package web

import (
	"bytes"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"io"
	"log"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"testing"
	"time"

	"gitea.dooplex.hu/admin/felhom-controller/internal/config"
	"gitea.dooplex.hu/admin/felhom-controller/internal/settings"
)

// R-35 (D4, operator ruling 2026-10-08): a dashboard sign-in survives the controller's own restart, and the disk holds
// only a fingerprint of each session. Every test builds its servers with NewServer — the call cmd/controller/main.go
// makes — so the load is pinned on the production constructor, not on a helper a test calls by hand.
//
// RED-PROOF (seen 2026-10-08): with loadSessions and saveSessionsLocked reduced to no-ops (today's in-memory-only map),
// TestR35_RestartKeepsSession and TestR35_FileHoldsNoToken fail ("restart: the old cookie no longer signs in";
// "no sessions file written"), and the invalidate/logout/expired cases pass vacuously — which is why the restart
// case is the positive control for each of them: they assert the SAME cookie worked before they assert it stopped.

func newR35Server(t *testing.T, dir string) *Server {
	t.Helper()
	lg := log.New(io.Discard, "", 0)
	sett, err := settings.Load(filepath.Join(dir, "settings.json"), lg)
	if err != nil {
		t.Fatalf("settings: %v", err)
	}
	cfg := &config.Config{}
	cfg.Paths.DataDir = dir
	s := NewServer(cfg, nil, nil, nil, nil, sett, nil, nil, nil, lg, "test")
	t.Cleanup(s.Close)
	return s
}

func TestR35_RestartKeepsSession(t *testing.T) {
	dir := t.TempDir()
	s1 := newR35Server(t, dir)
	tok := s1.createSession()
	csrf := s1.csrfTokenForSession(tok)
	if !s1.isValidSession(tok) || csrf == "" {
		t.Fatal("setup: a fresh session must be valid on the server that made it")
	}
	s1.Close()

	s2 := newR35Server(t, dir) // the restart
	if !s2.isValidSession(tok) {
		t.Fatal("restart: the old cookie no longer signs in")
	}
	if got := s2.csrfTokenForSession(tok); got != csrf {
		t.Fatalf("restart: CSRF token changed (%d chars, want the same %d) — every open page's forms would 403", len(got), len(csrf))
	}
	if s2.isValidSession(tok + "0") {
		t.Fatal("a cookie that was never issued must not sign in")
	}
}

func TestR35_FileHoldsNoToken(t *testing.T) {
	dir := t.TempDir()
	s := newR35Server(t, dir)
	tok := s.createSession()
	b, err := os.ReadFile(filepath.Join(dir, sessionsFileName))
	if err != nil {
		t.Fatalf("no sessions file written: %v", err)
	}
	if bytes.Contains(b, []byte(tok)) {
		t.Fatal("the sessions file holds the cookie value — a stolen archive would sign in")
	}
	sum := sha256.Sum256([]byte(tok))
	if !bytes.Contains(b, []byte(hex.EncodeToString(sum[:]))) {
		t.Fatal("the sessions file does not hold the session's fingerprint (positive control)")
	}
	fi, err := os.Stat(filepath.Join(dir, sessionsFileName))
	if err != nil {
		t.Fatal(err)
	}
	if fi.Mode().Perm() != 0o600 {
		t.Fatalf("sessions file mode %o, want 600", fi.Mode().Perm())
	}

	// The file ALONE cannot sign in: presenting the fingerprint itself as the cookie is rejected on a restarted server.
	s.Close()
	s2 := newR35Server(t, dir)
	if s2.isValidSession(hex.EncodeToString(sum[:])) {
		t.Fatal("the fingerprint read from disk signs in as a cookie")
	}
	if !s2.isValidSession(tok) {
		t.Fatal("positive control: the real cookie must still sign in after the restart")
	}
}

func TestR35_InvalidateAllEndsSessionAcrossRestart(t *testing.T) {
	dir := t.TempDir()
	s1 := newR35Server(t, dir)
	tok := s1.createSession()
	s1.Close()
	s2 := newR35Server(t, dir)
	if !s2.isValidSession(tok) {
		t.Fatal("setup: the session must survive one restart first")
	}
	s2.invalidateAllSessions() // the password change and the claim reset call this
	s2.Close()
	s3 := newR35Server(t, dir)
	if s3.isValidSession(tok) {
		t.Fatal("after a password change the old cookie signs in again after a restart")
	}
}

func TestR35_LogoutEndsSessionAcrossRestart(t *testing.T) {
	dir := t.TempDir()
	s1 := newR35Server(t, dir)
	tok := s1.createSession()
	keep := s1.createSession()
	s1.Close()
	s2 := newR35Server(t, dir)
	if !s2.isValidSession(tok) {
		t.Fatal("setup: the session must survive one restart first")
	}
	req := httptest.NewRequest(http.MethodPost, "/logout", nil)
	req.AddCookie(&http.Cookie{Name: sessionCookieName, Value: tok})
	s2.handleLogout(httptest.NewRecorder(), req)
	if s2.isValidSession(tok) {
		t.Fatal("logout: the session is still valid in the same process")
	}
	s2.Close()
	s3 := newR35Server(t, dir)
	if s3.isValidSession(tok) {
		t.Fatal("logout: the signed-out cookie signs in again after a restart")
	}
	if !s3.isValidSession(keep) {
		t.Fatal("logout of one browser ended another browser's session")
	}
}

func TestR35_ExpiredRowNotLoaded(t *testing.T) {
	dir := t.TempDir()
	s1 := newR35Server(t, dir)
	live := s1.createSession()
	old := s1.createSession()
	// Age one session past its expiry, as 7 days would — through the map the server owns, then persisted.
	s1.sessionsMu.Lock()
	s1.sessions[sessionFingerprint(old)].expiresAt = time.Now().Add(-time.Minute)
	_ = s1.saveSessionsLocked()
	s1.sessionsMu.Unlock()
	s1.Close()

	var f sessionsFile
	b, _ := os.ReadFile(filepath.Join(dir, sessionsFileName))
	if err := json.Unmarshal(b, &f); err != nil {
		t.Fatalf("sessions file: %v", err)
	}
	if len(f.Sessions) != 1 {
		t.Fatalf("an expired row was written to disk: %d rows, want 1", len(f.Sessions))
	}

	s2 := newR35Server(t, dir)
	if s2.isValidSession(old) {
		t.Fatal("an expired session signs in after a restart")
	}
	if !s2.isValidSession(live) {
		t.Fatal("positive control: the live session must survive")
	}
	s2.sessionsMu.RLock()
	n := len(s2.sessions)
	s2.sessionsMu.RUnlock()
	if n != 1 {
		t.Fatalf("loaded %d sessions, want 1", n)
	}
}

// A corrupt or foreign file never stops the controller and never signs anyone in.
func TestR35_CorruptFileStartsEmpty(t *testing.T) {
	dir := t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, sessionsFileName), []byte("{not json"), 0o600); err != nil {
		t.Fatal(err)
	}
	s := newR35Server(t, dir)
	s.sessionsMu.RLock()
	n := len(s.sessions)
	s.sessionsMu.RUnlock()
	if n != 0 {
		t.Fatalf("a corrupt file loaded %d sessions", n)
	}
	tok := s.createSession() // and the next save repairs the file
	s.Close()
	if !newR35Server(t, dir).isValidSession(tok) {
		t.Fatal("after a corrupt file, a new session must persist again")
	}
}