use crate::VCs;
use crate::command::State;
use snafu::{OptionExt, Snafu};
use std::sync::LazyLock;
use twilight_model::channel::message::{Embed, MessageFlags};
use twilight_model::http::interaction::{InteractionResponse, InteractionResponseType};
use twilight_model::id::marker::UserMarker;
use twilight_model::{
    application::{
        command::{Command, CommandType},
        interaction::Interaction,
    },
    id::{
        Id,
        marker::{ChannelMarker, GuildMarker},
    },
};
use twilight_util::builder::InteractionResponseDataBuilder;
use twilight_util::builder::command::CommandBuilder;
use twilight_util::builder::embed::EmbedBuilder;

const NAME: &str = "leave";
const DESCRIPTION: &str = "The bot will leave the VC it's in (so it won't record anyone anymore)";

pub static COMMAND: LazyLock<Command> = LazyLock::new(|| {
    CommandBuilder::new(NAME, DESCRIPTION, CommandType::ChatInput)
        .validate()
        .expect("command wasn't correct")
        .build()
});

#[derive(Debug, Snafu)]
pub enum GetGuildAndVoiceChannelIdError {
    /// this command was not used inside a guild (Discord server)
    NotInGuild,

    /// there is no user who invoked this command
    NoUser,

    /// the bot is not in a voice chat in this guild
    BotNotInVC,

    /// the user is not in a voice chat with the bot in this guild
    UserNotInVCWithBot,
}

#[tracing::instrument]
pub fn get_user_and_guild_and_voice_channel_id(
    bot_user_id: Id<UserMarker>,
    interaction: &Interaction,
    vcs: &VCs,
) -> Result<(Id<GuildMarker>, Id<ChannelMarker>), GetGuildAndVoiceChannelIdError> {
    let guild_id = interaction.guild_id.context(NotInGuildSnafu)?;

    let user_id = interaction
        .member
        .as_ref()
        .and_then(|member| member.user.as_ref().map(|user| user.id))
        .context(NoUserSnafu)?;

    let &bot_voice_channel_id = vcs
        .get(&guild_id)
        .context(BotNotInVCSnafu)?
        .get_left_for(&bot_user_id)
        .context(BotNotInVCSnafu)?;

    let &user_voice_channel_id = vcs
        .get(&guild_id)
        .context(UserNotInVCWithBotSnafu)?
        .get_left_for(&user_id)
        .context(UserNotInVCWithBotSnafu)?;

    if user_voice_channel_id != bot_voice_channel_id {
        return Err(GetGuildAndVoiceChannelIdError::UserNotInVCWithBot);
    }

    Ok((guild_id, bot_voice_channel_id))
}

fn get_guild_and_vc_error_to_embed(error: GetGuildAndVoiceChannelIdError) -> Embed {
    match error {
        GetGuildAndVoiceChannelIdError::NotInGuild => {
            EmbedBuilder::new().title("Use this in a server").description("This bot can't tell which VC to leave if the command is used outside of a server (you might've used it in a DM?).").validate().unwrap().build()
        },
        GetGuildAndVoiceChannelIdError::NoUser => {
            EmbedBuilder::new().title("Not invoked by a user").description("This command works by joining the same VC as the user, but this bot didn't receive any user data. So did no user invoke it?! (This error should be impossible!)").validate().unwrap().build()
        },
        GetGuildAndVoiceChannelIdError::BotNotInVC => {
            EmbedBuilder::new().title("Not in a VC").description("This bot can't leave VC if it isn't in one in this server.").validate().unwrap().build()
        },
        GetGuildAndVoiceChannelIdError::UserNotInVCWithBot => {
            EmbedBuilder::new().title("Not in a VC with the Bot").description("You have to be in the VC with the bot to make it leave (to prevent griefing and abuse).").validate().unwrap().build()
        },
    }
}

#[tracing::instrument]
pub async fn handle(state: State, interaction: Interaction) {
    let guild_and_voice_channel_id_result = {
        get_user_and_guild_and_voice_channel_id(
            state.discord_user_id,
            &interaction,
            &state.vcs_sender.borrow(),
        )
    };
    let (guild_id, voice_channel_id) = match guild_and_voice_channel_id_result {
        Ok((guild_id, voice_channel_id)) => (guild_id, voice_channel_id),
        Err(error) => {
            state
                .discord_client
                .interaction(state.discord_application_id)
                .create_response(
                    interaction.id,
                    &interaction.token,
                    &InteractionResponse {
                        kind: InteractionResponseType::ChannelMessageWithSource,
                        data: Some(
                            InteractionResponseDataBuilder::new()
                                .embeds([get_guild_and_vc_error_to_embed(error)])
                                .flags(MessageFlags::EPHEMERAL)
                                .build(),
                        ),
                    },
                )
                .await
                .expect("TODO");

            return;
        }
    };

    state.songbird.leave(guild_id).await.expect("TODO");

    tracing::error!("TODO: successfully left the call");

    let channel_mention = format!("<#{voice_channel_id}>");

    state
        .discord_client
        .interaction(state.discord_application_id)
        .create_response(interaction.id, &interaction.token,
                &InteractionResponse {
                    kind: InteractionResponseType::ChannelMessageWithSource,
                    data: Some(
                        InteractionResponseDataBuilder::new()
                            .embeds([
                                EmbedBuilder::new()
                                    .title("Left VC")
                                    .description(format!(
                                        "This bot left {channel_mention} (and is thereby unable to record anymore)."
                                    ))
                                    .validate()
                                    .unwrap()
                                    .build()
                            ])
                            .flags(MessageFlags::EPHEMERAL)
                            .build(),
                    ),
                },)
        .await
        .expect("TODO");
}