package captiveportal

import (
	"net/http"
	"strings"

	"github.com/pkg/errors"
)

type OS int

const (
	OSUnknown OS = iota
	OSAndroid
	OSApple
	OSWindows
	OSLinux
)

type Matcher interface {
	Match(r *http.Request) (bool, OS, error)
}

type MatchFunc func(r *http.Request) (bool, OS, error)

func (f MatchFunc) Match(r *http.Request) (bool, OS, error) {
	return f(r)
}

func MatchAndroid(r *http.Request) (bool, error) {
	// Samples
	//
	// https://www.google.com/generate_204
	// http://connectivitycheck.gstatic.com/generate_204
	// http://www.google.com/gen_204
	// http://play.googleapis.com/generate_204
	// http://connectivitycheck.gstatic.com/generate_204
	// http://clients3.google.com/generate_204
	// http://g.cn
	matches := strings.Contains(r.URL.Path, "generate_204") ||
		strings.Contains(r.URL.Path, "gen_204") ||
		strings.Contains(r.Host, "g.cn")

	return matches, nil
}

func MatchApple(r *http.Request) (bool, error) {
	// Samples
	//
	// http://www.apple.com/library/test/success.html
	// http://captive.apple.com/hotspot-detect.html
	matches := strings.Contains(r.Host, "www.apple.com") ||
		strings.Contains(r.Host, "captive.apple.com")

	return matches, nil
}

func MatchLinux(r *http.Request) (bool, error) {
	// Samples
	//
	// http://start.ubuntu.com/connectivity-check.html
	// http://nmcheck.gnome.org/check_network_status.txt
	matches := strings.Contains(r.Host, "start.ubuntu.com") ||
		strings.Contains(r.Host, "nmcheck.gnome.org")

	return matches, nil
}

func MatchWindows(r *http.Request) (bool, error) {
	// Samples
	//
	// http://www.msftncsi.com
	// http://www.msftncsi.com/ncsi.txt
	matches := strings.Contains(r.Host, "www.msftncsi.com")

	return matches, nil
}

// nolint: gochecknoglobals
var defaultMatchers = map[OS]func(r *http.Request) (bool, error){
	OSAndroid: MatchAndroid,
	OSApple:   MatchApple,
	OSWindows: MatchWindows,
	OSLinux:   MatchLinux,
}

func DefaultMatch(r *http.Request) (bool, OS, error) {
	for os, match := range defaultMatchers {
		matches, err := match(r)
		if err != nil {
			return false, OSUnknown, errors.WithStack(err)
		}

		if matches {
			return matches, os, nil
		}
	}

	return false, OSUnknown, nil
}