package game

// Login regressions for the off-owner password path: the production entry
// point verifies passwords and hashes new-account passwords on the
// connection goroutine (never the owner), then completes the state
// transition on the owner. The observable login behavior is unchanged.

import (
	"crypto/sha256"
	"encoding/base64"
	"strings"
	"testing"
	"time"

	"thehouseoficarus/internal/net"
	"thehouseoficarus/internal/player"
)

// waitForOutput polls the queued session writer until substr appears or the
// deadline passes.
func waitForOutput(t *testing.T, conn *chanConn, substr string) {
	t.Helper()
	deadline := time.Now().Add(3 * time.Second)
	for !conn.Contains(substr) && time.Now().Before(deadline) {
		time.Sleep(time.Millisecond)
	}
	if !conn.Contains(substr) {
		t.Fatalf("output %q never arrived; got:\n%s", substr, conn.Bytes())
	}
}

// TestLoginThroughServerEntryUsesOffOwnerPathAndUpgradesLegacyHash drives
// the real server entry point (HandleSessionOnOwner) through: legacy-hash
// account creation, a WRONG password attempt, and a correct login that
// rehashes the legacy SHA-256 hash to Argon2id durably.
func TestLoginThroughServerEntryUsesOffOwnerPathAndUpgradesLegacyHash(t *testing.T) {
	h := newHarness(t)
	h.seedAccount("alice")
	h.seedCharacter("alice", "alice")
	acc, err := h.g.AccountStore.LoadAccount("alice")
	if err != nil {
		t.Fatal(err)
	}
	// Downgrade to a legacy salted SHA-256 hash so the login exercises the
	// transparent rehash.
	salt := []byte("0123456789abcdef")
	sum := sha256.Sum256(append(append([]byte{}, salt...), []byte("pw")...))
	acc.PasswordHash = "sha256:" + base64.RawStdEncoding.EncodeToString(salt) + ":" + strings.ToLower(sha256HashHex(sum))
	if err := h.g.AccountStore.SaveAccount(acc); err != nil {
		t.Fatal(err)
	}

	conn := newChanConn()
	sess := &net.Session{Conn: conn}
	sess.SetState(net.StateAccountName)
	sess.StartWriter()
	lines := make(chan string, 8)
	go h.input(sess, lines)

	lines <- "alice"   // existing account → password prompt (echo off)
	lines <- "wrongpw" // rejected, echo restored, back to account name
	waitForOutput(t, conn, "Wrong password.")
	lines <- "alice" // account name again
	lines <- "pw"    // correct password through the off-owner path
	waitForOutput(t, conn, "Welcome back to Vesta, alice.")

	if sess.Account == nil || sess.Account.Name != "alice" || len(sess.Account.Characters) != 1 {
		t.Fatalf("login did not complete: %+v", sess.Account)
	}
	upgraded, err := h.g.AccountStore.LoadAccount("alice")
	if err != nil {
		t.Fatal(err)
	}
	if !strings.HasPrefix(upgraded.PasswordHash, "argon2id:") {
		t.Errorf("legacy hash not upgraded on login: %s", upgraded.PasswordHash[:12])
	}
	if !player.CheckPassword("pw", upgraded.PasswordHash) {
		t.Error("upgraded hash no longer verifies the password")
	}
}

// TestNewAccountThroughServerEntryHashesOffOwner drives account creation
// through the real server entry point.
func TestNewAccountThroughServerEntryHashesOffOwner(t *testing.T) {
	h := newHarness(t)
	conn := newChanConn()
	sess := &net.Session{Conn: conn}
	sess.SetState(net.StateAccountName)
	sess.StartWriter()
	lines := make(chan string, 8)
	go h.input(sess, lines)

	lines <- "newbie" // unknown name → new-account password prompt
	lines <- "hunter2pass"
	lines <- "hunter2pw" // mismatch → restart account entry (Account reset)
	waitForOutput(t, conn, "Passwords do not match.")
	lines <- "newbie" // account name again
	lines <- "hunter2pw"
	lines <- "hunter2pw"
	lines <- "n" // color prompt
	waitForOutput(t, conn, "Welcome back to Vesta, newbie.")

	created, err := h.g.AccountStore.LoadAccount("newbie")
	if err != nil {
		t.Fatal(err)
	}
	if !strings.HasPrefix(created.PasswordHash, "argon2id:") {
		t.Errorf("created account did not hash with Argon2id: %s", created.PasswordHash[:12])
	}
	if !player.CheckPassword("hunter2pw", created.PasswordHash) {
		t.Error("created hash does not verify the password")
	}
}

// sha256HashHex formats like hex.EncodeToString for the legacy hash check.
func sha256HashHex(sum [32]byte) string {
	const hexdigits = "0123456789abcdef"
	out := make([]byte, 64)
	for i, b := range sum {
		out[i*2] = hexdigits[b>>4]
		out[i*2+1] = hexdigits[b&0x0f]
	}
	return string(out)
}