using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Xml.Serialization;

namespace D2Multi
{
    [XmlRoot("Accounts")]
    public class D2AccountsRoot
    {
        [XmlElement("Account")]
        public List<D2AccountPersisted> AccountList { get; set; } = new List<D2AccountPersisted>();
    }

    static class D2AccountsXmlStore
    {
        public static string DefaultPath =>
            Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "accounts.xml");

        public static List<D2Account> Load(string path)
        {
            if (!File.Exists(path))
                return new List<D2Account>();

            using (var stream = File.OpenRead(path))
            {
                var ser = new XmlSerializer(typeof(D2AccountsRoot));
                var root = (D2AccountsRoot)ser.Deserialize(stream);
                if (root?.AccountList == null)
                    return new List<D2Account>();

                var result = new List<D2Account>(root.AccountList.Count);
                foreach (var p in root.AccountList)
                {
                    var cipher = p?.EncryptedPassword ?? string.Empty;
                    result.Add(new D2Account
                    {
                        Name = p?.Name,
                        Email = p?.Email,
                        EncryptedPassword = cipher,
                        Password = D2AccountCrypto.Unprotect(cipher),
                        Characters = MapCharactersFromPersisted(p?.Characters),
                    });
                }
                return result;
            }
        }

        /// <summary>Builds XML from accounts; encrypts only here from <see cref="D2Account.Password"/> when non-empty.</summary>
        public static void Save(string path, IEnumerable<D2Account> accounts)
        {
            var dir = Path.GetDirectoryName(path);
            if (!string.IsNullOrEmpty(dir))
                Directory.CreateDirectory(dir);

            var persisted = (accounts ?? Enumerable.Empty<D2Account>())
                .Select(ToPersistedForXml)
                .ToList();

            var root = new D2AccountsRoot { AccountList = persisted };
            using (var stream = File.Create(path))
            {
                var ser = new XmlSerializer(typeof(D2AccountsRoot));
                ser.Serialize(stream, root);
            }
        }

        static D2AccountPersisted ToPersistedForXml(D2Account a)
        {
            string encrypted;
            if (!string.IsNullOrEmpty(a?.Password))
                encrypted = D2AccountCrypto.Protect(a.Password);
            else
                encrypted = a?.EncryptedPassword ?? string.Empty;

            return new D2AccountPersisted
            {
                Name = a?.Name,
                Email = a?.Email,
                EncryptedPassword = encrypted,
                Characters = MapCharactersToPersisted(a?.Characters),
            };
        }

        static List<D2Character> MapCharactersFromPersisted(List<D2CharacterPersisted> list)
        {
            if (list == null || list.Count == 0)
                return new List<D2Character>();
            var result = new List<D2Character>(list.Count);
            foreach (var cp in list)
            {
                if (cp == null)
                    continue;
                var missions = new List<D2Mission>();
                if (cp.Missions != null)
                {
                    foreach (var mp in cp.Missions)
                    {
                        if (mp == null)
                            continue;
                        missions.Add(new D2Mission
                        {
                            Level = mp.Level,
                            A1_Enpowered = mp.A1_Enpowered,
                            A5_Socket = mp.A5_Socket,
                        });
                    }
                }
                result.Add(new D2Character { Name = cp.Name, Class = cp.Class, Missions = missions });
            }
            return result;
        }

        static List<D2CharacterPersisted> MapCharactersToPersisted(List<D2Character> list)
        {
            if (list == null || list.Count == 0)
                return null;
            var result = new List<D2CharacterPersisted>(list.Count);
            foreach (var c in list)
            {
                if (c == null)
                    continue;
                var mpList = new List<D2MissionPersisted>();
                if (c.Missions != null)
                {
                    foreach (var m in c.Missions)
                    {
                        if (m == null)
                            continue;
                        mpList.Add(new D2MissionPersisted
                        {
                            Level = m.Level,
                            A1_Enpowered = m.A1_Enpowered,
                            A5_Socket = m.A5_Socket,
                        });
                    }
                }
                result.Add(new D2CharacterPersisted { Name = c.Name, Class = c.Class, Missions = mpList });
            }
            return result.Count == 0 ? null : result;
        }
    }
}