Shell feature (#44)

Resolves #37: adds a shell tab where the user can write mongo shell
scripts and execute them.

internal/app/app.go

@@ -25,6 +25,7 @@ type EnvironmentInfo struct {
 
 	HasMongoExport bool `json:"hasMongoExport"`
 	HasMongoDump   bool `json:"hasMongoDump"`
+	HasMongoShell  bool `json:"hasMongoShell"`
 
 	HomeDirectory     string `json:"homeDirectory"`
 	DataDirectory     string `json:"dataDirectory"`
@@ -49,6 +50,9 @@ func NewApp(version string) *App {
 	_, err = exec.LookPath("mongoexport")
 	a.Env.HasMongoExport = err == nil
 
+	_, err = exec.LookPath("mongosh")
+	a.Env.HasMongoShell = err == nil
+
 	a.Env.HomeDirectory, err = os.UserHomeDir()
 	if err != nil {
 		panic(errors.New("encountered an error while getting home directory"))

internal/app/host_shell.go

@@ -0,0 +1,105 @@
+package app
+
+import (
+	"fmt"
+	"net/url"
+	"os"
+	"os/exec"
+	"path"
+
+	"github.com/google/uuid"
+	"github.com/wailsapp/wails/v2/pkg/runtime"
+)
+
+type ExecuteShellScriptResult struct {
+	Output           string `json:"output"`
+	Status           int    `json:"status"`
+	ErrorTitle       string `json:"errorTitle"`
+	ErrorDescription string `json:"errorDescription"`
+}
+
+func (a *App) ExecuteShellScript(hostKey, dbKey, collKey, script string) (result ExecuteShellScriptResult) {
+	if !a.Env.HasMongoShell {
+		result.ErrorTitle = "mongosh not found"
+		result.ErrorDescription = "The mongosh executable is required to run a shell script. Please see https://www.mongodb.com/docs/mongodb-shell/install/"
+		return
+	}
+
+	hosts, err := a.Hosts()
+	if err != nil {
+		result.ErrorTitle = "Could not get hosts"
+		result.ErrorDescription = err.Error()
+		return
+	}
+
+	host, hostFound := hosts[hostKey]
+	if !hostFound {
+		result.ErrorTitle = "The specified host does not seem to exist"
+		return
+	}
+
+	id, err := uuid.NewRandom()
+	if err != nil {
+		runtime.LogErrorf(a.ctx, "Shell: failed to generate a UUID: %s", err.Error())
+		result.ErrorTitle = "Could not generate UUID"
+		result.ErrorDescription = err.Error()
+		return
+	}
+
+	dirname := path.Join(a.Env.DataDirectory, "Shell Scripts")
+	fname := path.Join(dirname, fmt.Sprintf("%s.mongosh.js", id.String()))
+
+	if err := os.MkdirAll(dirname, os.ModePerm); err != nil {
+		runtime.LogWarningf(a.ctx, "Shell: failed to mkdir %s", err.Error())
+		result.ErrorTitle = "Could not create temporary directory"
+		result.ErrorDescription = err.Error()
+		return
+	}
+
+	scriptHeader := fmt.Sprintf("// Namespace: %s.%s\n", dbKey, collKey)
+
+	if dbKey != "" {
+		url, err := url.Parse(host.URI)
+		if err != nil {
+			runtime.LogWarningf(a.ctx, "Shell: failed to parse host URI %s: %s", host.URI, err.Error())
+			result.ErrorTitle = "Could parse host URI"
+			result.ErrorDescription = err.Error()
+			return
+		}
+
+		url.Path = "/" + dbKey
+		scriptHeader = scriptHeader + fmt.Sprintf("db = connect('%s');\n", url.String())
+	}
+
+	if collKey != "" {
+		scriptHeader = scriptHeader + fmt.Sprintf("coll = db.getCollection('%s');\n", collKey)
+	}
+
+	scriptHeader = scriptHeader + "\n// Start of user script\n"
+	script = scriptHeader + script
+
+	if err := os.WriteFile(fname, []byte(script), os.ModePerm); err != nil {
+		runtime.LogWarningf(a.ctx, "Shell: failed to write script to %s", err.Error())
+		result.ErrorTitle = "Could not create temporary script file"
+		result.ErrorDescription = err.Error()
+		return
+	}
+
+	cmd := exec.Command("mongosh", "--file", fname, host.URI)
+	stdout, err := cmd.Output()
+
+	if exiterr, ok := err.(*exec.ExitError); ok {
+		result.Status = exiterr.ExitCode()
+	} else if err != nil {
+		runtime.LogWarningf(a.ctx, "Shell: failed to execute: mongosh --file %s: %s", fname, err.Error())
+		result.ErrorTitle = "Could not execute script"
+		result.ErrorDescription = err.Error()
+		return
+	} else {
+		result.Status = 0
+	}
+
+	os.Remove(fname)
+	result.Output = string(stdout)
+	return
+}