app.py

"""
Python Code Evaluator — SE-Group1
COS60011 Technology Design Project
"""

# ---------------------------------------------------------------------------
# IMPORTS (all at top)
# ---------------------------------------------------------------------------
import os
import re
import ast
import time
from collections import deque
from dotenv import load_dotenv
import gradio as gr
from google import genai

load_dotenv()


# ---------------------------------------------------------------------------
# MODULE 3 — Pre-processing Module
# ---------------------------------------------------------------------------
def build_prompt(description: str, code: str) -> str:
    prompt = f"""<start_of_turn>user
### ROLE
You are an expert Python code reviewer. Your sole task is to determine whether the
provided Python code correctly implements the behaviour described in the user's
requirements description.
### CONTEXT
Developers sometimes write code that does not fully satisfy the requirements they
were given. You will analyse the semantic relationship between a natural-language
description and a Python code snippet, then produce a structured evaluation report.
### INPUT DATA
**Requirements Description:**
{description.strip()}
**Python Code:**
```python
{code.strip()}
```
### TASK
1. Read the requirements description carefully.
2. Analyse the Python code line by line.
3. Determine whether the code fulfils ALL requirements stated in the description.
4. Estimate an accuracy percentage (0–100) reflecting how completely the code
   matches the description.
5. List any specific requirements that are missing or incorrectly implemented.
### CONSTRAINTS
- Do NOT execute the code.
- Base your evaluation solely on static code analysis and logical reasoning.
- Keep feedback concise, clear, and actionable.
- Your response MUST follow the output format exactly.
### OUTPUT FORMAT
Respond only with the following structure — no extra text before or after:
RESULT: <PASS or FAIL>
ACCURACY: <integer 0-100>%
SUMMARY: <one sentence overall assessment>
ISSUES:
- <issue 1, or "None" if code fully matches the description>
- <issue 2>
...
<end_of_turn>
<start_of_turn>model
"""
    return prompt


# ---------------------------------------------------------------------------
# MODULE 4 — Generation Module
# ---------------------------------------------------------------------------
MODEL_ID       = "gemma-4-31b-it"
GOOGLE_API_KEY = os.environ.get("GOOGLE_API_KEY")

def generate_response(prompt: str) -> str:
    if not GOOGLE_API_KEY:
        return (
            "⚠️ Error: API Key not found! "
            "Please configure GOOGLE_API_KEY in Settings → Variables and secrets."
        )
    try:
        client   = genai.Client(api_key=GOOGLE_API_KEY)
        response = client.models.generate_content(model=MODEL_ID, contents=prompt)
        return response.text
    except Exception as e:
        return f"❌ An error occurred during generation: {str(e)}"


# ---------------------------------------------------------------------------
# MODULE 5 — Output Module
# ---------------------------------------------------------------------------
def parse_output(raw: str) -> dict:
    if "<start_of_turn>model" in raw:
        raw = raw.split("<start_of_turn>model")[-1]

    result_match   = re.search(r"RESULT:\s*(PASS|FAIL)", raw, re.IGNORECASE)
    accuracy_match = re.search(r"ACCURACY:\s*(\d{1,3})%?", raw, re.IGNORECASE)
    summary_match  = re.search(r"SUMMARY:\s*(.+)", raw, re.IGNORECASE)
    issues_match   = re.search(r"ISSUES:\s*([\s\S]+)", raw, re.IGNORECASE)

    result   = result_match.group(1).upper()  if result_match   else "UNKNOWN"
    accuracy = int(accuracy_match.group(1))   if accuracy_match else -1
    summary  = summary_match.group(1).strip() if summary_match  else "Could not extract summary."

    if issues_match:
        raw_issues = issues_match.group(1).strip()
        issues = [
            line.lstrip("-•* ").strip()
            for line in raw_issues.splitlines()
            if line.strip() and line.strip() not in ("-", "•")
        ]
    else:
        issues = ["Could not extract issues from model response."]

    return {
        "result":   result,
        "accuracy": accuracy,
        "summary":  summary,
        "issues":   issues,
        "raw":      raw.strip(),
    }


def format_for_display(parsed: dict) -> tuple[str, str, str]:
    emoji   = "✅" if parsed["result"] == "PASS" else ("❌" if parsed["result"] == "FAIL" else "⚠️")
    verdict = f"{emoji}  {parsed['result']}"
    acc_str = f"{parsed['accuracy']}%" if parsed["accuracy"] >= 0 else "N/A"
    metrics = f"Accuracy: {acc_str}\n\nSummary: {parsed['summary']}"
    issues_text = "\n".join(f"• {issue}" for issue in parsed["issues"])
    return verdict, metrics, issues_text


# ---------------------------------------------------------------------------
# MODULE 2 — Validation & Flow Management Module
# ---------------------------------------------------------------------------
MIN_DESCRIPTION_CHARS = 20
MAX_DESCRIPTION_CHARS = 3000
MIN_CODE_CHARS        = 10
MAX_CODE_CHARS        = 8000
MAX_CODE_LINES        = 300

FORBIDDEN_PATTERNS = [
    r"ignore (all |previous |above )?instructions",
    r"disregard (all |previous |above )?instructions",
    r"you are now",
    r"act as (a |an )?",
    r"<\s*(script|iframe|object|embed)",
    r"system\s*prompt",
    r"jailbreak",
]

PYTHON_KEYWORDS = {
    "def", "class", "import", "from", "return", "if", "else", "elif",
    "for", "while", "try", "except", "with", "lambda", "yield", "pass",
    "raise", "assert", "in", "not", "and", "or", "True", "False", "None",
    "print", "len", "range", "self",
}

class RateLimiter:
    def __init__(self, max_calls: int = 5, window_seconds: int = 60):
        self.max_calls      = max_calls
        self.window_seconds = window_seconds
        self._timestamps: deque = deque()

    def is_allowed(self) -> tuple[bool, str]:
        now = time.time()
        while self._timestamps and now - self._timestamps[0] > self.window_seconds:
            self._timestamps.popleft()
        if len(self._timestamps) >= self.max_calls:
            wait = int(self.window_seconds - (now - self._timestamps[0])) + 1
            return False, (
                f"⏳ Rate limit reached — {self.max_calls} requests in "
                f"{self.window_seconds}s. Please wait ~{wait}s and try again."
            )
        self._timestamps.append(now)
        return True, ""

_rate_limiter = RateLimiter(max_calls=5, window_seconds=60)

def _check_forbidden(text: str) -> str | None:
    lower = text.lower()
    for pattern in FORBIDDEN_PATTERNS:
        if re.search(pattern, lower):
            return (
                "Input contains disallowed content. "
                "Please remove prompt-injection or HTML patterns and try again."
            )
    return None

def _looks_like_python(code: str) -> tuple[bool, str]:
    tokens = set(re.findall(r"[A-Za-z_]\w*", code))
    if not tokens.intersection(PYTHON_KEYWORDS):
        return False, (
            "🐍 The code doesn't appear to be Python — no recognisable Python "
            "keywords found (e.g. def, class, import, return). "
            "Please submit Python code only."
        )
    try:
        ast.parse(code)
    except SyntaxError as exc:
        line_hint = f" (line {exc.lineno})" if exc.lineno else ""
        return False, (
            f"🐍 Python syntax error{line_hint}: {exc.msg}. "
            "Please fix the syntax error before evaluating."
        )
    return True, ""

def validate_inputs(description: str, code: str) -> list[str]:
    errors: list[str] = []

    if not description or not description.strip():
        errors.append("📋 Requirements description is required.")
    if not code or not code.strip():
        errors.append("🐍 Python code is required.")
    if errors:
        return errors

    desc, code_ = description.strip(), code.strip()

    if len(desc) < MIN_DESCRIPTION_CHARS:
        errors.append(f"📋 Description too short ({len(desc)} chars) — minimum is {MIN_DESCRIPTION_CHARS} characters.")
    if len(code_) < MIN_CODE_CHARS:
        errors.append(f"🐍 Code too short ({len(code_)} chars) — minimum is {MIN_CODE_CHARS} characters.")
    if len(desc) > MAX_DESCRIPTION_CHARS:
        errors.append(f"📋 Description too long ({len(desc):,} chars) — max is {MAX_DESCRIPTION_CHARS:,} characters.")
    if len(code_) > MAX_CODE_CHARS:
        errors.append(f"🐍 Code too long ({len(code_):,} chars) — max is {MAX_CODE_CHARS:,} characters.")
    if len(code_.splitlines()) > MAX_CODE_LINES:
        errors.append(f"🐍 Code has too many lines ({len(code_.splitlines())}) — max is {MAX_CODE_LINES} lines.")

    if err := _check_forbidden(desc):
        errors.append(f"📋 {err}")
    if err := _check_forbidden(code_):
        errors.append(f"🐍 {err}")

    if not errors:
        is_python, py_error = _looks_like_python(code_)
        if not is_python:
            errors.append(py_error)

    if not errors:
        allowed, rate_msg = _rate_limiter.is_allowed()
        if not allowed:
            errors.append(rate_msg)

    return errors

def validate_and_evaluate(description: str, code: str):
    errors = validate_inputs(description, code)
    if errors:
        return "", "", "", "\n".join(f"{i+1}. {e}" for i, e in enumerate(errors))

    if not GOOGLE_API_KEY:
        return "", "", "", "❌ GOOGLE_API_KEY secret not set in Space Settings."

    prompt = build_prompt(description, code)
    try:
        raw_output = generate_response(prompt)
    except Exception as exc:
        return "", "", "", f"❌ Model error: {exc}"

    parsed = parse_output(raw_output)
    verdict, metrics, issues = format_for_display(parsed)
    return verdict, metrics, issues, ""


# ---------------------------------------------------------------------------
# MODULE 1 — UI Module
# ---------------------------------------------------------------------------

CUSTOM_CSS = """
@import url('https://fonts.googleapis.com/css2?family=Space+Mono:wght@400;700&family=DM+Sans:ital,wght@0,300;0,400;0,500;0,600;1,400&display=swap');
*, *::before, *::after { box-sizing: border-box; }
body, .gradio-container {
    font-family: 'DM Sans', sans-serif !important;
    background: #0D0F14 !important;
    color: #E8EAF0 !important;
}
.gradio-container {
    max-width: 1140px !important;
    margin: 0 auto !important;
    padding: 32px 24px !important;
}
.eval-header {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 0 0 28px;
    border-bottom: 1px solid #2E3140;
    margin-bottom: 28px;
}
.eval-header .logo {
    width: 44px; height: 44px;
    border-radius: 10px;
    background: linear-gradient(135deg, #534AB7 0%, #1D9E75 100%);
    display: flex; align-items: center; justify-content: center;
    flex-shrink: 0;
    font-size: 22px; line-height: 1;
}
.eval-header h1 {
    font-size: 20px !important;
    font-weight: 600 !important;
    letter-spacing: -0.3px !important;
    color: #E8EAF0 !important;
    margin: 0 !important;
}
.eval-header .model-badge {
    margin-left: auto;
    font-family: 'Space Mono', monospace;
    font-size: 10px;
    background: #1E2028;
    border: 1px solid #3A3E52;
    color: #6A6E80;
    padding: 4px 10px;
    border-radius: 4px;
    letter-spacing: 1.5px;
    white-space: nowrap;
}
.gradio-textbox textarea,
.gradio-code textarea,
.gradio-textbox input {
    background: #161820 !important;
    border: 1px solid #2E3140 !important;
    border-radius: 10px !important;
    color: #E8EAF0 !important;
    font-family: 'DM Sans', sans-serif !important;
    font-size: 13.5px !important;
    line-height: 1.7 !important;
    padding: 14px 16px !important;
    transition: border-color 0.15s !important;
    resize: vertical !important;
}
.gradio-textbox textarea:focus,
.gradio-code textarea:focus {
    border-color: #534AB7 !important;
    outline: none !important;
    box-shadow: 0 0 0 3px rgba(83, 74, 183, 0.15) !important;
}
.gradio-textbox textarea::placeholder {
    color: #4A4E60 !important;
}
#code-input textarea {
    font-family: 'Space Mono', monospace !important;
    font-size: 12.5px !important;
    line-height: 1.65 !important;
}
.gradio-textbox label span,
.gradio-code label span {
    font-family: 'DM Sans', sans-serif !important;
    font-size: 13px !important;
    font-weight: 700 !important;
    color: #E8EAF0 !important;
    text-transform: uppercase !important;
    letter-spacing: 0.8px !important;
}
#eval-btn {
    background: #534AB7 !important;
    border: none !important;
    color: #fff !important;
    font-family: 'DM Sans', sans-serif !important;
    font-size: 14px !important;
    font-weight: 500 !important;
    padding: 12px 32px !important;
    border-radius: 8px !important;
    cursor: pointer !important;
    transition: background 0.15s, transform 0.1s !important;
    letter-spacing: -0.1px !important;
}
#eval-btn:hover { background: #7F77DD !important; transform: translateY(-1px) !important; }
#eval-btn:active { transform: translateY(0) !important; }
#clear-btn {
    background: transparent !important;
    border: 1px solid #3A3E52 !important;
    color: #9DA0B0 !important;
    font-family: 'DM Sans', sans-serif !important;
    font-size: 13px !important;
    padding: 12px 20px !important;
    border-radius: 8px !important;
    cursor: pointer !important;
    transition: border-color 0.15s, color 0.15s !important;
}
#clear-btn:hover { border-color: #7F77DD !important; color: #E8EAF0 !important; }
.results-heading {
    font-size: 11px !important;
    font-weight: 500 !important;
    color: #6A6E80 !important;
    text-transform: uppercase !important;
    letter-spacing: 1px !important;
    padding: 0 0 16px !important;
    border-bottom: 1px solid #2E3140 !important;
    margin-bottom: 20px !important;
}
#verdict-out textarea {
    background: #161820 !important; border: 1px solid #2E3140 !important;
    border-radius: 10px !important; font-family: 'Space Mono', monospace !important;
    font-size: 26px !important; font-weight: 700 !important;
    text-align: center !important; padding: 20px !important;
    color: #E8EAF0 !important; cursor: default !important;
}
#accuracy-out textarea {
    background: #161820 !important; border: 1px solid #2E3140 !important;
    border-radius: 10px !important; font-family: 'Space Mono', monospace !important;
    font-size: 26px !important; font-weight: 700 !important;
    text-align: center !important; padding: 20px !important;
    color: #E8EAF0 !important; cursor: default !important;
}
#summary-out textarea {
    background: #161820 !important; border: 1px solid #2E3140 !important;
    border-radius: 10px !important; font-family: 'DM Sans', sans-serif !important;
    font-size: 13.5px !important; line-height: 1.7 !important;
    padding: 16px !important; color: #C0C3D0 !important; cursor: default !important;
}
#issues-out textarea {
    background: #161820 !important; border: 1px solid #2E3140 !important;
    border-radius: 10px !important; font-family: 'DM Sans', sans-serif !important;
    font-size: 13.5px !important; line-height: 1.8 !important;
    padding: 16px !important; color: #C0C3D0 !important;
    cursor: default !important; min-height: 120px !important;
}
#error-out textarea {
    background: #1A0E0E !important; border: 1px solid #5a2020 !important;
    border-radius: 10px !important; font-family: 'DM Sans', sans-serif !important;
    font-size: 13.5px !important; padding: 14px 16px !important;
    color: #F0997B !important; cursor: default !important;
}
.divider { height: 1px; background: #2E3140; margin: 20px 0; }
footer { display: none !important; }
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: #3A3E52; border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: #534AB7; }
"""

HEADER_HTML = """
<div class="eval-header">
  <div class="logo">🔍</div>
  <div><h1>Python Code Evaluator</h1></div>
  <div class="model-badge">GEMMA-4 · 31B-IT</div>
</div>
"""

RESULTS_HEADING_HTML = """
<div class="divider"></div>
<div class="results-heading">⬡ &nbsp; Evaluation Results</div>
"""

INPUT_HINT_HTML = """
<div style="font-size:12px;color:#4A4E60;margin-top:-4px;padding-bottom:4px;">
  Tip — paste your description and code above, then click
  <strong style="color:#7F77DD">Evaluate</strong>.
</div>
"""


def build_ui(evaluate_fn):

    def _split_metrics(metrics_str: str):
        acc, summary = "", ""
        if not metrics_str:
            return acc, summary
        for line in metrics_str.splitlines():
            if line.startswith("Accuracy:"):
                acc = line.replace("Accuracy:", "").strip()
            elif line.startswith("Summary:"):
                summary = line.replace("Summary:", "").strip()
        return acc, summary

    def _ui_evaluate(description: str, code: str):
        verdict, metrics, issues, error = evaluate_fn(description, code)
        accuracy, summary = _split_metrics(metrics)
        if "PASS" in verdict.upper():
            verdict_display = "✅  PASS"
        elif "FAIL" in verdict.upper():
            verdict_display = "❌  FAIL"
        else:
            verdict_display = verdict or ""
        return verdict_display, accuracy, summary, issues, error

    with gr.Blocks(title="Python Code Evaluator") as demo:

        gr.HTML(HEADER_HTML)

        with gr.Row(equal_height=True):
            description_input = gr.Textbox(
                label="Requirements Description",
                placeholder=(
                    "Describe what the Python code is supposed to do…\n\n"
                    "Example: Write a function that accepts a list of integers "
                    "and returns the sum of all even numbers. It should handle "
                    "empty lists by returning 0 and ignore non-integer values."
                ),
                lines=10,
                max_lines=20,
                elem_id="desc-input",
            )
            code_input = gr.Textbox(
                label="Python Code",
                placeholder=(
                    "# Paste your Python code here…\n\n"
                    "# Note: Ensure proper indentation for accurate evaluation.\n\n"
                    "def example(numbers):\n"
                    "    total = 0\n"
                    "    for item in numbers:\n"
                    "        if item % 2 == 0:\n"
                    "            total += item\n"
                    "    return total\n"
                ),
                lines=10,
                max_lines=30,
                elem_id="code-input",
            )

        gr.HTML(INPUT_HINT_HTML)

        with gr.Row():
            eval_btn  = gr.Button("Evaluate", variant="primary",
                                  elem_id="eval-btn", scale=0)
            clear_btn = gr.Button("Clear", variant="secondary",
                                  elem_id="clear-btn", scale=0)

        gr.HTML(RESULTS_HEADING_HTML)

        with gr.Row(equal_height=True):
            verdict_out  = gr.Textbox(label="Verdict",   interactive=False, elem_id="verdict-out",  scale=1)
            accuracy_out = gr.Textbox(label="Accuracy",  interactive=False, elem_id="accuracy-out", scale=1)
            summary_out  = gr.Textbox(label="Summary",   interactive=False, elem_id="summary-out",  scale=2, lines=3)

        issues_out = gr.Textbox(label="Issues Detected", interactive=False, lines=5,      elem_id="issues-out")
        error_out  = gr.Textbox(label="Status / Errors", interactive=False, visible=True, elem_id="error-out")

        gr.HTML("""
        <div style="text-align:right;font-size:11px;color:#4A4E60;margin-top:8px;">
          Press <kbd style="background:#1E2028;border:1px solid #3A3E52;border-radius:4px;
          padding:2px 6px;font-family:'Space Mono',monospace;font-size:10px;color:#9DA0B0;">
          Ctrl+Enter</kbd> inside any input to evaluate
        </div>
        """)

        outputs = [verdict_out, accuracy_out, summary_out, issues_out, error_out]
        eval_btn.click(fn=_ui_evaluate, inputs=[description_input, code_input], outputs=outputs)
        description_input.submit(fn=_ui_evaluate, inputs=[description_input, code_input], outputs=outputs)
        code_input.submit(fn=_ui_evaluate, inputs=[description_input, code_input], outputs=outputs)

        def _clear():
            return "", "", "", "", "", ""

        clear_btn.click(
            fn=_clear,
            inputs=[],
            outputs=[description_input, code_input,
                     verdict_out, accuracy_out, summary_out, issues_out],
        )

    return demo


# ---------------------------------------------------------------------------
# ENTRY POINT
# ---------------------------------------------------------------------------
if __name__ == "__main__":
    app = build_ui(validate_and_evaluate)
    app.launch(server_name="0.0.0.0", server_port=7860, share=False,
               show_error=True, css=CUSTOM_CSS)