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 all HID devices and returns connected VIA-compatible keyboards.
func Discover(keyboards []Keyboard) ([]Device, error) {
	devices, err := hid.DiscoverAll()
	if err != nil {
		return nil, fmt.Errorf("enumerate HID devices: %w", err)
	}

	fmt.Fprintf(os.Stderr, "DEBUG discover: keyboards=%d, hid_devices=%d\n", len(keyboards), len(devices))
	for _, kb := range keyboards {
		fmt.Fprintf(os.Stderr, "DEBUG discover:   kb=%s VID=%d PID=%d\n", kb.Name, kb.VendorID, kb.ProductID)
	}
	for _, d := range devices {
		fmt.Fprintf(os.Stderr, "DEBUG discover:   hid=%s VID=%d PID=%d raw=%t\n", d.Path, d.VendorID, d.ProductID, d.RawHID)
	}

	return matchKeyboards(keyboards, devices), nil
}

func matchKeyboards(keyboards []Keyboard, devices []hid.DeviceInfo) []Device {
	var found []Device
	for _, kb := range keyboards {
		for _, d := range devices {
			if !d.RawHID || d.VendorID != kb.VendorID || d.ProductID != kb.ProductID {
				continue
			}
			fmt.Fprintf(os.Stderr, "DEBUG discover: MATCH %s %s rawHID=true\n", kb.Name, d.Path)
			found = append(found, Device{
				Keyboard: kb,
				Path:     d.Path,
			})
		}
	}

	fmt.Fprintf(os.Stderr, "DEBUG discover: found=%d\n", len(found))
	return found
}