import type { CorpusDataset } from '../types/corpus';

const STORAGE_KEY_CUSTOM_DATASETS = 'castorini_ir_custom_datasets';
const STORAGE_KEY_ACTIVE_DATASET = 'castorini_ir_active_dataset_id';

export function loadStoredCustomDatasets(): CorpusDataset[] {
  if (typeof window === 'undefined' || !window.localStorage) {
    return [];
  }
  try {
    const raw = window.localStorage.getItem(STORAGE_KEY_CUSTOM_DATASETS);
    if (!raw) return [];
    const parsed = JSON.parse(raw);
    if (Array.isArray(parsed)) {
      return parsed;
    }
  } catch (err) {
    console.error('Failed to load custom datasets from storage:', err);
  }
  return [];
}

export function saveStoredCustomDataset(dataset: CorpusDataset): boolean {
  if (typeof window === 'undefined' || !window.localStorage) {
    return false;
  }
  try {
    const existing = loadStoredCustomDatasets();
    const index = existing.findIndex((d) => d.id === dataset.id);
    if (index >= 0) {
      existing[index] = dataset;
    } else {
      existing.unshift(dataset);
    }
    window.localStorage.setItem(STORAGE_KEY_CUSTOM_DATASETS, JSON.stringify(existing));
    return true;
  } catch (err) {
    console.error('Failed to save custom dataset to storage:', err);
    return false;
  }
}

export function deleteStoredCustomDataset(datasetId: string): boolean {
  if (typeof window === 'undefined' || !window.localStorage) {
    return false;
  }
  try {
    const existing = loadStoredCustomDatasets();
    const filtered = existing.filter((d) => d.id !== datasetId);
    window.localStorage.setItem(STORAGE_KEY_CUSTOM_DATASETS, JSON.stringify(filtered));
    return true;
  } catch (err) {
    console.error('Failed to delete custom dataset from storage:', err);
    return false;
  }
}

export function getStoredActiveDatasetId(): string {
  if (typeof window === 'undefined' || !window.localStorage) {
    return 'msmarco-subset';
  }
  try {
    const active = window.localStorage.getItem(STORAGE_KEY_ACTIVE_DATASET);
    return active || 'msmarco-subset';
  } catch {
    return 'msmarco-subset';
  }
}

export function setStoredActiveDatasetId(id: string): void {
  if (typeof window === 'undefined' || !window.localStorage) {
    return;
  }
  try {
    window.localStorage.setItem(STORAGE_KEY_ACTIVE_DATASET, id);
  } catch (err) {
    console.error('Failed to save active dataset id:', err);
  }
}