package kneron

import (
	"encoding/json"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"

	"visiona-local/server/internal/driver"
)

// ResolvePython finds the best Python interpreter for the given script path.
// Search order: script-local venv → parent venv → platform config dir venv → system python3/python.
func ResolvePython(scriptPath string) string {
	scriptDir := filepath.Dir(scriptPath)
	parentDir := filepath.Dir(scriptDir)

	// Build candidate list with both Unix and Windows venv layouts
	var candidates []string
	for _, base := range []string{scriptDir, parentDir} {
		candidates = append(candidates,
			filepath.Join(base, "venv", "bin", "python3"),           // Unix
			filepath.Join(base, "venv", "Scripts", "python.exe"),    // Windows
		)
	}

	if home, err := os.UserHomeDir(); err == nil {
		candidates = append(candidates,
			filepath.Join(home, ".edge-ai-platform", "venv", "bin", "python3"),
			filepath.Join(home, ".edge-ai-platform", "venv", "Scripts", "python.exe"),
		)
	}

	// On Windows, also check %LOCALAPPDATA%\EdgeAIPlatform\venv
	if appData := os.Getenv("LOCALAPPDATA"); appData != "" {
		candidates = append(candidates,
			filepath.Join(appData, "EdgeAIPlatform", "venv", "Scripts", "python.exe"),
		)
	}

	for _, p := range candidates {
		if _, err := os.Stat(p); err == nil {
			return p
		}
	}

	// Fallback to system python
	for _, name := range []string{"python3", "python"} {
		if p, err := exec.LookPath(name); err == nil {
			return p
		}
	}

	return "python3"
}

// KneronVendorID is the USB vendor ID for Kneron devices.
const KneronVendorID uint16 = 0x3231

// Known Kneron product IDs.
const (
	ProductIDKL520 = "0x0100"
	ProductIDKL720 = "0x0200"
	ProductIDKL720Alt = "0x0720"
)

// chipFromProductID returns the chip name and device type from the product_id
// reported by the Python bridge scan result.
func chipFromProductID(productID string) (chip string, deviceType string) {
	pid := strings.ToLower(strings.TrimSpace(productID))
	switch pid {
	case "0x0100":
		return "KL520", "kneron_kl520"
	case "0x0200", "0x0720":
		return "KL720", "kneron_kl720"
	default:
		// Unknown product — default to KL520 for USB Boot devices,
		// otherwise use the raw product ID as suffix.
		return "KL520", "kneron_kl520"
	}
}

// DetectDevices attempts to discover all connected Kneron devices (KL520, KL720, etc.)
// by invoking the Python bridge script with a scan command. If Python or
// the bridge script is not available, it returns an empty list.
func DetectDevices(scriptPath string) []driver.DeviceInfo {
	// Try to run the bridge script with a scan command via a short-lived process.
	pythonBin := ResolvePython(scriptPath)
	cmd := exec.Command(pythonBin, scriptPath)
	cmd.Stdin = nil

	// Ensure libusb-1.0.dll can be found on Windows by adding the binary's
	// directory to PATH (the installer places the DLL there).
	scriptDir := filepath.Dir(scriptPath)
	installDir := filepath.Dir(scriptDir)
	cmd.Env = append(os.Environ(),
		fmt.Sprintf("PATH=%s;%s;%s", installDir, scriptDir, os.Getenv("PATH")),
	)

	stdinPipe, err := cmd.StdinPipe()
	if err != nil {
		return nil
	}

	stdoutPipe, err := cmd.StdoutPipe()
	if err != nil {
		stdinPipe.Close()
		return nil
	}

	if err := cmd.Start(); err != nil {
		return nil
	}

	defer func() {
		stdinPipe.Close()
		cmd.Process.Kill()
		cmd.Wait()
	}()

	// Read the ready signal.
	decoder := json.NewDecoder(stdoutPipe)
	var readyResp map[string]interface{}
	done := make(chan error, 1)
	go func() {
		done <- decoder.Decode(&readyResp)
	}()

	select {
	case err := <-done:
		if err != nil {
			return nil
		}
	case <-time.After(5 * time.Second):
		return nil
	}

	if status, ok := readyResp["status"].(string); !ok || status != "ready" {
		return nil
	}

	// Send the scan command.
	scanCmd, _ := json.Marshal(map[string]interface{}{"cmd": "scan"})
	scanCmd = append(scanCmd, '\n')
	if _, err := stdinPipe.Write(scanCmd); err != nil {
		return nil
	}

	// Read the scan response.
	var scanResp map[string]interface{}
	scanDone := make(chan error, 1)
	go func() {
		scanDone <- decoder.Decode(&scanResp)
	}()

	select {
	case err := <-scanDone:
		if err != nil {
			return nil
		}
	case <-time.After(5 * time.Second):
		return nil
	}

	// Parse detected devices from the response.
	devicesRaw, ok := scanResp["devices"].([]interface{})
	if !ok || len(devicesRaw) == 0 {
		return nil
	}

	// Track per-chip counters for naming (e.g. "KL520 #1", "KL720 #1").
	chipCount := map[string]int{}

	var devices []driver.DeviceInfo
	for _, devRaw := range devicesRaw {
		dev, ok := devRaw.(map[string]interface{})
		if !ok {
			continue
		}

		port := ""
		if p, ok := dev["port"].(string); ok {
			port = p
		}

		fw := ""
		if f, ok := dev["firmware"].(string); ok {
			fw = f
		}

		productID := ""
		if p, ok := dev["product_id"].(string); ok {
			productID = p
		}

		chip, devType := chipFromProductID(productID)
		chipCount[chip]++
		idx := chipCount[chip]

		info := driver.DeviceInfo{
			ID:          fmt.Sprintf("%s-%d", strings.ToLower(chip), idx-1),
			Name:        fmt.Sprintf("Kneron %s #%d", chip, idx),
			Type:        devType,
			Port:        port,
			VendorID:    KneronVendorID,
			Status:      driver.StatusDetected,
			FirmwareVer: fw,
		}
		devices = append(devices, info)
	}

	return devices
}

// DetectKL720Devices is a backward-compatible alias for DetectDevices.
// Deprecated: Use DetectDevices instead.
func DetectKL720Devices(scriptPath string) []driver.DeviceInfo {
	return DetectDevices(scriptPath)
}