use crate::Error;
use ruma::{
    events::{
        room::member::RoomMemberEventContent, AnyEphemeralRoomEvent, AnyInitialStateEvent,
        AnyRoomEvent, AnyStateEvent, AnyStrippedStateEvent, AnySyncRoomEvent, AnySyncStateEvent,
        EventType, StateEvent,
    },
    serde::{CanonicalJsonObject, CanonicalJsonValue, Raw},
    state_res, EventId, MilliSecondsSinceUnixEpoch, RoomId, RoomVersionId, UInt, UserId,
};
use serde::{Deserialize, Serialize};
use serde_json::{
    json,
    value::{to_raw_value, RawValue as RawJsonValue},
};
use std::{cmp::Ordering, collections::BTreeMap, convert::TryFrom};
use tracing::warn;

/// Content hashes of a PDU.
#[derive(Clone, Debug, Deserialize, Serialize)]
pub struct EventHash {
    /// The SHA-256 hash.
    pub sha256: String,
}

#[derive(Clone, Deserialize, Serialize, Debug)]
pub struct PduEvent {
    pub event_id: EventId,
    pub room_id: RoomId,
    pub sender: UserId,
    pub origin_server_ts: UInt,
    #[serde(rename = "type")]
    pub kind: EventType,
    pub content: Box<RawJsonValue>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub state_key: Option<String>,
    pub prev_events: Vec<EventId>,
    pub depth: UInt,
    pub auth_events: Vec<EventId>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub redacts: Option<EventId>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub unsigned: Option<Box<RawJsonValue>>,
    pub hashes: EventHash,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub signatures: Option<Box<RawJsonValue>>, // BTreeMap<Box<ServerName>, BTreeMap<ServerSigningKeyId, String>>
}

impl PduEvent {
    #[tracing::instrument(skip(self))]
    pub fn redact(&mut self, reason: &PduEvent) -> crate::Result<()> {
        self.unsigned = None;

        let allowed: &[&str] = match self.kind {
            EventType::RoomMember => &["membership"],
            EventType::RoomCreate => &["creator"],
            EventType::RoomJoinRules => &["join_rule"],
            EventType::RoomPowerLevels => &[
                "ban",
                "events",
                "events_default",
                "kick",
                "redact",
                "state_default",
                "users",
                "users_default",
            ],
            EventType::RoomHistoryVisibility => &["history_visibility"],
            _ => &[],
        };

        let mut old_content: BTreeMap<String, serde_json::Value> =
            serde_json::from_str(self.content.get())
                .map_err(|_| Error::bad_database("PDU in db has invalid content."))?;

        let mut new_content = serde_json::Map::new();

        for key in allowed {
            if let Some(value) = old_content.remove(*key) {
                new_content.insert((*key).to_owned(), value);
            }
        }

        self.unsigned = Some(to_raw_value(&json!({
            "redacted_because": serde_json::to_value(reason).expect("to_value(PduEvent) always works")
        })).expect("to string always works"));

        self.content = to_raw_value(&new_content).expect("to string always works");

        Ok(())
    }

    pub fn remove_transaction_id(&mut self) -> crate::Result<()> {
        if let Some(unsigned) = &self.unsigned {
            let mut unsigned: BTreeMap<String, Box<RawJsonValue>> =
                serde_json::from_str(unsigned.get())
                    .map_err(|_| Error::bad_database("Invalid unsigned in pdu event"))?;
            unsigned.remove("transaction_id");
            self.unsigned = Some(to_raw_value(&unsigned).expect("unsigned is valid"));
        }

        Ok(())
    }

    #[tracing::instrument(skip(self))]
    pub fn to_sync_room_event(&self) -> Raw<AnySyncRoomEvent> {
        let mut json = json!({
            "content": self.content,
            "type": self.kind,
            "event_id": self.event_id,
            "sender": self.sender,
            "origin_server_ts": self.origin_server_ts,
            "unsigned": self.unsigned,
        });

        if let Some(state_key) = &self.state_key {
            json["state_key"] = json!(state_key);
        }
        if let Some(redacts) = &self.redacts {
            json["redacts"] = json!(redacts);
        }

        serde_json::from_value(json).expect("Raw::from_value always works")
    }

    /// This only works for events that are also AnyRoomEvents.
    #[tracing::instrument(skip(self))]
    pub fn to_any_event(&self) -> Raw<AnyEphemeralRoomEvent> {
        let mut json = json!({
            "content": self.content,
            "type": self.kind,
            "event_id": self.event_id,
            "sender": self.sender,
            "origin_server_ts": self.origin_server_ts,
            "unsigned": self.unsigned,
            "room_id": self.room_id,
        });

        if let Some(state_key) = &self.state_key {
            json["state_key"] = json!(state_key);
        }
        if let Some(redacts) = &self.redacts {
            json["redacts"] = json!(redacts);
        }

        serde_json::from_value(json).expect("Raw::from_value always works")
    }

    #[tracing::instrument(skip(self))]
    pub fn to_room_event(&self) -> Raw<AnyRoomEvent> {
        let mut json = json!({
            "content": self.content,
            "type": self.kind,
            "event_id": self.event_id,
            "sender": self.sender,
            "origin_server_ts": self.origin_server_ts,
            "unsigned": self.unsigned,
            "room_id": self.room_id,
        });

        if let Some(state_key) = &self.state_key {
            json["state_key"] = json!(state_key);
        }
        if let Some(redacts) = &self.redacts {
            json["redacts"] = json!(redacts);
        }

        serde_json::from_value(json).expect("Raw::from_value always works")
    }

    #[tracing::instrument(skip(self))]
    pub fn to_state_event(&self) -> Raw<AnyStateEvent> {
        let json = json!({
            "content": self.content,
            "type": self.kind,
            "event_id": self.event_id,
            "sender": self.sender,
            "origin_server_ts": self.origin_server_ts,
            "unsigned": self.unsigned,
            "room_id": self.room_id,
            "state_key": self.state_key,
        });

        serde_json::from_value(json).expect("Raw::from_value always works")
    }

    #[tracing::instrument(skip(self))]
    pub fn to_sync_state_event(&self) -> Raw<AnySyncStateEvent> {
        let json = json!({
            "content": self.content,
            "type": self.kind,
            "event_id": self.event_id,
            "sender": self.sender,
            "origin_server_ts": self.origin_server_ts,
            "unsigned": self.unsigned,
            "state_key": self.state_key,
        });

        serde_json::from_value(json).expect("Raw::from_value always works")
    }

    #[tracing::instrument(skip(self))]
    pub fn to_stripped_state_event(&self) -> Raw<AnyStrippedStateEvent> {
        let json = json!({
            "content": self.content,
            "type": self.kind,
            "sender": self.sender,
            "state_key": self.state_key,
        });

        serde_json::from_value(json).expect("Raw::from_value always works")
    }

    #[tracing::instrument(skip(self))]
    pub fn to_member_event(&self) -> Raw<StateEvent<RoomMemberEventContent>> {
        let json = json!({
            "content": self.content,
            "type": self.kind,
            "event_id": self.event_id,
            "sender": self.sender,
            "origin_server_ts": self.origin_server_ts,
            "redacts": self.redacts,
            "unsigned": self.unsigned,
            "room_id": self.room_id,
            "state_key": self.state_key,
        });

        serde_json::from_value(json).expect("Raw::from_value always works")
    }

    /// This does not return a full `Pdu` it is only to satisfy ruma's types.
    #[tracing::instrument]
    pub fn convert_to_outgoing_federation_event(
        mut pdu_json: CanonicalJsonObject,
    ) -> Box<RawJsonValue> {
        if let Some(unsigned) = pdu_json
            .get_mut("unsigned")
            .and_then(|val| val.as_object_mut())
        {
            unsigned.remove("transaction_id");
        }

        pdu_json.remove("event_id");

        // TODO: another option would be to convert it to a canonical string to validate size
        // and return a Result<Raw<...>>
        // serde_json::from_str::<Raw<_>>(
        //     ruma::serde::to_canonical_json_string(pdu_json).expect("CanonicalJson is valid serde_json::Value"),
        // )
        // .expect("Raw::from_value always works")

        to_raw_value(&pdu_json).expect("CanonicalJson is valid serde_json::Value")
    }

    pub fn from_id_val(
        event_id: &EventId,
        mut json: CanonicalJsonObject,
    ) -> Result<Self, serde_json::Error> {
        json.insert(
            "event_id".to_owned(),
            CanonicalJsonValue::String(event_id.as_str().to_owned()),
        );

        serde_json::from_value(serde_json::to_value(json).expect("valid JSON"))
    }
}

impl state_res::Event for PduEvent {
    fn event_id(&self) -> &EventId {
        &self.event_id
    }

    fn room_id(&self) -> &RoomId {
        &self.room_id
    }

    fn sender(&self) -> &UserId {
        &self.sender
    }

    fn event_type(&self) -> &EventType {
        &self.kind
    }

    fn content(&self) -> &RawJsonValue {
        &self.content
    }

    fn origin_server_ts(&self) -> MilliSecondsSinceUnixEpoch {
        MilliSecondsSinceUnixEpoch(self.origin_server_ts)
    }

    fn state_key(&self) -> Option<&str> {
        self.state_key.as_deref()
    }

    fn prev_events(&self) -> Box<dyn DoubleEndedIterator<Item = &EventId> + '_> {
        Box::new(self.prev_events.iter())
    }

    fn auth_events(&self) -> Box<dyn DoubleEndedIterator<Item = &EventId> + '_> {
        Box::new(self.auth_events.iter())
    }

    fn redacts(&self) -> Option<&EventId> {
        self.redacts.as_ref()
    }
}

// These impl's allow us to dedup state snapshots when resolving state
// for incoming events (federation/send/{txn}).
impl Eq for PduEvent {}
impl PartialEq for PduEvent {
    fn eq(&self, other: &Self) -> bool {
        self.event_id == other.event_id
    }
}
impl PartialOrd for PduEvent {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        self.event_id.partial_cmp(&other.event_id)
    }
}
impl Ord for PduEvent {
    fn cmp(&self, other: &Self) -> Ordering {
        self.event_id.cmp(&other.event_id)
    }
}

/// Generates a correct eventId for the incoming pdu.
///
/// Returns a tuple of the new `EventId` and the PDU as a `BTreeMap<String, CanonicalJsonValue>`.
pub(crate) fn gen_event_id_canonical_json(
    pdu: &RawJsonValue,
) -> crate::Result<(EventId, CanonicalJsonObject)> {
    let value = serde_json::from_str(pdu.get()).map_err(|e| {
        warn!("Error parsing incoming event {:?}: {:?}", pdu, e);
        Error::BadServerResponse("Invalid PDU in server response")
    })?;

    let event_id = EventId::try_from(&*format!(
        "${}",
        // Anything higher than version3 behaves the same
        ruma::signatures::reference_hash(&value, &RoomVersionId::Version6)
            .expect("ruma can calculate reference hashes")
    ))
    .expect("ruma's reference hashes are valid event ids");

    Ok((event_id, value))
}

/// Build the start of a PDU in order to add it to the `Database`.
#[derive(Debug, Deserialize)]
pub struct PduBuilder {
    #[serde(rename = "type")]
    pub event_type: EventType,
    pub content: Box<RawJsonValue>,
    pub unsigned: Option<BTreeMap<String, serde_json::Value>>,
    pub state_key: Option<String>,
    pub redacts: Option<EventId>,
}

/// Direct conversion prevents loss of the empty `state_key` that ruma requires.
impl From<AnyInitialStateEvent> for PduBuilder {
    fn from(event: AnyInitialStateEvent) -> Self {
        Self {
            event_type: EventType::from(event.event_type()),
            content: to_raw_value(&event.content())
                .expect("AnyStateEventContent came from JSON and can thus turn back into JSON."),
            unsigned: None,
            state_key: Some(event.state_key().to_owned()),
            redacts: None,
        }
    }
}