mirror of https://github.com/perkeep/perkeep.git
117 lines
2.9 KiB
Go
117 lines
2.9 KiB
Go
/*
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Copyright 2013 The Camlistore Authors
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// Package geocode handles mapping user-entered locations into lat/long polygons.
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package geocode
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import (
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"encoding/json"
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"io"
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"log"
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"net/url"
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"sync"
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"camlistore.org/pkg/context"
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"camlistore.org/pkg/httputil"
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"camlistore.org/pkg/singleflight"
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)
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type LatLong struct {
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Lat float64 `json:"lat"`
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Long float64 `json:"lng"`
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}
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type Rect struct {
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NorthEast LatLong `json:"northeast"`
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SouthWest LatLong `json:"southwest"`
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}
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var (
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mu sync.RWMutex
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cache = map[string][]Rect{}
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sf singleflight.Group
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)
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// Lookup returns rectangles for the given address. Currently the only
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// implementation is the Google geocoding service.
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func Lookup(ctx *context.Context, address string) ([]Rect, error) {
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mu.RLock()
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rects, ok := cache[address]
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mu.RUnlock()
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if ok {
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return rects, nil
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}
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rectsi, err := sf.Do(address, func() (interface{}, error) {
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// TODO: static data files from OpenStreetMap, Wikipedia, etc?
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urlStr := "https://maps.googleapis.com/maps/api/geocode/json?address=" + url.QueryEscape(address) + "&sensor=false"
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res, err := ctx.HTTPClient().Get(urlStr)
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if err != nil {
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return nil, err
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}
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defer httputil.CloseBody(res.Body)
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rects, err := decodeGoogleResponse(res.Body)
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log.Printf("Google geocode lookup (%q) = %#v, %v", address, rects, err)
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if err == nil {
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mu.Lock()
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cache[address] = rects
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mu.Unlock()
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}
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return rects, err
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})
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if err != nil {
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return nil, err
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}
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return rectsi.([]Rect), nil
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}
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type googleResTop struct {
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Results []*googleResult `json:"results"`
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}
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type googleResult struct {
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Geometry *googleGeometry `json:"geometry"`
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}
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type googleGeometry struct {
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Bounds *Rect `json:"bounds"`
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Viewport *Rect `json:"viewport"`
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}
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func decodeGoogleResponse(r io.Reader) (rects []Rect, err error) {
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var resTop googleResTop
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if err := json.NewDecoder(r).Decode(&resTop); err != nil {
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return nil, err
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}
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for _, res := range resTop.Results {
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if res.Geometry != nil && res.Geometry.Bounds != nil {
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r := res.Geometry.Bounds
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if r.NorthEast.Lat == 90 && r.NorthEast.Long == 180 &&
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r.SouthWest.Lat == -90 && r.SouthWest.Long == -180 {
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// Google sometimes returns a "whole world" rect for large addresses (like "USA")
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// so instead use the viewport in that case.
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if res.Geometry.Viewport != nil {
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rects = append(rects, *res.Geometry.Viewport)
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}
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} else {
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rects = append(rects, *r)
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}
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}
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}
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return
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}
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