package daemon

import (
	"context"
	"fmt"
	"isle/bootstrap"

	"code.betamike.com/micropelago/pmux/pmuxlib"
	"dev.mediocregopher.com/mediocre-go-lib.git/mlog"
)

// Children manages all child processes of a network. Child processes are
// comprised of:
// - nebula
// - dnsmasq
// - garage (0 or more, depending on configured storage allocations)
type Children struct {
	logger *mlog.Logger
	opts   Opts

	pmuxCancelFn  context.CancelFunc
	pmuxStoppedCh chan struct{}
}

// NewChildren initialized and returns a Children instance. If initialization
// fails an error is returned.
func NewChildren(
	ctx context.Context,
	logger *mlog.Logger,
	daemonConfig Config,
	hostBootstrap bootstrap.Bootstrap,
	binDirPath string,
	opts *Opts,
) (
	*Children, error,
) {
	opts = opts.withDefaults()

	pmuxCtx, pmuxCancelFn := context.WithCancel(context.Background())

	c := &Children{
		logger:        logger,
		opts:          *opts,
		pmuxCancelFn:  pmuxCancelFn,
		pmuxStoppedCh: make(chan struct{}),
	}

	pmuxConfig, err := c.newPmuxConfig(binDirPath, daemonConfig, hostBootstrap)
	if err != nil {
		return nil, fmt.Errorf("generating pmux config: %w", err)
	}

	go func() {
		defer close(c.pmuxStoppedCh)
		pmuxlib.Run(pmuxCtx, c.opts.Stdout, c.opts.Stderr, pmuxConfig)
		c.logger.Debug(pmuxCtx, "pmux stopped")
	}()

	initErr := c.postPmuxInit(ctx, daemonConfig, hostBootstrap)
	if initErr != nil {
		logger.Warn(ctx, "failed to initialize Children, shutting down child processes", err)
		if err := c.Shutdown(); err != nil {
			panic(fmt.Sprintf(
				"failed to shut down child processes after initialization"+
					" error, there may be zombie children leftover."+
					" Original error: %v",
				initErr,
			))
		}

		return nil, initErr
	}

	return c, nil
}

// Shutdown blocks until all child processes have gracefully shut themselves
// down.
//
// If this returns an error then it's possible that child processes are
// still running and are no longer managed.
func (c *Children) Shutdown() error {
	c.pmuxCancelFn()
	<-c.pmuxStoppedCh
	return nil
}