//go:build linux

package report

import (
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"

	"gitea.dooplex.hu/admin/felhom-controller/internal/backup"
)

// collectDiskLayout reads /host-fstab and correlates with blkid/lsblk to build
// the disk mount topology. Only includes data partitions (not root, boot, or swap).
func collectDiskLayout(systemDataPath string) backup.DiskLayout {
	layout := backup.DiskLayout{}

	fstabPath := "/host-fstab"
	if _, err := os.Stat(fstabPath); err != nil {
		fstabPath = "/etc/fstab"
	}

	data, err := os.ReadFile(fstabPath)
	if err != nil {
		return layout
	}

	// Parse fstab into UUID-based entries and bind mount entries
	type fstabEntry struct {
		source     string
		mountPoint string
		fsType     string
		options    string
	}

	var uuidEntries []fstabEntry
	var bindEntries []fstabEntry

	systemMounts := map[string]bool{"/": true, "/boot": true, "/boot/efi": true}

	for _, line := range strings.Split(string(data), "\n") {
		line = strings.TrimSpace(line)
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		fields := strings.Fields(line)
		if len(fields) < 4 {
			continue
		}
		source := fields[0]
		mountPoint := fields[1]
		fsType := fields[2]
		options := fields[3]

		// Skip system mounts and swap
		if systemMounts[mountPoint] || fsType == "swap" {
			continue
		}

		if strings.HasPrefix(source, "UUID=") {
			uuidEntries = append(uuidEntries, fstabEntry{
				source:     strings.TrimPrefix(source, "UUID="),
				mountPoint: mountPoint,
				fsType:     fsType,
				options:    options,
			})
		} else if fsType == "none" && strings.Contains(options, "bind") {
			bindEntries = append(bindEntries, fstabEntry{
				source:     source,
				mountPoint: mountPoint,
				options:    options,
			})
		}
	}

	// Process UUID-based entries
	for _, e := range uuidEntries {
		dm := backup.DiskMount{
			UUID:         e.source,
			MountPoint:   e.mountPoint,
			FSType:       e.fsType,
			FstabOptions: e.options,
		}

		// Get label via blkid
		if out, err := exec.Command("blkid", "-o", "value", "-s", "LABEL", "-U", e.source).Output(); err == nil {
			dm.Label = strings.TrimSpace(string(out))
		}

		// Get size via lsblk (resolve UUID to device first)
		if devPath, err := exec.Command("blkid", "-U", e.source).Output(); err == nil {
			dev := strings.TrimSpace(string(devPath))
			if dev != "" {
				if out, err := exec.Command("lsblk", "-b", "-n", "-o", "SIZE", dev).Output(); err == nil {
					if sz, err := strconv.ParseInt(strings.TrimSpace(string(out)), 10, 64); err == nil {
						dm.SizeBytes = sz
					}
				}
			}
		}

		// Determine role
		if e.mountPoint == systemDataPath {
			dm.Role = "system_data"
		} else {
			dm.Role = "hdd_storage"
		}

		// Check for a corresponding bind mount
		for _, bind := range bindEntries {
			if strings.HasPrefix(bind.source, e.mountPoint+"/") {
				subdir := strings.TrimPrefix(bind.source, e.mountPoint+"/")
				dm.BindSubdir = subdir
				dm.RawMount = e.mountPoint
				dm.MountPoint = bind.mountPoint // the final user-facing mount point
				break
			}
		}

		// Get label from mount point basename as fallback
		if dm.Label == "" {
			if dm.RawMount != "" {
				dm.Label = filepath.Base(dm.RawMount)
			} else {
				dm.Label = filepath.Base(dm.MountPoint)
			}
		}

		layout.Mounts = append(layout.Mounts, dm)
	}

	return layout
}