1 files changed, 86 insertions, 0 deletions

diff --git a/mapper.go b/mapper.go
new file mode 100644
index 0000000..ca6885b
--- /dev/null
+++ b/mapper.go
@@ -0,0 +1,86 @@
+package envcfg
+
+import (
+        "os"
+        "reflect"
+        "strconv"
+        "strings"
+)
+
+func getEnvName(n node) string {
+        name := n.properties.Tag.Get(TAG)
+        if name == "" {
+                name = n.properties.Name
+        }
+
+        abs, _ := strconv.ParseBool(n.properties.Tag.Get(ABS_TAG))
+        if !abs && n.parent != nil {
+                if n.parent.properties != nil {
+                        parentName := getEnvName(*n.parent)
+                        name = parentName + SEP + name
+                }
+        }
+
+        return strings.ToUpper(name)
+}
+
+func setValue(n node, v string) (node, error) {
+        switch n.value.Kind() {
+        case reflect.String:
+                n.value.SetString(v)
+
+        case reflect.Bool:
+                boolVal, err := strconv.ParseBool(v)
+                if err != nil {
+                        return n, err
+                }
+                n.value.SetBool(boolVal)
+
+        case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+                intVal, err := strconv.ParseInt(v, 0, n.value.Type().Bits())
+                if err != nil {
+                        return n, err
+                }
+                n.value.SetInt(intVal)
+
+        case reflect.Float32, reflect.Float64:
+                floatVal, err := strconv.ParseFloat(v, n.value.Type().Bits())
+                if err != nil {
+                        return n, err
+                }
+                n.value.SetFloat(floatVal)
+        }
+
+        return n, nil
+}
+
+func setFieldValue(n node) (node, error) {
+        if n.value.Kind() == reflect.Struct {
+                setStructFields(n)
+                return n, nil
+        }
+
+        v := os.Getenv(getEnvName(n))
+        if v != "" {
+                return setValue(n, v)
+        }
+
+        return n, nil
+}
+
+func setStructFields(n node) (node, []error) {
+        t := n.value.Type()
+        errs := []error{}
+
+        for i := 0; i < n.value.NumField(); i++ {
+                v := n.value.Field(i)
+                p := t.Field(i)
+
+                _, err := setFieldValue(node{&n, &v, &p})
+                if err != nil {
+                        errs = append(errs, err)
+                }
+        }
+
+        return n, errs
+}