package device

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"

	"github.com/wobkey/rgb/internal/hid"
)

// Keyboard represents a VIA-compatible keyboard from keyboards.json.
type Keyboard struct {
	Name       string `json:"name"`
	VendorID   uint16 `json:"vendorId"`
	ProductID  uint16 `json:"productId"`
	Protocol   string `json:"protocol"`
	VIAVersion int    `json:"viaVersion"`
	LEDLayout  string `json:"ledLayout"`
}

// Device represents a connected keyboard device.
type Device struct {
	Keyboard
	Path string
}

// LoadKeyboards reads keyboard definitions from keyboards.json.
func LoadKeyboards() ([]Keyboard, error) {
	path, err := findKeyboardsJSON()
	if err != nil {
		return nil, fmt.Errorf("find keyboards.json: %w", err)
	}

	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read keyboards.json: %w", err)
	}

	var keyboards []Keyboard
	if err := json.Unmarshal(data, &keyboards); err != nil {
		return nil, fmt.Errorf("parse keyboards.json: %w", err)
	}

	return keyboards, nil
}

// findKeyboardsJSON searches for keyboards.json in common locations.
var findKeyboardsJSON = func() (string, error) {
	exe, err := os.Executable()
	if err == nil {
		path := filepath.Join(filepath.Dir(exe), "keyboards.json")
		if _, err := os.Stat(path); err == nil {
			return path, nil
		}
	}

	path := "keyboards.json"
	if _, err := os.Stat(path); err == nil {
		return path, nil
	}

	cwd, err := os.Getwd()
	if err == nil {
		path := filepath.Join(cwd, "keyboards.json")
		if _, err := os.Stat(path); err == nil {
			return path, nil
		}
	}

	return "", fmt.Errorf("keyboards.json not found")
}

// Discover scans for connected VIA-compatible keyboards.
func Discover(keyboards []Keyboard) ([]Device, error) {
	var found []Device
	for _, kb := range keyboards {
		err := hid.Enumerate(kb.VendorID, kb.ProductID, func(info *hid.DeviceInfo) error {
			found = append(found, Device{
				Keyboard: kb,
				Path:     info.Path,
			})
			return nil
		})
		if err != nil {
			return nil, fmt.Errorf("enumerate VID=0x%04x PID=0x%04x: %w", kb.VendorID, kb.ProductID, err)
		}
	}

	fmt.Fprintf(os.Stderr, "DEBUG discover: found %d keyboard(s)\n", len(found))
	for _, d := range found {
		fmt.Fprintf(os.Stderr, "DEBUG discover:   %s path=%s VID=0x%04x PID=0x%04x\n", d.Name, d.Path, d.VendorID, d.ProductID)
	}

	return found, nil
}