package main

import (
	"fmt"
	"golang.org/x/net/html"
	"html/template"
	"io/ioutil"
	"os"
	"path/filepath"
	"strings"
	"time"
)

//Post : Is exported
type Post struct {
	Date       time.Time
	NormalDate string
	Title      string
	URLTitle   string
	Content    template.HTML
}

const htmlDateLayout = "2006-01-02"
const normalDateLayout = "02 Jan 2006"

var modTime time.Time
var PostsCollection []Post

func NewPostsCollection() {
	verifyFolderModification()
	initializeCollection()
	go acquirePosts(100)
}

func initializeCollection() {
	PostsCollection = nil
	filepath.Walk("./posts", newPost)
	PostsCollection = reversePosts()
}

func acquirePosts(duration time.Duration) {
	for {
		if verifyFolderModification() == true {
			initializeCollection()
			PostsCollection = reversePosts()
		}
		time.Sleep(duration * time.Second)
	}
}

func verifyFolderModification() bool {
	f, err := os.Open("./posts")
	if err != nil {
		fmt.Println("file-error here: \n", f)
		f.Close()
		return false
	}
	info, err := f.Stat()
	if err != nil {
		fmt.Println("info here: \n", info)
		f.Close()
		return false
	}
	_modTime := info.ModTime()
	if modTime != _modTime {
		modTime = _modTime
		f.Close()
		return true
	}
	f.Close()
	return false
}

func newPost(path string, f os.FileInfo, err error) error {
	content, err := ioutil.ReadFile(path)
	if err != nil {
		fmt.Println(err)
		return nil
	}

	title := strings.Replace(path, "posts/", "", -1)
	if !strings.Contains(title, ".html") {
		return nil
	}
	title = strings.Replace(title, ".html", "", -1)
	s := string(content)
	doc, _ := html.Parse(strings.NewReader(s))
	dateParsed := getDate(doc)
	dateFormatted := dateParsed.Format(normalDateLayout)
	var p = Post{
		dateParsed,
		dateFormatted,
		title,
		strings.Replace(title, " ", "-", -1),
		template.HTML(string(content[:len(content)])),
	}

	PostsCollection = insertPostAccordingToDate(p, PostsCollection)
	return nil
}

func getDate(n *html.Node) time.Time {

	var zero, d, t time.Time

	if n.Type == html.ElementNode && n.Data == "time" {
		for _, a := range n.Attr {
			if a.Key == "datetime" {
				t, _ = time.Parse(htmlDateLayout, a.Val)
				return t
			}
		}
	}

	for c := n.FirstChild; c != nil; c = c.NextSibling {
		d = getDate(c)
		if d != zero {
			return d
		}
	}

	return t
}

func reversePosts() []Post {
	length := len(PostsCollection)
	s := make([]Post, length)
	for i := 0; i < length; i++ {
		s[i] = PostsCollection[length-(i+1)]
	}
	return s
}

func getNewestPosts(numberOfPosts int) []Post {
	var posts []Post
	l := len(PostsCollection)
	for i := l - 1; i >= l-numberOfPosts; i-- {
		posts = append(posts, PostsCollection[i])
	}
	return posts
}

func getPostByURLTitle(title string) Post {
	for _, post := range PostsCollection {
		if post.URLTitle == title {
			return post
		}
	}
	return Post{}
}

func insertPostAccordingToDate(post Post, arr []Post) []Post {
	for i, p := range arr {
		if p.Date.After(post.Date) {
			s := make([]Post, len(arr)+1, cap(arr)+1)
			copy(s[:], arr[:])     //make a copy of the slice
			copy(s[i+1:], arr[i:]) //move the upper part of the slice ahead, creating a hole
			s[i] = post            //insert new element into hole
			return s
		}
	}
	PostsCollection = append(PostsCollection, post)
	return PostsCollection
}