moth/src/mothball.go

package main

import (
	"archive/zip"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"time"
)

type Mothball struct {
	zf       *zip.ReadCloser
	filename string
	mtime    time.Time
}

func OpenMothball(filename string) (*Mothball, error) {
	var m Mothball

	m.filename = filename

	err := m.Refresh()
	if err != nil {
		return nil, err
	}

	return &m, nil
}

func (m *Mothball) Close() error {
	return m.zf.Close()
}

func (m *Mothball) Refresh() error {
	info, err := os.Stat(m.filename)
	if err != nil {
		return err
	}
	mtime := info.ModTime()

	if !mtime.After(m.mtime) {
		return nil
	}

	zf, err := zip.OpenReader(m.filename)
	if err != nil {
		return err
	}

	if m.zf != nil {
		m.zf.Close()
	}
	m.zf = zf
	m.mtime = mtime

	return nil
}

func (m *Mothball) Open(filename string) (io.ReadCloser, error) {
	for _, f := range m.zf.File {
		if filename == f.Name {
			ret, err := f.Open()
			return ret, err
		}
	}
	return nil, fmt.Errorf("File not found: %s in %s", filename, m.filename)
}

func (m *Mothball) ReadFile(filename string) ([]byte, error) {
	f, err := m.Open(filename)
	if err != nil {
		return nil, err
	}
	defer f.Close()

	bytes, err := ioutil.ReadAll(f)
	return bytes, err
}