initial blorg build implementation

main.go

@@ -3,24 +3,24 @@ package main
 import (
 	"flag"
 	"fmt"
+	"io/fs"
 	"os"
+	"path/filepath"
 )
 
-// TODO consider using cobra or something else to make cli more declarative
-// and get a better ux out of the box
 func main() {
-
+	// TODO consider using cobra or something else to make cli more declarative
+	// and get a better ux out of the box
 	initCmd := flag.NewFlagSet("init", flag.ExitOnError)
-	buildCmd := flag.NewFlagSet("build", flag.ExitOnError)
 	newCmd := flag.NewFlagSet("new", flag.ExitOnError)
 	serveCmd := flag.NewFlagSet("serve", flag.ExitOnError)
 
 	if len(os.Args) < 2 {
-		printAndExit()
+		// TODO print usage
+		exit("expected subcommand")
 	}
 
 	switch os.Args[1] {
-
 	case "init":
 		initCmd.Parse(os.Args[2:])
 		// get working directory
@@ -29,14 +29,7 @@ func main() {
 		// copy over default files
 		fmt.Println("not implemented yet")
 	case "build":
-		buildCmd.Parse(os.Args[2:])
-		// delete target if exist
-		// create target dir
-		// walk through files in src dir
-		// copy them over to target
-		// (later render templates and org)
-		// (later minify)
-		fmt.Println("not implemented yet")
+		build()
 	case "new":
 		newCmd.Parse(os.Args[2:])
 		// prompt for title
@@ -52,12 +45,57 @@ func main() {
 		serveCmd.Parse(os.Args[2:])
 		fmt.Println("not implemented yet")
 	default:
-		printAndExit()
+		// TODO print usage
+		exit("unknown subcommand")
 	}
+
 }
 
-func printAndExit() {
-	// TODO print usage
-	fmt.Println("expected a subcommand")
+// Read the files in src/ render them and copy the result to target/
+func build() {
+	// fail if no src dir
+	_, err := os.ReadDir("src")
+	if os.IsNotExist(err) {
+		exit("missing src/ directory")
+	} else if err != nil {
+		panic("couldn't read src")
+	}
+
+	// clear previous target contents
+	const FILE_MODE = 0777
+	os.RemoveAll("target")
+	os.Mkdir("target", FILE_MODE)
+
+	// render each source file and copy it over to target
+	filepath.WalkDir("src", func(path string, entry fs.DirEntry, err error) error {
+		subpath, _ := filepath.Rel("src", path)
+		targetSubpath := filepath.Join("target", subpath)
+
+		if entry.IsDir() {
+			os.MkdirAll(targetSubpath, FILE_MODE)
+		} else {
+			// read file contents
+			data, err := os.ReadFile(path)
+			if err != nil {
+				panic(fmt.Sprintf("failed to load %s", targetSubpath))
+			}
+
+			// TODO render templates and org
+			// TODO minify
+
+			// write the file contents over to target at the same location
+			err = os.WriteFile(targetSubpath, data, FILE_MODE)
+			if err != nil {
+				panic(fmt.Sprintf("failed to load %s", targetSubpath))
+			}
+			fmt.Printf("wrote %v", targetSubpath)
+		}
+
+		return nil
+	})
+}
+
+func exit(message string) {
+	fmt.Println(message)
 	os.Exit(1)
 }