refactor: move CEL checker to its own package

Signed-off-by: Xe Iaso <me@xeiaso.net>

lib/checker/expression/config.go

@@ -0,0 +1,130 @@
+package expression
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"slices"
+	"strings"
+)
+
+var (
+	ErrExpressionOrListMustBeStringOrObject = errors.New("expression: this must be a string or an object")
+	ErrExpressionEmpty                      = errors.New("expression: this expression is empty")
+	ErrExpressionCantHaveBoth               = errors.New("expression: expression block can't contain multiple expression types")
+)
+
+type Config struct {
+	Expression string   `json:"-" yaml:"-"`
+	All        []string `json:"all,omitempty" yaml:"all,omitempty"`
+	Any        []string `json:"any,omitempty" yaml:"any,omitempty"`
+}
+
+func (eol Config) String() string {
+	switch {
+	case len(eol.Expression) != 0:
+		return eol.Expression
+	case len(eol.All) != 0:
+		var sb strings.Builder
+		for i, pred := range eol.All {
+			if i != 0 {
+				fmt.Fprintf(&sb, " && ")
+			}
+			fmt.Fprintf(&sb, "( %s )", pred)
+		}
+		return sb.String()
+	case len(eol.Any) != 0:
+		var sb strings.Builder
+		for i, pred := range eol.Any {
+			if i != 0 {
+				fmt.Fprintf(&sb, " || ")
+			}
+			fmt.Fprintf(&sb, "( %s )", pred)
+		}
+		return sb.String()
+	}
+	panic("this should not happen")
+}
+
+func (eol Config) Equal(rhs *Config) bool {
+	if eol.Expression != rhs.Expression {
+		return false
+	}
+
+	if !slices.Equal(eol.All, rhs.All) {
+		return false
+	}
+
+	if !slices.Equal(eol.Any, rhs.Any) {
+		return false
+	}
+
+	return true
+}
+
+func (eol *Config) MarshalYAML() (any, error) {
+	switch {
+	case len(eol.All) == 1 && len(eol.Any) == 0:
+		eol.Expression = eol.All[0]
+		eol.All = nil
+	case len(eol.Any) == 1 && len(eol.All) == 0:
+		eol.Expression = eol.Any[0]
+		eol.Any = nil
+	}
+
+	if eol.Expression != "" {
+		return eol.Expression, nil
+	}
+
+	type RawExpressionOrList Config
+	return RawExpressionOrList(*eol), nil
+}
+
+func (eol *Config) MarshalJSON() ([]byte, error) {
+	switch {
+	case len(eol.All) == 1 && len(eol.Any) == 0:
+		eol.Expression = eol.All[0]
+		eol.All = nil
+	case len(eol.Any) == 1 && len(eol.All) == 0:
+		eol.Expression = eol.Any[0]
+		eol.Any = nil
+	}
+
+	if eol.Expression != "" {
+		return json.Marshal(string(eol.Expression))
+	}
+
+	type RawExpressionOrList Config
+	val := RawExpressionOrList(*eol)
+	return json.Marshal(val)
+}
+
+func (eol *Config) UnmarshalJSON(data []byte) error {
+	switch string(data[0]) {
+	case `"`: // string
+		return json.Unmarshal(data, &eol.Expression)
+	case "{": // object
+		type RawExpressionOrList Config
+		var val RawExpressionOrList
+		if err := json.Unmarshal(data, &val); err != nil {
+			return err
+		}
+		eol.All = val.All
+		eol.Any = val.Any
+
+		return nil
+	}
+
+	return ErrExpressionOrListMustBeStringOrObject
+}
+
+func (eol *Config) Valid() error {
+	if eol.Expression == "" && len(eol.All) == 0 && len(eol.Any) == 0 {
+		return ErrExpressionEmpty
+	}
+	if len(eol.All) != 0 && len(eol.Any) != 0 {
+		return ErrExpressionCantHaveBoth
+	}
+
+	return nil
+}