// common/proto/table_script.proto
syntax = "proto3";
package komp_ac.table_script;

// Manages column-computation scripts for user-defined tables and supplies the
// dependency data used by the client-side Steel runtime.
// Each script belongs to a single table (table_definition_id) and populates
// exactly one target column in that table. The server:
// - Validates script syntax (non-empty, balanced parentheses, starts with '(')
// - Validates the target column (exists, not a system column, allowed type)
// - Validates column/type usage inside math expressions
// - Validates referenced tables/columns against the schema
// - Enforces link constraints for structured access (see notes below)
// - Analyzes dependencies and prevents cycles across the schema
// - Transforms the script to decimal-safe math (steel_decimal)
// - Upserts into table_scripts and records dependencies in script_dependencies
// - Hydrates external column and aggregate inputs requested by the client
//
// The client fetches stored scripts and their declared dependencies, builds a
// restricted Steel context, and executes scripts for immediate form feedback.
// Current-table values come from the client's active row snapshot. External
// values must come from HydrateScriptDependencies; the client must not query
// arbitrary database data from inside the Steel VM.
//
// Server-side persistence remains authoritative and recalculates affected rows.
// Script creation and update are transactional.
service TableScript {
  // Create or update a script for a specific table and target column.
  //
  // Behavior:
  // - Fetches the table by table_definition_id (must exist)
  // - Validates "script" (syntax), "target_column" (exists and type rules),
  //   and all referenced tables/columns (must exist in same schema)
  // - Validates math operations: prohibits using certain data types in math
  // - Enforces link constraints for structured table access:
  //    • Allowed always: self-references (same table)
  //    • Structured access via steel_get_column
  //      requires an explicit link in table_definition_links
  // - Rejects raw SQL access; steel_query_sql is not part of the supported DSL
  // - Detects and rejects circular dependencies across all scripts in the schema
  //   (self-references are allowed and not treated as cycles)
  // - Transforms the script to decimal-safe operations (steel_decimal)
  // - UPSERTS into table_scripts on (table_definitions_id, target_column)
  //   and saves a normalized dependency list into script_dependencies
  rpc PostTableScript(PostTableScriptRequest) returns (TableScriptResponse);

  // Fetch all stored scripts for a specific table.
  //
  // Behavior:
  // - Resolves the table from (profile_name, table_name)
  // - Returns the stored, transformed script from table_scripts
  // - Includes normalized dependency metadata from script_dependencies
  // - Returns an empty scripts list when the table has no scripts
  //
  // Client use:
  // - Registers each client-evaluable script with the computed-field runtime
  // - Uses dependencies as the allowlist for values exposed to the Steel VM
  // - Uses target_column_type to validate and convert the script result
  rpc GetTableScripts(GetTableScriptsRequest) returns (GetTableScriptsResponse);

  // Build the external data snapshot needed to execute a table's scripts in
  // the client-side Steel runtime.
  //
  // The server derives the required inputs from stored script_dependencies;
  // callers do not choose arbitrary tables or columns. Direct related-column
  // reads and related aggregates are evaluated through SQLx in one read-only
  // PostgreSQL snapshot. Returned values include logical type and currency
  // metadata so the client can create correctly typed ScriptValues.
  //
  // Current-table column values are intentionally not returned. The client
  // supplies those directly from row_data so unsaved edits participate in
  // immediate calculations. The response replaces the client's previous
  // script dependency cache as one complete hydration snapshot.
  rpc HydrateScriptDependencies(HydrateScriptDependenciesRequest)
      returns (HydrateScriptDependenciesResponse);
}

// Request to create or update a script bound to a specific table and column.
message PostTableScriptRequest {
  // Required. The metadata ID from table_definitions.id that identifies the
  // table this script belongs to. The table must exist; its schema determines
  // where referenced tables/columns are validated and where dependencies are stored.
  int64 table_definition_id = 1;

  // Required. The target column in the target table that this script computes.
  // Must be an existing user-defined column in that table (not a system column).
  // System columns are reserved: "id", "deleted", "created_at", "row_revision".
  // The column's data type must NOT be one of the prohibited target types:
  //   BIGINT, DATE, TIMESTAMPTZ
  // Note: BOOLEAN targets are allowed (values are converted to Steel #true/#false).
  string target_column = 2;

  // Required. The script in the Steel DSL (S-expression style).
  // Syntax requirements:
  //   - Non-empty, must start with '('
  //   - Balanced parentheses
  //
  // Referencing data:
  //   - Structured table/column access (enforces link constraints):
  //       (steel_get_column "table_name" "column_name")
  //       • current-table references are read directly from the active row
  //       • other tables require an explicit link from the source table
  //         (table_definition_links) or the request fails
  //   - Related collections use allowlisted aggregate shorthand:
  //       @sum(table.column), @min(table.column), @max(table.column),
  //       @count(table.column), @count_distinct(table.column),
  //       @any(table.boolean), @all(table.boolean),
  //       @count_rows(table via anchor), @exists(table via anchor)
  //       Every related aggregate requires the `via anchor` clause. The related
  //       table must be reachable through that anchor by an unambiguous FK path;
  //       the path may span multiple FK hops.
  //   - Raw SQL access is not supported; steel_query_sql is rejected
  //
  // Math operations:
  //   - The script is transformed by steel_decimal; supported math forms include:
  //     +, -, *, /, ^, **, pow, sqrt, >, <, =, >=, <=, min, max, abs, round,
  //     ln, log, log10, exp, sin, cos, tan
  //   - Columns of the following types CANNOT be used inside math expressions:
  //     BIGINT, TEXT, BOOLEAN, DATE, TIMESTAMPTZ
  //
  // Dependency tracking and cycles:
  //   - Dependencies are extracted from steel_get_column calls and stored
  //     in script_dependencies with context
  //   - Cycles across tables are rejected (self-dependency is allowed)
  string script = 3;

  // Optional. Free-text description stored alongside the script (no functional effect).
  string description = 4;

}

// Response after creating or updating a script.
message TableScriptResponse {
  // The ID of the script record in table_scripts (new or existing on upsert).
  int64 id = 1;

  // Human-readable warnings concatenated into a single string. Possible messages:
  //  - Warning if the script references itself (may affect first population)
  //  - Info about number of structured linked-table accesses
  //  - Warning if many dependencies may affect performance
  string warnings = 2;
}

message GetTableScriptsRequest {
  // Required. Profile (schema) name.
  string profile_name = 1;

  // Required. Table name within the profile.
  string table_name = 2;
}

message GetTableScriptsResponse {
  // Scripts and dependency allowlists used to configure the client Steel runtime.
  repeated StoredTableScript scripts = 1;
}

message StoredTableScript {
  // Persistent script identifier.
  int64 id = 1;
  // Display-name key of the current-table field populated by this script.
  string target_column = 2;
  // Logical type used by the client to validate and convert the result.
  string target_column_type = 3;
  // Validated and transformed Steel expression executed by the client for
  // immediate feedback and by the server for authoritative persistence.
  string script = 4;
  string description = 5;
  // Complete allowlist of data inputs that may be exposed to this script.
  repeated ScriptDependency dependencies = 6;
}

message ScriptDependency {
  // Logical table name referenced by the script.
  string target_table = 1;
  // Normalized dependency kind, such as column_access or related_aggregate.
  string dependency_type = 2;
  // Logical column name. Empty for aggregates that operate on rows only.
  string column = 3;
  // Aggregate operation name, such as sum, count_rows, or exists; empty for
  // column_access dependencies.
  string operation = 4;
  // Relationship table used to match the owner row to the related collection.
  string via_table = 5;
}

// Identifies the active form row whose external Steel inputs must be hydrated.
message HydrateScriptDependenciesRequest {
  // Required profile/database schema containing the scripted table.
  string profile_name = 1;
  // Required logical name of the table owning the scripts.
  string table_name = 2;
  // Persisted owner-row ID, or zero for a new unsaved row.
  int64 row_id = 3;
  // Complete current client form snapshot keyed by logical column name.
  // It contains unsaved current-table values and related foreign keys such as
  // "customer_id". The server uses it to resolve related rows and new-row
  // aggregate semantics; it is not an arbitrary dependency request.
  map<string, string> row_data = 4;
}

// One declared cross-table column input for the client Steel context.
message HydratedColumnValue {
  // Logical related-table name used by steel_get_column.
  string target_table = 1;
  // Related row from which the value was loaded.
  int64 row_id = 2;
  // Logical column name used by steel_get_column.
  string column = 3;
  // String-encoded database value. An empty string represents NULL/empty input.
  string value = 4;
  // Logical database type used to create a typed client ScriptValue.
  string field_type = 5;
  // Related table's base currency for MONEY values; otherwise empty.
  string base_currency = 6;
}

// One declared related-collection aggregate input for the client Steel context.
message HydratedAggregateValue {
  // Normalized aggregate operation: sum, min, max, count, count_distinct,
  // any, all, count_rows, or exists.
  string operation = 1;
  // Logical table whose related rows were aggregated.
  string target_table = 2;
  // Logical aggregated column; empty for count_rows and exists.
  string column = 3;
  // Relationship anchor used to distinguish aggregate dependency paths.
  string via_table = 4;
  // String-encoded aggregate result.
  string value = 5;
  // Logical source-column type; empty for row-only aggregates.
  string field_type = 6;
  // Aggregate table's base currency for MONEY values; otherwise empty.
  string base_currency = 7;
}

// Complete external dependency snapshot for client-side Steel execution.
message HydrateScriptDependenciesResponse {
  // Exact related-column inputs declared by stored scripts.
  repeated HydratedColumnValue columns = 1;
  // Exact related aggregate inputs declared by stored scripts.
  repeated HydratedAggregateValue aggregates = 2;
}