# -*- coding: utf-8 -*-
#
# Copyright © 2012 Pierre Raybaut
# Licensed under the terms of the MIT License
# (see spyderlib/__init__.py for details)

"""Mix-in classes

These classes were created to be able to provide Spyder's regular text and
console widget features to an independant widget based on QTextEdit for the 
IPython console plugin.
"""

import os
import re
import sre_constants

from spyderlib.qt.QtGui import (QTextCursor, QTextDocument, QApplication,
                                QCursor)
from spyderlib.qt.QtCore import Qt, QRegExp, SIGNAL

# Local imports
from spyderlib.baseconfig import _
from spyderlib.utils import encoding, sourcecode
from spyderlib.utils.misc import get_error_match
from spyderlib.utils.dochelpers import getobj
from spyderlib.py3compat import is_text_string, to_text_string, u


HISTORY_FILENAMES = []


class BaseEditMixin(object):
    def __init__(self):
        self.eol_chars = None
        
    #------EOL characters
    def set_eol_chars(self, text):
        """Set widget end-of-line (EOL) characters from text (analyzes text)"""
        if not is_text_string(text): # testing for QString (PyQt API#1)
            text = to_text_string(text)
        eol_chars = sourcecode.get_eol_chars(text)
        if eol_chars is not None and self.eol_chars is not None:
            self.document().setModified(True)
        self.eol_chars = eol_chars
        
    def get_line_separator(self):
        """Return line separator based on current EOL mode"""
        if self.eol_chars is not None:
            return self.eol_chars
        else:
            return os.linesep

    def get_text_with_eol(self):
        """Same as 'toPlainText', replace '\n' 
        by correct end-of-line characters"""
        utext = to_text_string(self.toPlainText())
        lines = utext.splitlines()
        linesep = self.get_line_separator()
        txt = linesep.join(lines)
        if utext.endswith('\n'):
            txt += linesep
        return txt


    #------Positions, coordinates (cursor, EOF, ...)
    def get_position(self, subject):
        """Get offset in character for the given subject from the start of
           text edit area"""
        cursor = self.textCursor()
        if subject == 'cursor':
            pass
        elif subject == 'sol':
            cursor.movePosition(QTextCursor.StartOfBlock)
        elif subject == 'eol':
            cursor.movePosition(QTextCursor.EndOfBlock)
        elif subject == 'eof':
            cursor.movePosition(QTextCursor.End)
        elif subject == 'sof':
            cursor.movePosition(QTextCursor.Start)
        else:
            # Assuming that input argument was already a position
            return subject
        return cursor.position()
        
    def get_coordinates(self, position):
        position = self.get_position(position)
        cursor = self.textCursor()
        cursor.setPosition(position)
        point = self.cursorRect(cursor).center()
        return point.x(), point.y()
    
    def get_cursor_line_column(self):
        """Return cursor (line, column) numbers"""
        cursor = self.textCursor()
        return cursor.blockNumber(), cursor.columnNumber()
        
    def get_cursor_line_number(self):
        """Return cursor line number"""
        return self.textCursor().blockNumber()+1

    def set_cursor_position(self, position):
        """Set cursor position"""
        position = self.get_position(position)
        cursor = self.textCursor()
        cursor.setPosition(position)
        self.setTextCursor(cursor)
        self.ensureCursorVisible()
        
    def move_cursor(self, chars=0):
        """Move cursor to left or right (unit: characters)"""
        direction = QTextCursor.Right if chars > 0 else QTextCursor.Left
        for _i in range(abs(chars)):
            self.moveCursor(direction, QTextCursor.MoveAnchor)

    def is_cursor_on_first_line(self):
        """Return True if cursor is on the first line"""
        cursor = self.textCursor()
        cursor.movePosition(QTextCursor.StartOfBlock)
        return cursor.atStart()

    def is_cursor_on_last_line(self):
        """Return True if cursor is on the last line"""
        cursor = self.textCursor()
        cursor.movePosition(QTextCursor.EndOfBlock)
        return cursor.atEnd()

    def is_cursor_at_end(self):
        """Return True if cursor is at the end of the text"""
        return self.textCursor().atEnd()

    def is_cursor_before(self, position, char_offset=0):
        """Return True if cursor is before *position*"""
        position = self.get_position(position) + char_offset
        cursor = self.textCursor()
        cursor.movePosition(QTextCursor.End)
        if position < cursor.position():
            cursor.setPosition(position)
            return self.textCursor() < cursor
                
    def __move_cursor_anchor(self, what, direction, move_mode):
        assert what in ('character', 'word', 'line')
        if what == 'character':
            if direction == 'left':
                self.moveCursor(QTextCursor.PreviousCharacter, move_mode)
            elif direction == 'right':
                self.moveCursor(QTextCursor.NextCharacter, move_mode)
        elif what == 'word':
            if direction == 'left':
                self.moveCursor(QTextCursor.PreviousWord, move_mode)
            elif direction == 'right':
                self.moveCursor(QTextCursor.NextWord, move_mode)
        elif what == 'line':
            if direction == 'down':
                self.moveCursor(QTextCursor.NextBlock, move_mode)
            elif direction == 'up':
                self.moveCursor(QTextCursor.PreviousBlock, move_mode)
                
    def move_cursor_to_next(self, what='word', direction='left'):
        """
        Move cursor to next *what* ('word' or 'character')
        toward *direction* ('left' or 'right')
        """
        self.__move_cursor_anchor(what, direction, QTextCursor.MoveAnchor)


    #------Selection
    def clear_selection(self):
        """Clear current selection"""
        cursor = self.textCursor()
        cursor.clearSelection()
        self.setTextCursor(cursor)

    def extend_selection_to_next(self, what='word', direction='left'):
        """
        Extend selection to next *what* ('word' or 'character')
        toward *direction* ('left' or 'right')
        """
        self.__move_cursor_anchor(what, direction, QTextCursor.KeepAnchor)


    #------Text: get, set, ...
    def __select_text(self, position_from, position_to):
        position_from = self.get_position(position_from)
        position_to = self.get_position(position_to)
        cursor = self.textCursor()
        cursor.setPosition(position_from)
        cursor.setPosition(position_to, QTextCursor.KeepAnchor)
        return cursor

    def get_text_line(self, line_nb):
        """Return text line at line number *line_nb*"""
        # Taking into account the case when a file ends in an empty line,
        # since splitlines doesn't return that line as the last element
        # TODO: Make this function more efficient
        try:
            return to_text_string(self.toPlainText()).splitlines()[line_nb]
        except IndexError:
            return self.get_line_separator()
    
    def get_text(self, position_from, position_to):
        """
        Return text between *position_from* and *position_to*
        Positions may be positions or 'sol', 'eol', 'sof', 'eof' or 'cursor'
        """
        cursor = self.__select_text(position_from, position_to)
        text = to_text_string(cursor.selectedText())
        if text:
            while text.endswith("\n"):
                text = text[:-1]
            while text.endswith(u("\u2029")):
                text = text[:-1]
        return text
    
    def get_character(self, position):
        """Return character at *position*"""
        position = self.get_position(position)
        cursor = self.textCursor()
        cursor.movePosition(QTextCursor.End)
        if position < cursor.position():
            cursor.setPosition(position)
            cursor.movePosition(QTextCursor.Right,
                                QTextCursor.KeepAnchor)
            return to_text_string(cursor.selectedText())
        else:
            return ''
    
    def insert_text(self, text):
        """Insert text at cursor position"""
        if not self.isReadOnly():
            self.textCursor().insertText(text)
    
    def replace_text(self, position_from, position_to, text):
        cursor = self.__select_text(position_from, position_to)
        cursor.removeSelectedText()
        cursor.insertText(text)
        
    def remove_text(self, position_from, position_to):
        cursor = self.__select_text(position_from, position_to)
        cursor.removeSelectedText()
        
    def get_current_word(self):
        """Return current word, i.e. word at cursor position"""
        cursor = self.textCursor()

        if cursor.hasSelection():
            # Removes the selection and moves the cursor to the left side 
            # of the selection: this is required to be able to properly 
            # select the whole word under cursor (otherwise, the same word is 
            # not selected when the cursor is at the right side of it):
            cursor.setPosition(min([cursor.selectionStart(),
                                    cursor.selectionEnd()]))
        else:
            # Checks if the first character to the right is a white space
            # and if not, moves the cursor one word to the left (otherwise,
            # if the character to the left do not match the "word regexp" 
            # (see below), the word to the left of the cursor won't be 
            # selected), but only if the first character to the left is not a
            # white space too.
            def is_space(move):
                curs = self.textCursor()
                curs.movePosition(move, QTextCursor.KeepAnchor)
                return not to_text_string(curs.selectedText()).strip()
            if is_space(QTextCursor.NextCharacter):
                if is_space(QTextCursor.PreviousCharacter):
                    return
                cursor.movePosition(QTextCursor.WordLeft)

        cursor.select(QTextCursor.WordUnderCursor)
        text = to_text_string(cursor.selectedText())
        match = re.findall(r'([a-zA-Z\_]+[0-9a-zA-Z\_]*)', text)
        if match:
            return match[0]
    
    def get_current_line(self):
        """Return current line's text"""
        cursor = self.textCursor()
        cursor.select(QTextCursor.BlockUnderCursor)
        return to_text_string(cursor.selectedText())
    
    def get_current_line_to_cursor(self):
        """Return text from prompt to cursor"""
        return self.get_text(self.current_prompt_pos, 'cursor')
    
    def get_line_number_at(self, coordinates):
        """Return line number at *coordinates* (QPoint)"""
        cursor = self.cursorForPosition(coordinates)
        return cursor.blockNumber()-1
    
    def get_line_at(self, coordinates):
        """Return line at *coordinates* (QPoint)"""
        cursor = self.cursorForPosition(coordinates)
        cursor.select(QTextCursor.BlockUnderCursor)
        return to_text_string(cursor.selectedText()).replace(u('\u2029'), '')
    
    def get_word_at(self, coordinates):
        """Return word at *coordinates* (QPoint)"""
        cursor = self.cursorForPosition(coordinates)
        cursor.select(QTextCursor.WordUnderCursor)
        return to_text_string(cursor.selectedText())
    
    def get_block_indentation(self, block_nb):
        """Return line indentation (character number)"""
        text = to_text_string(self.document().findBlockByNumber(block_nb).text())
        return len(text)-len(text.lstrip())
    
    def get_selection_bounds(self):
        """Return selection bounds (block numbers)"""
        cursor = self.textCursor()
        start, end = cursor.selectionStart(), cursor.selectionEnd()
        block_start = self.document().findBlock(start)
        block_end = self.document().findBlock(end)
        return sorted([block_start.blockNumber(), block_end.blockNumber()])
        

    #------Text selection
    def has_selected_text(self):
        """Returns True if some text is selected"""
        return bool(to_text_string(self.textCursor().selectedText()))

    def get_selected_text(self):
        """
        Return text selected by current text cursor, converted in unicode
        
        Replace the unicode line separator character \u2029 by 
        the line separator characters returned by get_line_separator
        """
        return to_text_string(self.textCursor().selectedText()).replace(u("\u2029"),
                                                     self.get_line_separator())
    
    def remove_selected_text(self):
        """Delete selected text"""
        self.textCursor().removeSelectedText()
        
    def replace(self, text, pattern=None):
        """Replace selected text by *text*
        If *pattern* is not None, replacing selected text using regular
        expression text substitution"""
        cursor = self.textCursor()
        cursor.beginEditBlock()
        if pattern is not None:
            seltxt = to_text_string(cursor.selectedText())
        cursor.removeSelectedText()
        if pattern is not None:
            text = re.sub(to_text_string(pattern),
                          to_text_string(text), to_text_string(seltxt))
        cursor.insertText(text)
        cursor.endEditBlock()


    #------Find/replace
    def find_multiline_pattern(self, regexp, cursor, findflag):
        """Reimplement QTextDocument's find method
        
        Add support for *multiline* regular expressions"""
        pattern = to_text_string(regexp.pattern())
        text = to_text_string(self.toPlainText())
        try:
            regobj = re.compile(pattern)
        except sre_constants.error:
            return
        if findflag & QTextDocument.FindBackward:
            # Find backward
            offset = min([cursor.selectionEnd(), cursor.selectionStart()])
            text = text[:offset]
            matches = [_m for _m in regobj.finditer(text, 0, offset)]
            if matches:
                match = matches[-1]
            else:
                return
        else:
            # Find forward
            offset = max([cursor.selectionEnd(), cursor.selectionStart()])
            match = regobj.search(text, offset)
        if match:
            pos1, pos2 = match.span()
            fcursor = self.textCursor()
            fcursor.setPosition(pos1)
            fcursor.setPosition(pos2, QTextCursor.KeepAnchor)
            return fcursor

    def find_text(self, text, changed=True, forward=True, case=False,
                  words=False, regexp=False):
        """Find text"""
        cursor = self.textCursor()
        findflag = QTextDocument.FindFlag()
        if not forward:
            findflag = findflag | QTextDocument.FindBackward
        moves = [QTextCursor.NoMove]
        if forward:
            moves += [QTextCursor.NextWord, QTextCursor.Start]
            if changed:
                if to_text_string(cursor.selectedText()):
                    new_position = min([cursor.selectionStart(),
                                        cursor.selectionEnd()])
                    cursor.setPosition(new_position)
                else:
                    cursor.movePosition(QTextCursor.PreviousWord)
        else:
            moves += [QTextCursor.End]
        if not regexp:
            text = re.escape(to_text_string(text))
        pattern = QRegExp(r"\b%s\b" % text if words else text,
                          Qt.CaseSensitive if case else Qt.CaseInsensitive,
                          QRegExp.RegExp2)
        for move in moves:
            cursor.movePosition(move)
            if regexp and '\\n' in text:
                # Multiline regular expression
                found_cursor = self.find_multiline_pattern(pattern, cursor,
                                                           findflag)
            else:
                # Single line find: using the QTextDocument's find function,
                # probably much more efficient than ours
                found_cursor = self.document().find(pattern, cursor, findflag)
            if found_cursor is not None and not found_cursor.isNull():
                self.setTextCursor(found_cursor)
                return True
        return False


class TracebackLinksMixin(object):
    QT_CLASS = None
    
    def __init__(self):
        self.__cursor_changed = False
        self.setMouseTracking(True)
        
    #------Mouse events
    def mouseReleaseEvent(self, event):
        """Go to error"""
        self.QT_CLASS.mouseReleaseEvent(self, event)            
        text = self.get_line_at(event.pos())
        if get_error_match(text) and not self.has_selected_text():
            self.emit(SIGNAL("go_to_error(QString)"), text)

    def mouseMoveEvent(self, event):
        """Show Pointing Hand Cursor on error messages"""
        text = self.get_line_at(event.pos())
        if get_error_match(text):
            if not self.__cursor_changed:
                QApplication.setOverrideCursor(QCursor(Qt.PointingHandCursor))
                self.__cursor_changed = True
            event.accept()
            return
        if self.__cursor_changed:
            QApplication.restoreOverrideCursor()
            self.__cursor_changed = False
        self.QT_CLASS.mouseMoveEvent(self, event)
        
    def leaveEvent(self, event):
        """If cursor has not been restored yet, do it now"""
        if self.__cursor_changed:
            QApplication.restoreOverrideCursor()
            self.__cursor_changed = False
        self.QT_CLASS.leaveEvent(self, event)


class InspectObjectMixin(object):
    def __init__(self):
        self.inspector = None
        self.inspector_enabled = True
    
    def set_inspector(self, inspector):
        """Set ObjectInspector DockWidget reference"""
        self.inspector = inspector
        self.inspector.set_shell(self)

    def set_inspector_enabled(self, state):
        self.inspector_enabled = state
    
    def inspect_current_object(self):
        text = ''
        text1 = self.get_text('sol', 'cursor')
        tl1 = re.findall(r'([a-zA-Z_]+[0-9a-zA-Z_\.]*)', text1)
        if tl1 and text1.endswith(tl1[-1]):
            text += tl1[-1]
        text2 = self.get_text('cursor', 'eol')
        tl2 = re.findall(r'([0-9a-zA-Z_\.]+[0-9a-zA-Z_\.]*)', text2)
        if tl2 and text2.startswith(tl2[0]):
            text += tl2[0]
        if text:
            self.show_docstring(text, force=True)
    
    def show_docstring(self, text, call=False, force=False):
        """Show docstring or arguments"""
        text = to_text_string(text) # Useful only for ExternalShellBase
        
        insp_enabled = self.inspector_enabled or force
        if force and self.inspector is not None:
            self.inspector.dockwidget.setVisible(True)
            self.inspector.dockwidget.raise_()
        if insp_enabled and (self.inspector is not None) and \
           (self.inspector.dockwidget.isVisible()):
            # ObjectInspector widget exists and is visible
            self.inspector.set_shell(self)
            self.inspector.set_object_text(text, ignore_unknown=True)
            self.setFocus() # if inspector was not at top level, raising it to
                            # top will automatically give it focus because of
                            # the visibility_changed signal, so we must give
                            # focus back to shell
            if call and self.calltips:
                # Display argument list if this is function call
                iscallable = self.iscallable(text)
                if iscallable is not None:
                    if iscallable:
                        arglist = self.get_arglist(text)
                        if isinstance(arglist, bool):
                            arglist = []
                        if arglist:
                            self.show_calltip(_("Arguments"),
                                              arglist, '#129625')
        elif self.calltips: # inspector is not visible or link is disabled
            doc = self.get__doc__(text)
            if doc is not None:
                self.show_calltip(_("Documentation"), doc)
    
    def get_last_obj(self, last=False):
        """
        Return the last valid object on the current line
        """
        return getobj(self.get_current_line_to_cursor(), last=last)


class SaveHistoryMixin(object):
    
    INITHISTORY = None
    SEPARATOR = None
    
    def __init__(self):
        pass
    
    def add_to_history(self, command):
        """Add command to history"""
        command = to_text_string(command)
        if command in ['', '\n'] or command.startswith('Traceback'):
            return
        if command.endswith('\n'):
            command = command[:-1]
        self.histidx = None
        if len(self.history)>0 and self.history[-1] == command:
            return
        self.history.append(command)
        text = os.linesep + command
        
        # When the first entry will be written in history file,
        # the separator will be append first:
        if self.history_filename not in HISTORY_FILENAMES:
            HISTORY_FILENAMES.append(self.history_filename)
            text = self.SEPARATOR + text
        
        encoding.write(text, self.history_filename, mode='ab')
        self.emit(SIGNAL('append_to_history(QString,QString)'),
                  self.history_filename, text)
