from flask import Flask, request, jsonify
import socket
import sys

# Command line arguments: python backend.py <host> <port> [password]
if len(sys.argv) < 3:
    print("Usage: python backend.py <valkey_host> <valkey_port> [valkey_password]")
    sys.exit(1)

VALKEY_HOST = sys.argv[1]
VALKEY_PORT = int(sys.argv[2])
VALKEY_PASSWORD = sys.argv[3] if len(sys.argv) > 3 else ""

app = Flask(__name__)
sock = None

def init_socket():
    global sock
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.connect((VALKEY_HOST, VALKEY_PORT))
    if VALKEY_PASSWORD:
        auth_cmd = f"*2\r\n$4\r\nAUTH\r\n${len(VALKEY_PASSWORD)}\r\n{VALKEY_PASSWORD}\r\n"
        sock.sendall(auth_cmd.encode())
        sock.recv(1024)

@app.route('/api/user/role', methods=['POST'])
def set_user_role():
    global sock
    try:
        data = request.json
        username = data.get('username')
        role = data.get('role')
        print(f"[SET] {username} = {role}")

        key = f"user:{username}:role"
        set_cmd = f"*3\r\n$3\r\nSET\r\n${len(key)}\r\n{key}\r\n${len(role)}\r\n{role}\r\n"
        sock.sendall(set_cmd.encode())
        sock.recv(1024)
        return jsonify({"status": "success", "username": username, "role": role})
    except Exception as e:
        return jsonify({"status": "error", "error": str(e)}), 500

@app.route('/api/process', methods=['POST'])
def process_script():
    global sock
    try:
        data = request.json
        script = data.get('script', '')
        print(f"[EVAL] Lua script executed (injection in buffer)")

        eval_cmd = f"*3\r\n$4\r\nEVAL\r\n${len(script)}\r\n{script}\r\n$1\r\n0\r\n"
        sock.sendall(eval_cmd.encode())

        # Read ONLY the first line, leave injection in buffer
        error_line = b""
        while not error_line.endswith(b"\r\n"):
            chunk = sock.recv(1)
            if not chunk:
                break
            error_line += chunk

        return jsonify({"status": "error", "error": error_line.decode().strip()}), 500
    except Exception as e:
        return jsonify({"status": "error", "error": str(e)}), 500

@app.route('/api/user/role', methods=['GET'])
def get_user_role():
    global sock
    username = request.args.get('username', 'victim')

    try:
        key = f"user:{username}:role"
        get_cmd = f"*2\r\n$3\r\nGET\r\n${len(key)}\r\n{key}\r\n"
        sock.sendall(get_cmd.encode())

        first_line = b""
        while not first_line.endswith(b"\r\n"):
            chunk = sock.recv(1)
            if not chunk:
                break
            first_line += chunk

        if not first_line:
            print(f"[GET] Error: Empty response")
            return jsonify({"status": "error", "error": "Empty response"}), 500

        first_line_str = first_line.decode().strip()

        if first_line_str.startswith("$"):
            length_str = first_line_str[1:]
            if length_str == "-1":
                print(f"[GET] {username} = None")
                return jsonify({"status": "success", "username": username, "role": None})

            length = int(length_str)
            data_bytes = b""
            while len(data_bytes) < length:
                chunk = sock.recv(length - len(data_bytes))
                if not chunk:
                    break
                data_bytes += chunk
            sock.recv(2)  # trailing \r\n

            data = data_bytes.decode()
            print(f"[GET] {username} = {data}")
            return jsonify({"status": "success", "username": username, "role": data})

        elif first_line_str.startswith("+"):
            # Simple string response
            data = first_line_str[1:]
            print(f"[GET] {username} = {data}")
            return jsonify({"status": "success", "username": username, "role": data})

        elif first_line_str.startswith("-"):
            print(f"[GET] Error: {first_line_str}")
            return jsonify({"status": "error", "error": first_line_str}), 500

        print(f"[GET] Unexpected: '{first_line_str}'")
        return jsonify({"status": "error", "error": f"Unexpected response: {first_line_str}"}), 500
    except Exception as e:
        return jsonify({"status": "error", "error": str(e)}), 500

if __name__ == '__main__':
    print(f"Backend server starting... ({VALKEY_HOST}:{VALKEY_PORT})")
    init_socket()
    app.run(host='0.0.0.0', port=5001, debug=False)