//! Notifications, watching, subscriptions and the search index (hub spec
//! §10, §11).

use super::{now_ms, Pool};
use sqlx::FromRow;

#[derive(Clone, Debug, FromRow)]
pub struct Notification {
    pub id: i64,
    pub account_id: i64,
    pub at_ms: i64,
    pub kind: String,
    pub title: String,
    pub url: String,
    pub actor: String,
    pub read: bool,
    pub repo_id: Option<i64>,
    pub thread: String,
    pub reason: String,
    pub done: bool,
}

/// Why someone is told: they take part in the thread, or only watch the repository.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum Reason {
    Participating,
    Watching,
}

impl Reason {
    pub fn as_str(self) -> &'static str {
        match self {
            Reason::Participating => "participating",
            Reason::Watching => "watching",
        }
    }
}

/// The thread a notification belongs to: its page, without a fragment.
pub fn thread_of(url: &str) -> &str {
    url.split('#').next().unwrap_or(url)
}

/// A notification to record.
pub struct New<'a> {
    pub account_id: i64,
    pub repo_id: Option<i64>,
    pub reason: Reason,
    pub kind: &'a str,
    pub title: &'a str,
    pub url: &'a str,
    pub actor: &'a str,
}

pub async fn add(pool: &Pool, n: New<'_>) -> sqlx::Result<()> {
    let New { account_id, repo_id, reason, kind, title, url, actor } = n;
    // A new event brings a thread that was set aside back to the inbox.
    sqlx::query("UPDATE notifications SET done = FALSE WHERE account_id = $1 AND thread = $2 AND done = TRUE")
        .bind(account_id)
        .bind(thread_of(url))
        .execute(pool)
        .await?;
    sqlx::query("INSERT INTO notifications (account_id, at_ms, kind, title, url, actor, repo_id, thread, reason) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)")
        .bind(account_id)
        .bind(now_ms())
        .bind(kind)
        .bind(title)
        .bind(url)
        .bind(actor)
        .bind(repo_id)
        .bind(thread_of(url))
        .bind(reason.as_str())
        .execute(pool)
        .await?;
    Ok(())
}

/// One inbox row: a thread, shown by its newest notification.
#[derive(Clone, Debug, FromRow)]
pub struct Thread {
    /// The newest notification's id.
    pub id: i64,
    pub at_ms: i64,
    pub kind: String,
    pub title: String,
    pub url: String,
    pub actor: String,
    pub thread: String,
    pub repo_id: Option<i64>,
    pub repo: Option<String>,
    pub count: i64,
    pub unread: i64,
    pub participating: bool,
    pub done: bool,
}

/// What the inbox shows.
#[derive(Clone, Debug, Default)]
pub struct Filter {
    pub done: bool,
    pub unread_only: bool,
    /// `participating` or `watching`.
    pub reason: Option<String>,
    /// A kind or its family (`issue` matches `issue.closed`).
    pub kind: Option<String>,
    pub repo_id: Option<i64>,
}

pub async fn threads(pool: &Pool, account_id: i64, f: &Filter, limit: i64) -> sqlx::Result<Vec<Thread>> {
    // Each thread is shown as its newest notification (row 1 by time) with
    // counts over the whole thread: window functions, so the same SQL runs on
    // SQLite and Postgres.
    let mut sql = String::from(
        "SELECT id, at_ms, kind, title, url, actor, thread, repo_id, \
         (SELECT r.owner || '/' || r.name FROM repositories r WHERE r.id = t.repo_id) AS repo, \
         count, unread, participating > 0 AS participating, done FROM (\
         SELECT n.id, n.at_ms, n.kind, n.title, n.url, n.actor, n.thread, n.repo_id, n.done, \
         ROW_NUMBER() OVER (PARTITION BY n.thread ORDER BY n.at_ms DESC, n.id DESC) AS newest, \
         COUNT(*) OVER (PARTITION BY n.thread) AS count, \
         SUM(CASE WHEN n.read THEN 0 ELSE 1 END) OVER (PARTITION BY n.thread) AS unread, \
         SUM(CASE WHEN n.reason = 'participating' THEN 1 ELSE 0 END) OVER (PARTITION BY n.thread) AS participating \
         FROM notifications n WHERE n.account_id = $1 AND n.done = $2",
    );
    // Placeholders numbered as they are added: $1 and $2 above.
    let mut next = 3;
    if f.kind.is_some() {
        sql.push_str(&format!(" AND (n.kind = ${} OR n.kind LIKE ${} || '.%')", next, next + 1));
        next += 2;
    }
    if f.repo_id.is_some() {
        sql.push_str(&format!(" AND n.repo_id = ${next}"));
        next += 1;
    }
    sql.push_str(") t WHERE newest = 1");
    if f.unread_only {
        sql.push_str(" AND unread > 0");
    }
    match f.reason.as_deref() {
        Some("participating") => sql.push_str(" AND participating > 0"),
        Some("watching") => sql.push_str(" AND participating = 0"),
        _ => {}
    }
    sql.push_str(&format!(" ORDER BY at_ms DESC LIMIT ${next}"));
    let mut q = sqlx::query_as::<_, Thread>(&sql).bind(account_id).bind(f.done);
    if let Some(k) = &f.kind {
        q = q.bind(k).bind(k);
    }
    if let Some(r) = f.repo_id {
        q = q.bind(r);
    }
    q.bind(limit).fetch_all(pool).await
}

/// Mark a thread read or unread, done or back in the inbox.
pub async fn set_thread(pool: &Pool, account_id: i64, thread: &str, read: Option<bool>, done: Option<bool>) -> sqlx::Result<()> {
    if let Some(r) = read {
        if r {
            sqlx::query("UPDATE notifications SET read = TRUE WHERE account_id = $1 AND thread = $2")
                .bind(account_id)
                .bind(thread)
                .execute(pool)
                .await?;
        } else {
            // Unread: the newest notification of the thread only.
            sqlx::query("UPDATE notifications SET read = FALSE WHERE id = (SELECT id FROM notifications WHERE account_id = $1 AND thread = $2 ORDER BY at_ms DESC, id DESC LIMIT 1)")
                .bind(account_id)
                .bind(thread)
                .execute(pool)
                .await?;
        }
    }
    if let Some(d) = done {
        let read_too = if d { ", read = TRUE" } else { "" };
        sqlx::query(&format!("UPDATE notifications SET done = $1{read_too} WHERE account_id = $2 AND thread = $3"))
            .bind(d)
            .bind(account_id)
            .bind(thread)
            .execute(pool)
            .await?;
    }
    Ok(())
}

/// The notification with this id, if it is the account's.
pub async fn get(pool: &Pool, account_id: i64, id: i64) -> sqlx::Result<Option<Notification>> {
    sqlx::query_as("SELECT * FROM notifications WHERE account_id = $1 AND id = $2").bind(account_id).bind(id).fetch_optional(pool).await
}

pub async fn inbox(pool: &Pool, account_id: i64, limit: i64) -> sqlx::Result<Vec<Notification>> {
    sqlx::query_as("SELECT * FROM notifications WHERE account_id = $1 ORDER BY read, at_ms DESC, id DESC LIMIT $2")
        .bind(account_id)
        .bind(limit)
        .fetch_all(pool)
        .await
}

pub async fn unread(pool: &Pool, account_id: i64) -> sqlx::Result<i64> {
    sqlx::query_scalar("SELECT COUNT(*) FROM notifications WHERE account_id = $1 AND read = FALSE AND done = FALSE")
        .bind(account_id)
        .fetch_one(pool)
        .await
}

pub async fn mark_read(pool: &Pool, account_id: i64, id: Option<i64>) -> sqlx::Result<()> {
    match id {
        Some(id) => {
            sqlx::query("UPDATE notifications SET read = TRUE WHERE account_id = $1 AND id = $2")
                .bind(account_id)
                .bind(id)
                .execute(pool)
                .await?
        }
        None => sqlx::query("UPDATE notifications SET read = TRUE WHERE account_id = $1").bind(account_id).execute(pool).await?,
    };
    Ok(())
}

// ---------------------------------------------------------------- watching

/// The accounts that own repository `repo_id`: its owner, or the owners of
/// the organisation that owns it. They watch it unless they mute it
/// (oxygenhub#183).
pub async fn owners_of(pool: &Pool, repo_id: i64) -> sqlx::Result<Vec<i64>> {
    let owner: Option<String> =
        sqlx::query_scalar("SELECT owner FROM repositories WHERE id = $1").bind(repo_id).fetch_optional(pool).await?;
    let Some(owner) = owner else { return Ok(Vec::new()) };
    if let Some(a) = super::accounts::account_by_name(pool, &owner).await? {
        return Ok(vec![a.id]);
    }
    match super::accounts::org_by_name(pool, &owner).await? {
        Some(o) => {
            Ok(super::accounts::org_members(pool, o.id).await?.into_iter().filter(|(_, r)| r == "owner").map(|(a, _)| a.id).collect())
        }
        None => Ok(Vec::new()),
    }
}

/// Whether `account_id` watches `repo_id`: a watch it chose, or, for an
/// owner, unless it muted it.
pub async fn watching(pool: &Pool, account_id: i64, repo_id: i64) -> sqlx::Result<bool> {
    let muted: Option<bool> = sqlx::query_scalar("SELECT muted FROM watches WHERE account_id = $1 AND repo_id = $2")
        .bind(account_id)
        .bind(repo_id)
        .fetch_optional(pool)
        .await?;
    match muted {
        Some(m) => Ok(!m),
        None => Ok(owners_of(pool, repo_id).await?.contains(&account_id)),
    }
}

/// Watch `repo_id`, or stop: for an owner, stopping mutes it.
pub async fn set_watch(pool: &Pool, account_id: i64, repo_id: i64, on: bool) -> sqlx::Result<()> {
    sqlx::query("INSERT INTO watches (account_id, repo_id, muted) VALUES ($1, $2, $3) ON CONFLICT (account_id, repo_id) DO UPDATE SET muted = excluded.muted")
        .bind(account_id)
        .bind(repo_id)
        .bind(!on)
        .execute(pool)
        .await?;
    Ok(())
}

/// Everyone watching `repo_id`: those who chose to, and its owners who
/// have not muted it.
pub async fn watchers(pool: &Pool, repo_id: i64) -> sqlx::Result<Vec<i64>> {
    let rows: Vec<(i64, bool)> =
        sqlx::query_as("SELECT account_id, muted FROM watches WHERE repo_id = $1").bind(repo_id).fetch_all(pool).await?;
    let mut out: Vec<i64> = rows.iter().filter(|(_, m)| !m).map(|(a, _)| *a).collect();
    for o in owners_of(pool, repo_id).await? {
        if !rows.iter().any(|(a, _)| *a == o) && !out.contains(&o) {
            out.push(o);
        }
    }
    Ok(out)
}

pub async fn subscribe(pool: &Pool, account_id: i64, kind: &str, target_id: i64) -> sqlx::Result<()> {
    sqlx::query("INSERT OR IGNORE INTO subscriptions (account_id, kind, target_id) VALUES ($1, $2, $3)")
        .bind(account_id)
        .bind(kind)
        .bind(target_id)
        .execute(pool)
        .await?;
    Ok(())
}

pub async fn unsubscribe(pool: &Pool, account_id: i64, kind: &str, target_id: i64) -> sqlx::Result<()> {
    sqlx::query("DELETE FROM subscriptions WHERE account_id = $1 AND kind = $2 AND target_id = $3")
        .bind(account_id)
        .bind(kind)
        .bind(target_id)
        .execute(pool)
        .await?;
    Ok(())
}

pub async fn subscribed(pool: &Pool, account_id: i64, kind: &str, target_id: i64) -> sqlx::Result<bool> {
    let n: i64 = sqlx::query_scalar("SELECT COUNT(*) FROM subscriptions WHERE account_id = $1 AND kind = $2 AND target_id = $3")
        .bind(account_id)
        .bind(kind)
        .bind(target_id)
        .fetch_one(pool)
        .await?;
    Ok(n > 0)
}

pub async fn subscribers(pool: &Pool, kind: &str, target_id: i64) -> sqlx::Result<Vec<i64>> {
    sqlx::query_scalar("SELECT account_id FROM subscriptions WHERE kind = $1 AND target_id = $2")
        .bind(kind)
        .bind(target_id)
        .fetch_all(pool)
        .await
}

// ------------------------------------------------------------------ search

#[derive(Clone, Debug, FromRow)]
pub struct Hit {
    pub kind: String,
    pub repo_id: i64,
    pub target_id: i64,
    pub number: i64,
    pub title: String,
    pub snippet: String,
}

/// Replace the indexed text of one thread (title plus body plus comments).
pub async fn index(pool: &Pool, kind: &str, repo_id: i64, target_id: i64, number: i64, title: &str, body: &str) -> sqlx::Result<()> {
    sqlx::query("DELETE FROM search WHERE kind = $1 AND target_id = $2").bind(kind).bind(target_id).execute(pool).await?;
    sqlx::query("INSERT INTO search (kind, repo_id, target_id, number, title, body) VALUES ($1, $2, $3, $4, $5, $6)")
        .bind(kind)
        .bind(repo_id)
        .bind(target_id)
        .bind(number)
        .bind(title)
        .bind(body)
        .execute(pool)
        .await?;
    Ok(())
}

/// Full-text hits, best first. The query is quoted so punctuation cannot
/// reach the FTS5 parser.
#[cfg(not(feature = "postgres"))]
pub async fn search(pool: &Pool, query: &str, repo_id: Option<i64>, limit: i64) -> sqlx::Result<Vec<Hit>> {
    let terms: Vec<String> = query.split_whitespace().map(|t| format!("\"{}\"", t.replace('"', ""))).collect();
    if terms.is_empty() {
        return Ok(vec![]);
    }
    let q = terms.join(" ");
    let sql = "SELECT kind, repo_id, target_id, number, title, snippet(search, 5, '<mark>', '</mark>', '…', 12) AS snippet FROM search WHERE search MATCH $1 AND ($2 IS NULL OR repo_id = $3) ORDER BY rank LIMIT $4";
    sqlx::query_as(sql).bind(q).bind(repo_id).bind(repo_id).bind(limit).fetch_all(pool).await
}

/// Full-text hits, best first, as SQLite's: every word must appear
/// (stemmed, as FTS5's porter tokenizer does), titles weigh more, and the
/// snippet is from the body with the words marked.
#[cfg(feature = "postgres")]
pub async fn search(pool: &Pool, query: &str, repo_id: Option<i64>, limit: i64) -> sqlx::Result<Vec<Hit>> {
    if query.split_whitespace().next().is_none() {
        return Ok(vec![]);
    }
    let sql = "SELECT kind, repo_id, target_id, number, title, \
               ts_headline('english', body, q, 'StartSel=\"<mark>\", StopSel=\"</mark>\", MaxWords=12, MinWords=4') AS snippet \
               FROM search, plainto_tsquery('english', $1) q WHERE doc @@ q AND ($2 IS NULL OR repo_id = $3) \
               ORDER BY ts_rank(doc, q) DESC LIMIT $4";
    sqlx::query_as(sql).bind(query).bind(repo_id).bind(repo_id).bind(limit).fetch_all(pool).await
}