# source: http://stackoverflow.com/questions/2758159/how-to-embed-a-python-interpreter-in-a-pyqt-widget

import sys
import os
import re
import traceback

from PyQt5 import QtCore
from PyQt5 import QtGui
from PyQt5 import QtWidgets

from electrum import util
from electrum.i18n import _

from .util import MONOSPACE_FONT


class OverlayLabel(QtWidgets.QLabel):
    STYLESHEET = '''
    QLabel, QLabel link {
        color: rgb(0, 0, 0);
        background-color: rgb(248, 240, 200);
        border: 1px solid;
        border-color: rgb(255, 114, 47);
        padding: 2px;
    }
    '''
    def __init__(self, text, parent):
        super().__init__(text, parent)
        self.setMinimumHeight(150)
        self.setGeometry(0, 0, self.width(), self.height())
        self.setStyleSheet(self.STYLESHEET)
        self.setMargin(0)
        parent.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)
        self.setWordWrap(True)

    def mousePressEvent(self, e):
        self.hide()

    def on_resize(self, w):
        padding = 2  # px, from the stylesheet above
        self.setFixedWidth(w - padding)


class Console(QtWidgets.QPlainTextEdit):
    def __init__(self, prompt='>>> ', parent=None):
        QtWidgets.QPlainTextEdit.__init__(self, parent)

        self.prompt = prompt
        self.history = []
        self.namespace = {}
        self.construct = []

        self.setGeometry(50, 75, 600, 400)
        self.setWordWrapMode(QtGui.QTextOption.WrapAnywhere)
        self.setUndoRedoEnabled(False)
        self.document().setDefaultFont(QtGui.QFont(MONOSPACE_FONT, 10, QtGui.QFont.Normal))

        self.updateNamespace({'run':self.run_script})
        self.set_json(False)

        warning_text = "<h1>{}</h1><br>{}<br><br>{}".format(
            _("Warning!"),
            _("Do not paste code here that you don't understand. Executing the wrong code could lead "
              "to your coins being irreversibly lost."),
            _("Click here to hide this message.")
        )
        self.messageOverlay = OverlayLabel(warning_text, self)

    def resizeEvent(self, e):
        super().resizeEvent(e)
        vertical_scrollbar_width = self.verticalScrollBar().width() * self.verticalScrollBar().isVisible()
        self.messageOverlay.on_resize(self.width() - vertical_scrollbar_width)

    def set_json(self, b):
        self.is_json = b

    def run_script(self, filename):
        with open(filename) as f:
            script = f.read()

        # eval is generally considered bad practice. use it wisely!
        result = eval(script, self.namespace, self.namespace)



    def updateNamespace(self, namespace):
        self.namespace.update(namespace)

    def showMessage(self, message):
        self.appendPlainText(message)
        self.newPrompt('')

    def clear(self):
        curr_line = self.getCommand()
        self.setPlainText('')
        self.newPrompt(curr_line)

    def newPrompt(self, curr_line):
        if self.construct:
            prompt = '.' * len(self.prompt)
        else:
            prompt = self.prompt

        self.completions_pos = self.textCursor().position()
        self.completions_visible = False

        self.appendPlainText(prompt)
        self.moveCursor(QtGui.QTextCursor.End)

    def getCommand(self):
        doc = self.document()
        curr_line = doc.findBlockByLineNumber(doc.lineCount() - 1).text()
        curr_line = curr_line.rstrip()
        curr_line = curr_line[len(self.prompt):]
        return curr_line

    def setCommand(self, command):
        if self.getCommand() == command:
            return

        doc = self.document()
        curr_line = doc.findBlockByLineNumber(doc.lineCount() - 1).text()
        self.moveCursor(QtGui.QTextCursor.End)
        for i in range(len(curr_line) - len(self.prompt)):
            self.moveCursor(QtGui.QTextCursor.Left, QtGui.QTextCursor.KeepAnchor)

        self.textCursor().removeSelectedText()
        self.textCursor().insertText(command)
        self.moveCursor(QtGui.QTextCursor.End)

    def show_completions(self, completions):
        if self.completions_visible:
            self.hide_completions()

        c = self.textCursor()
        c.setPosition(self.completions_pos)

        completions = map(lambda x: x.split('.')[-1], completions)
        t = '\n' + ' '.join(completions)
        if len(t) > 500:
            t = t[:500] + '...'
        c.insertText(t)
        self.completions_end = c.position()

        self.moveCursor(QtGui.QTextCursor.End)
        self.completions_visible = True

    def hide_completions(self):
        if not self.completions_visible:
            return
        c = self.textCursor()
        c.setPosition(self.completions_pos)
        l = self.completions_end - self.completions_pos
        for x in range(l): c.deleteChar()

        self.moveCursor(QtGui.QTextCursor.End)
        self.completions_visible = False

    def getConstruct(self, command):
        if self.construct:
            prev_command = self.construct[-1]
            self.construct.append(command)
            if not prev_command and not command:
                ret_val = '\n'.join(self.construct)
                self.construct = []
                return ret_val
            else:
                return ''
        else:
            if command and command[-1] == (':'):
                self.construct.append(command)
                return ''
            else:
                return command

    def getHistory(self):
        return self.history

    def setHistory(self, history):
        self.history = history

    def addToHistory(self, command):
        if command[0:1] == ' ':
            return

        if command and (not self.history or self.history[-1] != command):
            self.history.append(command)
        self.history_index = len(self.history)

    def getPrevHistoryEntry(self):
        if self.history:
            self.history_index = max(0, self.history_index - 1)
            return self.history[self.history_index]
        return ''

    def getNextHistoryEntry(self):
        if self.history:
            hist_len = len(self.history)
            self.history_index = min(hist_len, self.history_index + 1)
            if self.history_index < hist_len:
                return self.history[self.history_index]
        return ''

    def getCursorPosition(self):
        c = self.textCursor()
        return c.position() - c.block().position() - len(self.prompt)

    def setCursorPosition(self, position):
        self.moveCursor(QtGui.QTextCursor.StartOfLine)
        for i in range(len(self.prompt) + position):
            self.moveCursor(QtGui.QTextCursor.Right)

    def register_command(self, c, func):
        methods = { c: func}
        self.updateNamespace(methods)


    def runCommand(self):
        command = self.getCommand()
        self.addToHistory(command)

        command = self.getConstruct(command)

        if command:
            tmp_stdout = sys.stdout

            class stdoutProxy():
                def __init__(self, write_func):
                    self.write_func = write_func
                    self.skip = False

                def flush(self):
                    pass

                def write(self, text):
                    if not self.skip:
                        stripped_text = text.rstrip('\n')
                        self.write_func(stripped_text)
                        QtCore.QCoreApplication.processEvents()
                    self.skip = not self.skip

            if type(self.namespace.get(command)) == type(lambda:None):
                self.appendPlainText("'{}' is a function. Type '{}()' to use it in the Python console."
                                     .format(command, command))
                self.newPrompt('')
                return

            sys.stdout = stdoutProxy(self.appendPlainText)
            try:
                try:
                    # eval is generally considered bad practice. use it wisely!
                    result = eval(command, self.namespace, self.namespace)
                    if result is not None:
                        if self.is_json:
                            util.print_msg(util.json_encode(result))
                        else:
                            self.appendPlainText(repr(result))
                except SyntaxError:
                    # exec is generally considered bad practice. use it wisely!
                    exec(command, self.namespace, self.namespace)
            except SystemExit:
                self.close()
            except BaseException:
                traceback_lines = traceback.format_exc().split('\n')
                # Remove traceback mentioning this file, and a linebreak
                for i in (3,2,1,-1):
                    traceback_lines.pop(i)
                self.appendPlainText('\n'.join(traceback_lines))
            sys.stdout = tmp_stdout
        self.newPrompt('')
        self.set_json(False)


    def keyPressEvent(self, event):
        if event.key() == QtCore.Qt.Key_Tab:
            self.completions()
            return

        self.hide_completions()

        if event.key() in (QtCore.Qt.Key_Enter, QtCore.Qt.Key_Return):
            self.runCommand()
            return
        if event.key() == QtCore.Qt.Key_Home:
            self.setCursorPosition(0)
            return
        if event.key() == QtCore.Qt.Key_PageUp:
            return
        elif event.key() in (QtCore.Qt.Key_Left, QtCore.Qt.Key_Backspace):
            if self.getCursorPosition() == 0:
                return
        elif event.key() == QtCore.Qt.Key_Up:
            self.setCommand(self.getPrevHistoryEntry())
            return
        elif event.key() == QtCore.Qt.Key_Down:
            self.setCommand(self.getNextHistoryEntry())
            return
        elif event.key() == QtCore.Qt.Key_L and event.modifiers() == QtCore.Qt.ControlModifier:
            self.clear()

        super(Console, self).keyPressEvent(event)

    def completions(self):
        cmd = self.getCommand()
        # note for regex: new words start after ' ' or '(' or ')'
        lastword = re.split(r'[ ()]', cmd)[-1]
        beginning = cmd[0:-len(lastword)]

        path = lastword.split('.')
        prefix = '.'.join(path[:-1])
        prefix = (prefix + '.') if prefix else prefix
        ns = self.namespace.keys()

        if len(path) == 1:
            ns = ns
        else:
            assert len(path) > 1
            obj = self.namespace.get(path[0])
            try:
                for attr in path[1:-1]:
                    obj = getattr(obj, attr)
            except AttributeError:
                ns = []
            else:
                ns = dir(obj)

        completions = []
        for name in ns:
            if name[0] == '_':continue
            if name.startswith(path[-1]):
                completions.append(prefix+name)
        completions.sort()

        if not completions:
            self.hide_completions()
        elif len(completions) == 1:
            self.hide_completions()
            self.setCommand(beginning + completions[0])
        else:
            # find common prefix
            p = os.path.commonprefix(completions)
            if len(p)>len(lastword):
                self.hide_completions()
                self.setCommand(beginning + p)
            else:
                self.show_completions(completions)