#!/usr/bin/env python
# encoding: utf-8

"""Base classes for all text objects."""

from UltiSnips import _vim
from UltiSnips.position import Position

def _calc_end(text, start):
    """Calculate the end position of the 'text' starting at 'start."""
    if len(text) == 1:
        new_end = start + Position(0, len(text[0]))
    else:
        new_end = Position(start.line + len(text)-1, len(text[-1]))
    return new_end

def _text_to_vim(start, end, text):
    """Copy the given text to the current buffer, overwriting the span 'start'
    to 'end'."""
    lines = text.split('\n')

    new_end = _calc_end(lines, start)

    before = _vim.buf[start.line][:start.col]
    after = _vim.buf[end.line][end.col:]

    new_lines = []
    if len(lines):
        new_lines.append(before + lines[0])
        new_lines.extend(lines[1:])
        new_lines[-1] += after
    _vim.buf[start.line:end.line + 1] = new_lines

    # Open any folds this might have created
    _vim.buf.cursor = start
    _vim.command("normal! zv")

    return new_end

# These classes use their subclasses a lot and we really do not want to expose
# their functions more globally.
# pylint: disable=protected-access
class TextObject(object):
    """Represents any object in the text that has a span in any ways."""

    def __init__(self, parent, token, end=None,
            initial_text="", tiebreaker=None):
        self._parent = parent

        if end is not None: # Took 4 arguments
            self._start = token
            self._end = end
            self._initial_text = initial_text
        else: # Initialize from token
            self._start = token.start
            self._end = token.end
            self._initial_text = token.initial_text
        self._tiebreaker = tiebreaker or Position(
                self._start.line, self._end.line)
        if parent is not None:
            parent._add_child(self)

    def _move(self, pivot, diff):
        """Move this object by 'diff' while 'pivot' is the point of change."""
        self._start.move(pivot, diff)
        self._end.move(pivot, diff)

    def __lt__(self, other):
        me_tuple = (self.start.line, self.start.col,
                self._tiebreaker.line, self._tiebreaker.col)
        other_tuple = (other._start.line, other._start.col,
                other._tiebreaker.line, other._tiebreaker.col)
        return me_tuple < other_tuple

    def __le__(self, other):
        me_tuple = (self._start.line, self._start.col,
                self._tiebreaker.line, self._tiebreaker.col)
        other_tuple = (other._start.line, other._start.col,
                other._tiebreaker.line, other._tiebreaker.col)
        return me_tuple <= other_tuple

    def __repr__(self):
        ct = ""
        try:
            ct = self.current_text
        except IndexError:
            ct = "<err>"

        return "%s(%r->%r,%r)" % (self.__class__.__name__,
                self._start, self._end, ct)

    @property
    def current_text(self):
        """The current text of this object."""
        if self._start.line == self._end.line:
            return _vim.buf[self._start.line][self._start.col:self._end.col]
        else:
            lines = [_vim.buf[self._start.line][self._start.col:]]
            lines.extend(_vim.buf[self._start.line+1:self._end.line])
            lines.append(_vim.buf[self._end.line][:self._end.col])
            return '\n'.join(lines)

    @property
    def start(self):
        """The start position."""
        return self._start

    @property
    def end(self):
        """The end position."""
        return self._end

    def overwrite(self, gtext=None):
        """Overwrite the text of this object in the Vim Buffer and update its
        length information. If 'gtext' is None use the initial text of this
        object.
        """
        # We explicitly do not want to move our children around here as we
        # either have non or we are replacing text initially which means we do
        # not want to mess with their positions
        if self.current_text == gtext:
            return
        old_end = self._end
        self._end = _text_to_vim(
                self._start, self._end, gtext or self._initial_text)
        if self._parent:
            self._parent._child_has_moved(
                self._parent._children.index(self), min(old_end, self._end),
                self._end.delta(old_end)
            )

    def _update(self, done):
        """Update this object inside the Vim Buffer.

        Return False if you need to be called again for this edit cycle.
        Otherwise return True.
        """
        raise NotImplementedError("Must be implemented by subclasses.")

class EditableTextObject(TextObject):
    """
    This base class represents any object in the text
    that can be changed by the user
    """
    def __init__(self, *args, **kwargs):
        TextObject.__init__(self, *args, **kwargs)
        self._children = []
        self._tabstops = {}

    ##############
    # Properties #
    ##############
    @property
    def children(self):
        """List of all children."""
        return self._children

    @property
    def _editable_children(self):
        """List of all children that are EditableTextObjects"""
        return [child for child in self._children if
                isinstance(child, EditableTextObject)]

    ####################
    # Public Functions #
    ####################
    def find_parent_for_new_to(self, pos):
        """Figure out the parent object for something at 'pos'."""
        for children in self._editable_children:
            if children._start <= pos < children._end:
                return children.find_parent_for_new_to(pos)
        return self

    ###############################
    # Private/Protected functions #
    ###############################
    def _do_edit(self, cmd):
        """Apply the edit 'cmd' to this object."""
        ctype, line, col, text = cmd
        assert ('\n' not in text) or (text == "\n")
        pos = Position(line, col)

        to_kill = set()
        new_cmds = []
        for child in self._children:
            if ctype == "I": # Insertion
                if (child._start < pos <
                        Position(child._end.line, child._end.col) and
                        isinstance(child, NoneditableTextObject)):
                    to_kill.add(child)
                    new_cmds.append(cmd)
                    break
                elif ((child._start <= pos <= child._end) and
                        isinstance(child, EditableTextObject)):
                    child._do_edit(cmd)
                    return
            else: # Deletion
                delend = pos + Position(0, len(text)) if text != "\n" \
                        else Position(line + 1, 0)
                if ((child._start <= pos < child._end) and
                        (child._start < delend <= child._end)):
                    # this edit command is completely for the child
                    if isinstance(child, NoneditableTextObject):
                        to_kill.add(child)
                        new_cmds.append(cmd)
                        break
                    else:
                        child._do_edit(cmd)
                        return
                elif ((pos < child._start and child._end <= delend) or
                        (pos <= child._start and child._end < delend)):
                    # Case: this deletion removes the child
                    to_kill.add(child)
                    new_cmds.append(cmd)
                    break
                elif (pos < child._start and
                        (child._start < delend <= child._end)):
                    # Case: partially for us, partially for the child
                    my_text = text[:(child._start-pos).col]
                    c_text = text[(child._start-pos).col:]
                    new_cmds.append((ctype, line, col, my_text))
                    new_cmds.append((ctype, line, col, c_text))
                    break
                elif (delend >= child._end and (
                        child._start <= pos < child._end)):
                    # Case: partially for us, partially for the child
                    c_text = text[(child._end-pos).col:]
                    my_text = text[:(child._end-pos).col]
                    new_cmds.append((ctype, line, col, c_text))
                    new_cmds.append((ctype, line, col, my_text))
                    break

        for child in to_kill:
            self._del_child(child)
        if len(new_cmds):
            for child in new_cmds:
                self._do_edit(child)
            return

        # We have to handle this ourselves
        delta = Position(1, 0) if text == "\n" else Position(0, len(text))
        if ctype == "D":
             # Makes no sense to delete in empty textobject
            if self._start == self._end:
                return
            delta.line *= -1
            delta.col *= -1
        pivot = Position(line, col)
        idx = -1
        for cidx, child in enumerate(self._children):
            if child._start < pivot <= child._end:
                idx = cidx
        self._child_has_moved(idx, pivot, delta)

    def _move(self, pivot, diff):
        TextObject._move(self, pivot, diff)

        for child in self._children:
            child._move(pivot, diff)

    def _child_has_moved(self, idx, pivot, diff):
        """Called when a the child with 'idx' has moved behind 'pivot' by
        'diff'."""
        self._end.move(pivot, diff)

        for child in self._children[idx+1:]:
            child._move(pivot, diff)

        if self._parent:
            self._parent._child_has_moved(
                self._parent._children.index(self), pivot, diff
            )

    def _get_next_tab(self, number):
        """Returns the next tabstop after 'number'."""
        if not len(self._tabstops.keys()):
            return
        tno_max = max(self._tabstops.keys())

        possible_sol = []
        i = number + 1
        while i <= tno_max:
            if i in self._tabstops:
                possible_sol.append((i, self._tabstops[i]))
                break
            i += 1

        child = [c._get_next_tab(number) for c in self._editable_children]
        child = [c for c in child if c]

        possible_sol += child

        if not len(possible_sol):
            return None

        return min(possible_sol)


    def _get_prev_tab(self, number):
        """Returns the previous tabstop before 'number'."""
        if not len(self._tabstops.keys()):
            return
        tno_min = min(self._tabstops.keys())

        possible_sol = []
        i = number - 1
        while i >= tno_min and i > 0:
            if i in self._tabstops:
                possible_sol.append((i, self._tabstops[i]))
                break
            i -= 1

        child = [c._get_prev_tab(number) for c in self._editable_children]
        child = [c for c in child if c]

        possible_sol += child

        if not len(possible_sol):
            return None

        return max(possible_sol)

    def _get_tabstop(self, requester, number):
        """Returns the tabstop 'number'. 'requester' is the class that is
        interested in this."""
        if number in self._tabstops:
            return self._tabstops[number]
        for child in self._editable_children:
            if child is requester:
                continue
            rv = child._get_tabstop(self, number)
            if rv is not None:
                return rv
        if self._parent and requester is not self._parent:
            return self._parent._get_tabstop(self, number)

    def _update(self, done):
        if all((child in done) for child in self._children):
            assert self not in done
            done.add(self)
        return True

    def _add_child(self, child):
        """Add 'child' as a new child of this text object."""
        self._children.append(child)
        self._children.sort()

    def _del_child(self, child):
        """Delete this 'child'."""
        child._parent = None
        self._children.remove(child)

        # If this is a tabstop, delete it
        try:
            del self._tabstops[child.number]
        except AttributeError:
            pass

class NoneditableTextObject(TextObject):
    """All passive text objects that the user can't edit by hand."""
    def _update(self, done):
        return True
