// Copyright 2020 TiKV Project Authors. Licensed under Apache-2.0.

// #[PerformanceCriticalPath]
use txn_types::{Key, ReqType, TimeStamp};

use crate::storage::{
    kv::WriteData,
    lock_manager::LockManager,
    mvcc::{MvccTxn, SnapshotReader},
    txn::{
        cleanup,
        commands::{
            Command, CommandExt, ReaderWithStats, ReleasedLocks, ResponsePolicy, TypedCommand,
            WriteCommand, WriteContext, WriteResult,
        },
        Result,
    },
    ProcessResult, Snapshot,
};

command! {
    /// Rollback mutations on a single key.
    ///
    /// This should be following a [`Prewrite`](Command::Prewrite) on the given key.
    Cleanup:
        cmd_ty => (),
        display => "kv::command::cleanup {} @ {} | {:?}", (key, start_ts, ctx),
        content => {
            key: Key,
            /// The transaction timestamp.
            start_ts: TimeStamp,
            /// The approximate current ts when cleanup request is invoked, which is used to check the
            /// lock's TTL. 0 means do not check TTL.
            current_ts: TimeStamp,
        }
}

impl CommandExt for Cleanup {
    ctx!();
    tag!(cleanup);
    request_type!(KvCleanup);
    ts!(start_ts);
    write_bytes!(key);
    gen_lock!(key);
}

impl<S: Snapshot, L: LockManager> WriteCommand<S, L> for Cleanup {
    fn process_write(self, snapshot: S, context: WriteContext<'_, L>) -> Result<WriteResult> {
        // It is not allowed for commit to overwrite a protected rollback. So we update
        // max_ts to prevent this case from happening.
        context.concurrency_manager.update_max_ts(self.start_ts);

        let mut txn = MvccTxn::new(self.start_ts, context.concurrency_manager);
        let mut reader = ReaderWithStats::new(
            SnapshotReader::new_with_ctx(self.start_ts, snapshot, &self.ctx),
            context.statistics,
        );

        let mut released_locks = ReleasedLocks::new();
        // The rollback must be protected, see more on
        // [issue #7364](https://github.com/tikv/tikv/issues/7364)
        released_locks.push(cleanup(
            &mut txn,
            &mut reader,
            self.key,
            self.current_ts,
            true,
        )?);

        let mut write_data = WriteData::from_modifies(txn.into_modifies());
        write_data.set_req_type(ReqType::Rollback);
        write_data.set_allowed_on_disk_almost_full();
        Ok(WriteResult {
            ctx: self.ctx,
            to_be_write: write_data,
            rows: 1,
            pr: ProcessResult::Res,
            lock_info: vec![],
            released_locks,
            lock_guards: vec![],
            response_policy: ResponsePolicy::OnApplied,
        })
    }
}