read and write index file

1 files changed, 116 insertions, 0 deletions

diff --git a/index.go b/index.go
new file mode 100644
index 0000000..967fe35
--- /dev/null
+++ b/index.go
@@ -0,0 +1,116 @@
+/*******************************************************************************
+*
+* Copyright 2017 Stefan Majewsky <majewsky@gmx.net>
+*
+* This program is free software: you can redistribute it and/or modify it under
+* the terms of the GNU General Public License as published by the Free Software
+* Foundation, either version 3 of the License, or (at your option) any later
+* version.
+*
+* This program is distributed in the hope that it will be useful, but WITHOUT ANY
+* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+* A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License along with
+* this program. If not, see <http://www.gnu.org/licenses/>.
+*
+*******************************************************************************/
+
+package main
+
+import (
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	yaml "gopkg.in/yaml.v2"
+)
+
+//Repo describes the entry for a repository in the index file.
+type Repo struct {
+	//Remotes maps remote names (as noted in the .git/config of the repo) to
+	//remote URLs (as they appear in the .git/config of the repo, i.e. possibly
+	//abbreviated).
+	Remotes map[string]string `yaml:"remotes"`
+	//CheckoutPath shall be relative to the Index.RootPath.
+	CheckoutPath string `yaml:"path"`
+}
+
+//Index represents the contents of the index file.
+type Index struct {
+	RootPath string `yaml:"root"`
+	Repos    []Repo `yaml:"repos"`
+}
+
+func indexPath() string {
+	homeDir := os.Getenv("HOME")
+	if homeDir == "" {
+		FatalIfError(errors.New("$HOME is not set"))
+	}
+	return filepath.Join(homeDir, ".rtree/index.yaml")
+}
+
+//ReadIndex reads the index file.
+func ReadIndex() *Index {
+	//read contents of index file
+	path := indexPath()
+	buf, err := ioutil.ReadFile(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			//initialize empty index
+			rootPath := os.Getenv("GOPATH")
+			if rootPath == "" {
+				FatalIfError(fmt.Errorf("cannot initialize %s ($GOPATH not set)", path))
+			}
+			return &Index{RootPath: rootPath}
+		}
+		FatalIfError(err)
+	}
+
+	//deserialize YAML
+	var index Index
+	FatalIfError(yaml.Unmarshal(buf, &index))
+
+	//validate YAML
+	valid := true
+	if index.RootPath == "" {
+		ShowError(errors.New("missing \"root\""))
+		valid = false
+	}
+	for idx, repo := range index.Repos {
+		if repo.CheckoutPath == "" {
+			ShowError(fmt.Errorf("missing \"repos[%d].path\"", idx))
+			valid = false
+		}
+		if len(repo.Remotes) == 0 {
+			ShowError(fmt.Errorf("missing \"repos[%d].remotes\"", idx))
+			valid = false
+		}
+		for remoteName, remoteURL := range repo.Remotes {
+			switch {
+			case remoteName == "":
+				ShowError(fmt.Errorf("empty remote name found in \"repos[%d]\"", idx))
+				valid = false
+			case remoteURL == "":
+				ShowError(fmt.Errorf("missing remote URL for remote \"%s\" in \"repos[%d]\"", idx, remoteName))
+				valid = false
+			}
+		}
+	}
+
+	if !valid {
+		FatalIfError(errors.New("index file is corrupted; see errors above"))
+	}
+	return &index
+}
+
+//Write writes the index file to disk.
+func (i *Index) Write() {
+	buf, err := yaml.Marshal(i)
+	FatalIfError(err)
+	path := indexPath()
+	FatalIfError(os.MkdirAll(filepath.Dir(path), 0755))
+	FatalIfError(ioutil.WriteFile(path, buf, 0644))
+}