add calculate and merge coverage files

internal/analyzer/coverage/git.go

@@ -0,0 +1,70 @@
+package coverage
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing/filemode"
+	"github.com/go-git/go-git/v5/plumbing/object"
+	"github.com/go-git/go-git/v5/storage/memory"
+	"os"
+	"regexp"
+	"strings"
+)
+
+var (
+	fileNil = errors.New("file pointer is nil")
+)
+
+func GetTreeFromGit(ctx context.Context, url string) (*Tree, error) {
+	cloneOpts := &git.CloneOptions{
+		URL:      url,
+		Progress: os.Stdout,
+	}
+
+	repo, err := git.CloneContext(ctx, memory.NewStorage(), nil, cloneOpts)
+	if err != nil {
+		return nil, err
+	}
+
+	ref, err := repo.Head()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get head: %v", err)
+	}
+
+	commit, err := repo.CommitObject(ref.Hash())
+	if err != nil {
+		return nil, fmt.Errorf("failed to get commit: %v", err)
+	}
+
+	tree, err := commit.Tree()
+
+	return &Tree{tree}, err
+}
+
+type Tree struct {
+	*object.Tree
+}
+
+func (t Tree) GoFileList(pattern string) ([]string, error) {
+	matcher, err := regexp.Compile(pattern)
+	if err != nil {
+		return nil, err
+	}
+
+	var list []string
+	err = t.Files().ForEach(func(file *object.File) error {
+		if file == nil {
+			return fileNil
+		}
+		if file.Mode == filemode.Regular && strings.HasSuffix(file.Name, ".go") && !strings.HasSuffix(file.Name, "_test.go") && matcher.MatchString(file.Name) {
+			list = append(list, file.Name)
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	return list, err
+}