from traceback import extract_tb, format_exception_only

from PySide6.QtWidgets import QWidget, QTreeWidget, QTreeWidgetItem, QLabel
from PySide6.QtGui import QAction
from PySide6.QtCore import Qt, Slot as pyqtSlot, Signal as pyqtSignal

from ..mixins import ComponentMixin
from ..utils import layout


class TracebackTree(QTreeWidget):
    name = "Traceback Viewer"

    def __init__(self, parent):
        super(TracebackTree, self).__init__(parent)
        self.setHeaderHidden(False)
        self.setItemsExpandable(False)
        self.setRootIsDecorated(False)
        self.setContextMenuPolicy(Qt.ActionsContextMenu)

        self.setColumnCount(3)
        self.setHeaderLabels(["File", "Line", "Code"])

        self.root = self.invisibleRootItem()


class TracebackPane(QWidget, ComponentMixin):
    sigHighlightLine = pyqtSignal(int)

    def __init__(self, parent):
        super(TracebackPane, self).__init__(parent)

        self.tree = TracebackTree(self)
        self.current_exception = QLabel(self)
        self.current_exception.setStyleSheet("QLabel {color : red; }")

        layout(self, (self.current_exception, self.tree), self)

        self.tree.currentItemChanged.connect(self.handleSelection)

    @pyqtSlot(object, str)
    def addTraceback(self, exc_info, code):
        self.tree.clear()

        if exc_info:
            t, exc, tb = exc_info

            root = self.tree.root
            code = code.splitlines()
            tb = [
                t for t in extract_tb(tb) if "<string>" in t.filename
            ]  # ignore highest frames (debug, exec)

            for el in tb:
                # workaround of the traceback module
                if el.line == "":
                    line = code[el.lineno - 1].strip()
                else:
                    line = el.line

                root.addChild(QTreeWidgetItem([el.filename, str(el.lineno), line]))

            exc_name = t.__name__
            exc_msg = str(exc)
            exc_msg = exc_msg.replace("<", "&lt;").replace(">", "&gt;")  # replace <>

            self.current_exception.setText("<b>{}</b>: {}".format(exc_name, exc_msg))

            # handle the special case of a SyntaxError
            if t is SyntaxError:
                root.addChild(
                    QTreeWidgetItem(
                        [
                            exc.filename,
                            str(exc.lineno),
                            exc.text.strip() if exc.text else "",
                        ]
                    )
                )
        else:
            self.current_exception.setText("")

    @pyqtSlot(QTreeWidgetItem, QTreeWidgetItem)
    def handleSelection(self, item, *args):
        if item:
            f, line = item.data(0, 0), int(item.data(1, 0))

            if "<string>" in f:
                self.sigHighlightLine.emit(line)