package main

import (
	"bytes"
	"crypto/ed25519"
	"crypto/rand"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"io"
	"net/http"
	"os"
	"testing"
	"time"
)

// These tests drive a running server. Start it with:
//
//	ARCADE_DEV_FAUCET=1 go run ./cmd/arcade
//
// and run with ARCADE_E2E=http://localhost:8080. They are skipped otherwise so
// that `go test ./...` stays green without a live server.
func baseURL(t *testing.T) string {
	t.Helper()
	u := os.Getenv("ARCADE_E2E")
	if u == "" {
		t.Skip("set ARCADE_E2E to run end-to-end tests")
	}
	return u
}

type client struct {
	t     *testing.T
	base  string
	token string
	pub   ed25519.PublicKey
	priv  ed25519.PrivateKey
}

func newClient(t *testing.T) *client {
	t.Helper()
	pub, priv, err := ed25519.GenerateKey(rand.Reader)
	if err != nil {
		t.Fatal(err)
	}
	return &client{t: t, base: baseURL(t), pub: pub, priv: priv}
}

func (c *client) do(method, path string, body, out any) int {
	c.t.Helper()
	var buf io.Reader
	if body != nil {
		b, _ := json.Marshal(body)
		buf = bytes.NewReader(b)
	}
	req, err := http.NewRequest(method, c.base+path, buf)
	if err != nil {
		c.t.Fatal(err)
	}
	req.Header.Set("Content-Type", "application/json")
	if c.token != "" {
		req.Header.Set("Authorization", "Bearer "+c.token)
	}
	res, err := http.DefaultClient.Do(req)
	if err != nil {
		c.t.Fatal(err)
	}
	defer res.Body.Close()
	if out != nil {
		_ = json.NewDecoder(res.Body).Decode(out)
	}
	return res.StatusCode
}

func (c *client) signIn(nickname string) {
	c.t.Helper()
	pubHex := hex.EncodeToString(c.pub)

	var chal struct{ Challenge string }
	if code := c.do("POST", "/api/auth/challenge",
		map[string]string{"pubkey": pubHex}, &chal); code != 200 {
		c.t.Fatalf("challenge failed: %d", code)
	}
	nonce, _ := hex.DecodeString(chal.Challenge)
	sig := ed25519.Sign(c.priv, nonce)

	var res struct {
		Token string `json:"token"`
	}
	if code := c.do("POST", "/api/auth/verify", map[string]string{
		"pubkey": pubHex, "signature": hex.EncodeToString(sig), "nickname": nickname,
	}, &res); code != 200 {
		c.t.Fatalf("verify failed: %d", code)
	}
	c.token = res.Token
}

func (c *client) fund(msat int64) int64 {
	c.t.Helper()
	var res struct {
		BalanceMsat int64 `json:"balance_msat"`
	}
	if code := c.do("POST", "/api/dev/faucet",
		map[string]int64{"amount_msat": msat}, &res); code != 200 {
		c.t.Fatalf("faucet failed: %d (is ARCADE_DEV_FAUCET=1 set?)", code)
	}
	return res.BalanceMsat
}

func TestSignInAndFund(t *testing.T) {
	c := newClient(t)
	c.signIn("tester")
	if bal := c.fund(50_000_000); bal < 50_000_000 {
		t.Fatalf("balance after faucet = %d", bal)
	}
}

func TestUnauthenticatedRequestsRejected(t *testing.T) {
	c := newClient(t)
	var out map[string]any
	if code := c.do("GET", "/api/balance", nil, &out); code != 401 {
		t.Fatalf("unauthenticated balance returned %d, want 401", code)
	}
	if code := c.do("POST", "/api/bet",
		map[string]any{"game": "rocket", "stake_msat": 1000}, &out); code != 401 {
		t.Fatalf("unauthenticated bet returned %d, want 401", code)
	}
}

func TestCannotBetMoreThanBalance(t *testing.T) {
	c := newClient(t)
	c.signIn("broke")
	// No faucet call: balance is zero.
	var out map[string]any
	code := c.do("POST", "/api/bet",
		map[string]any{"game": "rocket", "stake_msat": 1_000_000}, &out)
	if code != 400 {
		t.Fatalf("betting without funds returned %d, want 400", code)
	}
}

// Play a full round: wait for a betting window, bet, and confirm the stake left
// the balance and the round eventually settles and reveals its seed.
func TestFullRoundLifecycleAndVerification(t *testing.T) {
	c := newClient(t)
	c.signIn("player")
	c.fund(50_000_000)

	const stake = 1_000_000
	var roundID int64

	deadline := time.Now().Add(90 * time.Second)
	for time.Now().Before(deadline) {
		var games struct {
			Rooms []struct {
				RoundID int64  `json:"round_id"`
				Game    string `json:"game"`
				State   string `json:"state"`
			} `json:"rooms"`
		}
		c.do("GET", "/api/games", nil, &games)

		for _, rm := range games.Rooms {
			if rm.Game != "rocket" || rm.State != "betting_open" {
				continue
			}
			var res struct {
				BalanceMsat int64  `json:"balance_msat"`
				Error       string `json:"error"`
			}
			if code := c.do("POST", "/api/bet", map[string]any{
				"game": "rocket", "stake_msat": stake, "nickname": "player",
			}, &res); code == 200 {
				roundID = rm.RoundID
			}
		}
		if roundID != 0 {
			break
		}
		time.Sleep(500 * time.Millisecond)
	}
	if roundID == 0 {
		t.Fatal("never managed to place a bet within 90s")
	}

	// Wait for the round to settle and expose its proof.
	var proof struct {
		Commitment  string   `json:"commitment"`
		ServerSeed  string   `json:"server_seed"`
		ClientSeed  string   `json:"client_seed"`
		Nonce       int64    `json:"nonce"`
		Participants []string `json:"participants"`
	}
	settled := false
	deadline = time.Now().Add(90 * time.Second)
	for time.Now().Before(deadline) {
		if code := c.do("GET", "/api/verify/"+itoa(roundID), nil, &proof); code == 200 {
			settled = true
			break
		}
		time.Sleep(500 * time.Millisecond)
	}
	if !settled {
		t.Fatal("round never settled")
	}

	// The revealed seed must match the commitment published before betting.
	seed, err := hex.DecodeString(proof.ServerSeed)
	if err != nil {
		t.Fatal(err)
	}
	sum := sha256.Sum256(seed)
	if hex.EncodeToString(sum[:]) != proof.Commitment {
		t.Fatalf("commitment mismatch:\n published %s\n actual    %s",
			proof.Commitment, hex.EncodeToString(sum[:]))
	}
	if len(proof.Participants) == 0 {
		t.Fatal("settled round lists no participants")
	}
}

// The books must balance at all times, which the health endpoint reports.
func TestLedgerStaysBalanced(t *testing.T) {
	c := newClient(t)
	var health struct {
		Status        string `json:"status"`
		LedgerSumMsat int64  `json:"ledger_sum_msat"`
	}
	if code := c.do("GET", "/api/health", nil, &health); code != 200 {
		t.Fatalf("health returned %d", code)
	}
	if health.LedgerSumMsat != 0 {
		t.Fatalf("ledger does not balance: sum = %d", health.LedgerSumMsat)
	}
	if health.Status != "ok" {
		t.Fatalf("health status = %q", health.Status)
	}
}

func TestScratchTicketPlaysAndPays(t *testing.T) {
	c := newClient(t)
	c.signIn("scratcher")
	start := c.fund(100_000_000)

	var res struct {
		Outcome struct {
			TierName   string `json:"tier_name"`
			PayoutMsat int64  `json:"payout_msat"`
			Cells      []int  `json:"cells"`
		} `json:"outcome"`
		BalanceMsat int64 `json:"balance_msat"`
	}
	const stake = 1_000_000
	if code := c.do("POST", "/api/scratch/play",
		map[string]any{"ticket_id": "nebula-nine", "stake_msat": stake}, &res); code != 200 {
		t.Fatalf("scratch play returned %d", code)
	}
	if len(res.Outcome.Cells) != 9 {
		t.Fatalf("got %d cells, want 9", len(res.Outcome.Cells))
	}
	want := start - stake + res.Outcome.PayoutMsat
	if res.BalanceMsat != want {
		t.Fatalf("balance = %d, want %d (start %d, stake %d, payout %d)",
			res.BalanceMsat, want, start, stake, res.Outcome.PayoutMsat)
	}
}

func itoa(v int64) string {
	if v == 0 {
		return "0"
	}
	var buf [20]byte
	i := len(buf)
	for v > 0 {
		i--
		buf[i] = byte('0' + v%10)
		v /= 10
	}
	return string(buf[i:])
}