From 9072d798c89c152c22f56eca6ae02d1bbbfd37e7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Benouarets?= <bbenouarets@proton.me>
Date: Thu, 22 Jan 2026 12:14:49 +0100
Subject: [PATCH] init: Initial commit

---
 README.md |  60 ++++++++++++++++++++++++++++++++
 go.mod    |   3 ++
 mapper.go | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 163 insertions(+)
 create mode 100644 README.md
 create mode 100644 go.mod
 create mode 100644 mapper.go

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..246ab3e
--- /dev/null
+++ b/README.md
@@ -0,0 +1,60 @@
+# Go JSON Mapper (gojsonmapper)
+
+This is a simple library that allows you to map different JSON objects to each other.
+
+## Example
+
+This example shows how to map a JSON object to another JSON object.
+
+### Mapping
+
+```json
+{
+    "name": "data.name",
+    "address": "data.addresses[0]"
+}
+````
+
+### Input JSON
+
+```json
+{
+    "data": {
+        "name": "John Doe",
+        "addresses": [
+            "123 Main St"
+        ]
+    }
+}
+```
+
+### Output JSON
+
+```json
+{
+    "name": "John Doe",
+    "address": "123 Main St"
+}
+```
+
+## Usage
+
+### Read Mapping
+
+```go
+mapping, err := ReadMapping("mapping.json")
+if err != nil {
+    log.Fatal(err)
+}
+```
+
+### Map Input
+
+```go
+mapper := NewMapper(mapping)
+output, err := mapper.Map(input)
+if err != nil {
+    log.Fatal(err)
+}
+fmt.Println(output)
+```
\ No newline at end of file
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..a78aedf
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module git.secnex.io/secnex/gojsonmapper
+
+go 1.25.5
diff --git a/mapper.go b/mapper.go
new file mode 100644
index 0000000..8975118
--- /dev/null
+++ b/mapper.go
@@ -0,0 +1,100 @@
+package gojsonmapper
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"strings"
+)
+
+type Mapper struct {
+	mapping map[string]string
+}
+
+func ReadMapping(path string) (map[string]string, error) {
+	jsonData, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	var mapping map[string]string
+	err = json.Unmarshal(jsonData, &mapping)
+	return mapping, nil
+}
+
+func NewMapper(mapping map[string]string) *Mapper {
+	return &Mapper{mapping: mapping}
+}
+
+func (m *Mapper) Map(input map[string]interface{}) (map[string]interface{}, error) {
+	output := make(map[string]interface{})
+	for key, path := range m.mapping {
+		output[key] = navigatePath(input, path)
+	}
+	return output, nil
+}
+
+func navigatePath(current map[string]interface{}, path string) interface{} {
+	parts := strings.Split(path, ".")
+	for i, part := range parts {
+		isLast := i == len(parts)-1
+		if strings.Contains(part, "[") && strings.HasSuffix(part, "]") {
+			key := part[:strings.Index(part, "[")]
+			indexStr := part[strings.Index(part, "[")+1 : len(part)-1]
+
+			if current[key] == nil {
+				return nil
+			}
+			arr, ok := current[key].([]interface{})
+			if !ok {
+				return nil
+			}
+
+			// Handle mapping all elements: key[]
+			if indexStr == "" {
+				if isLast {
+					return arr
+				}
+				remainingPath := strings.Join(parts[i+1:], ".")
+				result := make([]interface{}, len(arr))
+				for j, item := range arr {
+					if nestedMap, ok := item.(map[string]interface{}); ok {
+						result[j] = navigatePath(nestedMap, remainingPath)
+					}
+				}
+				return result
+			}
+
+			// Handle specific index: key[0]
+			var index int
+			fmt.Sscanf(indexStr, "%d", &index)
+			if index < 0 || index >= len(arr) {
+				return nil
+			}
+
+			if isLast {
+				return arr[index]
+			}
+
+			if nestedMap, ok := arr[index].(map[string]interface{}); ok {
+				remainingPath := strings.Join(parts[i+1:], ".")
+				return navigatePath(nestedMap, remainingPath)
+			}
+			return nil
+		}
+
+		// Regular key access
+		if isLast {
+			return current[part]
+		}
+
+		if current[part] == nil {
+			return nil
+		}
+		var ok bool
+		current, ok = current[part].(map[string]interface{})
+		if !ok {
+			return nil
+		}
+	}
+	return current
+}