1
restaurant-search/build/scrape.go
2015-09-18 17:14:48 +09:00

175 lines
3.6 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 (
"log"
"net/url"
"sync"
"github.com/PuerkitoBio/goquery"
)
type feature struct {
value float64
weight float64
}
type review struct {
name string
address string
url string
features map[string]feature
latitude float64
longitude float64
scr scraper
err error
}
type scraper interface {
index(doc *goquery.Document) (string, []string)
review(doc *goquery.Document) (string, string, map[string]feature, error)
decode(address string) (float64, float64, error)
load(url string) (*goquery.Document, error)
}
func makeAbsUrl(ref, base string) (string, error) {
b, err := url.Parse(base)
if err != nil {
return "", err
}
r, err := url.Parse(ref)
if err != nil {
return "", err
}
return b.ResolveReference(r).String(), nil
}
func decodeReviews(in chan review, out chan review, scr scraper) {
for rev := range in {
if rev.err == nil {
rev.latitude, rev.longitude, rev.err = scr.decode(rev.address)
}
out <- rev
}
close(out)
}
func scrapeReview(url string, out chan review, scr scraper, group *sync.WaitGroup) {
defer group.Done()
var (
doc *goquery.Document
rev = review{url: url, scr: scr}
)
if doc, rev.err = scr.load(rev.url); rev.err == nil {
rev.name, rev.address, rev.features, rev.err = scr.review(doc)
}
out <- rev
}
func scrapeIndex(indexUrl string, out chan review, scr scraper) error {
var group sync.WaitGroup
defer func() {
group.Wait()
close(out)
}()
for {
doc, err := scr.load(indexUrl)
if err != nil {
return err
}
nextIndexUrl, reviewUrls := scr.index(doc)
if err != nil {
return err
}
for _, reviewUrl := range reviewUrls {
absUrl, err := makeAbsUrl(reviewUrl, indexUrl)
if err != nil {
return err
}
group.Add(1)
go scrapeReview(absUrl, out, scr, &group)
}
if err != nil {
return err
}
if nextIndexUrl == "" {
break
}
indexUrl, err = makeAbsUrl(nextIndexUrl, indexUrl)
if err != nil {
return err
}
}
return nil
}
func scrape(url string, scr scraper) ([]review, error) {
out := make(chan review, 128)
in := make(chan review, 128)
var (
reviews []review
wg sync.WaitGroup
)
wg.Add(1)
defer wg.Wait()
go func() {
defer wg.Done()
for rev := range out {
if rev.err == nil {
log.Printf("SUCCESS: %s", rev.name)
reviews = append(reviews, rev)
} else {
log.Printf("FAIL: %s", rev.name)
}
}
}()
go decodeReviews(in, out, scr)
err := scrapeIndex(url, in, scr)
return reviews, err
}