package main

import (
	"context"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"os"
	"os/signal"
	"path"
	"sync"

	"gitea.thegux.fr/hmdeploy/deployers"
	"gitea.thegux.fr/hmdeploy/docker"
	"gitea.thegux.fr/hmdeploy/models"
	"gitea.thegux.fr/hmdeploy/scheduler"
	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
)

const (
	HMDeployDirname string = ".homeserver"
	NetworkFilename string = "map.json"

	SchedulerNbWorkers     uint8  = 4
	SchedulerQueueCapacity uint32 = 30

	MaxDeployers int = 2
)

var HOME_PATH = os.Getenv("HOME")

var (
	ErrNetInfoNotFound   = errors.New("unable to get net info")
	ErrDeployerInit      = errors.New("unable to initialize deployer")
	ErrGenerateTasksTree = errors.New("unable to generate tasks tree")
)

type Option struct {
	fnCancel context.CancelFunc
}

type InitOption func(o *Option)

func WithGlobalCancellation(fnCancel context.CancelFunc) InitOption {
	return func(o *Option) {
		o.fnCancel = fnCancel
	}
}

func initLogger() {
	zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
	log.Logger = log.With().Caller().Logger().Output(zerolog.ConsoleWriter{Out: os.Stderr})
}

// loadHMMap loads your instance configuration map from `$HOME/.homeserver` dir.
func loadHMMap() (models.HMMap, error) {
	var hmmap models.HMMap

	hmmap_path := path.Join(HOME_PATH, HMDeployDirname, NetworkFilename)
	c, err := os.ReadFile(hmmap_path)
	if err != nil {
		return hmmap, fmt.Errorf(
			"unable to load configuration from src=%s, err=%v",
			hmmap_path,
			err,
		)
	}

	if err := json.Unmarshal(c, &hmmap); err != nil {
		return hmmap, fmt.Errorf(
			"unable to parse configuration from src=%s, err=%v",
			hmmap_path,
			err,
		)
	}

	log.Info().Str("conf", hmmap_path).Msg("hmmap load successfully")
	return hmmap, nil
}

// initDeployers instanciates from `Project` and `HMMap` needed deployers and returns them.
//
// You can provide as an optional arg:
//   - WithGlobalCancellation(fnCancel context.CancelFunc): close the global context, notifying all deployers to stop
func initDeployers(
	ctx context.Context,
	hmmap *models.HMMap,
	project *models.Project,
	options ...InitOption,
) ([]deployers.IDeployer, error) {
	swarmNet := hmmap.GetSwarmNetInfo()
	if swarmNet == nil {
		return nil, fmt.Errorf("%w, swarm net info does not exist", ErrNetInfoNotFound)
	}

	dcli := docker.NewClient()
	sd, err := deployers.NewSwarmDeployer(ctx, project, swarmNet, &dcli)
	if err != nil {
		return nil, fmt.Errorf("%w, unable to init swarm deployer, err=%v", ErrDeployerInit, err)
	}

	var nd deployers.NginxDeployer
	if project.Deps.NginxFile != "" {
		nginxNet := hmmap.GetNginxNetInfo()
		if nginxNet == nil {
			return nil, fmt.Errorf("%w, nginx net info does not exist", ErrNetInfoNotFound)
		}

		d, err := deployers.NewNginxDeployer(ctx, project, nginxNet)
		if err != nil {
			return nil, fmt.Errorf(
				"%w, unable to init nginx deployer, err=%v",
				ErrDeployerInit,
				err,
			)
		}

		nd = d
	}

	var opt Option
	for _, o := range options {
		o(&opt)
	}

	if opt.fnCancel != nil {
		sd.SetCancellationFunc(opt.fnCancel)
		nd.SetCancellationFunc(opt.fnCancel)
	}

	return []deployers.IDeployer{&sd, &nd}, nil
}

// generateTasksTree returns a list of linked `Task` to submit.
//
// It's here that all tasks are linked each other to provide the deployment ordering.
func generateTasksTree(deployers []deployers.IDeployer, destroy bool) ([]*scheduler.Task, error) {
	if len(deployers) != MaxDeployers {
		return nil, fmt.Errorf("%w, deployers len should be equals to 2", ErrGenerateTasksTree)
	}

	sd := deployers[0]
	nd := deployers[1]

	tasks := []*scheduler.Task{}

	if destroy {
		swarmDestroy := scheduler.NewTask("swarm-destroy", sd.Destroy)
		destroyTask := scheduler.NewTask("nginx-destroy", nd.Destroy, swarmDestroy)
		tasks = append(tasks, destroyTask)
		return tasks, nil
	}

	var swarmTask *scheduler.Task
	if nd != nil {
		deployNginx := scheduler.NewTask("nginx-deploy", nd.Deploy)
		swarmTask = scheduler.NewTask("swarm-deploy", sd.Deploy, deployNginx)
	} else {
		swarmTask = scheduler.NewTask("swarm-deploy", sd.Deploy)
	}

	swarmTask = scheduler.NewTask("swarm-build", sd.Build, swarmTask)
	tasks = append(tasks, swarmTask, scheduler.NewTask("nginx-build", nd.Build))

	return tasks, nil
}

// waitForCompletion waits for all deployers to complete.
//
// After the completion, deployers `Clear` methods are executed to clean all ressources.
// Then the scheduler is stopped to terminate the engine.
func waitForCompletion(
	deployers []deployers.IDeployer,
	s *scheduler.Scheduler,
	destroy bool,
) error {
	var wg sync.WaitGroup

	for idx := range deployers {
		if d := deployers[idx]; d != nil {
			wg.Add(1)
			go func() {
				defer wg.Done()
				<-d.Done()
			}()
		}
	}

	wg.Wait()

	var errs []error
	for idx := range deployers {
		if d := deployers[idx]; d != nil {
			errs = append(errs, d.Error())
			if !destroy {
				s.Submit(scheduler.NewTask(string(d.Type()), d.Clear)) //nolint: errcheck // TODO
			}
		}
	}

	s.Stop()
	<-s.Done()

	return errors.Join(errs...)
}

func main() {
	ctx, fnCancel := signal.NotifyContext(
		context.Background(),
		os.Interrupt,
		os.Kill,
	)

	initLogger()
	log.Info().Msg("hmdeploy started")

	projectDir := flag.String("path", ".", "define the .homeserver project root dir")
	destroy := flag.Bool("destroy", false, "delete the deployed project")
	flag.Parse()

	hmmap, err := loadHMMap()
	if err != nil {
		log.Fatal().Err(err).Msg("failed to load conf")
	}

	project, err := models.ProjectFromDir(*projectDir)
	if err != nil {
		log.Fatal().Str("dir", *projectDir).Err(err).Msg("unable to init project from directory")
	}
	log.Info().
		Str("dir", project.Dir).
		Str("name", project.Name).
		Msg("project initialized with success")

	deployers, err := initDeployers(ctx, &hmmap, &project, WithGlobalCancellation(fnCancel))
	if err != nil {
		log.Fatal().Err(err).Msg("unable to init deployers")
	}

	tasks, err := generateTasksTree(deployers, *destroy)
	if err != nil {
		log.Fatal().Err(err).Msg("unable to generate tasks tree")
	}

	s := scheduler.NewScheduler(
		context.Background(),
		SchedulerQueueCapacity,
		SchedulerNbWorkers,
		tasks...,
	)

	if err := waitForCompletion(deployers, s, *destroy); err != nil {
		log.Fatal().
			Err(err).
			Str("name", project.Name).
			Msg("unable to deploy project, see logs for details")
	}

	log.Info().Str("name", project.Name).Msg("project deployed successfully")
}