package db

import (
	"context"
	"crypto/rand"
	"encoding/hex"
	"os"
	"strconv"
	"time"

	"github.com/jackc/pgx/v5"
)

func getDemoDuration() time.Duration {
	if mins := os.Getenv("DEMO_DURATION_MINUTES"); mins != "" {
		if m, err := strconv.Atoi(mins); err == nil && m > 0 {
			return time.Duration(m) * time.Minute
		}
	}
	if os.Getenv("ENV") != "prod" {
		return 100 * 365 * 24 * time.Hour // infinite in local/dev
	}
	return 15 * time.Minute
}

func (db *DB) GetDemoBySubdomain(ctx context.Context, subdomain string) (*Demo, error) {
	var d Demo
	err := db.pool.QueryRow(ctx,
		`SELECT id, subdomain, expires_at FROM demos WHERE subdomain = $1 AND expires_at > NOW()`,
		subdomain).Scan(&d.ID, &d.Subdomain, &d.ExpiresAt)
	if err == pgx.ErrNoRows {
		return nil, nil
	}
	return &d, err
}

func (db *DB) GetDemoByID(ctx context.Context, id string) (*Demo, error) {
	var d Demo
	err := db.pool.QueryRow(ctx,
		`SELECT id, subdomain, expires_at FROM demos WHERE id = $1 AND expires_at > NOW()`,
		id).Scan(&d.ID, &d.Subdomain, &d.ExpiresAt)
	if err == pgx.ErrNoRows {
		return nil, nil
	}
	return &d, err
}

func (db *DB) CreateDemo(ctx context.Context) (*Demo, error) {
	subdomain := "demo-" + randomHex(4)
	expiresAt := time.Now().Add(getDemoDuration())

	var d Demo
	err := db.pool.QueryRow(ctx,
		`INSERT INTO demos (subdomain, expires_at) VALUES ($1, $2) RETURNING id, subdomain, expires_at`,
		subdomain, expiresAt).Scan(&d.ID, &d.Subdomain, &d.ExpiresAt)
	if err != nil {
		return nil, err
	}
	return &d, nil
}

type ExpiredDemo struct {
	ID        string
	Subdomain string
}

func (db *DB) CleanupExpiredDemos(ctx context.Context) ([]ExpiredDemo, error) {
	rows, err := db.pool.Query(ctx,
		`DELETE FROM demos WHERE expires_at < NOW() RETURNING id, subdomain`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var demos []ExpiredDemo
	for rows.Next() {
		var d ExpiredDemo
		if err := rows.Scan(&d.ID, &d.Subdomain); err != nil {
			return nil, err
		}
		demos = append(demos, d)
	}
	return demos, rows.Err()
}

func (db *DB) ListActiveDemos(ctx context.Context) ([]Demo, error) {
	rows, err := db.pool.Query(ctx,
		`SELECT id, subdomain, expires_at FROM demos WHERE expires_at > NOW()`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var demos []Demo
	for rows.Next() {
		var d Demo
		if err := rows.Scan(&d.ID, &d.Subdomain, &d.ExpiresAt); err != nil {
			return nil, err
		}
		demos = append(demos, d)
	}
	return demos, rows.Err()
}

func randomHex(n int) string {
	b := make([]byte, n)
	rand.Read(b)
	return hex.EncodeToString(b)
}