import json
import logging
import re
from flask import Flask, request, jsonify
from routes import app

# Configure logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

# Global Symbol table and Output collector
symbols = {}
output = []

# Regular expressions for tokenizing
TOKEN_REGEX = re.compile(r'\s*(?:(\()|(\))|(".*?")|([^()\s]+))')

# Exception class for interpreter errors
class InterpreterError(Exception):
    def __init__(self, message, line):
        self.message = message
        self.line = line

# Helper functions for type checking and conversion
def is_number(value):
    return isinstance(value, int) or isinstance(value, float)

def convert_str(value):
    if isinstance(value, str):
        return value
    elif is_number(value):
        if isinstance(value, float):
            # Format to remove trailing zeros, keeping up to 4 decimal places
            return f"{value:.4f}".rstrip('0').rstrip('.') if '.' in f"{value:.4f}" else f"{value:.4f}"
        elif isinstance(value, int):
            return str(value)
    elif isinstance(value, bool):
        return "true" if value else "false"
    elif value is None:
        return "null"
    else:
        raise ValueError("Unsupported type for str conversion")

# Function implementations
def func_puts(args, line):
    if len(args) != 1:
        raise InterpreterError("puts expects exactly one argument", line)
    arg = args[0]
    if not isinstance(arg, str):
        raise InterpreterError("puts expects a string argument", line)
    logger.info(f"puts: Appending '{arg}' to output")
    output.append(arg)
    return None

def func_set(args, line):
    if len(args) != 2:
        raise InterpreterError("set expects exactly two arguments", line)
    var_name, value = args
    if not isinstance(var_name, str):
        raise InterpreterError("set expects the first argument to be a string (variable name)", line)
    # Variable names must be alphabetic
    if not re.fullmatch(r'[A-Za-z]+', var_name):
        raise InterpreterError("Invalid variable name format", line)
    if var_name in symbols:
        raise InterpreterError("Cannot reassign to an existing constant", line)
    symbols[var_name] = value
    logger.info(f"set: '{var_name}' set to '{value}'")
    return None

def func_concat(args, line):
    if len(args) != 2:
        raise InterpreterError("concat expects exactly two arguments", line)
    a, b = args
    if not isinstance(a, str) or not isinstance(b, str):
        raise InterpreterError("concat expects string arguments", line)
    result = a + b
    logger.info(f"concat: '{a}' + '{b}' = '{result}'")
    return result

def func_substring(args, line):
    if len(args) != 3:
        raise InterpreterError("substring expects exactly three arguments", line)
    source, start, end = args
    if not isinstance(source, str):
        raise InterpreterError("substring expects the first argument to be a string", line)
    if not is_number(start) or not is_number(end):
        raise InterpreterError("substring expects start and end indices to be numbers", line)
    start = int(start)
    end = int(end)
    if start < 0 or end < 0 or start > len(source) or end > len(source) or start > end:
        raise InterpreterError("substring indices out of bounds", line)
    result = source[start:end]
    logger.info(f"substring: '{source}'[{start}:{end}] = '{result}'")
    return result

def func_lowercase(args, line):
    if len(args) != 1:
        raise InterpreterError("lowercase expects exactly one argument", line)
    a = args[0]
    if not isinstance(a, str):
        raise InterpreterError("lowercase expects a string argument", line)
    result = a.lower()
    logger.info(f"lowercase: '{a}' -> '{result}'")
    return result

def func_uppercase(args, line):
    if len(args) != 1:
        raise InterpreterError("uppercase expects exactly one argument", line)
    a = args[0]
    if not isinstance(a, str):
        raise InterpreterError("uppercase expects a string argument", line)
    result = a.upper()
    logger.info(f"uppercase: '{a}' -> '{result}'")
    return result

def func_replace(args, line):
    if len(args) != 3:
        raise InterpreterError("replace expects exactly three arguments", line)
    source, target, replacement = args
    if not isinstance(source, str) or not isinstance(target, str) or not isinstance(replacement, str):
        raise InterpreterError("replace expects string arguments", line)
    result = source.replace(target, replacement)
    logger.info(f"replace: '{source}' with '{target}' replaced by '{replacement}' -> '{result}'")
    return result

def func_add(args, line):
    if len(args) < 2:
        raise InterpreterError("add expects at least two arguments", line)
    total = 0
    for arg in args:
        if not is_number(arg):
            raise InterpreterError("add expects numeric arguments", line)
        total += arg
    total = round(total, 4) if isinstance(total, float) else total
    logger.info(f"add: sum({args}) = {total}")
    return total

def func_subtract(args, line):
    if len(args) != 2:
        raise InterpreterError("subtract expects exactly two arguments", line)
    a, b = args
    if not is_number(a) or not is_number(b):
        raise InterpreterError("subtract expects numeric arguments", line)
    result = a - b
    result = round(result, 4) if isinstance(result, float) else result
    logger.info(f"subtract: {a} - {b} = {result}")
    return result

def func_multiply(args, line):
    if len(args) < 2:
        raise InterpreterError("multiply expects at least two arguments", line)
    result = 1
    for arg in args:
        if not is_number(arg):
            raise InterpreterError("multiply expects numeric arguments", line)
        result *= arg
    result = round(result, 4) if isinstance(result, float) else result
    logger.info(f"multiply: product({args}) = {result}")
    return result

def func_divide(args, line):
    if len(args) != 2:
        raise InterpreterError("divide expects exactly two arguments", line)
    dividend, divisor = args
    if not is_number(dividend) or not is_number(divisor):
        raise InterpreterError("divide expects numeric arguments", line)
    if divisor == 0:
        raise InterpreterError("Division by zero", line)
    if isinstance(dividend, int) and isinstance(divisor, int):
        result = dividend // divisor
    else:
        result = round(dividend / divisor, 4)
    logger.info(f"divide: {dividend} / {divisor} = {result}")
    return result

def func_abs(args, line):
    if len(args) != 1:
        raise InterpreterError("abs expects exactly one argument", line)
    a = args[0]
    if not is_number(a):
        raise InterpreterError("abs expects a numeric argument", line)
    result = abs(a)
    logger.info(f"abs: abs({a}) = {result}")
    return result

def func_max(args, line):
    if len(args) < 1:
        raise InterpreterError("max expects at least one argument", line)
    if not all(is_number(arg) for arg in args):
        raise InterpreterError("max expects numeric arguments", line)
    result = max(args)
    logger.info(f"max: max({args}) = {result}")
    return result

def func_min(args, line):
    if len(args) < 1:
        raise InterpreterError("min expects at least one argument", line)
    if not all(is_number(arg) for arg in args):
        raise InterpreterError("min expects numeric arguments", line)
    result = min(args)
    logger.info(f"min: min({args}) = {result}")
    return result

def func_gt(args, line):
    if len(args) != 2:
        raise InterpreterError("gt expects exactly two arguments", line)
    a, b = args
    if not is_number(a) or not is_number(b):
        raise InterpreterError("gt expects numeric arguments", line)
    result = a > b
    logger.info(f"gt: {a} > {b} = {result}")
    return result

def func_lt(args, line):
    if len(args) != 2:
        raise InterpreterError("lt expects exactly two arguments", line)
    a, b = args
    if not is_number(a) or not is_number(b):
        raise InterpreterError("lt expects numeric arguments", line)
    result = a < b
    logger.info(f"lt: {a} < {b} = {result}")
    return result

def func_equal(args, line):
    if len(args) != 2:
        raise InterpreterError("equal expects exactly two arguments", line)
    a, b = args
    result = a == b
    logger.info(f"equal: {a} == {b} = {result}")
    return result

def func_not_equal(args, line):
    if len(args) != 2:
        raise InterpreterError("not_equal expects exactly two arguments", line)
    a, b = args
    result = a != b
    logger.info(f"not_equal: {a} != {b} = {result}")
    return result

def func_str(args, line):
    if len(args) != 1:
        raise InterpreterError("str expects exactly one argument", line)
    a = args[0]
    try:
        result = convert_str(a)
        logger.info(f"str: {a} -> '{result}'")
        return result
    except ValueError:
        raise InterpreterError("str cannot convert the given type", line)

# Mapping of function names to their implementations
FUNCTIONS = {
    "puts": func_puts,
    "set": func_set,
    "concat": func_concat,
    "substring": func_substring,
    "lowercase": func_lowercase,
    "uppercase": func_uppercase,
    "replace": func_replace,
    "add": func_add,
    "subtract": func_subtract,
    "multiply": func_multiply,
    "divide": func_divide,
    "abs": func_abs,
    "max": func_max,
    "min": func_min,
    "gt": func_gt,
    "lt": func_lt,
    "equal": func_equal,
    "not_equal": func_not_equal,
    "str": func_str,
}

# Parser and evaluator
def parse_expression(expression, line):
    tokens = tokenize(expression)
    if not tokens:
        raise InterpreterError("Empty expression", line)
    return parse_tokens(tokens, line)

def tokenize(expression):
    tokens = TOKEN_REGEX.findall(expression)
    tokens = [tok for group in tokens for tok in group if tok]
    logger.debug(f"Tokenized expression: {tokens}")
    return tokens

def parse_tokens(tokens, line):
    if not tokens:
        raise InterpreterError("Unexpected end of expression", line)
    token = tokens.pop(0)
    if token == '(':
        lst = []
        while tokens and tokens[0] != ')':
            lst.append(parse_tokens(tokens, line))
        if not tokens:
            raise InterpreterError("Expected ')'", line)
        tokens.pop(0)  # Remove ')'
        logger.debug(f"Parsed list: {lst}")
        return lst
    elif token == ')':
        raise InterpreterError("Unexpected ')'", line)
    else:
        return atom(token, line)

def atom(token, line):
    if token.startswith('"') and token.endswith('"'):
        value = token[1:-1]
        logger.debug(f"Atom: String '{value}'")
        return value
    elif token == "true":
        logger.debug("Atom: Boolean True")
        return True
    elif token == "false":
        logger.debug("Atom: Boolean False")
        return False
    elif token == "null":
        logger.debug("Atom: Null")
        return None
    else:
        # Try to parse as integer or float
        try:
            if '.' in token:
                value = float(token)
                logger.debug(f"Atom: Float {value}")
                return value
            else:
                value = int(token)
                logger.debug(f"Atom: Integer {value}")
                return value
        except ValueError:
            # It's a variable name
            if token in symbols:
                value = symbols[token]
                logger.debug(f"Atom: Variable '{token}' with value '{value}'")
                return value
            else:
                logger.debug(f"Atom: Undefined variable or function '{token}'")
                return token  # Could be a function name

def evaluate(ast, line):
    if isinstance(ast, list):
        if not ast:
            raise InterpreterError("Empty expression", line)
        func_name = ast[0]
        if not isinstance(func_name, str):
            raise InterpreterError("Function name must be a string", line)
        if func_name not in FUNCTIONS:
            raise InterpreterError(f"Undefined function '{func_name}'", line)
        func = FUNCTIONS[func_name]
        args = []
        for arg in ast[1:]:
            args.append(evaluate(arg, line))
        logger.debug(f"Evaluating function '{func_name}' with arguments {args}")
        return func(args, line)
    else:
        logger.debug(f"Returning atom: {ast}")
        return ast

@app.route('/lisp-parser', methods=['POST'])
def lisp_parser():
    global symbols, output
    symbols = {}
    output = []
    data = request.get_json()
    expressions = data.get("expressions", [])
    logger.info(f"Received expressions: {expressions}")
    for idx, expr in enumerate(expressions):
        line = idx + 1
        logger.info(f"Processing line {line}: {expr}")
        try:
            ast = parse_expression(expr, line)
            logger.debug(f"AST for line {line}: {ast}")
            result = evaluate(ast, line)
            logger.debug(f"Result for line {line}: {result}")
            # If the result is a boolean or number and not part of 'puts', it's ignored
        except InterpreterError as e:
            error_message = f"ERROR at line {e.line}"
            logger.error(error_message)
            output.append(error_message)
            break
        except Exception as e:
            error_message = f"ERROR at line {line}"
            logger.error(f"{error_message}: {str(e)}")
            output.append(error_message)
            break
    logger.info(f"Final output: {output}")
    return jsonify({"output": output})