use crate::{util, Bot};
use anyhow::Context;
use log::{error, info, warn};
use matrix_sdk::{
    room::{Joined, Room},
    ruma::{
        api::client::r0::media::create_content,
        events::room::{
            message::{
                FileInfo,
                FileMessageEventContent,
                ImageMessageEventContent,
                MessageType,
                RoomMessageEventContent,
                VideoInfo,
                VideoMessageEventContent,
            },
            ImageInfo,
        },
        MxcUri,
        UInt,
    },
};
use mime::Mime;
use serde::{Deserialize, Serialize};
use std::{io::Cursor, sync::atomic::Ordering};

/// A meme stored in the cache database
#[derive(Debug, Deserialize, Serialize)]
struct CachedMeme {
    /// mxc url of the meme
    mxc: Box<MxcUri>,
    /// MIME type of the meme
    #[serde(with = "util::mime_serialize")]
    mime: Mime,
    /// file size of the meme
    size: UInt,
    /// file name of the meme
    meme_name: String,
}

impl CachedMeme {
    fn into_message_type(self) -> MessageType {
        let Self {
            mxc,
            mime,
            size,
            meme_name,
        } = self;

        match mime.type_() {
            mime::IMAGE => MessageType::Image(ImageMessageEventContent::plain(
                meme_name,
                mxc,
                Some(Box::new({
                    let mut info = ImageInfo::new();
                    info.mimetype = Some(mime.to_string());
                    info.size = Some(size);
                    info
                })),
            )),
            mime::VIDEO => MessageType::Video(VideoMessageEventContent::plain(
                meme_name,
                mxc,
                Some(Box::new({
                    let mut info = VideoInfo::new();
                    info.mimetype = Some(mime.to_string());
                    info.size = Some(size);
                    info
                })),
            )),
            _ => MessageType::File(FileMessageEventContent::plain(
                meme_name,
                mxc,
                Some(Box::new({
                    let mut info = FileInfo::new();
                    info.mimetype = Some(mime.to_string());
                    info.size = Some(size);
                    info
                })),
            )),
        }
    }
}

pub async fn on_msg(msg: &str, room: Room, bot: &Bot) -> anyhow::Result<()> {
    let room = match room {
        Room::Joined(room) => room,
        _ => {
            warn!(
                "Received message '{}' in room {:?} that's not joined",
                msg,
                room.name()
            );
            return Ok(());
        },
    };

    if let Some(ref sendmeme_cmd) = bot.config.sendmeme_command {
        let mut words = msg.split(' ');
        if words.next() == Some(sendmeme_cmd) {
            if let Some(id) = words.next() {
                let id = if let Ok(id) = id.parse::<u32>() {
                    id
                } else {
                    room.send(RoomMessageEventContent::text_plain("Invalid ID!"), None)
                        .await?;
                    return Ok(());
                };

                bot.jm_client.write().await.clear_cache().await;
                bot.meme_count.store(0, Ordering::SeqCst);
                cache_send_meme(id, bot, room).await?;
                return Ok(());
            }
        }
    }

    for meme in &bot.config.memes {
        if meme.matches(msg) {
            if let Some(id) = meme.get_id(bot).await? {
                cache_send_meme(id, bot, room).await?;
            }
            break;
        }
    }

    Ok(())
}

async fn cache_send_meme(meme_id: u32, bot: &Bot, room: Joined) -> anyhow::Result<()> {
    bot.meme_count.fetch_add(1, Ordering::SeqCst);
    let memes = bot.jm_client.read().await.get_memes().await?;
    let meme = memes
        .iter()
        .find(|m| m.id.parse::<u32>().ok() == Some(meme_id))
        .cloned();

    if let Some(meme) = meme {
        if let Some(ivec) = bot.memecache.get(meme_id.to_be_bytes())? {
            let cached = bincode::deserialize::<CachedMeme>(&ivec)?;
            send_meme(&room, cached).await?;
        } else {
            info!("Meme {} not found in cache, uploading...", meme_id);
            let resp = bot
                .jm_client
                .read()
                .await
                .http
                .get(&meme.link)
                .send()
                .await
                .context("error downloading meme")?;
            let resp = resp.bytes().await?;

            if let Some(mime) = mime_guess::from_path(&meme.link).first() {
                let size = resp.len();
                let create_content::Response { content_uri, .. } =
                    bot.client.upload(&mime, &mut Cursor::new(resp)).await?;

                let cached = CachedMeme {
                    mxc: content_uri,
                    mime,
                    size: UInt::new(size as u64)
                        .context("Meme has file size over allowed limit!")?,
                    meme_name: meme
                        .link
                        .split('/')
                        .last()
                        .unwrap_or(&meme.link)
                        .to_string(),
                };

                bot.memecache
                    .insert(meme_id.to_be_bytes(), bincode::serialize(&cached)?)?;

                send_meme(&room, cached).await?;
                // we do this after we have responded, in order to not delay the response
                if bot.meme_count.load(Ordering::SeqCst) >= bot.config.clear_cache_threshold {
                    let mut client = bot.jm_client.write().await;
                    bot.meme_count.store(0, Ordering::SeqCst);
                    client.clear_cache().await;
                    // memes requested but not used, but they will be cached
                    client.get_memes().await?;
                }
            } else {
                error!(
                    "Couldn't guess MIME type of meme '{}', skipping.",
                    &meme.link
                );
            }
        }
    } else {
        room.send(
            RoomMessageEventContent::text_plain(format!("No meme with id '{}'", meme_id)),
            None,
        )
        .await?;
    }

    Ok(())
}

async fn send_meme(room: &Joined, cached: CachedMeme) -> anyhow::Result<()> {
    let msg_ty = cached.into_message_type();
    room.send(RoomMessageEventContent::new(msg_ty), None)
        .await
        .context("Failed to send meme")?;

    Ok(())
}