package main

import (
	_url "net/url"
	"strings"
	log "github.com/sirupsen/logrus"
	"regexp"
)

func stripHNPrefix(title string) string {
	title = strings.TrimPrefix(title, "Ask HN:")
	title = strings.TrimPrefix(title, "Show HN:")
	title = strings.TrimPrefix(title, "Tell HN:")
	title = strings.TrimPrefix(title, "Experiment HN:")
	title = strings.TrimPrefix(title, "Launch HN:")

	return strings.TrimSpace(title)
}

/**
 * removes given param from URL
 */
func _removeParam(url, key string) string {
	u, err := _url.Parse(url)
	if err != nil {
		log.Fatal(err)
	}
	q := u.Query()
	q.Del(key)
	u.RawQuery  = q.Encode()
	return u.String()
}

func normalizeUrl(url string) string {
	match, err := regexp.MatchString("^http://", url)
	if err != nil {
		log.Fatal(err)
	}
	if match {
		log.Debug("normalize: ", "http:// ", url)
		r := regexp.MustCompile("^http://")
		url = r.ReplaceAllString(url, "https://")
	}

	// add missing https:// if no scheme
	u, err := _url.Parse(url)
	if err != nil {
		log.Fatal(err)
	}

	if "" == u.Scheme {
		if strings.HasPrefix(url, "/") {
			url = "https:" + url
		} else {
			url = "https://" + url
		}
	}


	match, err = regexp.MatchString("youtube://", url)
	if err != nil {
		log.Fatal(err)
	}
	if match {
		r := regexp.MustCompile("youtube://")
		url = r.ReplaceAllString(url, "https://")
	}

	match, err = regexp.MatchString("youtu.be/", url)
	if err != nil {
		log.Fatal(err)
	}
	if match {
		log.Debug("normalize: ", "youtu.be ", url)

		/**
		 * remove tracking param "si"
		 */
		url = _removeParam(url, "si")
		url = _removeParam(url, "feature")

		u, err := _url.Parse(url)
		if err != nil {
			log.Fatal(err)
		}
		q := u.Query()
		q.Add("v", strings.TrimLeft(u.Path, "/"))

		u.Host = "www.youtube.com"
		u.Path = "watch"

		u.RawQuery = q.Encode()
		url = u.String()
		
		//r := regexp.MustCompile("youtu.be/")
		//url = r.ReplaceAllString(url, "youtube.com/watch?v=")
	}

	match, err = regexp.MatchString("/m.youtube.com/", url)
	if err != nil {
		log.Fatal(err)
	}
	if match {
		log.Debug("normalize: ", "m.youtube.com ", url)

		/**
		 * remove tracking param "si"
		 */
		url = _removeParam(url, "si")
		url = _removeParam(url, "feature")

		r := regexp.MustCompile("/m.youtube.com/")
		url = r.ReplaceAllString(url, "/www.youtube.com/")
	}

	match, err = regexp.MatchString("/m.imdb.com/", url)
	if err != nil {
		log.Fatal(err)
	}
	if match {
		log.Debug("normalize: ", "m.imdb.com ", url)

		/**
		 * remove tracking param "si"
		 */
		url = _removeParam(url, "si")
		url = _removeParam(url, "feature")

		r := regexp.MustCompile("/m.imdb.com/")
		url = r.ReplaceAllString(url, "/www.imdb.com")
	}

	/*
	match, err = regexp.MatchString("m.wikipedia.org", url)
	if err != nil {
		log.Fatal(err)
	}
	if match {
		r := regexp.MustCompile("m.wikipedia.org")
		url = r.ReplaceAllString(url, "wikipedia.org")
	}
	*/

	/**
	 * remove tracking utm_ params
	 */
	url = _removeParam(url, "utm_source")
	url = _removeParam(url, "utm_medium")
	url = _removeParam(url, "utm_campaign")
	url = _removeParam(url, "utm_term")
	url = _removeParam(url, "utm_content")

	u, err = _url.Parse(url)
	if err != nil {
		log.Fatal(err)
	}

	/**
	 * Append www. to normalize URL. exclude relative URLs starting with // since this is not recognized by Go
	 * Screw that, wierd edge case. Someone pasted a
	 */
	if ! strings.HasPrefix(u.Host, "www.") {
		u.Host = "www." + u.Host
	}
	url = u.String()

	return url
}