package scope

import (
	"errors"
	"fmt"
	"strconv"
	"strings"

	"source.toby3d.me/toby3d/auth/internal/common"
)

// Scope represent single token scope supported by IndieAuth.
//
// NOTE(toby3d): Encapsulate enums in structs for extra compile-time safety:
// https://threedots.tech/post/safer-enums-in-go/#struct-based-enums
type Scope struct {
	scope string
}

var ErrScopeUnknown error = errors.New("unknown scope")

//nolint:gochecknoglobals // structs cannot be constants
var (
	Und = Scope{} // "und"

	// https://indieweb.org/scope#Micropub_Scopes
	Create   = Scope{"create"}   // "create"
	Delete   = Scope{"delete"}   // "delete"
	Draft    = Scope{"draft"}    // "draft"
	Media    = Scope{"media"}    // "media"
	Undelete = Scope{"undelete"} // "undelete"
	Update   = Scope{"update"}   // "update"

	// https://indieweb.org/scope#Microsub_Scopes
	Block    = Scope{"block"}    // "block"
	Channels = Scope{"channels"} // "channels"
	Follow   = Scope{"follow"}   // "follow"
	Mute     = Scope{"mute"}     // "mute"
	Read     = Scope{"read"}     // "read"

	// This scope requests access to the user's default profile information
	// which include the following properties: name, photo, url.
	//
	// NOTE(toby3d): https://indieauth.net/source/#profile-information
	Profile = Scope{"profile"} // "profile"

	// This scope requests access to the user's email address in the
	// following property: email.
	//
	// Note that because the profile scope is required when requesting
	// profile information, the email scope cannot be requested on its own
	// and must be requested along with the profile scope if desired.
	//
	// NOTE(toby3d): https://indieauth.net/source/#profile-information
	Email = Scope{"email"} // "email"
)

//nolint:gochecknoglobals // maps cannot be constants
var uidsScopes = map[string]Scope{
	Block.scope:    Block,
	Channels.scope: Channels,
	Create.scope:   Create,
	Delete.scope:   Delete,
	Draft.scope:    Draft,
	Email.scope:    Email,
	Follow.scope:   Follow,
	Media.scope:    Media,
	Mute.scope:     Mute,
	Profile.scope:  Profile,
	Read.scope:     Read,
	Undelete.scope: Undelete,
	Update.scope:   Update,
}

// Parse parses scope slug into Scope domain.
func Parse(uid string) (Scope, error) {
	if scope, ok := uidsScopes[strings.ToLower(uid)]; ok {
		return scope, nil
	}

	return Und, fmt.Errorf("%w: %s", ErrScopeUnknown, uid)
}

func (s *Scope) UnmarshalJSON(v []byte) error {
	src, err := strconv.Unquote(string(v))
	if err != nil {
		return fmt.Errorf("Scope: UnmarshalJSON: cannot unquote string: %w", err)
	}

	out, err := Parse(src)
	if err != nil {
		return fmt.Errorf("Scope: UnmarshalJSON: cannot parse scope: %w", err)
	}

	*s = out

	return nil
}

func (s Scope) MarshalJSON() ([]byte, error) {
	return []byte(strconv.Quote(s.scope)), nil
}

// String returns string representation of scope.
func (s Scope) String() string {
	if s == Und {
		return common.Und
	}

	return s.scope
}

func (s Scope) GoString() string {
	return "scope.Scope(" + s.String() + ")"
}