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package main
import (
"flag"
"fmt"
"io"
"io/ioutil"
"log"
"net/http"
"os"
"path"
"strings"
)
const usage = `Usage: iiifdownloader url
Downloads all pages from a IIIF server.
`
const bnfPrefix = `https://gallica.bnf.fr/ark:/`
func filesAreIdentical(fn1, fn2 string) (bool, error) {
f1, err := os.Open(fn1)
defer f1.Close()
if err != nil {
return false, fmt.Errorf("Error opening file %s: %v\n", fn1, err)
}
b1, err := ioutil.ReadAll(f1)
if err != nil {
return false, fmt.Errorf("Error reading file %s: %v\n", fn1, err)
}
f2, err := os.Open(fn2)
defer f2.Close()
if err != nil {
return false, fmt.Errorf("Error opening file %s: %v\n", fn2, err)
}
b2, err := ioutil.ReadAll(f2)
if err != nil {
return false, fmt.Errorf("Error reading file %s: %v\n", fn2, err)
}
for i, _ := range b1 {
if b1[i] != b2[i] {
return false, nil
}
}
return true, nil
}
func main() {
flag.Usage = func() {
fmt.Fprintf(flag.CommandLine.Output(), usage)
flag.PrintDefaults()
}
flag.Parse()
if flag.NArg() < 1 {
flag.Usage()
return
}
url := flag.Arg(0)
var bookdir string
var pgurlStart, pgurlEnd string
var pgurlAltStart, pgurlAltEnd string
//var pgNums []int
var noPgNums bool
switch {
case strings.HasPrefix(url, bnfPrefix):
f := strings.Split(url[len(bnfPrefix):], "/")
if len(f) < 2 {
log.Fatalln("Failed to extract BNF book ID from URL")
}
bookid := f[0] + "/" + f[1]
bookdir = f[0] + "-" + f[1]
pgurlStart = "https://gallica.bnf.fr/iiif/ark:/" + bookid + "/f"
pgurlEnd = "/full/full/0/native.jpg"
noPgNums = true
// BNF don't have all pages available from IIIF, but they do have
// the missing ones in less good quality from an alternative URL.
pgurlAltStart = "https://gallica.bnf.fr/ark:/" + bookid + "/f"
pgurlAltEnd = ".highres"
default:
log.Fatalln("Error: generic IIIF downloading not supported yet")
}
err := os.MkdirAll(bookdir, 0777)
if err != nil {
log.Fatalf("Error creating book dir: %v\n", err)
}
if noPgNums {
pgnum := 0
for {
pgnum++
fmt.Printf("Downloading page %d\n", pgnum)
fn := path.Join(bookdir, fmt.Sprintf("%04d.jpg", pgnum))
_, err = os.Stat(fn)
if err == nil || os.IsExist(err) {
fmt.Printf("Skipping already present page %d\n", pgnum)
continue
}
u := fmt.Sprintf("%s%d%s", pgurlStart, pgnum, pgurlEnd)
resp, err := http.Get(u)
if err != nil {
log.Fatalf("Error downloading page %d, %s: %v\n", pgnum, u, err)
}
defer resp.Body.Close()
switch {
case resp.StatusCode == http.StatusNotFound:
fmt.Printf("Got 404, assuming end of pages, for page %d, %s\n", pgnum, u)
return
case resp.StatusCode != http.StatusOK:
fmt.Printf("Error downloading page %d, %s: HTTP Code %s\n", pgnum, u, resp.Status)
if pgurlAltStart == "" && pgurlAltEnd == "" {
log.Fatalln("No alternative URL to try, book failed (or ended, hopefully)")
}
fmt.Printf("Trying to redownload page %d at lower quality\n", pgnum)
u = fmt.Sprintf("%s%d%s", pgurlAltStart, pgnum, pgurlAltEnd)
resp, err = http.Get(u)
if err != nil {
log.Fatalf("Error downloading page %d, %s: %v\n", pgnum, u, err)
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
log.Fatalf("Error downloading page %d, %s: HTTP Code %s\n", pgnum, u, resp.Status)
}
}
f, err := os.Create(fn)
defer f.Close()
if err != nil {
log.Fatalf("Error creating file %s: %v\n", fn, err)
}
_, err = io.Copy(f, resp.Body)
if err != nil {
log.Fatalf("Error writing file %s: %v\n", fn, err)
}
// Close once finished with, as defer won't trigger until the end of the function
resp.Body.Close()
f.Close()
// Check that the last two downloaded files aren't identical, as this
// can happen when there are no more pages to download.
if pgnum == 1 {
continue
}
fn2 := path.Join(bookdir, fmt.Sprintf("%04d.jpg", pgnum-1))
identical, err := filesAreIdentical(fn, fn2)
if err != nil {
log.Fatalf("Error checking for files being identical: %v\n", err)
}
if identical {
fmt.Println("Last 2 pages were identical, looks like it's the end of the book")
err = os.Remove(fn)
if err != nil {
log.Fatalf("Error removing dupilicate page %d: %v", fn, err)
}
err = os.Remove(fn2)
if err != nil {
log.Fatalf("Error removing dupilicate page %d: %v", fn2, err)
}
return
}
}
}
}
|
