From b0ad7dce102d35123bb0092527b7ceea6df8ad86 Mon Sep 17 00:00:00 2001
From: cblgh <cblgh@cblgh.org>
Date: Wed, 30 Mar 2022 15:13:16 +0200
Subject: [PATCH] add custom webring selector for precrawl

---
 README.md          |  3 +++
 crawler/crawler.go | 21 ++++++++++------
 types/types.go     | 13 +++++-----
 util/util.go       | 63 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 87 insertions(+), 13 deletions(-)

diff --git a/README.md b/README.md
index 37255c1..f12b14c 100644
--- a/README.md
+++ b/README.md
@@ -70,6 +70,9 @@ The config file is written in [TOML](https://toml.io/en/).
 name = "Merveilles Webring"
 # used by the precrawl command and linked to in /about route
 url = "https://webring.xxiivv.com"
+# used by the precrawl command to populate the Crawler.Webring file;
+# takes simple html selectors. might be a bit wonky :)
+webringSelector = "li > a[href]:first-of-type"
 port = 10001
 
 [theme]
diff --git a/crawler/crawler.go b/crawler/crawler.go
index 91b1662..d85ec9c 100644
--- a/crawler/crawler.go
+++ b/crawler/crawler.go
@@ -154,6 +154,10 @@ func collectHeadingText(heading string, e *colly.HTMLElement) {
 }
 
 func SetupDefaultProxy(config types.Config) error {
+	// no proxy configured, go back
+	if config.General.Proxy == "" {
+		return nil
+	}
 	proxyURL, err := url.Parse(config.General.Proxy)
 	if err != nil {
 		return err
@@ -165,7 +169,6 @@ func SetupDefaultProxy(config types.Config) error {
 		},
 	}
 
-	//colly.SetHTTPClient(httpClient)
 	http.DefaultClient = httpClient
 	return nil
 }
@@ -176,6 +179,7 @@ func Precrawl(config types.Config) {
 	if err != nil {
 		log.Fatal(err)
 	}
+
 	res, err := http.Get(config.General.URL)
 	util.Check(err)
 	defer res.Body.Close()
@@ -188,11 +192,12 @@ func Precrawl(config types.Config) {
 	util.Check(err)
 
 	items := make([]string, 0)
-	doc.Find("li").Each(func(i int, s *goquery.Selection) {
-		if domain, exists := s.Find("a").Attr("href"); exists {
-			items = append(items, domain)
-		}
-	})
+	s := doc.Find("html")
+	query := config.General.WebringSelector
+	if query == "" {
+    query = "li > a[href]:first-of-type"
+	}
+	util.QuerySelector(query, s, &items)
 
 	BANNED := getBannedDomains(config.Crawler.BannedDomains)
 	for _, item := range items {
@@ -226,7 +231,9 @@ func Crawl(config types.Config) {
 	c := colly.NewCollector(
 		colly.MaxDepth(3),
 	)
-	c.SetProxy(config.General.Proxy)
+	if config.General.Proxy != "" {
+		c.SetProxy(config.General.Proxy)
+	}
 
 	q, _ := queue.New(
 		5, /* threads */
diff --git a/types/types.go b/types/types.go
index bb893c6..3503a5b 100644
--- a/types/types.go
+++ b/types/types.go
@@ -15,12 +15,13 @@ type PageData struct {
 
 type Config struct {
 	General struct {
-		Name        string `json:name`
-		Tagline     string `json:tagline`
-		Placeholder string `json:placeholder`
-		URL         string `json:url`
-		Port        int    `json:port`
-		Proxy       string `json:proxy`
+		Name            string `json:name`
+		Tagline         string `json:tagline`
+		Placeholder     string `json:placeholder`
+		URL             string `json:url`
+		WebringSelector string `json:"webringSelector"`
+		Port            int    `json:port`
+		Proxy           string `json:proxy`
 	} `json:general`
 	Theme struct {
 		Foreground string `json:"foreground"`
diff --git a/util/util.go b/util/util.go
index fd34ac1..263871d 100644
--- a/util/util.go
+++ b/util/util.go
@@ -4,10 +4,12 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"github.com/PuerkitoBio/goquery"
 	"io/ioutil"
 	"log"
 	"net"
 	"os"
+	"regexp"
 	"strings"
 
 	"lieu/types"
@@ -30,6 +32,66 @@ func Check(err error) {
 	}
 }
 
+// document.querySelectorAll-type functionality. limited functionality as of now (no classes or id support atm, i think!!)
+func QuerySelector(query string, current *goquery.Selection, results *[]string) {
+	var op, operand string
+
+	attrPattern := regexp.MustCompile(`(\w+)\[(\w+)\](.+)?`)
+	attrValuePattern := regexp.MustCompile(`\[(\w+)\]`)
+
+	if len(query) == 0 {
+		return
+	}
+
+	fields := strings.Fields(query)
+	part := fields[0]
+	query = strings.Join(fields[1:], " ")
+	if part == ">" {
+		op = "subchild"
+	} else if attrPattern.MatchString(part) {
+		op = "element"
+		matches := attrPattern.FindStringSubmatch(part)
+		operand = matches[1]
+		var optional string
+		if len(matches) == 4 {
+			optional = matches[3]
+		}
+		query = strings.TrimSpace(fmt.Sprintf("[%s]%s %s", matches[2], optional, query))
+	} else if attrValuePattern.MatchString(part) {
+		op = "attr"
+		operand = attrValuePattern.FindStringSubmatch(part)[1]
+	} else if len(query) == 0 {
+		op = "final"
+	} else {
+		op = "element"
+		operand = part
+	}
+
+	switch op {
+	case "element": // e.g. [el]; bla > [el]; but also [el] > bla
+		current = current.Find(operand)
+		if strings.HasSuffix(query, "first-of-type") {
+			break
+		}
+		fallthrough
+	case "subchild": // [preceding] > [future]
+		// recurse querySelector on all [preceding] element types
+		current.Each(func(j int, s *goquery.Selection) {
+			QuerySelector(query, s, results)
+		})
+		return
+	case "attr": // x[attr]
+		// extract the attribute
+		if str, exists := current.Attr(operand); exists {
+			*results = append(*results, str)
+		}
+		return
+	case "final": // no more in query, and we did not end on an attr: get text
+		*results = append(*results, current.Text())
+	}
+	QuerySelector(query, current, results)
+}
+
 func DatabaseDoesNotExist(filepath string) {
 	fmt.Printf("lieu: database %s does not exist\n", filepath)
 	fmt.Println("lieu: try running `lieu ingest` if you have already crawled source data")
@@ -104,6 +166,7 @@ func WriteMockConfig() {
 name = "Sweet Webring"
 # used by the precrawl command and linked to in /about route
 url = "https://example.com/"
+webringSelector = "li > a"
 port = 10001
 
 [theme]