From 4a3acbea82326ce162e7e9dfa0f3b1c8a378dd4f Mon Sep 17 00:00:00 2001
From: Terry Cain <terry@terrys-home.co.uk>
Date: Wed, 11 May 2022 19:45:22 +0100
Subject: [PATCH] Added file lazy loading

---
 pkg/document/files.go      | 56 +++++++++++++++++++++++++-------------
 pkg/document/files_test.go | 15 +++++++---
 2 files changed, 48 insertions(+), 23 deletions(-)

diff --git a/pkg/document/files.go b/pkg/document/files.go
index 7f20fda..fdec92e 100644
--- a/pkg/document/files.go
+++ b/pkg/document/files.go
@@ -9,12 +9,31 @@ import (
 	"strings"
 
 	"github.com/gobwas/glob"
+	log "github.com/sirupsen/logrus"
 	"gopkg.in/yaml.v3"
 )
 
 // Near identical to https://github.com/helm/helm/blob/main/pkg/engine/files.go as to preserve the interface.
 
-type files map[string][]byte
+type fileEntry struct {
+	Path string
+	data []byte
+}
+
+func (f *fileEntry) GetData() []byte {
+	if f.data == nil {
+		data, err := ioutil.ReadFile(f.Path)
+		if err != nil {
+			log.Warnf("Error reading file contents for %s: %s", f.Path, err.Error())
+			return []byte{}
+		}
+		f.data = data
+	}
+
+	return f.data
+}
+
+type files map[string]*fileEntry
 
 func getFiles(dir string) (files, error) {
 	result := make(files)
@@ -28,17 +47,11 @@ func getFiles(dir string) (files, error) {
 			return nil
 		}
 
-		data, err := ioutil.ReadFile(path)
-		if err != nil {
-			return err
-		}
-
-		result[path] = data
-
+		result[path] = &fileEntry{Path: path}
 		return nil
 	})
 	if err != nil {
-		return map[string][]byte{}, err
+		return map[string]*fileEntry{}, err
 	}
 
 	return result, nil
@@ -46,7 +59,7 @@ func getFiles(dir string) (files, error) {
 
 func (f files) GetBytes(name string) []byte {
 	if v, ok := f[name]; ok {
-		return v
+		return v.GetData()
 	}
 	return []byte{}
 }
@@ -56,15 +69,16 @@ func (f files) Get(name string) string {
 }
 
 func (f files) Glob(pattern string) files {
+	result := make(files)
 	g, err := glob.Compile(pattern, '/')
 	if err != nil {
-		g, _ = glob.Compile("**")
+		log.Warnf("Error compiling Glob patten %s: %s", pattern, err.Error())
+		return result
 	}
 
-	result := make(files)
-	for name, contents := range f {
-		if g.Match(name) {
-			result[name] = contents
+	for filePath, entry := range f {
+		if g.Match(filePath) {
+			result[filePath] = entry
 		}
 	}
 
@@ -80,7 +94,7 @@ func (f files) AsConfig() string {
 
 	// Explicitly convert to strings, and file names
 	for k, v := range f {
-		m[path.Base(k)] = string(v)
+		m[path.Base(k)] = string(v.GetData())
 	}
 
 	return toYAML(m)
@@ -94,18 +108,22 @@ func (f files) AsSecrets() string {
 	m := make(map[string]string)
 
 	for k, v := range f {
-		m[path.Base(k)] = base64.StdEncoding.EncodeToString(v)
+		m[path.Base(k)] = base64.StdEncoding.EncodeToString(v.GetData())
 	}
 
 	return toYAML(m)
 }
 
 func (f files) Lines(path string) []string {
-	if f == nil || f[path] == nil {
+	if f == nil {
+		return []string{}
+	}
+	entry, exists := f[path]
+	if !exists {
 		return []string{}
 	}
 
-	return strings.Split(string(f[path]), "\n")
+	return strings.Split(string(entry.GetData()), "\n")
 }
 
 func toYAML(v interface{}) string {
diff --git a/pkg/document/files_test.go b/pkg/document/files_test.go
index 927cca9..769f33f 100644
--- a/pkg/document/files_test.go
+++ b/pkg/document/files_test.go
@@ -23,13 +23,17 @@ var cases = []struct {
 func getTestFiles() files {
 	a := make(files, len(cases))
 	for _, c := range cases {
-		a[c.path] = []byte(c.data)
+		a[c.path] = &fileEntry{
+			Path: c.path,
+			data: []byte(c.data),
+		}
 	}
 	return a
 }
 
 func TestNewFiles(t *testing.T) {
 	files := getTestFiles()
+
 	if len(files) != len(cases) {
 		t.Errorf("Expected len() = %d, got %d", len(cases), len(files))
 	}
@@ -97,14 +101,15 @@ func TestGetFiles(t *testing.T) {
 	})
 
 	testFiles := getTestFiles()
-	for filePath, fileData := range testFiles {
+	for filePath, entry := range testFiles {
 		fullPath := path.Join(chartDir, filePath)
 		baseDir := path.Dir(fullPath)
 		if err = os.MkdirAll(baseDir, 0o755); err != nil {
 			t.Fatal(err)
 		}
+		data := entry.GetData()
 
-		if err = os.WriteFile(fullPath, fileData, 0o644); err != nil {
+		if err = os.WriteFile(fullPath, data, 0o644); err != nil {
 			t.Fatal(err)
 		}
 	}
@@ -119,7 +124,9 @@ func TestGetFiles(t *testing.T) {
 	}
 
 	// Sanity check the files have been read
-	for filePath, data := range chartFiles {
+	for filePath, entry := range chartFiles {
+		data := entry.GetData()
+
 		if len(data) == 0 {
 			t.Errorf("%s: expected file contents, got 0 bytes", filePath)
 		}