import { BalanceWeight, Facing, HandConnection, HandTo, PositionKind, facingAdjacent, facingRequireAdjacent } from "../interpreterCommon.js";
import { SemanticAnimationKind } from "../lowLevelMove.js";
import { Hand } from "../rendererConstants.js";
import { ISingleVariantMoveInterpreter, LowLevelMovesForAllDancers, MoveInterpreter, MoveInterpreterCtorArgs, SemanticPositionsForAllDancers, SingleVariantMoveInterpreter, Variant, VariantCollection, moveInterpreters } from "./_moveInterpreter.js";

const moveName = "balance";

class BalanceSingleVariant extends SingleVariantMoveInterpreter<Balance, typeof moveName> {
  private static readonly balanceOptions : [BalanceWeight, BalanceWeight | undefined, Hand | undefined][]= [
    // TODO Any others?
    [BalanceWeight.Forward, undefined, undefined],
    [BalanceWeight.Forward, BalanceWeight.Backward, undefined],
    // TODO Should be left/right/inside/outside hands?
    [BalanceWeight.Forward, BalanceWeight.Backward, Hand.Left],
    [BalanceWeight.Forward, BalanceWeight.Backward, Hand.Right],
    [BalanceWeight.Right, BalanceWeight.Backward, undefined],
    [BalanceWeight.Right, BalanceWeight.Left, undefined],
    [BalanceWeight.Left, BalanceWeight.Right, undefined],
  ];

  moveAsVariants(previousMoveVariant: string): VariantCollection {
    const res = new Map<string, Variant>();

    for (const [firstWeight, secondWeight, hand] of BalanceSingleVariant.balanceOptions) {
      // If balancing someone, need to know by which hand.
      if ((hand === undefined) !== (this.move.parameters.who === "everyone")) continue;
      try {
        res.set((firstWeight?.toString() ?? "") + (secondWeight?.toString() ?? "") + (hand === undefined ? "" : hand.toString() + "Hand"), {
          lowLevelMoves: this.moveAsLowLevelMovesWeights(firstWeight, secondWeight, hand),
          previousMoveVariant
        });
      }
      catch { }
    }

    return res;
  }

  moveAsLowLevelMovesWeights(firstWeight?: BalanceWeight, secondWeight?: BalanceWeight, hand?: Hand): LowLevelMovesForAllDancers {
    if (this.move.parameters.who !== "everyone") {
      return this.handlePairedMove(this.move.parameters.who, ({ startPos, withPos }) => {
        // TODO Does this need to support balancing inside/outside hands? If so how to identify them?
        const hands = hand === undefined ? startPos.hands : new Map<Hand, HandConnection>([[hand, {hand, to: HandTo.DancerForward}]]);

        const facing = facingRequireAdjacent(startPos, withPos, this.move.move);

        const startingPos = {...startPos, facing, hands};

        return this.combine([
          {
            beats: this.moveInterpreter.balancePartBeats,
            endPosition: { ...startingPos, balance: firstWeight, hands },
            movementPattern: { kind: SemanticAnimationKind.Linear },
          },
          {
            beats: this.moveInterpreter.balancePartBeats,
            endPosition: { ...startingPos, balance: secondWeight, hands },
            movementPattern: { kind: SemanticAnimationKind.Linear },
          },
        ], startingPos);
      });
    } else {
      return this.handleMove(({ startPos }) => {
        // TODO Use who to determine facing?
        // TODO Could be left to right, not back and forth?
        // TODO How to determine hand... by next move, I guess?
        if (startPos.kind === PositionKind.Circle && startPos.facing === Facing.CenterOfCircle) {
          if (firstWeight === BalanceWeight.Left || firstWeight === BalanceWeight.Right || firstWeight === BalanceWeight.Backward
            || secondWeight === BalanceWeight.Left || secondWeight === BalanceWeight.Right || secondWeight === BalanceWeight.Backward) {
            throw new Error("Balancing left or right in a circle is unsupported.");
          }
        }

        return this.combine([
          {
            beats: this.moveInterpreter.balancePartBeats,
            endPosition: { ...startPos, balance: firstWeight },
            movementPattern: { kind: SemanticAnimationKind.Linear },
          },
          {
            beats: this.moveInterpreter.balancePartBeats,
            endPosition: { ...startPos, balance: secondWeight },
            movementPattern: { kind: SemanticAnimationKind.Linear },
          },
        ], startPos);
      });
    }
  }
}

class Balance extends MoveInterpreter<typeof moveName> {
  public readonly balancePartBeats: number;

  constructor(args: MoveInterpreterCtorArgs<typeof moveName>) {
    super(args);

    this.balancePartBeats = this.move.beats / 2;
  }

  buildSingleVariantMoveInterpreter(startingPos: SemanticPositionsForAllDancers): ISingleVariantMoveInterpreter {
    return new BalanceSingleVariant(this, startingPos);
  }
}

moveInterpreters.set(moveName, Balance);