Merge pull request #5 from whutchinson98/cli-definition

Author: whutchinson98

Makefile

@@ -37,4 +37,4 @@ fmt:
 ## build: Build binary into bin/ directory
 .PHONY: build
 build:
-	go build -ldflags="-w -s" -o bin/app ./...
+	go build -ldflags="-w -s" -o bin ./...

cmd/main.go

@@ -1,8 +1,19 @@
 package main
 
-import "fmt"
+import (
+	"fmt"
+	"os"
+
+	"github.com/rog-golang-buddies/internal/parser"
+)
 
 func main() {
-	// Feel free to delete this file.
-	fmt.Println("Hello Gophers")
+	commands, flags, err := parser.ParseCliArguments(os.Args[1:])
+
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Printf("CLI Commands: %v\n", commands)
+	fmt.Printf("CLI Flags: %v\n", flags)
 }

internal/parser/parse_cli.go

@@ -0,0 +1,78 @@
+package parser
+
+import (
+	"fmt"
+	"strings"
+)
+
+func ParseCliArguments(arguments []string) ([]string, map[string]interface{}, error) {
+	var commands []string
+
+	flags := map[string]interface{}{}
+
+	flagsStarted := false
+	var lastValueWasFlag bool
+	var lastValueFlag string
+
+	for _, value := range arguments {
+		if !flagsStarted && !strings.Contains(value, "-") {
+			commands = append(commands, value)
+			continue
+		}
+
+		// Check if the string is a flag
+		var isFlag bool
+
+		if strings.Contains(value, "-") {
+			flagsStarted = true
+			isFlag = true
+		}
+
+		// add value to the last value flag
+		if lastValueWasFlag {
+			// The current value is also a flag so we just add true to the flags value
+			flag := strings.ReplaceAll(lastValueFlag, "-", "")
+
+			if flag == "" {
+				return nil, nil, fmt.Errorf("empty flag was passed in")
+			}
+
+			if flags[flag] != nil {
+				return nil, nil, fmt.Errorf("flag %v was set multiple times", flag)
+			}
+			if isFlag {
+				flags[flag] = true
+			} else {
+				flags[flag] = value
+			}
+			lastValueWasFlag = false
+			lastValueFlag = ""
+
+		} else {
+			// the last value was not a flag
+			// if this value is also not a flag the user entered in 2 values for a single flag
+			if !isFlag {
+				return nil, nil, fmt.Errorf("invalid number of parameters. Unexpected value %v", value)
+			}
+		}
+
+		// Used for next iteration
+		if isFlag {
+			lastValueFlag = value
+			lastValueWasFlag = true
+		}
+	}
+
+	if lastValueWasFlag {
+		flag := strings.ReplaceAll(lastValueFlag, "-", "")
+		if flag == "" {
+			return nil, nil, fmt.Errorf("empty flag was passed in")
+		}
+		if flags[flag] != nil {
+			return nil, nil, fmt.Errorf("flag %v was set multiple times", flag)
+		}
+		flags[flag] = true
+	}
+
+	return commands, flags, nil
+}

internal/parser/parse_cli_test.go

@@ -0,0 +1,101 @@
+package parser
+
+import (
+	"testing"
+)
+
+func TestParseCliArguments(t *testing.T) {
+
+	t.Run("Correctly gets commands", func(t *testing.T) {
+		commands, _, _ := ParseCliArguments([]string{"test_command1", "test_command2"})
+
+		if len(commands) != 2 {
+			t.Fatalf("Invalid command length. Expected %v got %v\n", 2, len(commands))
+		}
+
+		if commands[0] != "test_command1" {
+			t.Fatalf("Error in commands expected %v got %v\n", "test_command1", commands[0])
+		}
+
+		if commands[1] != "test_command2" {
+			t.Fatalf("Error in commands expected %v got %v\n", "test_command2", commands[1])
+		}
+	})
+
+	t.Run("Correctly creates flags that have values", func(t *testing.T) {
+		_, flags, _ := ParseCliArguments([]string{"test_command1", "--foo", "bar", "--baz", "foo"})
+
+		if len(flags) != 2 {
+			t.Fatalf("Invalid flags length. Expected %v got %v\n", 2, len(flags))
+		}
+
+		if flags["foo"] != "bar" {
+			t.Fatalf("Error in flags expected %v got %v\n", "bar", flags["foo"])
+		}
+
+		if flags["baz"] != "foo" {
+			t.Fatalf("Error in flags expected %v got %v\n", "foo", flags["baz"])
+		}
+	})
+
+	t.Run("Correctly creates flags that are booleans", func(t *testing.T) {
+		_, flags, _ := ParseCliArguments([]string{"test_command1", "--foo", "--baz", "foo"})
+
+		if len(flags) != 2 {
+			t.Fatalf("Invalid flags length. Expected %v got %v\n", 2, len(flags))
+		}
+
+		if flags["foo"] != true {
+			t.Fatalf("Error in flags expected %v got %v\n", true, flags["foo"])
+		}
+
+		if flags["baz"] != "foo" {
+			t.Fatalf("Error in flags expected %v got %v\n", "foo", flags["baz"])
+		}
+	})
+	t.Run("Correctly errors if you enter too many values for a given flag", func(t *testing.T) {
+		_, _, err := ParseCliArguments([]string{"test_command1", "--foo", "value1", "value2", "--bar"})
+
+		if err == nil {
+			t.Fatalf("Error was expected but not received")
+		}
+
+		if err.Error() != "invalid number of parameters. Unexpected value value2" {
+			t.Fatalf("Error message incorrect. Expected \"%v\" got \"%v\"", "invalid number of parameters. Unexpected value value2", err.Error())
+		}
+	})
+	t.Run("Correctly errors if you try to pass in the same flag twice", func(t *testing.T) {
+		_, _, err := ParseCliArguments([]string{"test_command1", "--foo", "value1", "--foo", "--bar"})
+
+		if err == nil {
+			t.Fatalf("Error was expected but not received")
+		}
+
+		if err.Error() != "flag foo was set multiple times" {
+			t.Fatalf("Error message incorrect. Expected \"%v\" got \"%v\"", "flag foo was set multiple times", err.Error())
+		}
+	})
+	t.Run("Correctly errors if you try to pass in the same flag twice, duplicate flag is the last value", func(t *testing.T) {
+		_, _, err := ParseCliArguments([]string{"test_command1", "--foo", "value1", "--bar", "--foo"})
+
+		if err == nil {
+			t.Fatalf("Error was expected but not received")
+		}
+
+		if err.Error() != "flag foo was set multiple times" {
+			t.Fatalf("Error message incorrect. Expected \"%v\" got \"%v\"", "flag foo was set multiple times", err.Error())
+		}
+	})
+	t.Run("Correctly errors if you pass in empty -", func(t *testing.T) {
+		_, _, err := ParseCliArguments([]string{"test_command1", "--", "value1", "--bar", "--foo"})
+
+		if err == nil {
+			t.Fatalf("Error was expected but not received")
+		}
+
+		if err.Error() != "empty flag was passed in" {
+			t.Fatalf("Error message incorrect. Expected \"%v\" got \"%v\"", "empty flag was passed in", err.Error())
+		}
+	})
+
+}