use log::info;
use serenity::{async_trait, model::prelude::*, prelude::*};
use tokio::sync::mpsc;

use crate::{
    channels::ChannelReference,
    message_ast::{self, format_discord},
    messages::{
        DeletedMessage, EditedMessage, MessageAuthor, MessageEvent, MessageReference, SentMessage,
    },
};

pub use serenity::client::Context;
pub use serenity::model::id::{ChannelId, MessageId};

impl From<&Message> for MessageReference {
    fn from(message: &Message) -> Self {
        Self::Discord(message.channel_id.0, message.id.0)
    }
}

struct DiscordHandler {
    ctx_tx: mpsc::UnboundedSender<Context>,
    event_tx: mpsc::UnboundedSender<MessageEvent>,
}

async fn get_message_author(ctx: &Context, message: &Message) -> MessageAuthor {
    async fn user_tag_color(ctx: &Context, message: &Message) -> Option<String> {
        Some(
            message
                .member(ctx)
                .await
                .ok()?
                .colour(ctx)
                .await?
                .hex()
                .to_ascii_lowercase(),
        )
    }

    MessageAuthor {
        display_name: message
            .author_nick(ctx)
            .await
            .unwrap_or_else(|| message.author.name.clone()),
        avatar_url: message
            .author
            .static_avatar_url()
            .unwrap_or_else(|| message.author.default_avatar_url()),
        service_name: "discord".to_string(),
        display_color: user_tag_color(ctx, message).await,
    }
}

#[async_trait]
impl EventHandler for DiscordHandler {
    async fn ready(&self, ctx: Context, _ready: Ready) {
        let _ = self.ctx_tx.send(ctx);
        info!("Discord ready!");
    }

    async fn message(&self, ctx: Context, message: Message) {
        if let Some(target) = message.content.strip_prefix("phoebe!link ") {
            if message
                .member(&ctx)
                .await
                .unwrap()
                .roles(&ctx)
                .await
                .unwrap()
                .iter()
                .any(|r| r.name == "Phoebe")
            {
                let _ = self.event_tx.send(MessageEvent::AdminLinkChannels(vec![
                    ChannelReference::Discord(message.channel_id.0),
                    ChannelReference::Matrix(target.to_string()),
                ]));

                message.reply(&ctx, "Linking with matrix.").await.unwrap();
                return;
            }
        }

        let message_ref = MessageReference::from(&message);

        let content = discord_message_format::parse(&message.content);
        let content = message_ast::convert_discord(&content);

        let replies_to = message
            .referenced_message
            .as_ref()
            .map(|m| MessageReference::from(m.as_ref()));

        let _ = self.event_tx.send(MessageEvent::Send(Box::new(SentMessage {
            source: message_ref,
            content,
            author: get_message_author(&ctx, &message).await,
            replies_to,
        })));
    }

    async fn message_update(
        &self,
        ctx: Context,
        _old_if_available: Option<Message>,
        new: Option<Message>,
        event: MessageUpdateEvent,
    ) {
        if let Ok(new_message) = {
            if let Some(m) = new {
                Ok(m)
            } else {
                event.channel_id.message(&ctx, event.id).await
            }
        } {
            let message_ref = MessageReference::from(&new_message);

            let content = discord_message_format::parse(&new_message.content);
            let content = message_ast::convert_discord(&content);

            let _ = self
                .event_tx
                .send(MessageEvent::Edit(Box::new(EditedMessage {
                    replacing: message_ref,
                    content,
                    author: get_message_author(&ctx, &new_message).await,
                })));
        }
    }

    async fn message_delete(
        &self,
        _ctx: Context,
        channel_id: ChannelId,
        deleted_message_id: MessageId,
        _guild_id: Option<GuildId>,
    ) {
        let message_ref = MessageReference::Discord(channel_id.0, deleted_message_id.0);
        let _ = self
            .event_tx
            .send(MessageEvent::Delete(Box::new(DeletedMessage {
                reference: message_ref,
            })));
    }
}

async fn get_webhook_for_channel(discord_ctx: &Context, channel: &ChannelId) -> Option<Webhook> {
    if let Ok(webhooks) = channel.webhooks(discord_ctx).await {
        for webhook in webhooks {
            if matches!(webhook.name.as_deref(), Some("phoebe")) {
                return Some(webhook);
            }
        }
    }

    None
}

async fn get_or_create_webhook_for_channel(
    discord_ctx: &Context,
    channel: &ChannelId,
) -> Option<Webhook> {
    if let Some(webhook) = get_webhook_for_channel(discord_ctx, channel).await {
        return Some(webhook);
    }

    if let Ok(webhook) = channel.create_webhook(discord_ctx, "phoebe").await {
        return Some(webhook);
    }

    None
}

async fn create_webhook_reply_embeds(
    discord_ctx: &Context,
    reply: Option<(u64, u64)>,
) -> Vec<serde_json::Value> {
    if let Some((channel_id, message_id)) = reply {
        if let Ok(replied_message) = ChannelId(channel_id)
            .message(discord_ctx, MessageId(message_id))
            .await
        {
            let replied_author_name = format!(
                "{} ↩️",
                replied_message
                    .author_nick(discord_ctx)
                    .await
                    .as_ref()
                    .unwrap_or(&replied_message.author.name)
            );

            let reply_description = format!(
                "**[Reply to:]({})**\n{}",
                replied_message.id.link(
                    ChannelId(channel_id),
                    discord_ctx
                        .cache
                        .guild_channel(channel_id)
                        .await
                        .map(|gc| gc.guild_id)
                ),
                &replied_message.content
            );

            return vec![Embed::fake(|e| {
                e.author(|a| {
                    a.icon_url(
                        &replied_message
                            .author
                            .static_avatar_url()
                            .unwrap_or_else(|| replied_message.author.default_avatar_url()),
                    )
                    .name(replied_author_name)
                })
                .description(reply_description)
            })];
        }
    }

    vec![]
}

pub async fn forward_to_discord(
    discord_ctx: &Context,
    channel: ChannelId,
    message: &SentMessage,
    reply: Option<(u64, u64)>,
) -> Option<MessageReference> {
    if let Some(webhook) = get_or_create_webhook_for_channel(discord_ctx, &channel).await {
        let reply_embeds = create_webhook_reply_embeds(discord_ctx, reply).await;

        return webhook
            .execute(discord_ctx, true, |w| {
                w.content(format_discord(&message.content))
                    .username(format!(
                        "{} ({})",
                        &message.author.display_name, &message.author.service_name
                    ))
                    .avatar_url(&message.author.avatar_url)
                    .embeds(reply_embeds)
            })
            .await
            .ok()
            .flatten()
            .as_ref()
            .map(MessageReference::from);
    }

    channel
        .send_message(discord_ctx, |m| {
            let content = format_discord(&message.content);

            if let Some((channel_id, message_id)) = reply {
                m.content(&content)
                    .reference_message((ChannelId(channel_id), MessageId(message_id)))
            } else {
                m.content(&content)
            }
        })
        .await
        .as_ref()
        .ok()
        .map(MessageReference::from)
}

pub async fn edit_on_discord(
    discord_ctx: &Context,
    channel_id: ChannelId,
    message_id: MessageId,
    message: &EditedMessage,
) -> Option<MessageReference> {
    if let Some(webhook) = get_or_create_webhook_for_channel(discord_ctx, &channel_id).await {
        return webhook
            .edit_message(discord_ctx, message_id, |w| {
                w.content(format_discord(&message.content))
            })
            .await
            .as_ref()
            .ok()
            .map(MessageReference::from);
    }

    channel_id
        .edit_message(&discord_ctx, &message_id, |m| {
            m.content(format_discord(&message.content))
        })
        .await
        .as_ref()
        .ok()
        .map(MessageReference::from)
}

pub async fn delete_on_discord(
    discord_ctx: &Context,
    channel_id: ChannelId,
    message_id: MessageId,
    _message: &DeletedMessage,
) -> bool {
    if let Some(webhook) = get_or_create_webhook_for_channel(discord_ctx, &channel_id).await {
        return webhook
            .delete_message(discord_ctx, message_id)
            .await
            .is_ok();
    }

    channel_id
        .delete_message(&discord_ctx, &message_id)
        .await
        .is_ok()
}

pub async fn create_discord_client(
    ctx_tx: mpsc::UnboundedSender<Context>,
    message_tx: mpsc::UnboundedSender<MessageEvent>,
    token: &str,
) -> Client {
    let handler = DiscordHandler {
        ctx_tx,
        event_tx: message_tx,
    };

    info!("Discord logging in…");
    let client = Client::builder(token)
        .event_handler(handler)
        .await
        .expect("Failed to create discord client");
    info!("Discord starting…");

    client
}