package raid

import (
	"bufio"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"strings"
)

// Get the next avaible RAID array name
func GetNextAvailableMDDevice() (string, error) {
	for i := 0; i < 100; i++ {
		mdDevice := fmt.Sprintf("/dev/md%d", i)
		if _, err := os.Stat(mdDevice); os.IsNotExist(err) {
			return mdDevice, nil
		}
	}

	return "", fmt.Errorf("no available /dev/mdX devices found")
}

// DANGER: Wipe the whole disk given the disk path
func (m *Manager) WipeDisk(diskPath string) error {
	// Unmount the disk
	isMounted, _ := DeviceIsMounted(diskPath)
	if isMounted {
		umountCmd := exec.Command("sudo", "umount", diskPath)
		if err := umountCmd.Run(); err != nil {
			return fmt.Errorf("error unmounting disk %s: %v", diskPath, err)
		}
	}

	// Wipe all filesystem signatures on the entire disk
	wipeCmd := exec.Command("sudo", "wipefs", "--all", "--force", diskPath)
	if err := wipeCmd.Run(); err != nil {
		return fmt.Errorf("error wiping filesystem signatures on %s: %v", diskPath, err)
	}

	return nil
}

// ClearSuperblock clears the superblock of the specified disk.
func (m *Manager) ClearSuperblock(devicePath string) error {
	isMounted, err := DeviceIsMounted(devicePath)
	if err != nil {
		return errors.New("unable to validate if the device is unmounted: " + err.Error())
	}
	if isMounted {
		return errors.New("target device is mounted. Make sure it is unmounted before clearing")
	}
	cmd := exec.Command("sudo", "mdadm", "--zero-superblock", devicePath)

	err = cmd.Run()
	if err != nil {
		return fmt.Errorf("error clearing superblock: %v", err)
	}

	return nil
}

// Check if a device is mounted given the path name, like /dev/sdc
func DeviceIsMounted(devicePath string) (bool, error) {
	// Open the mountinfo file
	file, err := os.Open("/proc/mounts")
	if err != nil {
		return false, fmt.Errorf("error opening /proc/mounts: %v", err)
	}
	defer file.Close()

	// Scan the mountinfo file line by line
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := scanner.Text()
		fields := strings.Fields(line)
		if len(fields) >= 2 && fields[0] == devicePath {
			// Device is mounted
			return true, nil
		}
	}

	// Device is not mounted
	return false, nil
}