import os
import sys
import subprocess
from mcp.server.fastmcp import FastMCP

# 1. Initialize with System Instructions
# These instructions tell the LLM *how* to use this server when it connects.
mcp = FastMCP(
    "VibeCodingTutor",
    instructions="""
    This server provides file system access and code execution for a Python Tutor.
    - Always 'list_directory' first to understand the student's current workspace.
    - Use 'read_file' to diagnose errors in existing code.
    - Use 'run_python_script' to verify your examples work before showing them.
    """
)

# --- 2. New Tool: Context Awareness ---
@mcp.tool()
def list_directory() -> str:
    """Lists all files in the current directory to understand the project structure."""
    try:
        files = os.listdir(".")
        # Filter out hidden files/dirs to keep context clean
        visible_files = [f for f in files if not f.startswith('.')]
        if not visible_files:
            return "The directory is empty."
        return "Current Project Files:\n- " + "\n- ".join(visible_files)
    except Exception as e:
        return f"Error listing directory: {str(e)}"

# --- 3. Existing Tools (Enhanced) ---
@mcp.tool()
def write_file(filename: str, content: str) -> str:
    """Writes code or text to a file. Overwrites if exists."""
    try:
        with open(filename, "w") as f:
            f.write(content)
        return f"✅ Successfully wrote {len(content)} bytes to '{filename}'.\nYou can now run this file."
    except Exception as e:
        return f"❌ Error writing file: {str(e)}"

@mcp.tool()
def read_file(filename: str) -> str:
    """Reads a file's content. Use this to debug code."""
    try:
        if not os.path.exists(filename):
            return f"❌ File '{filename}' not found. Did you forget to write it first?"
        with open(filename, "r") as f:
            return f.read()
    except Exception as e:
        return f"Error reading file: {str(e)}"

@mcp.tool()
def run_python_script(filename: str) -> str:
    """Runs a Python script and captures output/errors."""
    try:
        # Check if file exists first to avoid confusing subprocess errors
        if not os.path.exists(filename):
            return f"❌ Cannot run '{filename}' because it does not exist. Write it first."

        # Run with timeout to prevent infinite loops (common with students)
        result = subprocess.run(
            [sys.executable, filename],
            capture_output=True,
            text=True,
            timeout=10 
        )
        
        output = ""
        if result.stdout:
            output += f"[STDOUT]\n{result.stdout}\n"
        if result.stderr:
            output += f"[STDERR]\n{result.stderr}\n"
            
        if not output:
            return "[Process finished with no output]"
            
        return output
    except subprocess.TimeoutExpired:
        return "❌ Error: Script execution timed out (limit: 10s). Check for infinite loops."
    except Exception as e:
        return f"Execution failed: {str(e)}"

# --- 4. New Resource: Static Knowledge ---
# The agent can "read" this resource URL to get its core curriculum
@mcp.resource("tutor://curriculum")
def get_curriculum() -> str:
    """Returns the standard teaching curriculum for this session."""
    return """
    # Python Vibe Coding Curriculum
    1. Basics: Variables, Loops, functions.
    2. Data: Lists, Dictionaries, Sets.
    3. Advanced: Decorators, Generators, Context Managers.
    4. Data Science: Pandas, Matplotlib.
    
    TEACHING STYLE:
    - Don't just explain. CODING IS DOING.
    - Always create a file, run it, and show the output.
    - If the user is wrong, be encouraging but precise.
    """

if __name__ == "__main__":
    mcp.run()