package game

import (
	"encoding/json"
	"os"
	"strings"
	"testing"
)

// eventsJSON renders a result's events for comparison. Two battles that played
// out identically serialize identically, which is exactly the property a
// replayed report has to have.
func eventsJSON(t *testing.T, res *BattleResult) string {
	t.Helper()
	b, err := json.Marshal(res.Events)
	if err != nil {
		t.Fatal(err)
	}
	return string(b)
}

// A report survives a trip through JSON and rebuilds the same game: same decks,
// same shop, same log.
func TestDebugReportRoundTrip(t *testing.T) {
	g, p1, p2 := testGame(t)
	forceBattle(t, g,
		[]Card{g.realPet(t, "Mosquito"), g.pet("Tank", 4)},
		[]Card{g.realPet(t, "Dolphin"), g.pet("Wall", 3)},
	)

	rep, err := g.DebugReport()
	if err != nil {
		t.Fatal(err)
	}
	blob, err := rep.JSON()
	if err != nil {
		t.Fatal(err)
	}
	back, err := ParseDebugReport(blob)
	if err != nil {
		t.Fatal(err)
	}

	if back.Summary.Code != g.Code || back.Summary.Round != g.Round {
		t.Fatalf("summary lost the game's identity: %+v", back.Summary)
	}
	if got, want := len(back.Summary.Seats), len(g.Players); got != want {
		t.Fatalf("summary lists %d seats, the table has %d", got, want)
	}
	if back.Summary.LogEntries != len(g.Log) || back.Summary.LogEntries == 0 {
		t.Fatalf("summary says %d log entries, the game has %d", back.Summary.LogEntries, len(g.Log))
	}

	restored, err := back.Game()
	if err != nil {
		t.Fatal(err)
	}
	for _, want := range []*Player{p1, p2} {
		got := restored.PlayerByID(want.ID)
		if got == nil {
			t.Fatalf("seat %d didn't survive the round trip", want.Seat)
		}
		if len(got.Deck) != len(want.Deck) {
			t.Fatalf("seat %d came back with %d cards, had %d", want.Seat, len(got.Deck), len(want.Deck))
		}
		for i := range want.Deck {
			if got.Deck[i].ID != want.Deck[i].ID || got.Deck[i].Name != want.Deck[i].Name {
				t.Fatalf("seat %d card %d came back as %+v, was %+v", want.Seat, i, got.Deck[i], want.Deck[i])
			}
		}
	}
	if len(restored.Battles) != len(g.Battles) {
		t.Fatalf("restored %d battles, the round had %d", len(restored.Battles), len(g.Battles))
	}

	// Each Game() is a fresh copy: mutating one must not disturb the report.
	restored.Players[0].Deck = nil
	again, err := back.Game()
	if err != nil {
		t.Fatal(err)
	}
	if len(again.Players[0].Deck) == 0 {
		t.Fatal("Game() handed out a shared copy — poking one restore emptied the next")
	}
}

// Replaying a report's battle reproduces it exactly — the same dice, so the
// same events, in the same order, with the same text. This is the property the
// whole report rests on: whatever the player saw, we see again.
func TestDebugReportReplaysBattleExactly(t *testing.T) {
	// No RollDie override: the rocks below roll for real, and only the recorded
	// tape can make the replay land on the same faces.
	g, _, _ := testGame(t)
	original := forceBattle(t, g,
		[]Card{g.realPet(t, "Dolphin"), g.realPet(t, "Mosquito"), g.pet("Tank", 4)},
		[]Card{g.realPet(t, "Mosquito"), g.pet("Wall", 5), g.realPet(t, "Dolphin")},
	)
	if len(original.Draws) == 0 {
		t.Fatal("a battle full of rocks recorded no dice at all")
	}

	rep, err := g.DebugReport()
	if err != nil {
		t.Fatal(err)
	}
	replay, err := rep.ReplayBattle(0)
	if err != nil {
		t.Fatal(err)
	}
	if got, want := eventsJSON(t, replay), eventsJSON(t, original); got != want {
		t.Fatalf("the replay diverged from the recording:\n got %s\nwant %s", got, want)
	}
	if replay.WinnerSeat != original.WinnerSeat {
		t.Fatalf("replay winner seat %d, recorded %d", replay.WinnerSeat, original.WinnerSeat)
	}
	if len(replay.Draws) != len(original.Draws) {
		t.Fatalf("replay rolled %d dice, the recording has %d", len(replay.Draws), len(original.Draws))
	}
	for i, d := range original.Draws {
		if replay.Draws[i] != d {
			t.Fatalf("draw %d replayed as %d, was %d", i, replay.Draws[i], d)
		}
	}

	// ReplayResult works off the result alone, without the surrounding game —
	// the shape of the fight is identical, only the player names differ.
	loose := ReplayResult(original)
	if loose == nil {
		t.Fatal("ReplayResult refused a well-formed result")
	}
	if loose.WinnerSeat != original.WinnerSeat || len(loose.Events) != len(original.Events) {
		t.Fatalf("ReplayResult diverged: winner %d (want %d), %d events (want %d)",
			loose.WinnerSeat, original.WinnerSeat, len(loose.Events), len(original.Events))
	}
}

// The workflow the report's own instructions describe: save the JSON, load it
// back from disk in a test, replay the battle.
func TestDebugReportFromFile(t *testing.T) {
	g, _, _ := testGame(t)
	original := forceBattle(t, g,
		[]Card{g.realPet(t, "Dolphin"), g.pet("Tank", 4)},
		[]Card{g.pet("Wall", 3), g.realPet(t, "Mosquito")},
	)
	rep, err := g.DebugReport()
	if err != nil {
		t.Fatal(err)
	}
	blob, err := rep.JSON()
	if err != nil {
		t.Fatal(err)
	}
	path := t.TempDir() + "/" + rep.Filename()
	if err := os.WriteFile(path, blob, 0o644); err != nil {
		t.Fatal(err)
	}

	loaded, err := LoadDebugReportFile(path)
	if err != nil {
		t.Fatal(err)
	}
	replay, err := loaded.ReplayBattle(0)
	if err != nil {
		t.Fatal(err)
	}
	if got, want := eventsJSON(t, replay), eventsJSON(t, original); got != want {
		t.Fatalf("a report off disk replayed differently:\n got %s\nwant %s", got, want)
	}
	if _, err := loaded.ReplayBattle(7); err == nil {
		t.Fatal("replaying a battle that isn't in the report should fail, not panic")
	}
	if _, err := LoadDebugReportFile(path + ".nope"); err == nil {
		t.Fatal("loading a missing file should fail")
	}
}

// A battle's banked resources are cleared the moment the round ends, so a
// result has to carry them itself or a later replay fights a different battle.
func TestDebugReportReplayRestoresBankedResources(t *testing.T) {
	g, p1, _ := testGame(t)
	p1.PendingTrumpets = 2
	p1.Mana = 3
	p1.PendingApplesInPlay = 1
	original := forceBattle(t, g,
		[]Card{g.pet("Tank", 4)},
		[]Card{g.pet("Wall", 3)},
	)
	if p1.PendingTrumpets != 0 || p1.PendingApplesInPlay != 0 {
		// resolveBattles spends the banks; that's what makes recording them
		// on the result necessary in the first place.
		t.Log("banks cleared by the round, as expected")
	}
	if in := original.Inputs[0]; in.Trumpets != 2 || in.Mana != 3 || in.ApplesInPlay != 1 {
		t.Fatalf("the result didn't record what side 0 brought in: %+v", in)
	}

	rep, err := g.DebugReport()
	if err != nil {
		t.Fatal(err)
	}
	replay, err := rep.ReplayBattle(0)
	if err != nil {
		t.Fatal(err)
	}
	if got, want := eventsJSON(t, replay), eventsJSON(t, original); got != want {
		t.Fatalf("the replay fought a different battle than the recording:\n got %s\nwant %s", got, want)
	}
}

// Games saved before the engine recorded its dice are still in the database,
// and their battles can't be reproduced. Saying so beats handing back a battle
// that quietly differs from the one the player saw.
func TestDebugReportRefusesUnrecordedBattle(t *testing.T) {
	g, _, _ := testGame(t)
	forceBattle(t, g,
		[]Card{g.realPet(t, "Dolphin")},
		[]Card{g.pet("Wall", 3)},
	)
	// Strip the recording, the way a result written by an older build looks.
	g.Battles[0].Draws = nil
	g.Battles[0].StartCardID = 0
	if g.Battles[0].Replayable() {
		t.Fatal("a result with no recording claims to be replayable")
	}

	rep, err := g.DebugReport()
	if err != nil {
		t.Fatal(err)
	}
	_, err = rep.ReplayBattle(0)
	if err == nil {
		t.Fatal("replaying an unrecorded battle should fail loudly, not roll fresh dice")
	}
	if !strings.Contains(err.Error(), "predates") {
		t.Fatalf("the error should explain why it can't be replayed, got %q", err)
	}
	if !strings.Contains(rep.Text(), "NOT RECORDED") {
		t.Fatal("the text report should flag a battle it can't replay")
	}
	// Re-fighting it is still on offer, with fresh dice and no promises.
	if ReplayResult(g.Battles[0]) == nil {
		t.Fatal("ReplayResult should still re-fight an unrecorded battle")
	}
}

// The raw state blob out of the database is accepted as a report too, so
// anything game-shaped can be replayed.
func TestParseDebugReportAcceptsBareState(t *testing.T) {
	g, _, _ := testGame(t)
	blob, err := json.Marshal(g)
	if err != nil {
		t.Fatal(err)
	}
	rep, err := ParseDebugReport(blob)
	if err != nil {
		t.Fatal(err)
	}
	if rep.Summary.Code != g.Code {
		t.Fatalf("bare state parsed as game %q, want %q", rep.Summary.Code, g.Code)
	}
	if _, err := ParseDebugReport([]byte(`{"nothing":"here"}`)); err == nil {
		t.Fatal("a JSON object with no game in it should not parse as a report")
	}
	if _, err := ParseDebugReport([]byte(`not json`)); err == nil {
		t.Fatal("garbage should not parse as a report")
	}
}

// The text rendering is the artifact a human actually reads, so it has to name
// the cards in play, the log, and the battle — not just summarize.
func TestDebugReportTextCoversTheGame(t *testing.T) {
	g, p1, _ := testGame(t)
	forceBattle(t, g,
		[]Card{g.realPet(t, "Mosquito")},
		[]Card{g.pet("Wall", 9)},
	)
	rep, err := g.DebugReport()
	if err != nil {
		t.Fatal(err)
	}
	rep.Note = "the mosquito's rock vanished"
	text := rep.Text()
	for _, want := range []string{
		g.Code,                         // which game
		p1.Name,                        // who was playing
		"Mosquito",                     // what was on the table
		"Play: throw 1 Rock",           // and what it was supposed to do
		"the mosquito's rock vanished", // the reporter's note
		"=== Event log",                // the log
		"dice tape",                    // the recording that makes it replayable
		"ReplayBattle(0)",              // the paste-ready repro
	} {
		if !strings.Contains(text, want) {
			t.Fatalf("the report never mentions %q:\n%s", want, text)
		}
	}
}