/**
 * Dependencies
 */
 
var revalidator = require('revalidator')
  , isIdentifier = require('./storage').isIdentifier
;

/**
 * Validate the attached resource and request.
 */
 
module.exports = function (req, res, next) {
  var method = req.method
    , resource = req.resource
    , validation
    , err
  ;
  
  // rewrite queries from references
  if(req.references && req.references.length && isIdentifier(req.references[0])) {
    // if the first reference is an id
    // rewrite the query to pull it
    req.query._id = req.references[0];
    req.one = true;
  }
  
  // root (or local) should skip validation
  if(req.isRoot || !req.isRemote) return next();
  
  // skip without a resource
  if(!resource) return next({error: 'Could not find a resource to validate.', status: 404});
  
  // if modifying data, require an id
  if((req.method === 'PUT' || req.method === 'DELETE') && (!req.query || !req.query._id)) {
    return next({error: 'An _id must be included when modifying a resource.'});      
  }
  
  // if trying to write data
  if((method === 'POST' || method === 'PUT') && resource && resource.properties) {
    
    // validate JSON
    validation = revalidator.validate(req.body, resource);
    err = validation.valid ? err : validation;
    next(err);
  } else {
    // continue
    next(err);
  }

}