package runner

import (
	"context"
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"

	"github.com/j3ssie/osmedeus/v5/internal/core"
	"github.com/pkg/sftp"
	"golang.org/x/crypto/ssh"
)

// SSHRunner executes commands on a remote machine via SSH
type SSHRunner struct {
	config     *core.RunnerConfig
	binaryPath string
	client     *ssh.Client
	remoteDir  string
	pooled     bool       // true if connection is from pool
	poolKey    SSHPoolKey // key for releasing back to pool
}

// NewSSHRunner creates a new SSH runner
func NewSSHRunner(config *core.RunnerConfig, binaryPath string) (*SSHRunner, error) {
	if config.Host == "" {
		return nil, fmt.Errorf("SSH runner requires host to be specified")
	}
	if config.User == "" {
		return nil, fmt.Errorf("SSH runner requires user to be specified")
	}

	return &SSHRunner{
		config:     config,
		binaryPath: binaryPath,
		remoteDir:  "~/.osmedeus-remote",
	}, nil
}

// Setup establishes SSH connection and copies the binary
// Uses connection pooling to reuse SSH connections across steps
func (r *SSHRunner) Setup(ctx context.Context) error {
	// Get connection from pool
	pool := GetSSHPool()
	client, poolKey, err := pool.Get(ctx, r.config)
	if err != nil {
		return err
	}

	r.client = client
	r.pooled = true
	r.poolKey = poolKey

	// Create remote directory
	if _, err := r.runCommand(ctx, "mkdir -p "+r.remoteDir); err != nil {
		return fmt.Errorf("failed to create remote directory: %w", err)
	}

	// Copy binary to remote machine if it exists
	if r.binaryPath != "" {
		if err := r.copyBinary(); err != nil {
			// Non-fatal, log and continue
			fmt.Printf("Warning: failed to copy binary to remote: %v\n", err)
		}
	}

	return nil
}

// expandPath expands ~ to home directory
func (r *SSHRunner) expandPath(path string) string {
	if strings.HasPrefix(path, "~/") {
		home, err := os.UserHomeDir()
		if err == nil {
			return filepath.Join(home, path[2:])
		}
	}
	return path
}

// copyBinary copies the osmedeus binary to the remote machine using SFTP
func (r *SSHRunner) copyBinary() error {
	if r.client == nil {
		return fmt.Errorf("SSH client not connected")
	}

	// Create SFTP client
	sftpClient, err := sftp.NewClient(r.client)
	if err != nil {
		return fmt.Errorf("failed to create SFTP client: %w", err)
	}
	defer func() { _ = sftpClient.Close() }()

	// Expand remote directory
	homeDir, err := r.getRemoteHome()
	if err != nil {
		return fmt.Errorf("failed to get remote home: %w", err)
	}
	remotePath := strings.Replace(r.remoteDir, "~", homeDir, 1)

	// Create remote directory
	_ = sftpClient.MkdirAll(remotePath)

	// Open local file
	localFile, err := os.Open(r.binaryPath)
	if err != nil {
		return fmt.Errorf("failed to open local binary: %w", err)
	}
	defer func() { _ = localFile.Close() }()

	// Get local file info for size
	localInfo, err := localFile.Stat()
	if err != nil {
		return fmt.Errorf("failed to stat local binary: %w", err)
	}

	// Create remote file
	destPath := filepath.Join(remotePath, "osmedeus")
	remoteFile, err := sftpClient.Create(destPath)
	if err != nil {
		return fmt.Errorf("failed to create remote file: %w", err)
	}
	defer func() { _ = remoteFile.Close() }()

	// Copy file
	_, err = io.Copy(remoteFile, localFile)
	if err != nil {
		return fmt.Errorf("failed to copy binary: %w", err)
	}

	// Make executable
	if err := sftpClient.Chmod(destPath, 0755); err != nil {
		return fmt.Errorf("failed to chmod binary: %w", err)
	}

	fmt.Printf("Copied binary to remote (%d bytes)\n", localInfo.Size())
	return nil
}

// getRemoteHome gets the home directory on the remote machine
func (r *SSHRunner) getRemoteHome() (string, error) {
	// Use background context for internal utility calls
	output, err := r.runCommand(context.Background(), "echo $HOME")
	if err != nil {
		return "", err
	}
	return strings.TrimSpace(output), nil
}

// runCommand executes a command on the remote machine with context support
func (r *SSHRunner) runCommand(ctx context.Context, command string) (string, error) {
	if r.client == nil {
		return "", fmt.Errorf("SSH client not connected")
	}

	session, err := r.client.NewSession()
	if err != nil {
		return "", fmt.Errorf("failed to create SSH session: %w", err)
	}
	defer func() { _ = session.Close() }()

	// Set working directory if specified
	if r.config.WorkDir != "" {
		command = fmt.Sprintf("cd %s && %s", r.config.WorkDir, command)
	}

	// Enforce context deadline using timeout command on remote host
	if deadline, ok := ctx.Deadline(); ok {
		remaining := time.Until(deadline)
		if remaining > 0 {
			secs := int(remaining.Seconds())
			if secs > 0 {
				command = fmt.Sprintf("timeout %ds %s", secs, command)
			}
		}
	}

	output, err := session.CombinedOutput(command)
	return string(output), err
}

// Execute runs a command on the remote machine
func (r *SSHRunner) Execute(ctx context.Context, command string) (*CommandResult, error) {
	output, err := r.runCommand(ctx, command)

	exitCode := 0
	if err != nil {
		if exitErr, ok := err.(*ssh.ExitError); ok {
			exitCode = exitErr.ExitStatus()
		}
	}

	return &CommandResult{
		Output:   output,
		ExitCode: exitCode,
		Error:    err,
	}, nil
}

// Cleanup releases the SSH connection back to the pool
func (r *SSHRunner) Cleanup(ctx context.Context) error {
	if r.client != nil {
		if r.pooled {
			// Release back to pool for reuse
			GetSSHPool().Release(r.poolKey)
		} else {
			// Direct close for non-pooled connections
			_ = r.client.Close()
		}
		r.client = nil
	}
	return nil
}

// getPort returns the SSH port, defaulting to 22
func (r *SSHRunner) getPort() int {
	if r.config.Port == 0 {
		return 22
	}
	return r.config.Port
}

// CopyFromRemote copies a file from the SSH host to local using rsync
func (r *SSHRunner) CopyFromRemote(ctx context.Context, remotePath, localPath string) error {
	// Ensure parent directory exists
	if dir := filepath.Dir(localPath); dir != "" && dir != "." {
		if err := os.MkdirAll(dir, 0755); err != nil {
			return fmt.Errorf("failed to create directory: %w", err)
		}
	}

	// Build rsync source: user@host:path
	source := fmt.Sprintf("%s@%s:%s", r.config.User, r.config.Host, remotePath)

	// Build rsync command with SSH options
	args := []string{"-avz", "-e"}
	if r.config.KeyFile != "" {
		keyPath := r.expandPath(r.config.KeyFile)
		args = append(args, fmt.Sprintf("ssh -i %s -p %d -o StrictHostKeyChecking=no", keyPath, r.getPort()))
	} else {
		args = append(args, fmt.Sprintf("ssh -p %d -o StrictHostKeyChecking=no", r.getPort()))
	}
	args = append(args, source, localPath)

	cmd := exec.CommandContext(ctx, "rsync", args...)
	output, err := cmd.CombinedOutput()
	if err != nil {
		return fmt.Errorf("rsync failed: %w, output: %s", err, string(output))
	}
	return nil
}

// Type returns the runner type
func (r *SSHRunner) Type() core.RunnerType {
	return core.RunnerTypeSSH
}

// IsRemote returns true since SSH runner runs on a remote machine
func (r *SSHRunner) IsRemote() bool {
	return true
}

// GetRemoteDir returns the remote directory where binary is stored
func (r *SSHRunner) GetRemoteDir() string {
	return r.remoteDir
}