feat: add configurable file ignore patterns

internal/git/.gitcommitsummaryignore

@@ -0,0 +1,8 @@
+*-lock.*
+*.lock
+.yarn/releases/**
+**/build/**
+**/dist/**
+**/target/**
+**/out/**
+go.sum

internal/git/client.go

@@ -3,6 +3,7 @@ package git
 import (
 	"bytes"
 	"context"
+	_ "embed"
 	"fmt"
 	"io"
 	"os"
@@ -122,16 +123,10 @@ func (c *Client) diffArgs(color, exclude bool) []string {
 	if exclude {
 		args = append(args,
 			"--diff-filter=ACMRTUXBD",
-			"--",                 // separates options from pathspecs
-			".",                  // include everything under the repo root
-			":(exclude)*-lock.*", // package-lock.json, pnpm-lock.yaml, etc.
-			":(exclude)*.lock",   // yarn.lock, poetry.lock, Cargo.lock, etc.
-			":(exclude)**/build/**",
-			":(exclude)**/dist/**",
-			":(exclude)**/target/**",
-			":(exclude)**/out/**",
-			":(exclude)go.sum",
+			"--", // separates options from pathspecs
+			".",  // include everything under the repo root
 		)
+		args = append(args, exclusions()...)
 	}
 	return args
 }

internal/git/exclusions.go

@@ -0,0 +1,120 @@
+package git
+
+import (
+	_ "embed"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+
+	"github.com/adrg/xdg"
+)
+
+//go:embed .gitcommitsummaryignore
+var defaultGitCommitSummaryIgnore string
+
+func exclusions() []string {
+	var excludes []string
+	for _, content := range []string{
+		defaultGitCommitSummaryIgnore,
+		userHomeGitCommitSummaryIgnore(),
+		projectGitCommitSummaryIgnore(),
+		xdgConfigGitCommitSummaryIgnore(),
+	} {
+		for line := range strings.SplitSeq(content, "\n") {
+			// remove any comment (hash or double-slash) at the end of the line
+			if idx := strings.Index(line, "#"); idx != -1 {
+				line = line[:idx]
+			}
+
+			if idx := strings.Index(line, "//"); idx != -1 {
+				line = line[:idx]
+			}
+
+			line = strings.TrimSpace(line)
+			if line == "" {
+				continue
+			}
+
+			if !validateIgnorePattern(line) {
+				continue
+			}
+
+			excludes = append(excludes, ":(exclude)"+line)
+		}
+	}
+	return dedupe(excludes)
+}
+
+func dedupe(excludes []string) []string {
+	seen := make(map[string]struct{})
+	var result []string
+	for _, exclude := range excludes {
+		if _, ok := seen[exclude]; !ok {
+			seen[exclude] = struct{}{}
+			result = append(result, exclude)
+		}
+	}
+	return result
+}
+
+func projectGitCommitSummaryIgnore() string {
+	cwd, err := os.Getwd()
+	if err != nil {
+		return ""
+	}
+
+	for {
+		ignorePath := filepath.Join(cwd, ".gitcommitsummaryignore")
+		if data, err := os.ReadFile(ignorePath); err == nil {
+			return string(data)
+		}
+
+		parent := filepath.Dir(cwd)
+		if parent == cwd {
+			break
+		}
+		cwd = parent
+	}
+
+	return ""
+}
+
+func userHomeGitCommitSummaryIgnore() string {
+	homeDir, err := os.UserHomeDir()
+	if err != nil {
+		return ""
+	}
+	return readFileString(filepath.Join(homeDir, ".gitcommitsummaryignore"))
+}
+
+func xdgConfigGitCommitSummaryIgnore() string {
+	config, err := xdg.SearchConfigFile("git-commit-summary/.gitcommitsummaryignore")
+	if err != nil {
+		return ""
+	}
+	return readFileString(config)
+}
+
+func validateIgnorePattern(pattern string) bool {
+	if strings.ContainsRune(pattern, 0) {
+		return false
+	}
+	if strings.HasPrefix(pattern, "!") {
+		return false
+	}
+	if strings.Contains(pattern, "\\") {
+		return false
+	}
+
+	_, err := path.Match(pattern, pattern)
+	return err == nil
+}
+
+func readFileString(path string) string {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return ""
+	}
+	return string(data)
+}

internal/git/exclusions_test.go

@@ -0,0 +1,53 @@
+package git
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestProjectGitCommitSummaryIgnore(t *testing.T) {
+	tempDir := t.TempDir()
+	repoDir := filepath.Join(tempDir, "repo", "subdir")
+	assert.NoError(t, os.MkdirAll(repoDir, 0o755))
+
+	ignoreFile := filepath.Join(tempDir, "repo", ".gitcommitsummaryignore")
+	assert.NoError(t, os.WriteFile(ignoreFile, []byte("ignored-file.txt\n"), 0o644))
+
+	t.Chdir(repoDir)
+
+	actual := projectGitCommitSummaryIgnore()
+	assert.Equal(t, "ignored-file.txt\n", actual)
+}
+
+func TestUserHomeGitCommitSummaryIgnore(t *testing.T) {
+	tempHome := t.TempDir()
+	t.Setenv("HOME", tempHome)
+	t.Setenv("USERPROFILE", tempHome)
+
+	ignoreFile := filepath.Join(tempHome, ".gitcommitsummaryignore")
+	assert.NoError(t, os.WriteFile(ignoreFile, []byte("*.secret\n"), 0o644))
+
+	actual := userHomeGitCommitSummaryIgnore()
+	assert.Equal(t, "*.secret\n", actual)
+}
+
+func TestValidateIgnorePattern_InvalidGlob(t *testing.T) {
+	assert.False(t, validateIgnorePattern("[unclosed.glob"))
+}
+
+func TestDedupeExclusions(t *testing.T) {
+	excludes := []string{
+		":(exclude)foo.txt",
+		":(exclude)bar.txt",
+		":(exclude)foo.txt",
+	}
+
+	result := dedupe(excludes)
+	assert.Equal(t, []string{
+		":(exclude)foo.txt",
+		":(exclude)bar.txt",
+	}, result)
+}