package deployer

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"runtime"
	"strings"

	"nexusrmm.local/agent/internal/executor"
)

// Payload wird vom Backend als JSON im cmd.Payload-Feld gesendet.
type Payload struct {
	PackageName    string `json:"packageName"`
	PackageManager string `json:"packageManager"` // "choco", "apt", "dnf", "direct"
	InstallerUrl   string `json:"installerUrl"`
	Checksum       string `json:"checksum"`     // SHA256 (hex, optional)
	SilentArgs     string `json:"silentArgs"`
	DisplayName    string `json:"displayName"`
	Version        string `json:"version"`
}

// Install installiert ein Software-Paket auf dem aktuellen System.
func Install(ctx context.Context, payloadJSON string) *executor.Result {
	payload, err := parsePayload(payloadJSON)
	if err != nil {
		return errorResult(fmt.Sprintf("Ungültiges Payload-JSON: %v", err))
	}

	switch payload.PackageManager {
	case "choco":
		return installWithChoco(ctx, payload.PackageName)
	case "apt":
		return installWithApt(ctx, payload.PackageName)
	case "dnf":
		return installWithDnf(ctx, payload.PackageName)
	case "direct":
		return installDirect(ctx, *payload)
	default:
		// Auto-detect
		return installAutoDetect(ctx, *payload)
	}
}

// Uninstall deinstalliert ein Software-Paket.
func Uninstall(ctx context.Context, payloadJSON string) *executor.Result {
	payload, err := parsePayload(payloadJSON)
	if err != nil {
		return errorResult(fmt.Sprintf("Ungültiges Payload-JSON: %v", err))
	}

	switch payload.PackageManager {
	case "choco":
		return executor.Execute(ctx, fmt.Sprintf("choco uninstall %s -y", payload.PackageName), 600)
	case "apt":
		return executor.Execute(ctx, fmt.Sprintf("apt-get remove -y %s", payload.PackageName), 600)
	case "dnf":
		return executor.Execute(ctx, fmt.Sprintf("dnf remove -y %s", payload.PackageName), 600)
	default:
		return installAutoDetect(ctx, *payload)
	}
}

func installWithChoco(ctx context.Context, packageName string) *executor.Result {
	return executor.Execute(ctx,
		fmt.Sprintf("choco install %s -y --no-progress", packageName), 600)
}

func installWithApt(ctx context.Context, packageName string) *executor.Result {
	return executor.Execute(ctx,
		fmt.Sprintf("DEBIAN_FRONTEND=noninteractive apt-get install -y %s", packageName), 600)
}

func installWithDnf(ctx context.Context, packageName string) *executor.Result {
	return executor.Execute(ctx,
		fmt.Sprintf("dnf install -y %s", packageName), 600)
}

func installAutoDetect(ctx context.Context, payload Payload) *executor.Result {
	if runtime.GOOS == "windows" {
		// Versuche choco, dann winget als Fallback
		if isCommandAvailable("choco") {
			return installWithChoco(ctx, payload.PackageName)
		}
		if payload.InstallerUrl != "" {
			return installDirect(ctx, payload)
		}
		return errorResult("Kein unterstützter Paketmanager auf Windows verfügbar (choco nicht gefunden)")
	}
	// Linux
	if isCommandAvailable("apt-get") {
		return installWithApt(ctx, payload.PackageName)
	}
	if isCommandAvailable("dnf") {
		return installWithDnf(ctx, payload.PackageName)
	}
	if payload.InstallerUrl != "" {
		return installDirect(ctx, payload)
	}
	return errorResult("Kein unterstützter Paketmanager auf Linux verfügbar")
}

func installDirect(ctx context.Context, payload Payload) *executor.Result {
	if payload.InstallerUrl == "" {
		return errorResult("Direct-Install: Keine InstallerUrl angegeben")
	}

	// Temp-Datei herunterladen
	tmpFile, err := os.CreateTemp("", "nexusrmm-install-*")
	if err != nil {
		return errorResult(fmt.Sprintf("Temp-Datei konnte nicht erstellt werden: %v", err))
	}
	tmpPath := tmpFile.Name()
	defer os.Remove(tmpPath)

	resp, err := http.Get(payload.InstallerUrl)
	if err != nil {
		tmpFile.Close()
		return errorResult(fmt.Sprintf("Download fehlgeschlagen: %v", err))
	}
	defer resp.Body.Close()

	hasher := sha256.New()
	writer := io.MultiWriter(tmpFile, hasher)
	if _, err := io.Copy(writer, resp.Body); err != nil {
		tmpFile.Close()
		return errorResult(fmt.Sprintf("Download-Fehler beim Schreiben: %v", err))
	}
	tmpFile.Close()

	// Checksum prüfen
	if payload.Checksum != "" {
		actualHash := hex.EncodeToString(hasher.Sum(nil))
		expected := strings.ToLower(payload.Checksum)
		if actualHash != expected {
			return errorResult(fmt.Sprintf("Prüfsummen-Fehler: erwartet %s, erhalten %s", expected, actualHash))
		}
	}

	// Installer ausführen
	ext := strings.ToLower(filepath.Ext(payload.InstallerUrl))
	var installCmd string
	switch {
	case runtime.GOOS == "windows" && ext == ".msi":
		installCmd = fmt.Sprintf("msiexec /i \"%s\" /quiet /norestart %s", tmpPath, payload.SilentArgs)
	case runtime.GOOS == "windows" && (ext == ".exe"):
		installCmd = fmt.Sprintf("\"%s\" %s", tmpPath, payload.SilentArgs)
	case runtime.GOOS == "linux" && (ext == ".deb"):
		installCmd = fmt.Sprintf("dpkg -i \"%s\"", tmpPath)
	case runtime.GOOS == "linux" && (ext == ".rpm"):
		installCmd = fmt.Sprintf("rpm -i \"%s\"", tmpPath)
	default:
		installCmd = fmt.Sprintf("\"%s\" %s", tmpPath, payload.SilentArgs)
	}

	return executor.Execute(ctx, installCmd, 1200)
}

func isCommandAvailable(name string) bool {
	result := executor.Execute(context.Background(), "which "+name+" || where "+name, 5)
	return result.Success || result.ExitCode == 0
}

func parsePayload(payloadJSON string) (*Payload, error) {
	var p Payload
	if err := json.Unmarshal([]byte(payloadJSON), &p); err != nil {
		return nil, err
	}
	return &p, nil
}

func errorResult(msg string) *executor.Result {
	return &executor.Result{
		ExitCode: -1,
		Stderr:   msg,
		Success:  false,
	}
}