init: create bundle list with one bundle

Create more helper packages in 'internal' space, including:

* repo: Information about a repository including the Git dir and
  location of the web content.

* core: Important information about the root of our filesystem data
  stores.

* bundles: Information about working with a bundle or a list of bundles.

Apply these new packages to complete the implementation of the 'init'
subcommand. It now creates the 'bundle-list' file in the web directory
and the 'bundle-list.json' file in the Git directory.

Author: derrickstolee

cmd/git-bundle-server/init.go

@@ -3,10 +3,9 @@ package main
 import (
 	"errors"
 	"fmt"
+	"git-bundle-server/internal/bundles"
+	"git-bundle-server/internal/core"
 	"git-bundle-server/internal/git"
-	"log"
-	"os"
-	"time"
 )
 
 type Init struct{}
@@ -24,28 +23,27 @@ func (Init) run(args []string) error {
 	url := args[0]
 	route := args[1]
 
-	repo := reporoot() + route
-	web := webroot() + route
-
-	mkdirErr := os.MkdirAll(web, os.ModePerm)
-	if mkdirErr != nil {
-		log.Fatal("Failed to create web directory: ", mkdirErr)
-	}
+	repo := core.GetRepository(route)
 
 	fmt.Printf("Cloning repository from %s\n", url)
-	gitErr := git.GitCommand("clone", "--mirror", url, repo)
+	gitErr := git.GitCommand("clone", "--mirror", url, repo.RepoDir)
 
 	if gitErr != nil {
-		return gitErr
+		return fmt.Errorf("failed to clone repository: %w", gitErr)
 	}
 
-	timestamp := time.Now().UTC().Unix()
-	bundleFile := web + "/bundle-" + fmt.Sprint(timestamp) + ".bundle"
-	fmt.Printf("Constructing base bundle file at %s\n", bundleFile)
+	bundle := bundles.CreateInitialBundle(repo)
+	fmt.Printf("Constructing base bundle file at %s\n", bundle.Filename)
 
-	gitErr = git.GitCommand("-C", repo, "bundle", "create", bundleFile, "--all")
+	gitErr = git.GitCommand("-C", repo.RepoDir, "bundle", "create", bundle.Filename, "--all")
 	if gitErr != nil {
-		return gitErr
+		return fmt.Errorf("failed to create bundle: %w", gitErr)
+	}
+
+	list := bundles.SingletonList(bundle)
+	listErr := bundles.WriteBundleList(list, repo)
+	if listErr != nil {
+		return fmt.Errorf("failed to write bundle list: %w", listErr)
 	}
 
 	return nil

cmd/git-bundle-server/subcommand.go

@@ -1,9 +1,5 @@
 package main
 
-import (
-	"os"
-)
-
 type Subcommand interface {
 	subcommand() string
 	run(args []string) error
@@ -14,21 +10,3 @@ func all() []Subcommand {
 		Init{},
 	}
 }
-
-func bundleroot() string {
-	dirname, err := os.UserHomeDir()
-	if err != nil {
-		// TODO: respond better. For now, try creating in "/var"
-		dirname = "/var"
-	}
-
-	return dirname + "/git-bundle-server/"
-}
-
-func webroot() string {
-	return bundleroot() + "www/"
-}
-
-func reporoot() string {
-	return bundleroot() + "git/"
-}

internal/bundles/bundles.go

@@ -1,8 +1,106 @@
 package bundles
 
-import "fmt"
+import (
+	"bufio"
+	"encoding/json"
+	"fmt"
+	"git-bundle-server/internal/core"
+	"os"
+	"time"
+)
 
-func BundleList() {
-	fmt.Printf("called bundleList\n")
-	fmt.Printf("\n");
+type Bundle struct {
+	URI           string
+	Filename      string
+	CreationToken int64
+}
+
+type BundleList struct {
+	Version int
+	Mode    string
+	Bundles map[int64]Bundle
+}
+
+func addBundleToList(bundle Bundle, list BundleList) {
+	list.Bundles[bundle.CreationToken] = bundle
+}
+
+func CreateInitialBundle(repo core.Repository) Bundle {
+	timestamp := time.Now().UTC().Unix()
+	bundleName := "bundle-" + fmt.Sprint(timestamp) + ".bundle"
+	bundleFile := repo.WebDir + "/" + bundleName
+	bundle := Bundle{
+		URI:           "./" + bundleName,
+		Filename:      bundleFile,
+		CreationToken: timestamp,
+	}
+
+	return bundle
+}
+
+func SingletonList(bundle Bundle) BundleList {
+	list := BundleList{1, "all", make(map[int64]Bundle)}
+
+	addBundleToList(bundle, list)
+
+	return list
+}
+
+// Given a BundleList
+func WriteBundleList(list BundleList, repo core.Repository) error {
+	listFile := repo.WebDir + "/bundle-list"
+	jsonFile := repo.RepoDir + "/bundle-list.json"
+
+	// TODO: Formalize lockfile concept.
+	f, err := os.OpenFile(listFile+".lock", os.O_WRONLY|os.O_CREATE, 0600)
+	if err != nil {
+		return fmt.Errorf("failure to open file: %w", err)
+	}
+
+	out := bufio.NewWriter(f)
+
+	fmt.Fprintf(
+		out, "[bundle]\n\tversion = %d\n\tmode = %s\n\n",
+		list.Version, list.Mode)
+
+	for token, bundle := range list.Bundles {
+		fmt.Fprintf(
+			out, "[bundle \"%d\"]\n\turi = %s\n\tcreationToken = %d\n\n",
+			token, bundle.URI, token)
+	}
+
+	out.Flush()
+	err = f.Close()
+	if err != nil {
+		return fmt.Errorf("failed to close lock file: %w", err)
+	}
+
+	f, err = os.OpenFile(jsonFile+".lock", os.O_WRONLY|os.O_CREATE, 0600)
+	if err != nil {
+		return fmt.Errorf("failed to open JSON file: %w", err)
+	}
+
+	data, jsonErr := json.Marshal(list)
+	if jsonErr != nil {
+		return fmt.Errorf("failed to convert list to JSON: %w", err)
+	}
+
+	written := 0
+	for written < len(data) {
+		n, writeErr := f.Write(data[written:])
+		if writeErr != nil {
+			return fmt.Errorf("failed to write JSON: %w", err)
+		}
+		written += n
+	}
+
+	f.Sync()
+	f.Close()
+
+	renameErr := os.Rename(jsonFile+".lock", jsonFile)
+	if renameErr != nil {
+		return fmt.Errorf("failed to rename JSON file: %w", renameErr)
+	}
+
+	return os.Rename(listFile+".lock", listFile)
 }

internal/core/paths.go

@@ -0,0 +1,21 @@
+package core
+
+import "os"
+
+func bundleroot() string {
+	dirname, err := os.UserHomeDir()
+	if err != nil {
+		// TODO: respond better. For now, try creating in "/var"
+		dirname = "/var"
+	}
+
+	return dirname + "/git-bundle-server/"
+}
+
+func webroot() string {
+	return bundleroot() + "www/"
+}
+
+func reporoot() string {
+	return bundleroot() + "git/"
+}

internal/core/repo.go

@@ -0,0 +1,28 @@
+package core
+
+import (
+	"log"
+	"os"
+)
+
+type Repository struct {
+	Route   string
+	RepoDir string
+	WebDir  string
+}
+
+func GetRepository(route string) Repository {
+	repo := reporoot() + route
+	web := webroot() + route
+
+	mkdirErr := os.MkdirAll(web, os.ModePerm)
+	if mkdirErr != nil {
+		log.Fatal("failed to create web directory: ", mkdirErr)
+	}
+
+	return Repository{
+		Route:   route,
+		RepoDir: repo,
+		WebDir:  web,
+	}
+}