package console

import (
	"context"
	"errors"
	"fmt"
	"io"
	"os"
	"os/signal"
	"time"
)

type C[A any] struct {
	io.Reader
	io.Writer
	err       io.Writer
	args      A
	abort     func()
	cancelfns []func(context.Context) error
}

func New[A any](args A) (context.Context, *C[A]) {
	ctx := context.Background()
	ctx, abort := context.WithCancel(ctx)
	ctx, stop := signal.NotifyContext(ctx, os.Interrupt)
	go func() { <-ctx.Done(); stop() }() // restore interrupt function

	console := &C[A]{Reader: os.Stdin, Writer: os.Stdout, err: os.Stderr, args: args, abort: abort}
	return ctx, console
}

func (c *C[A]) Args() A {
	return c.args
}
func (c *C[A]) Shutdown() error {
	fmt.Fprintln(c.err, "shutting down ", len(c.cancelfns), " cancel functions...")
	defer fmt.Fprintln(c.err, "done")

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	c.abort()
	var err error
	for _, fn := range c.cancelfns {
		err = errors.Join(err, fn(ctx))
	}
	return err
}
func (c *C[A]) AddCancel(fn func(context.Context) error) { c.cancelfns = append(c.cancelfns, fn) }

func (c *C[A]) IfFatal(err error) {
	if err == nil {
		return
	}
	fmt.Fprintln(c.err, err)
	err = c.Shutdown()
	if err != nil {
		fmt.Fprintln(c.err, err)
	}
	os.Exit(1)
}