// file: crates/ksp-job-backfill-lib/src/persistence.rs
// version: 3

/// Canonical entity disposition produced by one Backfill Store persistence attempt.
#[non_exhaustive]
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub enum BackfillEntityPersistence {
    /// The canonical RAW transaction was inserted for the first time.
    Inserted,
    /// Identical canonical RAW transaction content was already durable.
    AlreadyPresent,
    /// A durable purge tombstone prevented normal Backfill rehydration.
    SkippedPurged,
    /// `getTransaction` returned JSON `null`, so no canonical Store write was attempted.
    Missing,
    /// Store reported divergent canonical content for the same network-scoped transaction identity.
    Conflict,
}

/// Observation disposition produced by one Backfill Store persistence attempt.
#[non_exhaustive]
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub enum BackfillObservationPersistence {
    /// The deterministic acquisition observation was inserted for the first time.
    Inserted,
    /// The same deterministic acquisition observation was already durable.
    AlreadyPresent,
    /// Store intentionally recorded no observation because normal persistence skipped a purged entity or detected a conflict.
    NotRecorded,
    /// No observation existed because hydration returned `Missing` before persistence.
    NotApplicable,
}

/// Stable Backfill projection of one hydration persistence result.
///
/// The canonical transaction identity remains `(network, signature)`. Provider, endpoint and
/// transport details can affect the persisted observation but never the transaction identity.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct BackfillPersistenceOutcome {
    reference: ksp_store_lib::RawTransactionReference,
    entity: crate::BackfillEntityPersistence,
    observation: crate::BackfillObservationPersistence,
}

impl crate::BackfillPersistenceOutcome {
    /// Creates one internally classified persistence result.
    pub(crate) fn new(
        reference: ksp_store_lib::RawTransactionReference,
        entity: crate::BackfillEntityPersistence,
        observation: crate::BackfillObservationPersistence,
    ) -> Self {
        return Self { reference, entity, observation };
    }

    /// Returns the network-scoped canonical transaction identity classified by this result.
    #[must_use]
    pub fn reference(&self) -> &ksp_store_lib::RawTransactionReference {
        return &self.reference;
    }

    /// Returns the canonical transaction persistence disposition.
    #[must_use]
    pub const fn entity(&self) -> crate::BackfillEntityPersistence {
        return self.entity;
    }

    /// Returns the acquisition-observation persistence disposition.
    #[must_use]
    pub const fn observation(&self) -> crate::BackfillObservationPersistence {
        return self.observation;
    }
}

/// Persists one hydrated Backfill result through the backend-neutral Store facade.
///
/// Available acquisitions use the existing atomic transaction-plus-observation Store contract in
/// `Normal` mode. A durable purge is therefore respected and never rehydrated implicitly.
/// `Missing` performs no Store write. Stable Store content conflicts are projected explicitly as
/// [`BackfillEntityPersistence::Conflict`] rather than being silently treated as idempotent skips.
/// Other Store failures remain errors.
pub async fn persist_backfill_hydration(
    store: &ksp_store_lib::Store,
    hydration: crate::BackfillHydrationOutcome,
) -> ksp_core_lib::Result<crate::BackfillPersistenceOutcome> {
    return persist_hydration_with_port(store, hydration).await;
}

trait RawTransactionPersistencePort: std::marker::Send + std::marker::Sync {
    fn network_matches(&self, network: &ksp_store_lib::RawNetworkId) -> bool;

    fn persist_acquisition<'a>(
        &'a self,
        transaction: ksp_store_lib::RawTransaction,
        observation: ksp_store_lib::RawTransactionObservation,
        mode: ksp_store_lib::RawTransactionAcquisitionMode,
    ) -> ksp_store_lib::StoreApiFuture<'a, ksp_store_lib::Result<ksp_store_lib::RawAcquisitionWriteOutcome>>;
}

impl RawTransactionPersistencePort for ksp_store_lib::Store {
    fn network_matches(&self, network: &ksp_store_lib::RawNetworkId) -> bool {
        let snapshot = self.runtime_snapshot();
        return snapshot.network() == network;
    }

    fn persist_acquisition<'a>(
        &'a self,
        transaction: ksp_store_lib::RawTransaction,
        observation: ksp_store_lib::RawTransactionObservation,
        mode: ksp_store_lib::RawTransactionAcquisitionMode,
    ) -> ksp_store_lib::StoreApiFuture<'a, ksp_store_lib::Result<ksp_store_lib::RawAcquisitionWriteOutcome>> {
        return ksp_store_lib::RawTransactionWrite::persist_raw_transaction_acquisition(self, transaction, observation, mode);
    }
}

async fn persist_hydration_with_port<P>(port: &P, hydration: crate::BackfillHydrationOutcome) -> ksp_core_lib::Result<crate::BackfillPersistenceOutcome>
where
    P: RawTransactionPersistencePort,
{
    let reference = hydration.reference().clone();
    if !port.network_matches(reference.network()) {
        return std::result::Result::Err(persistence_error("store.network"));
    }
    return match hydration {
        crate::BackfillHydrationOutcome::Missing(_) => std::result::Result::Ok(crate::BackfillPersistenceOutcome::new(
            reference,
            crate::BackfillEntityPersistence::Missing,
            crate::BackfillObservationPersistence::NotApplicable,
        )),
        crate::BackfillHydrationOutcome::Available(acquisition) => {
            let (transaction, observation) = acquisition.into_parts();
            persist_available_with_port(port, reference, transaction, observation).await
        },
    };
}

async fn persist_available_with_port<P>(
    port: &P,
    reference: ksp_store_lib::RawTransactionReference,
    transaction: ksp_store_lib::RawTransaction,
    observation: ksp_store_lib::RawTransactionObservation,
) -> ksp_core_lib::Result<crate::BackfillPersistenceOutcome>
where
    P: RawTransactionPersistencePort,
{
    if !port.network_matches(reference.network()) {
        return std::result::Result::Err(persistence_error("store.network"));
    }
    if transaction.reference() != &reference || observation.transaction() != &reference {
        return std::result::Result::Err(persistence_error("acquisition.reference"));
    }
    let result = port.persist_acquisition(transaction, observation, ksp_store_lib::RawTransactionAcquisitionMode::Normal).await;
    return match result {
        std::result::Result::Ok(outcome) => map_store_outcome(reference, outcome),
        std::result::Result::Err(error) => {
            if error.code() == ksp_store_lib::ERROR_CODE_RAW_CONFLICT {
                return std::result::Result::Ok(crate::BackfillPersistenceOutcome::new(
                    reference,
                    crate::BackfillEntityPersistence::Conflict,
                    crate::BackfillObservationPersistence::NotRecorded,
                ));
            }
            std::result::Result::Err(error)
        },
    };
}

fn map_store_outcome(
    reference: ksp_store_lib::RawTransactionReference,
    outcome: ksp_store_lib::RawAcquisitionWriteOutcome,
) -> ksp_core_lib::Result<crate::BackfillPersistenceOutcome> {
    let entity = outcome.entity();
    let observation = outcome.observation();
    if entity == ksp_store_lib::RawEntityWriteOutcome::Inserted && observation == ksp_store_lib::RawObservationWriteOutcome::Inserted {
        return std::result::Result::Ok(crate::BackfillPersistenceOutcome::new(
            reference,
            crate::BackfillEntityPersistence::Inserted,
            crate::BackfillObservationPersistence::Inserted,
        ));
    }
    if entity == ksp_store_lib::RawEntityWriteOutcome::AlreadyPresent && observation == ksp_store_lib::RawObservationWriteOutcome::Inserted {
        return std::result::Result::Ok(crate::BackfillPersistenceOutcome::new(
            reference,
            crate::BackfillEntityPersistence::AlreadyPresent,
            crate::BackfillObservationPersistence::Inserted,
        ));
    }
    if entity == ksp_store_lib::RawEntityWriteOutcome::AlreadyPresent && observation == ksp_store_lib::RawObservationWriteOutcome::AlreadyPresent {
        return std::result::Result::Ok(crate::BackfillPersistenceOutcome::new(
            reference,
            crate::BackfillEntityPersistence::AlreadyPresent,
            crate::BackfillObservationPersistence::AlreadyPresent,
        ));
    }
    if entity == ksp_store_lib::RawEntityWriteOutcome::SkippedPurged && observation == ksp_store_lib::RawObservationWriteOutcome::NotRecorded {
        return std::result::Result::Ok(crate::BackfillPersistenceOutcome::new(
            reference,
            crate::BackfillEntityPersistence::SkippedPurged,
            crate::BackfillObservationPersistence::NotRecorded,
        ));
    }
    return std::result::Result::Err(persistence_error("store.outcome"));
}

fn persistence_error(field: &'static str) -> ksp_core_lib::Error {
    return ksp_core_lib::Error::new(crate::ERROR_CODE_BACKFILL_PERSISTENCE_INVALID, "invalid Backfill Store persistence state").with_context("field", field);
}

#[cfg(test)]
#[path = "../unit_tests/persistence.rs"]
mod tests;