// 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.Models;
using Catalogger.Backend.Database.Repositories;
using Catalogger.Backend.Extensions;
using Remora.Commands.Attributes;
using Remora.Commands.Groups;
using Remora.Discord.API;
using Remora.Discord.API.Abstractions.Objects;
using Remora.Discord.API.Objects;
using Remora.Discord.Commands.Attributes;
using Remora.Discord.Commands.Feedback.Services;
using Remora.Discord.Commands.Services;
using Remora.Discord.Pagination.Extensions;
using Remora.Rest.Core;
using IResult = Remora.Results.IResult;

namespace Catalogger.Backend.Bot.Commands;

[Group("watchlist")]
[Description("Commands for managing the server's watchlist.")]
[DiscordDefaultMemberPermissions(DiscordPermission.ManageGuild)]
public class WatchlistCommands(
    WatchlistRepository watchlistRepository,
    GuildCache guildCache,
    IMemberCache memberCache,
    UserCache userCache,
    ContextInjectionService contextInjectionService,
    FeedbackService feedbackService
) : CommandGroup
{
    [Command("add")]
    [Description("Add a user to the watchlist.")]
    public async Task<IResult> AddAsync(
        [Description("The user to add")] IUser user,
        [Description("The reason for adding this user to the watchlist")] string reason
    )
    {
        var (userId, guildId) = contextInjectionService.GetUserAndGuild();

        var entry = await watchlistRepository.CreateEntryAsync(guildId, user.ID, userId, reason);
        return await feedbackService.ReplyAsync(
            $"Added {user.PrettyFormat()} to this server's watchlist, with the following reason:\n>>> {entry.Reason}"
        );
    }

    [Command("remove")]
    [Description("Remove a user from the watchlist.")]
    public async Task<IResult> RemoveAsync([Description("The user to remove")] IUser user)
    {
        var (userId, guildId) = contextInjectionService.GetUserAndGuild();
        if (!await watchlistRepository.RemoveEntryAsync(guildId, user.ID))
        {
            return await feedbackService.ReplyAsync(
                $"{user.PrettyFormat()} is not on the watchlist, so you can't remove them from it."
            );
        }

        return await feedbackService.ReplyAsync(
            $"Removed {user.PrettyFormat()} from the watchlist!"
        );
    }

    [Command("show")]
    [Description("Show the current watchlist.")]
    public async Task<IResult> ShowAsync()
    {
        var (userId, guildId) = contextInjectionService.GetUserAndGuild();
        if (!guildCache.TryGet(guildId, out var guild))
            throw new CataloggerError("Guild was not cached");

        var watchlist = await watchlistRepository.GetGuildWatchlistAsync(guildId);
        if (watchlist.Count == 0)
            return await feedbackService.ReplyAsync(
                "There are no entries on the watchlist right now."
            );

        var fields = new List<IEmbedField>();
        foreach (var entry in watchlist)
            fields.Add(await GenerateWatchlistEntryFieldAsync(guildId, entry));

        return await feedbackService.SendContextualPaginatedMessageAsync(
            userId,
            DiscordUtils.PaginateFields(
                fields,
                title: $"Watchlist for {guild.Name} ({fields.Count})",
                fieldsPerPage: 5
            )
        );
    }

    private async Task<EmbedField> GenerateWatchlistEntryFieldAsync(
        Snowflake guildId,
        Watchlist entry
    )
    {
        var user = await TryGetUserAsync(guildId, DiscordSnowflake.New(entry.UserId));
        var fieldName = user != null ? user.Tag() : $"unknown user {entry.UserId}";

        var moderator = await TryGetUserAsync(guildId, DiscordSnowflake.New(entry.ModeratorId));
        var modName =
            moderator != null
                ? moderator.PrettyFormat()
                : $"*(unknown user {entry.ModeratorId})* <@{entry.ModeratorId}>";

        return new EmbedField(
            Name: fieldName,
            Value: $"""
            **Moderator:** {modName}
            **Added:** <t:{entry.AddedAt.ToUnixTimeSeconds()}>
            **Reason:**
            >>> {entry.Reason} 
            """
        );
    }

    private async Task<IUser?> TryGetUserAsync(Snowflake guildId, Snowflake userId) =>
        (await memberCache.TryGetAsync(guildId, userId))?.User.Value
        ?? await userCache.GetUserAsync(userId);
}