1
restaurant-search/geocache.go
2015-08-15 17:37:34 +09:00

98 lines
2.4 KiB
Go

/*
* Copyright (c) 2015 Alex Yatskov <alex@foosoft.net>
* Author: Alex Yatskov <alex@foosoft.net>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package main
import (
"encoding/json"
"io/ioutil"
"os"
"time"
"github.com/kellydunn/golang-geo"
)
type geoPos struct {
Latitude float64
Longitude float64
}
type geoCache struct {
filename string
data map[string]geoPos
ticker *time.Ticker
coder geo.GoogleGeocoder
}
func newGeoCache(filename string) (*geoCache, error) {
cache := &geoCache{
filename: filename,
data: make(map[string]geoPos),
ticker: time.NewTicker(time.Millisecond * 200),
}
if err := cache.load(); err != nil {
return nil, err
}
return cache, nil
}
func (c *geoCache) load() error {
file, err := os.Open(c.filename)
if os.IsNotExist(err) {
return nil
}
if err != nil {
return err
}
defer file.Close()
return json.NewDecoder(file).Decode(&c.data)
}
func (c *geoCache) save() error {
js, err := json.MarshalIndent(c.data, "", " ")
if err != nil {
return err
}
return ioutil.WriteFile(c.filename, js, 0644)
}
func (c *geoCache) decode(address string) (geoPos, error) {
if pos, ok := c.data[address]; ok {
return pos, nil
}
<-c.ticker.C
point, err := c.coder.Geocode(address)
if err != nil {
return geoPos{}, err
}
pos := geoPos{point.Lat(), point.Lng()}
c.data[address] = pos
return pos, nil
}