package zfs

import (
	"bytes"
	"encoding/json"
	"fmt"
	"os/exec"
	"strconv"
	"strings"
	"time"

	"gitea.avt.data-center.id/othman.suseno/atlas/internal/models"
)

// Service provides ZFS operations
type Service struct {
	zfsPath   string
	zpoolPath string
}

// New creates a new ZFS service
func New() *Service {
	return &Service{
		zfsPath:   "zfs",
		zpoolPath: "zpool",
	}
}

// execCommand executes a shell command and returns output
func (s *Service) execCommand(name string, args ...string) (string, error) {
	cmd := exec.Command(name, args...)
	var stdout, stderr bytes.Buffer
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr

	if err := cmd.Run(); err != nil {
		return "", fmt.Errorf("%s: %v: %s", name, err, stderr.String())
	}

	return strings.TrimSpace(stdout.String()), nil
}

// ListPools returns all ZFS pools
func (s *Service) ListPools() ([]models.Pool, error) {
	output, err := s.execCommand(s.zpoolPath, "list", "-H", "-o", "name,size,allocated,free,health")
	if err != nil {
		return nil, err
	}

	var pools []models.Pool
	lines := strings.Split(output, "\n")
	for _, line := range lines {
		if line == "" {
			continue
		}

		fields := strings.Fields(line)
		if len(fields) < 5 {
			continue
		}

		pool := models.Pool{
			Name:   fields[0],
			Status: "ONLINE", // Default, will be updated from health
			Health: fields[4],
		}

		// Parse sizes (handles K, M, G, T suffixes)
		if size, err := parseSize(fields[1]); err == nil {
			pool.Size = size
		}
		if allocated, err := parseSize(fields[2]); err == nil {
			pool.Allocated = allocated
		}
		if free, err := parseSize(fields[3]); err == nil {
			pool.Free = free
		}

		// Get pool status
		status, _ := s.execCommand(s.zpoolPath, "status", "-x", pool.Name)
		if strings.Contains(status, "all pools are healthy") {
			pool.Status = "ONLINE"
		} else if strings.Contains(status, "DEGRADED") {
			pool.Status = "DEGRADED"
		} else if strings.Contains(status, "FAULTED") {
			pool.Status = "FAULTED"
		}

		// Get creation time
		created, _ := s.execCommand(s.zfsPath, "get", "-H", "-o", "value", "creation", pool.Name)
		if t, err := time.Parse("Mon Jan 2 15:04:05 2006", created); err == nil {
			pool.CreatedAt = t
		}

		pools = append(pools, pool)
	}

	return pools, nil
}

// GetPool returns a specific pool
func (s *Service) GetPool(name string) (*models.Pool, error) {
	pools, err := s.ListPools()
	if err != nil {
		return nil, err
	}

	for _, pool := range pools {
		if pool.Name == name {
			return &pool, nil
		}
	}

	return nil, fmt.Errorf("pool %s not found", name)
}

// CreatePool creates a new ZFS pool
func (s *Service) CreatePool(name string, vdevs []string, options map[string]string) error {
	args := []string{"create"}

	// Add options
	for k, v := range options {
		args = append(args, "-o", fmt.Sprintf("%s=%s", k, v))
	}

	args = append(args, name)
	args = append(args, vdevs...)

	_, err := s.execCommand(s.zpoolPath, args...)
	return err
}

// DestroyPool destroys a ZFS pool
func (s *Service) DestroyPool(name string) error {
	_, err := s.execCommand(s.zpoolPath, "destroy", name)
	return err
}

// ScrubPool starts a scrub operation on a pool
func (s *Service) ScrubPool(name string) error {
	_, err := s.execCommand(s.zpoolPath, "scrub", name)
	return err
}

// GetScrubStatus returns the current scrub status
func (s *Service) GetScrubStatus(name string) (string, error) {
	output, err := s.execCommand(s.zpoolPath, "status", name)
	if err != nil {
		return "", err
	}

	if strings.Contains(output, "scrub in progress") {
		return "in_progress", nil
	}
	if strings.Contains(output, "scrub repaired") {
		return "completed", nil
	}
	return "idle", nil
}

// ListDatasets returns all datasets in a pool (or all if pool is empty)
func (s *Service) ListDatasets(pool string) ([]models.Dataset, error) {
	args := []string{"list", "-H", "-o", "name,type,used,avail,mountpoint"}
	if pool != "" {
		args = append(args, "-r", pool)
	} else {
		args = append(args, "-r")
	}

	output, err := s.execCommand(s.zfsPath, args...)
	if err != nil {
		return nil, err
	}

	var datasets []models.Dataset
	lines := strings.Split(output, "\n")
	for _, line := range lines {
		if line == "" {
			continue
		}

		fields := strings.Fields(line)
		if len(fields) < 5 {
			continue
		}

		fullName := fields[0]
		parts := strings.Split(fullName, "/")
		poolName := parts[0]

		dataset := models.Dataset{
			Name:       fullName,
			Pool:       poolName,
			Type:       fields[1],
			Mountpoint: fields[4],
		}

		if used, err := parseSize(fields[2]); err == nil {
			dataset.Used = used
		}
		if avail, err := parseSize(fields[3]); err == nil {
			dataset.Available = avail
		}
		dataset.Size = dataset.Used + dataset.Available

		// Get creation time
		created, _ := s.execCommand(s.zfsPath, "get", "-H", "-o", "value", "creation", fullName)
		if t, err := time.Parse("Mon Jan 2 15:04:05 2006", created); err == nil {
			dataset.CreatedAt = t
		}

		datasets = append(datasets, dataset)
	}

	return datasets, nil
}

// CreateDataset creates a new ZFS dataset
func (s *Service) CreateDataset(name string, options map[string]string) error {
	args := []string{"create"}

	for k, v := range options {
		args = append(args, "-o", fmt.Sprintf("%s=%s", k, v))
	}

	args = append(args, name)
	_, err := s.execCommand(s.zfsPath, args...)
	return err
}

// DestroyDataset destroys a ZFS dataset
func (s *Service) DestroyDataset(name string, recursive bool) error {
	args := []string{"destroy"}
	if recursive {
		args = append(args, "-r")
	}
	args = append(args, name)
	_, err := s.execCommand(s.zfsPath, args...)
	return err
}

// ListZVOLs returns all ZVOLs
func (s *Service) ListZVOLs(pool string) ([]models.ZVOL, error) {
	args := []string{"list", "-H", "-o", "name,volsize,used", "-t", "volume"}
	if pool != "" {
		args = append(args, "-r", pool)
	} else {
		args = append(args, "-r")
	}

	output, err := s.execCommand(s.zfsPath, args...)
	if err != nil {
		return nil, err
	}

	var zvols []models.ZVOL
	lines := strings.Split(output, "\n")
	for _, line := range lines {
		if line == "" {
			continue
		}

		fields := strings.Fields(line)
		if len(fields) < 3 {
			continue
		}

		fullName := fields[0]
		parts := strings.Split(fullName, "/")
		poolName := parts[0]

		zvol := models.ZVOL{
			Name: fullName,
			Pool: poolName,
		}

		if size, err := parseSize(fields[1]); err == nil {
			zvol.Size = size
		}
		if used, err := parseSize(fields[2]); err == nil {
			zvol.Used = used
		}

		// Get creation time
		created, _ := s.execCommand(s.zfsPath, "get", "-H", "-o", "value", "creation", fullName)
		if t, err := time.Parse("Mon Jan 2 15:04:05 2006", created); err == nil {
			zvol.CreatedAt = t
		}

		zvols = append(zvols, zvol)
	}

	return zvols, nil
}

// CreateZVOL creates a new ZVOL
func (s *Service) CreateZVOL(name string, size uint64, options map[string]string) error {
	args := []string{"create", "-V", fmt.Sprintf("%d", size)}

	for k, v := range options {
		args = append(args, "-o", fmt.Sprintf("%s=%s", k, v))
	}

	args = append(args, name)
	_, err := s.execCommand(s.zfsPath, args...)
	return err
}

// DestroyZVOL destroys a ZVOL
func (s *Service) DestroyZVOL(name string) error {
	_, err := s.execCommand(s.zfsPath, "destroy", name)
	return err
}

// ListDisks returns available disks (read-only)
func (s *Service) ListDisks() ([]map[string]string, error) {
	// Use lsblk to list block devices
	output, err := s.execCommand("lsblk", "-J", "-o", "name,size,type,fstype,mountpoint")
	if err != nil {
		return nil, err
	}

	var result struct {
		BlockDevices []struct {
			Name       string        `json:"name"`
			Size       string        `json:"size"`
			Type       string        `json:"type"`
			FSType     string        `json:"fstype"`
			Mountpoint string        `json:"mountpoint"`
			Children   []interface{} `json:"children"`
		} `json:"blockdevices"`
	}

	if err := json.Unmarshal([]byte(output), &result); err != nil {
		return nil, err
	}

	var disks []map[string]string
	for _, dev := range result.BlockDevices {
		if dev.Type == "disk" && dev.FSType == "" && dev.Mountpoint == "" {
			disks = append(disks, map[string]string{
				"name": dev.Name,
				"size": dev.Size,
				"path": "/dev/" + dev.Name,
			})
		}
	}

	return disks, nil
}

// parseSize converts human-readable size to bytes
func parseSize(s string) (uint64, error) {
	s = strings.TrimSpace(s)
	if s == "-" || s == "" {
		return 0, nil
	}

	multiplier := uint64(1)
	suffix := strings.ToUpper(s[len(s)-1:])

	switch suffix {
	case "K":
		multiplier = 1024
		s = s[:len(s)-1]
	case "M":
		multiplier = 1024 * 1024
		s = s[:len(s)-1]
	case "G":
		multiplier = 1024 * 1024 * 1024
		s = s[:len(s)-1]
	case "T":
		multiplier = 1024 * 1024 * 1024 * 1024
		s = s[:len(s)-1]
	case "P":
		multiplier = 1024 * 1024 * 1024 * 1024 * 1024
		s = s[:len(s)-1]
	default:
		// Check if last char is a digit
		if suffix[0] < '0' || suffix[0] > '9' {
			return 0, fmt.Errorf("unknown suffix: %s", suffix)
		}
	}

	// Handle decimal values (e.g., "1.5G")
	if strings.Contains(s, ".") {
		val, err := strconv.ParseFloat(s, 64)
		if err != nil {
			return 0, err
		}
		return uint64(val * float64(multiplier)), nil
	}

	val, err := strconv.ParseUint(s, 10, 64)
	if err != nil {
		return 0, err
	}

	return val * multiplier, nil
}