#!/usr/bin/env python
# vim:ts=4:sw=4:et:

# ----------------------------------------------------------------------
# Copyleft (K), Jose M. Rodriguez-Rosa (a.k.a. Boriel)
#
# This program is Free Software and is released under the terms of
#                    the GNU General License
# ----------------------------------------------------------------------


from src.api import config, errmsg, global_
from src.api.constants import CLASS, SCOPE
from src.symbols import sym as symbols
from src.symbols.symbol_ import Symbol
from src.symbols.type_ import Type

__all__ = [
    "check_type",
    "check_is_declared_explicit",
    "check_and_make_label",
    "check_type_is_explicit",
    "check_call_arguments",
    "check_pending_calls",
    "check_pending_labels",
    "is_number",
    "is_const",
    "is_static",
    "is_string",
    "is_numeric",
    "is_dynamic",
    "is_null",
    "is_unsigned",
    "common_type",
]


# ----------------------------------------------------------------------
# Several check functions.
# These functions trigger syntax errors if checking goal fails.
# ----------------------------------------------------------------------


def check_type(lineno, type_list, arg):
    """Check arg's type is one in type_list, otherwise,
    raises an error.
    """
    if not isinstance(type_list, list):
        type_list = [type_list]

    if arg.type_ in type_list:
        return True

    if len(type_list) == 1:
        errmsg.error(lineno, "Wrong expression type '%s'. Expected '%s'" % (arg.type_, type_list[0]))
    else:
        errmsg.error(lineno, "Wrong expression type '%s'. Expected one of '%s'" % (arg.type_, tuple(type_list)))

    return False


def check_is_declared_explicit(lineno: int, id_: str, classname: str = "variable") -> bool:
    """Check if the current ID is already declared.
    If not, triggers a "undeclared identifier" error,
    if the --explicit command line flag is enabled (or #pragma
    option strict is in use).

    If not in strict mode, passes it silently.
    """
    if not config.OPTIONS.explicit:
        return True

    return global_.SYMBOL_TABLE.check_is_declared(id_, lineno, classname)


def check_is_callable(lineno: int, id_: str) -> bool:
    entry = global_.SYMBOL_TABLE.get_entry(id_)
    if entry is None:
        return False

    if entry.class_ not in (CLASS.function, CLASS.sub):
        errmsg.syntax_error_unexpected_class(lineno, id_, entry.class_, CLASS.function)
        return False

    return True


def check_type_is_explicit(lineno: int, id_: str, type_):
    assert isinstance(type_, symbols.TYPE)
    if type_.implicit:
        if config.OPTIONS.strict:
            errmsg.syntax_error_undeclared_type(lineno, id_)


def check_call_arguments(lineno: int, id_: str, args):
    """Check arguments against function signature.

    Checks every argument in a function call against a function.
    Returns True on success.
    """
    if not global_.SYMBOL_TABLE.check_is_declared(id_, lineno, "function"):
        return False

    if not check_is_callable(lineno, id_):
        return False

    entry = global_.SYMBOL_TABLE.get_entry(id_)
    named_args: dict[str, symbols.ARGUMENT] = {}

    param_names = {x.name for x in entry.ref.params}
    for arg in args:
        if arg.name is not None and arg.name not in param_names:
            errmsg.error(lineno, f"Unexpected argument '{arg.name}'", fname=entry.filename)
            return False

    last_arg_name = None
    for arg, param in zip(args, entry.ref.params):
        if last_arg_name is not None and arg.name is None:
            errmsg.error(
                lineno, f"Positional argument cannot go after keyword argument '{last_arg_name}'", fname=entry.filename
            )
            return False

        if arg.name is not None:
            last_arg_name = arg.name
        else:
            arg.name = param.name

        named_args[arg.name] = arg

    if len(named_args) < len(entry.ref.params):  # try filling default params
        for param in entry.ref.params:
            if param.name in named_args:
                continue
            if param.default_value is None:
                break
            arg = symbols.ARGUMENT(param.default_value, lineno=lineno, byref=False, name=param.name)
            symbols.ARGLIST.make_node(args, arg)
            named_args[arg.name] = arg

    for arg in args:
        if arg.name is None:
            errmsg.error(lineno, f"Too many arguments for Function '{id_}'", fname=entry.filename)
            return False

    if len(named_args) != len(entry.ref.params):
        c = "s" if len(entry.ref.params) != 1 else ""
        errmsg.error(
            lineno,
            f"Function '{id_}' takes {len(entry.ref.params)} parameter{c}, not {len(args)}",
            fname=entry.filename,
        )
        return False

    for param in entry.ref.params:
        arg = named_args[param.name]

        if arg.class_ in (CLASS.var, CLASS.array) and param.class_ != arg.class_:
            errmsg.error(lineno, f"Invalid argument '{arg.value}'", fname=arg.filename)
            return None

        if not arg.typecast(param.type_):
            return False

        if param.byref:
            if not isinstance(arg.value, symbols.ID):
                errmsg.error(
                    lineno, "Expected a variable name, not an expression (parameter By Reference)", fname=arg.filename
                )
                return False

            if arg.class_ not in (CLASS.var, CLASS.array):
                errmsg.error(lineno, "Expected a variable or array name (parameter By Reference)")
                return False

            arg.byref = True

        if arg.value is not None:
            arg.value.add_required_symbol(param)

    if entry.forwarded:  # The function / sub was DECLARED but not implemented
        errmsg.error(
            lineno,
            "%s '%s' declared but not implemented" % (CLASS.to_string(entry.class_), entry.name),
            fname=entry.filename,
        )
        return False

    return True


def check_pending_calls():
    """Calls the above function for each pending call of the current scope
    level
    """
    result = True

    # Check for functions defined after calls (parameters, etc)
    for id_, params, lineno in global_.FUNCTION_CALLS:
        result = result and check_call_arguments(lineno, id_, params)

    return result


def check_pending_labels(ast):
    """Iteratively traverses the node looking for ID with no class set,
    marks them as labels, and check they've been declared.

    This way we avoid stack overflow for high line-numbered listings.
    """
    result = True
    visited = set()
    pending = [ast]

    while pending:
        node = pending.pop()

        if node is None or node in visited:  # Avoid recursive infinite-loop
            continue

        visited.add(node)
        for x in node.children:
            pending.append(x)

        if node.token not in ("ID", "LABEL"):
            continue

        tmp = global_.SYMBOL_TABLE.get_entry(node.name)
        if tmp is None or tmp.class_ == CLASS.unknown:
            errmsg.error(node.lineno, f'Undeclared identifier "{node.name}"')
        else:
            assert tmp.class_ == CLASS.label

        result = result and tmp is not None

    return result


def check_and_make_label(lbl: str | int | float, lineno):
    """Checks if the given label (or line number) is valid and, if so,
    returns a label object.
    :param lbl: Line number of label (string)
    :param lineno: Line number in the basic source code for error reporting
    :return: Label object or None if error.
    """
    if isinstance(lbl, float):
        if lbl == int(lbl):
            id_ = str(int(lbl))
        else:
            errmsg.error(lineno, "Line numbers must be integers.")
            return None
    else:
        id_ = lbl

    return global_.SYMBOL_TABLE.access_label(id_, lineno)


# ----------------------------------------------------------------------
# Function for checking some arguments
# ----------------------------------------------------------------------
def is_null(*symbols_):
    """True if no nodes or all the given nodes are either
    None, NOP or empty blocks. For blocks this applies recursively
    """
    for sym in symbols_:
        if sym is None:
            continue
        if not isinstance(sym, symbols.SYMBOL):
            return False
        if sym.token == "NOP":
            continue
        if sym.token == "BLOCK":
            if not is_null(*sym.children):
                return False
            continue
        return False
    return True


def is_SYMBOL(token: str, *symbols_: symbols.SYMBOL):
    """Returns True if ALL the given argument are AST nodes
    of the given token (e.g. 'BINARY')
    """
    assert all(isinstance(x, symbols.SYMBOL) for x in symbols_)
    return all(sym.token == token for sym in symbols_)


def is_LABEL(*p):
    return is_SYMBOL("LABEL", *p)


def is_string(*p):
    """Returns True if ALL the arguments are AST nodes
    containing STRING or string CONSTANTS
    """
    return all(is_SYMBOL("STRING", x) or is_const(x) and is_type(Type.string, x) for x in p)


def is_const(*p):
    """A constant in the program, like CONST a = 5"""
    return is_SYMBOL("CONST", *p)


def is_CONST(*p):
    """Not to be confused with the above.
    Check it's a CONSTant EXPRession
    """
    return is_SYMBOL("CONSTEXPR", *p)


def is_static(*p):
    """A static value (does not change at runtime)
    which is known at compile time
    """
    return all(is_CONST(x) or is_number(x) or is_const(x) for x in p)


def is_number(*p):
    """Returns True if ALL the arguments are AST nodes
    containing NUMBER or numeric CONSTANTS
    """
    return all(isinstance(i, Symbol) and i.token in ("NUMBER", "CONST") and Type.is_numeric(i.type_) for i in p)


def is_static_str(*p):
    return all(i.token == "STRING" for i in p)


def is_var(*p):
    """Returns True if ALL the arguments are AST nodes
    containing ID
    """
    return is_SYMBOL("VAR", *p)


def is_unsigned(*p):
    """Returns false unless all types in p are unsigned"""
    try:
        return all(i.type_.is_basic and Type.is_unsigned(i.type_) for i in p)
    except Exception:
        pass

    return False


def is_signed(*p):
    """Returns false unless all types in p are signed"""
    try:
        return all(i.type_.is_basic and Type.is_signed(i.type_) for i in p)
    except Exception:
        pass

    return False


def is_numeric(*p):
    """Returns false unless all elements in p are of numerical type"""
    try:
        return all(i.type_.is_basic and Type.is_numeric(i.type_) for i in p)
    except Exception:
        pass

    return False


def is_type(type_, *p):
    """True if all args have the same type"""
    try:
        return all(i.type_ == type_ for i in p)
    except Exception:
        pass

    return False


def is_dynamic(*p):  # TODO: Explain this better
    """True if all args are dynamic (e.g. Strings, dynamic arrays, etc.)
    The use a ptr (ref) and it might change during runtime.
    """
    try:
        return not any(i.scope == SCOPE.global_ and i.is_basic and i.type_ != Type.string for i in p)
    except Exception:
        pass

    return False


def is_callable(*p):
    """True if all the args are functions and / or subroutines"""
    return all(x.token == "FUNCTION" for x in p)


def is_block_accessed(block):
    """Returns True if a block is "accessed". A block of code is accessed if
    it has a LABEL and it is used in a GOTO, GO SUB or @address access
    :param block: A block of code (AST node)
    :return: True / False depending if it has labels accessed or not
    """
    if is_LABEL(block) and block.accessed:
        return True

    return any(not is_callable(child) and is_block_accessed(child) for child in block.children)


def is_temporary_value(node) -> bool:
    """Returns if the AST node value is a variable or a temporary copy in the heap."""
    return node.token not in ("STRING", "VAR") and node.t[0] not in ("_", "#")


def common_type(a, b):
    """Returns a type which is common for both a and b types.
    Returns None if no common types allowed.
    """
    if a is None or b is None:
        return None

    if not isinstance(a, symbols.TYPE):
        a = a.type_

    if not isinstance(b, symbols.TYPE):
        b = b.type_

    if a == b:  # Both types are the same?
        return a  # Returns it

    if a == Type.unknown and b == Type.unknown:
        return symbols.BASICTYPE(global_.DEFAULT_TYPE)

    if a == Type.unknown:
        return b

    if b == Type.unknown:
        return a

    # TODO: This will removed / expanded in the future
    assert a.is_basic
    assert b.is_basic

    types = (a, b)

    if Type.float_ in types:
        return Type.float_

    if Type.fixed in types:
        return Type.fixed

    if Type.string in types:  # TODO: Check this ??
        return Type.unknown

    result = a if a.size > b.size else b

    if not Type.is_unsigned(a) or not Type.is_unsigned(b):
        result = Type.to_signed(result)

    return result


def is_ender(node) -> bool:
    """Returns whether this node ends a block, that is, the following instruction won't be
    executed after this one
    """
    return node.token in {
        "END",
        "ERROR",
        "CONTINUE_DO",
        "CONTINUE_FOR",
        "CONTINUE_WHILE",
        "EXIT_DO",
        "EXIT_FOR",
        "EXIT_WHILE",
        "GOTO",
        "RETURN",
        "STOP",
    }


def check_class(node, class_: CLASS, lineno: int) -> bool:
    """Returns whether the given node has CLASS.unknown or the given class_.
    It False, it will emit a syntax error
    """
    if node.class_ == CLASS.unknown or node.class_ == class_:
        return True

    errmsg.syntax_error_unexpected_class(lineno, node.name, node.class_, class_)
    return False
