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

using Myriad.Builders;
using Myriad.Types;

using Newtonsoft.Json.Linq;

using PluralKit.Core;

namespace PluralKit.Bot;

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

    private readonly HttpClient _client;
    private readonly DispatchService _dispatch;
    private readonly EmbedService _embeds;

    public Groups(EmbedService embeds, HttpClient client,
                  DispatchService dispatch)
    {
        _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 ctx.Repository.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 ctx.Repository.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.");
        }

        // todo: this is supposed to be a transaction, but it's not used in any useful way
        // consider removing it?
        using var conn = await ctx.Database.Obtain();
        var newGroup = await ctx.Repository.CreateGroup(ctx.System.Id, groupName);

        var dispatchData = new JObject();
        dispatchData.Add("name", groupName);

        if (ctx.Config.GroupDefaultPrivate)
        {
            var patch = new GroupPatch().WithAllPrivacy(PrivacyLevel.Private);
            await ctx.Repository.UpdateGroup(newGroup.Id, patch, conn);
            dispatchData.Merge(patch.ToJson());
        }

        _ = _dispatch.Dispatch(newGroup.Id, new UpdateDispatchData
        {
            Event = DispatchEvent.CREATE_GROUP,
            EventData = dispatchData
        });

        var reference = newGroup.Reference(ctx);

        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 **{reference}**"))
            .Field(new Embed.Field("Add members to the group",
                $"> pk;group **{reference}** add **MemberName**\n> pk;group **{reference}** add **Member1** **Member2** **Member3** (and so on...)"))
            .Field(new Embed.Field("Set the description",
                $"> pk;group **{reference}** description **This is my new group, and here is the description!**"))
            .Field(new Embed.Field("Set the group icon",
                $"> pk;group **{reference}** icon\n*(with an image attached)*"));
        await ctx.Reply($"{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 ctx.Repository.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 ctx.Repository.UpdateGroup(target.Id, new GroupPatch { Name = newName });

        await ctx.Reply($"{Emojis.Success} Group name changed from **{target.Name}** to **{newName}** (using {newName.Length}/{Limits.MaxGroupNameLength} characters).");
    }

    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(ctx)} 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));

                var reference = target.Reference(ctx);

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

                eb.Footer(new Embed.EmbedFooter($"Using {target.DisplayName.Length}/{Limits.MaxGroupNameLength} characters."));

                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 ctx.Repository.UpdateGroup(target.Id, patch);

            await ctx.Reply($"{Emojis.Success} Group display name cleared.");
            if (target.NamePrivacy == PrivacyLevel.Private)
                await ctx.Reply($"{Emojis.Warn} Since this group no longer has a display name set, their name privacy **can no longer take effect**.");
        }
        else
        {
            var newDisplayName = ctx.RemainderOrNull(false).NormalizeLineEndSpacing();

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

            await ctx.Reply($"{Emojis.Success} Group display name changed (using {newDisplayName.Length}/{Limits.MaxGroupNameLength} characters).");
        }
    }

    public async Task GroupDescription(Context ctx, PKGroup target)
    {
        ctx.CheckSystemPrivacy(target.System, target.DescriptionPrivacy);

        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(ctx)} 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(ctx)} description -raw`."
                        + (ctx.System?.Id == target.System
                            ? $" To clear it, type `pk;group {target.Reference(ctx)} description -clear`."
                            : "")
                            + $" Using {target.Description.Length}/{Limits.MaxDescriptionLength} characters."))
                    .Build());
            return;
        }

        ctx.CheckOwnGroup(target);

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

            await ctx.Reply($"{Emojis.Success} Group description changed (using {description.Length}/{Limits.MaxDescriptionLength} characters).");
        }
    }

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

            await ctx.Repository.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 ctx.Repository.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()
        {
            ctx.CheckSystemPrivacy(target.System, target.IconPrivacy);

            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(ctx)} 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 ctx.Repository.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 ctx.Repository.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()
        {
            ctx.CheckSystemPrivacy(target.System, target.DescriptionPrivacy);

            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(ctx)} 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 isOwnSystem = ctx.System?.Id == target.System;
        var matchedRaw = ctx.MatchRaw();
        var matchedClear = await ctx.MatchClear();

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

        ctx.CheckSystem().CheckOwnGroup(target);

        if (matchedClear)
        {
            await ctx.Repository.UpdateGroup(target.Id, new() { Color = Partial<string>.Null() });

            await ctx.Reply($"{Emojis.Success} Group color cleared.");
        }
        else
        {
            var color = ctx.RemainderOrNull();

            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 ctx.Repository.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.Id, system.GroupListPrivacy);

        // explanation of privacy lookup here:
        // - ParseListOptions checks list access privacy and sets the privacy filter (which members show up in list)
        // - RenderGroupList checks the indivual privacy for each member (NameFor, etc)
        // the own system is always allowed to look up their list
        var opts = ctx.ParseListOptions(ctx.DirectLookupContextFor(system.Id));
        await ctx.RenderGroupList(
            ctx.LookupContextFor(system.Id),
            system.Id,
            GetEmbedTitle(system, opts),
            system.Color,
            opts
        );
    }

    private string GetEmbedTitle(PKSystem target, ListOptions opts)
    {
        var title = new StringBuilder("Groups of ");

        if (target.Name != null)
            title.Append($"{target.Name} (`{target.Hid}`)");
        else
            title.Append($"`{target.Hid}`");

        if (opts.Search != null)
            title.Append($" matching **{opts.Search}**");

        return title.ToString();
    }

    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("Name", target.NamePrivacy.Explanation()))
                .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("Metadata (creation date)", target.MetadataPrivacy.Explanation()))
                .Field(new Embed.Field("Visibility", target.Visibility.Explanation()))
                .Description(
                    $"To edit privacy settings, use the command:\n> pk;group **{target.Reference(ctx)}** privacy **<subject>** **<level>**\n\n- `subject` is one of `name`, `description`, `icon`, `members`, `metadata`, `visibility`, or `all`\n- `level` is either `public` or `private`.")
                .Build());
            return;
        }

        async Task SetAll(PrivacyLevel level)
        {
            await ctx.Repository.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 ctx.Repository.UpdateGroup(target.Id, new GroupPatch().WithPrivacy(subject, level));

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

            var explanation = (subject, level) switch
            {
                (GroupPrivacySubject.Name, PrivacyLevel.Private) =>
                    "This group's name is now hidden from other systems, and will be replaced by the group's display name.",
                (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.Metadata, PrivacyLevel.Private) =>
                    "This group's metadata (eg. creation date) is now hidden from other systems.",
                (GroupPrivacySubject.List, PrivacyLevel.Private) =>
                    "This group's member list is now hidden from other systems.",

                (GroupPrivacySubject.Name, PrivacyLevel.Public) =>
                    "This group's name is no longer 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.Metadata, PrivacyLevel.Public) =>
                    "This group's metadata (eg. creation date) is no longer hidden from other systems.",
                (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 (subject == GroupPrivacySubject.Name && level == PrivacyLevel.Private && target.DisplayName == null)
                await ctx.Reply(
                    $"{Emojis.Warn} This group does not have a display name set, and name privacy **will not take effect**.");
        }

        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 ctx.Repository.DeleteGroup(target.Id);

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

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