Display changelog in about dialog

sohstationviewer/view/about_dialog.py

 import sys
-from typing import Union
+from typing import Union, Dict
+import os
+from pathlib import Path
+import re
 
 from PySide6 import QtWidgets, QtCore
-from PySide6.QtWidgets import QApplication, QWidget, QDialog, QLabel, QFrame
+from PySide6.QtWidgets import QApplication, QWidget, QDialog, QLabel, QFrame, \
+    QListWidget, QPlainTextEdit
 
 from sohstationviewer.conf import constants
 
@@ -18,6 +22,17 @@ def add_separation_line(layout):
     layout.addWidget(label)
 
 
+def remove_empty_lines(text: str) -> str:
+    """
+    Remove lines with no text from text
+    :param text: the text with empty lines that need to be removed
+    :return: text with no empty lines
+    """
+    lines = text.split('\n')
+    no_empty_lines = [line for line in lines if line.strip()]
+    return '\n'.join(no_empty_lines)
+
+
 class AboutDialog(QDialog):
     """
      Dialog to show information of the software.
@@ -25,7 +40,7 @@ class AboutDialog(QDialog):
      About Dialog is always opened and will be raised up when the about menu
      action is triggered.
     """
-    def __init__(self, parent: Union[QWidget, QApplication]):
+    def __init__(self, parent: Union[QWidget, QApplication, None]):
         """
         :param parent: the parent widget
         """
@@ -41,18 +56,31 @@ class AboutDialog(QDialog):
                        "by different types of data loggers.")
         self.description_label = QLabel(description)
 
+        self.history_label = QLabel('History')
+        # Dictionary of history by version
+        self.history_dict: Dict[str, str] = self.get_history_dict()
+
+        self.version_list_widget = QListWidget(self)
+        self.version_list_widget.addItems(reversed(self.history_dict.keys()))
+
+        self.changelog_edit = QPlainTextEdit()
+        self.changelog_edit.setReadOnly(True)
+
         version = f"Version {constants.SOFTWARE_VERSION}"
         self.version_label = QLabel(version)
 
         built_time = f"Built on {constants.BUILD_TIME}"
         self.built_time_label = QLabel(built_time)
 
-        copyright = u"Copyright \u00A9 2024 EarthScope Consortium"
-        self.copyright_label = QLabel(copyright)
+        version_year = constants.SOFTWARE_VERSION.split('.')[0]
+        copy_right = (u"Copyright \u00A9 "
+                      f"{version_year} EarthScope Consortium")
+        self.copyright_label = QLabel(copy_right)
 
         self.ok_button = QtWidgets.QPushButton('OK', self)
         self.setup_ui()
         self.connect_signals()
+        self.version_list_widget.setCurrentRow(0)
 
     def setup_ui(self):
         self.setWindowTitle("About SOHViewer")
@@ -63,6 +91,13 @@ class AboutDialog(QDialog):
         main_layout.addWidget(self.description_label)
         add_separation_line(main_layout)
 
+        main_layout.addWidget(self.history_label)
+        history_layout = QtWidgets.QHBoxLayout()
+        main_layout.addLayout(history_layout)
+        self.version_list_widget.setFixedWidth(100)
+        history_layout.addWidget(self.version_list_widget)
+        history_layout.addWidget(self.changelog_edit)
+
         main_layout.addWidget(self.version_label)
         main_layout.addWidget(self.built_time_label)
         main_layout.addWidget(self.copyright_label)
@@ -73,8 +108,45 @@ class AboutDialog(QDialog):
         button_layout.addWidget(self.ok_button)
 
     def connect_signals(self) -> None:
+        self.version_list_widget.currentTextChanged.connect(
+            self.on_version_changed)
         self.ok_button.clicked.connect(self.close)
 
+    @staticmethod
+    def get_history_dict():
+        """
+        Get dictionary of history by version from file HISTORY.rst
+        :return: dictionary of history by version
+        """
+        current_file_path = os.path.abspath(__file__)
+        root = Path(current_file_path).parent.parent.parent
+        history_path = root.joinpath('HISTORY.rst')
+        version_re = re.compile('^[1-3][0-9]{3}.[1-9].[0-9].[0-9]$')
+        history_dict = {}
+        lines = []
+        version = None
+        with open(history_path) as file:
+            lines = file.readlines()
+        for line in lines:
+            line = line.strip()
+            if version_re.match(line):
+                version = line
+                history_dict[version] = ""
+            elif version is not None and '------' not in line:
+                history_dict[version] += line + '\n'
+        return history_dict
+
+    @QtCore.Slot()
+    def on_version_changed(self, version):
+        """
+        When version is changed, place the corresponded changelog in changelog
+        edit.
+        :param version: the selected version
+        """
+        changelog = remove_empty_lines(self.history_dict[version])
+
+        self.changelog_edit.setPlainText(changelog)
+
 
 if __name__ == '__main__':
     app = QtWidgets.QApplication(sys.argv)