using System;
using System.Collections.Generic;
using System.Linq;

namespace SharpChat {
    public class UsersContext {
        [Flags]
        public enum NameTarget {
            None = 0,
            UserName = 1,
            NickName = 2,
            UserAndNickName = UserName | NickName,
        }

        private readonly List<UserInfo> Users = new();

        public int TotalCount { get; private set; }

        public UserInfo[] All => Users.ToArray();

        public UserInfo? Get(
            long? userId = null,
            string? name = null,
            NameTarget nameTarget = NameTarget.UserName
        ) {
            foreach(UserInfo info in Users) {
                if(userId != null && info.UserId != userId)
                    continue;
                if(name != null) {
                    // this could probably all fit in a single if condition, but it'd be massive and disgusting
                    // and require more thinking power than my goldfish brain can muster
                    bool match = false;
                    if(nameTarget.HasFlag(NameTarget.UserName) && info.UserName.Equals(name, StringComparison.InvariantCultureIgnoreCase))
                        match = true;
                    else if(nameTarget.HasFlag(NameTarget.NickName) && info.NickName.Equals(name, StringComparison.InvariantCultureIgnoreCase))
                        match = true;
                    if(!match)
                        continue;
                }

                return info;
            }

            return null;
        }

        public UserInfo[] GetMany(
            long[]? userIds = null,
            string[]? names = null,
            NameTarget namesTarget = NameTarget.UserName,
            int? minRank = null
        ) {
            List<UserInfo> users = new();

            foreach(UserInfo info in Users) {
                if(minRank != null && info.Rank < minRank)
                    continue;

                if(userIds != null && !userIds.Contains(info.UserId))
                    continue;

                if(names?.Length > 0) {
                    bool match = false;
                    foreach(string name in names) {
                        if(namesTarget.HasFlag(NameTarget.UserName) && info.UserName.Equals(name, StringComparison.InvariantCultureIgnoreCase))
                            match = true;
                        else if(namesTarget.HasFlag(NameTarget.NickName) && info.NickName.Equals(name, StringComparison.InvariantCultureIgnoreCase))
                            match = true;
                    }

                    if(!match)
                        continue;
                }

                users.Add(info);
            }

            return users.ToArray();
        }

        public void Add(UserInfo info) {
            if(Get(info.UserId, info.UserName) != null)
                throw new ArgumentException("A user with that id and/or name has already been registred.", nameof(info));

            Users.Add(info);
            ++TotalCount;
        }

        public void Remove(UserInfo info) {
            if(!Users.Contains(info)) {
                Remove(info.UserId);
                return;
            }

            Users.Remove(info);
            --TotalCount;
        }

        public void Remove(
            long? userId = null,
            string? name = null,
            NameTarget nameTarget = NameTarget.UserName
        ) {
            UserInfo? info = Get(userId, name, nameTarget);
            if(info == null)
                return;

            Users.Remove(info);
            --TotalCount;
        }
    }
}