From 5ee22a06ee88ad2cc3be23e381192ad0746e92fa Mon Sep 17 00:00:00 2001
From: Brandon Dyck <brandon@dyck.us>
Date: Wed, 23 Nov 2022 16:54:08 -0700
Subject: [PATCH] Added filesystem abstraction

---
 fs/fs.go        | 69 +++++++++++++++++++++++++++++++++++++++++++++++++
 fsstuff/main.go | 56 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 125 insertions(+)
 create mode 100644 fs/fs.go
 create mode 100644 fsstuff/main.go

diff --git a/fs/fs.go b/fs/fs.go
new file mode 100644
index 0000000..4005d1d
--- /dev/null
+++ b/fs/fs.go
@@ -0,0 +1,69 @@
+package fs
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+type FS interface {
+	isFS()
+}
+
+type DirEntry struct {
+	Name string
+	FS   FS
+}
+
+type Entries interface {
+	Get() []DirEntry
+}
+
+type Dir struct {
+	Entries
+}
+
+func (d Dir) isFS() {}
+
+type Contents interface {
+	Get() io.Reader
+}
+
+type File struct {
+	Contents
+}
+
+func (f File) isFS() {}
+
+func Realize(path string, f FS) error {
+	if f == nil {
+		return fmt.Errorf("cannot realize nil FS at %s", path)
+	}
+	switch t := f.(type) {
+	case File:
+		osf, err := os.Create(path)
+		if err != nil {
+			return fmt.Errorf("cannot create file %s: %w", path, err)
+		}
+		defer osf.Close()
+		_, err = io.Copy(osf, t.Get())
+		if err != nil {
+			return fmt.Errorf("cannot write file %s: %w", path, err)
+		}
+	case Dir:
+		err := os.Mkdir(path, 0666)
+		if err != nil {
+			return fmt.Errorf("cannot create dir %s: %w", path, err)
+		}
+		for _, child := range t.Get() {
+			err := Realize(filepath.Join(path, child.Name), child.FS)
+			if err != nil {
+				return err
+			}
+		}
+	default:
+		panic("unknown File type")
+	}
+	return nil
+}
diff --git a/fsstuff/main.go b/fsstuff/main.go
new file mode 100644
index 0000000..0cdae04
--- /dev/null
+++ b/fsstuff/main.go
@@ -0,0 +1,56 @@
+package main
+
+import (
+	"io"
+	"log"
+	"strings"
+
+	"git.codemonkeysoftware.net/b/sbsqlitessgcms/fs"
+)
+
+type File string
+
+func (f File) Get() io.Reader {
+	return strings.NewReader(string(f))
+}
+
+type Dir map[string]interface{}
+
+func (d Dir) Get() []fs.DirEntry {
+	var entries []fs.DirEntry
+	for name, child := range d {
+		entry := fs.DirEntry{
+			Name: name,
+		}
+		switch t := child.(type) {
+		case File:
+			entry.FS = fs.File{Contents: t}
+		case Dir:
+			entry.FS = fs.Dir{Entries: t}
+		default:
+			panic("aw hell naw")
+		}
+		entries = append(entries, entry)
+	}
+	return entries
+}
+
+func main() {
+	dir := fs.Dir{
+		Entries: Dir{
+			"a": File("apple"),
+			"b": File("bootilicious"),
+			"c": File("curveball"),
+			"d": Dir{
+				"e": File("ectoplasm"),
+				"f": File("^&*("),
+				"g": File("grrrl power"),
+				"h": File("hellabyte"),
+			},
+		},
+	}
+	err := fs.Realize("./stuff", dir)
+	if err != nil {
+		log.Fatal(err)
+	}
+}