.Duration(c.Deadline) * time.Second)
	return context.WithDeadline(context.Background(), deadline)
}