//! 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 = 0 WHERE account_id = ? AND thread = ? AND done = 1")
        .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 (?, ?, ?, ?, ?, ?, ?, ?, ?)")
        .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>> {
    // SQLite takes bare columns from the row holding MAX(at_ms): the newest.
    let mut sql = String::from(
        "SELECT n.id, MAX(n.at_ms) AS at_ms, n.kind, n.title, n.url, n.actor, n.thread, n.repo_id, \
         (SELECT r.owner || '/' || r.name FROM repositories r WHERE r.id = n.repo_id) AS repo, \
         COUNT(*) AS count, SUM(n.read = 0) AS unread, SUM(n.reason = 'participating') > 0 AS participating, n.done \
         FROM notifications n WHERE n.account_id = ? AND n.done = ?",
    );
    if f.kind.is_some() {
        sql.push_str(" AND (n.kind = ? OR n.kind LIKE ? || '.%')");
    }
    if f.repo_id.is_some() {
        sql.push_str(" AND n.repo_id = ?");
    }
    sql.push_str(" GROUP BY n.thread HAVING 1");
    if f.unread_only {
        sql.push_str(" AND SUM(n.read = 0) > 0");
    }
    match f.reason.as_deref() {
        Some("participating") => sql.push_str(" AND SUM(n.reason = 'participating') > 0"),
        Some("watching") => sql.push_str(" AND SUM(n.reason = 'participating') = 0"),
        _ => {}
    }
    sql.push_str(" ORDER BY at_ms DESC LIMIT ?");
    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 = 1 WHERE account_id = ? AND thread = ?")
                .bind(account_id)
                .bind(thread)
                .execute(pool)
                .await?;
        } else {
            // Unread: the newest notification of the thread only.
            sqlx::query("UPDATE notifications SET read = 0 WHERE id = (SELECT id FROM notifications WHERE account_id = ? AND thread = ? 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 = 1" } else { "" };
        sqlx::query(&format!("UPDATE notifications SET done = ?{read_too} WHERE account_id = ? AND thread = ?"))
            .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 = ? AND id = ?").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 = ? ORDER BY read, at_ms DESC, id DESC LIMIT ?")
        .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 = ? AND read = 0 AND done = 0")
        .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 = 1 WHERE account_id = ? AND id = ?").bind(account_id).bind(id).execute(pool).await?
        }
        None => sqlx::query("UPDATE notifications SET read = 1 WHERE account_id = ?").bind(account_id).execute(pool).await?,
    };
    Ok(())
}

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

pub async fn watching(pool: &Pool, account_id: i64, repo_id: i64) -> sqlx::Result<bool> {
    let n: i64 = sqlx::query_scalar("SELECT COUNT(*) FROM watches WHERE account_id = ? AND repo_id = ?")
        .bind(account_id)
        .bind(repo_id)
        .fetch_one(pool)
        .await?;
    Ok(n > 0)
}

pub async fn set_watch(pool: &Pool, account_id: i64, repo_id: i64, on: bool) -> sqlx::Result<()> {
    if on {
        sqlx::query("INSERT OR IGNORE INTO watches (account_id, repo_id) VALUES (?, ?)")
            .bind(account_id)
            .bind(repo_id)
            .execute(pool)
            .await?;
    } else {
        sqlx::query("DELETE FROM watches WHERE account_id = ? AND repo_id = ?").bind(account_id).bind(repo_id).execute(pool).await?;
    }
    Ok(())
}

pub async fn watchers(pool: &Pool, repo_id: i64) -> sqlx::Result<Vec<i64>> {
    sqlx::query_scalar("SELECT account_id FROM watches WHERE repo_id = ?").bind(repo_id).fetch_all(pool).await
}

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 (?, ?, ?)")
        .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 = ? AND kind = ? AND target_id = ?")
        .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 = ? AND kind = ? AND target_id = ?")
        .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 = ? AND target_id = ?")
        .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 = ? AND target_id = ?").bind(kind).bind(target_id).execute(pool).await?;
    sqlx::query("INSERT INTO search (kind, repo_id, target_id, number, title, body) VALUES (?, ?, ?, ?, ?, ?)")
        .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.
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 ? AND (? IS NULL OR repo_id = ?) ORDER BY rank LIMIT ?";
    sqlx::query_as(sql).bind(q).bind(repo_id).bind(repo_id).bind(limit).fetch_all(pool).await
}