package executor

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

	"RYP/backend/compiler/models"
	"RYP/backend/compiler/sandbox"
)

const (
	defaultPythonImage = "python-runner:latest"
	defaultCppImage    = "cpp-runner:latest"
	defaultJavaImage   = "java-runner:latest"
)

// Execute runs the code in the specified language using Docker sandboxing.
func Execute(req models.RunRequest) (*models.ExecutionResult, error) {
	// Create temporary directory for this execution
	tmpDir, err := os.MkdirTemp("", "ryp_sandbox_*")
	if err != nil {
		return nil, fmt.Errorf("failed to create temp directory: %w", err)
	}
	// Defer cleanup of the temporary directory
	defer os.RemoveAll(tmpDir)

	containerDir := "/sandbox"
	ctx := context.Background()

	var result *sandbox.ExecutionResult
	var execErr error

	switch normalizeLanguage(req.Language) {
	case "python":
		// Write python code to main.py
		scriptPath := filepath.Join(tmpDir, "main.py")
		if err := os.WriteFile(scriptPath, []byte(req.Code), 0644); err != nil {
			return nil, fmt.Errorf("failed to write python file: %w", err)
		}

		result, execErr = sandbox.RunWithDocker(
			ctx,
			runnerImage("RYP_PYTHON_IMAGE", defaultPythonImage),
			tmpDir,
			containerDir,
			3*time.Second,
			[]string{"python", "main.py"},
			req.CustomInput,
		)

	case "cpp":
		// Write C++ code to main.cpp
		srcPath := filepath.Join(tmpDir, "main.cpp")
		if err := os.WriteFile(srcPath, []byte(req.Code), 0644); err != nil {
			return nil, fmt.Errorf("failed to write cpp file: %w", err)
		}

		// Compile
		compResult, err := sandbox.RunWithDocker(
			ctx,
			runnerImage("RYP_CPP_IMAGE", defaultCppImage),
			tmpDir,
			containerDir,
			5*time.Second,
			[]string{"g++", "main.cpp", "-o", "main"},
			"",
		)
		if err != nil {
			return nil, fmt.Errorf("compile error: %w", err)
		}
		if compResult.ExitCode != 0 {
			// Compilation failed
			return &models.ExecutionResult{
				Stdout:     compResult.Stdout,
				Stderr:     compResult.Stderr,
				ExitCode:   compResult.ExitCode,
				DurationMs: compResult.DurationMs,
			}, nil
		}

		// Execute
		result, execErr = sandbox.RunWithDocker(
			ctx,
			runnerImage("RYP_CPP_IMAGE", defaultCppImage),
			tmpDir,
			containerDir,
			3*time.Second,
			[]string{"./main"},
			req.CustomInput,
		)

	case "java":
		// Write Java code to Main.java
		srcPath := filepath.Join(tmpDir, "Main.java")
		if err := os.WriteFile(srcPath, []byte(req.Code), 0644); err != nil {
			return nil, fmt.Errorf("failed to write java file: %w", err)
		}

		// Compile
		compResult, err := sandbox.RunWithDocker(
			ctx,
			runnerImage("RYP_JAVA_IMAGE", defaultJavaImage),
			tmpDir,
			containerDir,
			5*time.Second,
			[]string{"javac", "Main.java"},
			"",
		)
		if err != nil {
			return nil, fmt.Errorf("compile error: %w", err)
		}
		if compResult.ExitCode != 0 {
			// Compilation failed
			return &models.ExecutionResult{
				Stdout:     compResult.Stdout,
				Stderr:     compResult.Stderr,
				ExitCode:   compResult.ExitCode,
				DurationMs: compResult.DurationMs,
			}, nil
		}

		// Execute
		result, execErr = sandbox.RunWithDocker(
			ctx,
			runnerImage("RYP_JAVA_IMAGE", defaultJavaImage),
			tmpDir,
			containerDir,
			3*time.Second,
			[]string{"java", "Main"},
			req.CustomInput,
		)

	default:
		return nil, fmt.Errorf("unsupported language: %s", req.Language)
	}

	if execErr != nil {
		return nil, fmt.Errorf("execution failed: %w", execErr)
	}

	return &models.ExecutionResult{
		Stdout:            result.Stdout,
		Stderr:            result.Stderr,
		ExitCode:          result.ExitCode,
		TimeLimitExceeded: result.TimeLimitExceeded,
		DurationMs:        result.DurationMs,
	}, nil
}

func normalizeLanguage(language string) string {
	switch strings.ToLower(strings.TrimSpace(language)) {
	case "py", "python3":
		return "python"
	case "c++", "cpp":
		return "cpp"
	default:
		return strings.ToLower(strings.TrimSpace(language))
	}
}

func runnerImage(envName, fallback string) string {
	value := strings.TrimSpace(os.Getenv(envName))
	if value == "" {
		return fallback
	}
	return value
}