161 lines
3.4 KiB
Go
161 lines
3.4 KiB
Go
/*
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* Copyright (c) 2015 Alex Yatskov <alex@foosoft.net>
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* Author: Alex Yatskov <alex@foosoft.net>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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package main
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import (
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"net/url"
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"sync"
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"github.com/PuerkitoBio/goquery"
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)
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type feature struct {
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value float64
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weight float64
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}
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type review struct {
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name string
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address string
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url string
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features map[string]feature
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latitude float64
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longitude float64
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closestStnName string
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closestStnDist float64
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err error
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}
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type scraper interface {
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index(doc *goquery.Document) (string, []string)
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review(doc *goquery.Document) (string, string, map[string]feature, error)
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decode(address string) (float64, float64, error)
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load(url string) (*goquery.Document, error)
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}
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func makeAbsUrl(ref, base string) (string, error) {
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b, err := url.Parse(base)
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if err != nil {
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return "", err
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}
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r, err := url.Parse(ref)
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if err != nil {
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return "", err
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}
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return b.ResolveReference(r).String(), nil
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}
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func decodeReviews(in chan review, out chan review, scr scraper) {
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for rev, ok := <-in; ok; {
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if rev.err == nil {
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rev.latitude, rev.longitude, rev.err = scr.decode(rev.address)
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}
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out <- rev
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}
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close(out)
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}
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func scrapeReview(url string, out chan review, scr scraper, group *sync.WaitGroup) {
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defer group.Done()
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var (
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doc *goquery.Document
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rev = review{url: url}
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)
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if doc, rev.err = scr.load(rev.url); rev.err == nil {
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rev.name, rev.address, rev.features, rev.err = scr.review(doc)
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}
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out <- rev
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}
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func scrapeIndex(indexUrl string, out chan review, scr scraper) error {
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var group sync.WaitGroup
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defer func() {
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group.Wait()
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close(out)
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}()
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for {
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doc, err := scr.load(indexUrl)
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if err != nil {
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return err
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}
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nextIndexUrl, reviewUrls := scr.index(doc)
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if err != nil {
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return err
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}
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for _, reviewUrl := range reviewUrls {
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absUrl, err := makeAbsUrl(reviewUrl, indexUrl)
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if err != nil {
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return err
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}
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group.Add(1)
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go scrapeReview(absUrl, out, scr, &group)
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}
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if err != nil {
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return err
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}
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if nextIndexUrl == "" {
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break
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}
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indexUrl, err = makeAbsUrl(nextIndexUrl, indexUrl)
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if err != nil {
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return err
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}
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}
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return nil
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}
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func scrape(url string, scr scraper) ([]review, error) {
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out := make(chan review, 128)
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in := make(chan review, 128)
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go decodeReviews(in, out, scr)
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err := scrapeIndex(url, in, scr)
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var reviews []review
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for rev, ok := <-out; ok; {
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reviews = append(reviews, rev)
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}
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return reviews, err
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}
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