Move page index logic into WelcomePagesModel

cura/UI/WelcomePagesModel.py

@@ -1,10 +1,12 @@
 # Copyright (c) 2019 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
+from collections import deque
 import os
-from typing import TYPE_CHECKING, Optional, List, Dict, Any
+from typing import TYPE_CHECKING, Optional, List, Dict, Any, Deque
 
-from PyQt5.QtCore import QUrl, Qt
+from PyQt5.QtCore import QUrl, Qt, pyqtSlot, pyqtProperty, pyqtSignal
 
+from UM.Logger import Logger
 from UM.Qt.ListModel import ListModel
 from UM.Resources import Resources
 
@@ -27,6 +29,99 @@ class WelcomePagesModel(ListModel):
 
         self._pages = []  # type: List[Dict[str, Any]]
 
+        self._current_page_index = 0
+        # Store all the previous page indices so it can go back.
+        self._previous_page_indices_stack = deque()  # type: Deque[int]
+
+    allFinished = pyqtSignal()  # emitted when all steps have been finished
+    currentPageIndexChanged = pyqtSignal()
+
+    @pyqtProperty(int, notify = currentPageIndexChanged)
+    def currentPageIndex(self) -> int:
+        return self._current_page_index
+
+    # Returns a float number in [0, 1] which indicates the current progress.
+    @pyqtProperty(float, notify = currentPageIndexChanged)
+    def currentProgress(self) -> float:
+        return self._current_page_index / len(self._items)
+
+    # Indicates if the current page is the last page.
+    @pyqtProperty(bool, notify = currentPageIndexChanged)
+    def isCurrentPageLast(self) -> bool:
+        return self._current_page_index == len(self._items) - 1
+
+    def _setCurrentPageIndex(self, page_index: int) -> None:
+        if page_index != self._current_page_index:
+            self._previous_page_indices_stack.append(self._current_page_index)
+            self._current_page_index = page_index
+            self.currentPageIndexChanged.emit()
+
+    # Goes to the next page.
+    @pyqtSlot()
+    def goToNextPage(self) -> None:
+        page_item = self._items[self._current_page_index]
+        # Check if there's a "next_page_id" assigned. If so, go to that page. Otherwise, go to the page with the
+        # current index + 1.
+        next_page_id = page_item.get("next_page_id")
+        next_page_index = self._current_page_index + 1
+        if next_page_id:
+            idx = self.getPageIndexById(next_page_id)
+            if idx is None:
+                # FIXME: If we cannot find the next page, we cannot do anything here.
+                Logger.log("e", "Cannot find page with ID [%s]", next_page_id)
+                return
+            next_page_index = idx
+
+        # If we have reached the last page, emit allFinished signal and reset.
+        if next_page_index == len(self._items):
+            self.allFinished.emit()
+            self.resetState()
+
+        # Move to the next page
+        self._setCurrentPageIndex(next_page_index)
+
+    # Goes to the previous page. If there's no previous page, do nothing.
+    @pyqtSlot()
+    def goToPreviousPage(self) -> None:
+        if len(self._previous_page_indices_stack) == 0:
+            Logger.log("i", "No previous page, do nothing")
+            return
+
+        previous_page_index = self._previous_page_indices_stack.pop()
+        self._current_page_index = previous_page_index
+        self.currentPageIndexChanged.emit()
+
+    # Sets the current page to the given page ID. If the page ID is not found, do nothing.
+    @pyqtSlot(str)
+    def goToPage(self, page_id: str) -> None:
+        page_index = self.getPageIndexById(page_id)
+        if page_index is None:
+            # FIXME: If we cannot find the next page, we cannot do anything here.
+            Logger.log("e", "Cannot find page with ID [%s]", page_index)
+            return
+
+        # Move to that page
+        self._setCurrentPageIndex(page_index)
+
+    # Resets the state of the WelcomePagesModel. This functions does the following:
+    #  - Resets current_page_index to 0
+    #  - Clears the previous page indices stack
+    @pyqtSlot()
+    def resetState(self) -> None:
+        self._current_page_index = 0
+        self._previous_page_indices_stack.clear()
+
+        self.currentPageIndexChanged.emit()
+
+    # Gets the page index with the given page ID. If the page ID doesn't exist, returns None.
+    def getPageIndexById(self, page_id: str) -> Optional[int]:
+        page_idx = None
+        for idx, page_item in enumerate(self._items):
+            if page_item["id"] == page_id:
+                page_idx = idx
+                break
+        return page_idx
+
     # Convenience function to get QUrl path to pages that's located in "resources/qml/WelcomePages".
     def _getBuiltinWelcomePagePath(self, page_filename: str) -> "QUrl":
         from cura.CuraApplication import CuraApplication
@@ -49,9 +144,11 @@ class WelcomePagesModel(ListModel):
                             })
         self._pages.append({"id": "add_network_or_local_printer",
                             "page_url": self._getBuiltinWelcomePagePath("AddNetworkOrLocalPrinterContent.qml"),
+                            "next_page_id": "machine_actions",
                             })
         self._pages.append({"id": "add_printer_by_ip",
                             "page_url": self._getBuiltinWelcomePagePath("AddPrinterByIpContent.qml"),
+                            "next_page_id": "machine_actions",
                             })
         self._pages.append({"id": "machine_actions",
                             "page_url": self._getBuiltinWelcomePagePath("FirstStartMachineActionsContent.qml"),