package internal

import (
	"net"
	"net/http"
	"time"
)

// NewClient creates http.Client with modified values for typical web scraper
func NewClient() *http.Client {
	return &http.Client{
		Transport: &http.Transport{
			Proxy: http.ProxyFromEnvironment,
			DialContext: (&net.Dialer{
				Timeout:   30 * time.Second,
				KeepAlive: 30 * time.Second,
				DualStack: true,
			}).DialContext,
			MaxIdleConns:          0,    // Default: 100
			MaxIdleConnsPerHost:   1000, // Default: 2
			IdleConnTimeout:       90 * time.Second,
			TLSHandshakeTimeout:   10 * time.Second,
			ExpectContinueTimeout: 1 * time.Second,
		},
		Timeout: time.Second * 180, // Google's timeout
	}
}

// SetDefaultHeader sets header if not exists before
func SetDefaultHeader(header http.Header, key string, value string) http.Header {
	if header.Get(key) == "" {
		header.Set(key, value)
	}
	return header
}