package oidc

import (
	"net/http"
	"sync"
	"time"

	"keycape/internal/domain"
)

const (
	loginCookieName = "kc_login"
	loginSessionTTL = 8 * time.Hour
)

// LoginSession is a KeyCape browser session that records the assurance
// already proven for a user. It is not client-specific: a later high-
// assurance client must still step up if the stored level is too low.
type LoginSession struct {
	ID        string
	Username  string
	Level     domain.AssuranceLevel
	IssuedAt  time.Time
	ExpiresAt time.Time
}

// LoginSessionStore is an in-memory login-session map keyed by cookie value.
type LoginSessionStore struct {
	mu       sync.Mutex
	sessions map[string]*LoginSession
}

// NewLoginSessionStore returns an empty login-session store.
func NewLoginSessionStore() *LoginSessionStore {
	return &LoginSessionStore{sessions: make(map[string]*LoginSession)}
}

// Create stores a session and returns it.
func (s *LoginSessionStore) Create(username string, level domain.AssuranceLevel) *LoginSession {
	if s == nil {
		return nil
	}
	id, err := randomID()
	if err != nil {
		panic("oidc: failed to generate login session id: " + err.Error())
	}
	now := time.Now()
	sess := &LoginSession{
		ID:        id,
		Username:  username,
		Level:     level,
		IssuedAt:  now,
		ExpiresAt: now.Add(loginSessionTTL),
	}
	s.mu.Lock()
	s.sessions[id] = sess
	s.mu.Unlock()
	return sess
}

// Get returns a live session by id.
func (s *LoginSessionStore) Get(id string) (*LoginSession, bool) {
	if s == nil || id == "" {
		return nil, false
	}
	s.mu.Lock()
	sess, ok := s.sessions[id]
	s.mu.Unlock()
	if !ok {
		return nil, false
	}
	if time.Now().After(sess.ExpiresAt) {
		s.Delete(id)
		return nil, false
	}
	return sess, true
}

// Delete removes a session.
func (s *LoginSessionStore) Delete(id string) {
	if s == nil {
		return
	}
	s.mu.Lock()
	delete(s.sessions, id)
	s.mu.Unlock()
}

func (s *LoginSessionStore) fromRequest(r *http.Request) *LoginSession {
	if s == nil || r == nil {
		return nil
	}
	c, err := r.Cookie(loginCookieName)
	if err != nil || c.Value == "" {
		return nil
	}
	sess, ok := s.Get(c.Value)
	if !ok {
		return nil
	}
	return sess
}

func writeLoginCookie(w http.ResponseWriter, sess *LoginSession, secure bool) {
	if sess == nil {
		return
	}
	http.SetCookie(w, &http.Cookie{
		Name:     loginCookieName,
		Value:    sess.ID,
		Path:     "/",
		Expires:  sess.ExpiresAt,
		MaxAge:   int(time.Until(sess.ExpiresAt).Seconds()),
		HttpOnly: true,
		SameSite: http.SameSiteLaxMode,
		Secure:   secure,
	})
}

func clearLoginCookie(w http.ResponseWriter, secure bool) {
	http.SetCookie(w, &http.Cookie{
		Name:     loginCookieName,
		Value:    "",
		Path:     "/",
		MaxAge:   -1,
		HttpOnly: true,
		SameSite: http.SameSiteLaxMode,
		Secure:   secure,
	})
}