syntax = "proto3";

package komp_ac.ecb;

// How the publication date is selected from the accounting basis date.
enum ExchangeRateDateRule {
  EXCHANGE_RATE_DATE_RULE_UNSPECIFIED = 0;
  // Latest TARGET publication strictly before the basis date.
  EXCHANGE_RATE_DATE_RULE_PREVIOUS_PUBLICATION = 1;
  // Latest TARGET publication on or before the basis date.
  EXCHANGE_RATE_DATE_RULE_ON_OR_BEFORE_DATE = 2;
  // The exact publication date supplied in specific_rate_date.
  EXCHANGE_RATE_DATE_RULE_SPECIFIC_PUBLICATION_DATE = 3;
}

enum ExchangeRateSource {
  EXCHANGE_RATE_SOURCE_UNSPECIFIED = 0;
  // The rate source's own published reference rate (ECB's, today).
  EXCHANGE_RATE_SOURCE_OFFICIAL = 1;
  // A reusable rate from the profile's custom_exchange_rates table.
  EXCHANGE_RATE_SOURCE_SAVED_CUSTOM = 2;
  // A one-off rate recorded only in this posting's immutable evidence.
  EXCHANGE_RATE_SOURCE_MANUAL = 3;
}

// Accountant-controlled conversion treatment. Exceptional choices remain
// explicit and auditable rather than being inferred from a legal label.
message ExchangeRateSelection {
  ExchangeRateDateRule date_rule = 1;
  ExchangeRateSource source = 2;
  // Required for SPECIFIC_PUBLICATION_DATE and MANUAL; YYYY-MM-DD.
  optional string specific_rate_date = 3;
  // Required only for MANUAL. Exact foreign-currency units per one unit of
  // the rate source's pivot currency (EUR for ECB).
  optional string manual_units_per_pivot = 4;
  // Required for SPECIFIC_PUBLICATION_DATE and MANUAL.
  string reason = 5;
}

// 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;

  // Current coverage restated as the question a reader actually has: what may
  // be posted right now. Both are the latest basis date whose derived
  // publication date is still covered, under the two rules
  // required_publication_date applies -- transactions look strictly before the
  // basis date, statements and decisive dates look at it directly, so the
  // transaction bound is the later of the two. Derived here rather than by the
  // caller so it cannot disagree with the calendar the conversion path uses.
  // Absent when nothing has ever been verified and nothing can be posted.
  optional string transactions_postable_through = 9;
  optional string statements_postable_through = 10;
}

// 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;

  // ISO calendar date (YYYY-MM-DD) of the accounting case.
  string conversion_basis_date = 3;

  // Required. Profile whose rates apply. Consulted when the selection requests
  // a saved custom rate, and always required so the preview names its books.
  string profile_name = 4;

  // Empty uses previous publication and ECB.
  optional ExchangeRateSelection exchange_rate_selection = 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 converted_amount = 3;
  string conversion_basis_date = 4;
  string determination_method = 5;
  string rounding_method = 6;
  optional string rate_date = 7;
  optional string units_per_pivot = 8;
  optional int64 rate_observation_id = 9;
  optional string observation_hash = 10;
  optional string source_payload_hash = 11;
  optional string rate_fetched_at = 12;
  optional int64 import_batch_id = 13;
  optional string source_endpoint = 14;

  // Present only when determination_method is custom_rate. rate_date and
  // units_per_pivot then describe the hand-entered row identified here, and
  // the ECB observation fields above are empty.
  optional int64 custom_rate_table_definition_id = 15;
  optional int64 custom_rate_record_id = 16;
  optional int64 custom_rate_row_revision = 17;
  optional string custom_rate_note = 18;

  // Accountant-supplied justification for an exceptional publication date or
  // one-off manual rate. Empty for the normal/default rule.
  ExchangeRateDateRule applied_date_rule = 19;
  ExchangeRateSource applied_source = 20;
  string selection_reason = 21;

  // The currency converted_amount is stated in: the profile's accounting
  // currency (EUR unless the profile keeps its books in something else).
  string converted_currency = 22;

  // True when reaching converted_currency needed two hops (original currency
  // to EUR, then EUR to converted_currency) because neither is EUR. The
  // fields above then describe only the second, final hop; the full
  // provenance of both hops is available from ListEcbConversionEvidence
  // after posting.
  bool via_two_hop_conversion = 23;
}

// 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 converted_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_pivot = 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_pivot. 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;

  // Immutable audit data for an accountant-controlled exception.
  string selection_reason = 23;
  optional string selected_by_user_id = 24;

  // The currency converted_amount is stated in. Always EUR for the
  // original-currency-to-EUR leg; the profile's native currency for the
  // EUR-to-native leg that follows it when that native currency is not EUR.
  string converted_currency = 25;

  // Set only on the EUR-to-native-currency leg of a two-hop conversion. Names
  // the original-currency-to-EUR leg's evidence_id, which produced this row's
  // original_amount/original_currency (always EUR).
  optional int64 derived_from_evidence_id = 26;

  // The pivot currency of the rate source that priced this hop (EUR for
  // every hop today). A rate-based hop always has this currency on exactly
  // one side of original_currency/converted_currency.
  string pivot_currency = 27;

  // Which rate source's policy governs this hop's profile ("ecb" for every
  // hop today). Absent only for already_same_currency, where no policy
  // needed to be consulted. This is about which policy applies, not about
  // who actually supplied this specific rate -- see observation_source_id
  // for that.
  optional string policy_source_id = 28;

  // Which rate source actually supplied this hop's rate as its own official
  // observation. Present only when determination_method is
  // official_reference_rate; absent for custom_rate, manual_rate, and
  // already_same_currency, since none of those were priced by the policy's
  // source itself -- a human entered them.
  optional string observation_source_id = 29;
}

message ListEcbConversionEvidenceResponse {
  // True when at least one evidence row for this cell used an ECB, saved
  // custom, or one-off manual rate.
  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;
}