Implement doctor command

Author: juho05

README.md

@@ -142,6 +142,11 @@ Display help about a specific command:
 codegame help <cmd>
 ```
 
+Check for missing dependencies and misconfigurations:
+```
+codegame doctor
+```
+
 ## Installation
 
 ### Windows

cmd/doctor.go

@@ -0,0 +1,134 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"runtime"
+
+	"github.com/Bananenpro/cli"
+	"github.com/spf13/cobra"
+)
+
+type doctorRule interface {
+	Check() bool
+	ErrMessage() string
+	SuccessMessage() string
+}
+
+type doctorRuleInactive struct{}
+
+func (d doctorRuleInactive) Check() bool {
+	return true
+}
+
+func (d doctorRuleInactive) ErrMessage() string {
+	return ""
+}
+
+func (d doctorRuleInactive) SuccessMessage() string {
+	return ""
+}
+
+type doctorRuleTool struct {
+	names   []string
+	message string
+}
+
+func newDoctorRuleTool(message string, names ...string) doctorRule {
+	return doctorRuleTool{
+		names:   names,
+		message: message,
+	}
+}
+
+func newDoctorRuleToolWithCondition(message string, active bool, names ...string) doctorRule {
+	if !active {
+		return doctorRuleInactive{}
+	}
+	return doctorRuleTool{
+		names:   names,
+		message: message,
+	}
+}
+
+func (d doctorRuleTool) Check() bool {
+	for _, n := range d.names {
+		if _, err := exec.LookPath(n); err == nil {
+			return true
+		}
+	}
+	return false
+}
+
+func (d doctorRuleTool) ErrMessage() string {
+	return d.message
+}
+
+func (d doctorRuleTool) SuccessMessage() string {
+	for _, n := range d.names {
+		if _, err := exec.LookPath(n); err == nil {
+			return fmt.Sprintf("`%s` is installed.", n)
+		}
+	}
+	panic("SuccessMessage() called but tool is not installed")
+}
+
+var installDir = "/usr/local/bin"
+
+func init() {
+	if runtime.GOOS == "windows" {
+		installDir = os.Getenv("HOME") + "\\AppData\\Local\\Programs\\codegame-cli"
+	}
+}
+
+type doctorCategory struct {
+	name  string
+	rules []doctorRule
+}
+
+var doctorRules = []doctorCategory{
+	{name: "CLI", rules: []doctorRule{
+		newDoctorRuleTool("`codegame` is not in PATH. If you have installed codegame-cli in a custom install directory, make sure to add it to the PATH environment variable. Otherwise, manually add "+installDir+" to the PATH environment variable.", "codegame"),
+		newDoctorRuleToolWithCondition("Either curl or wget must be installed to use `codegame upgrade`.", runtime.GOOS != "windows", "curl", "wget"),
+	}},
+	{name: "C#", rules: []doctorRule{
+		newDoctorRuleTool("`dotnet` must be installed to develop CodeGame applications using C#. Install it from https://dotnet.microsoft.com/en-us/download.", "dotnet"),
+	}},
+	{name: "Go", rules: []doctorRule{
+		newDoctorRuleTool("`go` must be installed to develop CodeGame applications using the Go programming language. Install it from https://go.dev.", "go"),
+	}},
+	{name: "Java", rules: []doctorRule{
+		newDoctorRuleTool("`java` must be installed to develop CodeGame applications using Java. Install it from https://adoptium.net.", "java"),
+		newDoctorRuleTool("`mvn` must be installed to develop CodeGame applications using Java. Download it from https://maven.apache.org/download.cgi and follow the instructions at https://maven.apache.org/install.html.", "mvn"),
+	}},
+	{name: "JavaScript", rules: []doctorRule{
+		newDoctorRuleTool("`npm` must be installed to develop CodeGame applications using JavaScript or TypeScript. Install it from https://nodejs.org.", "npm"),
+		newDoctorRuleTool("`npx` must be installed to run TypeScript or browser based CodeGame applications. Install it using `npm install -g npx`.", "npx"),
+	}},
+}
+
+// doctorCmd represents the doctor command
+var doctorCmd = &cobra.Command{
+	Use:   "doctor",
+	Short: "Check for missing dependencies and misconfigurations.",
+	Run: func(_ *cobra.Command, _ []string) {
+		for _, category := range doctorRules {
+			cli.PrintColor(cli.Cyan, "%s:", category.name)
+			for _, r := range category.rules {
+				if _, ok := r.(doctorRuleInactive); ok {
+					continue
+				}
+				if r.Check() {
+					cli.PrintColor(cli.Green, "  √ %s", r.SuccessMessage())
+				} else {
+					cli.PrintColor(cli.Red, "  x %s", r.ErrMessage())
+				}
+			}
+		}
+	},
+}
+
+func init() {
+	rootCmd.AddCommand(doctorCmd)
+}