//! WebSocket-lag for sanntid via PG LISTEN/NOTIFY.
//!
//! Portvokteren lytter på `node_changed`, `edge_changed`, `access_changed`
//! og `mixer_channel_changed` kanaler i PostgreSQL og videresender relevante
//! endringer via WebSocket til tilkoblede klienter, filtrert på tilgangsmatrisen.
//!
//! Events berikes med full raddata fra PG slik at klienten kan oppdatere stores direkte.
//! Ref: docs/retninger/datalaget.md

use std::sync::Arc;

use axum::{
    extract::{
        ws::{Message, WebSocket},
        State, WebSocketUpgrade,
    },
    response::Response,
};
use serde::{Deserialize, Serialize};
use sqlx::postgres::PgListener;
use sqlx::PgPool;
use tokio::sync::broadcast;
use uuid::Uuid;


// ---------------------------------------------------------------------------
// Typer for NOTIFY-payloads (minimale, fra PG triggers)
// ---------------------------------------------------------------------------

#[derive(Debug, Clone, Deserialize)]
struct NodeNotify {
    op: String,
    id: Uuid,
    kind: String,
}

#[derive(Debug, Clone, Deserialize)]
struct EdgeNotify {
    op: String,
    id: Uuid,
    source_id: Uuid,
    target_id: Uuid,
    edge_type: String,
}

#[derive(Debug, Clone, Deserialize)]
struct AccessNotify {
    op: String,
    subject_id: Uuid,
    object_id: Uuid,
    access: Option<String>,
}

#[derive(Debug, Clone, Deserialize)]
struct MixerChannelNotify {
    op: String,
    room_id: String,
    target_user_id: String,
}

// ---------------------------------------------------------------------------
// Berikede WsEvent-typer (sendt til klienter, med full raddata)
// ---------------------------------------------------------------------------

/// WebSocket-melding sendt til klienter. Berikes med full raddata for
/// INSERT/UPDATE slik at frontend kan oppdatere stores direkte.
#[derive(Debug, Clone, Serialize)]
#[serde(tag = "type")]
pub enum WsEvent {
    #[serde(rename = "node_changed")]
    NodeChanged {
        op: String,
        id: String,
        kind: String,
        /// Full node-data for INSERT/UPDATE, None for DELETE.
        #[serde(skip_serializing_if = "Option::is_none")]
        node: Option<serde_json::Value>,
    },
    #[serde(rename = "edge_changed")]
    EdgeChanged {
        op: String,
        id: String,
        source_id: String,
        target_id: String,
        edge_type: String,
        /// Full edge-data for INSERT/UPDATE, None for DELETE.
        #[serde(skip_serializing_if = "Option::is_none")]
        edge: Option<serde_json::Value>,
    },
    #[serde(rename = "access_changed")]
    AccessChanged {
        op: String,
        subject_id: String,
        object_id: String,
        #[serde(skip_serializing_if = "Option::is_none")]
        access: Option<String>,
        /// Full access-rad for INSERT/UPDATE.
        #[serde(skip_serializing_if = "Option::is_none")]
        row: Option<serde_json::Value>,
    },
    #[serde(rename = "mixer_channel_changed")]
    MixerChannelChanged {
        op: String,
        room_id: String,
        target_user_id: String,
        /// Full mixer_channel-data for INSERT/UPDATE, None for DELETE.
        #[serde(skip_serializing_if = "Option::is_none")]
        channel: Option<serde_json::Value>,
    },
    /// Initiell snapshot av alle noder, edges, access og mixer_channels.
    #[serde(rename = "initial_sync")]
    InitialSync {
        nodes: Vec<serde_json::Value>,
        edges: Vec<serde_json::Value>,
        access: Vec<serde_json::Value>,
        mixer_channels: Vec<serde_json::Value>,
    },
}

/// Intern enum for broadcast — bærer UUID-er for filtrering.
/// Konverteres til WsEvent ved serialisering.
#[derive(Debug, Clone)]
enum BroadcastEvent {
    NodeChanged {
        op: String,
        id: Uuid,
        kind: String,
        node: Option<serde_json::Value>,
    },
    EdgeChanged {
        op: String,
        id: Uuid,
        source_id: Uuid,
        target_id: Uuid,
        edge_type: String,
        edge: Option<serde_json::Value>,
    },
    AccessChanged {
        op: String,
        subject_id: Uuid,
        object_id: Uuid,
        access: Option<String>,
        row: Option<serde_json::Value>,
    },
    MixerChannelChanged {
        op: String,
        room_id: String,
        target_user_id: String,
        channel: Option<serde_json::Value>,
    },
}

impl BroadcastEvent {
    fn to_ws_event(&self) -> WsEvent {
        match self {
            BroadcastEvent::NodeChanged { op, id, kind, node } => WsEvent::NodeChanged {
                op: op.clone(),
                id: id.to_string(),
                kind: kind.clone(),
                node: node.clone(),
            },
            BroadcastEvent::EdgeChanged { op, id, source_id, target_id, edge_type, edge } => WsEvent::EdgeChanged {
                op: op.clone(),
                id: id.to_string(),
                source_id: source_id.to_string(),
                target_id: target_id.to_string(),
                edge_type: edge_type.clone(),
                edge: edge.clone(),
            },
            BroadcastEvent::AccessChanged { op, subject_id, object_id, access, row } => WsEvent::AccessChanged {
                op: op.clone(),
                subject_id: subject_id.to_string(),
                object_id: object_id.to_string(),
                access: access.clone(),
                row: row.clone(),
            },
            BroadcastEvent::MixerChannelChanged { op, room_id, target_user_id, channel } => WsEvent::MixerChannelChanged {
                op: op.clone(),
                room_id: room_id.clone(),
                target_user_id: target_user_id.clone(),
                channel: channel.clone(),
            },
        }
    }
}

// ---------------------------------------------------------------------------
// Broadcast-kanal
// ---------------------------------------------------------------------------

#[derive(Clone)]
pub struct WsBroadcast {
    tx: broadcast::Sender<BroadcastEvent>,
}

impl WsBroadcast {
    pub fn new() -> Self {
        let (tx, _) = broadcast::channel(4096);
        Self { tx }
    }
}

// ---------------------------------------------------------------------------
// PG LISTEN + berikelse
// ---------------------------------------------------------------------------

pub fn start_pg_listener(db: PgPool, ws: WsBroadcast) {
    tokio::spawn(async move {
        loop {
            if let Err(e) = pg_listen_loop(&db, &ws).await {
                tracing::error!("PG LISTEN feilet: {e}, prøver igjen om 2s");
                tokio::time::sleep(std::time::Duration::from_secs(2)).await;
            }
        }
    });
}

async fn pg_listen_loop(db: &PgPool, ws: &WsBroadcast) -> Result<(), sqlx::Error> {
    let mut listener = PgListener::connect_with(db).await?;
    listener
        .listen_all(["node_changed", "edge_changed", "access_changed", "mixer_channel_changed"])
        .await?;

    tracing::info!("PG LISTEN startet — lytter på node_changed, edge_changed, access_changed, mixer_channel_changed");

    loop {
        let notification = listener.recv().await?;
        let channel = notification.channel();
        let payload = notification.payload();

        let event = match channel {
            "node_changed" => {
                let n: NodeNotify = match serde_json::from_str(payload) {
                    Ok(v) => v,
                    Err(e) => { tracing::warn!("Ugyldig node_changed-payload: {e}"); continue; }
                };
                let node = if n.op != "DELETE" {
                    enrich_node(db, n.id).await
                } else {
                    None
                };
                BroadcastEvent::NodeChanged { op: n.op, id: n.id, kind: n.kind, node }
            }
            "edge_changed" => {
                let e: EdgeNotify = match serde_json::from_str(payload) {
                    Ok(v) => v,
                    Err(e) => { tracing::warn!("Ugyldig edge_changed-payload: {e}"); continue; }
                };
                let edge = if e.op != "DELETE" {
                    enrich_edge(db, e.id).await
                } else {
                    None
                };
                BroadcastEvent::EdgeChanged {
                    op: e.op, id: e.id, source_id: e.source_id,
                    target_id: e.target_id, edge_type: e.edge_type, edge,
                }
            }
            "access_changed" => {
                let a: AccessNotify = match serde_json::from_str(payload) {
                    Ok(v) => v,
                    Err(e) => { tracing::warn!("Ugyldig access_changed-payload: {e}"); continue; }
                };
                let row = if a.op != "DELETE" {
                    enrich_access(db, a.subject_id, a.object_id).await
                } else {
                    None
                };
                BroadcastEvent::AccessChanged {
                    op: a.op, subject_id: a.subject_id, object_id: a.object_id,
                    access: a.access, row,
                }
            }
            "mixer_channel_changed" => {
                let m: MixerChannelNotify = match serde_json::from_str(payload) {
                    Ok(v) => v,
                    Err(e) => { tracing::warn!("Ugyldig mixer_channel_changed-payload: {e}"); continue; }
                };
                let channel_data = if m.op != "DELETE" {
                    enrich_mixer_channel(db, &m.room_id, &m.target_user_id).await
                } else {
                    None
                };
                BroadcastEvent::MixerChannelChanged {
                    op: m.op, room_id: m.room_id, target_user_id: m.target_user_id,
                    channel: channel_data,
                }
            }
            _ => continue,
        };

        let _ = ws.tx.send(event);
    }
}

// ---------------------------------------------------------------------------
// Berikelse: hent full rad fra PG etter NOTIFY
// ---------------------------------------------------------------------------

async fn enrich_node(db: &PgPool, id: Uuid) -> Option<serde_json::Value> {
    let row = sqlx::query_as::<_, NodeRow>(
        "SELECT id, node_kind, title, content, visibility::text, metadata, created_at, created_by FROM nodes WHERE id = $1"
    )
    .bind(id)
    .fetch_optional(db)
    .await
    .ok()
    .flatten()?;
    Some(row.to_json())
}

async fn enrich_edge(db: &PgPool, id: Uuid) -> Option<serde_json::Value> {
    let row = sqlx::query_as::<_, EdgeRow>(
        "SELECT id, source_id, target_id, edge_type, metadata, system, created_at, created_by FROM edges WHERE id = $1"
    )
    .bind(id)
    .fetch_optional(db)
    .await
    .ok()
    .flatten()?;
    Some(row.to_json())
}

async fn enrich_access(db: &PgPool, subject_id: Uuid, object_id: Uuid) -> Option<serde_json::Value> {
    let row = sqlx::query_as::<_, AccessRow>(
        "SELECT subject_id, object_id, access::text, via_edge FROM node_access WHERE subject_id = $1 AND object_id = $2"
    )
    .bind(subject_id)
    .bind(object_id)
    .fetch_optional(db)
    .await
    .ok()
    .flatten()?;
    Some(row.to_json())
}

async fn enrich_mixer_channel(db: &PgPool, room_id: &str, target_user_id: &str) -> Option<serde_json::Value> {
    let row = sqlx::query_as::<_, MixerChannelRow>(
        "SELECT room_id, target_user_id, gain, is_muted, active_effects, role, updated_by, updated_at FROM mixer_channels WHERE room_id = $1 AND target_user_id = $2"
    )
    .bind(room_id)
    .bind(target_user_id)
    .fetch_optional(db)
    .await
    .ok()
    .flatten()?;
    Some(row.to_json())
}

// ---------------------------------------------------------------------------
// WebSocket-endepunkt
// ---------------------------------------------------------------------------

#[derive(Deserialize)]
pub struct WsQuery {
    token: String,
}

pub async fn ws_handler(
    ws: WebSocketUpgrade,
    axum::extract::Query(query): axum::extract::Query<WsQuery>,
    State(state): State<crate::AppState>,
) -> Result<Response, (axum::http::StatusCode, String)> {
    let user = validate_ws_token(&query.token, &state)
        .await
        .map_err(|e| (axum::http::StatusCode::UNAUTHORIZED, e))?;

    tracing::info!(node_id = %user.node_id, "WebSocket-tilkobling fra bruker");

    Ok(ws.on_upgrade(move |socket| handle_socket(socket, user, state)))
}

async fn validate_ws_token(
    token: &str,
    state: &crate::AppState,
) -> Result<WsUser, String> {
    use jsonwebtoken::{decode, decode_header, Algorithm, Validation};

    let header = decode_header(token)
        .map_err(|e| format!("Ugyldig token-header: {e}"))?;

    let decoding_key = state.jwks.decoding_key(header.kid.as_deref())
        .map_err(|e| format!("JWKS-nøkkel ikke funnet: {e}"))?;

    let mut validation = Validation::new(Algorithm::RS256);
    validation.set_issuer(&[&state.jwks.issuer]);
    validation.set_audience(&[&state.jwks.audience]);

    let token_data = decode::<WsClaims>(token, &decoding_key, &validation)
        .map_err(|e| format!("JWT-validering feilet: {e}"))?;

    let authentik_sub = &token_data.claims.sub;

    let node_id = sqlx::query_scalar::<_, Uuid>(
        "SELECT node_id FROM auth_identities WHERE authentik_sub = $1",
    )
    .bind(authentik_sub)
    .fetch_optional(&state.db)
    .await
    .map_err(|e| format!("DB-feil: {e}"))?
    .ok_or_else(|| format!("Ukjent brukeridentitet: {authentik_sub}"))?;

    Ok(WsUser { node_id })
}

#[derive(Deserialize)]
struct WsClaims {
    sub: String,
}

#[derive(Debug, Clone)]
struct WsUser {
    node_id: Uuid,
}

async fn handle_socket(mut socket: WebSocket, user: WsUser, state: crate::AppState) {
    let user_id = user.node_id;

    let visible_nodes = match load_visible_nodes(&state.db, user_id).await {
        Ok(v) => Arc::new(tokio::sync::RwLock::new(v)),
        Err(e) => {
            tracing::error!("Kunne ikke laste tilgangsmatrise: {e}");
            let _ = socket.send(Message::Close(None)).await;
            return;
        }
    };

    // Send initiell snapshot
    match build_initial_sync(&state.db, user_id).await {
        Ok(sync) => {
            let json = serde_json::to_string(&sync).unwrap_or_default();
            if socket.send(Message::Text(json.into())).await.is_err() {
                return;
            }
        }
        Err(e) => {
            tracing::error!("Feil ved bygging av initial_sync: {e}");
        }
    }

    let mut rx = state.ws_broadcast.tx.subscribe();

    loop {
        tokio::select! {
            result = rx.recv() => {
                match result {
                    Ok(event) => {
                        let should_send = should_send_to_user(&event, user_id, &visible_nodes).await;
                        if should_send {
                            // Oppdater tilgangsmatrise ved access-endringer
                            if let BroadcastEvent::AccessChanged { ref op, subject_id, object_id, .. } = event {
                                if subject_id == user_id {
                                    let mut vn = visible_nodes.write().await;
                                    if op == "DELETE" {
                                        vn.remove(&object_id);
                                    } else {
                                        vn.insert(object_id);
                                    }
                                }
                            }

                            let ws_event = event.to_ws_event();
                            let json = match serde_json::to_string(&ws_event) {
                                Ok(j) => j,
                                Err(_) => continue,
                            };
                            if socket.send(Message::Text(json.into())).await.is_err() {
                                break;
                            }
                        }
                    }
                    Err(broadcast::error::RecvError::Lagged(n)) => {
                        tracing::warn!(
                            node_id = %user_id,
                            skipped = n,
                            "WebSocket-klient sakket etter, mistet {n} meldinger — sender resync"
                        );
                        // Send full resync ved lag
                        if let Ok(sync) = build_initial_sync(&state.db, user_id).await {
                            let json = serde_json::to_string(&sync).unwrap_or_default();
                            if socket.send(Message::Text(json.into())).await.is_err() {
                                break;
                            }
                        }
                    }
                    Err(broadcast::error::RecvError::Closed) => break,
                }
            }
            msg = socket.recv() => {
                match msg {
                    Some(Ok(Message::Close(_))) | None => break,
                    Some(Ok(Message::Ping(data))) => {
                        if socket.send(Message::Pong(data)).await.is_err() {
                            break;
                        }
                    }
                    Some(Err(_)) => break,
                    _ => {}
                }
            }
        }
    }

    tracing::info!(node_id = %user_id, "WebSocket-tilkobling lukket");
}

// ---------------------------------------------------------------------------
// Tilgangskontroll
// ---------------------------------------------------------------------------

async fn should_send_to_user(
    event: &BroadcastEvent,
    user_id: Uuid,
    visible_nodes: &tokio::sync::RwLock<std::collections::HashSet<Uuid>>,
) -> bool {
    match event {
        BroadcastEvent::NodeChanged { id, .. } => {
            let vn = visible_nodes.read().await;
            vn.contains(id)
        }
        BroadcastEvent::EdgeChanged { source_id, target_id, .. } => {
            let vn = visible_nodes.read().await;
            vn.contains(source_id) || vn.contains(target_id)
        }
        BroadcastEvent::AccessChanged { subject_id, .. } => *subject_id == user_id,
        // Mixer-kanaler sendes til alle (de er per-rom, ingen node-tilgangskontroll)
        BroadcastEvent::MixerChannelChanged { .. } => true,
    }
}

async fn load_visible_nodes(
    db: &PgPool,
    user_id: Uuid,
) -> Result<std::collections::HashSet<Uuid>, sqlx::Error> {
    let rows = sqlx::query_scalar::<_, Uuid>(
        r#"
        SELECT id FROM nodes WHERE created_by = $1
        UNION
        SELECT object_id FROM node_access WHERE subject_id = $1
        UNION
        SELECT id FROM nodes WHERE visibility IN ('readable', 'open')
        "#,
    )
    .bind(user_id)
    .fetch_all(db)
    .await?;

    Ok(rows.into_iter().collect())
}

async fn build_initial_sync(
    db: &PgPool,
    user_id: Uuid,
) -> Result<WsEvent, sqlx::Error> {
    let nodes = sqlx::query_as::<_, NodeRow>(
        r#"
        SELECT n.id, n.node_kind, n.title, n.content, n.visibility::text,
               n.metadata, n.created_at, n.created_by
        FROM nodes n
        WHERE n.created_by = $1
           OR n.id IN (SELECT object_id FROM node_access WHERE subject_id = $1)
           OR n.visibility IN ('readable', 'open')
        "#,
    )
    .bind(user_id)
    .fetch_all(db)
    .await?;

    let node_ids: Vec<Uuid> = nodes.iter().map(|n| n.id).collect();

    let edges = sqlx::query_as::<_, EdgeRow>(
        r#"
        SELECT e.id, e.source_id, e.target_id, e.edge_type,
               e.metadata, e.system, e.created_at, e.created_by
        FROM edges e
        WHERE e.source_id = ANY($1) OR e.target_id = ANY($1)
        "#,
    )
    .bind(&node_ids)
    .fetch_all(db)
    .await?;

    let access = sqlx::query_as::<_, AccessRow>(
        r#"
        SELECT subject_id, object_id, access::text, via_edge
        FROM node_access
        WHERE subject_id = $1
        "#,
    )
    .bind(user_id)
    .fetch_all(db)
    .await?;

    // Mixer-kanaler: alle (ingen tilgangskontroll på rom-nivå foreløpig)
    let mixer_channels = sqlx::query_as::<_, MixerChannelRow>(
        "SELECT room_id, target_user_id, gain, is_muted, active_effects, role, updated_by, updated_at FROM mixer_channels"
    )
    .fetch_all(db)
    .await?;

    Ok(WsEvent::InitialSync {
        nodes: nodes.into_iter().map(|n| n.to_json()).collect(),
        edges: edges.into_iter().map(|e| e.to_json()).collect(),
        access: access.into_iter().map(|a| a.to_json()).collect(),
        mixer_channels: mixer_channels.into_iter().map(|m| m.to_json()).collect(),
    })
}

// ---------------------------------------------------------------------------
// DB-rader
// ---------------------------------------------------------------------------

#[derive(sqlx::FromRow)]
struct NodeRow {
    id: Uuid,
    node_kind: String,
    title: Option<String>,
    content: Option<String>,
    visibility: String,
    metadata: serde_json::Value,
    created_at: chrono::DateTime<chrono::Utc>,
    created_by: Option<Uuid>,
}

impl NodeRow {
    fn to_json(&self) -> serde_json::Value {
        serde_json::json!({
            "id": self.id.to_string(),
            "nodeKind": self.node_kind,
            "title": self.title.as_deref().unwrap_or(""),
            "content": self.content.as_deref().unwrap_or(""),
            "visibility": self.visibility,
            "metadata": self.metadata.to_string(),
            "createdAt": self.created_at.timestamp_micros(),
            "createdBy": self.created_by.map(|u| u.to_string()).unwrap_or_default(),
        })
    }
}

#[derive(sqlx::FromRow)]
struct EdgeRow {
    id: Uuid,
    source_id: Uuid,
    target_id: Uuid,
    edge_type: String,
    metadata: serde_json::Value,
    system: bool,
    created_at: chrono::DateTime<chrono::Utc>,
    created_by: Option<Uuid>,
}

impl EdgeRow {
    fn to_json(&self) -> serde_json::Value {
        serde_json::json!({
            "id": self.id.to_string(),
            "sourceId": self.source_id.to_string(),
            "targetId": self.target_id.to_string(),
            "edgeType": self.edge_type,
            "metadata": self.metadata.to_string(),
            "system": self.system,
            "createdAt": self.created_at.timestamp_micros(),
            "createdBy": self.created_by.map(|u| u.to_string()).unwrap_or_default(),
        })
    }
}

#[derive(sqlx::FromRow)]
struct AccessRow {
    subject_id: Uuid,
    object_id: Uuid,
    access: String,
    via_edge: Option<Uuid>,
}

impl AccessRow {
    fn to_json(&self) -> serde_json::Value {
        serde_json::json!({
            "id": format!("{}:{}", self.subject_id, self.object_id),
            "subjectId": self.subject_id.to_string(),
            "objectId": self.object_id.to_string(),
            "access": self.access,
            "viaEdge": self.via_edge.map(|u| u.to_string()).unwrap_or_default(),
        })
    }
}

#[derive(sqlx::FromRow)]
struct MixerChannelRow {
    room_id: String,
    target_user_id: String,
    gain: f64,
    is_muted: bool,
    active_effects: String,
    role: String,
    updated_by: String,
    updated_at: chrono::DateTime<chrono::Utc>,
}

impl MixerChannelRow {
    fn to_json(&self) -> serde_json::Value {
        serde_json::json!({
            "id": format!("{}:{}", self.room_id, self.target_user_id),
            "roomId": self.room_id,
            "targetUserId": self.target_user_id,
            "gain": self.gain,
            "isMuted": self.is_muted,
            "activeEffects": self.active_effects,
            "role": self.role,
            "updatedBy": self.updated_by,
            "updatedAt": self.updated_at.timestamp_micros(),
        })
    }
}