package authz

import (
	"agent-system-backend/internal/authz/catalog"
	"agent-system-backend/internal/store"
)

type Descriptor = catalog.Descriptor
type Scope = catalog.Scope

const (
	ScopeSystem  = catalog.ScopeSystem
	ScopeProject = catalog.ScopeProject
)

func Catalog() []Descriptor { return catalog.Catalog() }

type Decision struct {
	Allowed        bool   `json:"allowed"`
	ActionID       string `json:"actionId"`
	Source         string `json:"source,omitempty"`
	Reason         string `json:"reason,omitempty"`
	AuthorityEpoch int64  `json:"authorityEpoch"`
}

type Service struct {
	store *store.Store
}

func NewService(st *store.Store) *Service { return &Service{store: st} }

func (s *Service) AuthorizeSystem(actor, actionID string) Decision {
	decision := Decision{ActionID: actionID}
	descriptor, ok := catalog.DescriptorByID(actionID)
	if !ok || descriptor.Scope != catalog.ScopeSystem || s == nil || s.store == nil {
		decision.Reason = "unknown-system-action"
		return decision
	}
	epoch, err := s.store.AuthorityEpoch()
	if err != nil {
		decision.Reason = "authority-unavailable"
		return decision
	}
	decision.AuthorityEpoch = epoch
	account, err := s.store.GetAccountByOwner(actor)
	if err != nil || !account.Enabled {
		decision.Reason = "account-unavailable"
		return decision
	}
	// Project access comes only from the actor's role (R2): neither is_admin
	// nor a system grant confers it.
	if actionID == catalog.ProjectAccessAction {
		roleAllowed, _, err := s.store.RolePermissionAllowed(actor, actionID)
		if err != nil {
			decision.Reason = "authority-unavailable"
			return decision
		}
		if roleAllowed {
			decision.Allowed, decision.Source = true, "role"
			return decision
		}
		decision.Reason = "not-granted"
		return decision
	}
	// is_admin remains the narrow bootstrap/root recovery source. Ordinary
	// delegated management uses explicit system_grants.
	if account.IsAdmin {
		decision.Allowed, decision.Source = true, "bootstrap-admin"
		return decision
	}
	allowed, err := s.store.SystemGrantAllowed(actor, actionID)
	if err != nil {
		decision.Reason = "authority-unavailable"
		return decision
	}
	if allowed {
		decision.Allowed, decision.Source = true, "system-grant"
		return decision
	}
	decision.Reason = "not-granted"
	return decision
}

func (s *Service) EffectiveSystemActions(actor string) []string {
	actions := []string{}
	for _, descriptor := range catalog.Catalog() {
		if descriptor.Scope != catalog.ScopeSystem {
			continue
		}
		if decision := s.AuthorizeSystem(actor, descriptor.ActionID); decision.Allowed {
			actions = append(actions, descriptor.ActionID)
		}
	}
	return actions
}