From 55c201b36cfc555bc2ed109cfce0c5d306197293 Mon Sep 17 00:00:00 2001
From: Sean Hickey <tallirishllama@gmail.com>
Date: Sat, 18 Jun 2022 12:44:10 -0700
Subject: [PATCH] Add ability to override values with cli flags

---
 Makefile             |  6 +++---
 Readme.md            | 15 +++++++++++++-
 gosimpleconf.go      | 47 ++++++++++++++++++++++++++++++++++++++++----
 gosimpleconf_test.go | 43 ++++++++++++++++++++++++++++++++++++----
 4 files changed, 99 insertions(+), 12 deletions(-)

diff --git a/Makefile b/Makefile
index b9d53b9..f1a96dd 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
-all: test
+all: linter test
 
-test: linter
-	go test
+test:
+	go test ./
 
 linter:
 	golangci-lint run
diff --git a/Readme.md b/Readme.md
index 7c07d96..bd1bbe9 100644
--- a/Readme.md
+++ b/Readme.md
@@ -1,7 +1,7 @@
 # gosimpleconf
 
 ```sh
-go get gitea.wisellama.rocks/Wisellama/gosimpleconf@v0.0.2
+go get gitea.wisellama.rocks/Wisellama/gosimpleconf@v0.0.3
 ```
 
 This is a small library for parsing super simple configuration files.
@@ -39,6 +39,19 @@ var piStr string = configMap["pi"]
 pi, err := strconv.ParseFloat(value, 64)
 ```
 
+To override values with cli flags, after parsing the conf file you can
+use these functions to also parse the flags:
+```go
+flagMap := SetupFlagOverrides(configMap)
+configMap = ParseFlags(configMap, flagmap)
+```
+
+Then you could, for example, override the url value without modifying
+the config file:
+```go
+./program --url=newthing.wisellama.rocks
+```
+
 ## Why?
 
 I've always seen configuration files similar to this show up in
diff --git a/gosimpleconf.go b/gosimpleconf.go
index f181f3e..b1eacea 100644
--- a/gosimpleconf.go
+++ b/gosimpleconf.go
@@ -2,13 +2,19 @@ package gosimpleconf
 
 import (
 	"bufio"
+	"flag"
 	"fmt"
 	"io"
+	"log"
 	"os"
+	"strconv"
 	"strings"
 )
 
-func Load(filename string) (map[string]string, error) {
+type ConfigMap map[string]string
+type FlagMap map[string]*string
+
+func Load(filename string) (ConfigMap, error) {
 	var err error
 
 	file, err := os.Open(filename)
@@ -17,7 +23,7 @@ func Load(filename string) (map[string]string, error) {
 	}
 	defer file.Close()
 
-	parsedMap, err := parse(file)
+	parsedMap, err := parseFile(file)
 	if err != nil {
 		return nil, err
 	}
@@ -25,9 +31,42 @@ func Load(filename string) (map[string]string, error) {
 	return parsedMap, nil
 }
 
-func parse(config io.Reader) (map[string]string, error) {
+func SetupFlagOverrides(configMap ConfigMap) FlagMap {
+	flagMap := make(FlagMap)
+	for k, v := range configMap {
+		f := flag.String(k, v, "")
+		flagMap[k] = f
+	}
+
+	return flagMap
+}
+
+func ParseFlags(configMap ConfigMap, flagMap FlagMap) ConfigMap {
+	flag.Parse()
+
+	for k, v := range flagMap {
+		if v != nil && len(*v) > 0 {
+			configMap[k] = *v
+		}
+	}
+
+	return configMap
+
+}
+
+func Bool(value string) bool {
+	v, err := strconv.ParseBool(value)
+	if err != nil {
+		log.Printf("error parsing bool %v - %v", v, err)
+		v = false
+	}
+
+	return v
+}
+
+func parseFile(config io.Reader) (ConfigMap, error) {
 	var err error
-	parsedMap := make(map[string]string)
+	parsedMap := make(ConfigMap)
 
 	scanner := bufio.NewScanner(config)
 	for scanner.Scan() {
diff --git a/gosimpleconf_test.go b/gosimpleconf_test.go
index 95e981d..44d6e3c 100644
--- a/gosimpleconf_test.go
+++ b/gosimpleconf_test.go
@@ -1,6 +1,7 @@
 package gosimpleconf
 
 import (
+	"flag"
 	"strings"
 	"testing"
 )
@@ -25,7 +26,7 @@ technically valid = haha hmm...
 `
 	configFile := strings.NewReader(configFileStr)
 
-	expectedMap := make(map[string]string)
+	expectedMap := make(ConfigMap)
 	expectedMap["foo"] = "bar"
 	expectedMap["asdf"] = "1234"
 	expectedMap["wat.wat"] = "thing"
@@ -33,7 +34,7 @@ technically valid = haha hmm...
 	expectedMap["immaempty"] = ""
 	expectedMap["technically valid"] = "haha hmm..."
 
-	parsedMap, err := parse(configFile)
+	parsedMap, err := parseFile(configFile)
 	if err != nil {
 		t.Errorf("failed while parsing the file")
 	}
@@ -48,7 +49,7 @@ foo=bar=true
 `
 	configFile := strings.NewReader(configFileStr)
 
-	_, err = parse(configFile)
+	_, err = parseFile(configFile)
 	if err == nil {
 		t.Errorf("parse did not thrown an error when it was supposed to")
 	}
@@ -61,12 +62,46 @@ Something here with no equals to split on
 `
 	configFile := strings.NewReader(configFileStr)
 
-	_, err = parse(configFile)
+	_, err = parseFile(configFile)
 	if err == nil {
 		t.Errorf("parse did not thrown an error when it was supposed to")
 	}
 }
 
+func TestFlagOverrides(t *testing.T) {
+	var err error
+	configFileStr := `
+foo=bar
+asdf = 1234
+foo.wat =stuff
+immaempty=
+`
+	configFile := strings.NewReader(configFileStr)
+
+	expectedMap := make(ConfigMap)
+	expectedMap["foo"] = "bar"
+	expectedMap["asdf"] = "1234"
+	// expect to override the 'foo.wat' value with a cli flag
+	expectedMap["foo.wat"] = "iwasoverridden"
+	expectedMap["immaempty"] = ""
+
+	configMap, err := parseFile(configFile)
+	if err != nil {
+		t.Errorf("failed while parsing the file")
+	}
+
+	flagMap := SetupFlagOverrides(configMap)
+
+	err = flag.Set("foo.wat", "iwasoverridden")
+	if err != nil {
+		t.Errorf("failed to set cli flag override")
+	}
+
+	configMap = ParseFlags(configMap, flagMap)
+
+	validateMap(t, configMap, expectedMap)
+}
+
 func validateMap(t *testing.T, given map[string]string, expected map[string]string) {
 	if given == nil {
 		t.Errorf("given map was nil")