package identity

import (
	"encoding/json"
	"errors"
	"fmt"
	"strings"
)

var ErrIdentityNotExist = errors.New("identity doesn't exist")

type ErrMultipleMatch struct {
	Matching []string
}

func (e ErrMultipleMatch) Error() string {
	return fmt.Sprintf("Multiple matching identities found:\n%s", strings.Join(e.Matching, "\n"))
}

// Custom unmarshaling function to allow package user to delegate
// the decoding of an Identity and distinguish between an Identity
// and a Bare.
//
// If the given message has a "id" field, it's considered being a proper Identity.
func UnmarshalJSON(raw json.RawMessage) (Interface, error) {
	// First try to decode as a normal Identity
	var i Identity

	err := json.Unmarshal(raw, &i)
	if err == nil && i.id != "" {
		return &i, nil
	}

	// abort if we have an error other than the wrong type
	if _, ok := err.(*json.UnmarshalTypeError); err != nil && !ok {
		return nil, err
	}

	// Fallback on a legacy Bare identity
	var b Bare

	err = json.Unmarshal(raw, &b)
	if err == nil && (b.name != "" || b.login != "") {
		return &b, nil
	}

	// abort if we have an error other than the wrong type
	if _, ok := err.(*json.UnmarshalTypeError); err != nil && !ok {
		return nil, err
	}

	return nil, fmt.Errorf("unknown identity type")
}

type Resolver interface {
	ResolveIdentity(id string) (Interface, error)
}