package exegroup

import (
	"context"
	"fmt"
	"time"
)

type Group struct {
	actors []*Actor
	cfg    config
}

func New(opts ...Option) *Group {
	cfg := config{}
	for _, opt := range opts {
		opt.apply(&cfg)
	}
	return &Group{
		cfg: cfg,
	}
}

func Default(opts ...Option) *Group {
	g := New(opts...)
	g.New().WithName("signal").WithGo(HandleSignal())
	return g
}

func (g *Group) New() *Actor {
	actor := NewActor().WithName(fmt.Sprintf("actor-%03d", len(g.actors)+1))
	g.actors = append(g.actors, actor)
	return actor
}

func (g *Group) Run(ctx context.Context) error {
	g.validate()
	ctx, cancel := context.WithCancel(ctx)
	c := make(chan error, len(g.actors))
	g.start(ctx, c)
	return g.wait(c, cancel)
}

func (g *Group) validate() {
	if len(g.actors) == 0 {
		panic("no actor")
	}
	for _, actor := range g.actors {
		if actor.goFunc == nil {
			panic(actor.name + "has nil goFunc")
		}
	}
}

func (g *Group) start(ctx context.Context, c chan error) {
	for _, actor := range g.actors {
		go func(actor *Actor) {
			var err error
			defer func() {
				if v := recover(); v != nil {
					err = fmt.Errorf("%v", v)
				}
				c <- err
			}()
			err = actor.goFunc(ctx)
		}(actor)
	}
}

func (g *Group) wait(c chan error, cancel context.CancelFunc) (err error) {
	err = <-c
	cancel()
	ctx := context.Background()
	if g.cfg.stopTimeout > 0 {
		ctx, cancel = context.WithTimeout(context.Background(), g.cfg.stopTimeout)
		defer cancel()
	}
	for _, m := range g.actors {
		if m.stopFunc != nil {
			if g.cfg.concurrentStop {
				go m.stopFunc(ctx)
			} else {
				m.stopFunc(ctx)
			}
		}
	}
	for i := 1; i < len(g.actors); i++ {
		select {
		case <-c:
		case <-ctx.Done():
			return
		}
	}
	return
}

type config struct {
	concurrentStop bool
	stopTimeout    time.Duration
}

type Option interface {
	apply(cfg *config)
}

type optionFunc func(cfg *config)

func (fn optionFunc) apply(cfg *config) {
	fn(cfg)
}

func WithConcurrentStop() Option {
	return optionFunc(func(cfg *config) {
		cfg.concurrentStop = true
	})
}

func WithStopTimeout(d time.Duration) Option {
	return optionFunc(func(cfg *config) {
		cfg.stopTimeout = d
	})
}