package common

import (
	"fmt"
	"strings"
)

// gameIDPrefix is the mandatory opaque-identifier prefix for one Game Lobby
// game record.
const gameIDPrefix = "game-"

// applicationIDPrefix is the mandatory opaque-identifier prefix for one
// Game Lobby application record.
const applicationIDPrefix = "application-"

// inviteIDPrefix is the mandatory opaque-identifier prefix for one Game
// Lobby invite record.
const inviteIDPrefix = "invite-"

// membershipIDPrefix is the mandatory opaque-identifier prefix for one
// Game Lobby membership record.
const membershipIDPrefix = "membership-"

// GameID identifies one game record owned by Game Lobby Service. The value
// is opaque and stable; only its `game-*` prefix is observable to callers.
type GameID string

// String returns GameID as its stored identifier string.
func (id GameID) String() string {
	return string(id)
}

// IsZero reports whether GameID does not contain a usable value.
func (id GameID) IsZero() bool {
	return strings.TrimSpace(string(id)) == ""
}

// Validate reports whether GameID is non-empty, already trimmed, and carries
// the frozen `game-*` opaque prefix.
func (id GameID) Validate() error {
	return validatePrefixedID("game id", string(id), gameIDPrefix)
}

// ApplicationID identifies one application record owned by Game Lobby
// Service. The value is opaque and stable; only its `application-*` prefix
// is observable to callers.
type ApplicationID string

// String returns ApplicationID as its stored identifier string.
func (id ApplicationID) String() string {
	return string(id)
}

// IsZero reports whether ApplicationID does not contain a usable value.
func (id ApplicationID) IsZero() bool {
	return strings.TrimSpace(string(id)) == ""
}

// Validate reports whether ApplicationID is non-empty, already trimmed, and
// carries the frozen `application-*` opaque prefix.
func (id ApplicationID) Validate() error {
	return validatePrefixedID("application id", string(id), applicationIDPrefix)
}

// InviteID identifies one invite record owned by Game Lobby Service. The
// value is opaque and stable; only its `invite-*` prefix is observable to
// callers.
type InviteID string

// String returns InviteID as its stored identifier string.
func (id InviteID) String() string {
	return string(id)
}

// IsZero reports whether InviteID does not contain a usable value.
func (id InviteID) IsZero() bool {
	return strings.TrimSpace(string(id)) == ""
}

// Validate reports whether InviteID is non-empty, already trimmed, and
// carries the frozen `invite-*` opaque prefix.
func (id InviteID) Validate() error {
	return validatePrefixedID("invite id", string(id), inviteIDPrefix)
}

// MembershipID identifies one membership record owned by Game Lobby
// Service. The value is opaque and stable; only its `membership-*` prefix
// is observable to callers.
type MembershipID string

// String returns MembershipID as its stored identifier string.
func (id MembershipID) String() string {
	return string(id)
}

// IsZero reports whether MembershipID does not contain a usable value.
func (id MembershipID) IsZero() bool {
	return strings.TrimSpace(string(id)) == ""
}

// Validate reports whether MembershipID is non-empty, already trimmed, and
// carries the frozen `membership-*` opaque prefix.
func (id MembershipID) Validate() error {
	return validatePrefixedID("membership id", string(id), membershipIDPrefix)
}

// validatePrefixedID reports whether raw is a non-empty, trimmed identifier
// with the given opaque prefix and a non-empty suffix. The label is used to
// format error messages.
func validatePrefixedID(label, raw, prefix string) error {
	switch {
	case strings.TrimSpace(raw) == "":
		return fmt.Errorf("%s must not be empty", label)
	case strings.TrimSpace(raw) != raw:
		return fmt.Errorf("%s must not contain surrounding whitespace", label)
	case !strings.HasPrefix(raw, prefix):
		return fmt.Errorf("%s must start with %q", label, prefix)
	case len(raw) == len(prefix):
		return fmt.Errorf("%s must carry a non-empty suffix after %q", label, prefix)
	default:
		return nil
	}
}