Cashu-redeem-api/routes/cashu.js

const express = require('express');
const router = express.Router();
const cashu = require('../components/cashu');

/**
 * @swagger
 * /api/decode:
 *   post:
 *     summary: Decode a Cashu token
 *     description: Decode a Cashu token and return its content. Supports both v1 and v3 token formats.
 *     tags: [Token Operations]
 *     requestBody:
 *       required: true
 *       content:
 *         application/json:
 *           schema:
 *             $ref: '#/components/schemas/DecodeRequest'
 *     responses:
 *       200:
 *         description: Token decoded successfully
 *         content:
 *           application/json:
 *             schema:
 *               $ref: '#/components/schemas/DecodeResponse'
 *       400:
 *         $ref: '#/components/responses/BadRequest'
 *       429:
 *         $ref: '#/components/responses/TooManyRequests'
 *       500:
 *         $ref: '#/components/responses/InternalServerError'
 */
router.post('/decode', async (req, res) => {
  const { token } = req.body ?? {};

  if (!token) {
    return res.status(400).json({
      success: false,
      error: 'Token is required'
    });
  }

  try {
    if (!cashu.isValidTokenFormat(token)) {
      return res.status(400).json({
        success: false,
        error: 'Invalid token format. Must be a valid Cashu token'
      });
    }

    const decoded = await cashu.parseToken(token);
    const mintUrl = decoded.mint;

    let spent = false;
    try {
      const spendabilityCheck = await cashu.checkTokenSpendable(token);
      spent = !spendabilityCheck.spendable || spendabilityCheck.spendable.length === 0;
    } catch (error) {
      console.warn('Spendability check failed:', error.message);
      
      const errorString = error.message || error.toString();
      
      if (errorString.includes('TOKEN_SPENT:')) {
        console.log('Token determined to be spent by CashuComponent');
        spent = true;
      } else if (errorString.includes('Token validation failed at mint:')) {
        console.log('Token validation failed at mint - assuming token is still valid (might be invalid format)');
        spent = false;
      } else if (errorString.includes('not supported') ||
                 errorString.includes('endpoint not found') ||
                 errorString.includes('may still be valid') ||
                 errorString.includes('does not support spendability checking')) {
        console.log('Mint does not support spendability checking - assuming token is valid');
        spent = false;
      } else {
        console.log('Unknown error - assuming token is valid');
        spent = false;
      }
    }
    
    res.json({
      success: true,
      decoded: {
        mint: decoded.mint,
        totalAmount: decoded.totalAmount,
        numProofs: decoded.numProofs,
        denominations: decoded.denominations,
        format: decoded.format,
        spent
      },
      mint_url: mintUrl
    });
  } catch (error) {
    res.status(400).json({
      success: false,
      error: error.message
    });
  }
});

module.exports = router;