/*
Package svc helps you write Windows Service executables without getting in the way of other target platforms.

To get started, implement the Init, Start, and Stop methods to do
any work needed during these steps.

Init and Start cannot block. Launch long-running code in a new Goroutine.

Stop may block for a short amount of time to attempt clean shutdown.

Call svc.Run() with a reference to your svc.Service implementation to start your program.

When running in console mode Ctrl+C is treated like a Stop Service signal.

For a full guide visit https://github.com/judwhite/go-svc
*/
package svc

import (
	"context"
	"errors"
	"os"
	"os/signal"
)

// Create variable signal.Notify function so we can mock it in tests
var signalNotify = signal.Notify

var ErrStop = errors.New("stopping service")

// Service interface contains Start and Stop methods which are called
// when the service is started and stopped. The Init method is called
// before the service is started, and after it's determined if the program
// is running as a Windows Service.
//
// The Start and Init methods must be non-blocking.
//
// Implement this interface and pass it to the Run function to start your program.
type Service interface {
	// Init is called before the program/service is started and after it's
	// determined if the program is running as a Windows Service. This method must
	// be non-blocking.
	Init(Environment) error

	// Start is called after Init. This method must be non-blocking.
	Start() error

	// Stop is called when Handle() returns ErrStop or when a
	// Windows Service is stopped.
	Stop() error
}

// Handler is an optional interface a Service can implement.
// When implemented, Handle() is called when a signal is received.
// Returning ErrStop from this method will result in Service.Stop() being called.
type Handler interface {
	Handle(os.Signal) error
}

// Context interface contains an optional Context function which a Service can implement.
// When implemented the context.Done() channel will be used in addition to signal handling
// to exit a process.
type Context interface {
	Context() context.Context
}

// Environment contains information about the environment
// your application is running in.
type Environment interface {
	// IsWindowsService reports whether the program is running as a Windows Service.
	IsWindowsService() bool
}