bacnet-objects 0.12.0

//! Shared resident storage and identity projection for BACnet log objects.

use std::collections::VecDeque;

use bacnet_encoding::constructed::{
    encode_event_log_record, encode_log_multiple_record, encode_log_record,
};
use bacnet_types::bitstring::LogStatus;
use bacnet_types::constructed::{
    BACnetEventLogRecord, BACnetLogMultipleRecord, BACnetLogRecord, EventLogDatum, LogData,
    LogDatum,
};
use bacnet_types::enums::{ErrorClass, ErrorCode, PropertyIdentifier as P};
use bacnet_types::error::Error;
use bacnet_types::primitives::{Date, Time};
use bytes::BytesMut;

use crate::property_metadata::{
    PropertyConformance::RequiredRead, PropertyMetadata, PropertyWriteCapability::ReadOnly,
};

// Shared conformance rows only. LOG_BUFFER is a present, read-only BACnetLIST
// that ReadProperty refuses; ReadRange pages it through `LogBufferRecords`.
pub(crate) const BUFFER_SIZE_METADATA: PropertyMetadata =
    PropertyMetadata::new(P::BUFFER_SIZE, RequiredRead, None, ReadOnly);
pub(crate) const LOG_BUFFER_METADATA: PropertyMetadata =
    PropertyMetadata::new(P::LOG_BUFFER, RequiredRead, None, ReadOnly);
pub(crate) const TOTAL_RECORD_COUNT_METADATA: PropertyMetadata =
    PropertyMetadata::new(P::TOTAL_RECORD_COUNT, RequiredRead, None, ReadOnly);

/// The answer a log object gives a ReadProperty of its Log_Buffer.
///
/// Clauses 12.25.14, 12.27.13, 12.30.19 and 12.64.10 open a log buffer to
/// ReadRange (and, for an Audit Log, AuditLogQuery) only, so a property read
/// names the property as present but not readable this way
/// (Clause 15.5.1.3.1).
pub(crate) fn log_buffer_read_denied() -> Error {
    Error::Protocol {
        class: ErrorClass::PROPERTY.to_raw() as u32,
        code: ErrorCode::READ_ACCESS_DENIED.to_raw() as u32,
    }
}

/// A log object's Log_Buffer as ReadRange pages it: the resident records,
/// oldest first, each framed on demand as its Clause 21 record production.
///
/// The records align element for element with
/// [`crate::traits::BACnetObject::log_record_identities_internal`]. A page
/// encodes only the records it visits, so a narrow window over a full log
/// stays cheap.
pub trait LogBufferRecords {
    /// The number of resident records.
    fn record_count(&self) -> usize;

    /// Append the record at `index` (0 is the oldest) to `buf`.
    ///
    /// Encoding cannot fail: the built-in logs refuse a record that would not
    /// encode when it is added, and an implementation must keep that promise
    /// too. Panics when `index` is not below
    /// [`record_count`](Self::record_count).
    fn encode_record(&self, index: usize, buf: &mut BytesMut);
}

/// The largest encoded value, in octets, that the trend pollers log as an
/// any-value. A larger value (a long string, a big array) is logged as a
/// PROPERTY / VALUE_TOO_LONG failure instead, so that one Trend Log record
/// stays small enough for a ReadRange page on a 480-octet APDU.
pub const ANY_VALUE_MAX_OCTETS: usize = 256;

/// Stable object-owned identity for one resident log record.
///
/// Identity views returned by [`crate::traits::BACnetObject::log_record_identities_internal`]
/// are ordered oldest-to-newest and align element-for-element with the owning
/// object's resident records and `LOG_BUFFER` projection. Sequence numbers are
/// always nonzero. Event and Trend logs count in Unsigned32 and wrap from
/// `u32::MAX` to 1; Audit Log counts in Unsigned64 and wraps from `u64::MAX`.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct LogRecordIdentity {
    sequence_number: u64,
    date: Date,
    time: Time,
}

impl LogRecordIdentity {
    /// Construct an identity, rejecting zero as an invalid record sequence.
    pub fn new(sequence_number: u64, date: Date, time: Time) -> Option<Self> {
        (sequence_number != 0).then_some(Self {
            sequence_number,
            date,
            time,
        })
    }

    /// Return this record's nonzero sequence number.
    pub fn sequence_number(&self) -> u64 {
        self.sequence_number
    }

    /// Return the date owned by this record.
    pub fn date(&self) -> Date {
        self.date
    }

    /// Return the time owned by this record.
    pub fn time(&self) -> Time {
        self.time
    }
}

/// A record a [`LogRecordBuffer`] can hold: it carries its own timestamp,
/// the shared lifecycle can build the log-status record of its family, and
/// it encodes as its family's Clause 21 production.
pub(crate) trait ResidentLogRecord: Clone {
    /// The local date and time the record was acquired.
    fn timestamp(&self) -> (Date, Time);
    /// A log-status record carrying `status`.
    fn log_status(date: Date, time: Time, status: LogStatus) -> Self;
    /// Append the record's wire form to `buf`, leaving it unchanged on error.
    fn encode(&self, buf: &mut BytesMut) -> Result<(), Error>;
}

impl ResidentLogRecord for BACnetLogRecord {
    fn timestamp(&self) -> (Date, Time) {
        (self.date, self.time)
    }

    fn log_status(date: Date, time: Time, status: LogStatus) -> Self {
        Self {
            date,
            time,
            log_datum: LogDatum::LogStatus(status),
            status_flags: None,
        }
    }

    fn encode(&self, buf: &mut BytesMut) -> Result<(), Error> {
        encode_log_record(self, buf)
    }
}

impl ResidentLogRecord for BACnetEventLogRecord {
    fn timestamp(&self) -> (Date, Time) {
        (self.date, self.time)
    }

    fn log_status(date: Date, time: Time, status: LogStatus) -> Self {
        Self {
            date,
            time,
            log_datum: EventLogDatum::LogStatus(status),
        }
    }

    fn encode(&self, buf: &mut BytesMut) -> Result<(), Error> {
        encode_event_log_record(self, buf)
    }
}

impl ResidentLogRecord for BACnetLogMultipleRecord {
    fn timestamp(&self) -> (Date, Time) {
        (self.date, self.time)
    }

    fn log_status(date: Date, time: Time, status: LogStatus) -> Self {
        Self {
            date,
            time,
            log_data: LogData::LogStatus(status),
        }
    }

    fn encode(&self, buf: &mut BytesMut) -> Result<(), Error> {
        encode_log_multiple_record(self, buf)
    }
}

#[derive(Clone)]
pub(crate) struct LogRecordBuffer<R = BACnetLogRecord> {
    capacity: u32,
    records: VecDeque<R>,
    total_record_count: u32,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) enum OrdinaryAdmission {
    IgnoredDisabled,
    Inserted,
    CountOnly,
    StopBeforeFull,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) enum ForcedAdmission {
    Inserted,
    CountOnly,
}

impl<R: ResidentLogRecord> LogRecordBuffer<R> {
    pub(crate) fn new(capacity: u32) -> Self {
        Self {
            capacity,
            records: VecDeque::new(),
            total_record_count: 0,
        }
    }

    pub(crate) fn admit_ordinary(
        &mut self,
        record: R,
        enabled: bool,
        stop_when_full: bool,
    ) -> OrdinaryAdmission {
        if !enabled {
            return OrdinaryAdmission::IgnoredDisabled;
        }
        if stop_when_full && self.next_record_would_fill() {
            return OrdinaryAdmission::StopBeforeFull;
        }

        match self.insert_counted(record) {
            ForcedAdmission::Inserted => OrdinaryAdmission::Inserted,
            ForcedAdmission::CountOnly => OrdinaryAdmission::CountOnly,
        }
    }

    pub(crate) fn insert_forced(&mut self, record: R) -> ForcedAdmission {
        self.insert_counted(record)
    }

    pub(crate) fn is_full(&self) -> bool {
        self.records.len() >= self.capacity as usize
    }

    pub(crate) fn next_record_would_fill_positive_capacity(&self) -> bool {
        self.capacity > 0 && self.next_record_would_fill()
    }

    pub(crate) fn records(&self) -> &VecDeque<R> {
        &self.records
    }

    pub(crate) fn total_record_count(&self) -> u32 {
        self.total_record_count
    }

    pub(crate) fn capacity(&self) -> u32 {
        self.capacity
    }

    pub(crate) fn clear(&mut self) {
        self.records.clear();
    }

    pub(crate) fn identities(&self) -> Vec<LogRecordIdentity> {
        if self.records.is_empty() {
            return Vec::new();
        }

        debug_assert_ne!(self.total_record_count, 0);
        let mut sequence_number = self.total_record_count;
        for _ in 1..self.records.len() {
            sequence_number = previous_sequence(sequence_number);
        }

        self.records
            .iter()
            .map(|record| {
                let (date, time) = record.timestamp();
                let identity = LogRecordIdentity {
                    sequence_number: u64::from(sequence_number),
                    date,
                    time,
                };
                sequence_number = next_sequence(sequence_number);
                identity
            })
            .collect()
    }

    fn next_record_would_fill(&self) -> bool {
        self.capacity == 0 || self.records.len().saturating_add(1) >= self.capacity as usize
    }

    fn insert_counted(&mut self, record: R) -> ForcedAdmission {
        self.total_record_count = next_sequence(self.total_record_count);
        if self.capacity == 0 {
            return ForcedAdmission::CountOnly;
        }
        if self.is_full() {
            self.records.pop_front();
        }
        self.records.push_back(record);
        ForcedAdmission::Inserted
    }

    #[cfg(test)]
    pub(crate) fn set_total_record_count_for_test(&mut self, total_record_count: u32) {
        debug_assert!(self.records.is_empty());
        self.total_record_count = total_record_count;
    }
}

impl<R: ResidentLogRecord> LogBufferRecords for LogRecordBuffer<R> {
    fn record_count(&self) -> usize {
        self.records.len()
    }

    fn encode_record(&self, index: usize, buf: &mut BytesMut) {
        // `LogLifecycle::try_add_ordinary` refuses a record that would not
        // encode, the lifecycle's own status records always encode, and a
        // resident record is never changed.
        self.records[index]
            .encode(buf)
            .expect("every resident log record encodes");
    }
}

fn next_sequence(sequence_number: u32) -> u32 {
    if sequence_number == u32::MAX {
        1
    } else {
        sequence_number + 1
    }
}

fn previous_sequence(sequence_number: u32) -> u32 {
    if sequence_number == 1 {
        u32::MAX
    } else {
        sequence_number - 1
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use bacnet_types::constructed::{BACnetLogRecord, LogDatum};
    use bacnet_types::primitives::{Date, Time};

    fn record(hour: u8) -> BACnetLogRecord {
        BACnetLogRecord {
            date: Date {
                year: 126,
                month: 8,
                day: 31,
                day_of_week: 1,
            },
            time: Time {
                hour,
                minute: 0,
                second: 0,
                hundredths: 0,
            },
            log_datum: LogDatum::UnsignedValue(hour as u64),
            status_flags: None,
        }
    }

    #[test]
    fn log_buffer_assigns_one_and_wraps_max_without_zero() {
        let mut buffer = LogRecordBuffer::new(2);
        assert_eq!(buffer.total_record_count(), 0);
        assert!(LogRecordIdentity::new(0, record(0).date, record(0).time).is_none());

        assert_eq!(
            buffer.admit_ordinary(record(1), true, false),
            OrdinaryAdmission::Inserted
        );
        assert_eq!(buffer.identities()[0].sequence_number(), 1);

        buffer.clear();
        buffer.set_total_record_count_for_test(u32::MAX);
        assert_eq!(
            buffer.admit_ordinary(record(2), true, false),
            OrdinaryAdmission::Inserted
        );
        assert_eq!(buffer.total_record_count(), 1);
        assert_eq!(buffer.identities()[0].sequence_number(), 1);
    }

    #[test]
    fn log_buffer_rejections_do_not_consume_sequence() {
        let mut buffer = LogRecordBuffer::new(1);
        assert_eq!(
            buffer.admit_ordinary(record(1), false, false),
            OrdinaryAdmission::IgnoredDisabled
        );
        assert_eq!(buffer.total_record_count(), 0);

        assert_eq!(
            buffer.admit_ordinary(record(2), true, true),
            OrdinaryAdmission::StopBeforeFull
        );
        assert_eq!(buffer.total_record_count(), 0);
        assert!(buffer.identities().is_empty());
    }

    #[test]
    fn log_buffer_zero_capacity_counts_without_retaining() {
        let mut ring = LogRecordBuffer::new(0);
        assert_eq!(
            ring.admit_ordinary(record(1), true, false),
            OrdinaryAdmission::CountOnly
        );
        assert_eq!(
            ring.admit_ordinary(record(2), true, false),
            OrdinaryAdmission::CountOnly
        );
        assert!(ring.records().is_empty());
        assert_eq!(ring.total_record_count(), 2);

        let mut stop_when_full = LogRecordBuffer::new(0);
        assert_eq!(
            stop_when_full.admit_ordinary(record(1), true, true),
            OrdinaryAdmission::StopBeforeFull
        );
        assert!(stop_when_full.records().is_empty());
        assert_eq!(stop_when_full.total_record_count(), 0);
    }

    #[test]
    fn log_buffer_fifo_eviction_keeps_survivor_identity_and_alignment() {
        let mut buffer = LogRecordBuffer::new(2);
        assert_eq!(
            buffer.admit_ordinary(record(1), true, false),
            OrdinaryAdmission::Inserted
        );
        assert_eq!(
            buffer.admit_ordinary(record(2), true, false),
            OrdinaryAdmission::Inserted
        );
        let survivor = buffer.identities()[1];
        assert_eq!(
            buffer.admit_ordinary(record(3), true, false),
            OrdinaryAdmission::Inserted
        );

        let identities = buffer.identities();
        assert_eq!(
            identities,
            vec![
                survivor,
                LogRecordIdentity::new(3, record(3).date, record(3).time).unwrap()
            ]
        );
        assert_eq!(identities[0].sequence_number(), 2);
        assert_ne!(identities[0].sequence_number(), 1);
        for (record, identity) in buffer.records().iter().zip(&identities) {
            assert_eq!(identity.date(), record.date);
            assert_eq!(identity.time(), record.time);
        }
    }

    #[test]
    fn log_buffer_wrap_and_eviction_keep_modular_fifo_alignment() {
        let mut buffer = LogRecordBuffer::new(3);
        buffer.set_total_record_count_for_test(u32::MAX - 1);
        assert_eq!(
            buffer.admit_ordinary(record(1), true, false),
            OrdinaryAdmission::Inserted
        );
        assert_eq!(
            buffer.admit_ordinary(record(2), true, false),
            OrdinaryAdmission::Inserted
        );
        assert_eq!(
            buffer.admit_ordinary(record(3), true, false),
            OrdinaryAdmission::Inserted
        );
        assert_eq!(
            buffer
                .identities()
                .iter()
                .map(LogRecordIdentity::sequence_number)
                .collect::<Vec<_>>(),
            vec![u64::from(u32::MAX), 1, 2]
        );

        assert_eq!(
            buffer.admit_ordinary(record(4), true, false),
            OrdinaryAdmission::Inserted
        );
        assert_eq!(
            buffer
                .identities()
                .iter()
                .map(LogRecordIdentity::sequence_number)
                .collect::<Vec<_>>(),
            vec![1, 2, 3]
        );
        assert_eq!(
            buffer
                .records()
                .iter()
                .map(|record| record.time.hour)
                .collect::<Vec<_>>(),
            vec![2, 3, 4]
        );
    }

    #[test]
    fn log_buffer_clear_preserves_counter_and_constructor_resets_it() {
        let mut buffer = LogRecordBuffer::new(2);
        assert_eq!(
            buffer.admit_ordinary(record(1), true, false),
            OrdinaryAdmission::Inserted
        );
        assert_eq!(
            buffer.admit_ordinary(record(2), true, false),
            OrdinaryAdmission::Inserted
        );
        buffer.clear();

        assert!(buffer.records().is_empty());
        assert!(buffer.identities().is_empty());
        assert_eq!(buffer.total_record_count(), 2);
        assert_eq!(
            buffer.admit_ordinary(record(3), true, false),
            OrdinaryAdmission::Inserted
        );
        assert_eq!(buffer.identities()[0].sequence_number(), 3);
        assert_eq!(
            LogRecordBuffer::<BACnetLogRecord>::new(2).total_record_count(),
            0
        );
    }

    #[test]
    fn log_buffer_duplicate_timestamps_keep_distinct_sequences() {
        let mut buffer = LogRecordBuffer::new(2);
        let duplicate = record(4);
        assert_eq!(
            buffer.admit_ordinary(duplicate.clone(), true, false),
            OrdinaryAdmission::Inserted
        );
        assert_eq!(
            buffer.admit_ordinary(duplicate, true, false),
            OrdinaryAdmission::Inserted
        );

        let identities = buffer.identities();
        assert_eq!(identities[0].date(), identities[1].date());
        assert_eq!(identities[0].time(), identities[1].time());
        assert_eq!(identities[0].sequence_number(), 1);
        assert_eq!(identities[1].sequence_number(), 2);
    }

    #[test]
    fn log_buffer_clone_restore_preserves_payloads_and_derived_identities() {
        let mut buffer = LogRecordBuffer::new(2);
        assert_eq!(
            buffer.admit_ordinary(record(1), true, false),
            OrdinaryAdmission::Inserted
        );
        assert_eq!(
            buffer.admit_ordinary(record(2), true, false),
            OrdinaryAdmission::Inserted
        );
        let records = buffer.records().clone();
        let identities = buffer.identities();
        let total = buffer.total_record_count();

        let snapshot = buffer.clone();
        buffer.clear();
        buffer = snapshot;

        assert_eq!(buffer.records(), &records);
        assert_eq!(buffer.identities(), identities);
        assert_eq!(buffer.total_record_count(), total);
    }
}