refactor: expose decision engine in public pkg

pkg/config/validation.go

@@ -0,0 +1,160 @@
+package config
+
+import (
+	"fmt"
+	"strings"
+
+	"k8s.io/apimachinery/pkg/labels"
+
+	"github.com/stakater/Reloader/internal/pkg/workload"
+)
+
+// ValidationError represents a configuration validation error.
+type ValidationError struct {
+	Field   string
+	Message string
+}
+
+func (e ValidationError) Error() string {
+	return fmt.Sprintf("config.%s: %s", e.Field, e.Message)
+}
+
+// ValidationErrors is a collection of validation errors.
+type ValidationErrors []ValidationError
+
+func (e ValidationErrors) Error() string {
+	if len(e) == 0 {
+		return ""
+	}
+	if len(e) == 1 {
+		return e[0].Error()
+	}
+	var b strings.Builder
+	b.WriteString("multiple configuration errors:\n")
+	for _, err := range e {
+		b.WriteString("  - ")
+		b.WriteString(err.Error())
+		b.WriteString("\n")
+	}
+	return b.String()
+}
+
+// Validate checks the configuration for errors and normalizes values.
+func (c *Config) Validate() error {
+	var errs ValidationErrors
+
+	switch c.ReloadStrategy {
+	case ReloadStrategyEnvVars, ReloadStrategyAnnotations:
+		// valid
+	case "":
+		c.ReloadStrategy = ReloadStrategyEnvVars
+	default:
+		errs = append(
+			errs, ValidationError{
+				Field:   "ReloadStrategy",
+				Message: fmt.Sprintf("invalid value %q, must be %q or %q", c.ReloadStrategy, ReloadStrategyEnvVars, ReloadStrategyAnnotations),
+			},
+		)
+	}
+
+	switch c.ArgoRolloutStrategy {
+	case ArgoRolloutStrategyRestart, ArgoRolloutStrategyRollout:
+		// valid
+	case "":
+		c.ArgoRolloutStrategy = ArgoRolloutStrategyRollout
+	default:
+		errs = append(
+			errs, ValidationError{
+				Field: "ArgoRolloutStrategy",
+				Message: fmt.Sprintf(
+					"invalid value %q, must be %q or %q", c.ArgoRolloutStrategy, ArgoRolloutStrategyRestart, ArgoRolloutStrategyRollout,
+				),
+			},
+		)
+	}
+
+	switch strings.ToLower(c.LogLevel) {
+	case "trace", "debug", "info", "warn", "warning", "error", "fatal", "panic", "":
+		// valid
+	default:
+		errs = append(
+			errs, ValidationError{
+				Field:   "LogLevel",
+				Message: fmt.Sprintf("invalid log level %q", c.LogLevel),
+			},
+		)
+	}
+
+	switch strings.ToLower(c.LogFormat) {
+	case "json", "":
+		// valid
+	default:
+		errs = append(
+			errs, ValidationError{
+				Field:   "LogFormat",
+				Message: fmt.Sprintf("invalid log format %q, must be \"json\" or empty", c.LogFormat),
+			},
+		)
+	}
+
+	c.IgnoredResources = normalizeToLower(c.IgnoredResources)
+
+	// Normalize ignored workloads to canonical Kind values (e.g., "cronjobs" -> "CronJob")
+	c.IgnoredWorkloads = normalizeToLower(c.IgnoredWorkloads)
+	normalizedWorkloads := make([]string, 0, len(c.IgnoredWorkloads))
+	for _, w := range c.IgnoredWorkloads {
+		kind, err := workload.KindFromString(w)
+		if err != nil {
+			errs = append(
+				errs, ValidationError{
+					Field:   "IgnoredWorkloads",
+					Message: fmt.Sprintf("unknown workload type %q", w),
+				},
+			)
+		} else {
+			normalizedWorkloads = append(normalizedWorkloads, string(kind))
+		}
+	}
+	c.IgnoredWorkloads = normalizedWorkloads
+
+	if len(errs) > 0 {
+		return errs
+	}
+	return nil
+}
+
+// normalizeToLower converts all strings in the slice to lowercase and removes empty strings.
+func normalizeToLower(items []string) []string {
+	if len(items) == 0 {
+		return items
+	}
+	result := make([]string, 0, len(items))
+	for _, item := range items {
+		item = strings.TrimSpace(strings.ToLower(item))
+		if item != "" {
+			result = append(result, item)
+		}
+	}
+	return result
+}
+
+// ParseSelectors parses a slice of selector strings into label selectors.
+func ParseSelectors(selectorStrings []string) ([]labels.Selector, error) {
+	if len(selectorStrings) == 0 {
+		return nil, nil
+	}
+
+	selectors := make([]labels.Selector, 0, len(selectorStrings))
+	for _, s := range selectorStrings {
+		s = strings.TrimSpace(s)
+		if s == "" {
+			continue
+		}
+		selector, err := labels.Parse(s)
+		if err != nil {
+			return nil, fmt.Errorf("invalid selector %q: %w", s, err)
+		}
+		selectors = append(selectors, selector)
+	}
+	return selectors, nil
+}