import { type StyleSpecificationWithId } from "./definitions";

export class RevisionStore {
  revisions: StyleSpecificationWithId[];
  currentIdx: number;


  constructor(initialRevisions=[]) {
    this.revisions = initialRevisions;
    this.currentIdx = initialRevisions.length - 1;
  }

  get latest() {
    return this.revisions[this.revisions.length - 1];
  }

  get current() {
    return this.revisions[this.currentIdx];
  }

  addRevision(revision: StyleSpecificationWithId) {
    // clear any "redo" revisions once a change is made
    // and ensure current index is at end of list
    this.revisions = this.revisions.slice(0, this.currentIdx + 1);

    this.revisions.push(revision);
    this.currentIdx++;
    //}
  }

  undo() {
    if(this.currentIdx > 0) {
      this.currentIdx--;
    }
    return this.current;
  }

  redo() {
    if(this.currentIdx < this.revisions.length - 1) {
      this.currentIdx++;
    }
    return this.current;
  }
}