/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

use super::schema;
use crate::api::places_api::ConnectionType;
use crate::error::*;
use interrupt_support::{SqlInterruptHandle, SqlInterruptScope};
use lazy_static::lazy_static;
use parking_lot::Mutex;
use rusqlite::{self, Connection, Transaction};
use sql_support::{
    open_database::{self, open_database_with_flags, ConnectionInitializer},
    ConnExt,
};
use std::collections::HashMap;
use std::ops::Deref;
use std::path::Path;

use std::sync::{
    atomic::{AtomicI64, Ordering},
    Arc, RwLock,
};

pub const MAX_VARIABLE_NUMBER: usize = 999;

lazy_static! {
    // Each API has a single bookmark change counter shared across all connections.
    // This hashmap indexes them by the "api id" of the API.
    pub static ref GLOBAL_BOOKMARK_CHANGE_COUNTERS: RwLock<HashMap<usize, AtomicI64>> = RwLock::new(HashMap::new());
}

pub struct PlacesInitializer {
    api_id: usize,
    conn_type: ConnectionType,
}

impl PlacesInitializer {
    #[cfg(test)]
    pub fn new_for_test() -> Self {
        Self {
            api_id: 0,
            conn_type: ConnectionType::ReadWrite,
        }
    }
}

impl ConnectionInitializer for PlacesInitializer {
    const NAME: &'static str = "places";
    const END_VERSION: u32 = schema::VERSION;

    fn init(&self, tx: &Transaction<'_>) -> open_database::Result<()> {
        Ok(schema::init(tx)?)
    }

    fn upgrade_from(&self, tx: &Transaction<'_>, version: u32) -> open_database::Result<()> {
        Ok(schema::upgrade_from(tx, version)?)
    }

    fn prepare(&self, conn: &Connection, db_empty: bool) -> open_database::Result<()> {
        // If this is an empty DB, setup incremental auto-vacuum now rather than wait for the first
        // run_maintenance_vacuum() call.  It should be much faster now with an empty DB.
        if db_empty && !matches!(self.conn_type, ConnectionType::ReadOnly) {
            conn.execute_one("PRAGMA auto_vacuum=incremental")?;
            conn.execute_one("VACUUM")?;
        }

        let initial_pragmas = "
            -- The value we use was taken from Desktop Firefox, and seems necessary to
            -- help ensure good performance on autocomplete-style queries.
            -- Modern default value is 4096, but as reported in
            -- https://bugzilla.mozilla.org/show_bug.cgi?id=1782283, desktop places saw
            -- a nice improvement with this value.
            PRAGMA page_size = 32768;

            -- Disable calling mlock/munlock for every malloc/free.
            -- In practice this results in a massive speedup, especially
            -- for insert-heavy workloads.
            PRAGMA cipher_memory_security = false;

            -- `temp_store = 2` is required on Android to force the DB to keep temp
            -- files in memory, since on Android there's no tmp partition. See
            -- https://github.com/mozilla/mentat/issues/505. Ideally we'd only
            -- do this on Android, and/or allow caller to configure it.
            -- (although see also bug 1313021, where Firefox enabled it for both
            -- Android and 64bit desktop builds)
            PRAGMA temp_store = 2;

            -- 6MiB, same as the value used for `promiseLargeCacheDBConnection` in PlacesUtils,
            -- which is used to improve query performance for autocomplete-style queries (by
            -- UnifiedComplete). Note that SQLite uses a negative value for this pragma to indicate
            -- that it's in units of KiB.
            PRAGMA cache_size = -6144;

            -- We want foreign-key support.
            PRAGMA foreign_keys = ON;

            -- we unconditionally want write-ahead-logging mode
            PRAGMA journal_mode=WAL;

            -- How often to autocheckpoint (in units of pages).
            -- 2048000 (our max desired WAL size) / 32760 (page size).
            PRAGMA wal_autocheckpoint=62;

            -- How long to wait for a lock before returning SQLITE_BUSY (in ms)
            -- See `doc/sql_concurrency.md` for details.
            PRAGMA busy_timeout = 5000;
        ";
        conn.execute_batch(initial_pragmas)?;
        define_functions(conn, self.api_id)?;
        sql_support::debug_tools::define_debug_functions(conn)?;
        conn.set_prepared_statement_cache_capacity(128);
        Ok(())
    }

    fn finish(&self, conn: &Connection) -> open_database::Result<()> {
        Ok(schema::finish(conn, self.conn_type)?)
    }
}

#[derive(Debug)]
pub struct PlacesDb {
    pub db: Connection,
    conn_type: ConnectionType,
    interrupt_handle: Arc<SqlInterruptHandle>,
    api_id: usize,
    pub(super) coop_tx_lock: Arc<Mutex<()>>,
}

impl PlacesDb {
    fn with_connection(
        db: Connection,
        conn_type: ConnectionType,
        api_id: usize,
        coop_tx_lock: Arc<Mutex<()>>,
    ) -> Self {
        Self {
            interrupt_handle: Arc::new(SqlInterruptHandle::new(&db)),
            db,
            conn_type,
            // The API sets this explicitly.
            api_id,
            coop_tx_lock,
        }
    }

    pub fn open(
        path: impl AsRef<Path>,
        conn_type: ConnectionType,
        api_id: usize,
        coop_tx_lock: Arc<Mutex<()>>,
    ) -> Result<Self> {
        let initializer = PlacesInitializer { api_id, conn_type };
        let conn = open_database_with_flags(path, conn_type.rusqlite_flags(), &initializer)?;
        Ok(Self::with_connection(conn, conn_type, api_id, coop_tx_lock))
    }

    #[cfg(test)]
    // Useful for some tests (although most tests should use helper functions
    // in api::places_api::test)
    pub fn open_in_memory(conn_type: ConnectionType) -> Result<Self> {
        let initializer = PlacesInitializer {
            api_id: 0,
            conn_type,
        };
        let conn = open_database::open_memory_database_with_flags(
            conn_type.rusqlite_flags(),
            &initializer,
        )?;
        Ok(Self::with_connection(
            conn,
            conn_type,
            0,
            Arc::new(Mutex::new(())),
        ))
    }

    pub fn new_interrupt_handle(&self) -> Arc<SqlInterruptHandle> {
        Arc::clone(&self.interrupt_handle)
    }

    #[inline]
    pub fn begin_interrupt_scope(&self) -> Result<SqlInterruptScope> {
        Ok(self.interrupt_handle.begin_interrupt_scope()?)
    }

    #[inline]
    pub fn conn_type(&self) -> ConnectionType {
        self.conn_type
    }

    /// Returns an object that can tell you whether any changes have been made
    /// to bookmarks since this was called.
    /// While this conceptually should live on the PlacesApi, the things that
    /// need this typically only have a PlacesDb, so we expose it here.
    pub fn global_bookmark_change_tracker(&self) -> GlobalChangeCounterTracker {
        GlobalChangeCounterTracker::new(self.api_id)
    }

    #[inline]
    pub fn api_id(&self) -> usize {
        self.api_id
    }
}

impl Drop for PlacesDb {
    fn drop(&mut self) {
        // In line with both the recommendations from SQLite and the behavior of places in
        // Database.cpp, we run `PRAGMA optimize` before closing the connection.
        if let ConnectionType::ReadOnly = self.conn_type() {
            // A reader connection can't execute an optimize
            return;
        }
        let res = self.db.execute_batch("PRAGMA optimize(0x02);");
        if let Err(e) = res {
            warn!("Failed to execute pragma optimize (DB locked?): {}", e);
        }
    }
}

impl ConnExt for PlacesDb {
    #[inline]
    fn conn(&self) -> &Connection {
        &self.db
    }
}

impl Deref for PlacesDb {
    type Target = Connection;
    #[inline]
    fn deref(&self) -> &Connection {
        &self.db
    }
}

/// PlacesDB that's behind a Mutex so it can be shared between threads
pub struct SharedPlacesDb {
    db: Mutex<PlacesDb>,
    interrupt_handle: Arc<SqlInterruptHandle>,
}

impl SharedPlacesDb {
    pub fn new(db: PlacesDb) -> Self {
        Self {
            interrupt_handle: db.new_interrupt_handle(),
            db: Mutex::new(db),
        }
    }

    pub fn begin_interrupt_scope(&self) -> Result<SqlInterruptScope> {
        Ok(self.interrupt_handle.begin_interrupt_scope()?)
    }
}

// Deref to a Mutex<PlacesDb>, which is how we will use SharedPlacesDb most of the time
impl Deref for SharedPlacesDb {
    type Target = Mutex<PlacesDb>;

    #[inline]
    fn deref(&self) -> &Mutex<PlacesDb> {
        &self.db
    }
}

// Also implement AsRef<SqlInterruptHandle> so that we can interrupt this at shutdown
impl AsRef<SqlInterruptHandle> for SharedPlacesDb {
    fn as_ref(&self) -> &SqlInterruptHandle {
        &self.interrupt_handle
    }
}

/// An object that can tell you whether a bookmark changing operation has
/// happened since the object was created.
pub struct GlobalChangeCounterTracker {
    api_id: usize,
    start_value: i64,
}

impl GlobalChangeCounterTracker {
    pub fn new(api_id: usize) -> Self {
        GlobalChangeCounterTracker {
            api_id,
            start_value: Self::cur_value(api_id),
        }
    }

    // The value is an implementation detail, so just expose what we care
    // about - ie, "has it changed?"
    pub fn changed(&self) -> bool {
        Self::cur_value(self.api_id) != self.start_value
    }

    fn cur_value(api_id: usize) -> i64 {
        let map = GLOBAL_BOOKMARK_CHANGE_COUNTERS
            .read()
            .expect("gbcc poisoned");
        match map.get(&api_id) {
            Some(counter) => counter.load(Ordering::Acquire),
            None => 0,
        }
    }
}

#[derive(Clone, Copy)]
pub enum Pragma {
    IgnoreCheckConstraints,
    ForeignKeys,
    WritableSchema,
}

impl Pragma {
    pub fn name(&self) -> &str {
        match self {
            Self::IgnoreCheckConstraints => "ignore_check_constraints",
            Self::ForeignKeys => "foreign_keys",
            Self::WritableSchema => "writable_schema",
        }
    }
}

/// A scope guard that sets a Boolean PRAGMA to a new value, and
/// restores the inverse of the value when dropped.
pub struct PragmaGuard<'a> {
    conn: &'a Connection,
    pragma: Pragma,
    old_value: bool,
}

impl<'a> PragmaGuard<'a> {
    pub fn new(conn: &'a Connection, pragma: Pragma, new_value: bool) -> rusqlite::Result<Self> {
        conn.pragma_update(
            None,
            pragma.name(),
            match new_value {
                true => "ON",
                false => "OFF",
            },
        )?;
        Ok(Self {
            conn,
            pragma,
            old_value: !new_value,
        })
    }
}

impl Drop for PragmaGuard<'_> {
    fn drop(&mut self) {
        let _ = self.conn.pragma_update(
            None,
            self.pragma.name(),
            match self.old_value {
                true => "ON",
                false => "OFF",
            },
        );
    }
}

fn define_functions(c: &Connection, api_id: usize) -> rusqlite::Result<()> {
    use rusqlite::functions::FunctionFlags;
    c.create_scalar_function(
        "get_prefix",
        1,
        FunctionFlags::SQLITE_UTF8 | FunctionFlags::SQLITE_DETERMINISTIC,
        sql_fns::get_prefix,
    )?;
    c.create_scalar_function(
        "get_host_and_port",
        1,
        FunctionFlags::SQLITE_UTF8 | FunctionFlags::SQLITE_DETERMINISTIC,
        sql_fns::get_host_and_port,
    )?;
    c.create_scalar_function(
        "strip_prefix_and_userinfo",
        1,
        FunctionFlags::SQLITE_UTF8 | FunctionFlags::SQLITE_DETERMINISTIC,
        sql_fns::strip_prefix_and_userinfo,
    )?;
    c.create_scalar_function(
        "reverse_host",
        1,
        FunctionFlags::SQLITE_UTF8 | FunctionFlags::SQLITE_DETERMINISTIC,
        sql_fns::reverse_host,
    )?;
    c.create_scalar_function(
        "autocomplete_match",
        10,
        FunctionFlags::SQLITE_UTF8 | FunctionFlags::SQLITE_DETERMINISTIC,
        sql_fns::autocomplete_match,
    )?;
    c.create_scalar_function(
        "hash",
        -1,
        FunctionFlags::SQLITE_UTF8 | FunctionFlags::SQLITE_DETERMINISTIC,
        sql_fns::hash,
    )?;
    c.create_scalar_function("now", 0, FunctionFlags::SQLITE_UTF8, sql_fns::now)?;
    c.create_scalar_function(
        "generate_guid",
        0,
        FunctionFlags::SQLITE_UTF8,
        sql_fns::generate_guid,
    )?;
    c.create_scalar_function(
        "note_bookmarks_sync_change",
        0,
        FunctionFlags::SQLITE_UTF8,
        move |ctx| -> rusqlite::Result<i64> { sql_fns::note_bookmarks_sync_change(ctx, api_id) },
    )?;
    c.create_scalar_function("throw", 1, FunctionFlags::SQLITE_UTF8, move |ctx| {
        sql_fns::throw(ctx, api_id)
    })?;
    Ok(())
}

pub(crate) mod sql_fns {
    use super::GLOBAL_BOOKMARK_CHANGE_COUNTERS;
    use crate::api::matcher::{split_after_host_and_port, split_after_prefix};
    use crate::hash;
    use crate::match_impl::{AutocompleteMatch, MatchBehavior, SearchBehavior};
    use rusqlite::types::Null;
    use rusqlite::{functions::Context, types::ValueRef, Error, Result};
    use std::sync::atomic::Ordering;
    use sync_guid::Guid as SyncGuid;
    use types::Timestamp;

    // Helpers for define_functions
    fn get_raw_str<'a>(ctx: &'a Context<'_>, fname: &'static str, idx: usize) -> Result<&'a str> {
        ctx.get_raw(idx).as_str().map_err(|e| {
            Error::UserFunctionError(format!("Bad arg {} to '{}': {}", idx, fname, e).into())
        })
    }

    fn get_raw_opt_str<'a>(
        ctx: &'a Context<'_>,
        fname: &'static str,
        idx: usize,
    ) -> Result<Option<&'a str>> {
        let raw = ctx.get_raw(idx);
        if raw == ValueRef::Null {
            return Ok(None);
        }
        Ok(Some(raw.as_str().map_err(|e| {
            Error::UserFunctionError(format!("Bad arg {} to '{}': {}", idx, fname, e).into())
        })?))
    }

    // Note: The compiler can't meaningfully inline these, but if we don't put
    // #[inline(never)] on them they get "inlined" into a temporary Box<FnMut>,
    // which doesn't have a name (and itself doesn't get inlined). Adding
    // #[inline(never)] ensures they show up in profiles.

    #[inline(never)]
    pub fn hash(ctx: &Context<'_>) -> rusqlite::Result<Option<i64>> {
        Ok(match ctx.len() {
            1 => {
                // This is a deterministic function, which means sqlite
                // does certain optimizations which means hash() may be called
                // with a null value even though the query prevents the null
                // value from actually being used. As a special case, we return
                // null when the input is NULL. We return NULL instead of zero
                // because the hash columns are NOT NULL, so attempting to
                // actually use the null should fail.
                get_raw_opt_str(ctx, "hash", 0)?.map(|value| hash::hash_url(value) as i64)
            }
            2 => {
                let value = get_raw_opt_str(ctx, "hash", 0)?;
                let mode = get_raw_str(ctx, "hash", 1)?;
                if let Some(value) = value {
                    Some(match mode {
                        "" => hash::hash_url(value),
                        "prefix_lo" => hash::hash_url_prefix(value, hash::PrefixMode::Lo),
                        "prefix_hi" => hash::hash_url_prefix(value, hash::PrefixMode::Hi),
                        arg => {
                            return Err(rusqlite::Error::UserFunctionError(format!(
                                "`hash` second argument must be either '', 'prefix_lo', or 'prefix_hi', got {:?}.",
                                arg).into()));
                        }
                    } as i64)
                } else {
                    None
                }
            }
            n => {
                return Err(rusqlite::Error::UserFunctionError(
                    format!("`hash` expects 1 or 2 arguments, got {}.", n).into(),
                ));
            }
        })
    }

    #[inline(never)]
    pub fn autocomplete_match(ctx: &Context<'_>) -> Result<bool> {
        let search_str = get_raw_str(ctx, "autocomplete_match", 0)?;
        let url_str = get_raw_str(ctx, "autocomplete_match", 1)?;
        let title_str = get_raw_opt_str(ctx, "autocomplete_match", 2)?.unwrap_or_default();
        let tags = get_raw_opt_str(ctx, "autocomplete_match", 3)?.unwrap_or_default();
        let visit_count = ctx.get::<u32>(4)?;
        let typed = ctx.get::<bool>(5)?;
        let bookmarked = ctx.get::<bool>(6)?;
        let open_page_count = ctx.get::<Option<u32>>(7)?.unwrap_or(0);
        let match_behavior = ctx.get::<MatchBehavior>(8)?;
        let search_behavior = ctx.get::<SearchBehavior>(9)?;

        let matcher = AutocompleteMatch {
            search_str,
            url_str,
            title_str,
            tags,
            visit_count,
            typed,
            bookmarked,
            open_page_count,
            match_behavior,
            search_behavior,
        };
        Ok(matcher.invoke())
    }

    #[inline(never)]
    pub fn reverse_host(ctx: &Context<'_>) -> Result<String> {
        // We reuse this memory so no need for get_raw.
        let mut host = ctx.get::<String>(0)?;
        debug_assert!(host.is_ascii(), "Hosts must be Punycoded");

        host.make_ascii_lowercase();
        let mut rev_host_bytes = host.into_bytes();
        rev_host_bytes.reverse();
        rev_host_bytes.push(b'.');

        let rev_host = String::from_utf8(rev_host_bytes).map_err(|_err| {
            rusqlite::Error::UserFunctionError("non-punycode host provided to reverse_host!".into())
        })?;
        Ok(rev_host)
    }

    #[inline(never)]
    pub fn get_prefix(ctx: &Context<'_>) -> Result<String> {
        let href = get_raw_str(ctx, "get_prefix", 0)?;
        let (prefix, _) = split_after_prefix(href);
        Ok(prefix.to_owned())
    }

    #[inline(never)]
    pub fn get_host_and_port(ctx: &Context<'_>) -> Result<String> {
        let href = get_raw_str(ctx, "get_host_and_port", 0)?;
        let (host_and_port, _) = split_after_host_and_port(href);
        Ok(host_and_port.to_owned())
    }

    #[inline(never)]
    pub fn strip_prefix_and_userinfo(ctx: &Context<'_>) -> Result<String> {
        let href = get_raw_str(ctx, "strip_prefix_and_userinfo", 0)?;
        let (host_and_port, remainder) = split_after_host_and_port(href);
        let mut res = String::with_capacity(host_and_port.len() + remainder.len() + 1);
        res += host_and_port;
        res += remainder;
        Ok(res)
    }

    #[inline(never)]
    pub fn now(_ctx: &Context<'_>) -> Result<Timestamp> {
        Ok(Timestamp::now())
    }

    #[inline(never)]
    pub fn generate_guid(_ctx: &Context<'_>) -> Result<SyncGuid> {
        Ok(SyncGuid::random())
    }

    #[inline(never)]
    pub fn throw(ctx: &Context<'_>, api_id: usize) -> Result<Null> {
        Err(rusqlite::Error::UserFunctionError(
            format!("{} (#{})", ctx.get::<String>(0)?, api_id).into(),
        ))
    }

    #[inline(never)]
    pub fn note_bookmarks_sync_change(_ctx: &Context<'_>, api_id: usize) -> Result<i64> {
        let map = GLOBAL_BOOKMARK_CHANGE_COUNTERS
            .read()
            .expect("gbcc poisoned");
        if let Some(counter) = map.get(&api_id) {
            // Because we only ever check for equality, we can use Relaxed ordering.
            return Ok(counter.fetch_add(1, Ordering::Relaxed));
        }
        // Need to add the counter to the map - drop the read lock before
        // taking the write lock.
        drop(map);
        let mut map = GLOBAL_BOOKMARK_CHANGE_COUNTERS
            .write()
            .expect("gbcc poisoned");
        let counter = map.entry(api_id).or_default();
        // Because we only ever check for equality, we can use Relaxed ordering.
        Ok(counter.fetch_add(1, Ordering::Relaxed))
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    // Sanity check that we can create a database.
    #[test]
    fn test_open() {
        PlacesDb::open_in_memory(ConnectionType::ReadWrite).expect("no memory db");
    }

    #[test]
    fn test_reverse_host() {
        let conn = PlacesDb::open_in_memory(ConnectionType::ReadWrite).expect("no memory db");
        let rev_host: String = conn
            .db
            .query_row("SELECT reverse_host('www.mozilla.org')", [], |row| {
                row.get(0)
            })
            .unwrap();
        assert_eq!(rev_host, "gro.allizom.www.");

        let rev_host: String = conn
            .db
            .query_row("SELECT reverse_host('')", [], |row| row.get(0))
            .unwrap();
        assert_eq!(rev_host, ".");
    }
}