package main

import (
	"bytes"
	"errors"
	"gopkg.in/yaml.v2"
	"strings"
	"time"
)

func writeFrontMatter(entry *Entry) string {
	var buff bytes.Buffer
	t := time.Now().Format(time.RFC3339)
	buff.WriteString("---\n")
	if len(entry.title) > 0 {
		buff.WriteString("title: \"" + entry.title + "\"\n")
	}
	buff.WriteString("date: " + t + "\n")
	buff.WriteString("tags:\n")
	for _, tag := range entry.tags {
		buff.WriteString("- " + tag + "\n")
	}
	if len(entry.link) > 0 {
		buff.WriteString("externalURL: " + entry.link + "\n")
	}
	buff.WriteString("indieweb:\n")
	if len(entry.replyLink) > 0 {
		buff.WriteString("  reply:\n    link: " + entry.replyLink + "\n")
		if len(entry.replyTitle) > 0 {
			buff.WriteString("    title: " + entry.replyTitle + "\n")
		}
	}
	buff.WriteString("---\n")
	return buff.String()
}

func WriteHugoPost(entry *Entry) string {
	var buff bytes.Buffer
	buff.WriteString(writeFrontMatter(entry))
	if len(entry.content) > 0 {
		buff.WriteString(entry.content)
	}
	return buff.String()
}

func readFrontMatter(frontmatter string, entry *Entry) (err error) {
	parsedFrontmatter := &struct {
		Title       string
		Date        string
		Lastmod     string
		Tags        []string
		ExternalURL string `yaml:"externalURL"`
		Indieweb    struct {
			Reply struct {
				Link  string
				Title string
			}
		}
	}{}
	err = yaml.Unmarshal([]byte(frontmatter), &parsedFrontmatter)
	if err != nil {
		err = errors.New("failed parsing frontmatter")
	}
	if len(parsedFrontmatter.Title) > 0 {
		entry.title = parsedFrontmatter.Title
	}
	if len(parsedFrontmatter.Date) > 0 {
		entry.date = parsedFrontmatter.Date
	}
	if len(parsedFrontmatter.Lastmod) > 0 {
		entry.lastmod = parsedFrontmatter.Lastmod
	}
	if len(parsedFrontmatter.Tags) > 0 {
		entry.tags = parsedFrontmatter.Tags
	}
	if len(parsedFrontmatter.ExternalURL) > 0 {
		entry.link = parsedFrontmatter.ExternalURL
	}
	if len(parsedFrontmatter.Indieweb.Reply.Link) > 0 {
		entry.replyLink = parsedFrontmatter.Indieweb.Reply.Link
	}
	if len(parsedFrontmatter.Indieweb.Reply.Title) > 0 {
		entry.replyTitle = parsedFrontmatter.Indieweb.Reply.Title
	}
	return
}

func ReadHugoPost(fileContent string) (entry *Entry, err error) {
	parts := strings.Split(fileContent, "---\n")
	if len(parts) != 3 {
		err = errors.New("empty frontmatter or content")
		return
	}
	entry = new(Entry)
	err = readFrontMatter(parts[1], entry)
	if err != nil {
		return
	}
	entry.content = strings.TrimSuffix(parts[2], "\n")
	return
}