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);
}

// Accounting date 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). Its meaning is selected by
  // conversion_context: transaction, statement, or decisive date.
  string anchor_date = 4;

  // Required. Profile whose custom exchange rate table is consulted before the
  // ECB observations, so the preview matches what posting into that profile
  // would do.
  string profile_name = 5;
}

// 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 anchor_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 anchor_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;
}