package main

import (
	"context"
	"flag"
	"fmt"
	"log"
	"net/http"
	"net/url"
	"os"
	"os/signal"
	"strings"
	"syscall"
	"time"

	"github.com/gen2brain/beeep"
	"github.com/schollz/progressbar/v3"
)

func main() {
	ctx, can := signal.NotifyContext(context.Background(), syscall.SIGINT)
	defer can()

	fs := flag.NewFlagSet(os.Args[0], flag.ContinueOnError)
	gcal := fs.Bool("gcal", false, "wait for google cal events")
	ntfy := fs.String("http", "", "https://squeaky2x3:dYbtypGkHXFtq1E00k2H42SPGUowi@ntfy.home.blapointe.com/alerts-render")
	if err := fs.Parse(os.Args[1:]); err != nil {
		panic(err)
	}

	if *gcal {
		if err := alertGCal(ctx, *ntfy); err != nil {
			panic(err)
		}
	} else {
		if err := alertAfter(ctx, *ntfy, fs.Args()[0]); err != nil {
			panic(err)
		}
	}
}

func alertGCal(ctx context.Context, ntfy string) error {
	gcal := NewGCal()
	if err := gcal.Login(ctx); err != nil {
		return err
	}

	events, err := gcal.EventsToday(ctx)
	if err != nil {
		return err
	}

	for _, event := range events {
		until := event.Time.Add(-1 * time.Minute)
		if until.Sub(time.Now()) < 1 {
			continue
		}

		log.Println("alerting about", event.Name, "at", until.Format("15:04"), "(", time.Until(until), ")")
		if err := alertAt(ctx, ntfy, until, event.Name, until.Format("15:04")); err != nil {
			return err
		}
	}

	return nil
}

func alertAfter(ctx context.Context, ntfy string, duration string) error {
	d, err := time.ParseDuration(duration)
	if err != nil {
		return err
	}
	return alertAt(ctx, ntfy, time.Now().Add(d), os.Args[0], "alerting after "+d.String())
}

func alertAt(ctx context.Context, ntfy string, deadline time.Time, title, msg string) error {
	n := int64(time.Until(deadline) / time.Second)
	bar := progressbar.Default(n)
	c := time.NewTicker(time.Second)
	defer c.Stop()
	func() {
		ctx, can := context.WithDeadline(ctx, deadline)
		defer can()
		for {
			select {
			case <-c.C:
			case <-ctx.Done():
				return
			}
			bar.Add(1)
		}
	}()
	bar.Finish()
	bar.Exit()

	if err := ctx.Err(); err == nil {
		beeep.Alert(title, msg, "/dev/null")
		if ntfy != "" {
			u, _ := url.Parse(ntfy)
			req, _ := http.NewRequest(http.MethodPost, u.String(), strings.NewReader(fmt.Sprintf("%s: %s", title, msg)))
			req = req.WithContext(ctx)
			http.DefaultClient.Do(req)
		}
	}

	return ctx.Err()
}