package ai

import (
	"testing"

	"github.com/greyson/super-auto-pets-board-game/internal/game"
)

// playBotGame drives a full game with bots in both seats, the same way the
// server would: observe on every state change, then act when input is owed.
// It fails the test if a bot ever produces an illegal action or the game
// stops making progress.
func playBotGame(t *testing.T, levelA, levelB float64) *game.Game {
	t.Helper()
	g := game.New()
	pa, err := g.AddBot("Bot A", levelA)
	if err != nil {
		t.Fatalf("AddBot A: %v", err)
	}
	pb, err := g.AddBot("Bot B", levelB)
	if err != nil {
		t.Fatalf("AddBot B: %v", err)
	}
	bots := map[string]*Bot{pa.ID: New(levelA), pb.ID: New(levelB)}
	mems := map[string]*Memory{pa.ID: {}, pb.ID: {}}

	observe := func() {
		for _, p := range g.Players {
			v := g.ViewFor(p.ID)
			Observe(&v, mems[p.ID])
		}
	}
	observe()

	for steps := 0; g.Phase != game.PhaseGameOver; steps++ {
		if steps > 2000 {
			t.Fatalf("game made no progress; stuck in phase %s round %d", g.Phase, g.Round)
		}
		acted := false
		for _, p := range g.Players {
			v := g.ViewFor(p.ID)
			if !Pending(&v) {
				continue
			}
			act := bots[p.ID].Act(&v, mems[p.ID])
			if act == nil {
				t.Fatalf("bot %s owes an action in phase %s but returned none", p.Name, g.Phase)
			}
			if err := applyAction(g, p.ID, act); err != nil {
				t.Fatalf("bot %s illegal action %q in phase %s round %d: %v", p.Name, act.Type, g.Phase, g.Round, err)
			}
			observe()
			acted = true
			break // one action per iteration, like one message per broadcast
		}
		if !acted {
			t.Fatalf("no bot owes an action but the game is not over (phase %s)", g.Phase)
		}
	}
	return g
}

// applyAction mirrors the server's dispatch of bot actions onto the engine.
func applyAction(g *game.Game, playerID string, a *Action) error {
	switch a.Type {
	case "buy":
		return g.Buy(playerID, a.Row)
	case "sell":
		if g.Phase == game.PhaseCleanup {
			return g.CleanupSell(playerID, a.Cards)
		}
		return g.Sell(playerID, a.Cards)
	case "trade":
		return g.TradeStart(playerID, a.Cards)
	case "tradeChoose":
		return g.TradeChoose(playerID, a.Pick)
	case "pass":
		return g.Pass(playerID)
	case "arrange":
		return g.SubmitOrder(playerID, a.Order)
	case "ready":
		return g.AcknowledgeBattle(playerID)
	}
	return game.ErrInvalidAction
}

// TestBotsFinishGames plays complete games at each difficulty pairing. This
// is the main safety net: every phase, every action type, every round, with
// two independent AIs generating whatever situations they generate.
func TestBotsFinishGames(t *testing.T) {
	for _, levels := range [][2]float64{{1, 1}, {0.25, 1}, {0, 0}, {0.6, 0.25}} {
		for range 3 {
			g := playBotGame(t, levels[0], levels[1])
			if g.Round != game.MaxRounds {
				t.Errorf("game ended on round %d, want %d", g.Round, game.MaxRounds)
			}
		}
	}
}

// TestObserveTracksOpponentDeck checks the memory's opponent model against
// the opponent's real deck after known public actions. The model may only
// contain information a human spectator would have.
func TestObserveTracksOpponentDeck(t *testing.T) {
	g := game.New()
	pa, _ := g.AddBot("Bot A", 1)
	pb, _ := g.AddBot("Bot B", 1)
	mem := &Memory{}
	obs := func() {
		v := g.ViewFor(pa.ID)
		Observe(&v, mem)
	}
	obs()

	// Whoever holds priority shops first; walk both players through buys.
	first, second := g.Players[g.PrioritySeat], g.Players[1-g.PrioritySeat]
	for range 3 { // 3 coins each, alternating
		for _, p := range []*game.Player{first, second} {
			if err := g.Buy(p.ID, 0); err != nil {
				t.Fatalf("buy: %v", err)
			}
			obs()
		}
	}

	// The model of B's deck must now match B's real deck card-for-card:
	// every buy was public (and buy effects like Otter's apple are printed
	// on the card).
	assertModelMatches(t, mem, pb)

	// Play out the round; the battle lineup resync must also match.
	for g.Phase == game.PhaseCleanup {
		t.Fatal("unexpected cleanup with 3 buys")
	}
	for _, p := range g.Players {
		ids := make([]string, len(p.Deck))
		for i, c := range p.Deck {
			ids[i] = c.ID
		}
		if err := g.SubmitOrder(p.ID, ids); err != nil {
			t.Fatalf("submit: %v", err)
		}
		obs()
	}
	if g.Phase != game.PhaseBattle {
		t.Fatalf("phase = %s, want battle", g.Phase)
	}
	obs()
	for _, p := range g.Players {
		if err := g.AcknowledgeBattle(p.ID); err != nil {
			t.Fatalf("ack: %v", err)
		}
		obs()
	}
	// Round 2 shop: temporaries expired; model must match B's real deck.
	assertModelMatches(t, mem, pb)
}

// assertModelMatches requires the opponent model to agree with the real deck
// as a multiset of card names (IDs can legitimately differ for cards the bot
// reconstructed from public information).
func assertModelMatches(t *testing.T, mem *Memory, opp *game.Player) {
	t.Helper()
	want := map[string]int{}
	for _, c := range opp.Deck {
		want[c.Name]++
	}
	got := map[string]int{}
	for _, c := range mem.Opp.Known {
		got[c.Name]++
	}
	if len(mem.Opp.Hidden) != 0 {
		t.Errorf("model has %d hidden cards, want 0 (everything was public)", len(mem.Opp.Hidden))
	}
	for name, n := range want {
		if got[name] != n {
			t.Errorf("model has %d × %s, real deck has %d", got[name], name, n)
		}
	}
	for name, n := range got {
		if want[name] == 0 {
			t.Errorf("model claims %d × %s that the real deck lacks", n, name)
		}
	}
}

// TestSimulateBattleIsPure verifies rollouts don't corrupt anything the
// caller hands in.
func TestSimulateBattleIsPure(t *testing.T) {
	deckA := []game.Card{
		{ID: "a1", Kind: game.KindPet, Name: "Ant", Power: 1,
			Effects: []game.Effect{{Trigger: game.TriggerFaint, Action: game.ActionSummonTop, Card: "apple"}}},
	}
	deckB := []game.Card{
		{ID: "b1", Kind: game.KindPet, Name: "Duck", Power: 2},
	}
	res := game.SimulateBattle(1, 0, deckA, deckB, nil)
	if res == nil || res.WinnerSeat != 1 {
		t.Fatalf("expected seat 1 (Duck) to win, got %+v", res)
	}
	if len(deckA) != 1 || len(deckB) != 1 || deckA[0].ID != "a1" || deckB[0].ID != "b1" {
		t.Error("SimulateBattle mutated its input decks")
	}
}