From ad5b38c838338190f47ac656ce615842e0b83667 Mon Sep 17 00:00:00 2001
From: milarin <milaring@proton.me>
Date: Mon, 6 Mar 2023 11:21:19 +0100
Subject: [PATCH] proper error handling

---
 api.go          | 13 ++++++++-----
 errors.go       | 11 +++++++++++
 go.mod          |  1 +
 go.sum          |  2 ++
 novelupdates.go | 11 +++++------
 5 files changed, 27 insertions(+), 11 deletions(-)
 create mode 100644 errors.go

diff --git a/api.go b/api.go
index e953d57..25f9615 100644
--- a/api.go
+++ b/api.go
@@ -9,6 +9,7 @@ import (
 	"strings"
 	"time"
 
+	"git.milar.in/milarin/adverr"
 	"git.milar.in/milarin/slices"
 	"github.com/PuerkitoBio/goquery"
 )
@@ -28,7 +29,7 @@ func NewApi(cookie string) *Api {
 func (api *Api) GetReadingList(ctx context.Context, listIndex int) (*ReadingList, error) {
 	doc, err := api.GetWithCookie(ctx, fmt.Sprintf("https://www.novelupdates.com/reading-list/?list=%d", listIndex))
 	if err != nil {
-		return nil, err
+		return nil, ErrApiRequestFailed.Wrap(err)
 	}
 
 	listID := ReadingListID(doc.Find("#cssmenu ul li.active a").Text())
@@ -78,7 +79,7 @@ func (api *Api) GetReadingList(ctx context.Context, listIndex int) (*ReadingList
 func (api *Api) GetNovelByID(novelID NovelID) (*Novel, error) {
 	doc, err := api.Get(context.Background(), fmt.Sprintf("https://www.novelupdates.com/series/%s/", novelID))
 	if err != nil {
-		return nil, err
+		return nil, ErrApiRequestFailed.Wrap(err)
 	}
 
 	title := doc.Find(".seriestitlenu").Text()
@@ -87,7 +88,7 @@ func (api *Api) GetNovelByID(novelID NovelID) (*Novel, error) {
 
 	associatedNamesHtml, err := doc.Find("#editassociated").Html()
 	if err != nil {
-		return nil, err
+		return nil, ErrApiElementNotFound.Wrap(err, "#editassociated")
 	}
 	associatedNames := strings.Split(strings.TrimSpace(associatedNamesHtml), "<br/>")
 
@@ -142,7 +143,7 @@ func (api *Api) GetChapterEntriesByNovelID(novelID NovelID) *Cursor[NovelChapter
 
 		pageCount, err := strconv.ParseInt(doc.Find(".digg_pagination a:nth-child(5)").Text(), 10, 64)
 		if err != nil {
-			fmt.Fprintln(os.Stderr, err)
+			adverr.Println(ErrApiElementNotFound.Wrap(err, ".digg_pagination a:nth-child(5)"))
 			return
 		}
 
@@ -153,6 +154,7 @@ func (api *Api) GetChapterEntriesByNovelID(novelID NovelID) *Cursor[NovelChapter
 
 			entries, err := api.getChapterEntriesByPageIndex(ctx, novelID, pageIndex)
 			if err != nil {
+				fmt.Fprintln(os.Stderr, err)
 				return
 			}
 
@@ -173,7 +175,7 @@ func (api *Api) GetChapterEntriesByNovelID(novelID NovelID) *Cursor[NovelChapter
 func (api *Api) getChapterEntriesByPageIndex(ctx context.Context, novelID NovelID, pageIndex int) ([]NovelChapterEntry, error) {
 	doc, err := api.Get(ctx, fmt.Sprintf("https://www.novelupdates.com/series/%s/?pg=%d", novelID, pageIndex))
 	if err != nil {
-		return nil, err
+		return nil, ErrApiRequestFailed.Wrap(err)
 	}
 
 	entryElems := doc.Find("#myTable tbody tr")
@@ -187,6 +189,7 @@ func (api *Api) getChapterEntriesByPageIndex(ctx context.Context, novelID NovelI
 
 		date, err := time.Parse("01/02/06", strings.TrimSpace(s.Find("td:first-child").Text()))
 		if err != nil {
+			adverr.Println(ErrApiElementNotFound.Wrap(err, "td:first-child"))
 			return
 		}
 
diff --git a/errors.go b/errors.go
new file mode 100644
index 0000000..2f1a7dd
--- /dev/null
+++ b/errors.go
@@ -0,0 +1,11 @@
+package nuapi
+
+import "git.milar.in/milarin/adverr"
+
+var (
+	ErrNoCookieSet        = adverr.NewErrTmpl("ErrNoCookieSet", "no API cookie set")
+	ErrCurlRequestFailed  = adverr.NewErrTmpl("ErrCurlRequestFailed", "curl request failed for url: '%s'")
+	ErrInvalidGzipData    = adverr.NewErrTmpl("ErrInvalidGzipData", "gzip encoded data expected")
+	ErrApiRequestFailed   = adverr.NewErrTmpl("ErrApiRequestFailed", "Data retrieval from NU failed")
+	ErrApiElementNotFound = adverr.NewErrTmpl("ErrApiElementNotFound", "element not found: '%ss'")
+)
diff --git a/go.mod b/go.mod
index 26d5142..9090927 100644
--- a/go.mod
+++ b/go.mod
@@ -3,6 +3,7 @@ module git.milar.in/milarin/nu-api
 go 1.20
 
 require (
+	git.milar.in/milarin/adverr v1.1.0
 	git.milar.in/milarin/slices v0.0.6
 	github.com/PuerkitoBio/goquery v1.8.1
 )
diff --git a/go.sum b/go.sum
index 6fe43c5..ea996f4 100644
--- a/go.sum
+++ b/go.sum
@@ -1,3 +1,5 @@
+git.milar.in/milarin/adverr v1.1.0 h1:jD9WnOvs40lfMhvqQ7cllOaRJNBMWr1f07/s9jAadp0=
+git.milar.in/milarin/adverr v1.1.0/go.mod h1:joU9sBb7ySyNv4SpTXB0Z4o1mjXsArBw4N27wjgzj9E=
 git.milar.in/milarin/slices v0.0.6 h1:AQoSarZ58WHYol9c6woWJSe8wFpPC2RC4cvIlZpfg9s=
 git.milar.in/milarin/slices v0.0.6/go.mod h1:NOr53AOeur/qscu/FBj3lsFR262PNYBccLYSTCAXRk4=
 github.com/PuerkitoBio/goquery v1.8.1 h1:uQxhNlArOIdbrH1tr0UXwdVFgDcZDrZVdcpygAcwmWM=
diff --git a/novelupdates.go b/novelupdates.go
index 9da214b..0546feb 100644
--- a/novelupdates.go
+++ b/novelupdates.go
@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"compress/gzip"
 	"context"
-	"errors"
 	"fmt"
 	"os/exec"
 
@@ -13,7 +12,7 @@ import (
 
 func (api *Api) GetWithCookie(ctx context.Context, url string) (*goquery.Document, error) {
 	if api.Cookie == "" {
-		return nil, errors.New("no API cookie set")
+		return nil, ErrNoCookieSet.New()
 	}
 
 	curl := exec.CommandContext(ctx, "curl",
@@ -25,12 +24,12 @@ func (api *Api) GetWithCookie(ctx context.Context, url string) (*goquery.Documen
 
 	data, err := curl.Output()
 	if err != nil {
-		return nil, err
+		return nil, ErrCurlRequestFailed.New(err, url)
 	}
 
 	r, err := gzip.NewReader(bytes.NewReader(data))
 	if err != nil {
-		return nil, err
+		return nil, ErrInvalidGzipData.New(err)
 	}
 
 	return goquery.NewDocumentFromReader(r)
@@ -45,12 +44,12 @@ func (api *Api) Get(ctx context.Context, url string) (*goquery.Document, error)
 
 	data, err := curl.Output()
 	if err != nil {
-		return nil, err
+		return nil, ErrCurlRequestFailed.New(err, url)
 	}
 
 	r, err := gzip.NewReader(bytes.NewReader(data))
 	if err != nil {
-		return nil, err
+		return nil, ErrInvalidGzipData.New(err)
 	}
 
 	return goquery.NewDocumentFromReader(r)