import type { Vec2 } from '../geometry/Vec2';
import { formatAccuracy } from '../cutting/AccuracyCalculator';
import type { StageResult } from './StageSession';
import { CRUSH, crushScore, type CrushContact } from './Crush';
import { BEAR_CRUSH, type BearColor, type BearCrushDefinition } from './BearCrush';

export type BearOutcome = 'pending'|'safe'|'crushed'|'mistake';
export interface BearJellyState {
  id:number; color:BearColor; arrival:number; x:number; score:number|null;
  contact:CrushContact|null; impactAge:number; outcome:BearOutcome;
}
export interface BearCrushSnapshot {
  clock:number; phase:'idle'|'down'|'contact'|'up'; strikeTime:number; strikes:number;
  mistakes:number; done:boolean; jellies:BearJellyState[];
}
export interface BearImpact { kind:'contact'|'missed'|'empty'; id:number|null; color:BearColor|null; score:number; contact:CrushContact|null; mistake:boolean }

const CYCLE=BEAR_CRUSH.down+BEAR_CRUSH.hold+BEAR_CRUSH.up;

/** 이동 시계는 타격 중에도 멈추지 않는다. 입력과 접촉 사이 위치를 실제 시간으로 적분한다. */
export class BearCrushSession {
  private clock=0;
  private strikeTime=CYCLE;
  private pending=false;
  private strikes=0;
  private mistakes=0;
  private readonly jellies:BearJellyState[];
  private readonly minX:number;
  constructor(private readonly outline:readonly Vec2[],readonly definition:BearCrushDefinition) {
    const {colors,intervals,speed}=definition;
    const xs=outline.map(p=>p.x);
    this.minX=Math.min(...xs);
    const span=Math.max(...xs)-this.minX+2*CRUSH.halfWidth;
    if(outline.length<3||colors.length<3||intervals.length!==colors.length-1||
      (definition.goal==='spare'&&(!colors.includes(definition.protectedColor)||colors.filter(c=>c===definition.protectedColor).length<2||colors.every(c=>c===definition.protectedColor)))||
      !Number.isFinite(speed)||speed<=0||
      intervals.some(t=>!Number.isFinite(t)||t*speed<=span)) throw new Error('곰 젤리 구성 또는 등장 간격이 유효하지 않음');
    let arrival=BEAR_CRUSH.firstArrival;
    this.jellies=colors.map((color,id)=>{
      if(id>0)arrival+=intervals[id-1];
      return {id,color,arrival,x:-arrival*speed,score:null,contact:null,impactAge:0,outcome:'pending'};
    });
  }
  get done():boolean {return this.jellies.every(j=>j.outcome!=='pending')&&this.strikeTime>=CYCLE-1e-9;}
  press():boolean {
    if(this.strikeTime<CYCLE-1e-9||this.done)return false;
    this.strikeTime=0;this.pending=true;this.strikes++;
    return true;
  }
  /** 큰 dt도 접촉 순간에서 나눠 적분하므로 한 프레임 지연으로 판정이 바뀌지 않는다. */
  advance(dt:number):BearImpact[] {
    if(!Number.isFinite(dt)||dt<0)return [];
    const events:BearImpact[]=[];
    const untilContact=this.pending?Math.max(0,BEAR_CRUSH.down-this.strikeTime):Infinity;
    if(untilContact<=dt) {
      events.push(...this.step(untilContact));
      events.push(this.contact());
      events.push(...this.step(dt-untilContact));
    } else events.push(...this.step(dt));
    return events;
  }
  private step(dt:number):BearImpact[] {
    if(dt<=0)return [];
    const events:BearImpact[]=[];
    this.clock+=dt;
    this.strikeTime=Math.min(CYCLE,this.strikeTime+dt);
    for(const j of this.jellies) {
      j.x=(this.clock-j.arrival)*this.definition.speed;
      if(j.contact)j.impactAge+=dt;
      if(j.outcome==='pending'&&j.x+this.minX>CRUSH.halfWidth) {
        j.score=0;
        j.outcome=this.isProtected(j.color)?'safe':'mistake';
        if(j.outcome==='mistake') {
          this.mistakes++;
          events.push({kind:'missed',id:j.id,color:j.color,score:0,contact:null,mistake:true});
        }
      }
    }
    return events;
  }
  private contact():BearImpact {
    this.pending=false;
    for(const j of this.jellies) {
      if(j.outcome!=='pending')continue;
      const hit=crushScore(this.outline,j.x);
      if(hit.score<=1e-8)continue;
      j.score=hit.score;j.contact=hit.contact;j.impactAge=0;
      const mistake=this.isProtected(j.color)||hit.score<BEAR_CRUSH.minCrush;
      j.outcome=mistake?'mistake':'crushed';
      if(mistake)this.mistakes++;
      return {kind:'contact',id:j.id,color:j.color,score:hit.score,contact:hit.contact,mistake};
    }
    return {kind:'empty',id:null,color:null,score:0,contact:null,mistake:false};
  }
  snapshot():BearCrushSnapshot {
    const t=this.strikeTime;
    return {clock:this.clock,phase:t>=CYCLE-1e-9?'idle':t<BEAR_CRUSH.down?'down':t<BEAR_CRUSH.down+BEAR_CRUSH.hold?'contact':'up',
      strikeTime:t,strikes:this.strikes,mistakes:this.mistakes,done:this.done,
      jellies:this.jellies.map(j=>({...j,contact:j.contact?{...j.contact}:null}))};
  }
  private isProtected(color:BearColor):boolean {
    return this.definition.goal==='spare'&&color===this.definition.protectedColor;
  }
  getResult():StageResult {
    const others=this.jellies.filter(j=>!this.isProtected(j.color));
    const accuracy=others.reduce((sum,j)=>sum+(j.score??0),0)/others.length;
    const stars=this.mistakes?0:accuracy>=BEAR_CRUSH.threeStars?3:accuracy>=BEAR_CRUSH.twoStars?2:1;
    return {accuracy,displayAccuracy:formatAccuracy(accuracy),stars,isClear:stars>0,
      pieceCount:others.filter(j=>j.outcome==='crushed').length,targetPieceCount:others.length,
      guideScores:Object.fromEntries(this.jellies.map(j=>[String(j.id),j.score??0]))};
  }
}