from PySide2.QtGui import *
from PySide2.QtWidgets import QTextBrowser
from PySide2.QtCore import Qt


class LineNumberWidget(QTextBrowser):
    def __init__(self, widget):
        super().__init__()
        self.__initUi(widget)

    def __initUi(self, widget):
        self.__lineCount = widget.document().lineCount()
        self.__size = int(widget.font().pointSizeF())
        self.__styleInit()

        self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.setTextInteractionFlags(Qt.NoTextInteraction)

        self.verticalScrollBar().setEnabled(False)

        widget.verticalScrollBar().valueChanged.connect(self.__changeLineWidgetScrollAsTargetedWidgetScrollChanged)

        self.__initLineCount()
        self.befor_hightlight_line = None

    def __changeLineWidgetScrollAsTargetedWidgetScrollChanged(self, v):
        self.verticalScrollBar().setValue(v)
        self.setWidthByStr()

    def __initLineCount(self):
        for n in range(1, self.__lineCount+1):
            self.append(str(n))

    def changeLineCount(self, n):
        max_one = max(self.__lineCount, n)
        diff = n-self.__lineCount
        if max_one == self.__lineCount:
            first_v = self.verticalScrollBar().value()
            for i in range(self.__lineCount, self.__lineCount + diff, -1):
                self.moveCursor(QTextCursor.End, QTextCursor.MoveAnchor)
                self.moveCursor(QTextCursor.StartOfLine, QTextCursor.MoveAnchor)
                self.moveCursor(QTextCursor.End, QTextCursor.KeepAnchor)
                self.textCursor().removeSelectedText()
                self.textCursor().deletePreviousChar()
            last_v = self.verticalScrollBar().value()
            if abs(first_v-last_v) != 2:
                self.verticalScrollBar().setValue(first_v)
        else:
            for i in range(self.__lineCount, self.__lineCount + diff, 1):
                self.append(str(i + 1))

        self.__lineCount = n

    def selectLine(self, line):
        position = self.document().findBlockByLineNumber(line-1).position()
        tc = self.textCursor()
        tc.setPosition(position, QTextCursor.MoveAnchor) # 直接跳转到start_pos
        tc.movePosition(QTextCursor.EndOfLine, QTextCursor.KeepAnchor)
        return tc
    
    def highlightLineNumber(self, line):
        if self.befor_hightlight_line:
            self.clearHighlightLineNumber(self.befor_hightlight_line)
        fmt = QTextCharFormat()
        fmt.setFontWeight(QFont.Bold)
        fmt.setForeground(QBrush(QColor(0,0,0)))
        tc = self.selectLine(line)
        tc.mergeCharFormat(fmt) # 格式化选中文本
        tc.clearSelection() # 取消选中
        self.befor_hightlight_line = line
    
    def clearHighlightLineNumber(self, line):
        tc = self.selectLine(line)
        tc.setCharFormat(QTextCharFormat())
    
    def setValue(self, v):
        self.verticalScrollBar().setValue(v)
        
    def setFontSize(self, s: float):
        self.__size = int(s)
        self.__styleInit()
    
    def setWidthByStr(self):
        withd = (len(str(self.__lineCount)) + 2) * self.__size*0.7
        self.setFixedWidth(withd)
    
    def line_count(self):
        return self.__lineCount
        
    def __styleInit(self):
        self.__style = f'''
                       QTextBrowser 
                       {{ 
                       background: transparent; 
                       border: none; 
                       color: #AAA; 
                       font: {self.__size}pt;
                       }}
                       '''
        
        self.setStyleSheet(self.__style)
        self.setWidthByStr()