// Copyright (C) 2021-present sam (starshines.gay)
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

using System.ComponentModel;
using Catalogger.Backend.Cache;
using Catalogger.Backend.Cache.InMemoryCache;
using Catalogger.Backend.Database;
using Catalogger.Backend.Database.Queries;
using Catalogger.Backend.Extensions;
using Catalogger.Backend.Services;
using Remora.Commands.Attributes;
using Remora.Commands.Groups;
using Remora.Discord.API;
using Remora.Discord.API.Abstractions.Objects;
using Remora.Discord.Commands.Attributes;
using Remora.Discord.Commands.Feedback.Services;
using Remora.Discord.Commands.Services;
using Remora.Discord.Extensions.Embeds;
using Remora.Rest.Core;
using IResult = Remora.Results.IResult;

namespace Catalogger.Backend.Bot.Commands;

[Group("ignored-channels")]
[Description("Manage channels ignored for logging.")]
[DiscordDefaultMemberPermissions(DiscordPermission.ManageGuild)]
public class IgnoreChannelCommands(
    ILogger logger,
    DatabaseContext db,
    IMemberCache memberCache,
    GuildCache guildCache,
    ChannelCache channelCache,
    PermissionResolverService permissionResolver,
    ContextInjectionService contextInjection,
    FeedbackService feedbackService
) : CommandGroup
{
    private readonly ILogger _logger = logger.ForContext<IgnoreChannelCommands>();

    [Command("add")]
    [Description("Add a channel to the list of ignored channels.")]
    public async Task<IResult> AddIgnoredChannelAsync(
        [ChannelTypes(
            ChannelType.GuildCategory,
            ChannelType.GuildText,
            ChannelType.GuildAnnouncement,
            ChannelType.GuildForum,
            ChannelType.GuildMedia,
            ChannelType.GuildVoice,
            ChannelType.GuildStageVoice
        )]
        [Description("The channel to ignore")]
            IChannel channel
    )
    {
        var (_, guildId) = contextInjection.GetUserAndGuild();
        var guildConfig = await db.GetGuildAsync(guildId);

        if (guildConfig.Channels.IgnoredChannels.Contains(channel.ID.Value))
            return await feedbackService.ReplyAsync(
                "That channel is already being ignored.",
                isEphemeral: true
            );

        guildConfig.Channels.IgnoredChannels.Add(channel.ID.Value);
        db.Update(guildConfig);
        await db.SaveChangesAsync();

        return await feedbackService.ReplyAsync(
            $"Successfully added {(channel.Type == ChannelType.GuildCategory ? channel.Name : $"<#{channel.ID}>")} to the list of ignored channels."
        );
    }

    [Command("remove")]
    [Description("Remove a channel from the list of ignored channels.")]
    public async Task<IResult> RemoveIgnoredChannelAsync(
        [Description("The channel to stop ignoring")] IChannel channel
    )
    {
        var (_, guildId) = contextInjection.GetUserAndGuild();
        var guildConfig = await db.GetGuildAsync(guildId);

        if (!guildConfig.Channels.IgnoredChannels.Contains(channel.ID.Value))
            return await feedbackService.ReplyAsync(
                "That channel is already not ignored.",
                isEphemeral: true
            );

        guildConfig.Channels.IgnoredChannels.Remove(channel.ID.Value);
        db.Update(guildConfig);
        await db.SaveChangesAsync();

        return await feedbackService.ReplyAsync(
            $"Successfully removed {(channel.Type == ChannelType.GuildCategory ? channel.Name : $"<#{channel.ID}>")} from the list of ignored channels."
        );
    }

    [Command("list")]
    [Description("List channels ignored for logging.")]
    public async Task<IResult> ListIgnoredChannelsAsync()
    {
        var (userId, guildId) = contextInjection.GetUserAndGuild();
        if (!guildCache.TryGet(guildId, out var guild))
            throw new CataloggerError("Guild not in cache");

        var guildChannels = channelCache.GuildChannels(guildId).ToList();
        var guildConfig = await db.GetGuildAsync(guildId);

        var member = await memberCache.TryGetAsync(guildId, userId);
        if (member == null)
            throw new CataloggerError("Executing member not found");

        var ignoredChannels = guildConfig
            .Channels.IgnoredChannels.Select(id =>
            {
                var channel = guildChannels.FirstOrDefault(c => c.ID.Value == id);
                if (channel == null)
                    return new IgnoredChannel(IgnoredChannelType.Unknown, DiscordSnowflake.New(id));

                var type = channel.Type switch
                {
                    ChannelType.GuildCategory => IgnoredChannelType.Category,
                    _ => IgnoredChannelType.Base,
                };

                return new IgnoredChannel(
                    type,
                    channel.ID,
                    permissionResolver
                        .GetChannelPermissions(guildId, member, channel)
                        .HasPermission(DiscordPermission.ViewChannel)
                );
            })
            .ToList();

        foreach (var ch in ignoredChannels)
        {
            _logger.Debug("Channel: {ChannelId}, type: {Type}", ch.Id, ch.Type);
        }

        var embed = new EmbedBuilder()
            .WithTitle($"Ignored channels in {guild.Name}")
            .WithColour(DiscordUtils.Purple);

        var nonVisibleCategories = ignoredChannels.Count(c =>
            c is { Type: IgnoredChannelType.Category, CanSee: false }
        );
        var visibleCategories = ignoredChannels
            .Where(c => c is { Type: IgnoredChannelType.Category, CanSee: true })
            .ToList();

        if (nonVisibleCategories != 0 || visibleCategories.Count != 0)
        {
            var value = string.Join("\n", visibleCategories.Select(c => $"<#{c.Id}>"));
            if (nonVisibleCategories != 0)
                value +=
                    $"\n\n{nonVisibleCategories} channel(s) are not shown as you do not have access to them.";

            embed.AddField("Categories", value);
        }

        var nonVisibleBase = ignoredChannels.Count(c =>
            c is { Type: IgnoredChannelType.Base, CanSee: false }
        );
        var visibleBase = ignoredChannels
            .Where(c => c is { Type: IgnoredChannelType.Base, CanSee: true })
            .ToList();

        if (nonVisibleBase != 0 || visibleBase.Count != 0)
        {
            var value = string.Join("\n", visibleBase.Select(c => $"<#{c.Id}>"));
            if (nonVisibleBase != 0)
                value +=
                    $"\n\n{nonVisibleBase} channel(s) are not shown as you do not have access to them.";

            embed.AddField("Channels", value);
        }

        var unknownChannels = string.Join(
            "\n",
            ignoredChannels
                .Where(c => c.Type == IgnoredChannelType.Unknown)
                .Select(c => $"{c.Id} <#{c.Id}>")
        );
        if (!string.IsNullOrWhiteSpace(unknownChannels))
        {
            embed.AddField("Unknown", unknownChannels);
        }

        return await feedbackService.ReplyAsync(embeds: [embed.Build().GetOrThrow()]);
    }

    private record struct IgnoredChannel(IgnoredChannelType Type, Snowflake Id, bool CanSee = true);

    private enum IgnoredChannelType
    {
        Unknown,
        Base,
        Category,
    }
}