package main

import (
	"errors"
	"net/http"
	"net/url"
	"strconv"
	"strings"
)

func mustInt(v string, fallback int) int {
	n, err := strconv.Atoi(strings.TrimSpace(v))
	if err != nil {
		return fallback
	}
	return n
}

func mustInt64(v string, fallback int64) int64 {
	n, err := strconv.ParseInt(strings.TrimSpace(v), 10, 64)
	if err != nil {
		return fallback
	}
	return n
}

func parseInt64List(values []string) ([]int64, error) {
	var out []int64
	for _, v := range values {
		id := mustInt64(v, 0)
		if id <= 0 {
			return nil, errors.New("invalid id")
		}
		out = append(out, id)
	}
	return out, nil
}

func placeholders(n int) string {
	parts := make([]string, 0, n)
	for i := 0; i < n; i++ {
		parts = append(parts, "?")
	}
	return strings.Join(parts, ",")
}

func redirectWithMessage(w http.ResponseWriter, r *http.Request, path, key, val string) {
	http.Redirect(w, r, path+"?"+key+"="+url.QueryEscape(val), http.StatusSeeOther)
}