//go:build linux

package storage

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

// MountRaw temporarily mounts a partition at a staging path for browsing.
// The partition is mounted read-only so the user can inspect its contents
// before choosing a subfolder for the final bind mount.
// Returns the raw mount path (e.g., "/mnt/.felhom-raw/hdd_1").
func MountRaw(devicePath string) (string, error) {
	// --- Validate device path ---
	if !strings.HasPrefix(devicePath, "/dev/") {
		return "", fmt.Errorf("érvénytelen eszközútvonal: /dev/-vel kell kezdődnie")
	}
	if strings.Contains(devicePath, "..") {
		return "", fmt.Errorf("érvénytelen eszközútvonal: nem tartalmazhat ..-t")
	}
	if _, err := os.Stat(HostDevicePath(devicePath)); err != nil {
		return "", fmt.Errorf("az eszköz nem létezik: %s", devicePath)
	}

	isSystem, err := IsSystemDisk(devicePath)
	if err != nil {
		return "", fmt.Errorf("rendszermeghajtó ellenőrzése sikertelen: %w", err)
	}
	if isSystem {
		return "", fmt.Errorf("ez a rendszermeghajtó — nem csatolható")
	}

	mounted, err := IsDeviceMounted(devicePath)
	if err != nil {
		return "", fmt.Errorf("csatlakoztatási állapot ellenőrzése sikertelen: %w", err)
	}
	if mounted {
		return "", fmt.Errorf("az eszköz már csatlakoztatva van")
	}

	// --- Detect filesystem ---
	fsType, err := getBlkidValue(devicePath, "TYPE")
	if err != nil || fsType == "" {
		return "", fmt.Errorf("nincs fájlrendszer az eszközön (%s) — használja az inicializálás varázslót", devicePath)
	}

	// Get label for naming the raw mount directory
	label, _ := getBlkidValue(devicePath, "LABEL")
	uuid, _ := getBlkidValue(devicePath, "UUID")

	// Choose a directory name: prefer label, fall back to UUID prefix
	dirName := label
	if dirName == "" && uuid != "" {
		if len(uuid) > 8 {
			dirName = uuid[:8]
		} else {
			dirName = uuid
		}
	}
	if dirName == "" {
		dirName = filepath.Base(devicePath) // "sdb1"
	}

	rawPath := filepath.Join(RawMountBase, dirName)

	// Check if already raw-mounted (idempotent)
	if inUse, _ := IsMountPathInUse(rawPath); inUse {
		return rawPath, nil
	}

	// Create staging directory
	if err := os.MkdirAll(rawPath, 0755); err != nil {
		return "", fmt.Errorf("nem hozható létre a staging mappa: %w", err)
	}

	// Mount read-only for browsing
	if out, err := exec.Command("mount", "-t", fsType, "-o", "defaults,noatime,ro",
		HostDevicePath(devicePath), rawPath).CombinedOutput(); err != nil {
		os.Remove(rawPath)
		return "", fmt.Errorf("csatlakoztatás sikertelen: %s — %w", string(out), err)
	}

	return rawPath, nil
}

// ListDirectories returns the subdirectories at the given path.
// Only directories are returned; files, symlinks, and "lost+found" are excluded.
func ListDirectories(basePath string) ([]DirEntry, error) {
	// Security: only allow browsing under the raw mount staging area
	cleanPath := filepath.Clean(basePath)
	if !strings.HasPrefix(cleanPath, RawMountBase) {
		return nil, fmt.Errorf("érvénytelen útvonal: csak %s alatti mappák böngészhetők", RawMountBase)
	}

	entries, err := os.ReadDir(cleanPath)
	if err != nil {
		return nil, fmt.Errorf("mappa olvasása sikertelen: %w", err)
	}

	var dirs []DirEntry
	for _, e := range entries {
		if !e.IsDir() {
			continue
		}
		name := e.Name()
		// Skip lost+found and hidden directories
		if name == "lost+found" || strings.HasPrefix(name, ".") {
			continue
		}
		fullPath := filepath.Join(cleanPath, name)

		// Check if this directory has subdirectories
		hasChildren := false
		if subEntries, err := os.ReadDir(fullPath); err == nil {
			for _, se := range subEntries {
				if se.IsDir() && se.Name() != "lost+found" && !strings.HasPrefix(se.Name(), ".") {
					hasChildren = true
					break
				}
			}
		}

		dirs = append(dirs, DirEntry{
			Name:        name,
			Path:        fullPath,
			HasChildren: hasChildren,
		})
	}
	return dirs, nil
}

// CreateDirectory creates a new directory at basePath/name.
// The raw mount is remounted read-write if needed.
func CreateDirectory(basePath, name string) (string, error) {
	// Security: only allow creation under the raw mount staging area
	cleanBase := filepath.Clean(basePath)
	if !strings.HasPrefix(cleanBase, RawMountBase) {
		return "", fmt.Errorf("érvénytelen útvonal: csak %s alatti mappák módosíthatók", RawMountBase)
	}

	// Validate directory name (same rules as mount names)
	if err := ValidateMountName(name); err != nil {
		return "", fmt.Errorf("érvénytelen mappanév: %w", err)
	}

	targetPath := filepath.Join(cleanBase, name)

	// Check if already exists
	if fi, err := os.Stat(targetPath); err == nil {
		if fi.IsDir() {
			return "", fmt.Errorf("a mappa már létezik: %s", name)
		}
		return "", fmt.Errorf("a cél már létezik és nem mappa")
	}

	// Remount read-write (the raw mount is initially read-only)
	rawMountPoint := findRawMountPoint(cleanBase)
	if rawMountPoint != "" {
		_ = exec.Command("mount", "-o", "remount,rw", rawMountPoint).Run()
	}

	if err := os.MkdirAll(targetPath, 0755); err != nil {
		return "", fmt.Errorf("mappa létrehozása sikertelen: %w", err)
	}
	_ = exec.Command("chown", "1000:1000", targetPath).Run()

	return targetPath, nil
}

// FinalizeAttach creates the bind mount, fstab entries, and sets up permissions.
// Progress updates are sent on the progress channel.
// Returns the final mount path (/mnt/<name>) on success.
func FinalizeAttach(req AttachRequest, 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)
	}
	dbg := func(format string, args ...interface{}) {
		if req.Logger != nil && req.Debug {
			req.Logger.Printf("[DEBUG] FinalizeAttach: "+format, args...)
		}
	}

	mountPath := "/mnt/" + req.MountName
	dbg("starting: device=%s mountName=%s subPath=%s", req.DevicePath, req.MountName, req.SubPath)

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

	if err := ValidateMountName(req.MountName); err != nil {
		return "", fail("validating", "Érvénytelen csatlakoztatási név", err)
	}
	if !strings.HasPrefix(req.DevicePath, "/dev/") {
		return "", fail("validating", "Érvénytelen eszközútvonal", fmt.Errorf("must start with /dev/"))
	}
	if strings.Contains(req.DevicePath, "..") {
		return "", fail("validating", "Érvénytelen eszközútvonal", fmt.Errorf("must not contain .."))
	}

	// Validate subpath is under the raw mount area
	cleanSub := filepath.Clean(req.SubPath)
	if !strings.HasPrefix(cleanSub, RawMountBase) {
		return "", fail("validating", "Érvénytelen almappa útvonal", fmt.Errorf("subpath must be under %s", RawMountBase))
	}
	if _, err := os.Stat(cleanSub); err != nil {
		return "", fail("validating", "Az almappa nem létezik: "+cleanSub, err)
	}

	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", 15)

	// --- Step 2: Ensure raw mount is read-write ---
	send("mounting", "Fájlrendszer előkészítése...", 20)

	rawMountPoint := findRawMountPoint(cleanSub)
	if rawMountPoint != "" {
		_ = exec.Command("mount", "-o", "remount,rw", rawMountPoint).Run()
	}

	// --- Step 3: Get device info for fstab ---
	fsType, _ := getBlkidValue(req.DevicePath, "TYPE")
	if fsType == "" {
		fsType = "ext4" // fallback
	}
	uuid, err := getBlkidValue(req.DevicePath, "UUID")
	if err != nil || uuid == "" {
		return "", fail("mounting", "UUID lekérése sikertelen", fmt.Errorf("empty UUID for %s", req.DevicePath))
	}

	// Determine the raw mount directory name (the direct child of RawMountBase)
	relFromBase := strings.TrimPrefix(cleanSub, RawMountBase+"/")
	rawDirName := strings.SplitN(relFromBase, "/", 2)[0]
	rawMountPath := filepath.Join(RawMountBase, rawDirName)

	// Determine the subfolder relative to the raw mount
	subRel := strings.TrimPrefix(cleanSub, rawMountPath)
	subRel = strings.TrimPrefix(subRel, "/")

	dbg("raw mount path: %s, sub relative: %q", rawMountPath, subRel)
	send("mounting", "fstab bejegyzések hozzáadása...", 35)

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

	// Fstab entry 1: raw partition mount
	// Use nofail so a missing disk doesn't block boot
	dbg("fstab entry 1: UUID=%s → %s (fstype=%s)", uuid, rawMountPath, fsType)
	if err := AppendFstabEntry(FstabPath, uuid, rawMountPath, fsType, "defaults,nofail,noatime"); err != nil {
		dbg("fstab raw mount entry failed: %v", err)
		return "", fail("mounting", "fstab bejegyzés hozzáadása sikertelen (raw mount)", err)
	}

	// Fstab entry 2: bind mount from subfolder to final path
	bindSource := cleanSub
	dbg("fstab entry 2: bind %s → %s", bindSource, mountPath)
	if err := appendBindFstabEntry(FstabPath, bindSource, mountPath); err != nil {
		dbg("fstab bind entry failed: %v", err)
		// Roll back the raw mount fstab entry
		_ = RemoveFstabEntry(FstabPath, uuid)
		return "", fail("mounting", "fstab bejegyzés hozzáadása sikertelen (bind mount)", err)
	}

	// --- Step 4: Create bind mount ---
	send("mounting", fmt.Sprintf("Bind mount: %s → %s ...", cleanSub, mountPath), 50)

	if err := os.MkdirAll(mountPath, 0755); err != nil {
		_ = RemoveFstabEntry(FstabPath, uuid)
		_ = removeBindFstabEntry(FstabPath, mountPath)
		return "", fail("mounting", "Csatlakoztatási mappa nem hozható létre: "+mountPath, err)
	}

	dbg("bind mount: mount --bind %s %s", cleanSub, mountPath)
	if out, err := exec.Command("mount", "--bind", cleanSub, mountPath).CombinedOutput(); err != nil {
		dbg("bind mount failed: %s", string(out))
		_ = RemoveFstabEntry(FstabPath, uuid)
		_ = removeBindFstabEntry(FstabPath, mountPath)
		return "", fail("mounting", "Bind mount sikertelen: "+string(out), err)
	}

	// Verify bind mount
	dbg("verifying bind mount with findmnt")
	verifyOut, verifyErr := exec.Command("findmnt", "-n", "-o", "SOURCE", "--target", mountPath).Output()
	if verifyErr != nil || strings.TrimSpace(string(verifyOut)) == "" {
		dbg("bind mount verification failed: findmnt returned %q err=%v", string(verifyOut), verifyErr)
		_ = exec.Command("umount", mountPath).Run()
		_ = RemoveFstabEntry(FstabPath, uuid)
		_ = removeBindFstabEntry(FstabPath, mountPath)
		return "", fail("mounting", "A bind mount nem ellenőrizhető", fmt.Errorf("mount point %s not found after bind mount", mountPath))
	}
	dbg("bind mount verified: source=%q", strings.TrimSpace(string(verifyOut)))

	send("mounting", "Csatlakoztatva: "+mountPath, 70)

	// --- Step 5: Permissions + subdirs ---
	send("permissions", "Mappák létrehozása és jogosultságok beállítása...", 80)

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

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

	dbg("attach completed successfully: %s", mountPath)
	send("done", "Meghajtó sikeresen csatolva: "+mountPath, 100)

	return mountPath, nil
}

// CleanupRawMount unmounts a staging raw mount and removes its directory.
// Called when the user cancels the attach wizard.
func CleanupRawMount(rawPath string) error {
	cleanPath := filepath.Clean(rawPath)
	if !strings.HasPrefix(cleanPath, RawMountBase) {
		return fmt.Errorf("érvénytelen útvonal: csak %s alatti csatlakozások távolíthatók el", RawMountBase)
	}

	// Unmount
	_ = exec.Command("umount", cleanPath).Run()

	// Remove empty directory
	_ = os.Remove(cleanPath)

	return nil
}

// CleanupStaleRawMounts finds and removes raw mounts that have no corresponding
// bind mount — i.e., leftovers from an interrupted attach wizard.
// A raw mount is considered "in use" if fstab has a bind entry sourcing from it.
func CleanupStaleRawMounts() {
	data, err := os.ReadFile("/proc/mounts")
	if err != nil {
		return
	}

	// Read fstab to check for bind mount entries
	fstabData, _ := os.ReadFile(FstabPath)
	fstabLines := strings.Split(string(fstabData), "\n")

	for _, line := range strings.Split(string(data), "\n") {
		fields := strings.Fields(line)
		if len(fields) < 2 {
			continue
		}
		mountPoint := fields[1]
		if !strings.HasPrefix(mountPoint, RawMountBase+"/") {
			continue
		}
		// Only consider direct children of RawMountBase (e.g., /mnt/.felhom-raw/hdd_1)
		rel := strings.TrimPrefix(mountPoint, RawMountBase+"/")
		if strings.Contains(rel, "/") {
			continue
		}

		// Check if any fstab bind entry sources from this raw mount path
		inUse := false
		for _, fl := range fstabLines {
			fl = strings.TrimSpace(fl)
			if fl == "" || strings.HasPrefix(fl, "#") {
				continue
			}
			if strings.Contains(fl, "bind") && strings.HasPrefix(fl, mountPoint) {
				inUse = true
				break
			}
		}

		if !inUse {
			_ = exec.Command("umount", mountPoint).Run()
			_ = os.Remove(mountPoint)
		}
	}
}

// --- helpers ---

// getBlkidValue runs blkid to get a single value (TYPE, UUID, LABEL) for a device.
func getBlkidValue(devicePath, tag string) (string, error) {
	out, err := exec.Command("blkid", "-o", "value", "-s", tag, HostDevicePath(devicePath)).Output()
	if err != nil {
		return "", err
	}
	return strings.TrimSpace(string(out)), nil
}

// findRawMountPoint finds the mount point for a path under RawMountBase.
// E.g., for "/mnt/.felhom-raw/hdd_1/some/sub" it returns "/mnt/.felhom-raw/hdd_1".
func findRawMountPoint(path string) string {
	cleanPath := filepath.Clean(path)
	if !strings.HasPrefix(cleanPath, RawMountBase+"/") {
		return ""
	}
	rel := strings.TrimPrefix(cleanPath, RawMountBase+"/")
	parts := strings.SplitN(rel, "/", 2)
	if len(parts) == 0 || parts[0] == "" {
		return ""
	}
	return filepath.Join(RawMountBase, parts[0])
}

// appendBindFstabEntry appends a bind mount fstab entry.
func appendBindFstabEntry(fstabPath, source, target string) error {
	existing, err := os.ReadFile(fstabPath)
	if err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("cannot read fstab: %w", err)
	}

	entry := fmt.Sprintf("\n# Bind mount (auto-generated by felhom-controller)\n%s\t%s\tnone\tbind,nofail\t0 0\n", source, target)
	newContent := append(existing, []byte(entry)...)

	return safeWriteFile(fstabPath, newContent, 0644)
}

// removeBindFstabEntry removes the bind mount fstab entry for the given target mount path.
func removeBindFstabEntry(fstabPath, targetMountPath string) error {
	data, err := os.ReadFile(fstabPath)
	if err != nil {
		return fmt.Errorf("cannot read fstab: %w", err)
	}

	lines := strings.Split(string(data), "\n")
	var kept []string
	for i := 0; i < len(lines); i++ {
		line := lines[i]
		// Remove both the comment line and the bind mount line
		if strings.Contains(line, "Bind mount (auto-generated by felhom-controller)") {
			// Check if the next line is the actual bind entry for this target
			if i+1 < len(lines) && fstabMatchesTarget(lines[i+1], targetMountPath) {
				i++ // skip the bind line too
				continue
			}
		}
		if fstabMatchesTarget(line, targetMountPath) && strings.Contains(line, "bind") {
			continue
		}
		kept = append(kept, line)
	}

	return safeWriteFile(fstabPath, []byte(strings.Join(kept, "\n")), 0644)
}

// fstabMatchesTarget parses an fstab line and checks if the mount target (field 2) matches exactly.
func fstabMatchesTarget(line, target string) bool {
	line = strings.TrimSpace(line)
	if line == "" || strings.HasPrefix(line, "#") {
		return false
	}
	fields := strings.Fields(line)
	if len(fields) < 2 {
		return false
	}
	return fields[1] == target
}