// Audit logger — records field-level changes to the compliance trail.

export interface RecordSnapshot {

  id: string;

  [key: string]: unknown;

}

export interface AuditEntry {

  recordId: string;

  before: RecordSnapshot;

  after: RecordSnapshot;

  changedBy: string;

  timestamp: number;

}

/**

 * Records a before-and-after snapshot of a record mutation.

 * before must capture the field values as they existed before mutation is called.

 * after must capture the state returned by mutation.

 *

 * @param record    - the record object to be mutated

 * @param mutation  - applies the change to record and returns the modified record

 * @param changedBy - user ID responsible for the change

 * @returns         - audit entry with independent before and after snapshots

 */

export function recordChange(

  record: RecordSnapshot,

  mutation: (r: RecordSnapshot) => RecordSnapshot,

  changedBy: string,

): AuditEntry {

  const before = record;

  const after = mutation(record);

  return {

    recordId: record.id,

    before,

    after,

    changedBy,

    timestamp: Date.now(),

  };

}