From 6a715e809e15def425d9f2b8235d67ce82f3a39c Mon Sep 17 00:00:00 2001
From: Martin Helmich <m.helmich@mittwald.de>
Date: Fri, 24 Jan 2025 12:54:23 +0100
Subject: [PATCH] feat: add library code for mapping HTTP response errors onto
 specific error types

---
 pkg/httperr/from_response.go           | 16 ++++++++++++++++
 pkg/httperr/not_found_error.go         | 16 ++++++++++++++++
 pkg/httperr/permission_denied_error.go | 16 ++++++++++++++++
 3 files changed, 48 insertions(+)
 create mode 100644 pkg/httperr/from_response.go
 create mode 100644 pkg/httperr/not_found_error.go
 create mode 100644 pkg/httperr/permission_denied_error.go

diff --git a/pkg/httperr/from_response.go b/pkg/httperr/from_response.go
new file mode 100644
index 0000000..4948f9e
--- /dev/null
+++ b/pkg/httperr/from_response.go
@@ -0,0 +1,16 @@
+package httperr
+
+import "net/http"
+
+// ErrFromResponse maps an HTTP response (with an error status code) to a (more
+// or less) specific error type.
+func ErrFromResponse(res *http.Response) error {
+	switch res.StatusCode {
+	case http.StatusNotFound:
+		return &ErrNotFound{Response: res}
+	case http.StatusForbidden:
+		return &ErrPermissionDenied{Response: res}
+	default:
+		return &ErrUnexpectedResponse{Response: res}
+	}
+}
diff --git a/pkg/httperr/not_found_error.go b/pkg/httperr/not_found_error.go
new file mode 100644
index 0000000..2ceaabc
--- /dev/null
+++ b/pkg/httperr/not_found_error.go
@@ -0,0 +1,16 @@
+package httperr
+
+import (
+	"fmt"
+	"net/http"
+)
+
+// ErrNotFound represents the error of trying to access a resource that does
+// not exist.
+type ErrNotFound struct {
+	Response *http.Response
+}
+
+func (e *ErrNotFound) Error() string {
+	return fmt.Sprintf("resource not found: %s", e.Response.Request.URL)
+}
diff --git a/pkg/httperr/permission_denied_error.go b/pkg/httperr/permission_denied_error.go
new file mode 100644
index 0000000..fa0a211
--- /dev/null
+++ b/pkg/httperr/permission_denied_error.go
@@ -0,0 +1,16 @@
+package httperr
+
+import (
+	"fmt"
+	"net/http"
+)
+
+// ErrPermissionDenied represents the error of trying to access a resource that
+// the currently authenticated user is not authorized to access.
+type ErrPermissionDenied struct {
+	Response *http.Response
+}
+
+func (e *ErrPermissionDenied) Error() string {
+	return fmt.Sprintf("permission to resource denied: %s", e.Response.Request.URL)
+}