✨ Introduce optional strict mode for config (#252)

This adds a strict mode using toml marshalling to ensure that all fields in a config file are present and correctly typed. This is being introduced as an opt-in feature using the `strict_mode` flag.

Co-authored-by: Copilot <[email protected]>

Author: randomdude16671

configurator/configurator.go

@@ -1,6 +1,7 @@
 package configurator
 
 import (
+	"errors"
 	"fmt"
 	"strings"
 
@@ -12,7 +13,7 @@ import (
 )
 
 type Configurator interface {
-	GetConfig() (model.Config, error)
+	GetConfig() (model.Config, error) // Since error is an interface, we use it here to return a single variable instead of multiple variables (configError holds 2 strings, human and err)
 }
 
 type RealConfigurator struct {
@@ -21,6 +22,20 @@ type RealConfigurator struct {
 	runtime runtimewrap.Runtime
 }
 
+// Helper for consolidation of error into a single structure
+type ConfigError struct {
+	Err          string // Load the (DecodeError/StrictMissingError).Error() into this
+	HumanDetails string // Load the (DecodeError/StrictMissingError).String() into this
+}
+
+func (ce *ConfigError) Error() string {
+	return ce.Err // Return the error
+}
+
+func (ce *ConfigError) Human() string {
+	return ce.HumanDetails // Return the string
+}
+
 func NewConfigurator(os oswrap.Os, path pathwrap.Path, runtime runtimewrap.Runtime) Configurator {
 	return &RealConfigurator{os, path, runtime}
 }
@@ -39,20 +54,39 @@ func (c *RealConfigurator) fullImportPath(homeDir, importPath string) (string, e
 
 func (c *RealConfigurator) getConfigFileFromUserConfigDir() (model.Config, error) {
 	config := model.Config{}
+	evaluation := model.Evaluation{}
 	userHomeDir, err := c.os.UserHomeDir()
 	if err != nil {
 		return config, fmt.Errorf("couldn't get user config dir: %q", err)
 	}
 	userConfigDir := c.path.Join(userHomeDir, ".config")
 	configFilePath := c.configFilePath(userConfigDir)
 	file, _ := c.os.ReadFile(configFilePath)
-	// TODO: add to debugging logs
+	// TODO: add to debugging logs (Update, added details string)
 	// if err != nil {
-	// 	return config, fmt.Errorf("couldn't read config file: %q", err)
+	// 	return config, "", fmt.Errorf("couldn't read config file: %q", err)
 	// }
-	err = toml.Unmarshal(file, &config)
-	if err != nil {
-		return config, fmt.Errorf("couldn't unmarshal config file: %q", err)
+	_ = toml.Unmarshal(file, &evaluation)
+	if evaluation.StrictMode {
+		reader := strings.NewReader(string(file))
+		d := toml.NewDecoder(reader)
+		d.DisallowUnknownFields() // enable the strict mode
+		err = d.Decode(&config)
+		if err != nil {
+			var details *toml.StrictMissingError
+			if errors.As(err, &details) {
+				return config, &ConfigError{Err: err.Error(), HumanDetails: details.String()}
+			}
+			return config, err
+		}
+	} else {
+		err = toml.Unmarshal(file, &config)
+		if err != nil {
+			var derr *toml.DecodeError
+			if errors.As(err, &derr) {
+				return config, &ConfigError{Err: err.Error(), HumanDetails: derr.String()}
+			}
+		}
 	}
 
 	for _, importPath := range config.ImportPaths {

main.go

@@ -88,12 +88,12 @@ func createLoggerFile(userTempDir string) (*os.File, error) {
 	now := time.Now()
 	date := fmt.Sprintf("%s.log", now.Format("2006-01-02"))
 
-	if err := os.MkdirAll(path.Join(userTempDir, ".seshtmp"), 0755); err != nil {
+	if err := os.MkdirAll(path.Join(userTempDir, ".seshtmp"), 0o755); err != nil {
 		return nil, err
 	}
 
 	fileFullPath := path.Join(userTempDir, ".seshtmp", date)
-	file, err := os.OpenFile(fileFullPath, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+	file, err := os.OpenFile(fileFullPath, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0o666)
 	if err != nil {
 		return nil, err
 	}

model/config.go

@@ -2,13 +2,17 @@ package model
 
 type (
 	Config struct {
+		StrictMode           bool                 `toml:"strict_mode"`
 		ImportPaths          []string             `toml:"import"`
 		DefaultSessionConfig DefaultSessionConfig `toml:"default_session"`
 		Blacklist            []string             `toml:"blacklist"`
 		SessionConfigs       []SessionConfig      `toml:"session"`
-    SortOrder            []string             `toml:"sort_order"`
+		SortOrder            []string             `toml:"sort_order"`
 		WindowConfigs        []WindowConfig       `toml:"window"`
 	}
+	Evaluation struct {
+		StrictMode bool `toml:"strict_mode"`
+	}
 
 	DefaultSessionConfig struct {
 		// TODO: mention breaking change in v2 release notes
@@ -28,8 +32,8 @@ type (
 	}
 
 	WindowConfig struct {
-		Name               string `toml:"name"`
-		StartupScript      string `toml:"startup_script"`
-		Path               string `toml:"path"`
+		Name          string `toml:"name"`
+		StartupScript string `toml:"startup_script"`
+		Path          string `toml:"path"`
 	}
 )

seshcli/seshcli.go

@@ -1,6 +1,8 @@
 package seshcli
 
 import (
+	"errors"
+	"fmt"
 	"log/slog"
 
 	"github.com/urfave/cli/v2"
@@ -53,6 +55,11 @@ func App(version string) cli.App {
 	config, err := configurator.NewConfigurator(os, path, runtime).GetConfig()
 	// TODO: make sure to ignore the error if the config doesn't exist
 	if err != nil {
+		var human *configurator.ConfigError
+		if errors.As(err, &human) {
+			// No panic here because it leads to panic in the end of the root branch anyway.
+			fmt.Printf("Couldn't parse config, err: %v\n details:\n %s\n", err.Error(), human.Human())
+		}
 		slog.Error("seshcli/seshcli.go: App", "error", err)
 		panic(err)
 	}