syntax = "proto3";
package waymaker.cache;

option go_package = "/apis/waymaker_cache";

// ============================================================
// WaymakerCacheService — generic TTL / eviction layer over any
// bucket-shaped store (KV, Hash, Set). Methods are deliberately
// minimal at this stage; the design will land alongside the
// first concrete eviction policy (LRU, ARC, expiry-driven).
//
// Phase-5 milestone:
//   - This proto pins the crate layout + the wire namespace
//     (`waymaker.cache`) so clients don't need to migrate when
//     real handlers ship.
//   - The server registers the service but every RPC returns
//     `Unimplemented` until the policy work lands.
// ============================================================

service WaymakerCacheService {
  // Apply a TTL policy to a bucket. `policy_id` selects from
  // server-configured policies (initially: `lru`, `expiry`).
  rpc AttachPolicy (AttachPolicyRequest) returns (AttachPolicyResponse);

  // Detach the policy currently bound to `bucket` (no-op if
  // none).
  rpc DetachPolicy (DetachPolicyRequest) returns (DetachPolicyResponse);

  // Report current cache stats (hit/miss/eviction counters,
  // memory footprint) for a bucket.
  rpc Stats (StatsRequest) returns (StatsResponse);
}

message AttachPolicyRequest {
  string bucket = 1;
  string policy_id = 2;
  // Policy-specific knobs (e.g. `max_entries`, `default_ttl_ms`)
  // — interpretation is server-side.
  map<string, string> params = 3;
}
message AttachPolicyResponse {
  bool success = 1;
  string result_code = 2;
  string message = 3;
}

message DetachPolicyRequest { string bucket = 1; }
message DetachPolicyResponse {
  bool success = 1;
  string result_code = 2;
  string message = 3;
}

message StatsRequest { string bucket = 1; }
message StatsResponse {
  bool success = 1;
  string result_code = 2;
  string message = 3;
  uint64 hit_count = 4;
  uint64 miss_count = 5;
  uint64 eviction_count = 6;
  uint64 size_bytes = 7;
  uint64 entry_count = 8;
}