63 lines
1.4 KiB
Go
63 lines
1.4 KiB
Go
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// Package geocode resolves street addresses to coordinates via the google geocoding api.
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package geocode
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import (
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"encoding/json"
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"fmt"
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"net/http"
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"net/url"
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"sync"
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)
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type Point struct {
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Lat float64
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Lng float64
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}
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type Client struct {
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key string
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mu sync.Mutex
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cache map[string]Point
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}
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func New(key string) *Client {
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return &Client{key: key, cache: map[string]Point{}}
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}
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func (c *Client) Lookup(address string) (Point, error) {
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c.mu.Lock()
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point, ok := c.cache[address]
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c.mu.Unlock()
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if ok {
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return point, nil
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}
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resp, err := http.Get("https://maps.googleapis.com/maps/api/geocode/json?address=" +
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url.QueryEscape(address) + "&key=" + url.QueryEscape(c.key))
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if err != nil {
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return Point{}, err
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}
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defer resp.Body.Close()
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var parsed struct {
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Status string `json:"status"`
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Results []struct {
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Geometry struct {
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Location struct {
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Lat float64 `json:"lat"`
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Lng float64 `json:"lng"`
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} `json:"location"`
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} `json:"geometry"`
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} `json:"results"`
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}
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if err := json.NewDecoder(resp.Body).Decode(&parsed); err != nil {
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return Point{}, err
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}
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if parsed.Status != "OK" || len(parsed.Results) == 0 {
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return Point{}, fmt.Errorf("geocode %q: %s", address, parsed.Status)
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}
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point = Point{Lat: parsed.Results[0].Geometry.Location.Lat, Lng: parsed.Results[0].Geometry.Location.Lng}
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c.mu.Lock()
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c.cache[address] = point
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c.mu.Unlock()
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return point, nil
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}
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