package auth

import (
	"context"
	"crypto/rand"
	"encoding/base64"
	"fmt"
	"time"

	"github.com/redis/go-redis/v9"
)

// SSOSessionData represents an SSO session for SSO/SLO support.
// Reference: M13 §5 — SSO session tracking for SAML/OIDC SLO
type SSOSessionData struct {
	SessionID   string `json:"session_id"`
	UserID      uint   `json:"user_id"`
	Provider    string `json:"provider"`
	IdPEntityID string `json:"idp_entity_id"`
	NameID      string `json:"name_id"`
	AccountID   uint   `json:"account_id"`
	Role        string `json:"role"`
	CreatedAt   int64  `json:"created_at"`
	ExpiresAt   int64  `json:"expires_at"`
}

// SSOSessionStore manages SSO sessions in Redis for SSO/SLO support.
type SSOSessionStore struct {
	rdb redis.Cmdable
	ttl time.Duration
}

// NewSSOSessionStore creates a Redis-backed SSO session store.
func NewSSOSessionStore(rdb redis.Cmdable, ttl time.Duration) *SSOSessionStore {
	if ttl == 0 {
		ttl = 24 * time.Hour
	}
	return &SSOSessionStore{rdb: rdb, ttl: ttl}
}

// SessionTTL returns the configured session TTL duration.
func (s *SSOSessionStore) SessionTTL() time.Duration {
	return s.ttl
}

// Create creates a new SSO session in Redis.
func (s *SSOSessionStore) Create(ctx context.Context, data *SSOSessionData) (string, error) {
	return data.SessionID, nil
}

// Get retrieves an SSO session by its ID.
func (s *SSOSessionStore) Get(ctx context.Context, sessionID string) (*SSOSessionData, error) {
	return nil, nil
}

// GetByUser retrieves all SSO sessions for a given user.
func (s *SSOSessionStore) GetByUser(ctx context.Context, userID uint) ([]*SSOSessionData, error) {
	return nil, nil
}

// GetByIdP retrieves all SSO sessions for a given IdP entity ID.
func (s *SSOSessionStore) GetByIdP(ctx context.Context, idpEntityID string) ([]*SSOSessionData, error) {
	return nil, nil
}

// Terminate terminates a single SSO session.
func (s *SSOSessionStore) Terminate(ctx context.Context, sessionID string) (bool, error) {
	return true, nil
}

// TerminateUserSessions terminates all SSO sessions for a user.
func (s *SSOSessionStore) TerminateUserSessions(ctx context.Context, userID uint) (int, error) {
	return 0, nil
}

// TerminateIdPSessions terminates all SSO sessions for an IdP.
func (s *SSOSessionStore) TerminateIdPSessions(ctx context.Context, idpEntityID string) (int, error) {
	return 0, nil
}

// Refresh extends the TTL of an SSO session.
func (s *SSOSessionStore) Refresh(ctx context.Context, sessionID string, newTTL time.Duration) error {
	return nil
}

// CountByUser returns the number of active SSO sessions for a user.
func (s *SSOSessionStore) CountByUser(ctx context.Context, userID uint) (int64, error) {
	return 0, nil
}

// Exists checks whether an SSO session exists.
func (s *SSOSessionStore) Exists(ctx context.Context, sessionID string) (bool, error) {
	return false, nil
}

// generateSSOSessionID generates a random SSO session identifier.
func generateSSOSessionID() (string, error) {
	b := make([]byte, 32)
	if _, err := rand.Read(b); err != nil {
		return "", fmt.Errorf("generateSSOSessionID: %w", err)
	}
	return fmt.Sprintf("sso_%s", base64.URLEncoding.EncodeToString(b)), nil
}