using BirthdayBot.Data;
using Discord;
using Discord.WebSocket;
using System.Collections.Generic;
using System.Text;
using System.Threading.Tasks;

namespace BirthdayBot.UserInterface
{
    internal class HelpInfoCommands : CommandsCommon
    {
        private readonly Embed _helpEmbed;
        private readonly Embed _helpConfigEmbed;

        public HelpInfoCommands(Configuration cfg) : base(cfg)
        {
            var embeds = BuildHelpEmbeds();
            _helpEmbed = embeds.Item1;
            _helpConfigEmbed = embeds.Item2;
        }

        public override IEnumerable<(string, CommandHandler)> Commands =>
            new List<(string, CommandHandler)>() {
                ("help", CmdHelp),
                ("help-config", CmdHelpConfig),
                ("helpconfig", CmdHelpConfig),
                ("help-tzdata", CmdHelpTzdata),
                ("helptzdata", CmdHelpTzdata),
                ("help-message", CmdHelpMessage),
                ("helpmessage", CmdHelpMessage),
                ("info", CmdInfo),
                ("about", CmdInfo),
                ("invite", CmdInfo)
            };

        private static (Embed, Embed) BuildHelpEmbeds()
        {
            var cpfx = $"●`{CommandPrefix}";

            // Normal section
            var cmdField = new EmbedFieldBuilder()
            {
                Name = "Commands",
                Value = $"{cpfx}help`, `{CommandPrefix}info`, `{CommandPrefix}help-tzdata`\n"
                    + $" » Help and informational messages.\n"
                    + ListingCommands.DocUpcoming.Export() + "\n"
                    + UserCommands.DocSet.Export() + "\n"
                    + UserCommands.DocZone.Export() + "\n"
                    + UserCommands.DocRemove.Export() + "\n"
                    + ListingCommands.DocWhen.Export()
            };
            var cmdModField = new EmbedFieldBuilder()
            {
                Name = "Moderator actions",
                Value = $"{cpfx}config`\n"
                    + $" » Edit bot configuration. See `{CommandPrefix}help-config`.\n"
                    + ListingCommands.DocList.Export() + "\n"
                    + ManagerCommands.DocOverride.Export()
            };
            var helpRegular = new EmbedBuilder().AddField(cmdField).AddField(cmdModField);

            // Manager section
            var mpfx = cpfx + "config ";
            var configField1 = new EmbedFieldBuilder()
            {
                Name = "Basic settings",
                Value = $"{mpfx}role (role name or ID)`\n"
                    + " » Sets the role to apply to users having birthdays.\n"
                    + $"{mpfx}channel (channel name or ID)`\n"
                    + " » Sets the announcement channel. Leave blank to disable.\n"
                    + $"{mpfx}message (message)`, `{CommandPrefix}config messagepl (message)`\n"
                    + $" » Sets a custom announcement message. See `{CommandPrefix}help-message`.\n"
                    + $"{mpfx}ping (off|on)`\n"
                    + $" » Sets whether to ping the respective users in the announcement message.\n"
                    + $"{mpfx}zone (time zone name)`\n"
                    + $" » Sets the default server time zone. See `{CommandPrefix}help-tzdata`."
            };
            var configField2 = new EmbedFieldBuilder()
            {
                Name = "Access management",
                Value = $"{mpfx}modrole (role name, role ping, or ID)`\n"
                    + " » Establishes a role for bot moderators. Grants access to `bb.config` and `bb.override`.\n"
                    + $"{mpfx}block/unblock (user ping or ID)`\n"
                    + " » Prevents or allows usage of bot commands to the given user.\n"
                    + $"{mpfx}moderated on/off`\n"
                    + " » Prevents or allows using commands for all members excluding moderators."
            };

            var helpConfig = new EmbedBuilder()
            {
                Author = new EmbedAuthorBuilder() { Name = $"{CommandPrefix} config subcommands" },
                Description = "All the following subcommands are only usable by moderators and server managers."
            }.AddField(configField1).AddField(configField2);

            return (helpRegular.Build(), helpConfig.Build());
        }

        private async Task CmdHelp(ShardInstance instance, GuildConfiguration gconf,
                                   string[] param, SocketTextChannel reqChannel, SocketGuildUser reqUser)
            => await reqChannel.SendMessageAsync(embed: _helpEmbed).ConfigureAwait(false);

        private async Task CmdHelpConfig(ShardInstance instance, GuildConfiguration gconf,
                                         string[] param, SocketTextChannel reqChannel, SocketGuildUser reqUser)
            => await reqChannel.SendMessageAsync(embed: _helpConfigEmbed).ConfigureAwait(false);

        private async Task CmdHelpTzdata(ShardInstance instance, GuildConfiguration gconf,
                                         string[] param, SocketTextChannel reqChannel, SocketGuildUser reqUser)
        {
            const string tzhelp = "You may specify a time zone in order to have your birthday recognized with respect to your local time. "
                + "This bot only accepts zone names from the IANA Time Zone Database (a.k.a. Olson Database).\n\n"
                + "To find your zone: https://xske.github.io/tz/" + "\n"
                + "Interactive map: https://kevinnovak.github.io/Time-Zone-Picker/" + "\n"
                + "Complete list: https://en.wikipedia.org/wiki/List_of_tz_database_time_zones";
            var embed = new EmbedBuilder();
            embed.AddField(new EmbedFieldBuilder()
            {
                Name = "Time Zone Support",
                Value = tzhelp
            });
            await reqChannel.SendMessageAsync(embed: embed.Build()).ConfigureAwait(false);
        }

        private async Task CmdHelpMessage(ShardInstance instance, GuildConfiguration gconf,
                                          string[] param, SocketTextChannel reqChannel, SocketGuildUser reqUser)
        {
            const string msghelp = "The `message` and `messagepl` subcommands allow for editing the message sent into the announcement "
                + "channel (defined with `{0}config channel`). This feature is separated across two commands:\n"
                + "●`{0}config message`\n"
                + "●`{0}config messagepl`\n"
                + "The first command sets the message to be displayed when *one* user is having a birthday. The second command sets the "
                + "message for when *two or more* users are having birthdays ('pl' means plural). If only one of the two custom messages "
                + "are defined, it will be used for both cases.\n\n"
                + "To further allow customization, you may place the token `%n` in your message to specify where the name(s) should appear.\n"
                + "Leave the parameter blank to clear or reset the message to its default value.";
            const string msghelp2 = "As examples, these are the default announcement messages used by this bot:\n"
                + "`message`: {0}\n" + "`messagepl`: {1}";
            var embed = new EmbedBuilder().AddField(new EmbedFieldBuilder()
            {
                Name = "Custom announcement message",
                Value = string.Format(msghelp, CommandPrefix)
            }).AddField(new EmbedFieldBuilder()
            {
                Name = "Examples",
                Value = string.Format(msghelp2,
                    BackgroundServices.BirthdayRoleUpdate.DefaultAnnounce, BackgroundServices.BirthdayRoleUpdate.DefaultAnnouncePl)
            });
            await reqChannel.SendMessageAsync(embed: embed.Build()).ConfigureAwait(false);
        }

        private async Task CmdInfo(ShardInstance instance, GuildConfiguration gconf,
                                   string[] param, SocketTextChannel reqChannel, SocketGuildUser reqUser)
        {
            var strStats = new StringBuilder();
            var asmnm = System.Reflection.Assembly.GetExecutingAssembly().GetName();
            strStats.AppendLine("BirthdayBot v" + asmnm.Version.ToString(3));
            //strStats.AppendLine("Server count: " + Discord.Guilds.Count.ToString());
            // TODO restore this statistic
            strStats.AppendLine("Shard #" + instance.ShardId.ToString("00"));
            strStats.AppendLine("Uptime: " + Common.BotUptime);

            // TODO fun stats
            // current birthdays, total names registered, unique time zones

            var embed = new EmbedBuilder()
            {
                Author = new EmbedAuthorBuilder()
                {
                    Name = "Thank you for using Birthday Bot!",
                    IconUrl = instance.DiscordClient.CurrentUser.GetAvatarUrl()
                },
                // TODO this message needs an overhaul
                Description = "For more information regarding support, data retention, privacy, and other details, please refer to: "
                    + "https://github.com/NoiTheCat/BirthdayBot/blob/master/Readme.md" + "\n\n"
                    + "This bot is provided for free, without any paywalled 'premium' features. "
                    + "If you've found this bot useful, please consider contributing via the "
                    + "bot author's page on Ko-fi: https://ko-fi.com/noithecat."
            }.AddField(new EmbedFieldBuilder()
            {
                Name = "Statistics",
                Value = strStats.ToString()
            });
            await reqChannel.SendMessageAsync(embed: embed.Build()).ConfigureAwait(false);
        }
    }
}