package zfs

import (
	"bytes"
	"encoding/json"
	"fmt"
	"log"
	"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 {
	// Find full paths to zfs and zpool commands
	zfsPath := findCommandPath("zfs")
	zpoolPath := findCommandPath("zpool")

	return &Service{
		zfsPath:   zfsPath,
		zpoolPath: zpoolPath,
	}
}

// findCommandPath finds the full path to a command
func findCommandPath(cmd string) string {
	// Try which first
	if output, err := exec.Command("which", cmd).Output(); err == nil {
		path := strings.TrimSpace(string(output))
		if path != "" {
			return path
		}
	}

	// Try LookPath
	if path, err := exec.LookPath(cmd); err == nil {
		return path
	}

	// Fallback to command name (will use PATH)
	return cmd
}

// execCommand executes a shell command and returns output
// For ZFS operations that require elevated privileges, it uses sudo
func (s *Service) execCommand(name string, args ...string) (string, error) {
	// Commands that require root privileges
	privilegedCommands := []string{"zpool", "zfs"}
	useSudo := false

	for _, cmd := range privilegedCommands {
		if strings.Contains(name, cmd) {
			useSudo = true
			break
		}
	}

	var cmd *exec.Cmd
	if useSudo {
		// Use sudo -n (non-interactive) for privileged commands
		// This prevents password prompts and will fail if sudoers is not configured
		sudoArgs := append([]string{"-n", name}, args...)
		cmd = exec.Command("sudo", sudoArgs...)
	} else {
		cmd = exec.Command(name, args...)
	}

	var stdout, stderr bytes.Buffer
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr

	err := cmd.Run()
	if err != nil && useSudo {
		// If sudo failed, try running the command directly
		// (user might already have permissions or be root)
		directCmd := exec.Command(name, args...)
		var directStdout, directStderr bytes.Buffer
		directCmd.Stdout = &directStdout
		directCmd.Stderr = &directStderr

		if directErr := directCmd.Run(); directErr == nil {
			// Direct execution succeeded, return that result
			return strings.TrimSpace(directStdout.String()), nil
		}
		// Both sudo and direct failed, return the original sudo error
		return "", fmt.Errorf("%s: %v: %s", name, err, stderr.String())
	}

	if 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 empty slice instead of nil to ensure JSON encodes as [] not null
		return []models.Pool{}, err
	}

	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"}

	if options == nil {
		options = make(map[string]string)
	}

	// Add -f flag to force creation even if devices have existing filesystems
	// This handles cases where devices are "in use" or contain "unknown filesystem"
	args = append(args, "-f")

	// If mountpoint is not explicitly set, use dedicated storage directory
	mountpoint := options["mountpoint"]
	if mountpoint == "" {
		// Default mountpoint: /storage/pools/{poolname}
		mountpoint = "/storage/pools/" + name
		options["mountpoint"] = mountpoint
	}

	// Pre-create the mountpoint directory with sudo (non-blocking - log errors but continue)
	if mountpoint != "none" {
		if err := s.createMountpointWithSudo(mountpoint); err != nil {
			// Log the error but don't fail - ZFS might still create the pool
			// The mountpoint can be fixed later if needed
			log.Printf("warning: failed to pre-create mountpoint %s: %v (continuing anyway)", mountpoint, err)
		}
	}

	// Set canmount=noauto to prevent automatic mounting during creation
	// This allows pool creation to succeed even if mountpoint can't be created
	if _, hasCanmount := options["canmount"]; !hasCanmount {
		options["canmount"] = "noauto"
	}

	// IMPORTANT: Don't set mountpoint during pool creation
	// ZFS tries to mount immediately during creation, which can fail
	// We'll set mountpoint after pool is created
	mountpointOption := options["mountpoint"]
	delete(options, "mountpoint") // Remove from options temporarily

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

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

	// Create the pool (without mountpoint to avoid mount errors)
	_, err := s.execCommand(s.zpoolPath, args...)

	// CRITICAL: Always check if pool exists, even if creation reported an error
	// ZFS often reports mountpoint errors but pool is still created successfully
	poolExists := false
	if existingPools, listErr := s.ListPools(); listErr == nil {
		for _, pool := range existingPools {
			if pool.Name == name {
				poolExists = true
				break
			}
		}
	}

	if poolExists {
		// Pool exists! This is success, regardless of any reported errors
		if err != nil {
			log.Printf("info: pool %s created successfully despite reported error: %v", name, err)
		}
		// Clear error since pool was created
		err = nil
	} else if err != nil {
		// Pool doesn't exist and we have an error - return it
		return err
	}

	// Pool created successfully - now set mountpoint and mount if needed
	if mountpoint != "none" && mountpointOption != "" && poolExists {
		// Ensure mountpoint directory exists
		if err := s.createMountpointWithSudo(mountpoint); err != nil {
			log.Printf("warning: failed to create mountpoint %s: %v", mountpoint, err)
		}

		// Set mountpoint property on the root filesystem of the pool
		setMountpointArgs := []string{"set", fmt.Sprintf("mountpoint=%s", mountpoint), name}
		if _, setErr := s.execCommand(s.zfsPath, setMountpointArgs...); setErr != nil {
			log.Printf("warning: failed to set mountpoint property: %v (pool created but not mounted)", setErr)
			// Don't return error - pool is created successfully
		} else {
			// Try to mount the pool
			mountArgs := []string{"mount", name}
			if _, mountErr := s.execCommand(s.zfsPath, mountArgs...); mountErr != nil {
				log.Printf("warning: failed to mount pool: %v (pool created but not mounted)", mountErr)
				// Don't return error - pool is created successfully, just not mounted
			}
		}
	}

	return nil
}

// createMountpointWithSudo creates a mountpoint directory using sudo
// This allows ZFS to mount pools even if root filesystem appears read-only
func (s *Service) createMountpointWithSudo(path string) error {
	// Use sudo to create the directory with proper permissions
	cmd := exec.Command("sudo", "-n", "mkdir", "-p", path)
	var stderr bytes.Buffer
	cmd.Stderr = &stderr

	if err := cmd.Run(); err != nil {
		// If sudo mkdir fails, try without sudo (might already be root or have permissions)
		directCmd := exec.Command("mkdir", "-p", path)
		if directErr := directCmd.Run(); directErr != nil {
			// Both failed, but don't return error - ZFS might handle it
			// Log but continue, as ZFS might create it or mountpoint might already exist
			return fmt.Errorf("failed to create mountpoint %s: %v: %s", path, err, stderr.String())
		}
	}
	return nil
}

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

// ImportPool imports a ZFS pool
func (s *Service) ImportPool(name string, options map[string]string) error {
	args := []string{"import"}

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

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

// ExportPool exports a ZFS pool
func (s *Service) ExportPool(name string, force bool) error {
	args := []string{"export"}
	if force {
		args = append(args, "-f")
	}
	args = append(args, name)
	_, err := s.execCommand(s.zpoolPath, args...)
	return err
}

// ListAvailablePools returns pools that can be imported
func (s *Service) ListAvailablePools() ([]string, error) {
	output, err := s.execCommand(s.zpoolPath, "import")
	if err != nil {
		return nil, err
	}

	var pools []string
	lines := strings.Split(output, "\n")
	for _, line := range lines {
		line = strings.TrimSpace(line)
		if line == "" {
			continue
		}
		// Parse pool name from output like "pool: tank"
		if strings.HasPrefix(line, "pool:") {
			parts := strings.Fields(line)
			if len(parts) >= 2 {
				pools = append(pools, parts[1])
			}
		}
	}

	return pools, nil
}

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

// ScrubStatus represents detailed scrub operation status
type ScrubStatus struct {
	Status      string  `json:"status"`       // idle, in_progress, completed, error
	Progress    float64 `json:"progress"`     // 0-100
	TimeElapsed string  `json:"time_elapsed"` // e.g., "2h 15m"
	TimeRemain  string  `json:"time_remain"`  // e.g., "30m"
	Speed       string  `json:"speed"`        // e.g., "100M/s"
	Errors      int     `json:"errors"`       // number of errors found
	Repaired    int     `json:"repaired"`     // number of errors repaired
	LastScrub   string  `json:"last_scrub"`   // timestamp of last completed scrub
}

// GetScrubStatus returns detailed scrub status with progress
func (s *Service) GetScrubStatus(name string) (*ScrubStatus, error) {
	status := &ScrubStatus{
		Status: "idle",
	}

	// Get pool status
	output, err := s.execCommand(s.zpoolPath, "status", name)
	if err != nil {
		return nil, err
	}

	// Parse scrub information
	lines := strings.Split(output, "\n")
	inScrubSection := false
	for _, line := range lines {
		line = strings.TrimSpace(line)

		// Check if scrub is in progress
		if strings.Contains(line, "scrub in progress") {
			status.Status = "in_progress"
			inScrubSection = true
			continue
		}

		// Check if scrub completed
		if strings.Contains(line, "scrub repaired") || strings.Contains(line, "scrub completed") {
			status.Status = "completed"
			status.Progress = 100.0
			// Extract repair information
			if strings.Contains(line, "repaired") {
				// Try to extract number of repairs
				parts := strings.Fields(line)
				for i, part := range parts {
					if part == "repaired" && i > 0 {
						// Previous part might be the number
						if repaired, err := strconv.Atoi(parts[i-1]); err == nil {
							status.Repaired = repaired
						}
					}
				}
			}
			continue
		}

		// Parse progress percentage
		if strings.Contains(line, "%") && inScrubSection {
			// Extract percentage from line like "scan: 45.2% done"
			parts := strings.Fields(line)
			for _, part := range parts {
				if strings.HasSuffix(part, "%") {
					if pct, err := strconv.ParseFloat(strings.TrimSuffix(part, "%"), 64); err == nil {
						status.Progress = pct
					}
				}
			}
		}

		// Parse time elapsed
		if strings.Contains(line, "elapsed") && inScrubSection {
			// Extract time like "elapsed: 2h15m"
			parts := strings.Fields(line)
			for i, part := range parts {
				if part == "elapsed:" && i+1 < len(parts) {
					status.TimeElapsed = parts[i+1]
				}
			}
		}

		// Parse time remaining
		if strings.Contains(line, "remaining") && inScrubSection {
			parts := strings.Fields(line)
			for i, part := range parts {
				if part == "remaining:" && i+1 < len(parts) {
					status.TimeRemain = parts[i+1]
				}
			}
		}

		// Parse speed
		if strings.Contains(line, "scan rate") && inScrubSection {
			parts := strings.Fields(line)
			for i, part := range parts {
				if part == "rate" && i+1 < len(parts) {
					status.Speed = parts[i+1]
				}
			}
		}

		// Parse errors
		if strings.Contains(line, "errors:") && inScrubSection {
			parts := strings.Fields(line)
			for i, part := range parts {
				if part == "errors:" && i+1 < len(parts) {
					if errs, err := strconv.Atoi(parts[i+1]); err == nil {
						status.Errors = errs
					}
				}
			}
		}
	}

	// Get last scrub time from pool properties
	lastScrub, err := s.execCommand(s.zfsPath, "get", "-H", "-o", "value", "lastscrub", name)
	if err == nil && lastScrub != "-" && lastScrub != "" {
		status.LastScrub = strings.TrimSpace(lastScrub)
	}

	return status, 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 empty slice instead of nil to ensure JSON encodes as [] not null
		return []models.Dataset{}, err
	}

	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"}

	if options == nil {
		options = make(map[string]string)
	}

	// If mountpoint is not explicitly set, use dedicated storage directory
	mountpoint := options["mountpoint"]
	if mountpoint == "" {
		// Extract dataset name (last part after /)
		parts := strings.Split(name, "/")
		datasetName := parts[len(parts)-1]
		// Default mountpoint: /storage/datasets/{datasetname}
		mountpoint = "/storage/datasets/" + datasetName
		options["mountpoint"] = mountpoint
		// Pre-create the mountpoint directory with sudo
		_ = s.createMountpointWithSudo(mountpoint)
	} else if mountpoint != "none" {
		// Ensure mountpoint directory exists with sudo
		_ = s.createMountpointWithSudo(mountpoint)
	}

	// Add options
	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 empty slice instead of nil to ensure JSON encodes as [] not null
		return []models.ZVOL{}, err
	}

	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
}

// ListSnapshots returns all snapshots for a dataset (or all if dataset is empty)
func (s *Service) ListSnapshots(dataset string) ([]models.Snapshot, error) {
	args := []string{"list", "-H", "-o", "name,used,creation", "-t", "snapshot", "-s", "creation"}
	if dataset != "" {
		args = append(args, "-r", dataset)
	} else {
		args = append(args, "-r")
	}

	output, err := s.execCommand(s.zfsPath, args...)
	if err != nil {
		// Return empty slice instead of nil to ensure JSON encodes as [] not null
		return []models.Snapshot{}, err
	}

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

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

		fullName := fields[0]
		// Snapshot name format: dataset@snapshot
		parts := strings.Split(fullName, "@")
		if len(parts) != 2 {
			continue
		}

		datasetName := parts[0]

		snapshot := models.Snapshot{
			Name:    fullName,
			Dataset: datasetName,
		}

		// Parse size
		if used, err := parseSize(fields[1]); err == nil {
			snapshot.Size = used
		}

		// Parse creation time
		// ZFS creation format: "Mon Jan 2 15:04:05 2006"
		createdStr := strings.Join(fields[2:], " ")
		if t, err := time.Parse("Mon Jan 2 15:04:05 2006", createdStr); err == nil {
			snapshot.CreatedAt = t
		} else {
			// Try RFC3339 format if available
			if t, err := time.Parse(time.RFC3339, createdStr); err == nil {
				snapshot.CreatedAt = t
			}
		}

		snapshots = append(snapshots, snapshot)
	}

	return snapshots, nil
}

// CreateSnapshot creates a new snapshot
func (s *Service) CreateSnapshot(dataset, name string, recursive bool) error {
	args := []string{"snapshot"}
	if recursive {
		args = append(args, "-r")
	}

	snapshotName := fmt.Sprintf("%s@%s", dataset, name)
	args = append(args, snapshotName)

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

// DestroySnapshot destroys a snapshot
func (s *Service) DestroySnapshot(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
}

// GetSnapshot returns snapshot details
func (s *Service) GetSnapshot(name string) (*models.Snapshot, error) {
	snapshots, err := s.ListSnapshots("")
	if err != nil {
		return nil, err
	}

	for _, snap := range snapshots {
		if snap.Name == name {
			return &snap, nil
		}
	}

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