# Copyright (c) 2013 Paul Tagliamonte <paultag@debian.org>
# Copyright (c) 2013, 2014 Bob Tolbert <bob@tolbert.org>
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the "Software"),
# to deal in the Software without restriction, including without limitation
# the rights to use, copy, modify, merge, publish, distribute, sublicense,
# and/or sell copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
# DEALINGS IN THE SOFTWARE.

from hy.compiler import hy_compile, HyTypeError
from hy.models import HyObject, replace_hy_obj
from hy.lex import tokenize, LexException
from hy.errors import HyIOError

from io import open
import re
import marshal
import struct
import imp
import sys
import ast
import os
import __future__

from hy._compat import PY3, PY34, MAGIC, builtins, long_type, wr_long
from hy._compat import string_types


def ast_compile(ast, filename, mode):
    """Compile AST.
    Like Python's compile, but with some special flags."""
    flags = (__future__.CO_FUTURE_DIVISION |
             __future__.CO_FUTURE_PRINT_FUNCTION)
    return compile(ast, filename, mode, flags)


def import_buffer_to_hst(buf):
    """Import content from buf and return a Hy AST."""
    return tokenize(buf + "\n")


def import_file_to_hst(fpath):
    """Import content from fpath and return a Hy AST."""
    try:
        with open(fpath, 'r', encoding='utf-8') as f:
            return import_buffer_to_hst(f.read())
    except IOError as e:
        raise HyIOError(e.errno, e.strerror, e.filename)


def import_buffer_to_ast(buf, module_name):
    """ Import content from buf and return a Python AST."""
    return hy_compile(import_buffer_to_hst(buf), module_name)


def import_file_to_ast(fpath, module_name):
    """Import content from fpath and return a Python AST."""
    return hy_compile(import_file_to_hst(fpath), module_name)


def import_file_to_module(module_name, fpath, loader=None):
    """Import Hy source from fpath and put it into a Python module.

    If there's an up-to-date byte-compiled version of this module, load that
    instead. Otherwise, byte-compile the module once we're done loading it, if
    we can.

    Return the module."""

    module = None

    bytecode_path = get_bytecode_path(fpath)
    try:
        source_mtime = int(os.stat(fpath).st_mtime)
        with open(bytecode_path, 'rb') as bc_f:
            # The first 4 bytes are the magic number for the version of Python
            # that compiled this bytecode.
            bytecode_magic = bc_f.read(4)
            # The next 4 bytes, interpreted as a little-endian 32-bit integer,
            # are the mtime of the corresponding source file.
            bytecode_mtime, = struct.unpack('<i', bc_f.read(4))
    except (IOError, OSError):
        pass
    else:
        if bytecode_magic == MAGIC and bytecode_mtime >= source_mtime:
            # It's a cache hit. Load the byte-compiled version.
            if PY3:
                # As of Python 3.6, imp.load_compiled still exists, but it's
                # deprecated. So let's use SourcelessFileLoader instead.
                from importlib.machinery import SourcelessFileLoader
                module = (SourcelessFileLoader(module_name, bytecode_path).
                          load_module(module_name))
            else:
                module = imp.load_compiled(module_name, bytecode_path)

    if not module:
        # It's a cache miss, so load from source.
        sys.modules[module_name] = None
        try:
            _ast = import_file_to_ast(fpath, module_name)
            module = imp.new_module(module_name)
            module.__file__ = fpath
            code = ast_compile(_ast, fpath, "exec")
            try:
                write_code_as_pyc(fpath, code)
            except (IOError, OSError):
                # We failed to save the bytecode, probably because of a
                # permissions issue. The user only asked to import the
                # file, so don't bug them about it.
                pass
            eval(code, module.__dict__)
        except (HyTypeError, LexException) as e:
            if e.source is None:
                with open(fpath, 'rt') as fp:
                    e.source = fp.read()
                e.filename = fpath
            raise
        except Exception:
            sys.modules.pop(module_name, None)
            raise
        sys.modules[module_name] = module
        module.__name__ = module_name

    module.__file__ = fpath
    if loader:
        module.__loader__ = loader
    if is_package(module_name):
        module.__path__ = []
        module.__package__ = module_name
    else:
        module.__package__ = module_name.rpartition('.')[0]

    return module


def import_buffer_to_module(module_name, buf):
    try:
        _ast = import_buffer_to_ast(buf, module_name)
        mod = imp.new_module(module_name)
        eval(ast_compile(_ast, "", "exec"), mod.__dict__)
    except (HyTypeError, LexException) as e:
        if e.source is None:
            e.source = buf
            e.filename = '<stdin>'
        raise
    return mod


def hy_eval(hytree, namespace, module_name, ast_callback=None):
    foo = HyObject()
    foo.start_line = 0
    foo.end_line = 0
    foo.start_column = 0
    foo.end_column = 0
    replace_hy_obj(hytree, foo)

    if not isinstance(module_name, string_types):
        raise HyTypeError(foo, "Module name must be a string")

    _ast, expr = hy_compile(hytree, module_name, get_expr=True)

    # Spoof the positions in the generated ast...
    for node in ast.walk(_ast):
        node.lineno = 1
        node.col_offset = 1

    for node in ast.walk(expr):
        node.lineno = 1
        node.col_offset = 1

    if ast_callback:
        ast_callback(_ast, expr)

    if not isinstance(namespace, dict):
        raise HyTypeError(foo, "Globals must be a dictionary")

    # Two-step eval: eval() the body of the exec call
    eval(ast_compile(_ast, "<eval_body>", "exec"), namespace)

    # Then eval the expression context and return that
    return eval(ast_compile(expr, "<eval>", "eval"), namespace)


def write_hy_as_pyc(fname):
    _ast = import_file_to_ast(fname,
                              os.path.basename(os.path.splitext(fname)[0]))
    code = ast_compile(_ast, fname, "exec")
    write_code_as_pyc(fname, code)


def write_code_as_pyc(fname, code):
    st = os.stat(fname)
    timestamp = long_type(st.st_mtime)

    cfile = get_bytecode_path(fname)
    try:
        os.makedirs(os.path.dirname(cfile))
    except (IOError, OSError):
        pass

    with builtins.open(cfile, 'wb') as fc:
        fc.write(MAGIC)
        wr_long(fc, timestamp)
        if PY3:
            wr_long(fc, st.st_size)
        marshal.dump(code, fc)


class MetaLoader(object):
    def __init__(self, path):
        self.path = path

    def load_module(self, fullname):
        if fullname in sys.modules:
            return sys.modules[fullname]

        if not self.path:
            return

        return import_file_to_module(fullname, self.path, self)


class MetaImporter(object):
    def find_on_path(self, fullname):
        fls = ["%s/__init__.hy", "%s.hy"]
        dirpath = "/".join(fullname.split("."))

        for pth in sys.path:
            pth = os.path.abspath(pth)
            for fp in fls:
                composed_path = fp % ("%s/%s" % (pth, dirpath))
                if os.path.exists(composed_path):
                    return composed_path

    def find_module(self, fullname, path=None):
        path = self.find_on_path(fullname)
        if path:
            return MetaLoader(path)


sys.meta_path.insert(0, MetaImporter())
sys.path.insert(0, "")


def is_package(module_name):
    mpath = os.path.join(*module_name.split("."))
    for path in map(os.path.abspath, sys.path):
        if os.path.exists(os.path.join(path, mpath, "__init__.hy")):
            return True
    return False


def get_bytecode_path(source_path):
    if PY34:
        import importlib.util
        return importlib.util.cache_from_source(source_path)
    elif hasattr(imp, "cache_from_source"):
        return imp.cache_from_source(source_path)
    else:
        # If source_path has a file extension, replace it with ".pyc".
        # Otherwise, just append ".pyc".
        d, f = os.path.split(source_path)
        return os.path.join(d, re.sub(r"(?:\.[^.]+)?\Z", ".pyc", f))