// Shared test rig: a deterministic two-wizard game plus the moves every
// suite makes — force a card into a hand, burn the no-combat first round,
// stand two wizards face to face, cast-and-let-resolve.

import {
  applyCommand,
  activePlayer,
  boardView,
  createGame,
  type Command,
  type GameState,
  type PlayerId,
} from "../src/game";
import { cellKey, SIDES, stepTarget, type Cell, type Side } from "../src/board";
import type { CardInstance } from "../src/cards";

export function newGame(seed = 42, players: PlayerId[] = ["alice", "bob"]) {
  return createGame({ playerIds: players, seed, sets: ["basic"] });
}

export function newExpansionGame(seed = 42, players: PlayerId[] = ["alice", "bob"]) {
  return createGame({ playerIds: players, seed, sets: ["basic", "expansion1"] });
}

export function must(state: GameState, player: PlayerId, command: Command): GameState {
  const result = applyCommand(state, player, command);
  if (!result.ok) throw new Error(`command failed: ${result.error}`);
  return result.state;
}

export function giveCard(state: GameState, playerId: PlayerId, cardId: string, tag = "T", slot = 0): CardInstance {
  const p = state.players.find((p) => p.id === playerId)!;
  const instance = { instanceId: `${cardId}#${tag}`, cardId };
  p.hand[slot] = instance;
  return instance;
}

/** Burn the no-combat first round: both players pass their opening turn. */
export function toRound2(state: GameState): GameState {
  state = must(state, activePlayer(state).id, { type: "endTurn", draw: 0 });
  state = must(state, activePlayer(state).id, { type: "endTurn", draw: 0 });
  return state;
}

/** Stand the other wizard on the active one's square. */
export function faceOff(state: GameState): { attacker: PlayerId; defender: PlayerId } {
  const attacker = activePlayer(state);
  const defender = state.players.find((p) => p.id !== attacker.id)!;
  defender.position = { ...attacker.position };
  return { attacker: attacker.id, defender: defender.id };
}

/** Cast at a player and let it resolve uncountered. */
export function castAt(
  state: GameState, attacker: PlayerId, defender: PlayerId, card: CardInstance,
  extra: Partial<Extract<Command, { type: "cast" }>> = {},
): GameState {
  state = must(state, attacker, {
    type: "cast", instanceId: card.instanceId,
    target: { kind: "player", playerId: defender }, ...extra,
  });
  return must(state, defender, { type: "pass" });
}

/** An adjacent, walkable square holding no home, treasure, or wizard. */
export function emptyNeighborCell(state: GameState, of: Cell): { cell: Cell; side: Side } {
  const view = boardView(state);
  for (const side of SIDES) {
    const t = stepTarget(view, of, side);
    if (t.kind !== "step") continue;
    const key = cellKey(t.to);
    if (view.homes.some((h) => cellKey(h) === key)) continue;
    if (state.treasures.some((tr) => tr.position && cellKey(tr.position) === key)) continue;
    if (state.players.some((p) => cellKey(p.position) === key)) continue;
    return { cell: t.to, side };
  }
  throw new Error("no empty neighbor");
}