package main

import (
	"git.gutmet.org/goutil.git"
	"github.com/fsnotify/fsnotify"
	"golang.org/x/net/html"
	"log"
	"os"
	"path/filepath"
	"strings"
	"time"
)

const (
	NAME     = "ambrowse"
	DIR      = "ambrowse" // inside home directory
	BOOKFILE = "books.yaml"
)

type book struct {
	title       string
	authors     []string
	publisher   string
	isbn10      string
	isbn13      string
	amazonPrice string
}

func (b book) String() string {
	return strings.Join([]string{b.title, strings.Join(b.authors, ", "), b.publisher, b.isbn10, b.isbn13, b.amazonPrice}, "\n")
}

func (b book) yaml() string {
	return "\n---\n\n" +
		"title: \"" + b.title + "\"\n" +
		"authors: [" + strings.Join(b.authors, ", ") + "]\n" +
		"publisher: \"" + b.publisher + "\"\n" +
		"isbn10: " + b.isbn10 + "\n" +
		"isbn13: " + b.isbn13 + "\n" +
		"amazonPrice: \"" + b.amazonPrice + "\"\n"
}

func optFatal(err error) {
	if err != nil {
		log.Fatal(err)
	}
}

func optLog(err error) {
	if err != nil {
		log.Println(err)
	}
}

func readLine(line string) string {
	line = strings.TrimSpace(line)
	parts := strings.Split(line, ":")
	if len(parts) >= 2 {
		return strings.TrimSpace(strings.Join(parts[1:], ":"))
	} else {
		return ""
	}
}

func getDirectory() string {
	home, err := goutil.HomeDir()
	if err != nil {
		log.Fatal("Cannot identify home directory", err)
	}
	dir := filepath.Join(home, DIR)
	err = os.MkdirAll(dir, 0750)
	if err != nil {
		log.Fatal("Cannot create "+dir, err)
	}
	return dir
}

func getAuthors(doc *goutil.HtmlNode) []string {
	authors := make(map[string]interface{})
	authorNodes := doc.GetElementsByClass("contributorNameID")
	authorNodes = append(authorNodes, doc.GetElementsByClass("author")...)
	for _, n := range authorNodes {
		decl := n.GetElementsByClass("a-declarative")
		if len(decl) > 0 {
			authors[decl[0].Text()] = nil
		} else {
			authors[strings.TrimSuffix(n.Text(), ",")] = nil
		}
	}
	result := []string{}
	for k, _ := range authors {
		result = append(result, k)
	}
	return result
}

func setDetails(b *book, doc *goutil.HtmlNode) {
	details := doc.GetElementById("detail-bullets")
	if details == nil {
		details = doc.GetElementById("detail_bullets_id")
	}
	if details != nil {
		tmpcont := details.GetElementsByClass("content")
		if len(tmpcont) > 0 {
			cont := tmpcont[0].FindAll(func(n *goutil.HtmlNode) bool { return n.Type == html.ElementNode && n.Data == "li" })
			for _, c := range cont {
				line := c.Text()
				if strings.Contains(line, "Verlag") || strings.Contains(line, "Publisher") {
					b.publisher = readLine(line)
				} else if strings.Contains(line, "ISBN-10") {
					b.isbn10 = readLine(line)
				} else if strings.Contains(line, "ISBN-13") {
					b.isbn13 = readLine(line)
				}
			}
		}
	}
}

func getPrice(doc *goutil.HtmlNode) string {
	price := doc.GetElementsByClass("a-color-price")
	if len(price) > 0 {
		return strings.TrimSpace(price[0].Text())
	} else {
		return ""
	}
}

func readHTML(filename string) book {
	b := book{}
	log.Println("Reading metadata from " + filename)
	f, err := os.Open(filename)
	optFatal(err)
	tmpdoc, err := html.Parse(f)
	optFatal(err)
	doc := (*goutil.HtmlNode)(tmpdoc)
	title := doc.GetElementById("productTitle")
	b.title = title.Text()
	b.authors = getAuthors(doc)
	setDetails(&b, doc)
	b.amazonPrice = getPrice(doc)
	return b
}

func clean(files []string) {
	time.Sleep(30 * time.Second)
	for _, file := range files {
		os.RemoveAll(file)
	}
}

func digest(dir string, created []string) {
	for _, file := range created {
		if filepath.Ext(file) == ".html" && goutil.PathExists(file) {
			b := readHTML(file)
			if b.title != "" {
				err := goutil.AppendToFile(filepath.Join(dir, BOOKFILE), b.yaml())
				if err != nil {
					log.Println(err)
				}
				goutil.Notify(NAME, b.String())
			}
		}
	}
	go clean(created)
}

func main() {
	dir := getDirectory()
	watcher, err := fsnotify.NewWatcher()
	optFatal(err)
	defer watcher.Close()
	done := make(chan bool)
	go func() {
		created := []string{}
		for {
			select {
			case event, ok := <-watcher.Events:
				if !ok {
					return
				}
				if event.Op&fsnotify.Create == fsnotify.Create && filepath.Base(event.Name) != BOOKFILE {
					created = append(created, event.Name)
				}
			case err, ok := <-watcher.Errors:
				if !ok {
					return
				}
				log.Println("error:", err)
			case <-time.After(1 * time.Second):
				// 1s after last file system event: munch data
				if len(created) > 0 {
					tmpcreated := created
					created = []string{}
					go digest(dir, tmpcreated)
				}
			}

		}
	}()
	err = watcher.Add(dir)
	optFatal(err)
	log.Println(NAME + " is watching " + dir)
	<-done
}