package main

import (
	"io"
	"log"
	"net/http"
	"os"
	"regexp"
	"rss/bbclearn"
	"strings"
	"time"
)

var zhihuReg = regexp.MustCompile(`(?is:(<item>(.*?)</item>))`)
var date = regexp.MustCompile(`<pubDate>(.*)</pubDate>`)

func fetch(u string, fn ...func(s string) string) string {
	res, err := http.Get(u)
	if err != nil {
		return ""
	}
	s, err := io.ReadAll(res.Body)
	if err != nil {
		return ""
	}
	html := string(s)
	for _, f := range fn {
		html = f(html)
	}
	return html
}

func dayLimit(today, forwardDay int, s string) string {
	da := date.FindStringSubmatch(s)
	if len(da) <= 1 {
		return s
	}
	t, err := time.Parse(time.RFC1123Z, da[1])
	if err != nil {
		return s
	}
	if today-forwardDay > t.Day() {
		return ""
	}
	return s
}

func filterItem(html string, today, recentDay int) string {
	return zhihuReg.ReplaceAllStringFunc(html, func(s string) string {
		return dayLimit(today, recentDay, s)
	})
}

func penti(w http.ResponseWriter, req *http.Request) {
	io.WriteString(w, fetch("https://feedx.best/rss/pentitugua.xml", func(s string) string {
		return strings.ReplaceAll(s, "www.dapenti.com:99", "imgc.1see.org")
	}))
}

func zhihuDaily(w http.ResponseWriter, req *http.Request) {
	io.WriteString(w, fetch("https://feedx.best/rss/zhihudaily.xml", func(s string) string {
		return filterItem(s, time.Now().Day(), 1)
	}))
}

func tjxz(w http.ResponseWriter, r *http.Request) {

	io.WriteString(w, fetch("https://feedx.best/rss/tjxz.xml", func(s string) string {
		return filterItem(s, time.Now().Day(), 0)
	}))
}
func bbcLearn(w http.ResponseWriter, _ *http.Request) {
	io.WriteString(w, fetch("https://www.bbc.co.uk/learningenglish/chinese", func(s string) string {
		return bbclearn.LearnParse(s, 1)
	}))
}

func theNewYorker(w http.ResponseWriter, r *http.Request) {
	io.WriteString(w, fetch("https://feedx.best/rss/newyorker.xml", func(s string) string {
		return filterItem(s, time.Now().Day(), 1)
	}))
}

func voaLearnEnglish(w http.ResponseWriter, r *http.Request) {
	io.WriteString(w, fetch("https://feedx.best/rss/voalearningenglish.xml", func(s string) string {
		return filterItem(s, time.Now().Day(), 1)
	}))
}

func main() {
	port := os.Getenv("port")
	if port == "" {
		port = ":80"
	}
	time.Local = time.FixedZone("CST", 3600*8)
	http.HandleFunc("/pentitugua", penti)                //喷嚏图挂
	http.HandleFunc("/zhihuDaily", zhihuDaily)           //知乎日报
	http.HandleFunc("/tjxz", tjxz)                       //田间小站
	http.HandleFunc("/bbcLearn", bbcLearn)               //bbc 英语学习
	http.HandleFunc("/theNewYorker", theNewYorker)       //纽约客
	http.HandleFunc("/voaLearnEnglish", voaLearnEnglish) //VOA Learning English
	log.Fatal(http.ListenAndServe(port, nil))
}