import BinaryStream from '../../common/binarystream';
import IndexEntry from './indexentry';

/**
 * A reference.
 */
export default class Reference {
  index: IndexEntry[] | null = null;
  entries: number = 0;
  id: number = 0;
  flags: number = 0;

  load(stream: BinaryStream, index: IndexEntry[]) {
    this.index = index;
    this.entries = stream.readUint32();
    this.id = stream.readUint32();
    this.flags = stream.readUint32();
  }

  /**
   * Get the entries this index entry references.
   */
  get() {
    if (this.index) {
      let id = this.id;

      // For empty references (e.g. Layer.imagePath)
      if (id === 0 || this.entries === 0) {
        return [];
      }

      return this.index[id].entries;
    }
  }

  /**
   * Get the first entry this index entry references.
   */
  first() {
    if (this.index) {
      let id = this.id;

      if (id !== 0 && this.entries !== 0) {
        let entries = this.index[id].entries;

        if (entries) {
          return entries[0];
        }
      }
    }
  }
}