import type { SavedConnection, SavedQuery } from '../types';
import { t as translate } from '../i18n';
import { LEGACY_PERSIST_KEY } from './legacyConnectionStorage';

type StorageLike = Pick<Storage, 'getItem' | 'setItem'>;

export interface SavedQueryImportPayload {
  queries: SavedQuery[];
  legacyConnections?: SavedConnection[];
}

export interface SavedQueryBackend {
  GetSavedQueries?: () => Promise<SavedQuery[]>;
  SaveQuery?: (query: SavedQuery) => Promise<SavedQuery | null | undefined>;
  ImportSavedQueries?: (payload: SavedQueryImportPayload) => Promise<SavedQuery[]>;
  DeleteQuery?: (id: string) => Promise<void>;
  RebindSavedQuery?: (id: string, connectionId: string) => Promise<SavedQuery>;
}

export interface SavedQueryBootstrapArgs {
  backend?: SavedQueryBackend;
  replaceSavedQueries: (queries: SavedQuery[]) => void;
  storage?: StorageLike;
}

export interface SavedQueryBootstrapResult {
  importedLegacyCount: number;
  loadedCount: number;
}

let capturedLegacySavedQuerySource: SavedQueryImportPayload = { queries: [] };

const toTrimmedString = (value: unknown, fallback = ''): string => {
  if (typeof value === 'string') {
    return value.trim();
  }
  if (typeof value === 'number' || typeof value === 'boolean') {
    return String(value).trim();
  }
  return fallback;
};

const unwrapPersistedAppState = (payload: unknown): Record<string, unknown> => {
  if (!payload || typeof payload !== 'object') {
    return {};
  }
  const raw = payload as Record<string, unknown>;
  if (raw.state && typeof raw.state === 'object') {
    return raw.state as Record<string, unknown>;
  }
  return raw;
};

const resolveGeneratedSavedQueryName = (index: number): string => (
  translate('saved_query.default_name', { index: index + 1 })
);

const sanitizeSavedQuery = (value: unknown, index: number): SavedQuery | null => {
  if (!value || typeof value !== 'object') {
    return null;
  }
  const raw = value as Record<string, unknown>;
  const id = toTrimmedString(raw.id, `query-${index + 1}`) || `query-${index + 1}`;
  const sql = typeof raw.sql === 'string' ? raw.sql : toTrimmedString(raw.sql);
  const connectionId = toTrimmedString(raw.connectionId);
  const dbName = toTrimmedString(raw.dbName);
  if (!sql.trim() || !connectionId || !dbName) {
    return null;
  }
  const query: SavedQuery = {
    id,
    name: toTrimmedString(raw.name, resolveGeneratedSavedQueryName(index)) || resolveGeneratedSavedQueryName(index),
    sql,
    connectionId,
    dbName,
    createdAt: Number.isFinite(Number(raw.createdAt)) ? Number(raw.createdAt) : Date.now(),
  };
  const connectionFingerprint = toTrimmedString(raw.connectionFingerprint);
  const fingerprintVersion = toTrimmedString(raw.fingerprintVersion);
  const bindingStatus = toTrimmedString(raw.bindingStatus);
  const originalConnectionId = toTrimmedString(raw.originalConnectionId);
  if (connectionFingerprint) query.connectionFingerprint = connectionFingerprint;
  if (fingerprintVersion) query.fingerprintVersion = fingerprintVersion;
  if (bindingStatus) query.bindingStatus = bindingStatus;
  if (originalConnectionId) query.originalConnectionId = originalConnectionId;
  return query;
};

export const sanitizeSavedQueries = (value: unknown): SavedQuery[] => {
  if (!Array.isArray(value)) {
    return [];
  }
  const result: SavedQuery[] = [];
  const seen = new Set<string>();
  value.forEach((item, index) => {
    const query = sanitizeSavedQuery(item, index);
    if (!query || seen.has(query.id)) {
      return;
    }
    seen.add(query.id);
    result.push(query);
  });
  return result;
};

const mergeSavedQueriesById = (...groups: SavedQuery[][]): SavedQuery[] => {
  const result: SavedQuery[] = [];
  const indexById = new Map<string, number>();
  groups.flat().forEach((query) => {
    if (!query.id) {
      return;
    }
    const existingIndex = indexById.get(query.id);
    if (existingIndex === undefined) {
      indexById.set(query.id, result.length);
      result.push(query);
      return;
    }
    result[existingIndex] = query;
  });
  return result;
};

const sanitizeLegacyConnections = (value: unknown): SavedConnection[] => {
  if (!Array.isArray(value)) {
    return [];
  }
  return value.filter((item): item is SavedConnection => !!item && typeof item === 'object');
};

const mergeLegacyConnectionsById = (...groups: SavedConnection[][]): SavedConnection[] => {
  const result: SavedConnection[] = [];
  const indexById = new Map<string, number>();
  groups.flat().forEach((connection) => {
    const id = toTrimmedString((connection as { id?: unknown }).id);
    if (!id) {
      return;
    }
    const existingIndex = indexById.get(id);
    if (existingIndex === undefined) {
      indexById.set(id, result.length);
      result.push(connection);
      return;
    }
    result[existingIndex] = connection;
  });
  return result;
};

const mergeSavedQueryImportSources = (...sources: SavedQueryImportPayload[]): SavedQueryImportPayload => {
  return {
    queries: mergeSavedQueriesById(...sources.map((source) => source.queries || [])),
    legacyConnections: mergeLegacyConnectionsById(...sources.map((source) => source.legacyConnections || [])),
  };
};

export const captureLegacySavedQueriesSnapshot = (value: unknown, legacyConnections?: unknown): void => {
  const nextQueries = sanitizeSavedQueries(value);
  if (nextQueries.length === 0) {
    return;
  }
  capturedLegacySavedQuerySource = mergeSavedQueryImportSources(capturedLegacySavedQuerySource, {
    queries: nextQueries,
    legacyConnections: sanitizeLegacyConnections(legacyConnections),
  });
};

export const readLegacySavedQuerySourceFromPayload = (payload: string | null | undefined): SavedQueryImportPayload => {
  if (!payload || typeof payload !== 'string') {
    return { queries: [] };
  }
  try {
    const parsed = JSON.parse(payload) as Record<string, unknown>;
    const state = unwrapPersistedAppState(parsed);
    return {
      queries: sanitizeSavedQueries(state.savedQueries),
      legacyConnections: sanitizeLegacyConnections(state.connections),
    };
  } catch {
    return { queries: [] };
  }
};

export const readLegacySavedQueriesFromPayload = (payload: string | null | undefined): SavedQuery[] => (
  readLegacySavedQuerySourceFromPayload(payload).queries
);

export const stripLegacySavedQueries = (payload: string | null | undefined): string => {
  if (!payload || typeof payload !== 'string') {
    return '';
  }
  try {
    const parsed = JSON.parse(payload) as Record<string, unknown>;
    const state = unwrapPersistedAppState(parsed);
    if (state.savedQueries === undefined) {
      return payload;
    }
    delete state.savedQueries;
    return JSON.stringify(parsed);
  } catch {
    return payload;
  }
};

const resolveStorage = (storage?: StorageLike): StorageLike | undefined => {
  if (storage) {
    return storage;
  }
  if (typeof window === 'undefined') {
    return undefined;
  }
  return window.localStorage;
};

const readLegacySavedQuerySourceFromStorage = (storage?: StorageLike): SavedQueryImportPayload => {
  const rawPayload = storage?.getItem(LEGACY_PERSIST_KEY) ?? null;
  return readLegacySavedQuerySourceFromPayload(rawPayload);
};

const cleanupLegacySavedQueriesFromStorage = (storage?: StorageLike): void => {
  const rawPayload = storage?.getItem(LEGACY_PERSIST_KEY) ?? null;
  const sanitizedPayload = stripLegacySavedQueries(rawPayload);
  if (sanitizedPayload && sanitizedPayload !== rawPayload) {
    storage?.setItem(LEGACY_PERSIST_KEY, sanitizedPayload);
  }
};

export const saveSavedQueryToBackend = async (
  backend: SavedQueryBackend | undefined,
  query: SavedQuery,
): Promise<SavedQuery> => {
  const sanitized = sanitizeSavedQuery(query, 0);
  if (!sanitized) {
    throw new Error(translate('saved_query.error.missing_context'));
  }
  if (typeof backend?.SaveQuery !== 'function') {
    return sanitized;
  }
  const saved = await backend.SaveQuery(sanitized);
  return sanitizeSavedQuery(saved || sanitized, 0) || sanitized;
};

export const deleteSavedQueryFromBackend = async (
  backend: SavedQueryBackend | undefined,
  id: string,
): Promise<void> => {
  if (typeof backend?.DeleteQuery === 'function') {
    await backend.DeleteQuery(id);
  }
};

export async function bootstrapSavedQueries(args: SavedQueryBootstrapArgs): Promise<SavedQueryBootstrapResult> {
  const storage = resolveStorage(args.storage);
  const storageLegacySource = readLegacySavedQuerySourceFromStorage(storage);
  const legacySource = mergeSavedQueryImportSources(capturedLegacySavedQuerySource, storageLegacySource);
  const legacyQueries = legacySource.queries;
  let importedLegacyCount = 0;

  if (legacyQueries.length > 0) {
    if (typeof args.backend?.ImportSavedQueries === 'function') {
      await args.backend.ImportSavedQueries(legacySource);
      importedLegacyCount = legacyQueries.length;
      capturedLegacySavedQuerySource = { queries: [] };
      cleanupLegacySavedQueriesFromStorage(storage);
    } else if (typeof args.backend?.SaveQuery === 'function') {
      for (const query of legacyQueries) {
        await args.backend.SaveQuery(query);
      }
      importedLegacyCount = legacyQueries.length;
      capturedLegacySavedQuerySource = { queries: [] };
      cleanupLegacySavedQueriesFromStorage(storage);
    }
  }

  let loadedQueries: SavedQuery[] = [];
  if (typeof args.backend?.GetSavedQueries === 'function') {
    loadedQueries = sanitizeSavedQueries(await args.backend.GetSavedQueries());
  }
  if (loadedQueries.length === 0 && importedLegacyCount === 0 && legacyQueries.length > 0) {
    loadedQueries = legacyQueries;
  }
  args.replaceSavedQueries(loadedQueries);

  return {
    importedLegacyCount,
    loadedCount: loadedQueries.length,
  };
}