mcias/internal/policy/engine_test.go

package policy

import (
	"testing"
)

// adminInput is a convenience helper for building admin PolicyInputs.
func adminInput(action Action, resType ResourceType) PolicyInput {
	return PolicyInput{
		Subject:     "admin-uuid",
		AccountType: "human",
		Roles:       []string{"admin"},
		Action:      action,
		Resource:    Resource{Type: resType},
	}
}

func TestEvaluate_DefaultDeny(t *testing.T) {
	// No operator rules, non-admin subject: should hit default-deny for an
	// action that is not covered by built-in self-service defaults.
	input := PolicyInput{
		Subject:     "user-uuid",
		AccountType: "human",
		Roles:       []string{},
		Action:      ActionListAccounts,
		Resource:    Resource{Type: ResourceAccount},
	}
	effect, rule := Evaluate(input, nil)
	if effect != Deny {
		t.Errorf("expected Deny, got %s", effect)
	}
	if rule != nil {
		t.Errorf("expected nil rule on default-deny, got %+v", rule)
	}
}

func TestEvaluate_AdminWildcard(t *testing.T) {
	actions := []Action{
		ActionListAccounts, ActionCreateAccount, ActionReadPGCreds,
		ActionWritePGCreds, ActionReadAudit, ActionManageRules,
	}
	for _, a := range actions {
		t.Run(string(a), func(t *testing.T) {
			effect, rule := Evaluate(adminInput(a, ResourceAccount), nil)
			if effect != Allow {
				t.Errorf("admin should be allowed %s, got Deny", a)
			}
			if rule == nil || rule.ID != -1 {
				t.Errorf("expected admin wildcard rule (-1), got %v", rule)
			}
		})
	}
}

func TestEvaluate_SelfServiceLogout(t *testing.T) {
	input := PolicyInput{
		Subject:     "user-uuid",
		AccountType: "human",
		Roles:       []string{},
		Action:      ActionLogout,
		Resource:    Resource{Type: ResourceToken},
	}
	effect, _ := Evaluate(input, nil)
	if effect != Allow {
		t.Error("expected any authenticated user to be allowed to logout")
	}
}

func TestEvaluate_SelfServiceRenew(t *testing.T) {
	input := PolicyInput{
		Subject:     "user-uuid",
		AccountType: "human",
		Roles:       []string{},
		Action:      ActionRenewToken,
		Resource:    Resource{Type: ResourceToken},
	}
	effect, _ := Evaluate(input, nil)
	if effect != Allow {
		t.Error("expected any authenticated user to be allowed to renew token")
	}
}

func TestEvaluate_SystemOwnPGCreds(t *testing.T) {
	input := PolicyInput{
		Subject:     "svc-uuid",
		AccountType: "system",
		Roles:       []string{},
		Action:      ActionReadPGCreds,
		Resource: Resource{
			Type:      ResourcePGCreds,
			OwnerUUID: "svc-uuid", // owner matches subject
		},
	}
	effect, rule := Evaluate(input, nil)
	if effect != Allow {
		t.Errorf("system account should be allowed to read own pgcreds, got Deny")
	}
	if rule == nil || rule.ID != -4 {
		t.Errorf("expected built-in rule -4, got %v", rule)
	}
}

func TestEvaluate_SystemOtherPGCreds_Denied(t *testing.T) {
	// System account trying to read another system account's pgcreds.
	input := PolicyInput{
		Subject:     "svc-uuid",
		AccountType: "system",
		Roles:       []string{},
		Action:      ActionReadPGCreds,
		Resource: Resource{
			Type:      ResourcePGCreds,
			OwnerUUID: "other-svc-uuid", // different owner
		},
	}
	effect, _ := Evaluate(input, nil)
	if effect != Allow {
		// This is the expected behavior: default-deny.
		return
	}
	t.Error("system account must not read another account's pgcreds without an explicit rule")
}

func TestEvaluate_DenyWins(t *testing.T) {
	// Operator adds a Deny rule for a specific subject; a broader Allow rule
	// also matches. Deny must win regardless of order.
	operatorRules := []Rule{
		{
			ID:           1,
			Description:  "broad allow",
			Priority:     100,
			Actions:      []Action{ActionReadPGCreds},
			ResourceType: ResourcePGCreds,
			Effect:       Allow,
		},
		{
			ID:           2,
			Description:  "specific deny",
			Priority:     50, // higher precedence than the allow
			SubjectUUID:  "bad-actor-uuid",
			ResourceType: ResourcePGCreds,
			Effect:       Deny,
		},
	}
	input := PolicyInput{
		Subject:     "bad-actor-uuid",
		AccountType: "human",
		Roles:       []string{},
		Action:      ActionReadPGCreds,
		Resource:    Resource{Type: ResourcePGCreds},
	}
	effect, rule := Evaluate(input, operatorRules)
	if effect != Deny {
		t.Errorf("deny rule should win over allow rule, got Allow")
	}
	if rule == nil || rule.ID != 2 {
		t.Errorf("expected deny rule ID 2, got %v", rule)
	}
}

func TestEvaluate_ServiceNameGating(t *testing.T) {
	operatorRules := []Rule{
		{
			ID:           3,
			Description:  "alice may read payments-api pgcreds",
			Priority:     50,
			Roles:        []string{"svc:payments-api"},
			Actions:      []Action{ActionReadPGCreds},
			ResourceType: ResourcePGCreds,
			ServiceNames: []string{"payments-api"},
			Effect:       Allow,
		},
	}

	alice := PolicyInput{
		Subject:     "alice-uuid",
		AccountType: "human",
		Roles:       []string{"svc:payments-api"},
		Action:      ActionReadPGCreds,
		Resource: Resource{
			Type:        ResourcePGCreds,
			ServiceName: "payments-api",
		},
	}
	effect, _ := Evaluate(alice, operatorRules)
	if effect != Allow {
		t.Error("alice should be allowed to read payments-api pgcreds")
	}

	// Same principal, wrong service — should be denied.
	alice.Resource.ServiceName = "user-service"
	effect, _ = Evaluate(alice, operatorRules)
	if effect != Deny {
		t.Error("alice should be denied access to user-service pgcreds")
	}
}

func TestEvaluate_MachineTagGating(t *testing.T) {
	operatorRules := []Rule{
		{
			ID:           4,
			Description:  "deploy-agent: staging only",
			Priority:     50,
			SubjectUUID:  "deploy-agent-uuid",
			Actions:      []Action{ActionReadPGCreds},
			ResourceType: ResourcePGCreds,
			RequiredTags: []string{"env:staging"},
			Effect:       Allow,
		},
		{
			ID:           5,
			Description:  "deploy-agent: deny production (belt-and-suspenders)",
			Priority:     10, // evaluated before the allow
			SubjectUUID:  "deploy-agent-uuid",
			ResourceType: ResourcePGCreds,
			RequiredTags: []string{"env:production"},
			Effect:       Deny,
		},
	}

	staging := PolicyInput{
		Subject:     "deploy-agent-uuid",
		AccountType: "system",
		Roles:       []string{},
		Action:      ActionReadPGCreds,
		Resource: Resource{
			Type: ResourcePGCreds,
			Tags: []string{"env:staging", "svc:payments-api"},
		},
	}
	effect, _ := Evaluate(staging, operatorRules)
	if effect != Allow {
		t.Error("deploy-agent should be allowed to read staging pgcreds")
	}

	production := staging
	production.Resource.Tags = []string{"env:production", "svc:payments-api"}
	effect, rule := Evaluate(production, operatorRules)
	if effect != Deny {
		t.Error("deploy-agent should be denied access to production pgcreds")
	}
	if rule == nil || rule.ID != 5 {
		t.Errorf("expected deny rule ID 5 for production, got %v", rule)
	}
}

func TestEvaluate_OwnerMatchesSubject(t *testing.T) {
	// Operator rule: a user may read account details for accounts they own.
	operatorRules := []Rule{
		{
			ID:                  6,
			Description:         "principals may read their own account",
			Priority:            50,
			Actions:             []Action{ActionReadAccount},
			ResourceType:        ResourceAccount,
			OwnerMatchesSubject: true,
			Effect:              Allow,
		},
	}

	// Reading own account — should be allowed.
	own := PolicyInput{
		Subject:     "user-uuid",
		AccountType: "human",
		Roles:       []string{},
		Action:      ActionReadAccount,
		Resource: Resource{
			Type:      ResourceAccount,
			OwnerUUID: "user-uuid",
		},
	}
	effect, _ := Evaluate(own, operatorRules)
	if effect != Allow {
		t.Error("user should be allowed to read their own account")
	}

	// Reading another user's account — should be denied.
	other := own
	other.Resource.OwnerUUID = "other-uuid"
	effect, _ = Evaluate(other, operatorRules)
	if effect != Deny {
		t.Error("user must not read another user's account without an explicit rule")
	}
}

func TestEvaluate_PriorityOrder(t *testing.T) {
	// Two Allow rules at different priorities: the lower-priority number wins.
	operatorRules := []Rule{
		{ID: 10, Description: "low priority allow", Priority: 200, Actions: []Action{ActionReadAudit}, Effect: Allow},
		{ID: 11, Description: "high priority allow", Priority: 10, Actions: []Action{ActionReadAudit}, Effect: Allow},
	}
	input := PolicyInput{
		Subject:     "user-uuid",
		AccountType: "human",
		Roles:       []string{},
		Action:      ActionReadAudit,
		Resource:    Resource{Type: ResourceAuditLog},
	}
	_, rule := Evaluate(input, operatorRules)
	if rule == nil || rule.ID != 11 {
		t.Errorf("expected higher-priority rule (ID 11) to match first, got %v", rule)
	}
}

func TestEvaluate_MultipleRequiredTags(t *testing.T) {
	// RequiredTags requires ALL tags to be present.
	operatorRules := []Rule{
		{
			ID:           20,
			Description:  "allow if both env:staging and svc:payments-api tags present",
			Priority:     50,
			Actions:      []Action{ActionReadPGCreds},
			ResourceType: ResourcePGCreds,
			RequiredTags: []string{"env:staging", "svc:payments-api"},
			Effect:       Allow,
		},
	}

	// Both tags present — allowed.
	input := PolicyInput{
		Subject:     "user-uuid",
		AccountType: "human",
		Roles:       []string{},
		Action:      ActionReadPGCreds,
		Resource: Resource{
			Type: ResourcePGCreds,
			Tags: []string{"env:staging", "svc:payments-api", "extra:tag"},
		},
	}
	effect, _ := Evaluate(input, operatorRules)
	if effect != Allow {
		t.Error("both required tags present: should be allowed")
	}

	// Only one tag present — denied (default-deny).
	input.Resource.Tags = []string{"env:staging"}
	effect, _ = Evaluate(input, operatorRules)
	if effect != Deny {
		t.Error("only one required tag present: should be denied")
	}

	// No tags — denied.
	input.Resource.Tags = nil
	effect, _ = Evaluate(input, operatorRules)
	if effect != Deny {
		t.Error("no tags: should be denied")
	}
}

func TestEvaluate_AccountTypeGating(t *testing.T) {
	// Rule only applies to system accounts.
	operatorRules := []Rule{
		{
			ID:           30,
			Description:  "system accounts may list accounts",
			Priority:     50,
			AccountTypes: []string{"system"},
			Actions:      []Action{ActionListAccounts},
			Effect:       Allow,
		},
	}

	sysInput := PolicyInput{
		Subject:     "svc-uuid",
		AccountType: "system",
		Roles:       []string{},
		Action:      ActionListAccounts,
		Resource:    Resource{Type: ResourceAccount},
	}
	effect, _ := Evaluate(sysInput, operatorRules)
	if effect != Allow {
		t.Error("system account should be allowed by account-type rule")
	}

	humanInput := sysInput
	humanInput.AccountType = "human"
	effect, _ = Evaluate(humanInput, operatorRules)
	if effect != Deny {
		t.Error("human account should not match system-only rule")
	}
}