movies/collection.go

package movies

import (
	"encoding/json"
	"io/ioutil"
	"sync"
)

type Collection struct {
	Movies []*Movie

	mutex      sync.RWMutex
	hasChanged bool
}

func Import(filename string) (*Collection, error) {
	b, err := ioutil.ReadFile(filename)
	if err != nil {
		return nil, err
	}

	var c Collection
	if err := json.Unmarshal(b, &c); err != nil {
		return nil, err
	}

	return &c, nil
}

func (c *Collection) Export(filename string) error {
	c.mutex.RLock()
	defer c.mutex.RUnlock()

	b, err := json.Marshal(c)
	if err != nil {
		return err
	}

	err = ioutil.WriteFile(filename, b, 0644)
	if err != nil {
		return err
	}

	c.hasChanged = false
	return nil
}

func (c *Collection) Add(m *Movie) {
	c.mutex.Lock()
	defer c.mutex.Unlock()

	c.Movies = append(c.Movies, m)
	c.hasChanged = true
}

func (c *Collection) HasChanged() bool {
	return c.hasChanged
}