package auth

import (
	"context"
	"crypto/rand"
	"encoding/hex"
	"encoding/json"
	"time"

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

const sessionTTL = 24 * time.Hour
const sessionCookieName = "km_session"
const sessionPrefix = "km:session:"
const statePrefix = "km:state:"

type Session struct {
	UserID string `json:"user_id"`
	Email  string `json:"email"`
	Name   string `json:"name"`
}

var rdb *redis.Client

func InitRedis(addr string) error {
	rdb = redis.NewClient(&redis.Options{Addr: addr})
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	return rdb.Ping(ctx).Err()
}

func randomHex(n int) (string, error) {
	b := make([]byte, n)
	if _, err := rand.Read(b); err != nil {
		return "", err
	}
	return hex.EncodeToString(b), nil
}

func SaveSession(ctx context.Context, sess *Session) (string, error) {
	id, err := randomHex(32)
	if err != nil {
		return "", err
	}
	data, err := json.Marshal(sess)
	if err != nil {
		return "", err
	}
	if err := rdb.Set(ctx, sessionPrefix+id, data, sessionTTL).Err(); err != nil {
		return "", err
	}
	return id, nil
}

func GetSession(ctx context.Context, id string) (*Session, error) {
	data, err := rdb.Get(ctx, sessionPrefix+id).Bytes()
	if err != nil {
		return nil, err
	}
	var sess Session
	if err := json.Unmarshal(data, &sess); err != nil {
		return nil, err
	}
	return &sess, nil
}

func DeleteSession(ctx context.Context, id string) error {
	return rdb.Del(ctx, sessionPrefix+id).Err()
}

func SaveState(ctx context.Context, state string) error {
	return rdb.Set(ctx, statePrefix+state, "1", 10*time.Minute).Err()
}

func ConsumeState(ctx context.Context, state string) bool {
	n, err := rdb.Del(ctx, statePrefix+state).Result()
	return err == nil && n > 0
}