/**
 * Main React app logic
 */

import React, { useState, useEffect, useCallback } from "react";
import * as THREE from "three";
import { MTLLoader, OBJLoader } from "@hbis/three-obj-mtl-loader";

import Detail from "./Detail.js";
import Legend from "./Legend.js";
import buildGraph from "../graph.js";

export default function App() {
  const [db, setDb] = useState(null);
  const [node, setNode] = useState(null);
  const [graph, setGraph] = useState(null);
  const [selectedCategory, setSelectedCategory] = useState(null);
  const [detailVisible, setDetailVisible] = useState(null);

  /** Load the database */
  useEffect(async () => {
    const newDb = await loadDB();
    await loadObjects(newDb);
    setDb(newDb);
    setGraph(
      buildGraph({
        db: newDb,
        handlers: {
          click: handleClick,
        },
      })
    );
  }, []);

  /** Click to open a node */
  const handleClick = useCallback((node) => {
    setNode(node);
    setDetailVisible(true);
  });

  /** Click to close the media modal */
  const handleClose = useCallback((node) => {
    setDetailVisible(false);
  });

  /** Select or clear the category */
  const handleSelect = useCallback((category) => {
    if (category === selectedCategory) {
      setSelectedCategory(null);
      graph.onSelect(null);
    } else {
      setSelectedCategory(category);
      graph.onSelect(category);
    }
  });

  return (
    <div>
      <Detail node={node} visible={detailVisible} onClose={handleClose} />
      <Legend
        visible={!detailVisible}
        selected={selectedCategory}
        onSelect={handleSelect}
      />
    </div>
  );
}

async function loadDB() {
  const request = await fetch("/assets/db.json");
  return await request.json();
}

async function loadObjects(db) {
  await Promise.all(
    db.page.reduce((promises, item) => {
      if (item.threeObject) {
        promises.push(loadObject(item));
      }
      return promises;
    }, [])
  );
}

function loadObject(item) {
  return new Promise((resolve) => {
    let { path, file } = item.threeObject;
    path = "assets/" + path;
    const manager = new THREE.LoadingManager();
    manager.setURLModifier((url) => {
      if (!url.match("/")) {
        url = path + url;
      }
      return url;
    });
    const mtlLoader = new MTLLoader(manager);
    const objLoader = new OBJLoader(manager);
    mtlLoader.setMaterialOptions({ side: THREE.DoubleSide });
    mtlLoader.load(file.replace(".obj", ".mtl"), (materials) => {
      materials.preload();
      objLoader.setMaterials(materials);
      objLoader.load(file, (object) => {
        item.object = object;
        resolve();
      });
    });
  });
}