package guard

import (
	"errors"
	"fmt"
	"strconv"
	"strings"
)

type Status string

const (
	Allowed  Status = "allow"
	Blocked  Status = "block"
	Rejected Status = "reject"
)

type Device struct {
	ID        int
	Name      string
	Status    Status
	VidPid    string
	Permanent bool
}

func (d Device) Title() string       { return d.Name }
func (d Device) Description() string { return fmt.Sprintf("id:%-3d  %s", d.ID, d.VidPid) }
func (d Device) FilterValue() string { return d.Name + " " + d.VidPid }

// parseLine parses a line from "usbguard list-devices":
// 1: allow id 04b3:301b serial "" name "USB Hub" hash "..." via-port "usb1"
func parseLine(line string) (Device, error) {
	colonIdx := strings.Index(line, ":")
	if colonIdx < 0 {
		return Device{}, errors.New("invalid format")
	}

	id, err := strconv.Atoi(strings.TrimSpace(line[:colonIdx]))
	if err != nil {
		return Device{}, err
	}

	rest := strings.TrimSpace(line[colonIdx+1:])
	parts := strings.Fields(rest)
	if len(parts) < 1 {
		return Device{}, errors.New("missing status")
	}

	status := Status(parts[0])
	name := extractField(rest, "name")
	if name == "" {
		name = fmt.Sprintf("Unknown Device #%d", id)
	}

	return Device{
		ID:     id,
		Name:   name,
		Status: status,
		VidPid: extractUnquoted(rest, "id"),
	}, nil
}

func extractField(rule, field string) string {
	prefix := field + ` "`
	idx := strings.Index(rule, prefix)
	if idx < 0 {
		return ""
	}
	rest := rule[idx+len(prefix):]
	end := strings.Index(rest, `"`)
	if end < 0 {
		return ""
	}
	return rest[:end]
}

func extractUnquoted(rule, field string) string {
	prefix := field + " "
	idx := strings.Index(rule, prefix)
	if idx < 0 {
		return ""
	}
	rest := rule[idx+len(prefix):]
	end := strings.IndexAny(rest, " \t\n")
	if end < 0 {
		return rest
	}
	return rest[:end]
}