feature plugin dependency management

assets/app/main_desktop.dart

@@ -0,0 +1,10 @@
+import 'package:flutter/foundation.dart'
+    show debugDefaultTargetPlatformOverride;
+import 'package:flutter/material.dart';
+
+import './main.dart';
+
+void main() {
+  debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
+  runApp(MyApp());
+}

assets/plugin/README.md.tmpl

@@ -0,0 +1,17 @@
+# {{.pluginName}}
+
+This Go package implements the host-side of the Flutter [{{.pluginName}}](https://{{.urlVSCRepo}}) plugin.
+
+## Usage
+
+Import as:
+
+```go
+import {{.pluginName}} "{{.urlVSCRepo}}/go"
+```
+
+Then add the following option to your go-flutter [application options](https://github.com/go-flutter-desktop/go-flutter/wiki/Plugin-info):
+
+```go
+flutter.AddPlugin(&{{.pluginName}}.{{.structName}}{}),
+```

assets/plugin/import.go.tmpl.tmpl

@@ -0,0 +1,13 @@
+package main
+
+// DO NOT EDIT, this file is generated by hover at compile-time for the {{.pluginName}} plugin.
+
+import (
+	flutter "github.com/go-flutter-desktop/go-flutter"
+	{{.pluginName}} "{{.urlVSCRepo}}/go"
+)
+
+func init() {
+	// Only the init function can be tweaked by plugin maker.
+	options = append(options, flutter.AddPlugin(&{{.pluginName}}.{{.structName}}{}))
+}

assets/plugin/plugin.go.tmpl

@@ -0,0 +1,24 @@
+package {{.pluginName}}
+
+import (
+	flutter "github.com/go-flutter-desktop/go-flutter"
+	"github.com/go-flutter-desktop/go-flutter/plugin"
+)
+
+const channelName = "{{.pluginName}}"
+
+// {{.structName}} implements flutter.Plugin and handles method.
+type {{.structName}} struct{}
+
+var _ flutter.Plugin = &{{.structName}}{} // compile-time type check
+
+// InitPlugin initializes the plugin.
+func (p *{{.structName}}) InitPlugin(messenger plugin.BinaryMessenger) error {
+	channel := plugin.NewMethodChannel(messenger, channelName, plugin.StandardMethodCodec{})
+	channel.HandleFunc("getPlatformVersion", p.handlePlatformVersion)
+	return nil
+}
+
+func (p *{{.structName}}) handlePlatformVersion(arguments interface{}) (reply interface{}, err error) {
+	return "go-flutter " + flutter.PlatformVersion, nil
+}

cmd/build.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 
 	"github.com/go-flutter-desktop/hover/internal/enginecache"
+	"github.com/go-flutter-desktop/hover/internal/fileutils"
 	"github.com/go-flutter-desktop/hover/internal/log"
 	"github.com/go-flutter-desktop/hover/internal/versioncheck"
 	"github.com/hashicorp/go-version"
@@ -118,6 +119,31 @@ var buildWindowsCmd = &cobra.Command{
 	},
 }
 
+// checkForMainDesktop checks and adds the lib/main_desktop.dart dart entry
+// point if needed
+func checkForMainDesktop() {
+	if buildTarget != "lib/main_desktop.dart" {
+		return
+	}
+	_, err := os.Stat("lib/main_desktop.dart")
+	if os.IsNotExist(err) {
+		log.Warnf("Target file \"lib/main_desktop.dart\" not found.")
+		log.Warnf("Let hover add the \"lib/main_desktop.dart\" file? ")
+		if askForConfirmation() {
+			fileutils.CopyAsset("app/main_desktop.dart", filepath.Join("lib", "main_desktop.dart"), assetsBox)
+			log.Infof("Target file \"lib/main_desktop.dart\" has been created.")
+			log.Infof("       Depending on your project, you might want to tweak it.")
+			return
+		}
+		log.Printf("You can define a custom traget by using the %s flag.", log.Au().Magenta("--target"))
+		os.Exit(1)
+	}
+	if err != nil {
+		log.Errorf("Failed to stat lib/main_desktop.dart: %v\n", err)
+		os.Exit(1)
+	}
+}
+
 func outputDirectoryPath(targetOS string) string {
 	outputDirectoryPath, err := filepath.Abs(filepath.Join(buildPath, "build", "outputs", targetOS))
 	if err != nil {
@@ -253,6 +279,7 @@ func dockerBuild(projectName string, targetOS string, vmArguments []string) {
 }
 
 func build(projectName string, targetOS string, vmArguments []string) {
+	checkForMainDesktop()
 	crossCompile = targetOS != runtime.GOOS
 	buildDocker = crossCompile || buildDocker
 
@@ -301,6 +328,14 @@ func build(projectName string, targetOS string, vmArguments []string) {
 		trackWidgetCreation = "--track-widget-creation"
 	}
 
+	// must be run before `flutter build bundle`
+	// because `build bundle` will update the file timestamp
+	runPluginGet, err := shouldRunPluginGet()
+	if err != nil {
+		log.Errorf("Failed to check if plugin get should be run: %v.\n", err)
+		os.Exit(1)
+	}
+
 	cmdFlutterBuild := exec.Command(flutterBin, "build", "bundle",
 		"--asset-dir", filepath.Join(outputDirectoryPath(targetOS), "flutter_assets"),
 		"--target", buildTarget,
@@ -318,6 +353,16 @@ func build(projectName string, targetOS string, vmArguments []string) {
 		}
 	}
 
+	if runPluginGet {
+		log.Printf("listing available plugins:")
+		if hoverPluginGet(true) {
+			log.Infof(fmt.Sprintf("run `%s`? ", log.Au().Magenta("hover plugins get")))
+			if askForConfirmation() {
+				hoverPluginGet(false)
+			}
+		}
+	}
+
 	var engineFile string
 	switch targetOS {
 	case "darwin":

cmd/common.go

@@ -3,22 +3,31 @@ package cmd
 import (
 	"bufio"
 	"encoding/xml"
+	"fmt"
 	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
+	"runtime"
 	"strings"
+	"time"
 
 	"github.com/go-flutter-desktop/hover/internal/log"
+	homedir "github.com/mitchellh/go-homedir"
+	"github.com/pkg/errors"
 	"gopkg.in/yaml.v2"
 )
 
 var (
 	goBin      string
 	flutterBin string
 	dockerBin  string
+	gitBin     string
 )
 
+// initBinaries is used to ensure go and flutter exec are found in the
+// user's path
 func initBinaries() {
 	var err error
 	goAvailable := false
@@ -44,58 +53,78 @@ func initBinaries() {
 		log.Errorf("Failed to lookup 'flutter' executable. Please install flutter.\nhttps://flutter.dev/docs/get-started/install")
 		os.Exit(1)
 	}
+	gitBin, err = exec.LookPath("git")
+	if err != nil {
+		log.Warnf("Failed to lookup 'git' executable.")
+	}
 }
 
-// PubSpec  basic model pubspec
+// PubSpec contains the parsed contents of pubspec.yaml
 type PubSpec struct {
 	Name         string
 	Description  string
 	Version      string
 	Author       string
 	Dependencies map[string]interface{}
+	Flutter      map[string]interface{}
 }
 
 var pubspec = PubSpec{}
 
+// getPubSpec returns the working directory pubspec.yaml as a PubSpec
 func getPubSpec() PubSpec {
-	{
-		if pubspec.Name == "" {
-			file, err := os.Open("pubspec.yaml")
-			if err != nil {
-				if os.IsNotExist(err) {
-					log.Errorf("Error: No pubspec.yaml file found.")
-					goto Fail
-				}
-				log.Errorf("Failed to open pubspec.yaml: %v", err)
-				os.Exit(1)
-			}
-			defer file.Close()
-
-			err = yaml.NewDecoder(file).Decode(&pubspec)
-			if err != nil {
-				log.Errorf("Failed to decode pubspec.yaml: %v", err)
-				goto Fail
-			}
-			if _, exists := pubspec.Dependencies["flutter"]; !exists {
-				log.Errorf("Missing 'flutter' in pubspec.yaml dependencies list.")
-				goto Fail
-			}
+	if pubspec.Name == "" {
+		pub, err := readPubSpecFile("pubspec.yaml")
+		if err != nil {
+			log.Errorf("%v", err)
+			log.Errorf("This command should be run from the root of your Flutter project.")
+			os.Exit(1)
 		}
+		pubspec = *pub
+	}
+	return pubspec
+}
 
-		return pubspec
+// readPubSpecFile reads a .yaml file at a path and return a correspond
+// PubSpec struct
+func readPubSpecFile(pubSpecPath string) (*PubSpec, error) {
+	file, err := os.Open(pubSpecPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, errors.Wrap(err, "Error: No pubspec.yaml file found")
+		}
+		return nil, errors.Wrap(err, "Failed to open pubspec.yaml")
 	}
+	defer file.Close()
 
-Fail:
-	log.Errorf("This command should be run from the root of your Flutter project.")
-	os.Exit(1)
-	return PubSpec{}
+	var pub PubSpec
+	err = yaml.NewDecoder(file).Decode(&pub)
+	if err != nil {
+		return nil, errors.Wrap(err, "Failed to decode pubspec.yaml")
+	}
+	// avoid checking for the flutter dependencies for out of ws directories
+	if pubSpecPath != "pubspec.yaml" {
+		return &pub, nil
+	}
+	if _, exists := pub.Dependencies["flutter"]; !exists {
+		return nil, errors.New(fmt.Sprintf("Missing `flutter` in %s dependencies list", pubSpecPath))
+	}
+	return &pub, nil
 }
 
 // assertInFlutterProject asserts this command is executed in a flutter project
 func assertInFlutterProject() {
 	getPubSpec()
 }
 
+// assertInFlutterPluginProject asserts this command is executed in a flutter plugin project
+func assertInFlutterPluginProject() {
+	if _, ok := getPubSpec().Flutter["plugin"]; !ok {
+		log.Errorf("The directory doesn't appear to contain a plugin package.\nTo create a new plugin, first run `%s`, then run `%s`.", log.Au().Magenta("flutter create --template=plugin"), log.Au().Magenta("hover init-plugin"))
+		os.Exit(1)
+	}
+}
+
 func assertHoverInitialized() {
 	_, err := os.Stat(buildPath)
 	if os.IsNotExist(err) {
@@ -111,6 +140,7 @@ func assertHoverInitialized() {
 	}
 }
 
+// hoverMigration migrates from old hover buildPath directory to the new one ("desktop" -> "go")
 func hoverMigration() bool {
 	oldBuildPath := "desktop"
 	file, err := os.Open(filepath.Join(oldBuildPath, "go.mod"))
@@ -138,7 +168,7 @@ func hoverMigration() bool {
 
 // askForConfirmation asks the user for confirmation.
 func askForConfirmation() bool {
-	log.Printf("[y/N]: ")
+	fmt.Print(log.Au().Bold(log.Au().Cyan("hover: ")).String() + "[y/N]? ")
 	in := bufio.NewReader(os.Stdin)
 	s, err := in.ReadString('\n')
 	if err != nil {
@@ -197,3 +227,90 @@ func androidOrganizationName() string {
 	}
 	return orgName
 }
+
+var camelcaseRegex = regexp.MustCompile("(^[A-Za-z])|_([A-Za-z])")
+
+// toCamelCase take a snake_case string and converts it to camelcase
+func toCamelCase(str string) string {
+	return camelcaseRegex.ReplaceAllStringFunc(str, func(s string) string {
+		return strings.ToUpper(strings.Replace(s, "_", "", -1))
+	})
+}
+
+// initializeGoModule uses the golang binary to initialize the go module
+func initializeGoModule(projectPath string) {
+	wd, err := os.Getwd()
+	if err != nil {
+		log.Errorf("Failed to get working dir: %v\n", err)
+		os.Exit(1)
+	}
+
+	cmdGoModInit := exec.Command(goBin, "mod", "init", projectPath+"/"+buildPath)
+	cmdGoModInit.Dir = filepath.Join(wd, buildPath)
+	cmdGoModInit.Env = append(os.Environ(),
+		"GO111MODULE=on",
+	)
+	cmdGoModInit.Stderr = os.Stderr
+	cmdGoModInit.Stdout = os.Stdout
+	err = cmdGoModInit.Run()
+	if err != nil {
+		log.Errorf("Go mod init failed: %v\n", err)
+		os.Exit(1)
+	}
+
+	cmdGoModTidy := exec.Command(goBin, "mod", "tidy")
+	cmdGoModTidy.Dir = filepath.Join(wd, buildPath)
+	log.Infof("You can add the '%s' directory to git.", cmdGoModTidy.Dir)
+	cmdGoModTidy.Env = append(os.Environ(),
+		"GO111MODULE=on",
+	)
+	cmdGoModTidy.Stderr = os.Stderr
+	cmdGoModTidy.Stdout = os.Stdout
+	err = cmdGoModTidy.Run()
+	if err != nil {
+		log.Errorf("Go mod tidy failed: %v\n", err)
+		os.Exit(1)
+	}
+}
+
+// findPubcachePath returns the absolute path for the pub-cache or an error.
+func findPubcachePath() (string, error) {
+	var path string
+	switch runtime.GOOS {
+	case "darwin", "linux":
+		home, err := homedir.Dir()
+		if err != nil {
+			return "", errors.Wrap(err, "failed to resolve user home dir")
+		}
+		path = filepath.Join(home, ".pub-cache")
+	case "windows":
+		path = filepath.Join(os.Getenv("APPDATA"), "Pub", "Cache")
+	}
+	return path, nil
+}
+
+// shouldRunPluginGet checks if the pubspec.yaml file is older than the
+// .packages file, if it is the case, prompt the user for a hover plugin get.
+func shouldRunPluginGet() (bool, error) {
+	file1Info, err := os.Stat("pubspec.yaml")
+	if err != nil {
+		return false, err
+	}
+
+	file2Info, err := os.Stat(".packages")
+	if err != nil {
+		if os.IsNotExist(err) {
+			return true, nil
+		}
+		return false, err
+	}
+	modTime1 := file1Info.ModTime()
+	modTime2 := file2Info.ModTime()
+
+	diff := modTime1.Sub(modTime2)
+
+	if diff > (time.Duration(0) * time.Second) {
+		return true, nil
+	}
+	return false, nil
+}