import re
import subprocess
import sys

# 1. Get student answer and strip 'public' from class/interface/record
student_answer = """{{ STUDENT_ANSWER | e('py') }}"""

# remove 'public' to cope with multiple compilation units in one answer
student_answer = re.sub(
    r'\bpublic\s+(abstract\s+class|class|interface|record)\b',
    r'\1',
    student_answer
)

# 2. Extract classname from student code
match = re.search(
    r'\b(?:abstract\s+)?(class|interface|record)\s+([_a-zA-Z][_a-zA-Z0-9]*)\b',
    student_answer
)

if not match:
    print("The answer didn't contain a class, interface or record.", file=sys.stderr)
    sys.exit(1)

classname = match.group(2)

# 3. Write student's Java code to file
# with open(f"{classname}.java", "w") as f:
with open("__studentAnswer__.java", "w") as f:
    f.write(student_answer)

# limit the amount of compilation error output 
def print_first_compile_error(stderr_text, stream=sys.stderr):
    lines = stderr_text.strip().splitlines()

    for i in range(min(3, len(lines))):
        print(lines[i], file=stream)
    sys.exit(1)

# 5. Compile student + tester files
cargs = ["javac21",
    "-J-Xss512k",
    "-J-Xmx64m",
    "-J-XX:CompressedClassSpaceSize=32m",
    "-J-Xrs",
    "-J-XX:ActiveProcessorCount=1"]

# first try compile by itself without template    
# compile_cmd1 = cargs + [f"{classname}.java"]
compile_cmd1 = cargs + ["__studentAnswer__.java"]

comp = subprocess.run(compile_cmd1, capture_output=True, text=True)

if comp.returncode != 0:   
    # print_first_compile_error(comp.stderr)
    print(comp.stderr, file=sys.stderr)
    sys.exit(2)

# 4. Only now write __tester__.java using Twig syntax
with open("__tester__.java", "w") as f:
    f.write("""
    public class __tester__ {
    
        private static final String SEPARATOR = "#<ab@17943918#@>#";
        
        public static void main(String[] args) {
            __tester__ main = new __tester__();
            main.runTests();
        }
        
        public void runTests() {
            try {
                {% for TEST in TESTCASES %}
                {
                    {{ TEST.testcode }}
                    {% if not loop.last %}
                        System.out.println(SEPARATOR);
                    {% endif %}
                }
                {% endfor %}    
            }
            catch (Throwable e) {
                if (e instanceof java.awt.HeadlessException) {
                    System.err.println("GUI libraries are not supported here.");
                } else {
                    System.out.println("Exception: " + e);
                }
            }
        }
    }
    """)

compile_cmd2 = cargs + ["__tester__.java"]

comp = subprocess.run(compile_cmd2, capture_output=True, text=True)

if comp.returncode != 0:
    print_first_compile_error(comp.stderr)
    sys.exit(2)

# 6. Run compiled Java program using java21
# Here the args don't use -J
rargs = ["java21",
    "-Xss512k",
    "-Xmx64m",
    "-XX:CompressedClassSpaceSize=32m",
    "-Xrs", 
    "-XX:ActiveProcessorCount=1"]
    
run_cmd = rargs + ["__tester__"]

# no need to capture output
run = subprocess.run(run_cmd, text=True)