import type {
  UnifiedResultProjection,
  UnifiedResultQuery,
  UnifiedResultQueryResult
} from '../domain/unified-result';

export const RESULT_DB_JSONL_FORMAT = 'assessor-result-db-jsonl';
export const RESULT_DB_JSONL_SCHEMA_VERSION = '1.0.0';
export const RESULT_DB_EXPORT_PAGE_SIZE = 1000;

type ResultPageReader = (query: UnifiedResultQuery) => Promise<UnifiedResultQueryResult>;

function definedQueryEntries(query: UnifiedResultQuery): Array<[string, unknown]> {
  return Object.entries(query).filter(([, value]) => value !== undefined);
}

function exportScope(query: UnifiedResultQuery): Record<string, unknown> {
  const scopeKeys = new Set(['projectId', 'assessmentId', 'scanRunId', 'scanRunIds', 'evaluationRunId']);
  return Object.fromEntries(definedQueryEntries(query).filter(([key]) => scopeKeys.has(key)));
}

function exportFilters(query: UnifiedResultQuery): Record<string, unknown> {
  const excluded = new Set(['projectId', 'assessmentId', 'scanRunId', 'scanRunIds', 'evaluationRunId', 'offset', 'limit']);
  return Object.fromEntries(definedQueryEntries(query).filter(([key]) => !excluded.has(key)));
}

export function buildUnifiedResultJsonl(
  query: UnifiedResultQuery,
  results: UnifiedResultProjection[],
  generatedAt: string
): string {
  const lines = [{
    recordType: 'manifest',
    format: RESULT_DB_JSONL_FORMAT,
    schemaVersion: RESULT_DB_JSONL_SCHEMA_VERSION,
    generatedAt,
    resultCount: results.length,
    scope: exportScope(query),
    filters: exportFilters(query)
  }, ...results.map((result, index) => ({
    recordType: 'result',
    position: index + 1,
    result
  }))];
  return `${lines.map(line => JSON.stringify(line)).join('\n')}\n`;
}

export function unifiedResultJsonlFileName(generatedAt: string): string {
  const timestamp = generatedAt.replace(/\.\d{3}Z$/, 'Z').replaceAll(':', '-');
  return `assessor-result-db-filtered-${timestamp}.jsonl`;
}

export async function queryAllUnifiedResults(
  readPage: ResultPageReader,
  query: UnifiedResultQuery,
  pageSize = RESULT_DB_EXPORT_PAGE_SIZE
): Promise<UnifiedResultProjection[]> {
  const baseQuery = { ...query, offset: undefined, limit: undefined };
  const results: UnifiedResultProjection[] = [];
  let expectedTotal: number | undefined;

  while (expectedTotal === undefined || results.length < expectedTotal) {
    const page = await readPage({ ...baseQuery, offset: results.length, limit: pageSize });
    if (expectedTotal === undefined) expectedTotal = page.total;
    if (page.total !== expectedTotal) throw new Error('The filtered result set changed during export. Please retry.');
    if (!page.items.length && results.length < expectedTotal) throw new Error('The filtered result export ended before all rows were returned.');
    results.push(...page.items);
  }

  if (results.length !== expectedTotal) throw new Error('The filtered result export returned an inconsistent row count.');
  return results;
}