package rules

// EmailContext contains the data available to rules for evaluation.
type EmailContext struct {
	Sender    string
	Subject   string
	MessageID string
}

// RuleResult is the output of evaluating a single rule.
type RuleResult struct {
	Accepted bool
	Reason   string
	Metadata map[string]string
}

// Accept returns a passing RuleResult.
func Accept() RuleResult {
	return RuleResult{Accepted: true}
}

// Reject returns a failing RuleResult with a reason.
func Reject(reason string) RuleResult {
	return RuleResult{Accepted: false, Reason: reason}
}

// WithMetadata attaches a key-value pair to the result.
func (r RuleResult) WithMetadata(key, value string) RuleResult {
	if r.Metadata == nil {
		r.Metadata = map[string]string{key: value}
	} else {
		r.Metadata[key] = value
	}
	return r
}

// Rule evaluates an email against operator-configurable policy.
type Rule interface {
	Name() string
	Evaluate(ctx EmailContext) RuleResult
}