package nasin

import "log"
import "image"
import "strings"
import "net/url"
import "git.tebibyte.media/tomo/tomo"
import "git.tebibyte.media/tomo/tomo/canvas"
import "git.tebibyte.media/tomo/nasin/internal/registrar"

// Application represents an application object.
type Application interface {
	// Describe returns a description of the application.
	Describe () ApplicationDescription

	// Init performs the initial setup of the application.
	Init () error
}

// ApplicationURLOpener is an application that can open a URL.
type ApplicationURLOpener interface {
	Application

	// OpenURL opens a new window with the contents of the given URL. If the
	// given URL is unsupported, it returns an error (for example, an image
	// viewer is not expected to open a text file). If the URL scheme is
	// empty, file:// is assumed.
	//
	// Applications should support the file:// scheme at the very least, and
	// should also support others like http:// and https:// if possible.
	OpenURL (*url.URL) error
}

// ApplicationDescription describes the name and type of an application.
type ApplicationDescription struct {
	// The name of the application.
	Name string

	// The ID of the application. This should be a well-known name, that is,
	// a reversed domain name owned by the author with the application name
	// as the subdomain.
	//
	// For example:
	//   com.example.Application
	ID string

	// Role describes what the application does.
	Role ApplicationRole
}

// String satisfies the fmt.Stringer interface.
func (application ApplicationDescription) String () string {
	if application.Name == "" {
		return string(application.Role)
	} else {
		return application.Name
	}
}

// ApplicationRole describes what an application does.
type ApplicationRole string; const (
	RoleUnknown           ApplicationRole = ""

	RoleWebBrowser        ApplicationRole = "Web Browser"
	RoleMesssanger        ApplicationRole = "Messsanger"
	RolePhone             ApplicationRole = "Phone"
	RoleMail              ApplicationRole = "Mail"

	RoleTerminalEmulator  ApplicationRole = "Terminal Emulator"
	RoleFileBrowser       ApplicationRole = "File Browser"
	RoleTextEditor        ApplicationRole = "Text Editor"

	RoleDocumentViewer    ApplicationRole = "Document Viewer"
	RoleWordProcessor     ApplicationRole = "Word Processor"
	RoleSpreadsheet       ApplicationRole = "Spreadsheet"
	RoleSlideshow         ApplicationRole = "Slideshow"
	RoleCalculator        ApplicationRole = "Calculator"

	RolePreferences       ApplicationRole = "Preferences"
	RoleProcessManager    ApplicationRole = "Process Manager"
	RoleSystemInformation ApplicationRole = "System Information"
	RoleManual            ApplicationRole = "Manual"

	RoleCamera            ApplicationRole = "Camera"
	RoleImageViewer       ApplicationRole = "Image Viewer"
	RoleMediaPlayer       ApplicationRole = "Media Player"
	RoleImageEditor       ApplicationRole = "Image Editor"
	RoleAudioEditor       ApplicationRole = "Audio Editor"
	RoleVideoEditor       ApplicationRole = "Video Editor"

	RoleClock             ApplicationRole = "Clock"
	RoleCalendar          ApplicationRole = "Calendar"
	RoleChecklist         ApplicationRole = "Checklist"
)

// Icon returns the icon ID for this role.
func (role ApplicationRole) Icon () tomo.Icon {
	if role == "" {
		return tomo.IconApplication
	} else {
		return tomo.Icon("Application" + strings.ReplaceAll(string(role), " ", ""))
	}
}

// RunApplication is like tomo.Run, but runs an application. If something fails
// to initialize, an error is written to the standard logger.
func RunApplication (application Application) {
	err := registrar.RegisterBackend()
	if err != nil { log.Fatal("nasin: could not register backend:", err) }
	err = tomo.Run(func () {
		err := registrar.SetTheme()
		if err != nil { log.Fatal("nasin: could not set theme:", err) }
		err = application.Init()
		if err != nil { log.Fatal("nasin: could not run application:", err) }
	})
	if err != nil { log.Fatal("nasin: could not run application:", err) }
}

// NewApplicationWindow creates a window for an application. It will
// automatically set window information to signal to the OS that the window is
// owned by the application. The window's icon will be automatically set by
// looking for an icon with the name of the application's ID. If that is not
// found, the default icon for the application's ApplicationRole will used.
func NewApplicationWindow (application Application, bounds image.Rectangle) (tomo.Window, error) {
	window, err := tomo.NewWindow(bounds)
	if err != nil { return nil, err }
	description := application.Describe()
	window.SetTitle(description.Name)
	setApplicationWindowIcon(window, description)
	return window, nil
}

func setApplicationWindowIcon (window tomo.Window, description ApplicationDescription) {
	allSizes := func (icon tomo.Icon) (sizes []canvas.Texture) {
		small  := icon.Texture(tomo.IconSizeSmall)
		medium := icon.Texture(tomo.IconSizeMedium)
		large  := icon.Texture(tomo.IconSizeLarge)
		if small  != nil { sizes = append(sizes,  small) }
		if medium != nil { sizes = append(sizes, medium) }
		if large  != nil { sizes = append(sizes,  large) }
		return sizes
	}

	if sizes := allSizes(tomo.Icon(description.ID)); len(sizes) > 0 {
		window.SetIcon(sizes...)
		return
	}
	if sizes := allSizes(description.Role.Icon()); len(sizes) > 0 {
		window.SetIcon(sizes...)
		return
	}
}