package device

import (
	"context"
	"fmt"

	"github.com/google/gousb"
)

// Info describes a USB device for the diagnostics listing.
type Info struct {
	VendorID     int
	ProductID    int
	Manufacturer string
	Product      string
	Serial       string
	Bus          int
	Address      int
	IsLCD        bool
}

// ListDevices enumerates all USB devices visible to libusb. Descriptor
// strings are best-effort: reading them requires device access, which is
// why failures are ignored.
func ListDevices(ctx context.Context) ([]Info, error) {
	gctx := gousb.NewContext()
	defer gctx.Close()

	devs, err := gctx.OpenDevices(func(*gousb.DeviceDesc) bool { return true })
	if err != nil && len(devs) == 0 {
		return nil, fmt.Errorf("enumerate USB devices (run as root or install the udev rule): %w", err)
	}
	defer func() {
		for _, d := range devs {
			_ = d.Close()
		}
	}()

	infos := make([]Info, 0, len(devs))
	for _, d := range devs {
		info := Info{
			VendorID:  int(d.Desc.Vendor),
			ProductID: int(d.Desc.Product),
			Bus:       d.Desc.Bus,
			Address:   d.Desc.Address,
			IsLCD:     d.Desc.Vendor == gousb.ID(0x0416) && d.Desc.Product == gousb.ID(0x7395),
		}
		if info.IsLCD {
			// Only read strings for the device we care about.
			info.Manufacturer, _ = d.Manufacturer()
			info.Product, _ = d.Product()
			info.Serial, _ = d.SerialNumber()
		}
		infos = append(infos, info)
	}
	return infos, err
}