From 442f7b7c0cceeca6256396ea67dc594a90c7eb42 Mon Sep 17 00:00:00 2001
From: Alejandro Mery <amery@jpi.io>
Date: Mon, 28 Aug 2023 20:55:06 +0000
Subject: [PATCH] introduce NewReadCloser to allow byte and string buffers to
 offer io.ReadCloser

Signed-off-by: Alejandro Mery <amery@jpi.io>
---
 readcloser.go | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 readcloser.go

diff --git a/readcloser.go b/readcloser.go
new file mode 100644
index 0000000..4bc8b05
--- /dev/null
+++ b/readcloser.go
@@ -0,0 +1,69 @@
+package core
+
+import (
+	"bytes"
+	"io"
+	"io/fs"
+	"strings"
+)
+
+var (
+	_ io.Reader = (*ReadCloser)(nil)
+	_ io.Closer = (*ReadCloser)(nil)
+)
+
+// ReadCloser adds a Close() to Readers without one
+type ReadCloser struct {
+	r io.Reader
+}
+
+// Read passes the Read() call to the underlying [io.Reader]
+// and fail if it was Closed()
+func (rc *ReadCloser) Read(b []byte) (int, error) {
+	switch {
+	case rc.r != nil:
+		return rc.r.Read(b)
+	default:
+		return 0, fs.ErrClosed
+	}
+}
+
+// Close attempts to Close the underlying [io.Reader], or
+// remove it if it doesn't support Close() and fail
+// if closed twice
+func (rc *ReadCloser) Close() error {
+	switch {
+	case rc.r != nil:
+		rc.r = nil
+		return nil
+	default:
+		return fs.ErrClosed
+	}
+}
+
+// NewReadCloser wraps a [io.Reader] to satisfy
+// [io.ReadCloser] if needed
+func NewReadCloser(r io.Reader) io.ReadCloser {
+	switch p := r.(type) {
+	case io.ReadCloser:
+		return p
+	case nil:
+		return nil
+	default:
+		return &ReadCloser{
+			r: r,
+		}
+	}
+}
+
+// NewReadCloserBytes wraps a bytes slice to implement
+// a [io.ReadCloser]
+func NewReadCloserBytes(b []byte) io.ReadCloser {
+	return NewReadCloser(bytes.NewReader(b))
+}
+
+// NewReadCloserString wraps a string to implement
+// a [io.ReadCloser]
+func NewReadCloserString(s string) io.ReadCloser {
+	return NewReadCloser(strings.NewReader(s))
+}