From: Colin P. Mccabe <colin@cmccabe.xyz>
Date: Wed, 19 Dec 2018 23:01:01 +0000 (-0800)
Subject: Add audiobooker
X-Git-Url: http://club.cc.cmu.edu/~cmccabe/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d603c8abd11dcfaa961ad0d52f11bf0ad502170a;p=cmccabe-bin

Add audiobooker
---

diff --git a/.gitignore b/.gitignore
index 9d11a70..74827ca 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,6 +15,7 @@ hexconv
 msgpack-translate
 directory_merge
 pickrand
+audiobooker
 
 #
 # Normal rules
diff --git a/audiobooker.go b/audiobooker.go
new file mode 100644
index 0000000..c330c89
--- /dev/null
+++ b/audiobooker.go
@@ -0,0 +1,229 @@
+package main
+
+import (
+	"os/exec"
+	"bufio"
+	"io"
+	"path/filepath"
+	"io/ioutil"
+	"fmt"
+	"os"
+	"sort"
+	"path"
+	"strings"
+)
+
+const MP3_SUFFIX = ".mp3"
+
+const TEMP_FILE_PREFIX = "audiobooker_"
+
+func checkInPath(inPath string) error {
+	if !strings.HasSuffix(inPath, MP3_SUFFIX) {
+		return fmt.Errorf("%s: not an mp3 file.\n", inPath)
+	}
+	_, err := os.Stat(inPath); if err != nil {
+		return fmt.Errorf("%s: %s", inPath, err)
+	}
+	return nil
+}
+
+func checkInPaths(inPaths []string) error {
+	for i := range inPaths {
+		err := checkInPath(inPaths[i]); if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func promptInPaths(inPaths []string) error {
+	fmt.Printf("FILES TO PROCESS:\n")
+	for i := range inPaths {
+		fmt.Printf("%s\n", inPaths[i])
+	}
+	fmt.Printf("PROCESS FILES? [Y/N]\n")
+	scanner := bufio.NewScanner(os.Stdin)
+	if !scanner.Scan() {
+		return fmt.Errorf("EOF reached on stdin.")
+	}
+	if scanner.Err() != nil {
+		return fmt.Errorf("Error reading stdin: %s.", scanner.Err().Error())
+	}
+	text := scanner.Text()
+	if text == "Y" || text == "y" {
+		return nil
+	}
+	if text == "N" || text == "n" {
+		return fmt.Errorf("User declined.")
+	}
+	return fmt.Errorf("Unknown input: %s.", text)
+}
+
+type OutDir struct {
+	outPath string
+	nextIndex int
+}
+
+func checkDirectoryIsEmpty(dirPath string) error {
+	d, err := os.Open(dirPath); if err != nil {
+		return fmt.Errorf("Unable to open directory %s: %s", dirPath, err.Error())
+	}
+	defer d.Close()
+	names, err := d.Readdirnames(3); if err != nil && err != io.EOF {
+		return fmt.Errorf("Unable to readdir %s: %s", dirPath, err.Error())
+	}
+	for i := range names {
+		if names[i] != "." || names[i] != ".." {
+			return fmt.Errorf("Directory %s is not empty: contained %s", dirPath, names[i])
+		}
+	}
+	return nil
+}
+
+func createOutDir(outPath string) (*OutDir, error) {
+	err := checkDirectoryIsEmpty(outPath); if err != nil {
+		return nil, fmt.Errorf("Invalid output directory: %s", err.Error())
+	}
+	return &OutDir {
+		outPath: outPath,
+		nextIndex: 0,
+	}, nil
+}
+
+func copyFileContents(dst, src string) error {
+	in, err := os.Open(src)
+	if err != nil {
+		return fmt.Errorf("Unable to open %s: %s", src, err.Error())
+	}
+	defer in.Close()
+	out, err := os.Create(dst)
+	if err != nil {
+		return fmt.Errorf("Unable to create %s: %s", dst, err.Error())
+	}
+	defer out.Close()
+	if _, err = io.Copy(out, in); err != nil {
+		return fmt.Errorf("Error copying data from %s to %s: %s",
+			src, dst, err.Error())
+	}
+	err = out.Sync()
+	if err != nil {
+		return fmt.Errorf("Failed to write %s: %s", dst, err.Error())
+	}
+	return err
+}
+
+func (out *OutDir) CopyFile(src string) error {
+	dst := path.Join(out.outPath,
+		fmt.Sprintf("%010d%s", out.nextIndex, filepath.Ext(src)))
+	err := copyFileContents(dst, src)
+	out.nextIndex++
+	return err
+}
+
+type InContext struct {
+	inPath string // The original input file path.
+	tempDir string // The path to the temporary directory.
+	srcPath string // The path to the copy of the source file.
+}
+
+func createInContext(inPath string) (*InContext, error) {
+	tempDir, err := ioutil.TempDir(os.TempDir(), TEMP_FILE_PREFIX); if err != nil {
+		return nil, fmt.Errorf("Error creating temp dir: %s", err.Error())
+	}
+	in := &InContext {
+		inPath: inPath,
+		tempDir: tempDir,
+		srcPath: path.Join(tempDir, "src"),
+	}
+	err = copyFileContents(in.srcPath, inPath)
+	if err != nil {
+		in.Cleanup()
+		return nil, err
+	}
+	return in, nil
+}
+
+func (in *InContext) Split() error {
+	command := exec.Command("mp3splt", "-t", "5.0", "-n", "-f",
+		"-o", TEMP_FILE_PREFIX + "@n", in.srcPath)
+	err := command.Run()
+	if err != nil {
+		return fmt.Errorf("mp3splt failed on %s: %s", in.srcPath, err.Error())
+	}
+	return nil
+}
+
+func (in *InContext) GetPaths() ([]string, error) {
+	d, err := os.Open(in.tempDir); if err != nil {
+		return nil, fmt.Errorf("Unable to open directory %s: %s", in.tempDir, err.Error())
+	}
+	defer d.Close()
+	names, err := d.Readdirnames(0); if err != nil && err != io.EOF {
+		return nil, fmt.Errorf("Unable to readdir %s: %s", in.tempDir, err.Error())
+	}
+	inPathBase := filepath.Base(in.srcPath)
+	paths := make([]string, 0, len(names))
+	for i := range names {
+		if names[i] != "." && names[i] != ".." && names[i] != inPathBase {
+			paths = append(paths, path.Join(in.tempDir, names[i]))
+		}
+	}
+	sort.Strings(paths)
+	return paths, nil
+}
+
+func (in *InContext) Cleanup() error {
+	return os.RemoveAll(in.tempDir)
+}
+
+func printUsage() {
+	fmt.Printf("audiobooker: splits audiobook mp3 files into 5 minute segments.\n")
+	fmt.Printf("usage: audiobooker [mp3 paths...]\n")
+	fmt.Printf("\n")
+	fmt.Printf("Note: the split mp3s will be stored in the current working directory.\n")
+}
+
+func main() {
+	if len(os.Args) < 2 {
+		printUsage()
+		os.Exit(0)
+	}
+	inPaths := os.Args[1:]
+	err := checkInPaths(inPaths); if err != nil {
+		fmt.Printf("Error: %s\n", err.Error())
+		os.Exit(1)
+	}
+	err = promptInPaths(inPaths); if err != nil {
+		fmt.Printf("%s\n", err.Error())
+		os.Exit(1)
+	}
+	outDir, err := createOutDir("."); if err != nil {
+		fmt.Printf("%s\n", err.Error())
+		os.Exit(1)
+	}
+	var totalFiles int64
+	for i := range inPaths {
+		in, err := createInContext(inPaths[i]); if err != nil {
+			fmt.Printf("Error processing %s: %s", inPaths[i], err.Error())
+			os.Exit(1)
+		}
+		defer in.Cleanup()
+		err = in.Split(); if err != nil {
+			fmt.Printf("%s\n", err.Error())
+			os.Exit(1)
+		}
+		paths, err := in.GetPaths(); if err != nil {
+			fmt.Printf("Error processing %s: %s", inPaths[i], err.Error())
+			os.Exit(1)
+		}
+		for j := range paths {
+			err = outDir.CopyFile(paths[j]); if err != nil {
+				fmt.Printf("Error processing %s: %s", inPaths[i], err.Error())
+				os.Exit(1)
+			}
+		}
+		fmt.Printf("Split %s into %d file(s)\n", inPaths[i], len(paths))
+		totalFiles += int64(len(paths))
+	}
+	fmt.Printf("Processed %d total file(s)\n", totalFiles)
+}