import { Doodler, Vector } from "@bearmetal/doodler";
import { getContextItem, setContextItem } from "../../lib/context.ts";
import { InputManager } from "../../lib/input.ts";
import { TrackSystem } from "../../track/system.ts";
import { State, StateMachine } from "../machine.ts";
import { States } from "./index.ts";
import { StraightTrack } from "../../track/shapes.ts";
import { TrackSegment } from "../../track/system.ts";

export class EditTrackState extends State<States> {
  override name: States = States.EDIT_TRACK;
  override validTransitions: Set<States> = new Set([
    States.RUNNING,
    States.PAUSED,
  ]);

  private heldEvents: Map<string | number, (() => void) | undefined> =
    new Map();

  private currentSegment?: TrackSegment;

  override update(dt: number): void {
    const inputManager = getContextItem<InputManager>("inputManager");
    const track = getContextItem<TrackSystem>("track");

    // For moving a segment, i.e. the currently active one
    // const segment = track.lastSegment;
    // if (segment) {
    //   const firstPoint = segment.points[0].copy();
    //   const { x, y } = inputManager.getMouseLocation();
    //   segment.points.forEach((p, i) => {
    //     const relativePoint = Vector.sub(p, firstPoint);
    //     p.set(x, y);
    //     p.add(relativePoint);
    //   });
    // }

    // manipulate only end of segment while maintaining length
    // const segment = track.lastSegment;
    // if (segment) {
    //   const p3 = segment.points[2];
    //   const p4 = segment.points[3];
    //   let curveLength = Math.round(segment.calculateApproxLength());
    //   this.startingLength = this.startingLength ?? curveLength;
    //   curveLength = this.startingLength;
    //   const { x, y } = inputManager.getMouseLocation();
    //   p4.set(x, y);
    //   const points = segment.calculateEvenlySpacedPoints(1);
    //   if (points.length > curveLength) p4.set(points[curveLength - 1]);

    //   // doodler.fillText(curveLength.toFixed(2), p3.copy().add(10, 0), 100);
    // }
    const doodler = getContextItem<Doodler>("doodler");

    // Adjust angles until tangent points to mouse
    const segment = this.currentSegment;
    if (segment) {
      segment.propagate();

      const mousePos = inputManager.getMouseLocationV();
      const p1 = segment.points[0];
      const p2 = segment.points[1];
      const p3 = segment.points[2];
      const p4 = segment.points[3];

      const prevp3 = p3.copy();
      const dirToMouse = Vector.sub(mousePos, p2).normalize();
      const angleToMouse = dirToMouse.heading();
      const angleToP1 = Vector.sub(p2, p1).heading();
      const p2DistToMouse = Vector.dist(p2, mousePos);
      const p3DistToMouse = Vector.dist(p3, mousePos);
      const distToP3 = Vector.dist(p2, p3);
      const distToP4 = Vector.dist(prevp3, p4);
      if (
        Math.abs(angleToMouse - angleToP1) < .6 &&
        p2DistToMouse > distToP3 &&
        p3DistToMouse > distToP4
      ) {
        {
          const dirToNewP3 = dirToMouse.copy().rotate(
            -(angleToMouse - angleToP1) / 2,
          );
          dirToNewP3.setMag(distToP3);
          p3.set(Vector.add(p2, dirToNewP3));
          doodler.line(p2, Vector.add(p2, dirToNewP3), { color: "blue" });
          doodler.line(p2, Vector.add(p2, dirToMouse.mult(100)), {
            color: "red",
          });
        }
        {
          const dirToMouse = Vector.sub(mousePos, p3).normalize();
          dirToMouse.setMag(distToP4);
          p4.set(Vector.add(p3, dirToMouse));
          doodler.line(p3, Vector.add(p3, dirToMouse), { color: "green" });
        }
        segment.clampLength();
      }
      doodler.fillText(
        segment.calculateApproxLength().toFixed(2),
        p2.copy().add(10, 0),
        100,
      );
    }

    track.draw(true);
    // TODO
    // Draw ui
    // Draw track points
    // Draw track tangents
  }
  override start(): void {
    const inputManager = getContextItem<InputManager>("inputManager");
    this.heldEvents.set("e", inputManager.offKey("e"));
    this.heldEvents.set("Escape", inputManager.offKey("Escape"));
    inputManager.onKey("e", () => {
      const state = getContextItem<StateMachine<States>>("state");
      state.transitionTo(States.RUNNING);
    });

    const track = getContextItem<TrackSystem>("track");
    setContextItem("trackCopy", track.copy());
    inputManager.onKey("Escape", () => {
      const trackCopy = getContextItem<TrackSystem>("trackCopy");
      setContextItem("track", trackCopy);
      setContextItem("trackCopy", undefined);
      const state = getContextItem<StateMachine<States>>("state");
      state.transitionTo(States.RUNNING);
    });

    inputManager.onKey("w", () => {
      const track = getContextItem<TrackSystem>("track");
      const segment = track.lastSegment;
      if (!segment) return;
      const n = new StraightTrack(segment.points[3]);
      const t = segment.tangent(1).heading();
      n.rotate(t);
      segment.frontNeighbours.push(n);
      track.registerSegment(n);
      this.currentSegment = n;
    });

    inputManager.onKey("1", () => {
      this.currentSegment = track.firstSegment;
    });

    this.currentSegment = track.lastSegment;

    // TODO
    // Cache trains and save
  }
  override stop(): void {
    const inputManager = getContextItem<InputManager>("inputManager");
    inputManager.offKey("e");
    inputManager.offKey("Escape");
    if (this.heldEvents.size > 0) {
      for (const [key, cb] of this.heldEvents) {
        if (cb) {
          getContextItem<InputManager>("inputManager").onKey(key, cb);
        }
        this.heldEvents.delete(key);
      }
    }
    setContextItem("trackCopy", undefined);
  }
}