safe-migrate 0.5.0

// FILE: src/db/cache.rs
use crate::ast::identifiers::ObjectId;
use crate::model::constraint::ConstraintState;
use crate::model::function::FunctionState;
use crate::model::relation::RelationState;
use crate::model::role::RoleState;
use crate::model::schema::SchemaState;
use crate::model::sequence::SequenceState;
use crate::model::trigger::TriggerEnableMode;
use crate::model::types::TypeState;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct ForeignKeyCache {
    pub constraint_name: String,
    pub from_table: ObjectId,
    pub to_table: ObjectId,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct IndexCache {
    pub index_id: ObjectId,
    pub table_id: ObjectId,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct TriggerCache {
    pub trigger_id: ObjectId,
    pub table_id: ObjectId,
    pub function_id: ObjectId,
    pub enabled_mode: TriggerEnableMode,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DependencyCache {
    pub classid: u32,
    pub objid: u32,
    pub objsubid: i32,
    pub refclassid: u32,
    pub refobjid: u32,
    pub refobjsubid: i32,
    pub deptype: String,
    pub obj_schema: Option<String>,
    pub obj_name: Option<String>,
    pub ref_schema: Option<String>,
    pub ref_name: Option<String>,
}

#[derive(Debug, Clone, Serialize, Deserialize, Default)]
pub struct CacheMetadata {
    /// Seconds since the Unix epoch when `safe-migrate sync` assembled this
    /// baseline. `None` represents a cache written before provenance support.
    pub created_at_unix_secs: Option<u64>,
    /// PostgreSQL database name only; connection credentials and host details
    /// are deliberately never stored in a cache.
    pub source_database: Option<String>,
    /// Session role used when the cache was synchronized. This is needed to
    /// resolve PostgreSQL's special `$user` search-path entry.
    pub source_role: Option<String>,
    /// `SESSION_USER` at synchronization time. This remains distinct from
    /// `source_role` when the connection has selected another effective role.
    pub source_session_role: Option<String>,
    /// Parsed `search_path` setting before PostgreSQL expands `$user`.
    pub source_search_path: Option<Vec<String>>,
    /// Explicit schema scope passed to sync. `None` means all non-system
    /// schemas were requested.
    pub schemas: Option<Vec<String>>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DbCache {
    pub pg_version_num: Option<u32>,
    pub metadata: CacheMetadata,
    pub search_path: Vec<String>,
    pub relations: HashMap<ObjectId, RelationState>,
    pub foreign_keys: Vec<ForeignKeyCache>,
    pub indexes: Vec<IndexCache>,
    pub constraints: Vec<ConstraintState>,
    pub triggers: Vec<TriggerCache>,
    pub functions: HashMap<ObjectId, FunctionState>,
    pub types: HashMap<ObjectId, TypeState>,
    pub roles: HashMap<ObjectId, RoleState>,
    pub schemas: HashMap<String, SchemaState>,
    pub sequences: HashMap<ObjectId, SequenceState>,
    pub dependencies: Vec<DependencyCache>,
}

pub const CACHE_FORMAT_VERSION: u32 = 5;

pub const CACHE_V5_MAGIC: &[u8] = b"SMCACHE05";

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum DbCacheVersioned {
    // Unit variants reserve the historic bincode discriminants. The reader
    // rejects non-V5 headers before decoding, so legacy layouts are not part
    // of the production model and cannot be converted accidentally.
    V1,
    V2,
    V3,
    V4,
    V5(Box<DbCache>),
}

impl DbCacheVersioned {
    pub fn format_version(&self) -> u32 {
        match self {
            DbCacheVersioned::V1 => 1,
            DbCacheVersioned::V2 => 2,
            DbCacheVersioned::V3 => 3,
            DbCacheVersioned::V4 => 4,
            DbCacheVersioned::V5(_) => 5,
        }
    }

    pub fn into_cache(self) -> Result<DbCache, String> {
        match self {
            DbCacheVersioned::V1
            | DbCacheVersioned::V2
            | DbCacheVersioned::V3
            | DbCacheVersioned::V4 => Err(
                "This cache format is unsupported. Run `safe-migrate sync` to rebuild it."
                    .to_string(),
            ),
            DbCacheVersioned::V5(c) => Ok(*c),
        }
    }
}

impl Default for DbCache {
    fn default() -> Self {
        Self::new()
    }
}

impl DbCache {
    pub fn new() -> Self {
        Self {
            pg_version_num: None,
            metadata: CacheMetadata::default(),
            search_path: vec!["public".to_string()],
            relations: HashMap::new(),
            foreign_keys: Vec::new(),
            indexes: Vec::new(),
            constraints: Vec::new(),
            triggers: Vec::new(),
            functions: HashMap::new(),
            types: HashMap::new(),
            roles: HashMap::new(),
            schemas: HashMap::new(),
            sequences: HashMap::new(),
            dependencies: Vec::new(),
        }
    }

    pub fn insert_baseline(&mut self, id: ObjectId, state: RelationState) {
        self.relations.insert(id, state);
    }

    pub fn baseline_relations(&self) -> impl Iterator<Item = (&ObjectId, &RelationState)> {
        self.relations.iter()
    }
}

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

    #[test]
    fn every_legacy_cache_variant_is_rejected_generically() {
        for (versioned, expected_version) in [
            (DbCacheVersioned::V1, 1),
            (DbCacheVersioned::V2, 2),
            (DbCacheVersioned::V3, 3),
            (DbCacheVersioned::V4, 4),
        ] {
            assert_eq!(versioned.format_version(), expected_version);
            assert_eq!(
                versioned.into_cache().unwrap_err(),
                "This cache format is unsupported. Run `safe-migrate sync` to rebuild it."
            );
        }
    }

    #[test]
    fn current_cache_format_is_v5() {
        assert_eq!(CACHE_FORMAT_VERSION, 5);
        assert_eq!(DbCacheVersioned::V5(Box::default()).format_version(), 5);
        assert_eq!(CACHE_V5_MAGIC, b"SMCACHE05");
    }
}