import { snapshotOrgChartDataset } from './snapshot.js';
import type { OrgChartDataSource } from './types.js';

export type OrgChartSourceErrorCode = 'SOURCE_LOAD' | 'SOURCE_PARSE' | 'SOURCE_ABORT' | 'SOURCE_URL' | 'SOURCE_SNAPSHOT';
export class OrgChartSourceError extends Error {
  readonly path = 'dataSource';
  constructor(readonly code: OrgChartSourceErrorCode, message: string) {
    super(message);
    this.name = 'OrgChartSourceError';
  }
}
export interface JsonOrgChartDataSourceOptions { fetch?: typeof globalThis.fetch }
/** Inline JSON is captured at construction; URL sources load a fresh snapshot on each call. */
export class JsonOrgChartDataSource implements OrgChartDataSource {
  private readonly inline: unknown;
  private readonly url: string | undefined;
  private readonly fetcher: typeof globalThis.fetch | undefined;
  constructor(input: unknown, options: JsonOrgChartDataSourceOptions = {}) {
    // Browser-native fetch may require the global Window receiver. Retaining it as
    // an instance property must not accidentally call it with this source as `this`.
    this.fetcher = options.fetch ?? globalThis.fetch?.bind(globalThis);
    if (typeof input === 'string' || input instanceof URL) {
      const url = String(input);
      if (!safeSourceUrl(url)) throw new OrgChartSourceError('SOURCE_URL', 'Data source URL must use HTTP(S) or a relative JSON path.');
      this.url = url;
    } else {
      try { this.inline = snapshotOrgChartDataset(input); }
      catch { throw new OrgChartSourceError('SOURCE_SNAPSHOT', 'Data source input must be cloneable JSON.'); }
    }
  }
  async load(options: { signal?: AbortSignal } = {}): Promise<unknown> {
    const signal = options.signal;
    const aborted = () => { if (signal?.aborted) throw new OrgChartSourceError('SOURCE_ABORT', 'Data source request was cancelled.'); };
    aborted();
    if (this.url === undefined) return snapshotOrgChartDataset(this.inline);
    if (!this.fetcher) throw new OrgChartSourceError('SOURCE_LOAD', 'No fetch implementation is available.');
    let response: Response;
    try { response = await this.fetcher(this.url, { signal }); }
    catch {
      aborted();
      throw new OrgChartSourceError('SOURCE_LOAD', 'Data source could not be loaded.');
    }
    aborted();
    if (!response.ok) throw new OrgChartSourceError('SOURCE_LOAD', 'Data source returned an unsuccessful response.');
    let payload: unknown;
    try { payload = await response.json(); }
    catch {
      aborted();
      throw new OrgChartSourceError('SOURCE_PARSE', 'Data source response is not valid JSON.');
    }
    aborted();
    try { return snapshotOrgChartDataset(payload); }
    catch { throw new OrgChartSourceError('SOURCE_SNAPSHOT', 'Data source response must be cloneable JSON.'); }
  }
}
function safeSourceUrl(value: string): boolean {
  if (!value.trim() || /[\s\\<>\u0000-\u001f\u007f-\u009f\u202a-\u202e\u2066-\u2069]/.test(value) || value.startsWith('//')) return false;
  if (!/^[a-z][a-z\d+.-]*:/i.test(value)) return !/%(?:0[0-9a-f]|1[0-9a-f]|7f|5c)/i.test(value);
  try { const parsed = new URL(value); return ['http:', 'https:'].includes(parsed.protocol) && !parsed.username && !parsed.password; }
  catch { return false; }
}