Implement cli argument for file path, path validation, file type validation

cmd/zona/main.go

@@ -1,9 +1,57 @@
 package main
 
 import (
+	"errors"
+	"flag"
 	"fmt"
+	"os"
+
+	"github.com/ficcdaf/zona/internal/util"
 )
 
-func main() {
-	fmt.Println("Hello, world!")
+// validateFile checks whether a given path
+// is a valid file && matches an expected extension
+func validateFile(path, ext string) bool {
+	return (util.CheckExtension(path, ext) == nil) && (util.PathIsValid(path, true))
+}
+
+func main() {
+	mdPath := flag.String("file", "", "Path to the markdown file.")
+	flag.Parse()
+	if *mdPath == "" {
+		// no flag provided, check for positional argument instead
+		n := flag.NArg()
+		var e error
+		switch n {
+		case 1:
+			// we read the positional arg
+			arg := flag.Arg(0)
+			// mdPath wants a pointer so we get arg's address
+			mdPath = &arg
+		case 0:
+			// in case of no flag and no arg, we fail
+			e = errors.New("Required argument missing!")
+		default:
+			// more args than expected is also fail
+			e = errors.New("Unexpected arguments!")
+		}
+		if e != nil {
+			fmt.Printf("Error: %s\n", e.Error())
+			os.Exit(1)
+		}
+
+	}
+	if !validateFile(*mdPath, ".md") {
+		fmt.Println("File validation failed!")
+		os.Exit(1)
+	}
+
+	file, err := os.Open(*mdPath)
+	if err != nil {
+		fmt.Println("Error reading file:", err)
+		os.Exit(1)
+	}
+	defer file.Close()
+
+	fmt.Println("File opened :)")
 }

go.mod

@@ -1,3 +1,5 @@
 module github.com/ficcdaf/zona
 
 go 1.23.2
+
+require github.com/gomarkdown/markdown v0.0.0-20240930133441-72d49d9543d8 // indirect

internal/convert/mdToHtml.go

@@ -0,0 +1,22 @@
+package convert
+
+import (
+	"github.com/gomarkdown/markdown"
+	"github.com/gomarkdown/markdown/html"
+	"github.com/gomarkdown/markdown/parser"
+)
+
+// This function takes a Markdown document and returns an HTML document.
+func MdToHTML(md []byte) ([]byte, error) {
+	// create parser with extensions
+	extensions := parser.CommonExtensions | parser.AutoHeadingIDs | parser.NoEmptyLineBeforeBlock
+	p := parser.NewWithExtensions(extensions)
+	doc := p.Parse(md)
+
+	// build HTML renderer
+	htmlFlags := html.CommonFlags | html.HrefTargetBlank
+	opts := html.RendererOptions{Flags: htmlFlags}
+	renderer := html.NewRenderer(opts)
+
+	return markdown.Render(doc, renderer), nil
+}

internal/util/path.go

@@ -0,0 +1,33 @@
+// Package util provides general utilities.
+package util
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+)
+
+// CheckExtension checks if the file located at path (string)
+// matches the provided extension type
+func CheckExtension(path, ext string) error {
+	if filepath.Ext(path) == ext {
+		return nil
+	} else {
+		return errors.New("Invalid extension.")
+	}
+}
+
+// PathIsValid checks if a path is valid.
+// If requireFile is set, directories are not considered valid.
+func PathIsValid(path string, requireFile bool) bool {
+	s, err := os.Stat(path)
+	if os.IsNotExist(err) {
+		return false
+	} else if requireFile {
+		fmt.Printf("Directory status: %s\n", strconv.FormatBool(s.IsDir()))
+		return !s.IsDir()
+	}
+	return err == nil
+}

test/in.md

@@ -0,0 +1,3 @@
+# My amazing markdown file!
+
+I can _even_ do **this**!

zona

@@ -0,0 +1 @@
+bin/zona