"""
novelWriter – GUI Document Viewer Panel
=======================================

This file is a part of novelWriter
Copyright (C) 2023 Veronica Berglyd Olsen and novelWriter contributors

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
"""  # noqa

from __future__ import annotations

import logging

from enum import Enum
from typing import TYPE_CHECKING

from PyQt6.QtCore import QModelIndex, Qt, pyqtSignal, pyqtSlot
from PyQt6.QtWidgets import (
    QAbstractItemView,
    QFrame,
    QMenu,
    QTabWidget,
    QToolButton,
    QTreeWidget,
    QTreeWidgetItem,
    QVBoxLayout,
    QWidget,
)

from novelwriter import SHARED
from novelwriter.common import checkInt, qtAddAction
from novelwriter.constants import nwLabels, nwLists, nwStyles, trConst
from novelwriter.enum import nwChange, nwDocMode, nwItemClass
from novelwriter.extensions.modified import NIconToolButton
from novelwriter.gui.theme import STYLES_FLAT_TABS, STYLES_MIN_TOOLBUTTON
from novelwriter.types import QtDecorationRole, QtHeaderFixed, QtHeaderToContents, QtUserRole

if TYPE_CHECKING:
    from novelwriter.core.indexdata import IndexHeading, IndexNode

logger = logging.getLogger(__name__)


class GuiDocViewerPanel(QWidget):
    """GUI: Document Viewer Panel.

    The panel of project meta data below the viewer.
    """

    openDocumentRequest = pyqtSignal(str, Enum, str, bool)
    loadDocumentTagRequest = pyqtSignal(str, Enum)

    def __init__(self, parent: QWidget) -> None:
        super().__init__(parent=parent)

        logger.debug("Create: GuiDocViewerPanel")

        self._lastHandle = None

        iSz = SHARED.theme.baseIconSize

        self.tabBackRefs = _ViewPanelBackRefs(self)

        self.optsMenu = QMenu(self)

        self.aInactive = qtAddAction(self.optsMenu, self.tr("Hide Inactive Tags"))
        self.aInactive.setCheckable(True)
        self.aInactive.toggled.connect(self._toggleHideInactive)

        self.optsButton = NIconToolButton(self, iSz)
        self.optsButton.setToolTip(self.tr("Options"))
        self.optsButton.setMenu(self.optsMenu)
        self.optsButton.setPopupMode(QToolButton.ToolButtonPopupMode.InstantPopup)

        self.mainTabs = QTabWidget(self)
        self.mainTabs.addTab(self.tabBackRefs, self.tr("References"))
        self.mainTabs.setCornerWidget(self.optsButton, Qt.Corner.TopLeftCorner)

        self.kwTabs: dict[str, _ViewPanelKeyWords] = {}
        self.idTabs: dict[str, int] = {}
        for itemClass in nwLists.USER_CLASSES:
            cTab = _ViewPanelKeyWords(self, itemClass)
            tabId = self.mainTabs.addTab(cTab, trConst(nwLabels.CLASS_NAME[itemClass]))
            self.kwTabs[itemClass.name] = cTab
            self.idTabs[itemClass.name] = tabId

        # Assemble
        self.outerBox = QVBoxLayout()
        self.outerBox.addWidget(self.mainTabs)
        self.outerBox.setContentsMargins(0, 0, 0, 0)

        self.setLayout(self.outerBox)
        self.updateTheme(updateTabs=False)

        logger.debug("Ready: GuiDocViewerPanel")

    ##
    #  Methods
    ##

    def updateTheme(self, updateTabs: bool = True) -> None:
        """Update theme elements."""
        logger.debug("Theme Update: GuiDocViewerPanel")

        self.optsButton.setThemeIcon("more_vertical", "default")
        self.optsButton.setStyleSheet(SHARED.theme.getStyleSheet(STYLES_MIN_TOOLBUTTON))
        self.mainTabs.setStyleSheet(SHARED.theme.getStyleSheet(STYLES_FLAT_TABS))
        if updateTabs:
            self.tabBackRefs.updateTheme()
            self.tabBackRefs.refreshContent(self._lastHandle)
            for tab in self.kwTabs.values():
                tab.updateTheme()
            self._loadAllTags()

    def openProjectTasks(self) -> None:
        """Run open project tasks."""
        colWidths = SHARED.project.options.getValue("GuiDocViewerPanel", "colWidths", {})
        hideInactive = SHARED.project.options.getBool("GuiDocViewerPanel", "hideInactive", False)
        self.aInactive.setChecked(hideInactive)
        if isinstance(colWidths, dict):
            for key, value in colWidths.items():
                if key in self.kwTabs and isinstance(value, list):
                    self.kwTabs[key].setColumnWidths(value)

    def closeProjectTasks(self) -> None:
        """Run close project tasks."""
        logger.debug("Saving State: GuiDocViewerPanel")
        colWidths = {k: t.getColumnWidths() for k, t in self.kwTabs.items()}
        hideInactive = self.aInactive.isChecked()
        SHARED.project.options.setValue("GuiDocViewerPanel", "colWidths", colWidths)
        SHARED.project.options.setValue("GuiDocViewerPanel", "hideInactive", hideInactive)

    ##
    #  Public Slots
    ##

    @pyqtSlot()
    def indexWasCleared(self) -> None:
        """Handle event when the index has been cleared of content."""
        self.tabBackRefs.clearContent()
        for cTab in self.kwTabs.values():
            cTab.clearContent()

    @pyqtSlot()
    def indexHasAppeared(self) -> None:
        """Handle event when the index has appeared."""
        self._loadAllTags()
        self._updateTabVisibility()
        self.updateHandle(self._lastHandle)

    @pyqtSlot(str, Enum)
    def onProjectItemChanged(self, tHandle: str, change: nwChange) -> None:
        """Update meta data for project item."""
        self.tabBackRefs.refreshDocument(tHandle)
        activeOnly = self.aInactive.isChecked()
        for key in SHARED.project.index.getDocumentTags(tHandle):
            name, tClass, iItem, hItem = SHARED.project.index.getSingleTag(key)
            if tClass in self.kwTabs and iItem and hItem:
                if not activeOnly or (iItem and iItem.item.isActive):
                    self.kwTabs[tClass].addUpdateEntry(key, name, iItem, hItem)
                else:
                    self.kwTabs[tClass].removeEntry(key)
        self._updateTabVisibility()

    @pyqtSlot(str)
    def updateHandle(self, tHandle: str | None) -> None:
        """Update the document handle."""
        self._lastHandle = tHandle
        self.tabBackRefs.refreshContent(tHandle or None)

    @pyqtSlot(list, list)
    def updateChangedTags(self, updated: list[str], deleted: list[str]) -> None:
        """Forward tags changes to the lists."""
        for key in updated:
            name, tClass, iItem, hItem = SHARED.project.index.getSingleTag(key)
            if tClass in self.kwTabs and iItem and hItem:
                self.kwTabs[tClass].addUpdateEntry(key, name, iItem, hItem)
        for key in deleted:
            for cTab in self.kwTabs.values():
                if cTab.removeEntry(key):
                    break
            else:
                logger.warning("Could not remove tag '%s' from view panel", key)
        self._updateTabVisibility()

    @pyqtSlot(str)
    def updateStatusLabels(self, kind: str) -> None:
        """Update the importance labels."""
        if kind == "i":
            self._loadAllTags()

    ##
    #  Private Slots
    ##

    @pyqtSlot(bool)
    def _toggleHideInactive(self, state: bool) -> None:
        """Process toggling of active/inactive visibility."""
        logger.debug("Setting inactive items to %s", "hidden" if state else "visible")
        for cTab in self.kwTabs.values():
            cTab.clearContent()
        self._loadAllTags()
        self._updateTabVisibility()

    ##
    #  Internal Functions
    ##

    def _updateTabVisibility(self) -> None:
        """Hide class tabs with no content."""
        for tClass, cTab in self.kwTabs.items():
            self.mainTabs.setTabVisible(self.idTabs[tClass], cTab.countEntries() > 0)

    def _loadAllTags(self) -> None:
        """Load all tags into the tabs."""
        data = SHARED.project.index.getTagsData(activeOnly=self.aInactive.isChecked())
        for key, name, tClass, iItem, hItem in data:
            if tClass in self.kwTabs and iItem and hItem:
                self.kwTabs[tClass].addUpdateEntry(key, name, iItem, hItem)


class _ViewPanelBackRefs(QTreeWidget):
    C_DATA = 0
    C_DOC = 0
    C_EDIT = 1
    C_VIEW = 2
    C_TITLE = 3

    D_HANDLE = QtUserRole

    def __init__(self, parent: GuiDocViewerPanel) -> None:
        super().__init__(parent=parent)

        self._parent = parent
        self._treeMap: dict[str, QTreeWidgetItem] = {}

        iPx = SHARED.theme.baseIconHeight
        iSz = SHARED.theme.baseIconSize

        self.setHeaderLabels([self.tr("Document"), "", "", self.tr("First Heading")])
        self.setIndentation(0)
        self.setSelectionMode(QAbstractItemView.SelectionMode.NoSelection)
        self.setIconSize(iSz)
        self.setFrameStyle(QFrame.Shape.NoFrame)

        # Set Header Sizes
        if header := self.header():
            header.setStretchLastSection(True)
            header.setMinimumSectionSize(iPx + 6)  # See Issue #1627
            header.setSectionResizeMode(self.C_DOC, QtHeaderToContents)
            header.setSectionResizeMode(self.C_EDIT, QtHeaderFixed)
            header.setSectionResizeMode(self.C_VIEW, QtHeaderFixed)
            header.setSectionResizeMode(self.C_TITLE, QtHeaderToContents)
            header.resizeSection(self.C_EDIT, iPx + 6)
            header.resizeSection(self.C_VIEW, iPx + 6)
            header.setSectionsMovable(False)

        # Cache Icons Locally
        self._editIcon = SHARED.theme.getIcon("edit", "change")
        self._viewIcon = SHARED.theme.getIcon("view", "action")

        # Signals
        self.clicked.connect(self._treeItemClicked)
        self.doubleClicked.connect(self._treeItemDoubleClicked)

    def updateTheme(self) -> None:
        """Update theme elements."""
        logger.debug("Theme Update: _ViewPanelBackRefs")

        self._editIcon = SHARED.theme.getIcon("edit", "change")
        self._viewIcon = SHARED.theme.getIcon("view", "action")
        for i in range(self.topLevelItemCount()):
            if item := self.topLevelItem(i):
                item.setIcon(self.C_EDIT, self._editIcon)
                item.setIcon(self.C_VIEW, self._viewIcon)

    def clearContent(self) -> None:
        """Clear the widget."""
        self.clear()
        self._treeMap = {}

    def refreshContent(self, dHandle: str | None) -> None:
        """Update the content."""
        self.clearContent()
        if dHandle:
            refs = SHARED.project.index.getBackReferenceList(dHandle)
            for tHandle, (sTitle, hItem) in refs.items():
                self._setTreeItemValues(tHandle, sTitle, hItem)

    def refreshDocument(self, tHandle: str) -> None:
        """Refresh document meta data."""
        if iItem := SHARED.project.index.getItemData(tHandle):
            for sTitle, hItem in iItem.items():
                if f"{tHandle}:{sTitle}" in self._treeMap:
                    self._setTreeItemValues(tHandle, sTitle, hItem)

    ##
    #  Private Slots
    ##

    @pyqtSlot("QModelIndex")
    def _treeItemClicked(self, index: QModelIndex) -> None:
        """Emit document open signal on user click."""
        tHandle = index.siblingAtColumn(self.C_DATA).data(self.D_HANDLE)
        if index.column() == self.C_EDIT:
            self._parent.openDocumentRequest.emit(tHandle, nwDocMode.EDIT, "", True)
        elif index.column() == self.C_VIEW:
            self._parent.openDocumentRequest.emit(tHandle, nwDocMode.VIEW, "", True)

    @pyqtSlot("QModelIndex")
    def _treeItemDoubleClicked(self, index: QModelIndex) -> None:
        """Emit follow tag signal on user double click."""
        tHandle = index.siblingAtColumn(self.C_DATA).data(self.D_HANDLE)
        if index.column() not in (self.C_EDIT, self.C_VIEW):
            self._parent.openDocumentRequest.emit(tHandle, nwDocMode.VIEW, "", True)

    ##
    #  Internal Functions
    ##

    def _setTreeItemValues(self, tHandle: str, sTitle: str, hItem: IndexHeading) -> None:
        """Add or update a tree item."""
        if nwItem := SHARED.project.tree[tHandle]:
            iLevel = nwStyles.H_LEVEL.get(hItem.level, 0) if nwItem.isDocumentLayout() else 5
            hDec = SHARED.theme.getHeaderDecorationNarrow(iLevel)

            tKey = f"{tHandle}:{sTitle}"
            trItem = self._treeMap[tKey] if tKey in self._treeMap else QTreeWidgetItem()

            trItem.setIcon(self.C_DOC, nwItem.getMainIcon())
            trItem.setText(self.C_DOC, nwItem.itemName)
            trItem.setToolTip(self.C_DOC, nwItem.itemName)
            trItem.setIcon(self.C_EDIT, self._editIcon)
            trItem.setIcon(self.C_VIEW, self._viewIcon)
            trItem.setData(self.C_TITLE, QtDecorationRole, hDec)
            trItem.setText(self.C_TITLE, hItem.title)
            trItem.setToolTip(self.C_TITLE, hItem.title)
            trItem.setData(self.C_DATA, self.D_HANDLE, tHandle)

            if tKey not in self._treeMap:
                self.addTopLevelItem(trItem)
                self._treeMap[tKey] = trItem


class _ViewPanelKeyWords(QTreeWidget):
    C_DATA = 0
    C_NAME = 0
    C_EDIT = 1
    C_VIEW = 2
    C_IMPORT = 3
    C_DOC = 4
    C_TITLE = 5
    C_SHORT = 6

    D_TAG = QtUserRole

    def __init__(self, parent: GuiDocViewerPanel, itemClass: nwItemClass) -> None:
        super().__init__(parent=parent)

        self._parent = parent
        self._class = itemClass
        self._treeMap: dict[str, QTreeWidgetItem] = {}

        iPx = SHARED.theme.baseIconHeight
        iSz = SHARED.theme.baseIconSize

        self.setHeaderLabels(
            [
                self.tr("Tag"),
                "",
                "",
                self.tr("Importance"),
                self.tr("Document"),
                self.tr("Heading"),
                self.tr("Short Description"),
            ]
        )
        self.setIndentation(0)
        self.setIconSize(iSz)
        self.setFrameStyle(QFrame.Shape.NoFrame)
        self.setSelectionMode(QAbstractItemView.SelectionMode.NoSelection)
        self.setExpandsOnDoubleClick(False)
        self.setDragEnabled(False)
        self.setSortingEnabled(True)
        self.sortByColumn(self.C_NAME, Qt.SortOrder.AscendingOrder)

        # Set Header Sizes
        if header := self.header():
            header.setStretchLastSection(True)
            header.setMinimumSectionSize(iPx + 6)  # See Issue #1627
            header.setSectionResizeMode(self.C_EDIT, QtHeaderFixed)
            header.setSectionResizeMode(self.C_VIEW, QtHeaderFixed)
            header.resizeSection(self.C_EDIT, iPx + 6)
            header.resizeSection(self.C_VIEW, iPx + 6)
            header.setSectionsMovable(False)

        # Cache Icons Locally
        self.updateTheme()

        # Signals
        self.clicked.connect(self._treeItemClicked)
        self.doubleClicked.connect(self._treeItemDoubleClicked)

    def updateTheme(self) -> None:
        """Update theme elements."""
        logger.debug("Theme Update: _ViewPanelKeyWords")

        self._classIcon = SHARED.theme.getIcon(nwLabels.CLASS_ICON[self._class], "root")
        self._editIcon = SHARED.theme.getIcon("edit", "change")
        self._viewIcon = SHARED.theme.getIcon("view", "action")

    def countEntries(self) -> int:
        """Return the number of items in the list."""
        return self.topLevelItemCount()

    def clearContent(self) -> None:
        """Clear the list."""
        self._treeMap = {}
        self.clear()

    def addUpdateEntry(self, tag: str, name: str, iItem: IndexNode, hItem: IndexHeading) -> None:
        """Add a new entry, or update an existing one."""
        nwItem = iItem.item
        impLabel, impIcon = nwItem.getImportStatus()
        iLevel = nwStyles.H_LEVEL.get(hItem.level, 0) if nwItem.isDocumentLayout() else 5
        hDec = SHARED.theme.getHeaderDecorationNarrow(iLevel)

        # This can not use a get call to the dictionary as that would create an
        # instance of the QTreeWidgetItem, which has some weird side effects
        trItem = self._treeMap[tag] if tag in self._treeMap else QTreeWidgetItem()

        trItem.setIcon(self.C_NAME, self._classIcon)
        trItem.setText(self.C_NAME, name)
        trItem.setToolTip(self.C_NAME, name)
        trItem.setIcon(self.C_EDIT, self._editIcon)
        trItem.setIcon(self.C_VIEW, self._viewIcon)
        trItem.setIcon(self.C_IMPORT, impIcon)
        trItem.setText(self.C_IMPORT, impLabel)
        trItem.setToolTip(self.C_IMPORT, impLabel)
        trItem.setIcon(self.C_DOC, nwItem.getMainIcon())
        trItem.setText(self.C_DOC, nwItem.itemName)
        trItem.setToolTip(self.C_DOC, nwItem.itemName)
        trItem.setData(self.C_TITLE, QtDecorationRole, hDec)
        trItem.setText(self.C_TITLE, hItem.title)
        trItem.setToolTip(self.C_TITLE, hItem.title)
        trItem.setText(self.C_SHORT, hItem.synopsis)
        trItem.setToolTip(self.C_SHORT, hItem.synopsis)
        trItem.setData(self.C_DATA, self.D_TAG, tag)

        if tag not in self._treeMap:
            self.addTopLevelItem(trItem)
            self._treeMap[tag] = trItem

    def removeEntry(self, tag: str) -> bool:
        """Remove a tag from the list."""
        if tag in self._treeMap:
            self.takeTopLevelItem(self.indexOfTopLevelItem(self._treeMap[tag]))
            self._treeMap.pop(tag, None)
            return True
        return False

    def setColumnWidths(self, widths: list[int]) -> None:
        """Set the column widths."""
        if isinstance(widths, list) and len(widths) >= 4:
            self.setColumnWidth(self.C_NAME, checkInt(widths[0], 100))
            self.setColumnWidth(self.C_IMPORT, checkInt(widths[1], 100))
            self.setColumnWidth(self.C_DOC, checkInt(widths[2], 100))
            self.setColumnWidth(self.C_TITLE, checkInt(widths[3], 100))

    def getColumnWidths(self) -> list[int]:
        """Get the widths of the user-adjustable columns."""
        return [
            self.columnWidth(self.C_NAME),
            self.columnWidth(self.C_IMPORT),
            self.columnWidth(self.C_DOC),
            self.columnWidth(self.C_TITLE),
        ]

    ##
    #  Private Slots
    ##

    @pyqtSlot("QModelIndex")
    def _treeItemClicked(self, index: QModelIndex) -> None:
        """Emit follow tag signal on user click."""
        tag = index.siblingAtColumn(self.C_DATA).data(self.D_TAG)
        if index.column() == self.C_EDIT:
            self._parent.loadDocumentTagRequest.emit(tag, nwDocMode.EDIT)
        elif index.column() == self.C_VIEW:
            self._parent.loadDocumentTagRequest.emit(tag, nwDocMode.VIEW)

    @pyqtSlot("QModelIndex")
    def _treeItemDoubleClicked(self, index: QModelIndex) -> None:
        """Emit follow tag signal on user double click."""
        tag = index.siblingAtColumn(self.C_DATA).data(self.D_TAG)
        if index.column() not in (self.C_EDIT, self.C_VIEW):
            self._parent.loadDocumentTagRequest.emit(tag, nwDocMode.VIEW)
