import copy
import os
import re
import shlex
from enum import IntEnum

import pyqtgraph as pg
from qgis.gui import QgsFileWidget, QgsProjectionSelectionWidget
from qgis.PyQt.QtCore import QFileInfo, QSettings, Qt
from qgis.PyQt.QtGui import QFontMetricsF, QIcon
from qgis.PyQt.QtWidgets import (QApplication, QComboBox, QDialog,
                                 QDialogButtonBox, QFrame, QHBoxLayout, QLabel,
                                 QLineEdit, QListWidget, QListWidgetItem,
                                 QMessageBox, QProgressBar, QPushButton,
                                 QSizePolicy, QSpinBox, QTabWidget,
                                 QVBoxLayout, QWidget)

from . import config  # used to pass initial settings
from .app_settings import AppSettings
from .aux_classes import BlackLine, CustomPlainTextEdit, LineHighlighter

currentDir = os.path.dirname(os.path.abspath(__file__))
resourceDir = os.path.join(currentDir, 'resources')


class ColumnBound(IntEnum):
    FROM = 0
    TO = 1


class SpsImportDialog(QDialog):
    def __init__(self, parent=None, crs=None, directory=None):
        super().__init__(parent)

        # to access the main window and its components
        self.parent = parent
        self.appSettings = parent.appSettings if parent is not None and hasattr(parent, 'appSettings') else AppSettings()
        self.crs = crs
        self.oldCrs = crs
        self.setWindowTitle('SPS Import')
        self.setMinimumWidth(750)
        self.setMinimumHeight(500)

        self.fileNames = []
        self.spsFiles = []
        self.rpsFiles = []
        self.xpsFiles = []

        # Main layout
        # --- SPS Implementation selector at the top ---
        selectorLayout = QVBoxLayout()
        selectorLayout.setAlignment(Qt.AlignmentFlag.AlignTop)                  # Top-align all children
        selectorLayout.setSpacing(4)                                            # tighten vertical gaps, including label→list

        labelStyle = 'font-family: Arial; font-weight: bold; font-size: 15px;'

        filesLabel = QLabel('Select SPS files to import:')
        filesLabel.setStyleSheet(labelStyle)
        selectorLayout.addWidget(filesLabel)

        nameFilter = (
            'SPS triplets (*.s01 *.r01 *.x01);;'
            'SPS triplets (*.sps *.rps *.xps);;'
            'Source   files (*.sps *.s01 *.sp1);;'
            'Receiver files (*.rps *.r01 *.rp1);;'
            'Relation files (*.xps *.x01 *.xp1);;'
            'All files (*.*)'
        )  # file extensions

        spsFilesWidget = QgsFileWidget()
        if directory and os.path.isdir(directory):
            spsFilesWidget.setDefaultRoot(directory)
        spsFilesWidget.setStorageMode(QgsFileWidget.GetMultipleFiles)
        spsFilesWidget.setFilter(nameFilter)
        spsFilesWidget.fileChanged.connect(self.onSpsFilesChanged)

        selectorLayout.addWidget(spsFilesWidget)

        # SPS file input fields
        spsLabel = QLabel('SPS files')
        spsLabel.setMaximumWidth(80)  # Fixed width for label
        self.spsEdit = QLineEdit()
        self.spsEdit.setSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Fixed)  # Take remaining horizontal space

        spsLayout = QHBoxLayout()
        spsLayout.addWidget(spsLabel)
        spsLayout.addWidget(self.spsEdit)
        selectorLayout.addLayout(spsLayout)

        # XPS file input fields
        xpsLabel = QLabel('XPS files')
        xpsLabel.setMaximumWidth(80)  # Fixed width for label
        self.xpsEdit = QLineEdit()
        self.xpsEdit.setSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Fixed)  # Take remaining horizontal space

        xpsLayout = QHBoxLayout()
        xpsLayout.addWidget(xpsLabel)
        xpsLayout.addWidget(self.xpsEdit)
        selectorLayout.addLayout(xpsLayout)

        # RPS file input fields
        rpsLabel = QLabel('RPS files')
        rpsLabel.setMaximumWidth(80)  # Fixed width for label
        self.rpsEdit = QLineEdit()
        self.rpsEdit.setSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Fixed)  # Take remaining horizontal space

        rpsLayout = QHBoxLayout()
        rpsLayout.addWidget(rpsLabel)
        rpsLayout.addWidget(self.rpsEdit)
        selectorLayout.addLayout(rpsLayout)

        line1 = BlackLine()
        selectorLayout.addWidget(line1)
        selectorLayout.addWidget(QLabel(''))                                    # spacer

        crsLabel = QLabel('Select SPS CRS projection:')
        crsLabel.setStyleSheet(labelStyle)
        selectorLayout.addWidget(crsLabel)

        self.crsWidget = QgsProjectionSelectionWidget()
        self.crsWidget.setCrs(self.crs)
        self.crsWidget.crsChanged.connect(self.onCrsChanged)

        selectorLayout.addWidget(self.crsWidget)

        line2 = BlackLine()
        selectorLayout.addWidget(line2)
        selectorLayout.addWidget(QLabel(''))                                    # spacer

        selectorLabel = QLabel('Select SPS Format Implementation:')
        selectorLabel.setStyleSheet(labelStyle)
        selectorLayout.addWidget(selectorLabel)

        # List widget (editable, min 4 rows visible)
        # Alternatively an editable QComboBox can be used. See: https://www.pythonguis.com/docs/qcombobox/
        self.enforceUniqueName = True

        self.spsFormatListInitializing = True
        self.spsFormatList = QListWidget()
        self.spsFormatList.itemChanged.connect(self.ensureUniqueSpsName)
        self.spsFormatList.currentRowChanged.connect(self.onSpsFormatChanged)

        self.spsFormatList.setFrameShape(QFrame.Shape.Panel)
        self.spsFormatList.setFrameShadow(QFrame.Shadow.Sunken)
        self.spsFormatList.setLineWidth(1)
        self.spsFormatList.setMidLineWidth(0)
        self.spsFormatList.setSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Fixed)

        # Calculate height for exactly 4 visible rows based on font metrics
        fontMetrics = QFontMetricsF(self.spsFormatList.font())
        itemHeight = fontMetrics.height() + 4                                 # Add padding per item
        visibleRows = 4
        listHeight = int(itemHeight * visibleRows) + 4                       # Add 4 for widget borders
        self.spsFormatList.setFixedHeight(listHeight)

        self.populateSpsFormatList()

        formatLayout = QHBoxLayout()
        formatLayout.setAlignment(Qt.AlignmentFlag.AlignTop)                    # Force top alignment

        # Add list widget and buttonLayout
        formatWidget = QWidget()
        formatWidget.setLayout(formatLayout)
        formatWidget.setSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Fixed)
        # formatWidget.setFixedHeight(listHeight)                                # or listHeight + button margins

        selectorLayout.addWidget(formatWidget, 0, Qt.AlignmentFlag.AlignTop)

        # Buttons for add/remove
        buttonLayout = QVBoxLayout()
        # buttonLayout.addSpacing(20)  # spacer before the buttons

        self.addButton = QPushButton()
        self.addButton.setIcon(QIcon(os.path.join(resourceDir, 'symbologyAdd.svg')))
        self.addButton.setMaximumWidth(30)
        self.addButton.setToolTip("Add a new SPS implementation to the list, based on the current selection")

        self.addButton.clicked.connect(self.onAddSpsName)
        buttonLayout.addWidget(self.addButton)

        self.removeButton = QPushButton()
        self.removeButton.setIcon(QIcon(os.path.join(resourceDir, 'symbologyRemove.svg')))
        self.removeButton.setMaximumWidth(30)
        self.removeButton.setToolTip("Remove the selected SPS implementation from the list")
        self.removeButton.clicked.connect(self.onRemoveSpsName)
        buttonLayout.addWidget(self.removeButton)
        buttonLayout.addStretch()

        formatLayout.addWidget(self.spsFormatList)
        formatLayout.addLayout(buttonLayout)
        formatLayout.addStretch()

        self.databaseButton = QPushButton('  Reset SPS database  ')
        self.databaseButton.setToolTip("Reset the SPS implementation database to to the built-in defaults")
        self.databaseButton.setStyleSheet(labelStyle)
        self.databaseButton.setMinimumHeight(28)
        self.databaseButton.setMaximumWidth(220)
        self.databaseButton.clicked.connect(self.onResetSpsDatabase)

        dbButtonLayout = QVBoxLayout()
        dbButtonLayout.addStretch()                     # push the button to the bottom
        dbButtonLayout.addWidget(self.databaseButton)

        formatLayout.addLayout(dbButtonLayout)
        # formatLayout.addWidget(self.databaseButton)
        formatLayout.addStretch()

        selectorLayout.addLayout(formatLayout)
        # selectorLayout.addWidget(QLabel(''))                                    # spacer

        line3 = BlackLine()
        selectorLayout.addWidget(line3)
        selectorLayout.addWidget(QLabel(''))                                    # spacer

        spsFieldLabel = QLabel('Select SPS field to highlight:')
        spsFieldLabel.setStyleSheet(labelStyle)
        selectorLayout.addWidget(spsFieldLabel)
        selectorLayout.addSpacing(6)                                            # small spacer
        # selectorLayout.addWidget(QLabel(''))                                  # spacer

        spsItems = []                                                           # create list of sps items from config.spsPointFormatDict
        for value in config.spsPointFormatDict.values():
            spsItems.append(value)

        xpsItems = []                                                           # create list of xps items from config.spsRelationFormatDict
        for value in config.spsRelationFormatDict.values():
            xpsItems.append(value)

        # SPS highlight fields
        spsLabel2 = QLabel('SPS field')
        spsLabel2.setMaximumWidth(80)  # Fixed width for label

        self.spsCombo = QComboBox()
        self.spsCombo.setSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Fixed)  # Take remaining horizontal space
        self.spsCombo.addItems(spsItems)
        self.spsCombo.highlighted.connect(self.onSpsComboHighlighted)
        self.spsCombo.currentIndexChanged.connect(self.onSpsComboHighlighted)
        self.spsCombo.activated.connect(self.onSpsComboHighlighted)

        spsLabel3 = QLabel('From column:')
        spsLabel3.setMaximumWidth(100)                                          # Fixed width for label

        self.spsFromSpin = QSpinBox()
        self.spsFromSpin.setMinimum(1)                                          # minimum value is 1
        self.spsFromSpin.setMaximumWidth(90)                                    # Fixed width for label
        self.spsFromSpin.valueChanged.connect(self.onSpsSpinboxFromValueChanged)

        spsLabel4 = QLabel('To column:')
        spsLabel4.setMaximumWidth(100)                                          # Fixed width for label

        self.spsToSpin = QSpinBox()
        self.spsToSpin.setMinimum(1)                                            # minimum value is 1
        self.spsToSpin.setMaximumWidth(90)                                      # Fixed width for label
        self.spsToSpin.valueChanged.connect(self.onSpsSpinboxToValueChanged)

        spsLayout2 = QHBoxLayout()
        spsLayout2.addWidget(spsLabel2)
        spsLayout2.addWidget(self.spsCombo)
        spsLayout2.addWidget(spsLabel3)
        spsLayout2.addWidget(self.spsFromSpin)
        spsLayout2.addWidget(spsLabel4)
        spsLayout2.addWidget(self.spsToSpin)
        selectorLayout.addLayout(spsLayout2)

        # XPS highlight fields
        xpsLabel2 = QLabel('XPS field')
        xpsLabel2.setMaximumWidth(80)  # Fixed width for label

        self.xpsCombo = QComboBox()
        self.xpsCombo.setSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Fixed)  # Take remaining horizontal space
        self.xpsCombo.addItems(xpsItems)
        self.xpsCombo.highlighted.connect(self.onXpsComboHighlighted)
        self.xpsCombo.currentIndexChanged.connect(self.onXpsComboHighlighted)
        self.xpsCombo.activated.connect(self.onXpsComboHighlighted)

        xpsLabel3 = QLabel('From column:')
        xpsLabel3.setMaximumWidth(100)  # Fixed width for label

        self.xpsFromSpin = QSpinBox()
        self.xpsFromSpin.setMinimum(1)                                          # minimum value is 1
        self.xpsFromSpin.setMaximumWidth(90)                                    # Fixed width for label
        self.xpsFromSpin.valueChanged.connect(self.onXpsSpinboxFromValueChanged)

        xpsLabel4 = QLabel('To column:')
        xpsLabel4.setMaximumWidth(100)                                          # Fixed width for label

        self.xpsToSpin = QSpinBox()
        self.xpsToSpin.setMinimum(1)                                            # minimum value is 1
        self.xpsToSpin.setMaximumWidth(90)                                      # Fixed width for label
        self.xpsToSpin.valueChanged.connect(self.onXpsSpinboxToValueChanged)

        xpsLayout2 = QHBoxLayout()
        xpsLayout2.addWidget(xpsLabel2)
        xpsLayout2.addWidget(self.xpsCombo)
        xpsLayout2.addWidget(xpsLabel3)
        xpsLayout2.addWidget(self.xpsFromSpin)
        xpsLayout2.addWidget(xpsLabel4)
        xpsLayout2.addWidget(self.xpsToSpin)
        selectorLayout.addLayout(xpsLayout2)

        # RPS highlight fields
        rpsLabel2 = QLabel('RPS field')
        rpsLabel2.setMaximumWidth(80)                                           # Fixed width for label

        self.rpsCombo = QComboBox()
        self.rpsCombo.setSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Fixed)
        self.rpsCombo.addItems(spsItems)
        self.rpsCombo.highlighted.connect(self.onRpsComboHighlighted)
        self.rpsCombo.currentIndexChanged.connect(self.onRpsComboHighlighted)
        self.rpsCombo.activated.connect(self.onRpsComboHighlighted)

        rpsLabel3 = QLabel('From column:')
        rpsLabel3.setMaximumWidth(100)                                          # Fixed width for label

        self.rpsFromSpin = QSpinBox()
        self.rpsFromSpin.setMinimum(1)                                          # minimum value is 1
        self.rpsFromSpin.setMaximumWidth(90)                                    # Fixed width for label
        self.rpsFromSpin.valueChanged.connect(self.onRpsSpinboxFromValueChanged)

        rpsLabel4 = QLabel('To column:')
        rpsLabel4.setMaximumWidth(100)                                          # Fixed width for label

        self.rpsToSpin = QSpinBox()
        self.rpsToSpin.setMinimum(1)                                            # minimum value is 1
        self.rpsToSpin.setMaximumWidth(90)                                      # Fixed width for label
        self.rpsToSpin.valueChanged.connect(self.onRpsSpinboxToValueChanged)

        rpsLayout2 = QHBoxLayout()
        rpsLayout2.addWidget(rpsLabel2)
        rpsLayout2.addWidget(self.rpsCombo)
        rpsLayout2.addWidget(rpsLabel3)
        rpsLayout2.addWidget(self.rpsFromSpin)
        rpsLayout2.addWidget(rpsLabel4)
        rpsLayout2.addWidget(self.rpsToSpin)
        selectorLayout.addLayout(rpsLayout2)

        # Tab widget for SPS, XPS, RPS content display
        self.tabWidget = QTabWidget()
        self.tabWidget.setTabPosition(QTabWidget.TabPosition.South)
        self.tabWidget.setTabShape(QTabWidget.TabShape.Rounded)
        self.tabWidget.setDocumentMode(False)                               # has only effect on OSX ?!
        self.tabWidget.resize(300, 300)

        self.spsTab = CustomPlainTextEdit()
        self.xpsTab = CustomPlainTextEdit()
        self.rpsTab = CustomPlainTextEdit()

        self.spsHighlighter = LineHighlighter(self.spsTab.document())
        self.xpsHighlighter = LineHighlighter(self.xpsTab.document())
        self.rpsHighlighter = LineHighlighter(self.rpsTab.document())

        self.tabWidget.addTab(self.spsTab, 'SPS')
        self.tabWidget.addTab(self.xpsTab, 'XPS')
        self.tabWidget.addTab(self.rpsTab, 'RPS')
        selectorLayout.addWidget(self.tabWidget)

        self.progressLabel = QLabel('Ready')
        self.progressBar = QProgressBar()
        self.progressBar.setRange(0, 100)
        self.progressBar.setValue(0)
        self.progressBar.hide()

        progressLayout = QHBoxLayout()
        progressLayout.addWidget(self.progressLabel)
        progressLayout.addWidget(self.progressBar)
        selectorLayout.addLayout(progressLayout)

        buttons = QDialogButtonBox.StandardButton.Ok | QDialogButtonBox.StandardButton.Cancel
        self.buttonBox = QDialogButtonBox(buttons)
        self.buttonBox.button(QDialogButtonBox.StandardButton.Ok).setText('Import')  # Change "OK" to "Import"
        self.buttonBox.accepted.connect(self.accept)
        self.buttonBox.rejected.connect(self.reject)
        selectorLayout.addWidget(self.buttonBox)

        self.setLayout(selectorLayout)

    def populateSpsFormatList(self):
        self.spsFormatListInitializing = True
        prevBlocked = self.spsFormatList.blockSignals(True)
        self.spsFormatList.clear()
        for fmt in self.appSettings.spsFormatList:
            item = QListWidgetItem(fmt['name'])
            item.setFlags(item.flags() | Qt.ItemFlag.ItemIsEditable)
            self.spsFormatList.addItem(item)
        self.spsFormatList.blockSignals(prevBlocked)

        targetRow = 0
        if self.appSettings.spsDialect:
            matches = self.spsFormatList.findItems(self.appSettings.spsDialect, Qt.MatchFlag.MatchExactly)
            if matches:
                targetRow = self.spsFormatList.row(matches[0])

        if self.spsFormatList.count():
            self.spsFormatList.setCurrentRow(targetRow)

        self.spsFormatListInitializing = False

    def onResetSpsDatabase(self):
        """Reset the SPS implementation database to the built-in defaults."""
        reply = QMessageBox.question(
            self,
            'Reset SPS database',
            'Reset all SPS, XPS and RPS format definitions to the built-in defaults?',
            QMessageBox.StandardButton.Yes | QMessageBox.StandardButton.No,
            QMessageBox.StandardButton.No,
        )
        if reply != QMessageBox.StandardButton.Yes:
            return

        self.appSettings.resetSpsDatabase(preferredDialect=self.appSettings.spsDialect)
        self.appSettings.activate()

        settings = QSettings(config.organization, config.application)
        for group in (
            'settings/sps/spsFormatList',
            'settings/sps/xpsFormatList',
            'settings/sps/rpsFormatList',
        ):
            settings.beginGroup(group)
            settings.remove('')
            settings.endGroup()
        settings.sync()

        self.populateSpsFormatList()
        self.onSpsFormatChanged(self.spsFormatList.currentRow())

    def onSpsComboHighlighted(self, index):
        # print("SPS item highlighted:", index)

        keys = list(config.spsPointFormatDict.keys())
        if 0 <= index < len(keys):
            spsKey = keys[index]
        else:
            raise IndexError(f"SPS index {index} is out of range for spsPointFormatDict ({len(keys)} entries)")

        spsFormatIndex = self.spsFormatList.currentRow()
        # print("SPS format number:", spsFormatIndex)

        spsFormat = self.appSettings.spsFormatList[spsFormatIndex]
        # print("SPS spsFormat:", spsFormat)

        self._setSpinValue(self.spsFromSpin, spsFormat[spsKey][0] + 1)          # +1 to convert from 0-based to 1-based indexing
        self._setSpinValue(self.spsToSpin, spsFormat[spsKey][1])                # this column is exclusive, so no +1 needed
        # print("SPS from/to:", spsFormat[spsKey][0] + 1, spsFormat[spsKey][1])

        self.spsTab.line1 = spsFormat[spsKey][0]
        self.spsTab.line2 = spsFormat[spsKey][1]

        self.tabWidget.setCurrentIndex(0)  # select SPS Tab
        self.spsTab.update()

    def onXpsComboHighlighted(self, index):
        # print("XPS item highlighted:", index)

        keys = list(config.spsRelationFormatDict.keys())
        if 0 <= index < len(keys):
            xpsKey = keys[index]
        else:
            raise IndexError(f"XPS index {index} is out of range for spsRelationFormatDict ({len(keys)} entries)")

        spsFormatIndex = self.spsFormatList.currentRow()
        # print("SPS format number:", spsFormatIndex)

        if not self.appSettings.xpsFormatList:
            QMessageBox.warning(
                self,
                'Missing XPS formats',
                'No XPS format definitions are available. Reset the SPS/XPS settings '
                'to restore the default relation formats.',
            )
            return

        if not 0 <= spsFormatIndex < len(self.appSettings.xpsFormatList):
            QMessageBox.warning(
                self,
                'Incompatible SPS/XPS formats',
                'The selected SPS format does not have a matching XPS entry. '
                'Reset the SPS/XPS settings to realign the format lists.',
            )
            self.spsFormatList.setCurrentRow(0)
            return

        xpsFormat = self.appSettings.xpsFormatList[spsFormatIndex]
        # print("SPS spsFormat:", spsFormat)

        self._setSpinValue(self.xpsFromSpin, xpsFormat[xpsKey][0] + 1)          # +1 to convert from 0-based to 1-based indexing
        self._setSpinValue(self.xpsToSpin, xpsFormat[xpsKey][1])                # this column is exclusive, so no +1 needed

        self.xpsTab.line1 = xpsFormat[xpsKey][0]
        self.xpsTab.line2 = xpsFormat[xpsKey][1]

        self.tabWidget.setCurrentIndex(1)  # select XPS Tab
        self.xpsTab.update()

    def onRpsComboHighlighted(self, index):
        # print("RPS item highlighted:", index)

        keys = list(config.spsPointFormatDict.keys())
        if 0 <= index < len(keys):
            rpsKey = keys[index]
        else:
            raise IndexError(f"SPS index {index} is out of range for spsPointFormatDict ({len(keys)} entries)")

        rpsFormatIndex = self.spsFormatList.currentRow()
        # print("SPS format number:", rpsFormatIndex)

        rpsFormat = self.appSettings.rpsFormatList[rpsFormatIndex]
        # print("RPS rpsFormat:", rpsFormat)

        self._setSpinValue(self.rpsFromSpin, rpsFormat[rpsKey][0] + 1)     # +1 to convert from 0-based to 1-based indexing
        self._setSpinValue(self.rpsToSpin, rpsFormat[rpsKey][1])           # this column is exclusive, so no +1 needed
        # print("RPS from/to:", rpsFormat[rpsKey][0] + 1, rpsFormat[rpsKey][1])

        self.rpsTab.line1 = rpsFormat[rpsKey][0]
        self.rpsTab.line2 = rpsFormat[rpsKey][1]

        self.tabWidget.setCurrentIndex(2)  # select RPS Tab
        self.rpsTab.update()

    def accept(self):
        self.accepted()
        QDialog.accept(self)

    def accepted(self):
        # sps settings
        self.appSettings.spsDialect = self.spsFormatList.currentItem().text()
        self.appSettings.activate()

    def onSpsFormatChanged(self, row: int):
        if self.spsFormatListInitializing or row < 0:
            return

        index = self.tabWidget.currentIndex()                     # get current tab
        if index == 0:
            self.onSpsComboHighlighted(self.spsCombo.currentIndex())
        elif index == 1:
            self.onXpsComboHighlighted(self.xpsCombo.currentIndex())
        elif index == 2:
            self.onRpsComboHighlighted(self.rpsCombo.currentIndex())

    def onCrsChanged(self, crs):
        """Handle changes in the selected CRS."""

        if not crs.isValid():
            QMessageBox.warning(None, 'Invalid CRS', 'An invalid coordinate system has been selected')
            self.crsWidget.setCrs(self.oldCrs)
            return

        if crs.isGeographic():
            QMessageBox.warning(None, 'Invalid CRS', 'An invalid coordinate system has been selected\nGeographic (using lat/lon coordinates)')
            self.crsWidget.setCrs(self.oldCrs)
            return

        self.crs = crs; self.oldCrs = crs  # noqa: E702

    def onSpsFilesChanged(self, fileNames):
        """Handle changes in selected SPS files."""

        self.fileNames = []                                                  # clear previous filenames and other lists
        self.spsFiles = []
        self.rpsFiles = []
        self.xpsFiles = []

        # Parse space-separated quoted filenames into a list. Example input: '"C:/path/file1.sps" "C:/path/file2.rps"'
        # Parse the input based on whether it contains quotes (multiple files) or not (single file)
        if isinstance(fileNames, str):
            if '"' in fileNames:
                # Multiple files: space-separated quoted strings like '"file1.sps" "file2.rps"'
                try:
                    self.fileNames = shlex.split(fileNames)
                except ValueError:
                    # Fallback if shlex fails (malformed quotes)
                    self.fileNames = fileNames.strip().replace('"', '').split()
            else:
                # Single file: plain path without quotes like 'C:/path/file.sps'
                self.fileNames = [fileNames.strip()] if fileNames.strip() else []
        else:
            # Already a list (edge case for some Qt versions)
            self.fileNames = fileNames

        for fileName in self.fileNames:
            suffix = QFileInfo(fileName).suffix().lower()
            if suffix.startswith('s'):
                self.spsFiles.append(fileName)
            elif suffix.startswith('r'):
                self.rpsFiles.append(fileName)
            elif suffix.startswith('x'):
                self.xpsFiles.append(fileName)
            else:
                baseName = QFileInfo(fileName).completeBaseName()
                QMessageBox.information(None, 'Import error', f"Unsupported file extension in selected file(s):\n\n'{baseName}.{suffix}'\n")
                return False

        # Populate the line edits with space-separated filenames (basename + extension only)
        self.spsEdit.setText(' '.join(f'"{QFileInfo(f).fileName()}"' for f in self.spsFiles))
        self.rpsEdit.setText(' '.join(f'"{QFileInfo(f).fileName()}"' for f in self.rpsFiles))
        self.xpsEdit.setText(' '.join(f'"{QFileInfo(f).fileName()}"' for f in self.xpsFiles))

        spsText = ''
        xpsText = ''
        rpsText = ''

        # local function to safely read sps files with fallback encodings and error handling
        def readTextFileSafe(filePath: str) -> str:
            try:
                with open(filePath, 'rb') as file:
                    totalBytes = max(os.fstat(file.fileno()).st_size, 1)
                    chunks = []
                    bytesRead = 0

                    self._updateFileLoadProgress(filePath, 0)

                    while True:
                        chunk = file.read(64 * 1024)
                        if not chunk:
                            break

                        chunks.append(chunk)
                        bytesRead += len(chunk)
                        progress = min((100 * bytesRead) // totalBytes, 100)
                        self._updateFileLoadProgress(filePath, progress)

                    fileBytes = b''.join(chunks)
                    self._updateFileLoadProgress(filePath, 100)

                try:
                    return fileBytes.decode('utf-8')
                except UnicodeDecodeError:
                    return fileBytes.decode('latin-1', errors='replace')
            except OSError as ex:
                QMessageBox.warning(self, 'File read error', f'Could not read:\n{filePath}\n\n{ex}')
                return ''

        with pg.BusyCursor():                                               # this may take a while; start wait cursor
            for spsFile in self.spsFiles:
                spsText += readTextFileSafe(spsFile)

            for xpsFile in self.xpsFiles:
                xpsText += readTextFileSafe(xpsFile)

            for rpsFile in self.rpsFiles:
                rpsText += readTextFileSafe(rpsFile)

            self._showPreviewPopulateProgress()
            self.spsTab.setPlainText(spsText)  # for some reason unknown, the text is not colored properly, when setPlainText is used
            self.xpsTab.setPlainText(xpsText)  # see: https://doc.qt.io/qtforpython-6.5/examples/example_widgets_richtext_syntaxhighlighter.html
            self.rpsTab.setPlainText(rpsText)

        self._setReadyProgress()

    def _updateFileLoadProgress(self, filePath: str, progress: int):
        self.progressBar.setRange(0, 100)
        self.progressBar.show()
        self.progressLabel.setText(f'Reading: {QFileInfo(filePath).fileName()}')
        self.progressBar.setValue(progress)
        self.progressLabel.repaint()
        self.progressBar.repaint()
        self.repaint()
        QApplication.processEvents()

    def _showPreviewPopulateProgress(self):
        self.progressBar.show()
        self.progressBar.setRange(0, 0)
        self.progressLabel.setText('Preparing preview tabs')
        self.progressLabel.repaint()
        self.progressBar.repaint()
        self.repaint()
        QApplication.processEvents()

    def _setReadyProgress(self):
        self.progressBar.setRange(0, 100)
        self.progressLabel.setText('Ready reading input data')
        self.progressBar.setValue(0)
        self.progressBar.hide()

    def _setSpinValue(self, spinBox: QSpinBox, value: int):
        prev = spinBox.blockSignals(True)
        try:
            spinBox.setValue(value)
        finally:
            spinBox.blockSignals(prev)

    def onSpsSpinboxFromValueChanged(self, _):
        self.onSpsSpinboxValueChanged(ColumnBound.FROM)

    def onSpsSpinboxToValueChanged(self, _):
        self.onSpsSpinboxValueChanged(ColumnBound.TO)

    def onXpsSpinboxFromValueChanged(self, _):
        self.onXpsSpinboxValueChanged(ColumnBound.FROM)

    def onXpsSpinboxToValueChanged(self, _):
        self.onXpsSpinboxValueChanged(ColumnBound.TO)

    def onRpsSpinboxFromValueChanged(self, _):
        self.onRpsSpinboxValueChanged(ColumnBound.FROM)

    def onRpsSpinboxToValueChanged(self, _):
        self.onRpsSpinboxValueChanged(ColumnBound.TO)

    def onSpsSpinboxValueChanged(self, bound: ColumnBound):
        bound = ColumnBound(bound)

        minCol = self.spsFromSpin.value() - 1                                   # -1 to convert from 1-based to 0-based indexing
        maxCol = self.spsToSpin.value()                                         # this column is exclusive, so no -1 needed

        # make sure from is always less than to
        minCol2 = min(minCol, maxCol)
        maxCol2 = max(maxCol, minCol)

        if minCol2 == maxCol2:                                                  # prevent equal values
            if bound is ColumnBound.FROM:
                maxCol2 = minCol2 + 1
            else:
                minCol2 = maxCol2 - 1

        self._setSpinValue(self.spsFromSpin, minCol2 + 1)
        self._setSpinValue(self.spsToSpin, maxCol2)

        spsFormatIndex = self.spsFormatList.currentRow()
        spsKey = list(config.spsPointFormatDict.keys())[self.spsCombo.currentIndex()]

        self.appSettings.spsFormatList[spsFormatIndex][spsKey][0] = minCol2
        self.appSettings.spsFormatList[spsFormatIndex][spsKey][1] = maxCol2

        self.spsTab.line1 = self.appSettings.spsFormatList[spsFormatIndex][spsKey][0]
        self.spsTab.line2 = self.appSettings.spsFormatList[spsFormatIndex][spsKey][1]

        self.tabWidget.setCurrentIndex(0)                                       # select SPS Tab
        self.spsTab.update()

    def onXpsSpinboxValueChanged(self, bound: ColumnBound):
        bound = ColumnBound(bound)

        minCol = self.xpsFromSpin.value() - 1                                   # -1 to convert from 1-based to 0-based indexing
        maxCol = self.xpsToSpin.value()                                         # this column is exclusive, so no -1 needed

        # make sure from is always less than to
        minCol2 = min(minCol, maxCol)
        maxCol2 = max(maxCol, minCol)

        if minCol2 == maxCol2:                                                  # prevent equal values
            if bound is ColumnBound.FROM:
                maxCol2 = minCol2 + 1
            else:
                minCol2 = maxCol2 - 1

        self._setSpinValue(self.xpsFromSpin, minCol2 + 1)
        self._setSpinValue(self.xpsToSpin, maxCol2)

        spsFormatIndex = self.spsFormatList.currentRow()
        spsKey = list(config.spsRelationFormatDict.keys())[self.xpsCombo.currentIndex()]

        self.appSettings.xpsFormatList[spsFormatIndex][spsKey][0] = minCol2
        self.appSettings.xpsFormatList[spsFormatIndex][spsKey][1] = maxCol2

        self.spsTab.line1 = self.appSettings.xpsFormatList[spsFormatIndex][spsKey][0]
        self.spsTab.line2 = self.appSettings.xpsFormatList[spsFormatIndex][spsKey][1]

        self.tabWidget.setCurrentIndex(1)                                       # select XPS Tab
        self.xpsTab.update()

    def onRpsSpinboxValueChanged(self, bound: ColumnBound):
        bound = ColumnBound(bound)

        minCol = self.rpsFromSpin.value() - 1                                   # -1 to convert from 1-based to 0-based indexing
        maxCol = self.rpsToSpin.value()                                         # this column is exclusive, so no -1 needed

        # make sure from is always less than to
        minCol2 = min(minCol, maxCol)
        maxCol2 = max(maxCol, minCol)

        if minCol2 == maxCol2:                                                  # prevent equal values
            if bound is ColumnBound.FROM:
                maxCol2 = minCol2 + 1
            else:
                minCol2 = maxCol2 - 1

        self._setSpinValue(self.rpsFromSpin, minCol2 + 1)
        self._setSpinValue(self.rpsToSpin, maxCol2)

        spsFormatIndex = self.spsFormatList.currentRow()
        rpsKey = list(config.spsPointFormatDict.keys())[self.rpsCombo.currentIndex()]

        self.appSettings.rpsFormatList[spsFormatIndex][rpsKey][0] = minCol2
        self.appSettings.rpsFormatList[spsFormatIndex][rpsKey][1] = maxCol2

        self.rpsTab.line1 = self.appSettings.rpsFormatList[spsFormatIndex][rpsKey][0]
        self.rpsTab.line2 = self.appSettings.rpsFormatList[spsFormatIndex][rpsKey][1]

        self.tabWidget.setCurrentIndex(2)                                       # select RPS Tab
        self.rpsTab.update()

    def onAddSpsName(self):
        """Add a new editable entry to the SPS implementations list."""
        newName = 'New Implementation'
        currentItem = self.spsFormatList.currentItem()
        if currentItem is not None:
            # newName = f'{currentItem.text()} copy'
            newName = currentItem.text()

        currentRow = self.spsFormatList.currentRow()
        insertRow = currentRow + 1 if currentRow >= 0 else self.spsFormatList.count()

        newItem = QListWidgetItem(newName)
        newItem.setFlags(newItem.flags() | Qt.ItemFlag.ItemIsEditable)

        existingNames = [self.spsFormatList.item(i).text() for i in range(self.spsFormatList.count())]
        if newName in existingNames:
            match = re.match(r'^(.*?)(?:\s*\((\d+)\))?$', newName)
            base = match.group(1).strip()
            counter = int(match.group(2)) + 1 if match.group(2) else 2
            uniqueName = f'{base} ({counter})'
            while uniqueName in existingNames:
                counter += 1
                uniqueName = f'{base} ({counter})'
            newName = uniqueName

        newItem.setText(newName)

        if not self.appSettings.spsFormatList or not self.appSettings.xpsFormatList:
            QMessageBox.warning(self, 'Add SPS format', 'No reference SPS/XPS format is available to duplicate.')
            return

        referenceRow = currentRow if currentRow >= 0 else 0
        referenceRow = min(referenceRow, len(self.appSettings.spsFormatList) - 1)

        newSpsFormat = copy.deepcopy(self.appSettings.spsFormatList[referenceRow])
        newXpsFormat = copy.deepcopy(self.appSettings.xpsFormatList[referenceRow])
        newRpsFormat = copy.deepcopy(self.appSettings.rpsFormatList[referenceRow])
        newSpsFormat['name'] = newName
        newXpsFormat['name'] = newName
        newRpsFormat['name'] = newName

        self.spsFormatList.insertItem(insertRow, newItem)

        self.appSettings.spsFormatList.insert(insertRow, newSpsFormat)
        self.appSettings.xpsFormatList.insert(insertRow, newXpsFormat)
        self.appSettings.rpsFormatList.insert(insertRow, newRpsFormat)

        prevBlocked = self.spsFormatList.blockSignals(True)
        self.spsFormatList.setCurrentRow(insertRow)
        self.spsFormatList.blockSignals(prevBlocked)

        self.onSpsFormatChanged(insertRow)

    def onRemoveSpsName(self):
        """Remove the currently selected entry from the list."""
        currentRow = self.spsFormatList.currentRow()
        if currentRow < 0:
            QMessageBox.information(self, 'Remove SPS format', 'Please select an item to remove.')
            return

        self.spsFormatList.takeItem(currentRow)

        if 0 <= currentRow < len(self.appSettings.spsFormatList):
            del self.appSettings.spsFormatList[currentRow]
        if 0 <= currentRow < len(self.appSettings.xpsFormatList):
            del self.appSettings.xpsFormatList[currentRow]
        if 0 <= currentRow < len(self.appSettings.rpsFormatList):
            del self.appSettings.rpsFormatList[currentRow]

        nextRow = min(currentRow, self.spsFormatList.count() - 1)
        if nextRow >= 0:
            prevBlocked = self.spsFormatList.blockSignals(True)
            self.spsFormatList.setCurrentRow(nextRow)
            self.spsFormatList.blockSignals(prevBlocked)
            self.onSpsFormatChanged(nextRow)

    def ensureUniqueSpsName(self, item: QListWidgetItem):
        if not self.enforceUniqueName or item is None:
            return

        name = item.text().strip()
        if not name:
            name = 'Unnamed'

        names = []
        for i in range(self.spsFormatList.count()):
            other = self.spsFormatList.item(i)
            if other is item:
                continue
            names.append(other.text())

        if name not in names:                           # name is unique; done
            item.setText(name)

            index = self.spsFormatList.row(item)                                # make sure the config entries are also updated
            if 0 <= index < len(self.appSettings.spsFormatList):
                self.appSettings.spsFormatList[index]['name'] = name
                self.appSettings.xpsFormatList[index]['name'] = name
                self.appSettings.rpsFormatList[index]['name'] = name
            return

        match = re.match(r'^(.*?)(?:\s*\((\d+)\))?$', name)
        base = match.group(1).strip()
        counter = int(match.group(2)) + 1 if match.group(2) else 2

        unique = f'{base} ({counter})'
        while unique in names:
            counter += 1
            unique = f'{base} ({counter})'

        self.enforceUniqueName = False
        try:
            item.setText(unique)
        finally:
            self.enforceUniqueName = True

        index = self.spsFormatList.row(item)
        if 0 <= index < len(self.appSettings.spsFormatList):
            self.appSettings.spsFormatList[index]['name'] = unique
            self.appSettings.xpsFormatList[index]['name'] = unique
            self.appSettings.rpsFormatList[index]['name'] = unique
