const Filters = require('./filters.js');
const EnvironmentVariables = require('./environmentVariables.js');

class Field {
   constructor(rawValue, environmentVariables) {
      this.rawValue = rawValue;
      this.filters = new Filters(rawValue);
      this.valueWithoutFilters = this.filters.removeFiltersFromValue();
      this.environmentVariables = new EnvironmentVariables(environmentVariables);
   }

   get value() {
      if (this.filters.isEmpty()) {
         return this.valueWithoutFilters;
      }

      if (this.filters.has('base64') && !this.filters.has('env')) {
         return Field.base64Decode(this.valueWithoutFilters);
      }

      if (this.environmentVariables.has(this.valueWithoutFilters) &&
          this.environmentVariables.get(this.valueWithoutFilters) === '') {
         return undefined;
      }

      if (!this.filters.has('base64') && this.filters.has('env')) {
         if (this.environmentVariables.has(this.valueWithoutFilters)) {
            return this.environmentVariables.get(this.valueWithoutFilters);
         }
         return undefined;
      }

      if (this.filters.has('env') && this.filters.has('base64')) {
         if (this.environmentVariables.has(this.valueWithoutFilters)) {
            const encodedEnvironmentVariable = this.environmentVariables.get(this.valueWithoutFilters);
            return Field.base64Decode(encodedEnvironmentVariable);
         }
         return undefined;
      }

      return this.valueWithoutFilters;
   }

   static base64Decode(string) {
      return new Buffer(string, 'base64').toString('utf-8');
   }
}

module.exports = Field;