package platform

import (
	"context"
	"fmt"
	"os/exec"
	"strconv"
	"strings"
)

// InstallDisk describes a candidate disk for installation.
type InstallDisk struct {
	Device string // e.g. /dev/sda
	Model  string
	Size   string // human-readable, e.g. "500G"
}

// ListInstallDisks returns block devices suitable for installation.
// Excludes USB drives and the current live boot medium.
func (s *System) ListInstallDisks() ([]InstallDisk, error) {
	out, err := exec.Command("lsblk", "-dn", "-o", "NAME,MODEL,SIZE,TYPE,TRAN").Output()
	if err != nil {
		return nil, fmt.Errorf("lsblk: %w", err)
	}

	bootDev := findLiveBootDevice()

	var disks []InstallDisk
	for _, line := range strings.Split(strings.TrimSpace(string(out)), "\n") {
		fields := strings.Fields(line)
		// NAME MODEL SIZE TYPE TRAN  — model may have spaces so we parse from end
		if len(fields) < 4 {
			continue
		}
		// Last field: TRAN, second-to-last: TYPE, third-to-last: SIZE
		tran := fields[len(fields)-1]
		typ := fields[len(fields)-2]
		size := fields[len(fields)-3]
		name := fields[0]
		model := strings.Join(fields[1:len(fields)-3], " ")

		if typ != "disk" {
			continue
		}
		if strings.EqualFold(tran, "usb") {
			continue
		}

		device := "/dev/" + name
		if device == bootDev {
			continue
		}

		disks = append(disks, InstallDisk{
			Device: device,
			Model:  strings.TrimSpace(model),
			Size:   size,
		})
	}
	return disks, nil
}

// findLiveBootDevice returns the block device backing /run/live/medium (if any).
func findLiveBootDevice() string {
	out, err := exec.Command("findmnt", "-n", "-o", "SOURCE", "/run/live/medium").Output()
	if err != nil {
		return ""
	}
	src := strings.TrimSpace(string(out))
	if src == "" {
		return ""
	}
	// Strip partition suffix to get the whole disk device.
	// e.g. /dev/sdb1 → /dev/sdb,  /dev/nvme0n1p1 → /dev/nvme0n1
	out2, err := exec.Command("lsblk", "-no", "PKNAME", src).Output()
	if err != nil || strings.TrimSpace(string(out2)) == "" {
		return src
	}
	return "/dev/" + strings.TrimSpace(string(out2))
}

// InstallToDisk runs bee-install <device> <logfile> and streams output to logFile.
// The context can be used to cancel.
func (s *System) InstallToDisk(ctx context.Context, device string, logFile string) error {
	cmd := exec.CommandContext(ctx, "bee-install", device, logFile)
	return cmd.Run()
}

// InstallLogPath returns the default install log path for a given device.
func InstallLogPath(device string) string {
	safe := strings.NewReplacer("/", "_", " ", "_").Replace(device)
	return "/tmp/bee-install" + safe + ".log"
}

// DiskLabel returns a display label for a disk.
func (d InstallDisk) Label() string {
	model := d.Model
	if model == "" {
		model = "Unknown"
	}
	sizeBytes, err := strconv.ParseInt(strings.TrimSuffix(d.Size, "B"), 10, 64)
	_ = sizeBytes
	_ = err
	return fmt.Sprintf("%s  %s  %s", d.Device, d.Size, model)
}