package daemon

import (
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"syscall"
)

// GetLogFilePath returns the log file path for a given config file
func GetLogFilePath(configPath string) (string, error) {
	logDir, err := getLogDir()
	if err != nil {
		return "", err
	}

	absConfigPath, err := filepath.Abs(configPath)
	if err != nil {
		return "", fmt.Errorf("failed to get absolute config path: %w", err)
	}

	basename := filepath.Base(configPath)
	name := filepath.Base(filepath.Dir(absConfigPath)) + "_" + basename
	return filepath.Join(logDir, name+".log"), nil
}

// Daemonize spawns the process as a daemon and returns
func Daemonize(configPath string) error {
	// Get absolute path to the current executable
	executable, err := os.Executable()
	if err != nil {
		return fmt.Errorf("failed to get executable path: %w", err)
	}

	// Get absolute path to config
	absConfigPath, err := filepath.Abs(configPath)
	if err != nil {
		return fmt.Errorf("failed to get absolute config path: %w", err)
	}

	// Check if already running
	_, running, err := ReadPID(configPath)
	if err != nil {
		return fmt.Errorf("failed to check if instance is running: %w", err)
	}
	if running {
		return fmt.Errorf("instance is already running")
	}

	// Spawn the process in background with --daemon flag
	cmd := exec.Command(executable, "--daemon", absConfigPath)
	cmd.SysProcAttr = &syscall.SysProcAttr{
		Setsid: true, // Create new session
	}

	// Redirect stdout/stderr to log file
	logDir, err := getLogDir()
	if err != nil {
		return fmt.Errorf("failed to get log directory: %w", err)
	}
	if err := os.MkdirAll(logDir, 0755); err != nil {
		return fmt.Errorf("failed to create log directory: %w", err)
	}

	basename := filepath.Base(configPath)
	name := filepath.Base(filepath.Dir(absConfigPath)) + "_" + basename
	logFile := filepath.Join(logDir, name+".log")

	f, err := os.OpenFile(logFile, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
	if err != nil {
		return fmt.Errorf("failed to open log file: %w", err)
	}
	defer f.Close()

	cmd.Stdout = f
	cmd.Stderr = f

	if err := cmd.Start(); err != nil {
		return fmt.Errorf("failed to start daemon: %w", err)
	}

	fmt.Printf("Started KVS instance '%s' (PID will be written by daemon)\n", filepath.Base(configPath))
	fmt.Printf("Logs: %s\n", logFile)

	return nil
}