use serenity::all::{ChannelId, GuildId};
use serenity::async_trait;

use songbird::events::{Event, EventContext, EventHandler as VoiceEventHandler};
use songbird::TrackEvent;

use crate::{types::{Context, Error}, util::utilities::get_channel_by_name};

/// Returns either voice channel to which the user is currently connected to or the one passed via name
async fn get_voice_channel(ctx: &Context<'_>, name: Option<String>) -> Result<ChannelId, String> {
    if name.is_none() || name.as_ref().is_some_and(|n| n.is_empty()) {
        match ctx.guild().and_then(|guild|
            guild.voice_states.get(&ctx.author().id).and_then(|voice_state|
                voice_state.channel_id
        ) 
        ) {
            Some(c) => Ok(c),
            None => Err("You must be in a voice channel or specify explicit voice channel by name".to_string())
        }
    }
    else {
        match ctx.guild().and_then(|guild|
            get_channel_by_name(guild, name.unwrap()) 
        ) {
            Some(c) => Ok(c),
            None => Err("Channel with this name does not exist".to_string())
        }
    }
}

struct TrackErrorNotifier;

#[async_trait]
impl VoiceEventHandler for TrackErrorNotifier {
    async fn act(&self, ctx: &EventContext<'_>) -> Option<Event> {
        if let EventContext::Track(track_list) = ctx {
            for (state, handle) in *track_list {
                println!(
                    "Track {:?} encountered an error: {:?}",
                    handle.uuid(),
                    state.playing
                );
            }
        }

        None
    }
}

pub async fn connect(ctx: &Context<'_>, guild_id: GuildId, channel: Option<String>) -> Result<(), Error> {
    let voice_channel = get_voice_channel(&ctx, channel).await?;

    let manager = songbird::get(ctx.serenity_context())
        .await
        .expect("Songbird Voice client placed in at initialisation.")
        .clone();

    if let Ok(handler_lock) = manager.join(guild_id, voice_channel).await {
        let mut handler = handler_lock.lock().await;
        handler.add_global_event(TrackEvent::Error.into(), TrackErrorNotifier);
    }

    Ok(())
}

pub async fn autocomplete_channel(
    ctx: Context<'_>,
    _partial: &str,
) -> Vec<String> {

    use crate::util::utilities::get_vc_names;
    match ctx.guild() {
        Some(guild) => get_vc_names(guild),
        None => [].to_vec()
    }
}