Support watching for modified npm packages

Allow array of build configs.

linker.go

@@ -0,0 +1,123 @@
+package main
+
+import (
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/otiai10/copy"
+	"github.com/radovskyb/watcher"
+	"github.com/tidwall/gjson"
+)
+
+func link(from, to string) chan struct{} {
+	requestBuildCh := make(chan struct{})
+
+	// Load package.json in destination.
+	destPkg := readFileContent(filepath.Join(to, "package.json"))
+	depsRaw := gjson.Get(destPkg, "dependencies").Map()
+	deps := map[string]bool{}
+	for k := range depsRaw {
+		deps[k] = true
+	}
+
+	packages := map[string]string{}
+	packageFiles := findFiles(from, "package.json")
+
+	for i := range packageFiles {
+		content := readFileContent(packageFiles[i])
+		name := gjson.Get(content, "name").String()
+
+		if deps[name] {
+			packages[name] = filepath.Dir(packageFiles[i])
+		}
+	}
+
+	go func() {
+		w := watcher.New()
+		w.SetMaxEvents(1)
+		w.FilterOps(watcher.Write, watcher.Rename, watcher.Move, watcher.Create, watcher.Remove)
+
+		if err := w.AddRecursive(from); err != nil {
+			fmt.Println(err.Error())
+			os.Exit(1)
+		}
+
+		go func() {
+			for {
+				select {
+				case event := <-w.Event:
+					fmt.Printf("File %s changed\n", event.Path)
+					for k, v := range packages {
+						if strings.HasPrefix(event.Path, v) {
+							src := filepath.Dir(event.Path)
+							dest := filepath.Join(to, "node_modules", k)
+							fmt.Printf("Copying %s to %s\n", src, dest)
+							err := copy.Copy(src, dest, copy.Options{
+								Skip: func(src string) (bool, error) {
+									ok, _ := filepath.Match("*.js", filepath.Base(src))
+									if ok && !strings.Contains(src, "node_modules") {
+										return false, nil
+									}
+
+									return true, nil
+								},
+								Sync: true,
+							})
+
+							if err != nil {
+								fmt.Printf("Failed to copy %s: %v\n", k, err)
+							}
+
+							requestBuildCh <- struct{}{}
+						}
+					}
+				case err := <-w.Error:
+					fmt.Println(err.Error())
+				case <-w.Closed:
+					return
+				}
+			}
+		}()
+
+		fmt.Printf("Watching packages in %s\n", from)
+
+		if err := w.Start(time.Millisecond * 100); err != nil {
+			fmt.Println(err.Error())
+		}
+	}()
+
+	return requestBuildCh
+}
+
+func findFiles(root, name string) []string {
+	paths := []string{}
+
+	filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return nil
+		}
+
+		if !d.IsDir() && filepath.Base(path) == name && !strings.Contains(path, "node_modules") {
+			paths = append(paths, path)
+		}
+
+		return nil
+	})
+
+	return paths
+}
+
+func readFileContent(path string) string {
+	pkgData, err := os.ReadFile(path)
+
+	if err != nil {
+		fmt.Printf("%+v\n", err)
+		os.Exit(1)
+	}
+
+	return string(pkgData)
+}