package main

import (
	"fmt"
	"os"
	"sort"
	"strings"
	"text/template"
)

type (
	blogData struct {
		Date        string
		Title       string
		URL         string
		Text        string
		Attachments []string
	}
)

func generateBlog() {
	fmt.Println("Generating blog dir...")
	genBlogDir()
	fmt.Println("Generating blog page...")
	blogDataSlice := generateBlogPage()
	fmt.Println("Generating blog posts...")
	generateBlogPosts(blogDataSlice)
}

func genBlogDir() {
	os.RemoveAll("html/blog")
	err := os.Mkdir("html/blog", 0o755)
	check(err)
}

func fillLinks(content []byte, post blogData) string {
	state := 0 // 1: link text, 2: attachment text, 5 link, 6 attachment
	var parsedCont, linkText strings.Builder
	for i, char := range content {
		switch {
		// no state, not in any links
		case state == 0:
			if char != '{' { // continue if no link is found
				parsedCont.WriteByte(char)
				continue
			}
			state = 3
			continue
		case state == 3:
			// check link type
			switch char {
			case 'l':
				state = 1
				parsedCont.WriteString("<a href=\"")
				continue
			case 'a':
				state = 2
				parsedCont.WriteString("<a href=\"")
				parsedCont.WriteString(
					"/attachments/" + post.Date + " " + post.Title + "/")
				continue
			default:
				fmt.Printf("ERROR: invalid link identifier at i: %d\n", i)
				panic(1)
			}

		// parsing link text
		case state == 1 || state == 2:
			if char == '|' {
				state += 4
				continue
			}
			linkText.WriteByte(char)

		// parsing link
		case state == 5 || state == 6:
			if char != '}' {
				parsedCont.WriteByte(char)
				continue
			}

			parsedCont.WriteString(
				"\">" + linkText.String() + "</a>")
			state = 0
			linkText.Reset()
			continue
		}
	}
	return parsedCont.String()
}

func generateBlogPage() []blogData {
	// open blog dir
	blogDir, err := os.Open("blog")
	if err != nil {
		fmt.Printf("ERROR opening blog dir: %s\n", err)
	}
	defer blogDir.Close()
	// read blog dir list
	postDirList, err := blogDir.Readdirnames(0)
	if err != nil {
		fmt.Printf("ERROR reading blog list: %s\n", err)
	}

	// sort in reverse to show latest post first
	sort.Sort(sort.Reverse(sort.StringSlice(postDirList)))

	var blogDataSlice []blogData
	// separate date and title in struct
	for _, post := range postDirList {
		fmt.Println(post)
		blogDataSlice = append(blogDataSlice, blogData{
			Date:  post[:10],
			Title: post[11:],
			URL: "blog/" +
				strings.ToLower(strings.ReplaceAll(post, " ", "-")),
		})
	}

	// template
	tpl, err := template.ParseFiles("templates/blogposts.gotmpl")
	if err != nil {
		fmt.Printf("ERROR creating template: %s\n", err)
	}

	f, err := os.Create("html/blog.html")
	if err != nil {
		fmt.Printf("ERROR creating html: %s\n", err)
		panic(1)
	}

	err = tpl.ExecuteTemplate(f, "blogposts.gotmpl", blogDataSlice)
	if err != nil {
		fmt.Printf("ERROR executing template: %s\n", err)
	}

	return blogDataSlice
}

func generateBlogPosts(blogDataSlice []blogData) {
	for _, post := range blogDataSlice {
		content, err := os.ReadFile(
			"blog/" + post.Date + " " + post.Title + "/post.txt")
		if err != nil {
			fmt.Printf("ERROR reading post file: %s\n", err)
		}
		post.Text = fillLinks(content, post)
		if post.Text == "" {
			fmt.Printf("ERROR converting links\n")
		}
		post.Text = strings.ReplaceAll(post.Text, "\n", "<br>")

		tpl, err := template.ParseFiles("templates/blogpost.gotmpl")
		if err != nil {
			fmt.Printf("ERROR creating template: %s\n", err)
		}

		f, err := os.Create("html/" + post.URL + ".html")
		if err != nil {
			fmt.Printf("ERROR creating html: %s\n", err)
			panic(1)
		}

		err = tpl.ExecuteTemplate(f, "blogpost.gotmpl", post)
		if err != nil {
			fmt.Printf("ERROR executing template: %s\n", err)
		}
	}
}