import {
    ActionRowBuilder,
    ButtonBuilder,
    ButtonStyle,
    ChannelType,
    Client,
    CommandInteraction,
    Events,
    GatewayIntentBits,
    PermissionFlagsBits,
    REST,
    Routes,
    SlashCommandBuilder,
    SlashCommandStringOption,
    type ButtonInteraction,
    type ChatInputCommandInteraction,
} from "discord.js";

function requireEnv(key: string): string {
    let value = process.env[key];
    if (!value) {
        throw new Error(`Missing ${key} environment variable.`);
    }
    return value;
}

let token = requireEnv("DISCORD_TOKEN");
let clientId = requireEnv("DISCORD_CLIENT_ID");
let guildId = requireEnv("DISCORD_GUILD_ID");

let client = new Client({ intents: [GatewayIntentBits.Guilds] });

let commands = [
    {
        slashCommand: new SlashCommandBuilder()
            .setName("new")
            .setDescription("Create a new CTF")
            .addStringOption(
                new SlashCommandStringOption()
                    .setName("name")
                    .setDescription("Name for the new CTF")
                    .setRequired(true)
            ),
        handler: newCtf,
    },
    {
        slashCommand: new SlashCommandBuilder()
            .setName("archive")
            .setDescription("Make this CTF category read-only for everyone"),
        handler: makeCtfCategoryReadonly,
    },
];

let CATEGORY_BUTTON_PREFIX = "ctf-category:";

async function newCtf(interaction: ChatInputCommandInteraction) {
    if (!interaction.guild) {
        await interaction.reply({
            content: "This command can only be used inside a server.",
            flags: "Ephemeral",
        });
        return;
    }

    let name = interaction.options.getString("name", true);
    await interaction.deferReply({ flags: "Ephemeral" });

    let category = await interaction.guild.channels.create({
        name,
        type: ChannelType.GuildCategory,
        permissionOverwrites: [
            {
                id: interaction.guild.roles.everyone,
                deny: [PermissionFlagsBits.ViewChannel],
            }
        ],
    });

    await Promise.all([
        await interaction.guild.channels.create({
            name: "info",
            type: ChannelType.GuildText,
            parent: category.id,
            position: 1,
        }),
        await interaction.guild.channels.create({
            name: "general",
            type: ChannelType.GuildText,
            parent: category.id,
            position: 2,
        }),
        await interaction.guild.channels.create({
            name: "challs",
            type: ChannelType.GuildForum,
            parent: category.id,
            position: 3,
        }),
    ]);

    let commandChannel = (interaction.channelId && await interaction.guild.channels.fetch(interaction.channelId));

    if (!commandChannel || !commandChannel.isTextBased())
        throw new Error("Wth is this channel?");

    await commandChannel.send({
        components: [
            new ActionRowBuilder<ButtonBuilder>().addComponents(
                new ButtonBuilder()
                    .setCustomId(`${CATEGORY_BUTTON_PREFIX}${category.id}`)
                    .setLabel(`Join ${name}`)
                    .setStyle(ButtonStyle.Primary),
            ),
        ],
    });

    await interaction.editReply(
        `Created ${category.name}.`,
    );
}

async function makeCtfCategoryReadonly(interaction: ChatInputCommandInteraction) {
    if (!interaction.guild) {
        await interaction.reply({
            content: "This command can only be used inside a server.",
            flags: "Ephemeral",
        });
        return;
    }

    if (!interaction.channel || interaction.channel.type !== ChannelType.GuildText
        || !["general", "info"].includes(interaction.channel.name)
        || !interaction.channel.parentId
    ) {
        await interaction.reply({
            content: "This command can only be used in the `general` or `info` channel of a CTF category.",
            flags: "Ephemeral",
        });
        return;
    }

    let category = interaction.channel.parentId && await interaction.guild.channels.fetch(interaction.channel.parentId);
    if (!category || category.type !== ChannelType.GuildCategory) {
        await interaction.reply({
            content: "This command can only be used in the `general` or `info` channel of a CTF category.",
            flags: "Ephemeral",
        });
        return;
    }

    await interaction.deferReply({ flags: "Ephemeral" });

    let allChannels = await interaction.guild.channels.fetch();
    let categoryChildren = [...allChannels.values()].filter((channel) => {
        return channel !== null && "parentId" in channel && channel.parentId === category.id;
    });

    let infoChannel = categoryChildren.find((channel) => channel?.name === "info");
    let generalChannel = categoryChildren.find((channel) => channel?.name === "general");
    let challsChannel = categoryChildren.find((channel) => channel?.name === "challs");

    if (
        !infoChannel ||
        !generalChannel ||
        !challsChannel ||
        infoChannel.type !== ChannelType.GuildText ||
        generalChannel.type !== ChannelType.GuildText ||
        challsChannel.type !== ChannelType.GuildForum
    ) {
        await interaction.editReply("This command can only be used in the `general` or `info` channel of a CTF category.");
        return;
    }

    let everyoneRoleId = interaction.guild.roles.everyone.id;

    await category.permissionOverwrites.edit(everyoneRoleId, {
        ViewChannel: true,
        ReadMessageHistory: true,
        SendMessages: false,
        SendMessagesInThreads: false,
        CreatePublicThreads: false,
        CreatePrivateThreads: false,
    });

    await Promise.all(
        category.permissionOverwrites.cache
            .filter(overwrite => overwrite.id !== everyoneRoleId)
            .map(overwrite => category.permissionOverwrites.delete(overwrite.id))
    );

    for (let channel of [infoChannel, generalChannel, challsChannel]) {
        if (channel && "lockPermissions" in channel && typeof channel.lockPermissions === "function") {
            await channel.lockPermissions();
        }
    }

    await interaction.editReply(
        `Updated ${category.name}: @everyone can read, (mostly) no-one can write.`,
    );
}

async function handleJoinCtfButton(interaction: ButtonInteraction) {
    if (!interaction.guild) {
        await interaction.reply({
            content: "This button only works inside a server.",
            flags: "Ephemeral",
        });
        return;
    }

    let categoryId = interaction.customId.slice(CATEGORY_BUTTON_PREFIX.length);

    let categoryChannel = await interaction.guild.channels.fetch(categoryId);

    if (!categoryChannel || categoryChannel.type !== ChannelType.GuildCategory) {
        await interaction.reply({
            content: "That category no longer exists.",
            flags: "Ephemeral",
        });
        return;
    }

    await categoryChannel.permissionOverwrites.edit(interaction.user.id, {
        ViewChannel: true,
        SendMessages: true,
    });

    await interaction.reply({
        content: `Granted you access to ${categoryChannel.name}.`,
        flags: "Ephemeral",
    });
}

let rest = new REST({ version: "10" }).setToken(token);

async function registerSlashCommands() {
    await rest.put(Routes.applicationGuildCommands(clientId, guildId), {
        body: commands.map(command => command.slashCommand.toJSON()),
    });
}

client.once(Events.ClientReady, (readyClient) => {
    console.log(`Logged in as ${readyClient.user.tag}`);
});

client.on(Events.InteractionCreate, async (interaction) => {
    try {
        if (interaction.isChatInputCommand()) {
            for (let command of commands) {
                if (interaction.commandName === command.slashCommand.name) {
                    await command.handler(interaction);
                    break;
                }
            }
        } else if (interaction.isButton() && interaction.customId.startsWith(CATEGORY_BUTTON_PREFIX)) {
            await handleJoinCtfButton(interaction);
        }
    } catch (error) {
        if (interaction instanceof CommandInteraction) {
            console.error("Error while handling interaction", error);
            if (interaction.deferred || interaction.replied) {
                await interaction.followUp({
                    content: "Something went wrong! :(",
                    flags: "Ephemeral",
                });
            } else {
                await interaction.reply({
                    content: "Something went wrong! :(",
                    flags: "Ephemeral",
                });
            }
        }
    }
});

try {
    await registerSlashCommands();
    await client.login(token);
} catch (error) {
    console.error("Discord bot failed to start", error);
    process.exit(1);
}