package cabana

import (
	"embed"
	"io/fs"

	"git.golem15.com/golem15/summercms/modules/backpack"
	"git.golem15.com/golem15/summercms/modules/pact"
	"git.golem15.com/golem15/summercms/modules/party"
)

// The admin's own screens for backend administrators and roles (Settings →
// System), registered by cabana itself through an internal pseudo-plugin.
const (
	// PermissionManageUsers opens the Administrators screen. No role is
	// granted it in code: until an administrator grants it, only superusers
	// reach the screen.
	PermissionManageUsers = "backend.manage_users"
	// PermissionManageRoles opens the Roles screen. No role is granted it in
	// code either.
	PermissionManageRoles = "backend.manage_roles"
	// AdministratorsControllerID is the admin controller ID of the
	// Administrators screen, the target other plugins name to add record
	// actions to it (pact.HasAdminActionExtensions).
	AdministratorsControllerID = "summercms.cabana.users"
	// RolesControllerID is the admin controller ID of the Roles screen.
	RolesControllerID = "summercms.cabana.roles"
)

// backendScreensPluginID is the pseudo-plugin's ID. It is also the
// migration history ID of the backend tables (lagoon), which is untouched:
// the pseudo-plugin declares no migrations.
const backendScreensPluginID = "summercms.cabana"

// backendScreensFS holds the screens' admin YAML and partials. all: keeps
// the partials, whose names start with an underscore.
//
//go:embed all:backendscreens
var backendScreensFS embed.FS

// backendScreens is the internal pseudo-plugin that registers the
// Administrators and Roles screens, their two permissions and their settings
// entries. Activate appends it to the plugins only when some plugin
// registers admin controllers, so an application without an admin still
// boots without one. app is the activating application and reg the compiled
// registry, set once compilation is done; the controllers read both per
// request.
type backendScreens struct {
	app *backpack.App
	reg *Registry
}

var (
	_ party.Plugin             = (*backendScreens)(nil)
	_ pact.AdminAssets         = (*backendScreens)(nil)
	_ pact.HasAdminControllers = (*backendScreens)(nil)
	_ pact.HasPermissions      = (*backendScreens)(nil)
	_ pact.HasSettings         = (*backendScreens)(nil)
)

func (*backendScreens) ID() string                   { return backendScreensPluginID }
func (*backendScreens) Requires() []string           { return nil }
func (*backendScreens) Register(*backpack.App) error { return nil }
func (*backendScreens) Boot(*backpack.App) error     { return nil }

// AdminFS serves the embedded tree rooted at backendscreens/, so its paths
// start at controllers/ and models/.
func (*backendScreens) AdminFS() fs.FS {
	sub, err := fs.Sub(backendScreensFS, "backendscreens")
	if err != nil {
		return nil
	}
	return sub
}

func (s *backendScreens) AdminControllers() []pact.AdminController {
	return []pact.AdminController{usersAdmin{screens: s}, rolesAdmin{screens: s}}
}

// Permissions declares the two screen permissions with no role grants
// (D-04): an upgrade gives no existing role access to the screens.
func (*backendScreens) Permissions() []pact.Permission {
	return []pact.Permission{
		{Code: PermissionManageUsers, Tab: "backend::lang.permissions.tab_system", Label: "backend::lang.permissions.manage_users"},
		{Code: PermissionManageRoles, Tab: "backend::lang.permissions.tab_system", Label: "backend::lang.permissions.manage_roles"},
	}
}

// Settings links the screens from Settings → System; there is no navigation
// entry.
func (*backendScreens) Settings() []pact.SettingsItem {
	return []pact.SettingsItem{
		{
			Code:        "administrators",
			Label:       "backend::lang.user.menu_label",
			Description: "backend::lang.user.menu_description",
			Category:    "backend::lang.settings.category_system",
			Icon:        "users",
			Order:       100,
			Permissions: []string{PermissionManageUsers},
			Controller:  AdministratorsControllerID,
		},
		{
			Code:        "roles",
			Label:       "backend::lang.user.role.menu_label",
			Description: "backend::lang.user.role.menu_description",
			Category:    "backend::lang.settings.category_system",
			Icon:        "shield-check",
			Order:       110,
			Permissions: []string{PermissionManageRoles},
			Controller:  RolesControllerID,
		},
	}
}

// application is the activating app, or nil.
func (s *backendScreens) application() *backpack.App {
	if s == nil {
		return nil
	}
	return s.app
}

// registry is the compiled registry, or nil before compilation finished.
func (s *backendScreens) registry() *Registry {
	if s == nil {
		return nil
	}
	return s.reg
}

// withBackendScreens returns a new plugin slice with the pseudo-plugin
// appended, and the pseudo-plugin. plugins itself is never modified.
func withBackendScreens(app *backpack.App, plugins []party.Plugin) ([]party.Plugin, *backendScreens) {
	screens := &backendScreens{app: app}
	out := make([]party.Plugin, 0, len(plugins)+1)
	out = append(out, plugins...)
	return append(out, screens), screens
}