import { Doodler, Vector } from "@bearmetal/doodler";
import {
  getContextItem,
  getContextItemOrDefault,
  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 {
  BankLeft,
  BankRight,
  SBendLeft,
  SBendRight,
  StraightTrack,
} from "../../track/shapes.ts";
import { TrackSegment } from "../../track/system.ts";
import { clamp } from "../../math/clamp.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, (() => void) | undefined> = new Map();

  private currentSegment?: TrackSegment;
  private selectedSegment?: TrackSegment;
  private ghostSegment?: TrackSegment;
  private ghostRotated = false;
  private closestEnd?: End;

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

    // 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);
    //   });
    // }

    if (this.selectedSegment) {
      const segment = this.selectedSegment;
      const firstPoint = segment.points[0].copy();
      const mousePos = inputManager.getMouseLocationV();
      segment.points.forEach((p, i) => {
        const relativePoint = Vector.sub(p, firstPoint);
        p.set(mousePos);
        p.add(relativePoint);
      });

      const ends = track.findEnds();
      setContextItem("showEnds", true);
      const nearbyEnds = ends.filter((end) => {
        const dist = Vector.dist(end.pos, mousePos);
        return dist < 20 && end.segment !== segment;
      });
      let closestEnd = nearbyEnds[0];
      for (const end of nearbyEnds) {
        if (end === closestEnd) continue;
        const closestEndTangent = Vector.add(
          closestEnd.tangent.copy().mult(20),
          closestEnd.pos,
        );
        const endTangent = Vector.add(
          end.tangent.copy().rotate(Math.PI).mult(20),
          end.pos,
        );
        doodler.drawCircle(closestEndTangent, 4, { color: "red", weight: 1 });
        doodler.drawCircle(endTangent, 4, { color: "blue", weight: 1 });
        if (
          endTangent.dist(mousePos) < closestEndTangent.dist(mousePos) ||
          end.pos.dist(mousePos) < closestEnd.pos.dist(mousePos)
        ) {
          closestEnd = end;
        }
      }
      if (closestEnd !== this.closestEnd) {
        this.closestEnd = closestEnd;
        this.ghostSegment = undefined;
        this.ghostRotated = false;
      }
      if (closestEnd) {
        // doodler.drawCircle(closestEnd.pos, 4, { color: "green", weight: 1 });
        doodler.line(
          closestEnd.pos,
          Vector.add(closestEnd.pos, closestEnd.tangent.copy().mult(20)),
          { color: "green" },
        );
      }
      if (
        this.closestEnd
      ) {
        if (!this.ghostSegment) {
          this.ghostSegment = segment.copy();
          this.ghostRotated = false;
        }
        switch (this.closestEnd.frontOrBack) {
          case "front":
            this.ghostSegment.setPositionByPoint(
              this.closestEnd.pos,
              this.ghostSegment.points[0],
            );
            // this.ghostSegment.points[0] = this.closestEnd.pos;
            !this.ghostRotated && this.ghostSegment.rotateAboutPoint(
              this.closestEnd.tangent.heading(),
              this.ghostSegment.points[0],
            );
            this.ghostRotated = true;
            break;
          case "back":
            this.ghostSegment.setPositionByPoint(
              this.closestEnd.pos,
              this.ghostSegment.points[3],
            );
            // this.ghostSegment.points[3] = this.closestEnd.pos;
            !this.ghostRotated && this.ghostSegment.rotateAboutPoint(
              this.closestEnd.tangent.heading(),
              this.ghostSegment.points[3],
            );
            this.ghostRotated = true;
            break;
        }
        // } else if (closestEnd) {
        //   this.closestEnd = closestEnd;
      } else if (!this.closestEnd || !closestEnd) {
        this.ghostSegment = undefined;
        this.ghostRotated = false;
      }

      this.selectedSegment?.draw();
      if (this.ghostSegment) {
        doodler.drawWithAlpha(0.5, () => {
          if (!this.ghostSegment) return;
          this.ghostSegment.draw();
          if (getContextItemOrDefault("debug", false)) {
            const colors = getContextItem<string[]>("colors");
            for (
              const [i, point] of this.ghostSegment.points.entries() ?? []
            ) {
              doodler.fillCircle(point, 4, { color: colors[i + 3] });
            }
          }
        });
      }
    }

    // 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);
    // }

    // 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 dirToP1 = Vector.sub(p2, p1).normalize();
    //   const angleToP1 = dirToP1.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);

    //   const goodangle = clamp(
    //     angleToMouse - angleToP1,
    //     angleToP1 - .6,
    //     angleToP1 + .6,
    //   );
    //   if (
    //     // Math.abs(goodangle) < .6 &&
    //     p2DistToMouse > distToP3 &&
    //     p3DistToMouse > distToP4
    //   ) {
    //     {
    //       const dirToNewP3 = dirToP1.copy().rotate(
    //         goodangle / 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, dirToNewP3),
    //         {
    //           color: "red",
    //         },
    //       );
    //     }
    //     {
    //       const dirToMouse = Vector.sub(mousePos, p3).normalize();
    //       const dirToP3 = Vector.sub(p3, p2).normalize();
    //       const angleToP3 = dirToP3.heading();
    //       const goodangle = clamp(
    //         dirToMouse.heading() - angleToP3,
    //         angleToP3 - .6,
    //         angleToP3 + .6,
    //       );

    //       const dirToNewP4 = dirToP3.copy().rotate(
    //         goodangle / 2,
    //       );
    //       dirToNewP4.setMag(distToP4);
    //       p4.set(Vector.add(p3, dirToNewP4));
    //       doodler.line(p3, Vector.add(p3, dirToNewP4), { color: "green" });
    //     }
    //     segment.clampLength();
    //   }
    //   // doodler.fillText(
    //   //   segment.calculateApproxLength().toFixed(2),
    //   //   p2.copy().add(10, 0),
    //   //   100,
    //   // );
    // }

    const translation = new Vector(0, 0);

    if (inputManager.getKeyState("ArrowUp")) {
      translation.y -= 1;
    }
    if (inputManager.getKeyState("ArrowDown")) {
      translation.y += 1;
    }
    if (inputManager.getKeyState("ArrowLeft")) {
      translation.x -= 1;
    }
    if (inputManager.getKeyState("ArrowRight")) {
      translation.x += 1;
    }

    if (translation.x !== 0 || translation.y !== 0) {
      track.translate(translation);
    }

    track.draw(true);
    // TODO
    // Draw ui
    // Draw track points
    // Draw track tangents
  }
  override start(): void {
    setContextItem("trackSegments", [
      undefined,
      new StraightTrack(),
      new SBendLeft(),
      new SBendRight(),
      new BankLeft(),
      new BankRight(),
    ]);

    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(" ", () => {
      if (this.selectedSegment) {
        this.selectedSegment = undefined;
      } else {
        this.selectedSegment = new StraightTrack();
      }
    });

    inputManager.onMouse("left", () => {
      const track = getContextItem<TrackSystem>("track");
      if (this.ghostSegment && this.closestEnd) {
        const segment = this.ghostSegment.cleanCopy();

        switch (this.closestEnd.frontOrBack) {
          case "front":
            this.closestEnd.segment.frontNeighbours.push(segment);
            segment.backNeighbours.push(this.closestEnd.segment);
            break;
          case "back":
            this.closestEnd.segment.backNeighbours.push(segment);
            segment.frontNeighbours.push(this.closestEnd.segment);
            break;
        }
        track.registerSegment(segment);
        this.ghostSegment = undefined;
        this.closestEnd = undefined;
      } else if (this.selectedSegment) {
        track.registerSegment(this.selectedSegment);
        this.selectedSegment = new StraightTrack();
      } else {
        this.selectedSegment = undefined;
      }
    });

    // 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;
    // });

    inputManager.onNumberKey((i) => {
      console.log(i);
      const segments = getContextItem<TrackSegment[]>("trackSegments");
      this.selectedSegment = segments[i];
      this.ghostRotated = false;
      this.ghostSegment = undefined;
    });

    this.currentSegment = track.lastSegment;

    // TODO
    // Cache trains and save
  }
  override stop(): void {
    const inputManager = getContextItem<InputManager>("inputManager");
    inputManager.offKey("e");
    inputManager.offKey("w");
    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);
    setContextItem("trackSegments", undefined);
  }
}