refactor(src/validator.go): Separating some validation logic.

src/validator.go

@@ -3,6 +3,19 @@
 
 package src
 
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"regexp"
+	"strings"
+
+	yaml "gopkg.in/yaml.v2"
+)
+
 var (
 	allowedHooks = []string{
 		"applypatch-msg",
@@ -20,6 +33,14 @@ var (
 	}
 )
 
+var (
+	fileModeMask         = fs.FileMode(0x1ff)
+	gitCommitMsgFile     = ".git/COMMIT_EDITMSG"
+	commitTypeConfigFile = ".polar-commitmsg-types.yaml"
+
+	commitMsgNotMatchErr = errors.New("Commit message not match.")
+)
+
 func Validate(name string) bool {
 	match := false
 
@@ -32,3 +53,89 @@ func Validate(name string) bool {
 
 	return match
 }
+
+func FetchSerializedCommitTypes() (string, error) {
+	finfo, err := os.Stat(commitTypeConfigFile)
+
+	if err != nil {
+		return "", err
+	}
+
+	f, err := os.OpenFile(commitTypeConfigFile, os.O_RDONLY, finfo.Mode()&fileModeMask)
+
+	if err != nil {
+		return "", err
+	}
+
+	buf := bytes.NewBuffer(nil)
+
+	io.Copy(buf, f)
+
+	if err := f.Close(); err != nil {
+		return "", err
+	}
+
+	types := make(map[string][]string, 0)
+
+	err = yaml.Unmarshal(buf.Bytes(), &types)
+
+	if err != nil {
+		return "", err
+	}
+
+	return strings.Join(types["types"], "|"), nil
+}
+
+func buildMatchingPattern(types string) (string, error) {
+	return fmt.Sprintf("^(?:%s)(?:\\(.*\\))(?:\\!)?(?:\\: )(.*)", types), nil
+}
+
+func FetchCommitMessage() ([]byte, error) {
+	buf := bytes.NewBuffer(nil)
+
+	finfo, err := os.Stat(gitCommitMsgFile)
+
+	if err != nil {
+		return nil, err
+	}
+
+	f, err := os.OpenFile(gitCommitMsgFile, os.O_RDONLY, finfo.Mode()&fileModeMask)
+
+	if err != nil {
+		return nil, err
+	}
+
+	io.Copy(buf, f)
+
+	if err := f.Close(); err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+func ValidateCommit(buf []byte) error {
+	types, err := FetchSerializedCommitTypes()
+
+	if err != nil {
+		return err
+	}
+
+	pat, err := buildMatchingPattern(types)
+
+	if err != nil {
+		return err
+	}
+
+	matched, err := regexp.Match(pat, buf)
+
+	if err != nil {
+		return err
+	}
+
+	if !matched {
+		return commitMsgNotMatchErr
+	}
+
+	return nil
+}