ic-memory 0.2.0

use crate::{
    key::{StableKey, StableKeyError},
    schema::{SchemaMetadata, SchemaMetadataError},
    slot::{AllocationSlotDescriptor, MemoryManagerSlotError},
};
use serde::{Deserialize, Serialize};
use std::collections::BTreeSet;

const DIAGNOSTIC_STRING_MAX_BYTES: usize = 256;

///
/// AllocationDeclaration
///
/// Checked runtime claim that a stable key should own an allocation slot.
///
/// Declarations are supplied by the current binary before opening storage.
/// Constructors validate the stable key, slot descriptor, label, and schema
/// metadata, but a declaration is not authoritative until it has been validated
/// against the recovered ledger and committed as part of a generation.
#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
pub struct AllocationDeclaration {
    /// Durable stable key.
    pub(crate) stable_key: StableKey,
    /// Claimed allocation slot.
    pub(crate) slot: AllocationSlotDescriptor,
    /// Optional diagnostic label.
    pub(crate) label: Option<String>,
    /// Optional diagnostic schema metadata.
    pub(crate) schema: SchemaMetadata,
}

impl AllocationDeclaration {
    /// Build a declaration from raw parts after validating diagnostic metadata.
    pub fn new(
        stable_key: impl AsRef<str>,
        slot: AllocationSlotDescriptor,
        label: Option<String>,
        schema: SchemaMetadata,
    ) -> Result<Self, DeclarationSnapshotError> {
        let stable_key = StableKey::parse(stable_key).map_err(DeclarationSnapshotError::Key)?;
        validate_label(label.as_deref())?;
        schema
            .validate()
            .map_err(DeclarationSnapshotError::SchemaMetadata)?;
        Ok(Self {
            stable_key,
            slot,
            label,
            schema,
        })
    }

    /// Build a `MemoryManager` declaration with a diagnostic label.
    pub fn memory_manager(
        stable_key: impl AsRef<str>,
        id: u8,
        label: impl Into<String>,
    ) -> Result<Self, DeclarationSnapshotError> {
        Self::memory_manager_with_schema(stable_key, id, label, SchemaMetadata::default())
    }

    /// Build an unlabeled `MemoryManager` declaration.
    pub fn memory_manager_unlabeled(
        stable_key: impl AsRef<str>,
        id: u8,
    ) -> Result<Self, DeclarationSnapshotError> {
        Self::memory_manager_unlabeled_with_schema(stable_key, id, SchemaMetadata::default())
    }

    /// Build a `MemoryManager` declaration with a diagnostic label and schema metadata.
    pub fn memory_manager_with_schema(
        stable_key: impl AsRef<str>,
        id: u8,
        label: impl Into<String>,
        schema: SchemaMetadata,
    ) -> Result<Self, DeclarationSnapshotError> {
        let slot = AllocationSlotDescriptor::memory_manager(id)
            .map_err(DeclarationSnapshotError::MemoryManagerSlot)?;
        Self::new(stable_key, slot, Some(label.into()), schema)
    }

    /// Build an unlabeled `MemoryManager` declaration with schema metadata.
    pub fn memory_manager_unlabeled_with_schema(
        stable_key: impl AsRef<str>,
        id: u8,
        schema: SchemaMetadata,
    ) -> Result<Self, DeclarationSnapshotError> {
        let slot = AllocationSlotDescriptor::memory_manager(id)
            .map_err(DeclarationSnapshotError::MemoryManagerSlot)?;
        Self::new(stable_key, slot, None, schema)
    }

    /// Return the durable stable key claimed by this declaration.
    #[must_use]
    pub const fn stable_key(&self) -> &StableKey {
        &self.stable_key
    }

    /// Return the allocation slot claimed by this declaration.
    #[must_use]
    pub const fn slot(&self) -> &AllocationSlotDescriptor {
        &self.slot
    }

    /// Return the optional diagnostic label.
    #[must_use]
    pub fn label(&self) -> Option<&str> {
        self.label.as_deref()
    }

    /// Return the optional schema metadata.
    #[must_use]
    pub const fn schema(&self) -> &SchemaMetadata {
        &self.schema
    }
}

///
/// DeclarationCollector
///
/// Mutable builder for this binary's allocation declarations.
///
/// The collector is transient runtime state. Sealing rejects duplicate stable
/// keys and duplicate slots within one binary snapshot; historical compatibility
/// is checked later by [`crate::validate_allocations`].
#[derive(Clone, Debug, Default)]
pub struct DeclarationCollector {
    declarations: Vec<AllocationDeclaration>,
}

impl DeclarationCollector {
    /// Create an empty declaration collector.
    #[must_use]
    pub const fn new() -> Self {
        Self {
            declarations: Vec::new(),
        }
    }

    /// Add one allocation declaration.
    pub fn push(&mut self, declaration: AllocationDeclaration) {
        self.declarations.push(declaration);
    }

    /// Add one allocation declaration and return the collector for chaining.
    pub fn declare(&mut self, declaration: AllocationDeclaration) -> &mut Self {
        self.push(declaration);
        self
    }

    /// Add one allocation declaration by value for builder-style chaining.
    #[must_use]
    pub fn with_declaration(mut self, declaration: AllocationDeclaration) -> Self {
        self.push(declaration);
        self
    }

    /// Add a `MemoryManager` declaration with a diagnostic label.
    pub fn declare_memory_manager(
        &mut self,
        stable_key: impl AsRef<str>,
        id: u8,
        label: impl Into<String>,
    ) -> Result<&mut Self, DeclarationSnapshotError> {
        self.declare_memory_manager_with_schema(stable_key, id, label, SchemaMetadata::default())
    }

    /// Add an unlabeled `MemoryManager` declaration.
    pub fn declare_memory_manager_unlabeled(
        &mut self,
        stable_key: impl AsRef<str>,
        id: u8,
    ) -> Result<&mut Self, DeclarationSnapshotError> {
        self.declare_memory_manager_unlabeled_with_schema(stable_key, id, SchemaMetadata::default())
    }

    /// Add a `MemoryManager` declaration with a diagnostic label and schema metadata.
    pub fn declare_memory_manager_with_schema(
        &mut self,
        stable_key: impl AsRef<str>,
        id: u8,
        label: impl Into<String>,
        schema: SchemaMetadata,
    ) -> Result<&mut Self, DeclarationSnapshotError> {
        self.push(AllocationDeclaration::memory_manager_with_schema(
            stable_key, id, label, schema,
        )?);
        Ok(self)
    }

    /// Add an unlabeled `MemoryManager` declaration with schema metadata.
    pub fn declare_memory_manager_unlabeled_with_schema(
        &mut self,
        stable_key: impl AsRef<str>,
        id: u8,
        schema: SchemaMetadata,
    ) -> Result<&mut Self, DeclarationSnapshotError> {
        self.push(AllocationDeclaration::memory_manager_unlabeled_with_schema(
            stable_key, id, schema,
        )?);
        Ok(self)
    }

    /// Add a `MemoryManager` declaration by value for builder-style chaining.
    pub fn with_memory_manager(
        mut self,
        stable_key: impl AsRef<str>,
        id: u8,
        label: impl Into<String>,
    ) -> Result<Self, DeclarationSnapshotError> {
        self.declare_memory_manager(stable_key, id, label)?;
        Ok(self)
    }

    /// Add an unlabeled `MemoryManager` declaration by value for builder-style chaining.
    pub fn with_memory_manager_unlabeled(
        mut self,
        stable_key: impl AsRef<str>,
        id: u8,
    ) -> Result<Self, DeclarationSnapshotError> {
        self.declare_memory_manager_unlabeled(stable_key, id)?;
        Ok(self)
    }

    /// Add a `MemoryManager` declaration with schema metadata by value for builder-style chaining.
    pub fn with_memory_manager_schema(
        mut self,
        stable_key: impl AsRef<str>,
        id: u8,
        label: impl Into<String>,
        schema: SchemaMetadata,
    ) -> Result<Self, DeclarationSnapshotError> {
        self.declare_memory_manager_with_schema(stable_key, id, label, schema)?;
        Ok(self)
    }

    /// Add an unlabeled `MemoryManager` declaration with schema metadata by value.
    pub fn with_memory_manager_unlabeled_schema(
        mut self,
        stable_key: impl AsRef<str>,
        id: u8,
        schema: SchemaMetadata,
    ) -> Result<Self, DeclarationSnapshotError> {
        self.declare_memory_manager_unlabeled_with_schema(stable_key, id, schema)?;
        Ok(self)
    }

    /// Seal collected declarations into a duplicate-free snapshot.
    pub fn seal(self) -> Result<DeclarationSnapshot, DeclarationSnapshotError> {
        DeclarationSnapshot::new(self.declarations)
    }
}

///
/// DeclarationSnapshot
///
/// Immutable runtime declaration snapshot ready for policy and history validation.
///
/// A snapshot is duplicate-free, but it is still not permission to open storage.
/// Integrations should call [`crate::validate_allocations`], commit the staged
/// generation, and only then expose an [`crate::AllocationSession`].
#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
pub struct DeclarationSnapshot {
    /// Runtime declarations.
    declarations: Vec<AllocationDeclaration>,
    /// Optional binary/runtime identity for generation diagnostics.
    runtime_fingerprint: Option<String>,
}

impl DeclarationSnapshot {
    /// Create and validate a declaration snapshot.
    pub fn new(declarations: Vec<AllocationDeclaration>) -> Result<Self, DeclarationSnapshotError> {
        for declaration in &declarations {
            validate_label(declaration.label.as_deref())?;
            declaration
                .schema
                .validate()
                .map_err(DeclarationSnapshotError::SchemaMetadata)?;
        }
        reject_duplicates(&declarations)?;
        Ok(Self {
            declarations,
            runtime_fingerprint: None,
        })
    }

    /// Attach an optional runtime fingerprint.
    pub fn with_runtime_fingerprint(
        mut self,
        fingerprint: impl Into<String>,
    ) -> Result<Self, DeclarationSnapshotError> {
        let fingerprint = fingerprint.into();
        validate_runtime_fingerprint(Some(&fingerprint))?;
        self.runtime_fingerprint = Some(fingerprint);
        Ok(self)
    }

    /// Return true when the snapshot has no declarations.
    #[must_use]
    pub fn is_empty(&self) -> bool {
        self.declarations.is_empty()
    }

    /// Return the number of declarations in the snapshot.
    #[must_use]
    pub fn len(&self) -> usize {
        self.declarations.len()
    }

    /// Borrow the sealed declarations.
    #[must_use]
    pub fn declarations(&self) -> &[AllocationDeclaration] {
        &self.declarations
    }

    /// Borrow the optional runtime fingerprint.
    #[must_use]
    pub fn runtime_fingerprint(&self) -> Option<&str> {
        self.runtime_fingerprint.as_deref()
    }

    pub(crate) fn into_parts(self) -> (Vec<AllocationDeclaration>, Option<String>) {
        (self.declarations, self.runtime_fingerprint)
    }
}

///
/// DeclarationSnapshotError
///
/// Declaration snapshot validation failure.
#[derive(Clone, Debug, Eq, thiserror::Error, PartialEq)]
pub enum DeclarationSnapshotError {
    /// Stable-key grammar failure.
    #[error(transparent)]
    Key(StableKeyError),
    /// `MemoryManager` slot validation failure.
    #[error(transparent)]
    MemoryManagerSlot(MemoryManagerSlotError),
    /// Schema metadata encoding failure.
    #[error(transparent)]
    SchemaMetadata(SchemaMetadataError),
    /// A stable key appeared more than once in one snapshot.
    #[error("stable key '{0}' is declared more than once")]
    DuplicateStableKey(StableKey),
    /// An allocation slot appeared more than once in one snapshot.
    #[error("allocation slot '{0:?}' is declared more than once")]
    DuplicateSlot(AllocationSlotDescriptor),
    /// Present declaration labels must be non-empty.
    #[error("allocation declaration label must not be empty when present")]
    EmptyLabel,
    /// Declaration labels must stay bounded for durable ledger storage.
    #[error("allocation declaration label must be at most 256 bytes")]
    LabelTooLong,
    /// Declaration labels must not require Unicode normalization.
    #[error("allocation declaration label must be ASCII")]
    NonAsciiLabel,
    /// Declaration labels must be printable metadata.
    #[error("allocation declaration label must not contain ASCII control characters")]
    ControlCharacterLabel,
    /// Present runtime fingerprints must be non-empty.
    #[error("runtime_fingerprint must not be empty when present")]
    EmptyRuntimeFingerprint,
    /// Runtime fingerprints must stay bounded for durable ledger storage.
    #[error("runtime_fingerprint must be at most 256 bytes")]
    RuntimeFingerprintTooLong,
    /// Runtime fingerprints must not require Unicode normalization.
    #[error("runtime_fingerprint must be ASCII")]
    NonAsciiRuntimeFingerprint,
    /// Runtime fingerprints must be printable metadata.
    #[error("runtime_fingerprint must not contain ASCII control characters")]
    ControlCharacterRuntimeFingerprint,
}

fn validate_label(label: Option<&str>) -> Result<(), DeclarationSnapshotError> {
    let Some(label) = label else {
        return Ok(());
    };
    if label.is_empty() {
        return Err(DeclarationSnapshotError::EmptyLabel);
    }
    if label.len() > DIAGNOSTIC_STRING_MAX_BYTES {
        return Err(DeclarationSnapshotError::LabelTooLong);
    }
    if !label.is_ascii() {
        return Err(DeclarationSnapshotError::NonAsciiLabel);
    }
    if label.bytes().any(|byte| byte.is_ascii_control()) {
        return Err(DeclarationSnapshotError::ControlCharacterLabel);
    }
    Ok(())
}

pub(crate) fn validate_runtime_fingerprint(
    fingerprint: Option<&str>,
) -> Result<(), DeclarationSnapshotError> {
    let Some(fingerprint) = fingerprint else {
        return Ok(());
    };
    if fingerprint.is_empty() {
        return Err(DeclarationSnapshotError::EmptyRuntimeFingerprint);
    }
    if fingerprint.len() > DIAGNOSTIC_STRING_MAX_BYTES {
        return Err(DeclarationSnapshotError::RuntimeFingerprintTooLong);
    }
    if !fingerprint.is_ascii() {
        return Err(DeclarationSnapshotError::NonAsciiRuntimeFingerprint);
    }
    if fingerprint.bytes().any(|byte| byte.is_ascii_control()) {
        return Err(DeclarationSnapshotError::ControlCharacterRuntimeFingerprint);
    }
    Ok(())
}

fn reject_duplicates(
    declarations: &[AllocationDeclaration],
) -> Result<(), DeclarationSnapshotError> {
    let mut keys = BTreeSet::new();
    let mut slots = BTreeSet::new();

    for declaration in declarations {
        if !slots.insert(declaration.slot.clone()) {
            return Err(DeclarationSnapshotError::DuplicateSlot(
                declaration.slot.clone(),
            ));
        }
        if !keys.insert(declaration.stable_key.clone()) {
            return Err(DeclarationSnapshotError::DuplicateStableKey(
                declaration.stable_key.clone(),
            ));
        }
    }

    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::slot::AllocationSlotDescriptor;

    fn declaration(key: &str, id: u8) -> AllocationDeclaration {
        AllocationDeclaration::new(
            key,
            AllocationSlotDescriptor::memory_manager(id).expect("usable slot"),
            None,
            SchemaMetadata::default(),
        )
        .expect("declaration")
    }

    #[test]
    fn declaration_rejects_unbounded_label_metadata() {
        let err = AllocationDeclaration::new(
            "app.users.v1",
            AllocationSlotDescriptor::memory_manager(100).expect("usable slot"),
            Some("x".repeat(257)),
            SchemaMetadata::default(),
        )
        .expect_err("label too long");

        assert_eq!(err, DeclarationSnapshotError::LabelTooLong);
    }

    #[test]
    fn memory_manager_declaration_constructor_builds_common_declaration() {
        let declaration = AllocationDeclaration::memory_manager("app.orders.v1", 100, "orders")
            .expect("declaration");

        assert_eq!(declaration.stable_key.as_str(), "app.orders.v1");
        assert_eq!(
            declaration.slot,
            AllocationSlotDescriptor::memory_manager(100).expect("usable slot")
        );
        assert_eq!(declaration.label.as_deref(), Some("orders"));
        assert_eq!(declaration.schema, SchemaMetadata::default());
    }

    #[test]
    fn memory_manager_declaration_constructor_rejects_invalid_slot() {
        let err = AllocationDeclaration::memory_manager("app.orders.v1", u8::MAX, "orders")
            .expect_err("sentinel must fail");

        assert!(matches!(
            err,
            DeclarationSnapshotError::MemoryManagerSlot(_)
        ));
    }

    #[test]
    fn declaration_collector_declares_memory_manager_allocations() {
        let mut declarations = DeclarationCollector::new();
        declarations
            .declare_memory_manager("app.orders.v1", 100, "orders")
            .expect("orders declaration")
            .declare_memory_manager_unlabeled("app.users.v1", 101)
            .expect("users declaration");

        let snapshot = declarations.seal().expect("snapshot");

        assert_eq!(snapshot.len(), 2);
        assert_eq!(
            snapshot.declarations()[0].slot,
            AllocationSlotDescriptor::memory_manager(100).expect("usable slot")
        );
        assert_eq!(snapshot.declarations()[0].label.as_deref(), Some("orders"));
        assert_eq!(snapshot.declarations()[1].label, None);
    }

    #[test]
    fn declaration_collector_builder_declares_memory_manager_allocations() {
        let snapshot = DeclarationCollector::new()
            .with_memory_manager("app.orders.v1", 100, "orders")
            .expect("orders declaration")
            .with_memory_manager_unlabeled("app.users.v1", 101)
            .expect("users declaration")
            .seal()
            .expect("snapshot");

        assert_eq!(snapshot.len(), 2);
    }

    #[test]
    fn snapshot_rejects_unbounded_runtime_fingerprint() {
        let snapshot =
            DeclarationSnapshot::new(vec![declaration("app.users.v1", 100)]).expect("snapshot");

        let err = snapshot
            .with_runtime_fingerprint("x".repeat(257))
            .expect_err("fingerprint too long");

        assert_eq!(err, DeclarationSnapshotError::RuntimeFingerprintTooLong);
    }

    #[test]
    fn rejects_duplicate_keys() {
        let err = DeclarationSnapshot::new(vec![
            declaration("app.users.v1", 100),
            declaration("app.users.v1", 101),
        ])
        .expect_err("duplicate key");

        assert!(matches!(
            err,
            DeclarationSnapshotError::DuplicateStableKey(_)
        ));
    }

    #[test]
    fn rejects_duplicate_slots() {
        let err = DeclarationSnapshot::new(vec![
            declaration("app.users.v1", 100),
            declaration("app.orders.v1", 100),
        ])
        .expect_err("duplicate slot");

        assert!(matches!(err, DeclarationSnapshotError::DuplicateSlot(_)));
    }
}