import re

class BASEInterpreter:
    def __init__(self):
        self.variables = {}

    def run(self, filename):
        try:
            with open(filename, 'r') as f:
                lines = f.readlines()
                if self.check_structure(lines):
                    self.execute(lines)
                else:
                    print("Error: BASE program structure is incorrect.")
        except FileNotFoundError:
            print(f"Error: File '{filename}' not found.")

    def check_structure(self, lines):
        return lines[0].strip() == "START" and lines[-1].strip() == "END"

    def execute(self, lines):
        i = 1
        while i < len(lines) - 1:
            line = lines[i].strip()

            if line.startswith("COMMENT"):
                i += 1
                continue

            elif line.startswith("SET"):
                self.handle_set(line)

            elif line.startswith("SAY"):
                self.handle_say(line)

            elif line.startswith("WAIT"):
                self.handle_wait(line)

            elif line.startswith("IF"):
                condition = line[3:].strip()
                if self.evaluate_condition(condition):
                    i += 1
                    while i < len(lines) - 1 and not lines[i].strip().startswith("ELSE") and not lines[i].strip().startswith("ENDIF"):
                        self.execute_line(lines[i])
                        i += 1
                    if i < len(lines) - 1 and lines[i].strip().startswith("ELSE"):
                        i += 1
                        while i < len(lines) - 1 and not lines[i].strip().startswith("ENDIF"):
                            i += 1
                else:
                    while i < len(lines) - 1 and not lines[i].strip().startswith("ELSE") and not lines[i].strip().startswith("ENDIF"):
                        i += 1
                    if i < len(lines) - 1 and lines[i].strip().startswith("ELSE"):
                        i += 1
                        while i < len(lines) - 1 and not lines[i].strip().startswith("ENDIF"):
                            self.execute_line(lines[i])
                            i += 1

            i += 1

    def evaluate_condition(self, condition):
        parts = re.split(r'(==|!=|>=|<=|>|<)', condition)
        var_name = parts[0].strip()
        operator = parts[1].strip()
        value_str = parts[2].strip()

        if var_name.startswith("var(") and var_name.endswith(")"):
            var_name = var_name[4:-1]
        var_value = self.variables.get(var_name)

        if var_value is None:
            return False

        try:
            value = float(value_str[:-1])
        except ValueError:
            return False

        if operator == "==":
            return var_value == value
        elif operator == "!=":
            return var_value != value
        elif operator == ">=":
            return var_value >= value
        elif operator == "<=":
            return var_value <= value
        elif operator == ">":
            return var_value > value
        elif operator == "<":
            return var_value < value
        else:
            return False

    def execute_line(self, line):
        line = line.strip()
        if line.startswith("SET"):
            self.handle_set(line)
        elif line.startswith("SAY"):
            self.handle_say(line)
        elif line.startswith("WAIT"):
            self.handle_wait(line)
        elif line.startswith("ADD"):
            self.handle_math_operation("ADD", line)
        elif line.startswith("SUBTRACT"):
            self.handle_math_operation("SUBTRACT", line)
        elif line.startswith("MULTIPLY"):
            self.handle_math_operation("MULTIPLY", line)
        elif line.startswith("DIVIDE"):
            self.handle_math_operation("DIVIDE", line)

    def handle_set(self, line):
        _, rest = line.split(' ', 1)
        var_name, value = rest.split(' = ')
        var_name = var_name.strip()
        value = value.strip()
        self.variables[var_name] = value

    def handle_say(self, line):
        _, rest = line.split(' ', 1)
        if rest.startswith("text(") and rest.endswith(")"):
            text = rest[5:-1]
            parsed_text = self.parse_text(text)
            print(parsed_text)
        elif rest.startswith("num(") and rest.endswith(")"):
            num = rest[4:-1]
            print(num)
        else:
            parsed_text = self.parse_text(rest)
            print(parsed_text)

    def parse_text(self, text):
        if text.startswith("text(") and text.endswith(")"):
            return text[5:-1]

        if text.startswith("num(") and text.endswith(")"):
            return text[4:-1]

        def replace_var(match):
            var_name = match.group(1)
            return self.variables.get(var_name, f"Error: Variable '{var_name}' not found.")

        return re.sub(r'var\((\w+)\)', replace_var, text)

    def handle_wait(self, line):
        _, time_in_seconds = line.split(' ', 1)
        time_in_seconds = float(time_in_seconds.strip())
        import time
        time.sleep(time_in_seconds)

    def handle_math_operation(self, operation, line):
        _, values = line.split(' ', 1)
        values = values.strip().split()
        operation_result = None

        if operation == "ADD":
            operation_result = sum(self.get_value(val) for val in values)
        elif operation == "SUBTRACT":
            operation_result = self.get_value(values[0])
            for val in values[1:]:
                operation_result -= self.get_value(val)
        elif operation == "MULTIPLY":
            operation_result = 1
            for val in values:
                operation_result *= self.get_value(val)
        elif operation == "DIVIDE":
            operation_result = self.get_value(values[0])
            for val in values[1:]:
                operation_result /= self.get_value(val)

        first_var = values[0]
        self.variables[first_var] = str(operation_result)
        print(operation_result)

    def get_value(self, val):
        if val.isdigit() or (val[0] == '-' and val[1:].isdigit()):
            return float(val)
        elif val in self.variables:
            return float(self.variables[val])
        else:
            return 0.0

if __name__ == "__main__":
    interpreter = BASEInterpreter()
    filename = input("Enter BASE file name to execute: ")
    interpreter.run(filename)
    input("Press Enter to exit...")