using System.Text;
using System.Text.RegularExpressions;

using Humanizer;

using Myriad.Builders;
using Myriad.Types;

using Newtonsoft.Json.Linq;

using NodaTime;

using PluralKit.Core;

namespace PluralKit.Bot;

public class Groups
{
    public enum AddRemoveOperation
    {
        Add,
        Remove
    }

    private readonly HttpClient _client;
    private readonly IDatabase _db;
    private readonly DispatchService _dispatch;
    private readonly EmbedService _embeds;
    private readonly ModelRepository _repo;

    public Groups(IDatabase db, ModelRepository repo, EmbedService embeds, HttpClient client,
                  DispatchService dispatch)
    {
        _db = db;
        _repo = repo;
        _embeds = embeds;
        _client = client;
        _dispatch = dispatch;
    }

    public async Task CreateGroup(Context ctx)
    {
        ctx.CheckSystem();

        // Check group name length
        var groupName = ctx.RemainderOrNull() ?? throw new PKSyntaxError("You must pass a group name.");
        if (groupName.Length > Limits.MaxGroupNameLength)
            throw new PKError($"Group name too long ({groupName.Length}/{Limits.MaxGroupNameLength} characters).");

        // Check group cap
        var existingGroupCount = await _repo.GetSystemGroupCount(ctx.System.Id);
        var groupLimit = ctx.Config.GroupLimitOverride ?? Limits.MaxGroupCount;
        if (existingGroupCount >= groupLimit)
            throw new PKError(
                $"System has reached the maximum number of groups ({groupLimit}). Please delete unused groups first in order to create new ones.");

        // Warn if there's already a group by this name
        var existingGroup = await _repo.GetGroupByName(ctx.System.Id, groupName);
        if (existingGroup != null)
        {
            var msg =
                $"{Emojis.Warn} You already have a group in your system with the name \"{existingGroup.Name}\" (with ID `{existingGroup.Hid}`). Do you want to create another group with the same name?";
            if (!await ctx.PromptYesNo(msg, "Create"))
                throw new PKError("Group creation cancelled.");
        }

        var newGroup = await _repo.CreateGroup(ctx.System.Id, groupName);

        _ = _dispatch.Dispatch(newGroup.Id,
            new UpdateDispatchData
            {
                Event = DispatchEvent.CREATE_GROUP,
                EventData = JObject.FromObject(new { name = groupName })
            });

        var eb = new EmbedBuilder()
            .Description(
                $"Your new group, **{groupName}**, has been created, with the group ID **`{newGroup.Hid}`**.\nBelow are a couple of useful commands:")
            .Field(new Embed.Field("View the group card", $"> pk;group **{newGroup.Reference()}**"))
            .Field(new Embed.Field("Add members to the group",
                $"> pk;group **{newGroup.Reference()}** add **MemberName**\n> pk;group **{newGroup.Reference()}** add **Member1** **Member2** **Member3** (and so on...)"))
            .Field(new Embed.Field("Set the description",
                $"> pk;group **{newGroup.Reference()}** description **This is my new group, and here is the description!**"))
            .Field(new Embed.Field("Set the group icon",
                $"> pk;group **{newGroup.Reference()}** icon\n*(with an image attached)*"));
        await ctx.Reply($"{Emojis.Success} Group created!", eb.Build());

        if (existingGroupCount >= Limits.WarnThreshold(groupLimit))
            await ctx.Reply(
                $"{Emojis.Warn} You are approaching the per-system group limit ({existingGroupCount} / {groupLimit} groups). Please review your group list for unused or duplicate groups.");
    }

    public async Task RenameGroup(Context ctx, PKGroup target)
    {
        ctx.CheckOwnGroup(target);

        // Check group name length
        var newName = ctx.RemainderOrNull() ?? throw new PKSyntaxError("You must pass a new group name.");
        if (newName.Length > Limits.MaxGroupNameLength)
            throw new PKError(
                $"New group name too long ({newName.Length}/{Limits.MaxMemberNameLength} characters).");

        // Warn if there's already a group by this name
        var existingGroup = await _repo.GetGroupByName(ctx.System.Id, newName);
        if (existingGroup != null && existingGroup.Id != target.Id)
        {
            var msg =
                $"{Emojis.Warn} You already have a group in your system with the name \"{existingGroup.Name}\" (with ID `{existingGroup.Hid}`). Do you want to rename this group to that name too?";
            if (!await ctx.PromptYesNo(msg, "Rename"))
                throw new PKError("Group rename cancelled.");
        }

        await _repo.UpdateGroup(target.Id, new GroupPatch { Name = newName });

        await ctx.Reply($"{Emojis.Success} Group name changed from **{target.Name}** to **{newName}**.");
    }

    public async Task GroupDisplayName(Context ctx, PKGroup target)
    {
        var noDisplayNameSetMessage = "This group does not have a display name set.";
        if (ctx.System?.Id == target.System)
            noDisplayNameSetMessage +=
                $" To set one, type `pk;group {target.Reference()} displayname <display name>`.";

        // No perms check, display name isn't covered by member privacy

        if (ctx.MatchRaw())
        {
            if (target.DisplayName == null)
                await ctx.Reply(noDisplayNameSetMessage);
            else
                await ctx.Reply($"```\n{target.DisplayName}\n```");
            return;
        }

        if (!ctx.HasNext(false))
        {
            if (target.DisplayName == null)
            {
                await ctx.Reply(noDisplayNameSetMessage);
            }
            else
            {
                var eb = new EmbedBuilder()
                    .Field(new Embed.Field("Name", target.Name))
                    .Field(new Embed.Field("Display Name", target.DisplayName));

                if (ctx.System?.Id == target.System)
                    eb.Description(
                        $"To change display name, type `pk;group {target.Reference()} displayname <display name>`."
                        + $"To clear it, type `pk;group {target.Reference()} displayname -clear`."
                        + $"To print the raw display name, type `pk;group {target.Reference()} displayname -raw`.");

                await ctx.Reply(embed: eb.Build());
            }

            return;
        }

        ctx.CheckOwnGroup(target);

        if (await ctx.MatchClear("this group's display name"))
        {
            var patch = new GroupPatch { DisplayName = Partial<string>.Null() };
            await _repo.UpdateGroup(target.Id, patch);

            await ctx.Reply($"{Emojis.Success} Group display name cleared.");
        }
        else
        {
            var newDisplayName = ctx.RemainderOrNull(false).NormalizeLineEndSpacing();

            var patch = new GroupPatch { DisplayName = Partial<string>.Present(newDisplayName) };
            await _repo.UpdateGroup(target.Id, patch);

            await ctx.Reply($"{Emojis.Success} Group display name changed.");
        }
    }

    public async Task GroupDescription(Context ctx, PKGroup target)
    {
        if (!target.DescriptionPrivacy.CanAccess(ctx.LookupContextFor(target.System)))
            throw Errors.LookupNotAllowed;

        var noDescriptionSetMessage = "This group does not have a description set.";
        if (ctx.System?.Id == target.System)
            noDescriptionSetMessage +=
                $" To set one, type `pk;group {target.Reference()} description <description>`.";

        if (ctx.MatchRaw())
        {
            if (target.Description == null)
                await ctx.Reply(noDescriptionSetMessage);
            else
                await ctx.Reply($"```\n{target.Description}\n```");
            return;
        }

        if (!ctx.HasNext(false))
        {
            if (target.Description == null)
                await ctx.Reply(noDescriptionSetMessage);
            else
                await ctx.Reply(embed: new EmbedBuilder()
                    .Title("Group description")
                    .Description(target.Description)
                    .Field(new Embed.Field("\u200B",
                        $"To print the description with formatting, type `pk;group {target.Reference()} description -raw`."
                        + (ctx.System?.Id == target.System
                            ? $" To clear it, type `pk;group {target.Reference()} description -clear`."
                            : "")))
                    .Build());
            return;
        }

        ctx.CheckOwnGroup(target);

        if (await ctx.MatchClear("this group's description"))
        {
            var patch = new GroupPatch { Description = Partial<string>.Null() };
            await _repo.UpdateGroup(target.Id, patch);
            await ctx.Reply($"{Emojis.Success} Group description cleared.");
        }
        else
        {
            var description = ctx.RemainderOrNull(false).NormalizeLineEndSpacing();
            if (description.IsLongerThan(Limits.MaxDescriptionLength))
                throw Errors.StringTooLongError("Description", description.Length, Limits.MaxDescriptionLength);

            var patch = new GroupPatch { Description = Partial<string>.Present(description) };
            await _repo.UpdateGroup(target.Id, patch);

            await ctx.Reply($"{Emojis.Success} Group description changed.");
        }
    }

    public async Task GroupIcon(Context ctx, PKGroup target)
    {
        async Task ClearIcon()
        {
            ctx.CheckOwnGroup(target);

            await _repo.UpdateGroup(target.Id, new GroupPatch { Icon = null });
            await ctx.Reply($"{Emojis.Success} Group icon cleared.");
        }

        async Task SetIcon(ParsedImage img)
        {
            ctx.CheckOwnGroup(target);

            await AvatarUtils.VerifyAvatarOrThrow(_client, img.Url);

            await _repo.UpdateGroup(target.Id, new GroupPatch { Icon = img.Url });

            var msg = img.Source switch
            {
                AvatarSource.User =>
                    $"{Emojis.Success} Group icon changed to {img.SourceUser?.Username}'s avatar!\n{Emojis.Warn} If {img.SourceUser?.Username} changes their avatar, the group icon will need to be re-set.",
                AvatarSource.Url => $"{Emojis.Success} Group icon changed to the image at the given URL.",
                AvatarSource.Attachment =>
                    $"{Emojis.Success} Group icon changed to attached image.\n{Emojis.Warn} If you delete the message containing the attachment, the group icon will stop working.",
                _ => throw new ArgumentOutOfRangeException()
            };

            // The attachment's already right there, no need to preview it.
            var hasEmbed = img.Source != AvatarSource.Attachment;
            await (hasEmbed
                ? ctx.Reply(msg, new EmbedBuilder().Image(new Embed.EmbedImage(img.Url)).Build())
                : ctx.Reply(msg));
        }

        async Task ShowIcon()
        {
            if (!target.IconPrivacy.CanAccess(ctx.LookupContextFor(target.System)))
                throw Errors.LookupNotAllowed;
            if ((target.Icon?.Trim() ?? "").Length > 0)
            {
                var eb = new EmbedBuilder()
                    .Title("Group icon")
                    .Image(new Embed.EmbedImage(target.Icon.TryGetCleanCdnUrl()));

                if (target.System == ctx.System?.Id)
                    eb.Description($"To clear, use `pk;group {target.Reference()} icon -clear`.");

                await ctx.Reply(embed: eb.Build());
            }
            else
            {
                throw new PKSyntaxError(
                    "This group does not have an icon set. Set one by attaching an image to this command, or by passing an image URL or @mention.");
            }
        }

        if (await ctx.MatchClear("this group's icon"))
            await ClearIcon();
        else if (await ctx.MatchImage() is { } img)
            await SetIcon(img);
        else
            await ShowIcon();
    }

    public async Task GroupBannerImage(Context ctx, PKGroup target)
    {
        async Task ClearBannerImage()
        {
            ctx.CheckOwnGroup(target);

            await _repo.UpdateGroup(target.Id, new GroupPatch { BannerImage = null });
            await ctx.Reply($"{Emojis.Success} Group banner image cleared.");
        }

        async Task SetBannerImage(ParsedImage img)
        {
            ctx.CheckOwnGroup(target);

            await AvatarUtils.VerifyAvatarOrThrow(_client, img.Url, true);

            await _repo.UpdateGroup(target.Id, new GroupPatch { BannerImage = img.Url });

            var msg = img.Source switch
            {
                AvatarSource.Url => $"{Emojis.Success} Group banner image changed to the image at the given URL.",
                AvatarSource.Attachment =>
                    $"{Emojis.Success} Group banner image changed to attached image.\n{Emojis.Warn} If you delete the message containing the attachment, the banner image will stop working.",
                AvatarSource.User => throw new PKError("Cannot set a banner image to an user's avatar."),
                _ => throw new ArgumentOutOfRangeException()
            };

            // The attachment's already right there, no need to preview it.
            var hasEmbed = img.Source != AvatarSource.Attachment;
            await (hasEmbed
                ? ctx.Reply(msg, new EmbedBuilder().Image(new Embed.EmbedImage(img.Url)).Build())
                : ctx.Reply(msg));
        }

        async Task ShowBannerImage()
        {
            if (!target.DescriptionPrivacy.CanAccess(ctx.LookupContextFor(target.System)))
                throw Errors.LookupNotAllowed;
            if ((target.BannerImage?.Trim() ?? "").Length > 0)
            {
                var eb = new EmbedBuilder()
                    .Title("Group banner image")
                    .Image(new Embed.EmbedImage(target.BannerImage));

                if (target.System == ctx.System?.Id)
                    eb.Description($"To clear, use `pk;group {target.Reference()} banner clear`.");

                await ctx.Reply(embed: eb.Build());
            }
            else
            {
                throw new PKSyntaxError(
                    "This group does not have a banner image set. Set one by attaching an image to this command, or by passing an image URL or @mention.");
            }
        }

        if (await ctx.MatchClear("this group's banner image"))
            await ClearBannerImage();
        else if (await ctx.MatchImage() is { } img)
            await SetBannerImage(img);
        else
            await ShowBannerImage();
    }

    public async Task GroupColor(Context ctx, PKGroup target)
    {
        var color = ctx.RemainderOrNull();
        if (await ctx.MatchClear())
        {
            ctx.CheckOwnGroup(target);

            var patch = new GroupPatch { Color = Partial<string>.Null() };
            await _repo.UpdateGroup(target.Id, patch);

            await ctx.Reply($"{Emojis.Success} Group color cleared.");
        }
        else if (!ctx.HasNext())
        {
            if (target.Color == null)
                if (ctx.System?.Id == target.System)
                    await ctx.Reply(
                        $"This group does not have a color set. To set one, type `pk;group {target.Reference()} color <color>`.");
                else
                    await ctx.Reply("This group does not have a color set.");
            else
                await ctx.Reply(embed: new EmbedBuilder()
                    .Title("Group color")
                    .Color(target.Color.ToDiscordColor())
                    .Thumbnail(new Embed.EmbedThumbnail($"https://fakeimg.pl/256x256/{target.Color}/?text=%20"))
                    .Description($"This group's color is **#{target.Color}**."
                                 + (ctx.System?.Id == target.System
                                     ? $" To clear it, type `pk;group {target.Reference()} color -clear`."
                                     : ""))
                    .Build());
        }
        else
        {
            ctx.CheckOwnGroup(target);

            if (color.StartsWith("#")) color = color.Substring(1);
            if (!Regex.IsMatch(color, "^[0-9a-fA-F]{6}$")) throw Errors.InvalidColorError(color);

            var patch = new GroupPatch { Color = Partial<string>.Present(color.ToLowerInvariant()) };
            await _repo.UpdateGroup(target.Id, patch);

            await ctx.Reply(embed: new EmbedBuilder()
                .Title($"{Emojis.Success} Group color changed.")
                .Color(color.ToDiscordColor())
                .Thumbnail(new Embed.EmbedThumbnail($"https://fakeimg.pl/256x256/{color}/?text=%20"))
                .Build());
        }
    }

    public async Task ListSystemGroups(Context ctx, PKSystem system)
    {
        if (system == null)
        {
            ctx.CheckSystem();
            system = ctx.System;
        }

        ctx.CheckSystemPrivacy(system, system.GroupListPrivacy);

        // TODO: integrate with the normal "search" system

        var pctx = LookupContext.ByNonOwner;
        if (ctx.MatchFlag("a", "all"))
        {
            if (system.Id == ctx.System.Id)
                pctx = LookupContext.ByOwner;
            else
                throw new PKError("You do not have permission to access this information.");
        }

        var groups = (await _db.Execute(conn => conn.QueryGroupList(system.Id)))
            .Where(g => g.Visibility.CanAccess(pctx))
            .OrderBy(g => g.Name, StringComparer.InvariantCultureIgnoreCase)
            .ToList();

        if (groups.Count == 0)
        {
            if (system.Id == ctx.System?.Id)
                await ctx.Reply("This system has no groups. To create one, use the command `pk;group new <name>`.");
            else
                await ctx.Reply("This system has no groups.");

            return;
        }

        var title = system.Name != null ? $"Groups of {system.Name} (`{system.Hid}`)" : $"Groups of `{system.Hid}`";
        await ctx.Paginate(groups.ToAsyncEnumerable(), groups.Count, 25, title, ctx.System.Color, Renderer);

        Task Renderer(EmbedBuilder eb, IEnumerable<ListedGroup> page)
        {
            eb.WithSimpleLineContent(page.Select(g =>
            {
                if (g.DisplayName != null)
                    return
                        $"[`{g.Hid}`] **{g.Name.EscapeMarkdown()}** ({g.DisplayName.EscapeMarkdown()}) ({"member".ToQuantity(g.MemberCount)})";
                return $"[`{g.Hid}`] **{g.Name.EscapeMarkdown()}** ({"member".ToQuantity(g.MemberCount)})";
            }));
            eb.Footer(new Embed.EmbedFooter($"{groups.Count} total."));
            return Task.CompletedTask;
        }
    }

    public async Task ShowGroupCard(Context ctx, PKGroup target)
    {
        var system = await GetGroupSystem(ctx, target);
        await ctx.Reply(embed: await _embeds.CreateGroupEmbed(ctx, system, target));
    }

    public async Task GroupPrivacy(Context ctx, PKGroup target, PrivacyLevel? newValueFromCommand)
    {
        ctx.CheckSystem().CheckOwnGroup(target);
        // Display privacy settings
        if (!ctx.HasNext() && newValueFromCommand == null)
        {
            await ctx.Reply(embed: new EmbedBuilder()
                .Title($"Current privacy settings for {target.Name}")
                .Field(new Embed.Field("Description", target.DescriptionPrivacy.Explanation()))
                .Field(new Embed.Field("Icon", target.IconPrivacy.Explanation()))
                .Field(new Embed.Field("Member list", target.ListPrivacy.Explanation()))
                .Field(new Embed.Field("Visibility", target.Visibility.Explanation()))
                .Description(
                    $"To edit privacy settings, use the command:\n> pk;group **{target.Reference()}** privacy **<subject>** **<level>**\n\n- `subject` is one of `description`, `icon`, `members`, `visibility`, or `all`\n- `level` is either `public` or `private`.")
                .Build());
            return;
        }

        async Task SetAll(PrivacyLevel level)
        {
            await _repo.UpdateGroup(target.Id, new GroupPatch().WithAllPrivacy(level));

            if (level == PrivacyLevel.Private)
                await ctx.Reply(
                    $"{Emojis.Success} All {target.Name}'s privacy settings have been set to **{level.LevelName()}**. Other accounts will now see nothing on the group card.");
            else
                await ctx.Reply(
                    $"{Emojis.Success} All {target.Name}'s privacy settings have been set to **{level.LevelName()}**. Other accounts will now see everything on the group card.");
        }

        async Task SetLevel(GroupPrivacySubject subject, PrivacyLevel level)
        {
            await _repo.UpdateGroup(target.Id, new GroupPatch().WithPrivacy(subject, level));

            var subjectName = subject switch
            {
                GroupPrivacySubject.Description => "description privacy",
                GroupPrivacySubject.Icon => "icon privacy",
                GroupPrivacySubject.List => "member list",
                GroupPrivacySubject.Visibility => "visibility",
                _ => throw new ArgumentOutOfRangeException($"Unknown privacy subject {subject}")
            };

            var explanation = (subject, level) switch
            {
                (GroupPrivacySubject.Description, PrivacyLevel.Private) =>
                    "This group's description is now hidden from other systems.",
                (GroupPrivacySubject.Icon, PrivacyLevel.Private) =>
                    "This group's icon is now hidden from other systems.",
                (GroupPrivacySubject.Visibility, PrivacyLevel.Private) =>
                    "This group is now hidden from group lists and member cards.",
                (GroupPrivacySubject.List, PrivacyLevel.Private) =>
                    "This group's member list is now hidden from other systems.",

                (GroupPrivacySubject.Description, PrivacyLevel.Public) =>
                    "This group's description is no longer hidden from other systems.",
                (GroupPrivacySubject.Icon, PrivacyLevel.Public) =>
                    "This group's icon is no longer hidden from other systems.",
                (GroupPrivacySubject.Visibility, PrivacyLevel.Public) =>
                    "This group is no longer hidden from group lists and member cards.",
                (GroupPrivacySubject.List, PrivacyLevel.Public) =>
                    "This group's member list is no longer hidden from other systems.",

                _ => throw new InvalidOperationException($"Invalid subject/level tuple ({subject}, {level})")
            };

            await ctx.Reply(
                $"{Emojis.Success} {target.Name}'s **{subjectName}** has been set to **{level.LevelName()}**. {explanation}");
        }

        if (ctx.Match("all") || newValueFromCommand != null)
            await SetAll(newValueFromCommand ?? ctx.PopPrivacyLevel());
        else
            await SetLevel(ctx.PopGroupPrivacySubject(), ctx.PopPrivacyLevel());
    }

    public async Task DeleteGroup(Context ctx, PKGroup target)
    {
        ctx.CheckOwnGroup(target);

        await ctx.Reply(
            $"{Emojis.Warn} Are you sure you want to delete this group? If so, reply to this message with the group's ID (`{target.Hid}`).\n**Note: this action is permanent.**");
        if (!await ctx.ConfirmWithReply(target.Hid))
            throw new PKError(
                $"Group deletion cancelled. Note that you must reply with your group ID (`{target.Hid}`) *verbatim*.");

        await _repo.DeleteGroup(target.Id);

        await ctx.Reply($"{Emojis.Success} Group deleted.");
    }

    public async Task GroupFrontPercent(Context ctx, PKGroup target)
    {
        var targetSystem = await GetGroupSystem(ctx, target);
        ctx.CheckSystemPrivacy(targetSystem, targetSystem.FrontHistoryPrivacy);

        var totalSwitches = await _repo.GetSwitchCount(targetSystem.Id);
        if (totalSwitches == 0) throw Errors.NoRegisteredSwitches;

        var durationStr = ctx.RemainderOrNull() ?? "30d";

        var now = SystemClock.Instance.GetCurrentInstant();

        var rangeStart = DateUtils.ParseDateTime(durationStr, true, ctx.Zone);
        if (rangeStart == null) throw Errors.InvalidDateTime(durationStr);
        if (rangeStart.Value.ToInstant() > now) throw Errors.FrontPercentTimeInFuture;

        var title = new StringBuilder($"Frontpercent of {target.DisplayName ?? target.Name} (`{target.Hid}`) in ");
        if (targetSystem.Name != null)
            title.Append($"{targetSystem.Name} (`{targetSystem.Hid}`)");
        else
            title.Append($"`{targetSystem.Hid}`");

        var ignoreNoFronters = ctx.MatchFlag("fo", "fronters-only");
        var showFlat = ctx.MatchFlag("flat");
        var frontpercent = await _db.Execute(c =>
            _repo.GetFrontBreakdown(c, targetSystem.Id, target.Id, rangeStart.Value.ToInstant(), now));
        await ctx.Reply(embed: await _embeds.CreateFrontPercentEmbed(frontpercent, targetSystem, target,
            ctx.Zone, ctx.LookupContextFor(targetSystem), title.ToString(), ignoreNoFronters, showFlat));
    }

    private async Task<PKSystem> GetGroupSystem(Context ctx, PKGroup target)
    {
        var system = ctx.System;
        if (system?.Id == target.System)
            return system;
        return await _repo.GetSystem(target.System)!;
    }
}