import Hashids from 'hashids';
import { useQuery } from '@tanstack/react-query';

const env = (typeof import.meta !== 'undefined' && import.meta.env
  ? import.meta.env
  : {}) as Record<string, string | undefined>;

/**
 * Deterministic Hashids configuration matching pfm-api HasherSettings.
 * Ensures 100% interoperability with the C# Hashids.net NuGet package on the backend.
 */
export const HASHER_SETTINGS = {
  minHashLength: Number(env.VITE_HASHER_MIN_LENGTH) || 11,
  salt:
    (env.VITE_HASHER_SALT as string) ||
    'TGlnaHQgQ2hhcm1zLCBNaWRyYW5kQm9va3MgbWFrZSBsb3RzIG9mIG1vbmV5IGFuZCBhcmUgYSBzdWNjZXNzZnVsIHZpcmFsIHN0b3J5IGluIFNvdXRoIEFmcmljYQ==',
};

let hasher = new Hashids(HASHER_SETTINGS.salt, HASHER_SETTINGS.minHashLength);

export function updateHasherSettings(salt?: string, minLength?: number | string): void {
  let updated = false;
  if (salt && typeof salt === 'string' && salt.trim() !== '') {
    HASHER_SETTINGS.salt = salt.trim();
    updated = true;
  }
  if (minLength !== undefined && minLength !== null && minLength !== '') {
    const parsed = Number(minLength);
    if (!isNaN(parsed) && parsed > 0) {
      HASHER_SETTINGS.minHashLength = parsed;
      updated = true;
    }
  }
  if (updated) {
    hasher = new Hashids(HASHER_SETTINGS.salt, HASHER_SETTINGS.minHashLength);
  }
}

export function isAlreadyHashId(candidate: string): boolean {
  if (
    typeof candidate !== 'string' ||
    candidate.length < HASHER_SETTINGS.minHashLength ||
    /^\d+$/.test(candidate)
  ) {
    return false;
  }
  try {
    const decoded = hasher.decode(candidate);
    if (!Array.isArray(decoded) || decoded.length === 0) {
      return false;
    }
    return hasher.encode(decoded as number[]) === candidate;
  } catch {
    return false;
  }
}

export function encodeHashIdSync(id: number | string | null | undefined): string {
  if (id === undefined || id === null || id === '') {
    return '';
  }

  if (typeof id === 'number') {
    if (isNaN(id) || !isFinite(id) || id < 0) return '';
    return hasher.encode(id);
  }

  const str = String(id).trim();
  if (!str) return '';

  if (isAlreadyHashId(str)) {
    return str;
  }

  if (/^\d+$/.test(str)) {
    try {
      const num = parseInt(str, 10);
      if (!isNaN(num) && num >= 0) {
        return hasher.encode(num);
      }
    } catch {
      // Fall through
    }
  }

  return str;
}

export function decodeHashIdSync(hashId: string | number | null | undefined): number | string {
  if (hashId === undefined || hashId === null || hashId === '') return '';
  if (typeof hashId === 'number') return hashId;

  const str = String(hashId).trim();
  if (!str) return '';

  if (/^-?\d+$/.test(str)) {
    const parsed = parseInt(str, 10);
    return isNaN(parsed) ? str : parsed;
  }

  try {
    const decoded = hasher.decode(str);
    if (Array.isArray(decoded) && decoded.length > 0) {
      return Number(decoded[0]);
    }
  } catch {
    // If decoding fails, return raw string
  }

  return str;
}

export function decodeToNumberSync(hashId: number | string | null | undefined): number {
  if (hashId === null || hashId === undefined || hashId === '') return 0;
  if (typeof hashId === 'number') {
    return isNaN(hashId) ? 0 : Math.trunc(hashId);
  }
  const str = String(hashId).trim();
  if (/^-?\d+$/.test(str)) {
    const parsed = parseInt(str, 10);
    return isNaN(parsed) ? 0 : parsed;
  }
  try {
    const decoded = hasher.decode(str);
    if (Array.isArray(decoded) && decoded.length > 0) {
      return Number(decoded[0]);
    }
  } catch {}
  const fallback = Number(str);
  return isNaN(fallback) ? 0 : Math.trunc(fallback);
}

export const toolsService = {
  encodeIdSync(id: number | string | null | undefined): string {
    return encodeHashIdSync(id);
  },

  decodeIdSync(hashId: string | number | null | undefined): number | string {
    return decodeHashIdSync(hashId);
  },

  decodeToNumberSync(hashId: number | string | null | undefined): number {
    return decodeToNumberSync(hashId);
  },

  async encodeId(id: number | string | null | undefined, _context = 'general'): Promise<string> {
    return encodeHashIdSync(id);
  },

  async decodeId(hashId: string | null | undefined, _context = 'general'): Promise<number | string> {
    return decodeHashIdSync(hashId);
  },

  async resolveProjectId(projectId: number | string): Promise<string> {
    return encodeHashIdSync(projectId);
  },

  async resolveOrganisationId(organisationId: number | string): Promise<string> {
    return encodeHashIdSync(organisationId);
  },

  async resolveProgrammeId(programmeId: number | string): Promise<string> {
    return encodeHashIdSync(programmeId);
  },

  async resolvePortfolioId(portfolioId: number | string): Promise<string> {
    return encodeHashIdSync(portfolioId);
  },

  async resolveAwardId(awardId: number | string): Promise<string> {
    return encodeHashIdSync(awardId);
  },

  async resolveContractId(contractId: number | string): Promise<string> {
    return encodeHashIdSync(contractId);
  },

  async resolveActivityId(activityId: number | string): Promise<string> {
    return encodeHashIdSync(activityId);
  },

  async resolveMilestoneId(milestoneId: number | string): Promise<string> {
    return encodeHashIdSync(milestoneId);
  },

  async resolveHashedParams<T extends Record<string, any>>(
    params: T,
    keysToHash: (keyof T)[]
  ): Promise<T> {
    const resolved: any = { ...params };
    for (const key of keysToHash) {
      const val = params[key];
      if (val !== undefined && val !== null) {
        resolved[key] = encodeHashIdSync(val);
      }
    }
    return resolved;
  },

  async primeCache(_items: { id: number | string; context: string }[]): Promise<void> {
    // No-op - instant deterministic computation
  },
};

export function useHashId(id?: number | string | null, context = 'general') {
  return useQuery({
    queryKey: ['hashId', context, id !== undefined && id !== null ? String(id) : ''],
    queryFn: () => Promise.resolve(encodeHashIdSync(id)),
    enabled: id !== undefined && id !== null && id !== '',
    staleTime: Infinity,
  });
}