//go:build linux

package storage

import (
	"bytes"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"
)

// FormatAndMount formats a disk/partition and mounts it.
// Progress updates are sent on the progress channel.
// Returns the final mount path on success.
func FormatAndMount(req FormatRequest, progress chan<- FormatProgress) (string, error) {
	send := func(step, msg string, pct int) {
		progress <- FormatProgress{Step: step, Message: msg, Percent: pct}
	}
	fail := func(step, msg string, err error) error {
		errStr := ""
		if err != nil {
			errStr = err.Error()
		}
		progress <- FormatProgress{Step: "error", Message: msg, Error: errStr, Percent: 0}
		return fmt.Errorf("%s: %w", msg, err)
	}

	mountPath := "/mnt/" + req.MountName

	// --- Step 1: Validate ---
	send("validating", "Eszköz ellenőrzése...", 5)

	if err := ValidateMountName(req.MountName); err != nil {
		return "", fail("validating", "Érvénytelen csatlakoztatási név", err)
	}
	if _, err := os.Stat(HostDevicePath(req.DevicePath)); err != nil {
		return "", fail("validating", "Az eszköz nem létezik: "+req.DevicePath, err)
	}

	isSystem, err := IsSystemDisk(req.DevicePath)
	if err != nil {
		return "", fail("validating", "Rendszermeghajtó ellenőrzése sikertelen", err)
	}
	if isSystem {
		return "", fail("validating", "Ez a rendszermeghajtó — nem formázható!", fmt.Errorf("device is system disk"))
	}

	mounted, err := IsDeviceMounted(req.DevicePath)
	if err != nil {
		return "", fail("validating", "Csatlakoztatási állapot ellenőrzése sikertelen", err)
	}
	if mounted {
		return "", fail("validating", "Az eszköz már csatlakoztatva van", fmt.Errorf("device already mounted"))
	}

	inUse, err := IsMountPathInUse(mountPath)
	if err != nil {
		return "", fail("validating", "Csatlakoztatási útvonal ellenőrzése sikertelen", err)
	}
	if inUse {
		return "", fail("validating", "A csatlakoztatási útvonal már használatban van: "+mountPath, fmt.Errorf("mount path in use"))
	}

	send("validating", "Ellenőrzés kész", 10)

	// --- Step 2: Partition (if requested) ---
	partDev := req.DevicePath
	if req.CreatePartition {
		// Wipe existing partition table and filesystem signatures first
		send("partitioning", fmt.Sprintf("wipefs -a %s ...", HostDevicePath(req.DevicePath)), 12)
		_ = exec.Command("wipefs", "-a", HostDevicePath(req.DevicePath)).Run()
		time.Sleep(500 * time.Millisecond)

		// Create GPT with single partition spanning whole disk.
		// ",," = start=default, size=default(fill disk), type=default(Linux filesystem GUID).
		// --force: overwrite even if device appears busy.
		// --wipe always: wipe filesystem signatures from newly created partitions.
		send("partitioning", fmt.Sprintf("sfdisk --force --wipe always %s ...", HostDevicePath(req.DevicePath)), 15)
		sfdiskInput := "label: gpt\n,,\n"
		cmd := exec.Command("sfdisk", "--force", "--wipe", "always", HostDevicePath(req.DevicePath))
		cmd.Stdin = strings.NewReader(sfdiskInput)
		if out, err := cmd.CombinedOutput(); err != nil {
			return "", fail("partitioning", "Partícionálás sikertelen: "+string(out), err)
		}

		_ = exec.Command("partprobe", HostDevicePath(req.DevicePath)).Run()
		time.Sleep(2 * time.Second)

		partDev = req.DevicePath + "1"
		if strings.Contains(req.DevicePath, "nvme") {
			partDev = req.DevicePath + "p1"
		}
		if _, err := os.Stat(HostDevicePath(partDev)); err != nil {
			return "", fail("partitioning", "Partíció nem található a létrehozás után: "+partDev, err)
		}

		send("partitioning", "Partíció létrehozva: "+partDev, 25)
	}

	// --- Step 3: Format ---
	// Use ASCII-safe mount name for ext4 filesystem label (16-byte limit).
	// The display label (req.Label) stays in settings.json for the UI.
	fsLabel := req.MountName
	if len(fsLabel) > 16 {
		fsLabel = fsLabel[:16]
	}

	send("formatting", fmt.Sprintf("mkfs.ext4 -L %s -F %s ...", fsLabel, HostDevicePath(partDev)), 30)
	mkfsCmd := exec.Command("mkfs.ext4", "-L", fsLabel, "-F", HostDevicePath(partDev))
	var mkfsOut bytes.Buffer
	mkfsCmd.Stdout = &mkfsOut
	mkfsCmd.Stderr = &mkfsOut
	if err := mkfsCmd.Run(); err != nil {
		return "", fail("formatting", "Formázás sikertelen: "+mkfsOut.String(), err)
	}

	send("formatting", "Formázás kész", 60)

	// --- Step 4: Mount ---
	if err := os.MkdirAll(mountPath, 0755); err != nil {
		return "", fail("mounting", "Csatlakoztatási mappa nem hozható létre: "+mountPath, err)
	}

	send("mounting", fmt.Sprintf("UUID lekérése: blkid %s ...", HostDevicePath(partDev)), 65)
	uuidOut, err := exec.Command("blkid", "-s", "UUID", "-o", "value", HostDevicePath(partDev)).Output()
	if err != nil {
		return "", fail("mounting", "UUID lekérése sikertelen", err)
	}
	uuid := strings.TrimSpace(string(uuidOut))
	if uuid == "" {
		return "", fail("mounting", "UUID üres a formázás után", fmt.Errorf("empty UUID"))
	}

	// Backup fstab (non-fatal)
	_ = BackupFstab(FstabPath)

	if err := AppendFstabEntry(FstabPath, uuid, mountPath, "ext4", "defaults,nofail,noatime"); err != nil {
		return "", fail("mounting", "fstab bejegyzés hozzáadása sikertelen", err)
	}

	// Mount by device path explicitly — container's /etc/fstab != host fstab,
	// so "mount /mnt/hdd_1" (fstab lookup) won't work.
	send("mounting", fmt.Sprintf("mount -t ext4 %s %s ...", HostDevicePath(partDev), mountPath), 70)
	if out, err := exec.Command("mount", "-t", "ext4", "-o", "defaults,noatime",
		HostDevicePath(partDev), mountPath).CombinedOutput(); err != nil {
		return "", fail("mounting", "Csatlakoztatás sikertelen: "+string(out), err)
	}

	// Verify mount actually worked (don't just trust exit code)
	verifyOut, verifyErr := exec.Command("findmnt", "-n", "-o", "SOURCE", "--target", mountPath).Output()
	if verifyErr != nil || strings.TrimSpace(string(verifyOut)) == "" {
		return "", fail("mounting", "A csatlakoztatás nem ellenőrizhető: mount sikerült, de a meghajtó nem látható",
			fmt.Errorf("mount point %s not found after mount", mountPath))
	}

	send("mounting", "Csatlakoztatva: "+mountPath, 80)

	// --- Step 5: Permissions + subdirs ---
	send("permissions", "Mappák létrehozása és jogosultságok beállítása...", 85)

	_ = exec.Command("chown", "1000:1000", mountPath).Run()

	for _, subdir := range []string{"storage", "Dokumentumok"} {
		dir := filepath.Join(mountPath, subdir)
		if err := os.MkdirAll(dir, 0755); err == nil {
			_ = exec.Command("chown", "1000:1000", dir).Run()
		}
	}

	send("done", "Meghajtó sikeresen inicializálva: "+mountPath, 100)

	return mountPath, nil
}

// GetDeviceUUID returns the UUID of a block device/partition.
func GetDeviceUUID(devicePath string) (string, error) {
	out, err := exec.Command("blkid", "-s", "UUID", "-o", "value", HostDevicePath(devicePath)).Output()
	if err != nil {
		return "", err
	}
	return strings.TrimSpace(string(out)), nil
}

// ReadFstab reads the current fstab content.
func ReadFstab() (string, error) {
	data, err := os.ReadFile(FstabPath)
	if err != nil {
		data, err = os.ReadFile("/etc/fstab")
		if err != nil {
			return "", err
		}
	}
	return string(data), nil
}