package room

import (
	"fmt"
	"sort"
	"strings"
)

type RoomPermission int

const (
	PermSendChat RoomPermission = iota
	PermViewChatHistory
	PermViewMembers
	PermSubscribe
	PermWatchRoom
	PermPublish
	PermStopStream
	PermBroadcast
	PermManageMembers
	PermAddMembers
	PermRemoveMembers
	PermManagePermissions
	PermManageRoom
	PermDeleteRoom
	PermDeleteChatMessages
	PermControlStream
	_permCount
)

func (p RoomPermission) Bit() uint64 { return 1 << uint(p) }
func (p RoomPermission) String() string {
	switch p {
	case PermSendChat:
		return "send_chat"
	case PermViewChatHistory:
		return "view_chat_history"
	case PermViewMembers:
		return "view_members"
	case PermSubscribe:
		return "subscribe"
	case PermWatchRoom:
		return "watch_room"
	case PermPublish:
		return "publish"
	case PermStopStream:
		return "stop_stream"
	case PermBroadcast:
		return "broadcast"
	case PermManageMembers:
		return "manage_members"
	case PermAddMembers:
		return "add_members"
	case PermRemoveMembers:
		return "remove_members"
	case PermManagePermissions:
		return "manage_permissions"
	case PermManageRoom:
		return "manage_room"
	case PermDeleteRoom:
		return "delete_room"
	case PermDeleteChatMessages:
		return "delete_chat_messages"
	case PermControlStream:
		return "control_stream"
	default:
		return fmt.Sprintf("perm_%d", int(p))
	}
}

func ParsePermission(s string) (RoomPermission, error) {
	switch strings.ToLower(strings.TrimSpace(s)) {
	case "send_chat", "sendchat", "chat", "room:chat":
		return PermSendChat, nil
	case "view_chat_history", "viewchathistory":
		return PermViewChatHistory, nil
	case "view_members", "viewmembers", "members:view":
		return PermViewMembers, nil
	case "subscribe", "room:subscribe":
		return PermSubscribe, nil
	case "watch", "watch_room", "room:watch":
		return PermWatchRoom, nil
	case "publish", "room:publish":
		return PermPublish, nil
	case "stop", "stop_stream", "room:stop":
		return PermStopStream, nil
	case "broadcast", "room:broadcast":
		return PermBroadcast, nil
	case "manage_members", "managemembers":
		return PermManageMembers, nil
	case "add_members", "addmembers":
		return PermAddMembers, nil
	case "remove_members", "removemembers", "kick":
		return PermRemoveMembers, nil
	case "manage_permissions", "managepermissions":
		return PermManagePermissions, nil
	case "manage_room", "manageroom", "room:manage":
		return PermManageRoom, nil
	case "delete_room", "deleteroom", "room:delete":
		return PermDeleteRoom, nil
	case "delete_chat_messages", "deletechat":
		return PermDeleteChatMessages, nil
	case "control_stream", "controlstream":
		return PermControlStream, nil
	default:
		return 0, fmt.Errorf("unknown permission %q", s)
	}
}

type PermissionSet uint64

func (s PermissionSet) Has(p RoomPermission) bool { return uint64(s)&p.Bit() != 0 }
func (s PermissionSet) HasAll(o PermissionSet) bool { return uint64(s)&uint64(o) == uint64(o) }
func (s PermissionSet) HasAny(o PermissionSet) bool { return uint64(s)&uint64(o) != 0 }
func (s *PermissionSet) Grant(p RoomPermission) { *s |= PermissionSet(p.Bit()) }
func (s *PermissionSet) Revoke(p RoomPermission) { *s &^= PermissionSet(p.Bit()) }
func (s PermissionSet) Bits() uint64 { return uint64(s) }
func (s PermissionSet) List() []RoomPermission {
	var out []RoomPermission
	for i := 0; i < int(_permCount); i++ {
		p := RoomPermission(i)
		if s.Has(p) {
			out = append(out, p)
		}
	}
	return out
}
func (s PermissionSet) Names() []string {
	list := s.List()
	names := make([]string, len(list))
	for i, p := range list {
		names[i] = p.String()
	}
	sort.Strings(names)
	return names
}

func (s PermissionSet) String() string { return strings.Join(s.Names(), ",") }

func AllPermissions() PermissionSet {
	var all PermissionSet
	for i := 0; i < int(_permCount); i++ {
		all.Grant(RoomPermission(i))
	}
	return all
}

var (
	PermAll   = AllPermissions()
	PermNone  = PermissionSet(0)

	PermDefaultCreator = PermAll
	PermDefaultAdmin = func() PermissionSet {
		var s PermissionSet
		s.Grant(PermSendChat)
		s.Grant(PermViewChatHistory)
		s.Grant(PermViewMembers)
		s.Grant(PermSubscribe)
		s.Grant(PermWatchRoom)
		s.Grant(PermPublish)
		s.Grant(PermStopStream)
		s.Grant(PermBroadcast)
		s.Grant(PermManageMembers)
		s.Grant(PermAddMembers)
		s.Grant(PermRemoveMembers)
		s.Grant(PermManagePermissions)
		s.Grant(PermManageRoom)
		s.Grant(PermDeleteChatMessages)
		s.Grant(PermControlStream)
		return s
	}()
	PermDefaultMember = func() PermissionSet {
		var s PermissionSet
		s.Grant(PermSendChat)
		s.Grant(PermViewChatHistory)
		s.Grant(PermViewMembers)
		s.Grant(PermSubscribe)
		s.Grant(PermWatchRoom)
		s.Grant(PermPublish)
		s.Grant(PermStopStream)
		return s
	}()
	PermDefaultGuest = func() PermissionSet {
		var s PermissionSet
		s.Grant(PermViewChatHistory)
		s.Grant(PermViewMembers)
		s.Grant(PermSubscribe)
		s.Grant(PermWatchRoom)
		return s
	}()
	PermGuestAssignable = PermDefaultGuest | func() PermissionSet {
		var s PermissionSet
		s.Grant(PermSendChat)
		return s
	}()
)

func DefaultForRole(r RoomRole) PermissionSet {
	switch r {
	case RoleCreator:
		return PermDefaultCreator
	case RoleAdmin:
		return PermDefaultAdmin
	case RoleMember:
		return PermDefaultMember
	case RoleGuest:
		return PermDefaultGuest
	default:
		return PermDefaultGuest
	}
}