feat: item-attachments CRUD (#22)

* change /content/ -> /homebox/

* add cache to code generators

* update env variables to set data storage

* update env variables

* set env variables in prod container

* implement attachment post route (WIP)

* get attachment endpoint

* attachment download

* implement string utilities lib

* implement generic drop zone

* use explicit truncate

* remove clean dir

* drop strings composable for lib

* update item types and add attachments

* add attachment API

* implement service context

* consolidate API code

* implement editing attachments

* implement upload limit configuration

* improve error handling

* add docs for max upload size

* fix test cases

backend/pkgs/pathlib/pathlib.go

@@ -0,0 +1,64 @@
+package pathlib
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+type dirReaderFunc func(name string) []string
+
+var dirReader dirReaderFunc = func(directory string) []string {
+	f, err := os.Open(directory)
+	if err != nil {
+		return nil
+	}
+	defer f.Close()
+
+	names, err := f.Readdirnames(-1)
+	if err != nil {
+		return nil
+	}
+	return names
+}
+
+func hasConflict(path string, neighbors []string) bool {
+	filename := strings.ToLower(filepath.Base(path))
+
+	for _, n := range neighbors {
+		if strings.ToLower(n) == filename {
+			return true
+		}
+	}
+	return false
+}
+
+// Safe will take a destination path and return a validated path that is safe to use.
+// without overwriting any existing files. If a conflict exists, it will append a number
+// to the end of the file name. If the parent directory does not exist this function will
+// return the original path.
+func Safe(path string) string {
+	parent := filepath.Dir(path)
+
+	neighbors := dirReader(parent)
+	if neighbors == nil {
+		return path
+	}
+
+	if hasConflict(path, neighbors) {
+		ext := filepath.Ext(path)
+
+		name := strings.TrimSuffix(filepath.Base(path), ext)
+
+		for i := 1; i < 1000; i++ {
+			newName := fmt.Sprintf("%s (%d)%s", name, i, ext)
+			newPath := filepath.Join(parent, newName)
+			if !hasConflict(newPath, neighbors) {
+				return newPath
+			}
+		}
+	}
+
+	return path
+}