package admin

import (
	"context"
	"encoding/json"
	"errors"

	"github.com/google/uuid"
)

// Permission catalog frozen in ECR-013A Spec.
const (
	PermUsersRead            = "admin.users.read"
	PermMembershipGrant      = "admin.users.membership.grant"
	PermAskQuotaGrant        = "admin.users.ask_quota.grant"
	PermOrdersRead           = "admin.orders.read"
	PermAuditRead            = "admin.audit.read"
	PermAnalyticsRead        = "admin.analytics.read"
	PermContentWrite         = "admin.content.write"
	PermRolesRead            = "admin.roles.read"
	PermRolesWrite           = "admin.roles.write"
	PermUsersStatusWrite     = "admin.users.status.write"
	PermMembershipPlansRead  = "admin.membership.plans.read"
	PermMembershipPlansWrite = "admin.membership.plans.write"
	PermMembershipCodesRead  = "admin.membership.codes.read"
	PermMembershipCodesWrite = "admin.membership.codes.write"
	PermAskRead              = "admin.ask.read"
	PermAskFeedbackWrite     = "admin.ask.feedback.write"
	PermContentSafetyRead    = "admin.content_safety.read"
	PermAIConfigRead         = "admin.ai_config.read"
	PermCrisisRead           = "admin.crisis.read"
	PermCMSRead              = "admin.cms.read"
	PermPrivacyRead = "admin.privacy.read"
	PermExploreRead = "admin.explore.read"
	PermGrowthRead = "admin.growth.read"
)

var knownPermissions = map[string]struct{}{
	PermUsersRead: {}, PermMembershipGrant: {}, PermAskQuotaGrant: {},
	PermOrdersRead: {}, PermAuditRead: {}, PermAnalyticsRead: {},
	PermContentWrite: {}, PermRolesRead: {}, PermRolesWrite: {},
	PermUsersStatusWrite: {}, PermMembershipPlansRead: {}, PermMembershipPlansWrite: {},
	PermMembershipCodesRead: {}, PermMembershipCodesWrite: {},
	PermAskRead: {}, PermAskFeedbackWrite: {}, PermContentSafetyRead: {},
	PermAIConfigRead: {}, PermCrisisRead: {}, PermCMSRead: {}, PermGrowthRead: {}, PermExploreRead: {}, PermPrivacyRead: {},
}

var (
	ErrForbidden     = errString("forbidden")
	ErrRoleNotFound  = errString("role not found")
	ErrInvalidPerm   = errString("invalid permission code")
	ErrProtectSystem = errString("system role protected")
)

// AdminMe is the public admin profile (with RBAC).
type AdminMe struct {
	ID          uuid.UUID `json:"id"`
	Username    string    `json:"username"`
	Role        string    `json:"role,omitempty"`
	Permissions []string  `json:"permissions"`
}

// RoleDTO is list/detail payload.
type RoleDTO struct {
	ID          uuid.UUID `json:"id"`
	Name        string    `json:"name"`
	System      bool      `json:"system"`
	Permissions []string  `json:"permissions,omitempty"`
}

// HasPermission reports whether admin holds code.
func (s *Service) HasPermission(ctx context.Context, adminID uuid.UUID, code string) (bool, error) {
	perms, err := s.Repo.ListPermissionsForAdmin(ctx, adminID)
	if err != nil {
		return false, err
	}
	for _, p := range perms {
		if p == code {
			return true, nil
		}
	}
	return false, nil
}

// DenyPermission audits a forbidden attempt.
func (s *Service) DenyPermission(ctx context.Context, adminID uuid.UUID, code, path string) {
	meta, _ := json.Marshal(map[string]string{"permission": code, "path": path})
	_ = s.Repo.InsertAudit(ctx, adminID, "permission.denied", "permission", code, meta)
}

// Me returns the current admin profile with permissions.
func (s *Service) Me(ctx context.Context, adminID uuid.UUID) (*AdminMe, error) {
	acc, err := s.Repo.FindAccountByID(ctx, adminID)
	if err != nil || acc == nil {
		return nil, errors.New("admin not found")
	}
	perms, err := s.Repo.ListPermissionsForAdmin(ctx, adminID)
	if err != nil {
		return nil, err
	}
	if perms == nil {
		perms = []string{}
	}
	_, roleName, _ := s.Repo.GetAdminRoleMeta(ctx, adminID)
	return &AdminMe{ID: acc.ID, Username: acc.Username, Role: roleName, Permissions: perms}, nil
}

// ListRoles returns roles without permissions.
func (s *Service) ListRoles(ctx context.Context) ([]RoleDTO, error) {
	roles, err := s.Repo.ListAdminRoles(ctx)
	if err != nil {
		return nil, err
	}
	out := make([]RoleDTO, 0, len(roles))
	for _, r := range roles {
		out = append(out, RoleDTO{ID: r.ID, Name: r.Name, System: r.System})
	}
	return out, nil
}

// GetRole returns role + permissions.
func (s *Service) GetRole(ctx context.Context, id uuid.UUID) (*RoleDTO, error) {
	role, err := s.Repo.GetAdminRole(ctx, id)
	if err != nil || role == nil {
		return nil, ErrRoleNotFound
	}
	perms, err := s.Repo.ListRolePermissions(ctx, id)
	if err != nil {
		return nil, err
	}
	if perms == nil {
		perms = []string{}
	}
	return &RoleDTO{ID: role.ID, Name: role.Name, System: role.System, Permissions: perms}, nil
}

// ReplaceRolePermissions updates permissions with audit.
func (s *Service) ReplaceRolePermissions(ctx context.Context, adminID, roleID uuid.UUID, codes []string) error {
	role, err := s.Repo.GetAdminRole(ctx, roleID)
	if err != nil || role == nil {
		return ErrRoleNotFound
	}
	for _, c := range codes {
		if _, ok := knownPermissions[c]; !ok {
			return ErrInvalidPerm
		}
	}
	if err := s.Repo.ReplaceRolePermissions(ctx, roleID, codes); err != nil {
		return err
	}
	meta, _ := json.Marshal(map[string]any{"permissions": codes, "role": role.Name})
	return s.Repo.InsertAudit(ctx, adminID, "roles.permissions.update", "admin_role", roleID.String(), meta)
}