import ast
import operator as op
import re
import gradio as gr

# ----------------------------
# Safe arithmetic evaluator
# ----------------------------
ALLOWED_OPERATORS = {
    ast.Add: op.add,
    ast.Sub: op.sub,
    ast.Mult: op.mul,
    ast.Div: op.truediv,
    ast.Mod: op.mod,
    ast.Pow: op.pow,
    ast.UAdd: op.pos,
    ast.USub: op.neg,
}

def _safe_eval_node(node):
    if isinstance(node, ast.Constant) and isinstance(node.value, (int, float)):
        return node.value

    if isinstance(node, ast.BinOp) and type(node.op) in ALLOWED_OPERATORS:
        return ALLOWED_OPERATORS[type(node.op)](
            _safe_eval_node(node.left),
            _safe_eval_node(node.right),
        )

    if isinstance(node, ast.UnaryOp) and type(node.op) in ALLOWED_OPERATORS:
        return ALLOWED_OPERATORS[type(node.op)](_safe_eval_node(node.operand))

    raise ValueError("Unsupported expression")

def safe_eval(expr: str):
    expr = expr.replace("×", "*").replace("÷", "/").replace("−", "-")
    tree = ast.parse(expr, mode="eval")
    return _safe_eval_node(tree.body)

def format_result(value):
    if isinstance(value, float) and value.is_integer():
        return str(int(value))
    return str(value)

# ----------------------------
# Calculator actions
# ----------------------------
def append_value(current, value):
    if current in ("0", "Error"):
        current = ""

    if value in "+-*/":
        if not current and value != "-":
            return "0", "0"
        if current.endswith(("+", "-", "*", "/", ".")):
            current = current[:-1]

    return current + value, current + value

def clear_display():
    return "0", "0"

def backspace(current):
    if current in ("0", "Error", ""):
        return "0", "0"
    new_value = current[:-1]
    if not new_value:
        new_value = "0"
    return new_value, new_value

def evaluate(current):
    try:
        result = safe_eval(current)
        result = format_result(result)
        return result, result
    except:
        return "Error", "Error"

def toggle_sign(current):
    if current in ("0", "Error", ""):
        return "-", "-"

    m = re.search(r"(-?\d+(?:\.\d+)?)$", current)
    if not m:
        return current, current

    start, end = m.span()
    num = m.group(0)

    if num.startswith("-"):
        num = num[1:]
    else:
        num = "-" + num

    new_value = current[:start] + num
    return new_value, new_value

def percent(current):
    if current in ("0", "Error", ""):
        return "0", "0"

    if current.endswith((".", "+", "-", "*", "/")):
        return current, current

    new_value = current + "/100"
    return new_value, new_value

def parens(current):
    if current in ("0", "Error"):
        current = ""

    open_count = current.count("(")
    close_count = current.count(")")

    if not current or current.endswith(("+", "-", "*", "/", "(")):
        ch = "("
    elif open_count > close_count:
        ch = ")"
    else:
        ch = "("

    new_value = current + ch
    return new_value, new_value

def make_append(v):
    def fn(current):
        return append_value(current, v)
    return fn

# ----------------------------
# UI
# ----------------------------
CSS = """
@import url('https://fonts.googleapis.com/css2?family=Orbitron:wght@300;400;600&display=swap');

*{font-family: 'Orbitron', sans-serif !important;}

body, .gradio-container {
    background: #000 !important;
    color: white !important;
}

.phone {
    max-width: 390px;
    margin: 0 auto;
    padding: 16px 14px 20px;
}

.display textarea {
    background: #000 !important;
    color: #fff !important;
    border: none !important;
    box-shadow: none !important;
    text-align: right !important;
    font-size: 72px !important;
    font-weight: 300 !important;
    height: 170px !important;
    padding: 10px 0 0 0 !important;
    resize: none !important;
}

.divider {
    height: 1px;
    background: rgba(255,255,255,0.18);
    margin: 10px 0 18px 0;
}

.topbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: rgba(255,255,255,0.8);
    font-size: 18px;
    margin-bottom: 8px;
    opacity: 0.9;
}

button {
    height: 82px !important;
    min-height: 82px !important;
    border-radius: 999px !important;
    font-size: 30px !important;
    font-weight: 500 !important;
    border: none !important;
    box-shadow: none !important;
}

.digit button {
    background: #272727 !important;
    color: #fff !important;
}

.utility button {
    background: #a5a5a5 !important;
    color: #000 !important;
}

.operator button {
    background: #bfbfbf !important;
    color: #000 !important;
}

.equals button {
    background: #34c759 !important;
    color: #fff !important;
}

.zero button {
    border-radius: 999px !important;
}
"""

with gr.Blocks(css=CSS, title="Calculator") as demo:
    with gr.Column(elem_classes="phone"):
        display = gr.Textbox(
            value="0",
            show_label=False,
            interactive=False,
            container=False,
            lines=1,
            elem_classes="display",
        )
        state = gr.State("0")

        gr.HTML("""
        <div class="divider"></div>
        """)

        # Row 1
        with gr.Row():
            with gr.Column(scale=1, min_width=0):
                gr.Button("C", elem_classes=["utility"]).click(clear_display, None, [state, display])
            with gr.Column(scale=1, min_width=0):
                gr.Button("()", elem_classes=["utility"]).click(parens, state, [state, display])
            with gr.Column(scale=1, min_width=0):
                gr.Button("%", elem_classes=["utility"]).click(percent, state, [state, display])
            with gr.Column(scale=1, min_width=0):
                gr.Button("÷", elem_classes=["operator"]).click(make_append("/"), state, [state, display])

        # Row 2
        with gr.Row():
            for label in ["7", "8", "9"]:
                with gr.Column(scale=1, min_width=0):
                    gr.Button(label, elem_classes=["digit"]).click(make_append(label), state, [state, display])
            with gr.Column(scale=1, min_width=0):
                gr.Button("×", elem_classes=["operator"]).click(make_append("*"), state, [state, display])

        # Row 3
        with gr.Row():
            for label in ["4", "5", "6"]:
                with gr.Column(scale=1, min_width=0):
                    gr.Button(label, elem_classes=["digit"]).click(make_append(label), state, [state, display])
            with gr.Column(scale=1, min_width=0):
                gr.Button("−", elem_classes=["operator"]).click(make_append("-"), state, [state, display])

        # Row 4
        with gr.Row():
            for label in ["1", "2", "3"]:
                with gr.Column(scale=1, min_width=0):
                    gr.Button(label, elem_classes=["digit"]).click(make_append(label), state, [state, display])
            with gr.Column(scale=1, min_width=0):
                gr.Button("+", elem_classes=["operator"]).click(make_append("+"), state, [state, display])

        # Row 5
        with gr.Row():
            with gr.Column(scale=1, min_width=0):
                gr.Button("+/-", elem_classes=["utility"]).click(toggle_sign, state, [state, display])
            with gr.Column(scale=2, min_width=0):
                gr.Button("0", elem_classes=["digit", "zero"]).click(make_append("0"), state, [state, display])
            with gr.Column(scale=1, min_width=0):
                gr.Button(".", elem_classes=["digit"]).click(make_append("."), state, [state, display])
            with gr.Column(scale=1, min_width=0):
                gr.Button("=", elem_classes=["equals"]).click(evaluate, state, [state, display])

demo.launch(server_name="0.0.0.0", server_port=7860)