import { Cursor } from "./cursor";
import type { StrandPath } from "./path";
import { Strand } from "./strand";
import { h, VNode } from "./vdom";
import { SelectionRange } from "./selectionRange";

export class EditorState {
  readonly content: Strand;
  readonly selection: SelectionRange;

  constructor(
    content = new Strand([]),
    selection: SelectionRange | Cursor = new SelectionRange()
  ) {
    this.content = content;
    this.selection =
      selection instanceof Cursor ? new SelectionRange(selection) : selection;
    content.parent = this;
  }

  /**
   * @deprecated This function is only for debugging purposes.
   */
  renderToDebugText(): string {
    return this.content.renderToDebugText();
  }

  /**
   * @deprecated This function is only for debugging purposes.
   */
  renderToDebugHTML(): VNode {
    return h("div", { class: "math" }, this.content.renderToDebugHTML());
  }

  /**
   * @deprecated This function is only for debugging purposes.
   */
  renderToDebugMathML(): VNode {
    return h("math", {}, this.content.renderToDebugMathML());
  }

  /**
   * Get the cursor position within a given token's child strand.
   * @param strandPath The StrandPath of the strand to check against.
   * @param cursor The cursor whose position is being queried.
   * @returns The position of the cursor within the strand, or null if the cursor is not within that strand.
   */
  getPositionOfCursorInStrand(
    strandPath: StrandPath,
    cursor: Cursor
  ): number | null {
    if (cursor.strandPath.length !== strandPath.length) {
      return null;
    }

    for (let i = 0; i < strandPath.length; i++) {
      const cursorLevel = cursor.strandPath[i];
      const targetLevel = strandPath[i];
      if (
        cursorLevel.tokenIndex !== targetLevel.tokenIndex ||
        cursorLevel.childIndex !== targetLevel.childIndex
      ) {
        return null;
      }
    }

    return cursor.pos;
  }
}