// Package fileparse define related functions for comtrade data processing
package fileparse

import (
	"context"
	"os"
	"path/filepath"
	"sync"

	"wave_record/constant"

	"github.com/fsnotify/fsnotify"
	"github.com/panjf2000/ants/v2"
	"go.uber.org/zap"
)

// DirWatch define function for monitoring directories and passing add file name to channels
func DirWatch(monitorDir string, addChan chan string) {
	logger := zap.L()

	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		logger.Error("create dir watcher failed:", zap.Error(err))
	}
	defer watcher.Close()

	err = watcher.Add(monitorDir)
	if err != nil {
		logger.Error("add monitor dir failed:", zap.Error(err))
	}

	for {
		select {
		case event, ok := <-watcher.Events:
			if !ok {
				return
			}

			if event.Op&fsnotify.Create == fsnotify.Create {
				logger.Info("file add in watcher dir", zap.String("file_name", event.Name))
				addChan <- event.Name
			}

			if event.Op&fsnotify.Remove == fsnotify.Remove {
				logger.Info("file remove in watcher dir", zap.String("file_name", event.Name))
			}
		case err, ok := <-watcher.Errors:
			if !ok {
				logger.Error("monitor watcher error channel closed", zap.Bool("channel_status", ok))
				return
			}

			logger.Error("monitor watcher error occurred", zap.Error(err))
		}
	}
}

// TraverseMonitorDir define function for traverse the files existing in the directory
func TraverseMonitorDir(ctx context.Context, monitorDir string, dbName string, comtradeMap *sync.Map, addChan chan string, delChan chan string, pool *ants.PoolWithFunc) {
	logger := zap.L()
	err := filepath.Walk(monitorDir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			logger.Error("accessing a path failed", zap.Error(err))
			return err
		}

		fileSuffix := filepath.Ext(path)
		if !info.IsDir() && fileSuffix == constant.ConfigFileSuffix {
			processComtradeFile(ctx, path, monitorDir, dbName, comtradeMap, addChan, delChan, pool, logger)
		}
		return nil
	})
	if err != nil {
		logger.Error("traversing files that already exist in the monitor directory failed", zap.Error(err))
	}
}