wip refactoring: better logging and error systems

internal/pkg/standarderror/doc.go

@@ -0,0 +1,5 @@
+// Package standarderror helps standardizing
+// the errors in the application.
+//
+// Credits: https://middlemost.com/failure-is-your-domain/
+package standarderror

internal/pkg/standarderror/standarderror.go

@@ -0,0 +1,85 @@
+package standarderror
+
+import (
+	"bytes"
+	"fmt"
+)
+
+const (
+	// Internal is a code
+	// for internal errors.
+	Internal = "internal"
+	// Invalid is a code
+	// for validation errors.
+	Invalid = "invalid"
+	// Timeout is a code
+	// for timeout errors.
+	Timeout = "timeout"
+)
+
+// Error defines a standard application
+// error.
+type Error struct {
+	// Code is a machine-readable
+	// error code.
+	Code string
+	// Message is a human-readable
+	// message.
+	Message string
+	// Op is a logical operation.
+	Op string
+	// Err is a nested error.
+	Err error
+}
+
+// Error returns the string representation of the error message.
+func (err *Error) Error() string {
+	var buf bytes.Buffer
+	// print the current operation in our stack, if any.
+	if err.Op != "" {
+		fmt.Fprintf(&buf, "%s: ", err.Op)
+	}
+	// if wrapping an error, print its Error() message.
+	// Otherwise print the error code & message.
+	if err.Err != nil {
+		buf.WriteString(err.Err.Error())
+	} else {
+		if err.Code != "" {
+			fmt.Fprintf(&buf, "<%s> ", err.Code)
+		}
+		buf.WriteString(err.Message)
+	}
+	return buf.String()
+}
+
+// Code returns the code of the root error, if available.
+// Otherwise returns Internal.
+func Code(err error) string {
+	if err == nil {
+		return ""
+	}
+	e, ok := err.(*Error)
+	if ok && e.Code != "" {
+		return e.Code
+	}
+	if ok && e.Err != nil {
+		return Code(e.Err)
+	}
+	return Internal
+}
+
+// Message returns the human-readable message of the error, if available.
+// Otherwise returns a generic error message.
+func Message(err error) string {
+	if err == nil {
+		return ""
+	}
+	e, ok := err.(*Error)
+	if ok && e.Message != "" {
+		return e.Message
+	}
+	if ok && e.Err != nil {
+		return Message(e.Err)
+	}
+	return "An internal error has occurred. Please contact technical support."
+}