syntax = "proto3";

package komp_ac.ecb;

// Read-only access to ECB conversion previews and audit evidence.
//
// This service exists for manual visual verification before and after posting.
// Preview performs the authoritative unrounded backend calculation without
// writing; evidence exposes conversions already recorded by posting workflows.
service EcbService {
  // Preview the exact conversion the backend would currently perform.
  // This reads local verified ECB data and never persists conversion evidence.
  rpc PreviewEcbConversion(PreviewEcbConversionRequest)
      returns (PreviewEcbConversionResponse);

  // List immutable ECB conversion evidence for one money value.
  rpc ListEcbConversionEvidence(ListEcbConversionEvidenceRequest)
      returns (ListEcbConversionEvidenceResponse);

  // Health of the reference-rate import pipeline: how far verified coverage
  // reaches, how far it should reach by now, and how the recent import
  // attempts went. Not profile-scoped -- one pipeline feeds every profile.
  rpc GetEcbPipelineStatus(GetEcbPipelineStatusRequest)
      returns (GetEcbPipelineStatusResponse);
}

message GetEcbPipelineStatusRequest {
  // Optional. How many recent import attempts to return. Zero uses 20; the
  // maximum is 100.
  int32 batch_limit = 1;
}

// One row of the append-only import audit log.
message EcbImportBatch {
  int64 batch_id = 1;
  // "running", "succeeded" or "failed".
  string status = 2;
  string requested_from = 3;
  string requested_through = 4;
  string endpoint = 5;
  string started_at = 6;
  optional string completed_at = 7;
  // Present on a batch that advanced coverage.
  optional string verified_through_date = 8;
  optional int32 observation_count = 9;
  // May be lower than observation_count: an observation already recorded by an
  // earlier batch is kept rather than replaced.
  optional int32 inserted_observation_count = 10;
  optional string error_message = 11;
}

message GetEcbPipelineStatusResponse {
  // Latest date a successful batch verified. Absent when nothing has ever
  // succeeded, which is what a pipeline that has never run looks like.
  optional string verified_through_date = 1;

  // The date coverage should have reached by now, derived from the same
  // publication rule the importer schedules against. Comparing the two is what
  // "healthy" means.
  string latest_verifiable_date = 2;

  // True when verified coverage has reached latest_verifiable_date. A
  // conversion whose publication date falls beyond coverage is refused, so
  // this answers "will posting work right now".
  bool healthy = 3;

  // Publication days between coverage and latest_verifiable_date. Zero when
  // healthy.
  int32 days_behind = 4;

  // True while a batch holds the single-running lock.
  bool import_running = 5;

  // When the scheduler next wakes, from the same cutoff the importer uses.
  string next_import_at = 6;

  // Newest first, running and failed attempts included.
  repeated EcbImportBatch batches = 7;

  // Distinct currencies observed on verified_through_date, so a coverage gap
  // for one currency is visible even when the date itself is covered.
  repeated string covered_currencies = 8;
}

// Conversion basis rule used to select an ECB publication.
enum EcbConversionContext {
  ECB_CONVERSION_CONTEXT_UNSPECIFIED = 0;
  ECB_CONVERSION_CONTEXT_ORDINARY_TRANSACTION = 1;
  ECB_CONVERSION_CONTEXT_FINANCIAL_STATEMENT = 2;
  ECB_CONVERSION_CONTEXT_DECISIVE_DATE = 3;
}

// Exact inputs for a conversion preview. Decimal values are strings so the
// client never loses precision through binary floating point.
message PreviewEcbConversionRequest {
  string original_amount = 1;
  string original_currency = 2;
  EcbConversionContext conversion_context = 3;

  // ISO calendar date (YYYY-MM-DD) from which the applicable publication date
  // is derived. Its meaning is selected by conversion_context: transaction,
  // statement, or decisive date.
  string conversion_basis_date = 4;

  // Required. Profile whose rates apply. Only consulted when use_custom_rate is
  // set, but always required so a preview names the books it describes.
  string profile_name = 5;

  // Preview the profile's own rate for the publication date rather than the ECB
  // reference rate. Must match what the posting will ask for, or the preview
  // describes a conversion that will not happen.
  bool use_custom_rate = 6;
}

// The conversion and immutable local ECB observation that would be used now.
// No rounding is performed and no conversion evidence is persisted.
message PreviewEcbConversionResponse {
  string original_amount = 1;
  string original_currency = 2;
  string eur_amount = 3;
  EcbConversionContext conversion_context = 4;
  string conversion_basis_date = 5;
  string determination_method = 6;
  string rounding_method = 7;
  optional string rate_date = 8;
  optional string units_per_eur = 9;
  optional int64 rate_observation_id = 10;
  optional string observation_hash = 11;
  optional string source_payload_hash = 12;
  optional string rate_fetched_at = 13;
  optional int64 import_batch_id = 14;
  optional string source_endpoint = 15;

  // Present only when determination_method is custom_rate. rate_date and
  // units_per_eur then describe the hand-entered row identified here, and the
  // ECB observation fields above are empty.
  optional int64 custom_rate_table_definition_id = 16;
  optional int64 custom_rate_record_id = 17;
  optional int64 custom_rate_row_revision = 18;
  optional string custom_rate_note = 19;
}

// Identify one logical money cell whose conversion history should be inspected.
message ListEcbConversionEvidenceRequest {
  // Required. Profile containing the table.
  string profile_name = 1;

  // Required. Logical table name within the profile.
  string table_name = 2;

  // Required. Dynamic table row id.
  int64 record_id = 3;

  // Required. Current display name of the money column. The server resolves it
  // to the stable physical column name used by immutable evidence.
  string column_name = 4;

  // Optional. Maximum rows to return. Zero uses 100; maximum is 500.
  int32 limit = 5;

  // Optional cursor. Return evidence ids lower than this value.
  optional int64 before_evidence_id = 6;
}

// One immutable explanation of how a posted EUR value was determined.
message EcbConversionEvidence {
  int64 evidence_id = 1;

  // Exact committed version of the target dynamic-table row.
  int64 row_revision = 2;
  string original_amount = 3;
  string original_currency = 4;
  string eur_amount = 5;
  string conversion_context = 6;
  string conversion_basis_date = 7;
  string determination_method = 8;
  string rounding_method = 9;
  optional string rate_date = 10;
  optional string units_per_eur = 11;
  optional int64 rate_observation_id = 12;
  optional string observation_hash = 13;
  optional string source_payload_hash = 14;
  optional string rate_fetched_at = 15;
  optional int64 import_batch_id = 16;
  optional string source_endpoint = 17;
  string evidence_created_at = 18;

  // Present only when determination_method is custom_rate. The hand-entered row
  // that supplied rate_date and units_per_eur. The row itself stays editable, so
  // the figures above are the immutable record of what was actually applied.
  optional int64 custom_rate_table_definition_id = 19;
  optional int64 custom_rate_record_id = 20;
  optional int64 custom_rate_row_revision = 21;
  optional string custom_rate_note = 22;
}

message ListEcbConversionEvidenceResponse {
  // True when at least one evidence row for this cell used a rate, whether it
  // came from ECB or from a hand-entered custom row.
  bool has_exchange = 1;

  // Newest-first immutable history for this page.
  repeated EcbConversionEvidence evidence = 2;

  // True when another page exists using the last evidence_id as the cursor.
  bool has_more = 3;
}