package spacesyncer

import (
	"context"
	"fmt"
	"sync"

	"gitlink.org.cn/cloudream/common/pkgs/async"
	"gitlink.org.cn/cloudream/common/pkgs/logger"
	"gitlink.org.cn/cloudream/jcs-pub/client/internal/db"
	"gitlink.org.cn/cloudream/jcs-pub/client/internal/metacache"
	clitypes "gitlink.org.cn/cloudream/jcs-pub/client/types"
	stgpool "gitlink.org.cn/cloudream/jcs-pub/common/pkgs/storage/pool"
)

const (
	logMod = "SpaceSyncer"
)

type SpaceSyncerEvent interface {
	IsSpaceSyncerEvent() bool
}

type SpaceSyncer struct {
	db        *db.DB
	stgPool   *stgpool.Pool
	spaceMeta *metacache.UserSpaceMeta
	lock      sync.Mutex
	tasks     map[clitypes.SpaceSyncTaskID]*task
}

func New(db *db.DB, stgPool *stgpool.Pool, spaceMeta *metacache.UserSpaceMeta) *SpaceSyncer {
	return &SpaceSyncer{
		db:        db,
		stgPool:   stgPool,
		spaceMeta: spaceMeta,
		tasks:     make(map[clitypes.SpaceSyncTaskID]*task),
	}
}

func (s *SpaceSyncer) Start() *async.UnboundChannel[SpaceSyncerEvent] {
	s.lock.Lock()
	defer s.lock.Unlock()

	log := logger.WithField("Mod", logMod)

	ch := async.NewUnboundChannel[SpaceSyncerEvent]()

	allTask, err := db.DoTx01(s.db, s.db.SpaceSyncTask().GetAll)
	if err != nil {
		log.Warnf("load task from db: %v", err)
	} else {
		var rms []clitypes.SpaceSyncTaskID
		for _, t := range allTask {
			ctx, cancel := context.WithCancel(context.Background())
			tsk := task{
				Task:     t,
				Context:  ctx,
				CancelFn: cancel,
			}

			switch tr := t.Trigger.(type) {
			case *clitypes.SpaceSyncTriggerOnce:
				// Once类型的任务没有执行完也不执行了
				rms = append(rms, t.TaskID)

			case *clitypes.SpaceSyncTriggerInterval:
				triggerInterval(s, &tsk, tr)

			case *clitypes.SpaceSyncTriggerAt:
				triggerAt(s, &tsk, tr)
			}

			log.Infof("load task %v from db", t.TaskID)
		}

		if len(rms) > 0 {
			err := s.db.SpaceSyncTask().BatchDelete(s.db.DefCtx(), rms)
			if err != nil {
				log.Warnf("batch delete task: %v", err)
			} else {
				log.Infof("%v once task deleted", len(rms))
			}
		}
	}

	return ch
}

func (s *SpaceSyncer) Stop() {
	s.lock.Lock()
	defer s.lock.Unlock()

	for _, t := range s.tasks {
		t.CancelFn()
	}

	s.tasks = make(map[clitypes.SpaceSyncTaskID]*task)
}

func (s *SpaceSyncer) CreateTask(t clitypes.SpaceSyncTask) (*TaskInfo, error) {
	log := logger.WithField("Mod", logMod)

	d := s.db
	err := d.DoTx(func(tx db.SQLContext) error {
		err := d.SpaceSyncTask().Create(tx, &t)
		if err != nil {
			return err
		}

		return nil
	})
	if err != nil {
		return nil, fmt.Errorf("creating space sync task: %w", err)
	}

	ctx, cancel := context.WithCancel(context.Background())
	tsk := task{
		Task:     t,
		Context:  ctx,
		CancelFn: cancel,
	}

	s.lock.Lock()
	s.tasks[t.TaskID] = &tsk
	s.lock.Unlock()

	switch tr := t.Trigger.(type) {
	case *clitypes.SpaceSyncTriggerOnce:
		triggerOnce(s, &tsk)

	case *clitypes.SpaceSyncTriggerInterval:
		triggerInterval(s, &tsk, tr)

	case *clitypes.SpaceSyncTriggerAt:
		triggerAt(s, &tsk, tr)
	}

	log.Infof("task %v created", t.TaskID)

	return &TaskInfo{
		Task: t,
	}, nil
}

func (s *SpaceSyncer) CancelTask(taskID clitypes.SpaceSyncTaskID) {
	log := logger.WithField("Mod", logMod)

	s.lock.Lock()
	defer s.lock.Unlock()

	t := s.tasks[taskID]
	if t == nil {
		log.Infof("task %v not found, cancel aborted", taskID)
		return
	}

	t.CancelFn()
	delete(s.tasks, taskID)

	err := s.db.SpaceSyncTask().Delete(s.db.DefCtx(), taskID)
	if err != nil {
		log.Warnf("delete task %v from db: %v", taskID, err)
	}

	log.Infof("task %v canceled", taskID)
}

func (s *SpaceSyncer) GetTask(taskID clitypes.SpaceSyncTaskID) *clitypes.SpaceSyncTask {
	s.lock.Lock()
	defer s.lock.Unlock()

	tsk := s.tasks[taskID]
	if tsk == nil {
		return nil
	}

	// TODO 考虑复制一份状态，防止修改
	t := tsk.Task
	return &t
}

type TaskInfo struct {
	Task clitypes.SpaceSyncTask
}

type task struct {
	Task     clitypes.SpaceSyncTask
	Context  context.Context
	CancelFn func()
}