// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package command

import (
	"encoding/json"
	"fmt"
)

// MarshalArgs encodes the given arguments to json.RawMessages. This function
// is used to construct arguments to a protocol.Command.
//
// Example usage:
//
//   jsonArgs, err := EncodeArgs(1, "hello", true, StructuredArg{42, 12.6})
//
func MarshalArgs(args ...interface{}) ([]json.RawMessage, error) {
	var out []json.RawMessage
	for _, arg := range args {
		argJSON, err := json.Marshal(arg)
		if err != nil {
			return nil, err
		}
		out = append(out, argJSON)
	}
	return out, nil
}

// UnmarshalArgs decodes the given json.RawMessages to the variables provided
// by args. Each element of args should be a pointer.
//
// Example usage:
//
//   var (
//       num int
//       str string
//       bul bool
//       structured StructuredArg
//   )
//   err := UnmarshalArgs(args, &num, &str, &bul, &structured)
//
func UnmarshalArgs(jsonArgs []json.RawMessage, args ...interface{}) error {
	if len(args) != len(jsonArgs) {
		return fmt.Errorf("DecodeArgs: expected %d input arguments, got %d JSON arguments", len(args), len(jsonArgs))
	}
	for i, arg := range args {
		if err := json.Unmarshal(jsonArgs[i], arg); err != nil {
			return err
		}
	}
	return nil
}