from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import ast
import inspect
import linecache
import sys
import textwrap
import tokenize
import warnings
from ast import PyCF_ONLY_AST as _AST_FLAG
from bisect import bisect_right

import py
import six


class Source(object):
    """ an immutable object holding a source code fragment,
        possibly deindenting it.
    """

    _compilecounter = 0

    def __init__(self, *parts, **kwargs):
        self.lines = lines = []
        de = kwargs.get("deindent", True)
        for part in parts:
            if not part:
                partlines = []
            elif isinstance(part, Source):
                partlines = part.lines
            elif isinstance(part, (tuple, list)):
                partlines = [x.rstrip("\n") for x in part]
            elif isinstance(part, six.string_types):
                partlines = part.split("\n")
            else:
                partlines = getsource(part, deindent=de).lines
            if de:
                partlines = deindent(partlines)
            lines.extend(partlines)

    def __eq__(self, other):
        try:
            return self.lines == other.lines
        except AttributeError:
            if isinstance(other, str):
                return str(self) == other
            return False

    __hash__ = None

    def __getitem__(self, key):
        if isinstance(key, int):
            return self.lines[key]
        else:
            if key.step not in (None, 1):
                raise IndexError("cannot slice a Source with a step")
            newsource = Source()
            newsource.lines = self.lines[key.start : key.stop]
            return newsource

    def __len__(self):
        return len(self.lines)

    def strip(self):
        """ return new source object with trailing
            and leading blank lines removed.
        """
        start, end = 0, len(self)
        while start < end and not self.lines[start].strip():
            start += 1
        while end > start and not self.lines[end - 1].strip():
            end -= 1
        source = Source()
        source.lines[:] = self.lines[start:end]
        return source

    def putaround(self, before="", after="", indent=" " * 4):
        """ return a copy of the source object with
            'before' and 'after' wrapped around it.
        """
        before = Source(before)
        after = Source(after)
        newsource = Source()
        lines = [(indent + line) for line in self.lines]
        newsource.lines = before.lines + lines + after.lines
        return newsource

    def indent(self, indent=" " * 4):
        """ return a copy of the source object with
            all lines indented by the given indent-string.
        """
        newsource = Source()
        newsource.lines = [(indent + line) for line in self.lines]
        return newsource

    def getstatement(self, lineno):
        """ return Source statement which contains the
            given linenumber (counted from 0).
        """
        start, end = self.getstatementrange(lineno)
        return self[start:end]

    def getstatementrange(self, lineno):
        """ return (start, end) tuple which spans the minimal
            statement region which containing the given lineno.
        """
        if not (0 <= lineno < len(self)):
            raise IndexError("lineno out of range")
        ast, start, end = getstatementrange_ast(lineno, self)
        return start, end

    def deindent(self):
        """return a new source object deindented."""
        newsource = Source()
        newsource.lines[:] = deindent(self.lines)
        return newsource

    def isparseable(self, deindent=True):
        """ return True if source is parseable, heuristically
            deindenting it by default.
        """
        from parser import suite as syntax_checker

        if deindent:
            source = str(self.deindent())
        else:
            source = str(self)
        try:
            # compile(source+'\n', "x", "exec")
            syntax_checker(source + "\n")
        except KeyboardInterrupt:
            raise
        except Exception:
            return False
        else:
            return True

    def __str__(self):
        return "\n".join(self.lines)

    def compile(
        self, filename=None, mode="exec", flag=0, dont_inherit=0, _genframe=None
    ):
        """ return compiled code object. if filename is None
            invent an artificial filename which displays
            the source/line position of the caller frame.
        """
        if not filename or py.path.local(filename).check(file=0):
            if _genframe is None:
                _genframe = sys._getframe(1)  # the caller
            fn, lineno = _genframe.f_code.co_filename, _genframe.f_lineno
            base = "<%d-codegen " % self._compilecounter
            self.__class__._compilecounter += 1
            if not filename:
                filename = base + "%s:%d>" % (fn, lineno)
            else:
                filename = base + "%r %s:%d>" % (filename, fn, lineno)
        source = "\n".join(self.lines) + "\n"
        try:
            co = compile(source, filename, mode, flag)
        except SyntaxError:
            ex = sys.exc_info()[1]
            # re-represent syntax errors from parsing python strings
            msglines = self.lines[: ex.lineno]
            if ex.offset:
                msglines.append(" " * ex.offset + "^")
            msglines.append("(code was compiled probably from here: %s)" % filename)
            newex = SyntaxError("\n".join(msglines))
            newex.offset = ex.offset
            newex.lineno = ex.lineno
            newex.text = ex.text
            raise newex
        else:
            if flag & _AST_FLAG:
                return co
            lines = [(x + "\n") for x in self.lines]
            linecache.cache[filename] = (1, None, lines, filename)
            return co


#
# public API shortcut functions
#


def compile_(source, filename=None, mode="exec", flags=0, dont_inherit=0):
    """ compile the given source to a raw code object,
        and maintain an internal cache which allows later
        retrieval of the source code for the code object
        and any recursively created code objects.
    """
    if isinstance(source, ast.AST):
        # XXX should Source support having AST?
        return compile(source, filename, mode, flags, dont_inherit)
    _genframe = sys._getframe(1)  # the caller
    s = Source(source)
    co = s.compile(filename, mode, flags, _genframe=_genframe)
    return co


def getfslineno(obj):
    """ Return source location (path, lineno) for the given object.
    If the source cannot be determined return ("", -1).

    The line number is 0-based.
    """
    from .code import Code

    try:
        code = Code(obj)
    except TypeError:
        try:
            fn = inspect.getsourcefile(obj) or inspect.getfile(obj)
        except TypeError:
            return "", -1

        fspath = fn and py.path.local(fn) or None
        lineno = -1
        if fspath:
            try:
                _, lineno = findsource(obj)
            except IOError:
                pass
    else:
        fspath = code.path
        lineno = code.firstlineno
    assert isinstance(lineno, int)
    return fspath, lineno


#
# helper functions
#


def findsource(obj):
    try:
        sourcelines, lineno = inspect.findsource(obj)
    except Exception:
        return None, -1
    source = Source()
    source.lines = [line.rstrip() for line in sourcelines]
    return source, lineno


def getsource(obj, **kwargs):
    from .code import getrawcode

    obj = getrawcode(obj)
    try:
        strsrc = inspect.getsource(obj)
    except IndentationError:
        strsrc = '"Buggy python version consider upgrading, cannot get source"'
    assert isinstance(strsrc, str)
    return Source(strsrc, **kwargs)


def deindent(lines):
    return textwrap.dedent("\n".join(lines)).splitlines()


def get_statement_startend2(lineno, node):
    import ast

    # flatten all statements and except handlers into one lineno-list
    # AST's line numbers start indexing at 1
    values = []
    for x in ast.walk(node):
        if isinstance(x, (ast.stmt, ast.ExceptHandler)):
            values.append(x.lineno - 1)
            for name in ("finalbody", "orelse"):
                val = getattr(x, name, None)
                if val:
                    # treat the finally/orelse part as its own statement
                    values.append(val[0].lineno - 1 - 1)
    values.sort()
    insert_index = bisect_right(values, lineno)
    start = values[insert_index - 1]
    if insert_index >= len(values):
        end = None
    else:
        end = values[insert_index]
    return start, end


def getstatementrange_ast(lineno, source, assertion=False, astnode=None):
    if astnode is None:
        content = str(source)
        # See #4260:
        # don't produce duplicate warnings when compiling source to find ast
        with warnings.catch_warnings():
            warnings.simplefilter("ignore")
            astnode = compile(content, "source", "exec", _AST_FLAG)

    start, end = get_statement_startend2(lineno, astnode)
    # we need to correct the end:
    # - ast-parsing strips comments
    # - there might be empty lines
    # - we might have lesser indented code blocks at the end
    if end is None:
        end = len(source.lines)

    if end > start + 1:
        # make sure we don't span differently indented code blocks
        # by using the BlockFinder helper used which inspect.getsource() uses itself
        block_finder = inspect.BlockFinder()
        # if we start with an indented line, put blockfinder to "started" mode
        block_finder.started = source.lines[start][0].isspace()
        it = ((x + "\n") for x in source.lines[start:end])
        try:
            for tok in tokenize.generate_tokens(lambda: next(it)):
                block_finder.tokeneater(*tok)
        except (inspect.EndOfBlock, IndentationError):
            end = block_finder.last + start
        except Exception:
            pass

    # the end might still point to a comment or empty line, correct it
    while end:
        line = source.lines[end - 1].lstrip()
        if line.startswith("#") or not line:
            end -= 1
        else:
            break
    return astnode, start, end
