docs: document methods and initialization in the git package

- Add comments to describe the purpose and functionality of various methods in the `Command` struct
- Document the `excludeFiles`, `diffNames`, `diffFiles`, `hookPath`, `gitDir`, `commit`, `Commit`, `DiffFiles`, `InstallHook`, `UninstallHook`, and `New` methods
- Add package-level documentation for the `git` package in `hook.go`
- Add comments for `HookPrepareCommitMessageTemplate` and `CommitMessageTemplate` constants
- Document the initialization process for Git hook templates in the `init` function

Signed-off-by: Bo-Yi Wu <[email protected]>

Author: appleboy

git/git.go

@@ -28,6 +28,8 @@ type Command struct {
 	isAmend     bool
 }
 
+// excludeFiles returns a list of files to be excluded from git operations.
+// It prepends each file in the excludeList with the exclude and top options.
 func (c *Command) excludeFiles() []string {
 	var excludedFiles []string
 	for _, f := range c.excludeList {
@@ -36,6 +38,8 @@ func (c *Command) excludeFiles() []string {
 	return excludedFiles
 }
 
+// diffNames generates the git command to list the names of changed files.
+// It includes options to handle amended commits and staged changes.
 func (c *Command) diffNames() *exec.Cmd {
 	args := []string{
 		"diff",
@@ -57,6 +61,9 @@ func (c *Command) diffNames() *exec.Cmd {
 	)
 }
 
+// diffFiles generates the git command to show the differences between files.
+// It includes options to ignore whitespace changes, use minimal diff algorithm,
+// and set the number of context lines.
 func (c *Command) diffFiles() *exec.Cmd {
 	args := []string{
 		"diff",
@@ -80,6 +87,8 @@ func (c *Command) diffFiles() *exec.Cmd {
 	)
 }
 
+// hookPath generates the git command to get the path of the hooks directory.
+// This is used to locate where git hooks are stored.
 func (c *Command) hookPath() *exec.Cmd {
 	args := []string{
 		"rev-parse",
@@ -93,6 +102,8 @@ func (c *Command) hookPath() *exec.Cmd {
 	)
 }
 
+// gitDir generates the git command to get the path of the git directory.
+// This is used to determine the location of the .git directory.
 func (c *Command) gitDir() *exec.Cmd {
 	args := []string{
 		"rev-parse",
@@ -105,6 +116,8 @@ func (c *Command) gitDir() *exec.Cmd {
 	)
 }
 
+// commit generates the git command to create a commit with the provided message.
+// It includes options to skip pre-commit hooks, sign off the commit, and handle amendments.
 func (c *Command) commit(val string) *exec.Cmd {
 	args := []string{
 		"commit",
@@ -123,6 +136,8 @@ func (c *Command) commit(val string) *exec.Cmd {
 	)
 }
 
+// Commit creates a git commit with the provided message and returns the output or an error.
+// It uses the commit method to generate the git command and execute it.
 func (c *Command) Commit(val string) (string, error) {
 	output, err := c.commit(val).Output()
 	if err != nil {
@@ -145,6 +160,9 @@ func (c *Command) GitDir() (string, error) {
 // Diff compares the differences between two sets of data.
 // It returns a string representing the differences and an error.
 // If there are no differences, it returns an empty string and an error.
+// DiffFiles compares the differences between two sets of data and returns the differences as a string and an error.
+// It first lists the names of changed files and then shows the differences between them.
+// If there are no staged changes, it returns an error message.
 func (c *Command) DiffFiles() (string, error) {
 	output, err := c.diffNames().Output()
 	if err != nil {
@@ -162,6 +180,8 @@ func (c *Command) DiffFiles() (string, error) {
 	return string(output), nil
 }
 
+// InstallHook installs the prepare-commit-msg hook if it doesn't already exist.
+// It retrieves the hooks directory path, checks if the hook file exists, and writes the hook file with executable permissions.
 func (c *Command) InstallHook() error {
 	hookPath, err := c.hookPath().Output()
 	if err != nil {
@@ -182,6 +202,8 @@ func (c *Command) InstallHook() error {
 	return os.WriteFile(target, content, 0o755) //nolint:gosec
 }
 
+// UninstallHook removes the prepare-commit-msg hook if it exists.
+// It retrieves the hooks directory path, checks if the hook file exists, and removes the hook file.
 func (c *Command) UninstallHook() error {
 	hookPath, err := c.hookPath().Output()
 	if err != nil {
@@ -195,6 +217,8 @@ func (c *Command) UninstallHook() error {
 	return os.Remove(target)
 }
 
+// New creates a new Command object with the provided options.
+// It applies each option to the config object and initializes the Command object with the configurations.
 func New(opts ...Option) *Command {
 	// Instantiate a new config object with default values
 	cfg := &config{}

git/hook.go

@@ -1,3 +1,10 @@
+// Package git provides functionality for working with git repositories.
+//
+// This package includes constants defining template names for git hooks and
+// initializes the templates from embedded files on package initialization.
+//
+// The package embeds files from a 'templates/' directory which contain hook templates
+// that can be used for git operations such as preparing commit messages.
 package git
 
 import (
@@ -11,10 +18,14 @@ import (
 var files embed.FS
 
 const (
+	// HookPrepareCommitMessageTemplate is the template for the prepare-commit-msg hook
 	HookPrepareCommitMessageTemplate = "prepare-commit-msg"
-	CommitMessageTemplate            = "commit-msg.tmpl"
+	// CommitMessageTemplate is the template for the commit message
+	CommitMessageTemplate = "commit-msg.tmpl"
 )
 
+// init initializes the Git hook templates by loading them from embedded files.
+// If there's an error loading the templates, the function logs a fatal error and terminates the program.
 func init() { //nolint:gochecknoinits
 	if err := util.LoadTemplates(files); err != nil {
 		log.Fatal(err)