// file: crates/ksp-job-backfill-lib/src/request.rs
// version: 6

use sha2::Digest; // rust-rules: trait-import

/// Maximum number of transaction candidates admitted by one bounded Backfill Job.
pub const MAX_BACKFILL_CANDIDATES: usize = 10_000;
/// Maximum number of concurrent transaction hydrations admitted by one Backfill request.
pub const MAX_BACKFILL_HYDRATION_CONCURRENCY: usize = 64;
/// Maximum number of `getSignaturesForAddress` pages admitted by one address Backfill request.
pub const MAX_BACKFILL_PAGES: usize = 10_000;
/// Maximum page size admitted for one `getSignaturesForAddress` request.
pub const MAX_BACKFILL_PAGE_SIZE: usize = 1_000;
/// Maximum Base58 text length possible for one canonical 64-byte Solana signature.
pub const MAX_BACKFILL_SIGNATURE_TEXT_BYTES: usize = 88;
/// Minimum Base58 text length possible for one canonical 64-byte Solana signature.
pub const MIN_BACKFILL_SIGNATURE_TEXT_BYTES: usize = 64;

/// Commitment levels intentionally admitted by the historical Backfill vertical.
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub enum BackfillCommitment {
    /// Read history at Solana `confirmed` commitment.
    Confirmed,
    /// Read history at Solana `finalized` commitment.
    Finalized,
}

impl crate::BackfillCommitment {
    /// Returns the stable Backfill commitment code.
    #[must_use]
    pub const fn code(self) -> &'static str {
        return match self {
            Self::Confirmed => "confirmed",
            Self::Finalized => "finalized",
        };
    }

    /// Maps the narrowed Backfill commitment to the Transport-owned Solana commitment.
    #[must_use]
    pub(crate) const fn transport(self) -> ksp_onchain_transport_lib::SolanaCommitment {
        return match self {
            Self::Confirmed => ksp_onchain_transport_lib::SolanaCommitment::Confirmed,
            Self::Finalized => ksp_onchain_transport_lib::SolanaCommitment::Finalized,
        };
    }
}

/// Bounded Base58-shaped transaction signature text used by discovery and RAW conversion.
///
/// Construction validates the encoded shape required by discovery. Exact conversion to the
/// Store-owned 64-byte signature is available through [`Self::to_raw_transaction_signature`].
#[derive(Clone, Eq, Hash, Ord, PartialEq, PartialOrd)]
pub struct BackfillSignature(std::string::String);

impl crate::BackfillSignature {
    /// Creates one bounded Base58-shaped signature text.
    pub fn new(value: impl std::convert::Into<std::string::String>) -> ksp_core_lib::Result<Self> {
        let value = value.into();
        if !valid_signature_text(value.as_str()) {
            return std::result::Result::Err(signature_error());
        }
        return std::result::Result::Ok(Self(value));
    }

    /// Returns the validated encoded signature text.
    #[must_use]
    pub fn as_str(&self) -> &str {
        return self.0.as_str();
    }

    /// Decodes this Base58 text to the exact Store-owned 64-byte Solana signature.
    pub fn to_raw_transaction_signature(&self) -> ksp_core_lib::Result<ksp_store_lib::RawTransactionSignature> {
        return crate::decode_backfill_signature(self);
    }
}

impl std::fmt::Debug for crate::BackfillSignature {
    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        return formatter.write_str("BackfillSignature(..)");
    }
}

/// Stable category of one bounded Backfill discovery scope.
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub enum BackfillScopeKind {
    /// Read the current newest address window.
    LatestAddress,
    /// Read address history older than one exclusive anchor.
    BeforeAddress,
    /// Read the bounded newer window closest to one exclusive anchor.
    AfterAddress,
    /// Hydrate an explicit bounded signature list without address discovery.
    ExplicitSignatures,
}

impl crate::BackfillScopeKind {
    /// Returns the stable scope code used by diagnostics and scope fingerprinting.
    #[must_use]
    pub const fn code(self) -> &'static str {
        return match self {
            Self::LatestAddress => "latest_address",
            Self::BeforeAddress => "before_address",
            Self::AfterAddress => "after_address",
            Self::ExplicitSignatures => "explicit_signatures",
        };
    }
}

#[derive(Clone, Eq, PartialEq)]
enum BackfillScopeValue {
    LatestAddress { address: ksp_core_lib::Pubkey },
    BeforeAddress { address: ksp_core_lib::Pubkey, anchor: crate::BackfillSignature },
    AfterAddress { address: ksp_core_lib::Pubkey, anchor: crate::BackfillSignature },
    ExplicitSignatures { signatures: std::vec::Vec<crate::BackfillSignature> },
}

/// Validated bounded discovery scope for one historical Backfill Job.
#[derive(Clone, Eq, PartialEq)]
pub struct BackfillScope {
    value: BackfillScopeValue,
}

impl crate::BackfillScope {
    /// Creates a scope starting at the newest known history for one address.
    #[must_use]
    pub const fn latest_address(address: ksp_core_lib::Pubkey) -> Self {
        return Self { value: BackfillScopeValue::LatestAddress { address } };
    }

    /// Creates a scope reading history older than one exclusive address anchor.
    #[must_use]
    pub fn before_address(address: ksp_core_lib::Pubkey, anchor: crate::BackfillSignature) -> Self {
        return Self { value: BackfillScopeValue::BeforeAddress { address, anchor } };
    }

    /// Creates a scope reading the bounded newer history closest to one exclusive address anchor.
    #[must_use]
    pub fn after_address(address: ksp_core_lib::Pubkey, anchor: crate::BackfillSignature) -> Self {
        return Self { value: BackfillScopeValue::AfterAddress { address, anchor } };
    }

    /// Creates an explicit signature scope with stable first-occurrence deduplication.
    pub fn explicit_signatures(signatures: std::vec::Vec<crate::BackfillSignature>) -> ksp_core_lib::Result<Self> {
        if signatures.is_empty() || signatures.len() > crate::MAX_BACKFILL_CANDIDATES {
            return std::result::Result::Err(request_error("scope.signatures"));
        }
        let mut unique = std::vec::Vec::with_capacity(signatures.len());
        let mut seen = std::collections::HashSet::with_capacity(signatures.len());
        for signature in signatures {
            if seen.insert(signature.clone()) {
                unique.push(signature);
            }
        }
        if unique.is_empty() {
            return std::result::Result::Err(request_error("scope.signatures"));
        }
        return std::result::Result::Ok(Self { value: BackfillScopeValue::ExplicitSignatures { signatures: unique } });
    }

    /// Returns the stable category of this scope.
    #[must_use]
    pub const fn kind(&self) -> crate::BackfillScopeKind {
        return match &self.value {
            BackfillScopeValue::LatestAddress { .. } => crate::BackfillScopeKind::LatestAddress,
            BackfillScopeValue::BeforeAddress { .. } => crate::BackfillScopeKind::BeforeAddress,
            BackfillScopeValue::AfterAddress { .. } => crate::BackfillScopeKind::AfterAddress,
            BackfillScopeValue::ExplicitSignatures { .. } => crate::BackfillScopeKind::ExplicitSignatures,
        };
    }

    /// Returns the address used by address scopes.
    #[must_use]
    pub const fn address(&self) -> std::option::Option<&ksp_core_lib::Pubkey> {
        return match &self.value {
            BackfillScopeValue::LatestAddress { address }
            | BackfillScopeValue::BeforeAddress { address, .. }
            | BackfillScopeValue::AfterAddress { address, .. } => std::option::Option::Some(address),
            BackfillScopeValue::ExplicitSignatures { .. } => std::option::Option::None,
        };
    }

    /// Returns the exclusive anchor used by before/after scopes.
    #[must_use]
    pub const fn anchor(&self) -> std::option::Option<&crate::BackfillSignature> {
        return match &self.value {
            BackfillScopeValue::BeforeAddress { anchor, .. } | BackfillScopeValue::AfterAddress { anchor, .. } => std::option::Option::Some(anchor),
            BackfillScopeValue::LatestAddress { .. } | BackfillScopeValue::ExplicitSignatures { .. } => std::option::Option::None,
        };
    }

    /// Returns the stable deduplicated explicit signature list, when this is an explicit scope.
    #[must_use]
    pub fn signatures(&self) -> std::option::Option<&[crate::BackfillSignature]> {
        return match &self.value {
            BackfillScopeValue::ExplicitSignatures { signatures } => std::option::Option::Some(signatures.as_slice()),
            BackfillScopeValue::LatestAddress { .. } | BackfillScopeValue::BeforeAddress { .. } | BackfillScopeValue::AfterAddress { .. } => {
                std::option::Option::None
            },
        };
    }
}

impl std::fmt::Debug for crate::BackfillScope {
    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let mut debug = formatter.debug_struct("BackfillScope");
        debug.field("kind", &self.kind());
        match &self.value {
            BackfillScopeValue::LatestAddress { address } => {
                debug.field("address", address);
            },
            BackfillScopeValue::BeforeAddress { address, .. } | BackfillScopeValue::AfterAddress { address, .. } => {
                debug.field("address", address).field("anchor", &"<redacted>");
            },
            BackfillScopeValue::ExplicitSignatures { signatures } => {
                debug.field("signature_count", &signatures.len());
            },
        }
        return debug.finish();
    }
}

/// Opaque deterministic fingerprint of one semantic Backfill scope.
#[derive(Clone, Copy, Eq, Hash, PartialEq)]
pub struct BackfillScopeFingerprint([u8; 32]);

impl crate::BackfillScopeFingerprint {
    const fn from_bytes(bytes: [u8; 32]) -> Self {
        return Self(bytes);
    }

    /// Returns the exact deterministic fingerprint bytes.
    #[must_use]
    pub const fn as_bytes(&self) -> &[u8; 32] {
        return &self.0;
    }
}

impl std::fmt::Debug for crate::BackfillScopeFingerprint {
    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        return formatter.write_str("BackfillScopeFingerprint(..)");
    }
}

/// Fully explicit bounded request for one historical transaction Backfill Job.
#[derive(Clone, Eq, PartialEq)]
pub struct BackfillRequest {
    job_id: ksp_job_api::JobId,
    network: ksp_store_lib::RawNetworkId,
    role: ksp_onchain_transport_lib::HttpRoleName,
    commitment: crate::BackfillCommitment,
    scope: crate::BackfillScope,
    page_size: usize,
    max_pages: usize,
    max_candidates: usize,
    hydration_concurrency: usize,
    min_context_slot: std::option::Option<u64>,
    scope_fingerprint: crate::BackfillScopeFingerprint,
    checkpoint: std::option::Option<crate::BackfillCheckpoint>,
}

impl crate::BackfillRequest {
    /// Creates and validates one fully explicit bounded Backfill request.
    #[allow(clippy::too_many_arguments)]
    pub fn new(
        job_id: ksp_job_api::JobId,
        network: ksp_store_lib::RawNetworkId,
        role: ksp_onchain_transport_lib::HttpRoleName,
        commitment: crate::BackfillCommitment,
        scope: crate::BackfillScope,
        page_size: usize,
        max_pages: usize,
        max_candidates: usize,
        hydration_concurrency: usize,
        min_context_slot: std::option::Option<u64>,
    ) -> ksp_core_lib::Result<Self> {
        if page_size == 0 || page_size > crate::MAX_BACKFILL_PAGE_SIZE {
            return std::result::Result::Err(request_error("page_size"));
        }
        if max_pages == 0 || max_pages > crate::MAX_BACKFILL_PAGES {
            return std::result::Result::Err(request_error("max_pages"));
        }
        if max_candidates == 0 || max_candidates > crate::MAX_BACKFILL_CANDIDATES {
            return std::result::Result::Err(request_error("max_candidates"));
        }
        if hydration_concurrency == 0 || hydration_concurrency > crate::MAX_BACKFILL_HYDRATION_CONCURRENCY {
            return std::result::Result::Err(request_error("hydration_concurrency"));
        }
        if role.as_str().is_empty() || role.as_str().trim() != role.as_str() {
            return std::result::Result::Err(request_error("role"));
        }
        if scope.kind() == crate::BackfillScopeKind::ExplicitSignatures {
            if min_context_slot.is_some() {
                return std::result::Result::Err(request_error("min_context_slot"));
            }
            let signature_count = match scope.signatures() {
                std::option::Option::Some(signatures) => signatures.len(),
                std::option::Option::None => return std::result::Result::Err(request_error("scope.signatures")),
            };
            if signature_count > max_candidates {
                return std::result::Result::Err(request_error("max_candidates"));
            }
        }
        let scope_fingerprint = fingerprint_scope(&network, commitment, &scope, page_size, max_pages, max_candidates, min_context_slot);
        return std::result::Result::Ok(Self {
            job_id,
            network,
            role,
            commitment,
            scope,
            page_size,
            max_pages,
            max_candidates,
            hydration_concurrency,
            min_context_slot,
            scope_fingerprint,
            checkpoint: std::option::Option::None,
        });
    }

    /// Returns the caller-owned logical Job identity.
    #[must_use]
    pub const fn job_id(&self) -> &ksp_job_api::JobId {
        return &self.job_id;
    }

    /// Returns the Store-scoped logical network identity for every candidate in this Job.
    #[must_use]
    pub const fn network(&self) -> &ksp_store_lib::RawNetworkId {
        return &self.network;
    }

    /// Returns the logical HTTP role used only for Transport selection.
    #[must_use]
    pub const fn role(&self) -> &ksp_onchain_transport_lib::HttpRoleName {
        return &self.role;
    }

    /// Returns the narrowed commitment used by discovery and hydration.
    #[must_use]
    pub const fn commitment(&self) -> crate::BackfillCommitment {
        return self.commitment;
    }

    /// Returns the validated discovery scope.
    #[must_use]
    pub const fn scope(&self) -> &crate::BackfillScope {
        return &self.scope;
    }

    /// Returns the per-request signature page size.
    #[must_use]
    pub const fn page_size(&self) -> usize {
        return self.page_size;
    }

    /// Returns the maximum number of address pages admitted by this Job.
    #[must_use]
    pub const fn max_pages(&self) -> usize {
        return self.max_pages;
    }

    /// Returns the maximum number of transaction candidates admitted by this Job.
    #[must_use]
    pub const fn max_candidates(&self) -> usize {
        return self.max_candidates;
    }

    /// Returns the future hydration concurrency bound.
    #[must_use]
    pub const fn hydration_concurrency(&self) -> usize {
        return self.hydration_concurrency;
    }

    /// Returns the optional Solana minimum context slot used by address discovery.
    #[must_use]
    pub const fn min_context_slot(&self) -> std::option::Option<u64> {
        return self.min_context_slot;
    }

    /// Returns the deterministic semantic scope fingerprint.
    ///
    /// Transport role, provider, endpoint and protocol are deliberately excluded. They describe
    /// acquisition provenance, not transaction or scope identity.
    #[must_use]
    pub const fn scope_fingerprint(&self) -> crate::BackfillScopeFingerprint {
        return self.scope_fingerprint;
    }

    /// Attaches one caller-owned checkpoint after validating Job and semantic scope identity.
    pub fn with_checkpoint(mut self, checkpoint: crate::BackfillCheckpoint) -> ksp_core_lib::Result<Self> {
        let validation = crate::validate_request_checkpoint(&self.job_id, self.scope_fingerprint, self.scope.kind(), &checkpoint);
        if let std::result::Result::Err(error) = validation {
            return std::result::Result::Err(error);
        }
        self.checkpoint = std::option::Option::Some(checkpoint);
        return std::result::Result::Ok(self);
    }

    /// Reissues a validated checkpoint onto a new Job lifecycle while preserving exact request semantics.
    pub fn resume_for_job(&self, job_id: ksp_job_api::JobId, checkpoint: crate::BackfillCheckpoint) -> ksp_core_lib::Result<Self> {
        let validation = crate::validate_request_checkpoint(&self.job_id, self.scope_fingerprint, self.scope.kind(), &checkpoint);
        if let std::result::Result::Err(error) = validation {
            return std::result::Result::Err(error);
        }
        let checkpoint = checkpoint.reissue_for_job(job_id.clone());
        let mut resumed = self.clone();
        resumed.job_id = job_id;
        resumed.checkpoint = std::option::Option::None;
        return resumed.with_checkpoint(checkpoint);
    }

    /// Returns the validated optional checkpoint supplied for controlled resumption.
    #[must_use]
    pub const fn checkpoint(&self) -> std::option::Option<&crate::BackfillCheckpoint> {
        return self.checkpoint.as_ref();
    }
}

impl std::fmt::Debug for crate::BackfillRequest {
    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        return formatter
            .debug_struct("BackfillRequest")
            .field("job_id", &self.job_id)
            .field("network", &self.network)
            .field("role", &self.role)
            .field("commitment", &self.commitment)
            .field("scope", &self.scope)
            .field("page_size", &self.page_size)
            .field("max_pages", &self.max_pages)
            .field("max_candidates", &self.max_candidates)
            .field("hydration_concurrency", &self.hydration_concurrency)
            .field("min_context_slot", &self.min_context_slot)
            .field("scope_fingerprint", &self.scope_fingerprint)
            .field("has_checkpoint", &self.checkpoint.is_some())
            .finish();
    }
}

fn fingerprint_scope(
    network: &ksp_store_lib::RawNetworkId,
    commitment: crate::BackfillCommitment,
    scope: &crate::BackfillScope,
    page_size: usize,
    max_pages: usize,
    max_candidates: usize,
    min_context_slot: std::option::Option<u64>,
) -> crate::BackfillScopeFingerprint {
    let mut hasher = sha2::Sha256::new();
    hasher.update(b"ksp.job.backfill.scope.v1\0");
    hash_bytes(&mut hasher, network.as_str().as_bytes());
    hash_bytes(&mut hasher, commitment.code().as_bytes());
    hash_bytes(&mut hasher, scope.kind().code().as_bytes());
    if let std::option::Option::Some(address) = scope.address() {
        hash_bytes(&mut hasher, address.as_ref());
    }
    if let std::option::Option::Some(anchor) = scope.anchor() {
        hash_bytes(&mut hasher, anchor.as_str().as_bytes());
    }
    if let std::option::Option::Some(signatures) = scope.signatures() {
        for signature in signatures {
            hash_bytes(&mut hasher, signature.as_str().as_bytes());
        }
    }
    hash_u64(&mut hasher, page_size as u64);
    hash_u64(&mut hasher, max_pages as u64);
    hash_u64(&mut hasher, max_candidates as u64);
    match min_context_slot {
        std::option::Option::Some(slot) => {
            hasher.update([1_u8]);
            hash_u64(&mut hasher, slot);
        },
        std::option::Option::None => hasher.update([0_u8]),
    }
    let bytes: [u8; 32] = hasher.finalize().into();
    return crate::BackfillScopeFingerprint::from_bytes(bytes);
}

fn hash_bytes(hasher: &mut sha2::Sha256, value: &[u8]) {
    hash_u64(hasher, value.len() as u64);
    hasher.update(value);
}

fn hash_u64(hasher: &mut sha2::Sha256, value: u64) {
    hasher.update(value.to_be_bytes());
}

fn request_error(field: &'static str) -> ksp_core_lib::Error {
    return ksp_core_lib::Error::new(crate::ERROR_CODE_BACKFILL_REQUEST_INVALID, "invalid bounded Backfill request").with_context("field", field);
}

fn signature_error() -> ksp_core_lib::Error {
    return ksp_core_lib::Error::new(crate::ERROR_CODE_BACKFILL_SIGNATURE_INVALID, "invalid bounded Backfill transaction signature")
        .with_context("field", "signature");
}

fn valid_signature_text(value: &str) -> bool {
    if value.len() < crate::MIN_BACKFILL_SIGNATURE_TEXT_BYTES || value.len() > crate::MAX_BACKFILL_SIGNATURE_TEXT_BYTES {
        return false;
    }
    return value.bytes().all(|byte| {
        return matches!(byte, b'1'..=b'9' | b'A'..=b'H' | b'J'..=b'N' | b'P'..=b'Z' | b'a'..=b'k' | b'm'..=b'z');
    });
}

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