import { Injectable } from '@angular/core';

import {
  FamilyTreeNode
} from './family-tree-builder';

import { LayoutNode } from '../models/layoutnode';
import { Family } from '../models/family';

@Injectable({
  providedIn: 'root'
})
export class FamilyTreeLayoutService {

  private readonly NODE_WIDTH = 140;
  private readonly NODE_HEIGHT = 70;

  private readonly HORIZONTAL_GAP = 200;
  private readonly VERTICAL_GAP = 200;

  private readonly SPOUSE_GAP = 180;  

  private processedCouples = new Set<string>();
  private currentX = 0;


  buildLayout(
    roots: FamilyTreeNode[]
  ): LayoutNode[] {

    this.currentX = 0;

    this.processedCouples.clear();

    const result: LayoutNode[] = [];

    const visited = new Set<string>();

    roots.forEach(root => {

      this.layoutNode(
        root,
        0,
        result,
        visited
      );

      this.currentX +=
        this.HORIZONTAL_GAP;
    });

    return result;
  }

  private layoutNode(
    node: FamilyTreeNode,
    depth: number,
    result: LayoutNode[],
    visited: Set<string>
  ): number {

    if (visited.has(node.family.id)) {

      const existing = result.find(
        x => x.familyId === node.family.id
      );

      return existing?.x ?? 0;
    }

    visited.add(node.family.id);

    const children = node.children;

    let x: number;

    if (children.length === 0) {

      x = this.currentX;

      this.currentX +=
        this.HORIZONTAL_GAP;

    } else {

      const childXs =
        children.map(child =>
          this.layoutNode(
            child,
            depth + 1,
            result,
            visited
          )
        );

      x =
        (Math.min(...childXs) +
          Math.max(...childXs))
        / 2;
    }

    const y =
      depth *
      this.VERTICAL_GAP;

    let spouseX: number | undefined;
    let spouse: Family | undefined;

    if (node.spouses.length > 0) {

      const spouseNode =
        node.spouses[0];

      const coupleKey =
        [
          node.family.id,
          spouseNode.family.id
        ]
          .sort()
          .join('-');

      if (
        !this.processedCouples.has(
          coupleKey
        )
      ) {

        this.processedCouples.add(
          coupleKey
        );

        spouse =
          spouseNode.family;

        spouseX =
          x + this.SPOUSE_GAP;
      }
    }

    result.push({

      familyId: node.family.id,

      family: node.family,

      spouse,

      depth,

      x,
      y,

      spouseX,

      width: this.NODE_WIDTH,

      height: this.NODE_HEIGHT

    });

    return x;
  }

}