use crate::comms::BusMessage;
use crate::db::{DbPerson, DbPersonRelay, DbRelay};
use crate::error::Error;
use crate::feed_event::FeedEvent;
use crate::settings::Settings;
use nostr_types::{Event, EventKind, Id, Metadata, PublicKey, PublicKeyHex, Tag, Unixtime, Url};
use rusqlite::Connection;
use std::collections::HashMap;
use std::sync::atomic::AtomicBool;
use tokio::sync::{broadcast, mpsc, Mutex};
use tracing::{trace, warn};

/// Only one of these is ever created, via lazy_static!, and represents
/// global state for the rust application
pub struct Globals {
    /// This is our connection to SQLite. Only one thread at a time.
    pub db: Mutex<Option<Connection>>,

    /// This is a broadcast channel. All Minions should listen on it.
    /// To create a receiver, just run .subscribe() on it.
    pub to_minions: broadcast::Sender<BusMessage>,

    /// This is a mpsc channel. The Overlord listens on it.
    /// To create a sender, just clone() it.
    pub to_overlord: mpsc::UnboundedSender<BusMessage>,

    /// This is ephemeral. It is filled during lazy_static initialization,
    /// and stolen away when the Overlord is created.
    pub from_minions: Mutex<Option<mpsc::UnboundedReceiver<BusMessage>>>,

    /// All nostr event related data, keyed by the event Id
    pub feed_events: Mutex<HashMap<Id, FeedEvent>>,

    /// Desired events, referred to by others, with possible URLs where we can
    /// get them.  We may already have these, but if not we should ask for them.
    pub desired_events: Mutex<HashMap<Id, Vec<Url>>>,

    /// All nostr people records currently loaded into memory, keyed by pubkey
    pub people: Mutex<HashMap<PublicKey, DbPerson>>,

    /// Whether or not we have a saved private key and need the password to unlock it
    #[allow(dead_code)]
    pub need_password: AtomicBool,

    /// Settings
    pub settings: Mutex<Settings>,
}

lazy_static! {
    pub static ref GLOBALS: Globals = {

        // Setup a communications channel from the Overlord to the Minions.
        let (to_minions, _) = broadcast::channel(16);

        // Setup a communications channel from the Minions to the Overlord.
        let (to_overlord, from_minions) = mpsc::unbounded_channel();

        Globals {
            db: Mutex::new(None),
            to_minions,
            to_overlord,
            from_minions: Mutex::new(Some(from_minions)),
            feed_events: Mutex::new(HashMap::new()),
            desired_events: Mutex::new(HashMap::new()),
            people: Mutex::new(HashMap::new()),
            need_password: AtomicBool::new(false),
            settings: Mutex::new(Settings::default()),
        }
    };
}

#[allow(dead_code)]
pub async fn get_feed(threaded: bool) -> Vec<Id> {
    let feed: Vec<FeedEvent> = GLOBALS
        .feed_events
        .lock()
        .await
        .iter()
        .map(|(_, e)| e)
        .filter(|e| e.event.is_some() && e.event.as_ref().unwrap().kind == EventKind::TextNote)
        .filter(|e| {
            if threaded {
                e.in_reply_to.is_none()
            } else {
                true
            }
        }) // only root events
        .cloned()
        .collect();

    sort_feed(feed, threaded)
}

#[allow(dead_code)]
pub fn blocking_get_feed(threaded: bool) -> Vec<Id> {
    let feed: Vec<FeedEvent> = GLOBALS
        .feed_events
        .blocking_lock()
        .iter()
        .map(|(_, e)| e)
        .filter(|e| e.event.is_some() && e.event.as_ref().unwrap().kind == EventKind::TextNote)
        .filter(|e| {
            if threaded {
                e.in_reply_to.is_none()
            } else {
                true
            }
        }) // only root events
        .cloned()
        .collect();

    sort_feed(feed, threaded)
}

fn sort_feed(mut feed: Vec<FeedEvent>, threaded: bool) -> Vec<Id> {
    if threaded {
        feed.sort_unstable_by(|a, b| b.last_reply_at.cmp(&a.last_reply_at));
    } else {
        feed.sort_unstable_by(|a, b| {
            if a.event.is_some() && b.event.is_some() {
                b.event
                    .as_ref()
                    .unwrap()
                    .created_at
                    .cmp(&a.event.as_ref().unwrap().created_at)
            } else if a.event.is_some() {
                std::cmp::Ordering::Greater
            } else if b.event.is_some() {
                std::cmp::Ordering::Less
            } else {
                std::cmp::Ordering::Equal
            }
        });
    }

    feed.iter().map(|e| e.id).collect()
}

pub async fn add_event(event: &Event) -> Result<(), Error> {
    // Insert the event
    insert_event(event).await;

    // Deal with 'e' tags on kind 1 5 and 7 (they have no meaning elsewhere)
    // we dont support EncryptedDirectMessage
    if event.kind == EventKind::TextNote || event.kind == EventKind::Reaction {
        let mut root: Option<Id> = None;
        let mut reply: Option<Id> = None;
        let mut refer: Vec<Id> = Vec::new(); // this is not used yet

        // Count the 'e' tags first
        let count = event
            .tags
            .iter()
            .filter(|t| matches!(t, Tag::Event { .. }))
            .count();

        for (n, tag) in event
            .tags
            .iter()
            .filter(|t| matches!(t, Tag::Event { .. }))
            .enumerate()
        {
            if let Tag::Event {
                id,
                recommended_relay_url,
                marker,
            } = tag
            {
                // Add the id to desired events list
                {
                    let mut desired_events = GLOBALS.desired_events.lock().await;
                    desired_events
                        .entry(*id)
                        .and_modify(|urls| {
                            if let Some(url) = recommended_relay_url {
                                urls.push(url.to_owned());
                            }
                        })
                        .or_insert_with(|| {
                            if let Some(url) = recommended_relay_url {
                                vec![url.to_owned()]
                            } else {
                                vec![]
                            }
                        });
                }

                // Sort out root, reply and refer
                if marker.is_some() {
                    if marker.as_ref().unwrap() == "root" {
                        root = Some(*id);
                    } else if marker.as_ref().unwrap() == "reply" {
                        reply = Some(*id);
                    } else {
                        warn!("Unknown event tag marker: {}", marker.as_ref().unwrap());
                    }
                } else if n == count - 1 {
                    reply = Some(*id);
                } else if n == 0 {
                    root = Some(*id);
                } else {
                    refer.push(*id);
                }
            }
        }

        if let Some(id) = reply {
            // Mark our event in reply to
            update_feed_event(event.id, |this_event| {
                this_event.in_reply_to = Some(id);
            })
            .await;

            // Mark the parent event as having us as a reply
            update_feed_event(id, |parent_event| {
                parent_event.replies.push(event.id);
            })
            .await;

            // Get our last_reply_at for propogating upwards
            let mut last_reply_at = event.created_at.0;

            // Update the last_reply_at all the way up the chain
            let mut xid = id;
            loop {
                let mut in_reply_to: Option<Id> = None;
                update_feed_event(xid, |ancestor_event| {
                    if let Some(other) = ancestor_event.last_reply_at {
                        last_reply_at = other.max(last_reply_at);
                        ancestor_event.last_reply_at = Some(last_reply_at);
                    } else {
                        ancestor_event.last_reply_at = Some(last_reply_at);
                    }
                    in_reply_to = ancestor_event.in_reply_to; // next up the chain
                })
                .await;

                xid = match in_reply_to {
                    Some(ref id) => *id,
                    None => break,
                }
            }
        }

        // We ignore 'root' and 'refer'.
        if let Some(id) = root {
            trace!("event root = {}", id.as_hex_string());
        }
    }

    // Some kinds seen in the wild:
    //    nonce, p, e, t, client, content-warning,
    //    subject, h, i, nostril, r, hashtag
    for tag in event.tags.iter() {
        // Get some metadata from tags that could apply to multiple
        // kinds of events

        match tag {
            Tag::Event {
                id,
                recommended_relay_url: _,
                marker: _,
            } => {
                if event.kind == EventKind::EventDeletion {
                    // Find the other event
                    let maybe_other_event = GLOBALS.feed_events.lock().await.get(id).cloned();
                    if let Some(deleted_feed_event) = maybe_other_event {
                        match &deleted_feed_event.event {
                            None => {
                                // Can't verify the author. Take no action
                            }
                            Some(deleted_event) => {
                                if deleted_event.pubkey != event.pubkey {
                                    // Invalid delete event, author does not match
                                    warn!("Somebody tried to delete someone elses event");
                                    GLOBALS.feed_events.lock().await.remove(id);
                                    return Ok(());
                                } else {
                                    update_feed_event(*id, |er| {
                                        er.deleted_reason = Some(event.content.clone());
                                    })
                                    .await;
                                }
                            }
                        }
                    } else {
                        // FIXME - currently we don't apply this deletion event
                        // if we don't have the event it refers to because we cannot
                        // check that the authors match.
                        // but if we get the event it refers to later, nothing will
                        // trigger us to reapply it.
                    }
                }
            }
            Tag::Pubkey { .. } => {
                // Maybe we can generally handle these?
                // Maybe it is too specific to certain event types.
                // For now we process these under specific event types.
            }
            Tag::Hashtag(s) => {
                update_feed_event(event.id, |er| {
                    er.hashtags.push(s.to_string());
                })
                .await;
            }
            Tag::Reference(r) => {
                update_feed_event(event.id, |er| {
                    er.urls.push(r.to_string());
                })
                .await;
            }
            Tag::Geohash(_) => {} // not implemented
            Tag::Subject(s) => {
                update_feed_event(event.id, |er| {
                    er.subject = Some(s.to_string());
                })
                .await;
            }
            Tag::Nonce { .. } => {} // not implemented
            Tag::Other { tag, data } => {
                if tag == "client" && !data.is_empty() {
                    update_feed_event(event.id, |er| {
                        er.client = Some(data[0].to_string());
                    })
                    .await;
                }
            }
            Tag::Empty => {} // nothing to do
        }
    }

    if event.kind == EventKind::Reaction {
        for tag in event.tags.iter() {
            if let Tag::Event {
                id,
                recommended_relay_url: _,
                marker: _,
            } = tag
            {
                // last 'e' is the id reacted to
                if event.content.starts_with('+') {
                    update_feed_event(id.to_owned(), |er| {
                        er.reactions.upvotes += 1;
                    })
                    .await;
                } else if event.content.starts_with('-') {
                    update_feed_event(id.to_owned(), |er| {
                        er.reactions.downvotes += 1;
                    })
                    .await;
                } else if event.content.is_empty() {
                    // consider it an upvote
                    update_feed_event(id.to_owned(), |er| {
                        er.reactions.upvotes += 1;
                    })
                    .await;
                } else {
                    // consider it an emoji
                    update_feed_event(id.to_owned(), |er| {
                        // FIXME: If it exists, increment it
                        er.reactions
                            .emojis
                            .push((event.content.chars().next().unwrap(), 1))
                    })
                    .await;
                }
            }
        }
    }

    Ok(())
}

async fn insert_event(event: &Event) {
    let mut feed_events = GLOBALS.feed_events.lock().await;

    feed_events
        .entry(event.id)
        .and_modify(|feed_event| {
            // If the event already exists, update it's base data.
            // (sometimes it is created to add feed data, but doesn't have base data yet)
            feed_event.feed_related = event.kind == EventKind::TextNote;
            if feed_event.last_reply_at.is_none() {
                feed_event.last_reply_at = Some(event.created_at.0)
            }
            if feed_event.event.is_none() {
                feed_event.event = Some(event.to_owned());
            }
        })
        .or_insert_with(|| event.into());
}

async fn update_feed_event<F>(id: Id, mut f: F)
where
    F: FnMut(&mut FeedEvent),
{
    let mut feed_events = GLOBALS.feed_events.lock().await;
    let feed_event = feed_events.entry(id).or_insert_with(|| FeedEvent::new(id));
    f(feed_event);
}

pub async fn update_person_from_event_metadata(
    pubkey: PublicKey,
    created_at: Unixtime,
    metadata: Metadata,
) {
    let mut people = GLOBALS.people.lock().await;
    let person = people
        .entry(pubkey)
        .or_insert_with(|| DbPerson::new(pubkey.into()));

    // Do not update the metadata if ours is newer
    if let Some(metadata_at) = person.metadata_at {
        if created_at.0 <= metadata_at {
            // Old metadata. Ignore it
            return;
        }
    }

    // Update the metadata
    person.name = metadata.name;
    person.about = metadata.about;
    person.picture = metadata.picture;
    if person.dns_id != metadata.nip05 {
        person.dns_id = metadata.nip05;
        person.dns_id_valid = 0; // changed, so reset to invalid
        person.dns_id_last_checked = None; // we haven't checked this one yet
    }
    person.metadata_at = Some(created_at.0);
}

#[allow(dead_code)]
async fn save_person(pubkey: PublicKey) -> Result<(), Error> {
    let mut people = GLOBALS.people.lock().await;
    let person = people
        .entry(pubkey)
        .or_insert_with(|| DbPerson::new(pubkey.into()));

    DbPerson::update(person.clone()).await?;
    Ok(())
}

pub async fn followed_pubkeys() -> Vec<PublicKeyHex> {
    let people = GLOBALS.people.lock().await;
    people
        .iter()
        .map(|(_, p)| p)
        .filter(|p| p.followed == 1)
        .map(|p| p.pubkey.clone())
        .collect()
}

#[allow(dead_code)]
pub async fn follow_key_and_relay(pubkey: String, relay: String) -> Result<DbPerson, String> {
    let pubkeyhex = PublicKeyHex(pubkey.clone());

    // Create or update them
    let person = match DbPerson::fetch_one(pubkeyhex.clone())
        .await
        .map_err(|e| format!("{}", e))?
    {
        Some(mut person) => {
            person.followed = 1;
            DbPerson::update(person.clone())
                .await
                .map_err(|e| format!("{}", e))?;
            person
        }
        None => {
            let mut person = DbPerson::new(pubkeyhex.clone());
            person.followed = 1;
            DbPerson::insert(person.clone())
                .await
                .map_err(|e| format!("{}", e))?;
            person
        }
    };

    // Insert (or ignore) this relay
    DbRelay::insert(DbRelay::new(relay.clone()))
        .await
        .map_err(|e| format!("{}", e))?;

    // Insert (or ignore) this person's relay
    DbPersonRelay::insert(DbPersonRelay {
        person: pubkey,
        relay,
        ..Default::default()
    })
    .await
    .map_err(|e| format!("{}", e))?;

    // Tell the overlord to update the  minion to watch for their events
    // possibly starting a new minion if necessary.
    // FIXME TODO

    // Reply to javascript with the person which will be set in the store
    Ok(person)
}