'use strict';

// Plugin
module.exports = function timestamp (schema, options) {
  options = options || (options === {});

  // Options
  var fields = {},
    createdPath = options.createdPath || 'created',
    modifiedPath = options.modifiedPath || 'modified',
    useVirtual = (options.useVirtual !== undefined) ? options.useVirtual : true;

  // Add paths to schema if not present
  if (!schema.paths[createdPath]) {
    fields[modifiedPath] = { type: Date };
  }
  if (useVirtual) {
    // Use the ObjectID for extracting the created time
    schema.virtual(createdPath).get(function () {
      return new Date(this._id.generationTime * 1000);
    });
  } else {
    if (!schema.paths[createdPath]) {
      fields[createdPath] = { 
        type: Date,
        default: Date.now 
      };
    }
  }
  schema.add(fields);

  // Update the modified timestamp on save
  schema.pre('save', function (next) {
    this[modifiedPath] = new Date();
    next();
  });
};