1 files changed, 259 insertions, 0 deletions
diff --git a/cmd/rescribe/gbook.go b/cmd/rescribe/gbook.go
new file mode 100644
index 0000000..a011181
--- /dev/null
+++ b/cmd/rescribe/gbook.go
@@ -0,0 +1,259 @@
+// Copyright 2022 Nick White.
+// Use of this source code is governed by the GPLv3
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"os/exec"
+	"path"
+	"regexp"
+	"strings"
+	"unicode"
+
+	"rescribe.xyz/bookpipeline/internal/pipeline"
+)
+
+const maxPartLength = 48
+
+// formatAuthors formats a list of authors by just selecting
+// the first one listed, and returning the uppercased final
+// name.
+func formatAuthors(authors []string) string {
+	if len(authors) == 0 {
+		return ""
+	}
+
+	s := authors[0]
+
+	parts := strings.Fields(s)
+	if len(parts) > 1 {
+		s = parts[len(parts)-1]
+	}
+
+	s = strings.ToUpper(s)
+
+	if len(s) > maxPartLength {
+		// truncate to maxPartLength
+		m := fmt.Sprintf("%%.%ds", maxPartLength)
+		s = fmt.Sprintf(m, s)
+	}
+
+	s = strings.Map(stripNonLetters, s)
+
+	return s
+}
+
+// mapTitle is a function for strings.Map to strip out
+// unwanted characters from the title.
+func stripNonLetters(r rune) rune {
+	if !unicode.IsLetter(r) {
+		return -1
+	}
+	return r
+}
+
+// formatTitle formats a title to our preferences, notably
+// by stripping spaces and punctuation characters.
+func formatTitle(title string) string {
+	s := strings.Map(stripNonLetters, title)
+	if len(s) > maxPartLength {
+		// truncate to maxPartLength
+		m := fmt.Sprintf("%%.%ds", maxPartLength)
+		s = fmt.Sprintf(m, s)
+	}
+	return s
+}
+
+// getMetadata queries Google Books for metadata we care about
+// and returns it formatted as we need it.
+func getMetadata(id string) (string, string, string, error) {
+	var author, title, year string
+	url := fmt.Sprintf("https://www.googleapis.com/books/v1/volumes/%s", id)
+
+	// designed to be unmarshalled by encoding/json's Unmarshal()
+	type bookInfo struct {
+		VolumeInfo struct {
+			Title         string
+			Authors       []string
+			PublishedDate string
+		}
+	}
+
+	resp, err := http.Get(url)
+	if err != nil {
+		return author, title, year, fmt.Errorf("Error downloading metadata %s: %v", url, err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return author, title, year, fmt.Errorf("Error downloading metadata %s: %v", url, err)
+	}
+
+	b, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return author, title, year, fmt.Errorf("Error reading metadata %s: %v", url, err)
+	}
+
+	v := bookInfo{}
+	err = json.Unmarshal(b, &v)
+	if err != nil {
+		return author, title, year, fmt.Errorf("Error parsing metadata %s: %v", url, err)
+	}
+
+	author = formatAuthors(v.VolumeInfo.Authors)
+	title = formatTitle(v.VolumeInfo.Title)
+	year = v.VolumeInfo.PublishedDate
+
+	return author, title, year, nil
+}
+
+// moveFile just copies a file to the destination without
+// using os.Rename, as that can fail if crossing filesystem
+// boundaries
+func moveFile(from string, to string) error {
+	ffrom, err := os.Open(from)
+	if err != nil {
+		return err
+	}
+	defer ffrom.Close()
+
+	fto, err := os.Create(to)
+	if err != nil {
+		return err
+	}
+	defer fto.Close()
+
+	_, err = io.Copy(fto, ffrom)
+	if err != nil {
+		return err
+	}
+
+	ffrom.Close()
+	err = os.Remove(from)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// getGoogleBook downloads all images of a book to a directory
+// named YEAR_AUTHORSURNAME_Title_bookid inside basedir, returning
+// the directory path
+func getGoogleBook(ctx context.Context, gbookcmd string, id string, basedir string) (string, error) {
+	author, title, year, err := getMetadata(id)
+	if err != nil {
+		return "", err
+	}
+
+	tmpdir, err := ioutil.TempDir("", "bookpipeline")
+	if err != nil {
+		return "", fmt.Errorf("Error setting up temporary directory: %v", err)
+	}
+
+	cmd := exec.CommandContext(ctx, gbookcmd, id)
+	pipeline.HideCmd(cmd)
+	cmd.Dir = tmpdir
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	err = cmd.Run()
+	if err != nil {
+		return "", fmt.Errorf("Error running getgbook %s: %v", id, err)
+	}
+
+	select {
+	case <-ctx.Done():
+		_ = os.Remove(tmpdir)
+		return "", ctx.Err()
+	default:
+	}
+
+	// getgbook downloads into id directory, so move files out of
+	// there directly into dir
+	tmpdir = path.Join(tmpdir, id)
+	f, err := os.Open(tmpdir)
+	if err != nil {
+		return "", fmt.Errorf("Failed to open %s to move files: %v", tmpdir, err)
+	}
+	files, err := f.Readdir(0)
+	if err != nil {
+		return "", fmt.Errorf("Failed to readdir %s to move files: %v", tmpdir, err)
+	}
+
+	d := fmt.Sprintf("%s_%s_%s_%s", year, author, title, id)
+	dir := path.Join(basedir, d)
+	err = os.MkdirAll(dir, 0755)
+	if err != nil {
+		return "", fmt.Errorf("Couldn't create directory %s: %v", dir, err)
+	}
+
+	for _, v := range files {
+		orig := path.Join(tmpdir, v.Name())
+		new := path.Join(dir, v.Name())
+		err = moveFile(orig, new)
+		if err != nil {
+			return dir, fmt.Errorf("Failed to move %s to %s: %v", orig, new, err)
+		}
+	}
+
+	err = os.Remove(tmpdir)
+	if err != nil {
+		return dir, fmt.Errorf("Failed to remove temporary directory %s: %v", tmpdir, err)
+	}
+
+	return dir, nil
+}
+
+// getBookIdFromUrl returns a 12 character Google Book ID from
+// a Google URL, or an error if one can't be found.
+// Example URLs:
+// https://books.google.it/books?id=QjQepCuN8JYC
+// https://www.google.it/books/edition/_/VJbr-Oe2au0C
+func getBookIdFromUrl(url string) (string, error) {
+	lurl := strings.ToLower(url)
+	if len(url) == 12 && !strings.ContainsAny(url, "?/:") {
+		return url, nil
+	}
+
+	matchUrl, err := regexp.MatchString("https://www.google.[^\\/]*/books/", url)
+	if err != nil {
+		return "", err
+	}
+
+	if strings.HasPrefix(lurl, "https://books.google") {
+		start := strings.Index(lurl, "?id=")
+		if start == -1 {
+			start = strings.Index(lurl, "&id=")
+		}
+
+		if start >= 0 {
+			start += 4
+			if len(url) - start < 12 {
+				return "", fmt.Errorf("Could not find book ID in URL")
+			}
+			return url[start : start+12], nil
+		}
+
+		return "", fmt.Errorf("Could not find book ID in URL")
+	}
+	if matchUrl == true {
+		start := strings.Index(lurl, "edition/_/")
+
+		if start >= 0 {
+			start += 10
+			if len(url) - start < 12 {
+				return "", fmt.Errorf("Could not find book ID in URL")
+			}
+			return url[start : start+12], nil
+		}
+	}
+	return "", fmt.Errorf("Could not find book ID in URL")
+}