import { describe, expect, it } from "vitest";
import {
  applyCommand,
  activePlayer,
  createGame,
  boardView,
  type Command,
  type GameState,
  type PlayerId,
} from "../src/game";
import { cellKey, edgeKey, hasLineOfSight, neighbor, type Side } from "../src/board";
import type { CardInstance } from "../src/cards";

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

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;
}

/** Test surgery: put a specific card into a player's hand (swapping one out). */
function giveCard(state: GameState, playerId: PlayerId, cardId: string, tag = "T"): CardInstance {
  const p = state.players.find((p) => p.id === playerId)!;
  const instance = { instanceId: `${cardId}#${tag}`, cardId };
  p.hand[0] = instance;
  return instance;
}

/** Advance past round 1 (both players just end their turns). */
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 });
  expect(state.turn.round).toBe(2);
  return state;
}

/** Put attacker and defender in mutual LOS (same square works for spells too). */
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 };
}

describe("attack spells", () => {
  it("fireball does 5 flat damage when unopposed", () => {
    let { state } = newGame();
    state = toRound2(state);
    const { attacker, defender } = faceOff(state);
    const fb = giveCard(state, attacker, "fireball");
    state = must(state, attacker, { type: "cast", instanceId: fb.instanceId, target: { kind: "player", playerId: defender } });
    expect(state.stack).not.toBeNull();
    state = must(state, defender, { type: "pass" });
    expect(state.stack).toBeNull();
    expect(state.players.find((p) => p.id === defender)!.life).toBe(10);
  });

  it("fireball destroys carried magic stones only if damage gets through", () => {
    let { state } = newGame();
    state = toRound2(state);
    const { attacker, defender } = faceOff(state);
    const fb = giveCard(state, attacker, "fireball");
    const d = state.players.find((p) => p.id === defender)!;
    d.hand[0] = { instanceId: "powerstone#T", cardId: "powerstone" };
    d.hand[1] = { instanceId: "full-shield#T", cardId: "full-shield" };

    state = must(state, attacker, { type: "cast", instanceId: fb.instanceId, target: { kind: "player", playerId: defender } });
    // Full shield stops everything -> stones survive.
    state = must(state, defender, { type: "counteract", instanceId: "full-shield#T" });
    state = must(state, attacker, { type: "pass" });
    state = must(state, defender, { type: "pass" });
    const after = state.players.find((p) => p.id === defender)!;
    expect(after.life).toBe(15);
    expect(after.hand.some((c) => c.cardId === "powerstone")).toBe(true);
  });

  it("lightning blast deals number-card damage and stuns", () => {
    let { state } = newGame();
    state = toRound2(state);
    const { attacker, defender } = faceOff(state);
    const lb = giveCard(state, attacker, "lightning-blast");
    const a = state.players.find((p) => p.id === attacker)!;
    a.hand[1] = { instanceId: "number-4#T", cardId: "number-4" };

    state = must(state, attacker, {
      type: "cast", instanceId: lb.instanceId, numberInstanceId: "number-4#T",
      target: { kind: "player", playerId: defender },
    });
    state = must(state, defender, { type: "pass" });
    const d = state.players.find((p) => p.id === defender)!;
    expect(d.life).toBe(11);
    expect(d.lostTurns).toBe(1);

    // The stunned player's next turn is skipped.
    state = must(state, attacker, { type: "endTurn", draw: 0 });
    expect(activePlayer(state).id).toBe(attacker); // defender was skipped
  });

  it("blunt halves damage rounding the result up; absorb takes 3 off", () => {
    let { state } = newGame();
    state = toRound2(state);
    const { attacker, defender } = faceOff(state);
    const fb = giveCard(state, attacker, "fireball");
    const d = state.players.find((p) => p.id === defender)!;
    d.hand[0] = { instanceId: "blunt#T", cardId: "blunt" };
    d.hand[1] = { instanceId: "absorb#T", cardId: "absorb" };

    state = must(state, attacker, { type: "cast", instanceId: fb.instanceId, target: { kind: "player", playerId: defender } });
    state = must(state, defender, { type: "counteract", instanceId: "blunt#T" });
    state = must(state, attacker, { type: "pass" });
    state = must(state, defender, { type: "counteract", instanceId: "absorb#T" });
    state = must(state, attacker, { type: "pass" });
    state = must(state, defender, { type: "pass" });
    // 5 -> blunt -> ceil(2.5)=3 -> absorb -> 0
    expect(state.players.find((p) => p.id === defender)!.life).toBe(15);
    // All damage stopped -> no stones logic, no stun, attack fully spent.
  });

  it("anti-anti nullifies a counteraction", () => {
    let { state } = newGame();
    state = toRound2(state);
    const { attacker, defender } = faceOff(state);
    const fb = giveCard(state, attacker, "fireball");
    const a = state.players.find((p) => p.id === attacker)!;
    a.hand[1] = { instanceId: "anti-anti#T", cardId: "anti-anti" };
    const d = state.players.find((p) => p.id === defender)!;
    d.hand[0] = { instanceId: "full-shield#T", cardId: "full-shield" };

    state = must(state, attacker, { type: "cast", instanceId: fb.instanceId, target: { kind: "player", playerId: defender } });
    state = must(state, defender, { type: "counteract", instanceId: "full-shield#T" });
    state = must(state, attacker, { type: "counteract", instanceId: "anti-anti#T" });
    state = must(state, defender, { type: "pass" });
    // Shield nullified: full 5 damage lands.
    expect(state.players.find((p) => p.id === defender)!.life).toBe(10);
  });

  it("full reflection sends the whole spell back at the caster", () => {
    let { state } = newGame();
    state = toRound2(state);
    const { attacker, defender } = faceOff(state);
    const fb = giveCard(state, attacker, "fireball");
    const d = state.players.find((p) => p.id === defender)!;
    d.hand[0] = { instanceId: "full-reflection#T", cardId: "full-reflection" };

    state = must(state, attacker, { type: "cast", instanceId: fb.instanceId, target: { kind: "player", playerId: defender } });
    state = must(state, defender, { type: "counteract", instanceId: "full-reflection#T" });
    state = must(state, attacker, { type: "pass" });
    state = must(state, defender, { type: "pass" });
    expect(state.players.find((p) => p.id === defender)!.life).toBe(15);
    expect(state.players.find((p) => p.id === attacker)!.life).toBe(10);
  });

  it("absorb spell nullifies the attack and takes the card into hand", () => {
    let { state } = newGame();
    state = toRound2(state);
    const { attacker, defender } = faceOff(state);
    const fb = giveCard(state, attacker, "fireball");
    const d = state.players.find((p) => p.id === defender)!;
    d.hand[0] = { instanceId: "absorb-spell#T", cardId: "absorb-spell" };

    state = must(state, attacker, { type: "cast", instanceId: fb.instanceId, target: { kind: "player", playerId: defender } });
    state = must(state, defender, { type: "counteract", instanceId: "absorb-spell#T" });
    const after = state.players.find((p) => p.id === defender)!;
    expect(after.life).toBe(15);
    expect(after.hand.some((c) => c.cardId === "fireball")).toBe(true);
    expect(state.stack).toBeNull();
  });

  it("waterbolt splits number value between damage and knockback", () => {
    let { state } = newGame();
    state = toRound2(state);
    const attacker = activePlayer(state);
    const defender = state.players.find((p) => p.id !== attacker.id)!;
    // Stand defender 1 east of attacker with open space behind (find a spot):
    // use same square then nudge — simplest robust arrangement: same square,
    // knockback direction defaults to none, so instead place east if open.
    defender.position = { ...attacker.position };
    const wb = giveCard(state, attacker.id, "waterbolt");
    const a = state.players.find((p) => p.id === attacker.id)!;
    a.hand[1] = { instanceId: "number-4#T", cardId: "number-4" };

    const bad = applyCommand(state, attacker.id, {
      type: "cast", instanceId: wb.instanceId, numberInstanceId: "number-4#T",
      target: { kind: "player", playerId: defender.id },
      params: { damage: 1, knockback: 1 },
    });
    expect(bad.ok).toBe(false); // must total 4

    state = must(state, attacker.id, {
      type: "cast", instanceId: wb.instanceId, numberInstanceId: "number-4#T",
      target: { kind: "player", playerId: defender.id },
      params: { damage: 3, knockback: 1 },
    });
    state = must(state, defender.id, { type: "pass" });
    expect(state.players.find((p) => p.id === defender.id)!.life).toBe(12);
  });

  it("requires line of sight for LOS attacks", () => {
    let { state } = newGame();
    state = toRound2(state);
    const attacker = activePlayer(state);
    const defender = state.players.find((p) => p.id !== attacker.id)!;
    // Find any cell without LOS from the attacker.
    const view = boardView(state);
    let hidden = null;
    for (const key of Object.keys(view.cells)) {
      const [x, y] = key.split(",").map(Number);
      if (!hasLineOfSight(view, attacker.position, { x: x!, y: y! })) { hidden = { x: x!, y: y! }; break; }
    }
    expect(hidden).not.toBeNull();
    defender.position = hidden!;
    const fb = giveCard(state, attacker.id, "fireball");
    const result = applyCommand(state, attacker.id, {
      type: "cast", instanceId: fb.instanceId, target: { kind: "player", playerId: defender.id },
    });
    expect(result.ok).toBe(false);
  });
});

describe("neutral spells", () => {
  it("create wall then destroy wall, with collapse damage", () => {
    let { state } = newGame();
    const caster = activePlayer(state);
    // Find an open edge adjacent to the caster.
    const view = boardView(state);
    let edge: { cell: typeof caster.position; side: Side } | null = null;
    for (const side of ["N", "S", "E", "W"] as Side[]) {
      const n = neighbor(caster.position, side);
      if (view.cells[cellKey(n)] && !(edgeKey(caster.position, side) in view.edges)) {
        edge = { cell: caster.position, side };
        break;
      }
    }
    expect(edge).not.toBeNull();

    const cw = giveCard(state, caster.id, "create-wall");
    state = must(state, caster.id, {
      type: "cast", instanceId: cw.instanceId,
      target: { kind: "edge", cell: edge!.cell, side: edge!.side },
    });
    expect(boardView(state).edges[edgeKey(edge!.cell, edge!.side)]).toBe("wall");

    // Destroying it hurts anyone standing beside it — the caster is adjacent.
    const dw = giveCard(state, caster.id, "destroy-wall");
    state = must(state, caster.id, {
      type: "cast", instanceId: dw.instanceId,
      target: { kind: "edge", cell: edge!.cell, side: edge!.side },
    });
    expect(boardView(state).edges[edgeKey(edge!.cell, edge!.side)]).toBe("open");
    expect(state.players.find((p) => p.id === caster.id)!.life).toBe(11);
  });

  it("neutrals do not consume the attack and multiple can be cast", () => {
    let { state } = newGame();
    const caster = activePlayer(state);
    const s1 = giveCard(state, caster.id, "speed", "T1");
    state = must(state, caster.id, { type: "cast", instanceId: s1.instanceId });
    expect(state.turn.attackUsed).toBe(false);
    const s2 = giveCard(state, caster.id, "speed", "T2");
    state = must(state, caster.id, { type: "cast", instanceId: s2.instanceId });
    expect(state.players.find((p) => p.id === caster.id)!.extraTurns).toBe(2);
  });

  it("speed grants an extra turn before play passes", () => {
    let { state } = newGame();
    const caster = activePlayer(state);
    const sp = giveCard(state, caster.id, "speed");
    state = must(state, caster.id, { type: "cast", instanceId: sp.instanceId });
    state = must(state, caster.id, { type: "endTurn", draw: 0 });
    expect(activePlayer(state).id).toBe(caster.id); // extra turn, same player
    state = must(state, caster.id, { type: "endTurn", draw: 0 });
    expect(activePlayer(state).id).not.toBe(caster.id);
  });
});

describe("stack discipline", () => {
  it("locks other commands while an attack is unresolved", () => {
    let { state } = newGame();
    state = toRound2(state);
    const { attacker, defender } = faceOff(state);
    const fb = giveCard(state, attacker, "fireball");
    state = must(state, attacker, { type: "cast", instanceId: fb.instanceId, target: { kind: "player", playerId: defender } });
    // Attacker cannot move while awaiting the defender.
    expect(applyCommand(state, attacker, { type: "move", direction: "N" }).ok).toBe(false);
    // Defender cannot move either — only counteract or pass.
    expect(applyCommand(state, defender, { type: "move", direction: "N" }).ok).toBe(false);
  });

  it("unimplemented cards refuse to cast with a clear error", () => {
    let { state } = newGame();
    const caster = activePlayer(state);
    const card = giveCard(state, caster.id, "chaos"); // expansion1, unimplemented
    const result = applyCommand(state, caster.id, { type: "cast", instanceId: card.instanceId });
    expect(result.ok).toBe(false);
    if (!result.ok) expect(result.error).toMatch(/not implemented/);
  });
});