use chrono::Duration;
use grate::tracing;
use lazy_static::lazy_static;
use poise::FrameworkError;
use regex::{
    Match,
    Regex,
};
use serenity::{
    all::{
        CreateMessage,
        GuildId,
        GuildRef,
        Message,
        Reaction,
        ReactionType,
        VoiceState,
    },
    client::Context,
    model::{
        id::{
            ChannelId,
            MessageId,
        },
        permissions::Permissions,
    },
};
use std::{
    collections::HashMap,
    process::Stdio,
};
use tap::Pipe;
use url::Url;

use crate::{
    CONFIG,
    PoiseContext,
    commands::playback::songbird,
};

mod rest_vec;

#[cfg(windows)]
pub mod windows;

pub use rest_vec::*;

pub async fn currently_playing(ctx: PoiseContext<'_>) -> bool {
    let (_sb, call) = songbird(ctx).await.expect("no songbird");

    let call = call.lock().await;
    call.queue().current().is_some()
}

pub async fn users_listening(ctx: PoiseContext<'_>) -> anyhow::Result<bool> {
    let Some(channel) = best_voice_channel(ctx) else {
        return Ok(false);
    };

    let Some(guild) = ctx.guild() else {
        return Ok(false);
    };

    guild.voice_states.iter().any(|(_, state)| state.channel_id == Some(channel)).pipe(Ok)
}

#[inline]
pub fn msg<U, E>(ctx: poise::Context<'_, U, E>) -> Option<&Message> {
    match ctx {
        poise::Context::Prefix(poise::PrefixContext {
            msg,
            ..
        }) => Some(msg),
        _ => None,
    }
}

#[inline]
pub fn err_msg<'a, U, E>(err: &'a FrameworkError<U, E>) -> Option<&'a Message> {
    use FrameworkError::*;

    if let Some(ctx) = err.ctx() {
        return msg(ctx);
    }

    match *err {
        UnknownCommand {
            msg,
            ..
        }
        | DynamicPrefix {
            msg,
            ..
        } => Some(msg),
        _ => None,
    }
}

#[inline]
pub fn tts<U, E>(ctx: poise::Context<'_, U, E>) -> Option<bool> {
    msg(ctx).map(|msg| msg.tts)
}

#[inline]
pub fn unwrap_tts<U, E>(ctx: poise::Context<'_, U, E>) -> bool {
    tts(ctx).unwrap_or(false)
}

#[inline]
pub async fn volume(ctx: PoiseContext<'_>) -> f64 {
    let Some(guild_id) = ctx.guild_id() else {
        return 1.;
    };

    let data = ctx.serenity_context().data.read().await;
    let vol = data.get::<crate::bot::VolumeKey>().unwrap();

    vol.get(&guild_id).map(|g| *g).unwrap_or(1.)
}

#[inline]
pub async fn send(
    ctx: &Context,
    channel: ChannelId,
    text: impl AsRef<str>,
    tts: bool,
) -> anyhow::Result<()> {
    send_result(ctx, channel, text, tts).await.map(|_| ())
}

#[inline]
pub async fn reply<U, E>(
    ctx: poise::Context<'_, U, E>,
    text: impl AsRef<str>,
) -> anyhow::Result<()> {
    let msg = msg(ctx).ok_or_else(|| anyhow::anyhow!("couldn't find referenced message"))?;

    let reply = CreateMessage::new()
        .reference_message(msg)
        .tts(msg.tts)
        .content(text.as_ref())
        .allowed_mentions(Default::default());

    let channel = ctx.guild_channel().await.ok_or_else(|| anyhow::anyhow!("not in a guild"))?;
    channel.send_message(ctx.http(), reply).await?;

    Ok(())
}

#[inline]
pub async fn react(
    ctx: PoiseContext<'_>,
    react: impl Into<ReactionType> + Send,
) -> anyhow::Result<Reaction> {
    msg(ctx)
        .ok_or_else(|| anyhow::anyhow!("elp"))?
        .react(ctx, react)
        .await
        .map_err(anyhow::Error::from)
}

#[inline]
pub async fn unreact(
    ctx: PoiseContext<'_>,
    react: impl Into<ReactionType> + Send,
) -> anyhow::Result<()> {
    msg(ctx).ok_or_else(|| anyhow::anyhow!("elp"))?.delete_reaction(ctx, None, react).await?;
    Ok(())
}

#[inline]
pub fn guild_id(ctx: PoiseContext<'_>) -> anyhow::Result<GuildId> {
    ctx.guild_id().ok_or_else(|| anyhow::anyhow!("not in guild"))
}

#[inline]
pub fn guild(ctx: PoiseContext<'_>) -> anyhow::Result<GuildRef<'_>> {
    ctx.guild().ok_or_else(|| anyhow::anyhow!("not in guild"))
}

#[inline]
pub fn author_voice_state(ctx: PoiseContext<'_>) -> Option<(VoiceState, GuildRef<'_>)> {
    let guild = ctx.guild()?;
    let caller_voice = guild.voice_states.get(&ctx.author().id)?.clone();

    Some((caller_voice, guild))
}

#[inline]
pub fn author_voice_channel(ctx: PoiseContext<'_>) -> Option<ChannelId> {
    let (vs, _guild) = author_voice_state(ctx)?;
    vs.channel_id
}

pub fn voice_states_by_channel(ctx: PoiseContext<'_>) -> HashMap<ChannelId, Vec<VoiceState>> {
    let Some(guild) = ctx.guild() else {
        return Default::default();
    };

    guild
        .voice_states
        .values()
        .cloned()
        .filter_map(|x| {
            let id = x.channel_id?;
            Some((id, x))
        })
        .fold(HashMap::new(), |mut acc, (id, state)| {
            acc.entry(id).or_insert_with(Vec::new).push(state);

            acc
        })
}

/// Select the most relevant voice channel for a given poise context.
///
/// - If the message's author is in a voice channel, use that.
/// - If not, pick the most populated channel (channel age tiebreaks).
pub fn best_voice_channel(ctx: PoiseContext<'_>) -> Option<ChannelId> {
    if let Some(channel) = author_voice_channel(ctx) {
        return Some(channel);
    }

    let voice_states = voice_states_by_channel(ctx);
    let max_pop = voice_states.values().map(|states| states.len()).max();

    let matching_channels = voice_states
        .iter()
        .filter_map(|(&channel, state)| {
            if state.len() == max_pop? {
                return Some(channel);
            }

            None
        })
        .collect::<Vec<_>>();

    if matching_channels.len() == 1 {
        return matching_channels.first().cloned();
    }

    matching_channels.into_iter().min()
}

pub async fn send_result(
    ctx: &Context,
    channel: ChannelId,
    text: impl AsRef<str>,
    tts: bool,
) -> anyhow::Result<MessageId> {
    let text = text.as_ref();
    tracing::debug!(text, %channel, tts, "sending message");

    let result = channel
        .send_message(
            ctx,
            CreateMessage::default().content(text).tts(tts).allowed_mentions(Default::default()),
        )
        .await?;
    Ok(result.id)
}

lazy_static! {
    pub static ref REQUIRED_PERMS: Permissions = Permissions::EMBED_LINKS
        | Permissions::VIEW_CHANNEL
        | Permissions::ADD_REACTIONS
        | Permissions::READ_MESSAGE_HISTORY // need this in order to delete message reactions
        | Permissions::SEND_MESSAGES
        | Permissions::CONNECT
        | Permissions::SPEAK
        | Permissions::ATTACH_FILES
        | Permissions::SEND_MESSAGES_IN_THREADS;
    pub static ref DESIRED_PERMS: Permissions = *REQUIRED_PERMS
        | Permissions::USE_EXTERNAL_EMOJIS
        | Permissions::CHANGE_NICKNAME
        | Permissions::SEND_TTS_MESSAGES;
}

lazy_static! {
    pub static ref OAUTH_URL: Url = Url::parse(&format!(
        "https://discordapp.com/api/oauth2/authorize?scope=bot&permissions={}&client_id={}",
        DESIRED_PERMS.bits(),
        CONFIG.discord.auth.client_id,
    ))
    .unwrap();
}

pub async fn ytdl_url(uri: &str) -> anyhow::Result<String> {
    use serde_json::Value;
    use tokio::process::Command;

    let args = [
        "-f",
        "webm[abr>0]/bestaudio/best",
        "--no-playlist",
        "--print-json",
        "--skip-download",
        uri,
    ];

    tracing::debug!(uri, "downloading info");

    let mut command = Command::new(&*crate::config::YTDL_COMMAND);
    command.args(args).stdin(Stdio::null());

    tracing::debug!(?command, "running command");

    let out = command.output().await?;

    if !out.status.success() {
        return Err(anyhow::anyhow!("running ytdl: {out:?}"));
    }

    let value = serde_json::from_reader(&out.stdout[..])?;
    let mut obj = match value {
        Value::Object(obj) => obj,
        other => return Err(anyhow::anyhow!("ytdl output not object: {other:?}")),
    };

    match obj.remove("url") {
        Some(v) => match v {
            Value::String(uri) => Ok(uri),
            other => Err(anyhow::anyhow!("url not string: {other:?}")),
        },
        None => Err(anyhow::anyhow!("no url")),
    }
}
pub fn parse_times<A: AsRef<str>>(s: A) -> (Option<Duration>, Option<Duration>) {
    lazy_static! {
        static ref START_REGEX: Regex =
            Regex::new(r"(?:start|begin(?:ning)?)\s*=?\s*(?:(?P<hours>\d+)h\s?)?(?:(?P<minutes>\d+)m\s?)?(?:(?P<seconds>\d+)s?)?").unwrap();

        static ref DUR_REGEX: Regex =
            Regex::new(r"dur(?:ation)?\s*=?\s*(?:(?P<hours>\d+)h\s?)?(?:(?P<minutes>\d+)m\s?)?(?:(?P<seconds>\d+)s?)?").unwrap();

        static ref END_REGEX: Regex =
            Regex::new(r"(?:end|term(?:inate|ination)?)\s*=?\s*(?:(?P<hours>\d+)h\s?)?(?:(?P<minutes>\d+)m\s?)?(?:(?P<seconds>\d+)s?)?").unwrap();
    }

    fn parse_match(m: Option<Match>) -> u64 {
        m.and_then(|s| s.as_str().parse::<u64>().ok()).unwrap_or(0)
    }

    fn parse_captures<B: AsRef<str>>(r: &Regex, s: B) -> Option<Duration> {
        r.captures(s.as_ref()).map(|capt| {
            let hours = parse_match(capt.name("hours"));
            let minutes = parse_match(capt.name("minutes"));
            let seconds = parse_match(capt.name("seconds"));

            let result = Duration::hours(hours as i64)
                + Duration::minutes(minutes as i64)
                + Duration::seconds(seconds as i64);

            assert!(result >= Duration::zero());

            result
        })
    }

    let start_time = parse_captures(&START_REGEX, &s);
    let dur = parse_captures(&DUR_REGEX, &s);
    let end_time = parse_captures(&END_REGEX, s)
        .or_else(|| start_time.and_then(|start| dur.map(|d| start + d)));

    (start_time, end_time)
}