package main

import (
	"bufio"
	"bytes"
	"encoding/xml"
	"fmt"
	"io"
	"os"
)

func process(r *bufio.Reader) {
	var (
		intitle       bool
		inarticlemeta bool
		buffer        bytes.Buffer
	)

	dec := xml.NewDecoder(r)
	for {
		token, err := dec.Token()
		if err == io.EOF {
			break
		}
		if err != nil {
			fmt.Fprintf(os.Stderr, "Error when decoding XML file %q\n", err)
			os.Exit(1)
		}
		switch t := token.(type) {
		case xml.StartElement:
			if t.Name.Local == "article-meta" {
				inarticlemeta = true
				continue
			}
			if t.Name.Local == "article-title" && inarticlemeta {
				intitle = true
			}
		case xml.CharData:
			if !intitle || !inarticlemeta {
				continue
			}
			buffer.Write(t)
		case xml.EndElement:
			if t.Name.Local == "article-meta" {
				inarticlemeta = false
				continue
			}
			if t.Name.Local == "article-title" && inarticlemeta {
				intitle = false
				fmt.Printf("article-title: %s\n", buffer.String())
				buffer.Reset()
			}
		}
	}
}

func main() {
	for _, arg := range os.Args[1:] {
		file, err := os.Open(arg)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Error when opening file %q\n", arg)
			os.Exit(1)
		}

		r := bufio.NewReader(file)
		process(r)
		file.Close()
	}
}