using System.Collections.Generic;
using System.Linq;
using Discord;
using Discord.WebSocket;
using NadekoBot.Services.Database.Models;

namespace NadekoBot.Modules.Permissions.Common
{
    public static class PermissionExtensions
    {
        public static bool CheckPermissions(this IEnumerable<Permissionv2> permsEnumerable, IUserMessage message,
            string commandName, string moduleName, out int permIndex)
        {
            var perms = permsEnumerable as List<Permissionv2> ?? permsEnumerable.ToList();

            for (int i = perms.Count - 1; i >= 0; i--)
            {
                var perm = perms[i];

                var result = perm.CheckPermission(message, commandName, moduleName);

                if (result == null)
                {
                    continue;
                }
                permIndex = i;
                return result.Value;
            }
            permIndex = -1; //defaut behaviour
            return true;
        }

        //null = not applicable
        //true = applicable, allowed
        //false = applicable, not allowed
        public static bool? CheckPermission(this Permissionv2 perm, IUserMessage message, string commandName, string moduleName)
        {
            if (!((perm.SecondaryTarget == SecondaryPermissionType.Command &&
                    perm.SecondaryTargetName.ToLowerInvariant() == commandName.ToLowerInvariant()) ||
                (perm.SecondaryTarget == SecondaryPermissionType.Module &&
                    perm.SecondaryTargetName.ToLowerInvariant() == moduleName.ToLowerInvariant()) ||
                    perm.SecondaryTarget == SecondaryPermissionType.AllModules))
                return null;

            var guildUser = message.Author as IGuildUser;

            switch (perm.PrimaryTarget)
            {
                case PrimaryPermissionType.User:
                    if (perm.PrimaryTargetId == message.Author.Id)
                        return perm.State;
                    break;
                case PrimaryPermissionType.Channel:
                    if (perm.PrimaryTargetId == message.Channel.Id)
                        return perm.State;
                    break;
                case PrimaryPermissionType.Role:        
                    if (guildUser == null)
                        break;
                    if (guildUser.RoleIds.Contains(perm.PrimaryTargetId))
                        return perm.State;
                    break;
                case PrimaryPermissionType.Server:
                    if (guildUser == null)
                        break;
                    return perm.State;
            }
            return null;
        }

        public static string GetCommand(this Permissionv2 perm, string prefix, SocketGuild guild = null)
        {
            var com = "";
            switch (perm.PrimaryTarget)
            {
                case PrimaryPermissionType.User:
                    com += "u";
                    break;
                case PrimaryPermissionType.Channel:
                    com += "c";
                    break;
                case PrimaryPermissionType.Role:
                    com += "r";
                    break;
                case PrimaryPermissionType.Server:
                    com += "s";
                    break;
            }

            switch (perm.SecondaryTarget)
            {
                case SecondaryPermissionType.Module:
                    com += "m";
                    break;
                case SecondaryPermissionType.Command:
                    com += "c";
                    break;
                case SecondaryPermissionType.AllModules:
                    com = "a" + com + "m";
                    break;
            }

            var secName = perm.SecondaryTarget == SecondaryPermissionType.Command ?
                prefix + perm.SecondaryTargetName : perm.SecondaryTargetName;
            com += " " + (perm.SecondaryTargetName != "*" ? secName + " " : "") + (perm.State ? "enable" : "disable") + " ";

            switch (perm.PrimaryTarget)
            {
                case PrimaryPermissionType.User:
                    com += guild?.GetUser(perm.PrimaryTargetId)?.ToString() ?? $"<@{perm.PrimaryTargetId}>";
                    break;
                case PrimaryPermissionType.Channel:
                    com += $"<#{perm.PrimaryTargetId}>";
                    break;
                case PrimaryPermissionType.Role:
                    com += guild?.GetRole(perm.PrimaryTargetId)?.ToString() ?? $"<@&{perm.PrimaryTargetId}>";
                    break;
                case PrimaryPermissionType.Server:
                    break;
            }

            return prefix + com;
        }

        public static IEnumerable<Permission> AsEnumerable(this Permission perm)
        {
            do yield return perm;
            while ((perm = perm.Next) != null);
        }
    }
}