// This file is part of Moonfire NVR, a security camera digital video recorder.
// Copyright (C) 2018 Scott Lamb <slamb@slamb.org>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// In addition, as a special exception, the copyright holders give
// permission to link the code of portions of this program with the
// OpenSSL library under certain conditions as described in each
// individual source file, and distribute linked combinations including
// the two.
//
// You must obey the GNU General Public License in all respects for all
// of the code used other than OpenSSL. If you modify file(s) with this
// exception, you may extend this exception to your version of the
// file(s), but you are not obligated to do so. If you do not wish to do
// so, delete this exception statement from your version. If you delete
// this exception statement from all source files in the program, then
// also delete it here.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

//! Raw database access: SQLite statements which do not touch any cached state.

use db::{self, CompositeId, FromSqlUuid};
use failure::{Error, ResultExt};
use fnv::FnvHashSet;
use recording;
use rusqlite;
use std::ops::Range;
use uuid::Uuid;

// Note: the magic number "27000000" below is recording::MAX_RECORDING_DURATION.
const LIST_RECORDINGS_BY_TIME_SQL: &'static str = r#"
    select
        recording.composite_id,
        recording.run_offset,
        recording.flags,
        recording.start_time_90k,
        recording.duration_90k,
        recording.sample_file_bytes,
        recording.video_samples,
        recording.video_sync_samples,
        recording.video_sample_entry_id,
        recording.open_id
    from
        recording
    where
        stream_id = :stream_id and
        recording.start_time_90k > :start_time_90k - 27000000 and
        recording.start_time_90k < :end_time_90k and
        recording.start_time_90k + recording.duration_90k > :start_time_90k
    order by
        recording.start_time_90k
"#;

const LIST_RECORDINGS_BY_ID_SQL: &'static str = r#"
    select
        recording.composite_id,
        recording.run_offset,
        recording.flags,
        recording.start_time_90k,
        recording.duration_90k,
        recording.sample_file_bytes,
        recording.video_samples,
        recording.video_sync_samples,
        recording.video_sample_entry_id,
        recording.open_id
    from
        recording
    where
        :start <= composite_id and
        composite_id < :end
    order by
        recording.composite_id
"#;

const STREAM_MIN_START_SQL: &'static str = r#"
    select
      start_time_90k
    from
      recording
    where
      stream_id = :stream_id
    order by start_time_90k limit 1
"#;

const STREAM_MAX_START_SQL: &'static str = r#"
    select
      start_time_90k,
      duration_90k
    from
      recording
    where
      stream_id = :stream_id
    order by start_time_90k desc;
"#;

const LIST_OLDEST_RECORDINGS_SQL: &'static str = r#"
    select
      composite_id,
      start_time_90k,
      duration_90k,
      sample_file_bytes
    from
      recording
    where
      :start <= composite_id and
      composite_id < :end
    order by
      composite_id
"#;

/// Lists the specified recordings in ascending order by start time, passing them to a supplied
/// function. Given that the function is called with the database lock held, it should be quick.
pub(crate) fn list_recordings_by_time(
    conn: &rusqlite::Connection, stream_id: i32, desired_time: Range<recording::Time>,
    f: &mut FnMut(db::ListRecordingsRow) -> Result<(), Error>) -> Result<(), Error> {
    let mut stmt = conn.prepare_cached(LIST_RECORDINGS_BY_TIME_SQL)?;
    let rows = stmt.query_named(&[
        (":stream_id", &stream_id),
        (":start_time_90k", &desired_time.start.0),
        (":end_time_90k", &desired_time.end.0)])?;
    list_recordings_inner(rows, f)
}

/// Lists the specified recordings in ascending order by id.
pub(crate) fn list_recordings_by_id(
    conn: &rusqlite::Connection, stream_id: i32, desired_ids: Range<i32>,
    f: &mut FnMut(db::ListRecordingsRow) -> Result<(), Error>) -> Result<(), Error> {
    let mut stmt = conn.prepare_cached(LIST_RECORDINGS_BY_ID_SQL)?;
    let rows = stmt.query_named(&[
        (":start", &CompositeId::new(stream_id, desired_ids.start).0),
        (":end", &CompositeId::new(stream_id, desired_ids.end).0),
    ])?;
    list_recordings_inner(rows, f)
}

fn list_recordings_inner(mut rows: rusqlite::Rows,
                         f: &mut FnMut(db::ListRecordingsRow) -> Result<(), Error>)
                         -> Result<(), Error> {
    while let Some(row) = rows.next() {
        let row = row?;
        f(db::ListRecordingsRow {
            id: CompositeId(row.get_checked(0)?),
            run_offset: row.get_checked(1)?,
            flags: row.get_checked(2)?,
            start: recording::Time(row.get_checked(3)?),
            duration_90k: row.get_checked(4)?,
            sample_file_bytes: row.get_checked(5)?,
            video_samples: row.get_checked(6)?,
            video_sync_samples: row.get_checked(7)?,
            video_sample_entry_id: row.get_checked(8)?,
            open_id: row.get_checked(9)?,
        })?;
    }
    Ok(())
}

pub(crate) fn get_db_uuid(conn: &rusqlite::Connection) -> Result<Uuid, Error> {
    conn.query_row("select uuid from meta", &[], |row| -> Result<Uuid, Error> {
        let uuid: FromSqlUuid = row.get_checked(0)?;
        Ok(uuid.0)
    })?
}

/// Inserts the specified recording (for from `try_flush` only).
pub(crate) fn insert_recording(tx: &rusqlite::Transaction, o: &db::Open, id: CompositeId,
                    r: &db::RecordingToInsert) -> Result<(), Error> {
    let mut stmt = tx.prepare_cached(r#"
        insert into recording (composite_id, stream_id, open_id, run_offset, flags,
                               sample_file_bytes, start_time_90k, duration_90k,
                               video_samples, video_sync_samples, video_sample_entry_id)
                       values (:composite_id, :stream_id, :open_id, :run_offset, :flags,
                               :sample_file_bytes, :start_time_90k, :duration_90k,
                               :video_samples, :video_sync_samples,
                               :video_sample_entry_id)
    "#).with_context(|e| format!("can't prepare recording insert: {}", e))?;
    stmt.execute_named(&[
        (":composite_id", &id.0),
        (":stream_id", &(id.stream() as i64)),
        (":open_id", &o.id),
        (":run_offset", &r.run_offset),
        (":flags", &r.flags),
        (":sample_file_bytes", &r.sample_file_bytes),
        (":start_time_90k", &r.start.0),
        (":duration_90k", &r.duration_90k),
        (":video_samples", &r.video_samples),
        (":video_sync_samples", &r.video_sync_samples),
        (":video_sample_entry_id", &r.video_sample_entry_id),
    ]).with_context(|e| format!("unable to insert recording for {:#?}: {}", r, e))?;

    let mut stmt = tx.prepare_cached(r#"
        insert into recording_integrity (composite_id,  local_time_delta_90k,  sample_file_sha1)
                                 values (:composite_id, :local_time_delta_90k, :sample_file_sha1)
    "#).with_context(|e| format!("can't prepare recording_integrity insert: {}", e))?;
    let sha1 = &r.sample_file_sha1[..];
    let delta = match r.run_offset {
        0 => None,
        _ => Some(r.local_time_delta.0),
    };
    stmt.execute_named(&[
        (":composite_id", &id.0),
        (":local_time_delta_90k", &delta),
        (":sample_file_sha1", &sha1),
    ]).with_context(|e| format!("unable to insert recording_integrity for {:#?}: {}", r, e))?;

    let mut stmt = tx.prepare_cached(r#"
        insert into recording_playback (composite_id,  video_index)
                                values (:composite_id, :video_index)
    "#).with_context(|e| format!("can't prepare recording_playback insert: {}", e))?;
    stmt.execute_named(&[
        (":composite_id", &id.0),
        (":video_index", &r.video_index),
    ]).with_context(|e| format!("unable to insert recording_playback for {:#?}: {}", r, e))?;

    Ok(())
}

/// Tranfers the given recording range from the `recording` and `recording_playback` tables to the
/// `garbage` table. `sample_file_dir_id` is assumed to be correct.
///
/// Returns the number of recordings which were deleted.
pub(crate) fn delete_recordings(tx: &rusqlite::Transaction, sample_file_dir_id: i32,
                                ids: Range<CompositeId>)
                                -> Result<usize, Error> {
    let mut insert = tx.prepare_cached(r#"
        insert into garbage (sample_file_dir_id, composite_id)
        select
          :sample_file_dir_id,
          composite_id
        from
          recording
        where
          :start <= composite_id and
          composite_id < :end
    "#)?;
    let mut del1 = tx.prepare_cached(r#"
        delete from recording_playback
        where
          :start <= composite_id and
          composite_id < :end
    "#)?;
    let mut del2 = tx.prepare_cached(r#"
        delete from recording_integrity
        where
          :start <= composite_id and
          composite_id < :end
    "#)?;
    let mut del3 = tx.prepare_cached(r#"
        delete from recording
        where
          :start <= composite_id and
          composite_id < :end
    "#)?;
    let n = insert.execute_named(&[
        (":sample_file_dir_id", &sample_file_dir_id),
        (":start", &ids.start.0),
        (":end", &ids.end.0),
    ])?;
    let p: &[(&str, &rusqlite::types::ToSql)] = &[
        (":start", &ids.start.0),
        (":end", &ids.end.0),
    ];
    let n1 = del1.execute_named(p)?;
    if n1 != n {
        bail!("inserted {} garbage rows but deleted {} recording_playback rows!", n, n1);
    }
    let n2 = del2.execute_named(p)?;
    if n2 > n {  // fewer is okay; recording_integrity is optional.
        bail!("inserted {} garbage rows but deleted {} recording_integrity rows!", n, n2);
    }
    let n3 = del3.execute_named(p)?;
    if n3 != n {
        bail!("deleted {} recording rows but {} recording_playback rows!", n3, n);
    }
    Ok(n)
}

/// Marks the given sample files as deleted. This shouldn't be called until the files have
/// been `unlink()`ed and the parent directory `fsync()`ed.
pub(crate) fn mark_sample_files_deleted(tx: &rusqlite::Transaction, ids: &[CompositeId])
                                        -> Result<(), Error> {
    if ids.is_empty() { return Ok(()); }
    let mut stmt = tx.prepare_cached("delete from garbage where composite_id = ?")?;
    for &id in ids {
        let changes = stmt.execute(&[&id.0])?;
        if changes != 1 {
            // panic rather than return error. Errors get retried indefinitely, but there's no
            // recovery from this condition.
            //
            // Tempting to just consider logging error and moving on, but this represents a logic
            // flaw, so complain loudly. The freshly deleted file might still be referenced in the
            // recording table.
            panic!("no garbage row for {}", id);
        }
    }
    Ok(())
}

/// Gets the time range of recordings for the given stream.
pub(crate) fn get_range(conn: &rusqlite::Connection, stream_id: i32)
                        -> Result<Option<Range<recording::Time>>, Error> {
    // The minimum is straightforward, taking advantage of the start_time_90k index.
    let mut stmt = conn.prepare_cached(STREAM_MIN_START_SQL)?;
    let mut rows = stmt.query_named(&[(":stream_id", &stream_id)])?;
    let min_start = match rows.next() {
        Some(row) => recording::Time(row?.get_checked(0)?),
        None => return Ok(None),
    };

    // There was a minimum, so there should be a maximum too. Calculating it is less
    // straightforward because recordings could overlap. All recordings starting in the
    // last MAX_RECORDING_DURATION must be examined in order to take advantage of the
    // start_time_90k index.
    let mut stmt = conn.prepare_cached(STREAM_MAX_START_SQL)?;
    let mut rows = stmt.query_named(&[(":stream_id", &stream_id)])?;
    let mut maxes_opt = None;
    while let Some(row) = rows.next() {
        let row = row?;
        let row_start = recording::Time(row.get_checked(0)?);
        let row_duration: i64 = row.get_checked(1)?;
        let row_end = recording::Time(row_start.0 + row_duration);
        let maxes = match maxes_opt {
            None => row_start .. row_end,
            Some(Range{start: s, end: e}) => s .. ::std::cmp::max(e, row_end),
        };
        if row_start.0 <= maxes.start.0 - recording::MAX_RECORDING_DURATION {
            break;
        }
        maxes_opt = Some(maxes);
    }
    let max_end = match maxes_opt {
        Some(Range{start: _, end: e}) => e,
        None => bail!("missing max for stream {} which had min {}", stream_id, min_start),
    };
    Ok(Some(min_start .. max_end))
}

/// Lists all garbage ids for the given sample file directory.
pub(crate) fn list_garbage(conn: &rusqlite::Connection, dir_id: i32)
                           -> Result<FnvHashSet<CompositeId>, Error> {
    let mut garbage = FnvHashSet::default();
    let mut stmt = conn.prepare_cached(
        "select composite_id from garbage where sample_file_dir_id = ?")?;
    let mut rows = stmt.query(&[&dir_id])?;
    while let Some(row) = rows.next() {
        let row = row?;
        garbage.insert(CompositeId(row.get_checked(0)?));
    }
    Ok(garbage)
}

/// Lists the oldest recordings for a stream, starting with the given id.
/// `f` should return true as long as further rows are desired.
pub(crate) fn list_oldest_recordings(conn: &rusqlite::Connection, start: CompositeId,
                                     f: &mut FnMut(db::ListOldestRecordingsRow) -> bool)
    -> Result<(), Error> {
    let mut stmt = conn.prepare_cached(LIST_OLDEST_RECORDINGS_SQL)?;
    let mut rows = stmt.query_named(&[
        (":start", &start.0),
        (":end", &CompositeId::new(start.stream() + 1, 0).0),
    ])?;
    while let Some(row) = rows.next() {
        let row = row?;
        let should_continue = f(db::ListOldestRecordingsRow {
            id: CompositeId(row.get_checked(0)?),
            start: recording::Time(row.get_checked(1)?),
            duration: row.get_checked(2)?,
            sample_file_bytes: row.get_checked(3)?,
        });
        if !should_continue {
            break;
        }
    }
    Ok(())
}