package cmd

import (
	"bytes"
	"context"
	"fmt"
	"log"
	"math"
	"net/smtp"
	"os"
	"strings"
	"time"

	"gitea.urkob.com/urko/backblaze-backup/internal/services/backblaze"
	"gitea.urkob.com/urko/backblaze-backup/internal/services/email"
	"gitea.urkob.com/urko/backblaze-backup/kit"
	"gitea.urkob.com/urko/backblaze-backup/kit/config"
	"github.com/sirupsen/logrus"
	"github.com/spf13/cobra"
)

var Check = &cobra.Command{
	Use:   "check",
	Short: "Compares local backup files with those in a Backblaze B2 bucket and sends a summary email.",
	Long: `This command compares the list of files in a local backup directory against the files in a specified Backblaze B2 bucket. 
	The operation is performed concurrently and is time-bound, set by default to 5 minutes. 
	If discrepancies are found, i.e., some files exist only locally or only on the cloud, these are logged and sent via email as attachments. 

	The email contains two text attachments:
	- 'Local-Files-Not-In-B2.txt': Lists files that are in the local backup directory but not in the B2 bucket.
	- 'B2-Files-Not-In-Local.txt': Lists files that are in the B2 bucket but not in the local backup directory.

	The command requires two flags:
	- '--dir': The path of the local backup directory
	- '--bucket': The name of the Backblaze B2 bucket

	An environment variable 'BACKBLAZE_ENV' can be set to 'dev' to load environment variables from a .env file in the root directory.`,
	Run: func(cmd *cobra.Command, args []string) {
		ctx, cancel := context.WithTimeout(context.Background(), time.Minute*5) // or any appropriate time
		defer cancel()

		log.SetFlags(log.Ldate | log.Lmicroseconds)
		backupDir, err := cmd.Flags().GetString("dir")
		if err != nil {
			panic(fmt.Errorf("dir %w", err))
		}
		bucketName, err := cmd.Flags().GetString("bucket")
		if err != nil {
			panic(fmt.Errorf("bucket %w", err))
		}

		envFile := ""
		if os.Getenv("BACKBLAZE_ENV") == "dev" {
			envFile = kit.RootDir() + "/.env"
		}

		cfg := config.NewConfig(envFile)
		mailSrv := email.NewMailService(email.MailServiceConfig{
			Auth: smtp.PlainAuth("", cfg.MailUser, cfg.MailPassword, cfg.MailHost),
			Host: cfg.MailHost,
			Port: cfg.MailPort,
			From: cfg.MailFrom,
		},
		)
		logger := logrus.New()
		logger.SetLevel(logrus.Level(cfg.LogLevel))

		b, err := backblaze.NewBackBlaze(ctx, logger, cfg.BbId, cfg.BbKey)
		if err != nil {
			panic(fmt.Errorf("NewBackBlaze %w", err))
		}

		logger.Info("start check")
		defer logger.Info("end check")

		localChan := make(chan backblaze.B2Local)
		b2Chan := make(chan backblaze.B2Local)
		countChan := make(chan int, 1)
		go b.CompareConcurrent(ctx, backupDir, bucketName, localChan, b2Chan, countChan)

		reportBuilder := strings.Builder{}
		reportBuilder.WriteString(fmt.Sprintf("Local files within `%s` path already in `%s` bucket:\n", backupDir, bucketName))

		countLocal := 0
		countB2 := 0

		cloudBuilder := strings.Builder{}
		cloudBuilder.WriteString(fmt.Sprintf("B2 files within `%s` bucket\n", bucketName))
		cloudBuilder.WriteString("| B2 File Name                                             | Size             | ModTime                        | Status                                   |\n")
		cloudBuilder.WriteString("|----------------------------------------------------------|------------------|--------------------------------|------------------------------------------\n")
		countNotInLocal := 0

		localBuilder := strings.Builder{}
		localBuilder.WriteString(fmt.Sprintf("Local files in `%s`\n", backupDir))
		localBuilder.WriteString("| Local File Name                                          | Size             | ModTime                        | Status                                   |\n")
		localBuilder.WriteString("|----------------------------------------------------------|------------------|--------------------------------|------------------------------------------\n")
		countNotInCloud := 0

		countOK := 0
	loop:
		for {
			select {
			case <-ctx.Done():
				// Handle the timeout or cancellation
				if ctx.Err() == context.DeadlineExceeded {
					logger.Error("Operation timed out")
				} else if ctx.Err() == context.Canceled {
					logger.Error("Operation canceled")
				}
				break loop
			case countOK = <-countChan:
				logger.Debugln("done chan")
				break loop
			case localMsg, ok := <-localChan:
				if !ok {
					continue
				}
				countLocal++
				logger.Debugln("localChan", localMsg.File)
				writeTableRow(&localBuilder, &countNotInCloud, localMsg.File, localMsg.Err)
			case b2Msg, ok := <-b2Chan:
				if !ok {
					continue
				}
				countB2++
				logger.Debugln("cloudBuilder", b2Msg.File)
				writeTableRow(&cloudBuilder, &countNotInLocal, b2Msg.File, b2Msg.Err)
			}
		}

		reportBuilder.WriteString("\n")
		reportBuilder.WriteString(cloudBuilder.String())
		reportBuilder.WriteString("\n")
		reportBuilder.WriteString(localBuilder.String())

		if err := mailSrv.SendOK(email.EmailWithAttachments{
			To:        cfg.MailTo,
			Bucket:    bucketName,
			BackupDir: backupDir,
			Count: map[string]int{
				"count_ok":           countOK,
				"count_local":        countLocal,
				"count_b2":           countB2,
				"count_not_in_local": countNotInLocal,
				"count_not_in_cloud": countNotInCloud,
			},
			Attachments: []email.EmailAttachment{{File: bytes.NewReader([]byte(reportBuilder.String())), Title: fmt.Sprintf("%s-check-report.txt", bucketName)}},
		}); err != nil {
			panic(fmt.Errorf("error while send email: %w", err))
		}
	},
}

// New function to write a table row
func writeTableRow(builder *strings.Builder, count *int, file backblaze.File, err error) {
	status := "OK"
	if err != nil {
		status = err.Error()
		(*count)++
	}

	builder.WriteString(fmt.Sprintf("| %-56s | %-16s | %-30s | %-40s |\n", file.Path, prettyByteSize(file.Size), file.ModTime.Format("2006-01-02 15:04:05.000"), status))
}

func prettyByteSize(b int) string {
	bf := float64(b)
	for _, unit := range []string{"", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei", "Zi"} {
		if math.Abs(bf) < 1024.0 {
			return fmt.Sprintf("%3.1f%sB", bf, unit)
		}
		bf /= 1024.0
	}
	return fmt.Sprintf("%.1fYiB", bf)
}