'''Tower Spotter - QGIS Plugin
Copyright (C) 2026 Vicky Sharma

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 2 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.'''

import os
import math
from qgis.PyQt.QtCore import QVariant
from qgis.PyQt.QtWidgets import QAction, QInputDialog, QMessageBox, QToolBar, QMenu
from qgis.core import *
from qgis.PyQt.QtGui import QFont, QColor, QIcon


class dynamicRouteChecker:

    def __init__(self, iface):
        self.iface = iface
        self.layer = None
        self.active = False
        self.point_layer = None
        self.segment_layer = None
        self.toolbar = None
        self.action = None
        self.menu_name = "Ineffable Tools"

    # ------------------ GUI ------------------ #

    def initGui(self):
        # 1. Setup icon and action
        icon_path = os.path.join(os.path.dirname(__file__), 'icon.png')
        self.action = QAction(
            QIcon(icon_path), 
            "Dynamic Route Checker", 
            self.iface.mainWindow()
        )
        self.action.setCheckable(True)
        self.action.toggled.connect(self.toggle)

        # 2. Add to "Ineffable Tools" menu
        main_menu = self.iface.mainWindow().menuBar()
        found_menu = None
        
        # Find existing "Ineffable Tools" menu
        for action in main_menu.actions():
            if action.text() == self.menu_name:
                found_menu = action.menu()
                break
        
        # Create it if it doesn't exist
        if not found_menu:
            found_menu = QMenu(self.menu_name, self.iface.mainWindow())
            main_menu.addMenu(found_menu)
            
        found_menu.addAction(self.action)

    def unload(self):
        # Remove action from menu
        main_menu = self.iface.mainWindow().menuBar()
        for action in main_menu.actions():
            if action.text() == self.menu_name:
                menu = action.menu()
                if menu:
                    menu.removeAction(self.action)
                break

    # ------------------ TOGGLE ------------------ #

    def toggle(self, state):
        if state:
            self.start()
        else:
            self.stop()

    # ------------------ START ------------------ #

    def start(self):

        layers = []
        for l in QgsProject.instance().mapLayers().values():
            if l.type() == QgsMapLayerType.VectorLayer and \
               l.geometryType() == QgsWkbTypes.LineGeometry:
                layers.append(l)

        if not layers:
            QMessageBox.critical(None, "Error", "No line layers found.")
            self.action.setChecked(False)
            return

        items = [l.name() for l in layers]
        name, ok = QInputDialog.getItem(
            None,
            "Select Line Layer",
            "Choose layer:",
            items,
            0,
            False
        )

        if not ok:
            self.action.setChecked(False)
            return

        self.layer = next(l for l in layers if l.name() == name)
        self.active = True

        self.create_layers()
        self.connect_signals()
        self.update_layers()

    # ------------------ STOP ------------------ #

    def stop(self):
        self.active = False
        self.disconnect_signals()

        if self.point_layer:
            QgsProject.instance().removeMapLayer(self.point_layer.id())
        if self.segment_layer:
            QgsProject.instance().removeMapLayer(self.segment_layer.id())

    # ------------------ SIGNALS ------------------ #

    def connect_signals(self):
        self.layer.geometryChanged.connect(self.update_layers)
        self.layer.featureAdded.connect(self.update_layers)
        self.layer.featureDeleted.connect(self.update_layers)

    def disconnect_signals(self):
        try:
            if self.layer:
                self.layer.geometryChanged.disconnect(self.update_layers)
                self.layer.featureAdded.disconnect(self.update_layers)
                self.layer.featureDeleted.disconnect(self.update_layers)
        except (TypeError, RuntimeError, AttributeError) as e:
            QgsMessageLog.logMessage(f"Signal disconnect ignored: {e}", "DynamicRouteChecker", Qgis.Info)

    # ------------------ MEMORY LAYERS ------------------ #

    def create_layers(self):

        self.point_layer = QgsVectorLayer(
            f"Point?crs={self.layer.crs().authid()}",
            "Dynamic_Vertex_Angles",
            "memory"
        )
        pr = self.point_layer.dataProvider()
        pr.addAttributes([QgsField("angle", QVariant.Double)])
        self.point_layer.updateFields()
        QgsProject.instance().addMapLayer(self.point_layer)

        self.segment_layer = QgsVectorLayer(
            f"LineString?crs={self.layer.crs().authid()}",
            "Dynamic_Segment_Length_m",
            "memory"
        )
        pr2 = self.segment_layer.dataProvider()
        pr2.addAttributes([QgsField("distance_m", QVariant.Double)])
        self.segment_layer.updateFields()
        QgsProject.instance().addMapLayer(self.segment_layer)

        self.setup_labels()

    # ------------------ LABELS ------------------ #

    def setup_labels(self):

        label = QgsPalLayerSettings()
        label.fieldName = "angle"
        label.placement = QgsPalLayerSettings.AroundPoint

        fmt = QgsTextFormat()
        fmt.setFont(QFont("Arial", 19))
        fmt.setSize(15)
        fmt.setColor(QColor("blue"))
        label.setFormat(fmt)

        self.point_layer.setLabeling(QgsVectorLayerSimpleLabeling(label))
        self.point_layer.setLabelsEnabled(True)

        seg_label = QgsPalLayerSettings()
        seg_label.fieldName = "distance_m"
        seg_label.placement = QgsPalLayerSettings.Line

        fmt2 = QgsTextFormat()
        fmt2.setFont(QFont("Arial", 19))
        fmt2.setSize(15)
        fmt2.setColor(QColor("red"))
        seg_label.setFormat(fmt2)

        self.segment_layer.setLabeling(QgsVectorLayerSimpleLabeling(seg_label))
        self.segment_layer.setLabelsEnabled(True)

    # ------------------ UPDATE ------------------ #

    def update_layers(self, *args):

        if not self.active:
            return

        self.point_layer.dataProvider().deleteFeatures(
            [f.id() for f in self.point_layer.getFeatures()])
        self.segment_layer.dataProvider().deleteFeatures(
            [f.id() for f in self.segment_layer.getFeatures()])

        point_feats = []
        seg_feats = []

        for feat in self.layer.getFeatures():
            geom = feat.geometry()
            crs = self.layer.crs()

            if crs.mapUnits() == QgsUnitTypes.DistanceMeters:
                geom_projected = QgsGeometry(geom)
                transform_to_utm = None
            else:
                center = geom.boundingBox().center()

                transform_to_wgs = QgsCoordinateTransform(
                    crs,
                    QgsCoordinateReferenceSystem("EPSG:4326"),
                    QgsProject.instance()
                )

                center_wgs = transform_to_wgs.transform(center)
                zone = int((center_wgs.x() + 180) / 6) + 1
                epsg = f"EPSG:326{zone:02d}" if center_wgs.y() >= 0 else f"EPSG:327{zone:02d}"

                utm_crs = QgsCoordinateReferenceSystem(epsg)

                transform_to_utm = QgsCoordinateTransform(
                    crs,
                    utm_crs,
                    QgsProject.instance()
                )

                geom_projected = QgsGeometry(geom)
                geom_projected.transform(transform_to_utm)

            vertices = geom_projected.asPolyline() if not geom_projected.isMultipart() else geom_projected.asMultiPolyline()[0]

            if len(vertices) < 2:
                continue

            for i in range(1, len(vertices) - 1):
                angle = self.calculate_angle(vertices[i - 1], vertices[i], vertices[i + 1])

                pt = vertices[i]
                if transform_to_utm:
                    pt = transform_to_utm.transform(pt, QgsCoordinateTransform.ReverseTransform)

                f = QgsFeature(self.point_layer.fields())
                f.setGeometry(QgsGeometry.fromPointXY(pt))
                f.setAttribute("angle", round(angle, 2))
                point_feats.append(f)

            for i in range(len(vertices) - 1):
                p1 = vertices[i]
                p2 = vertices[i + 1]
                dist = math.hypot(p2.x() - p1.x(), p2.y() - p1.y())

                if transform_to_utm:
                    p1 = transform_to_utm.transform(p1, QgsCoordinateTransform.ReverseTransform)
                    p2 = transform_to_utm.transform(p2, QgsCoordinateTransform.ReverseTransform)

                f2 = QgsFeature(self.segment_layer.fields())
                f2.setGeometry(QgsGeometry.fromPolylineXY([p1, p2]))
                f2.setAttribute("distance_m", round(dist, 2))
                seg_feats.append(f2)

        self.point_layer.dataProvider().addFeatures(point_feats)
        self.segment_layer.dataProvider().addFeatures(seg_feats)

        self.point_layer.updateExtents()
        self.segment_layer.updateExtents()
        self.point_layer.triggerRepaint()
        self.segment_layer.triggerRepaint()

    # ------------------ MATH ------------------ #

    def compute_azimuth(self, p1, p2):
        angle_rad = math.atan2(p2.y() - p1.y(), p2.x() - p1.x())
        angle_deg = math.degrees(angle_rad)
        return angle_deg if angle_deg >= 0 else angle_deg + 360

    def calculate_angle(self, p_prev, p_curr, p_next):
        incoming = self.compute_azimuth(p_prev, p_curr)
        outgoing = self.compute_azimuth(p_curr, p_next)
        diff = (outgoing - incoming + 180) % 360 - 180
        return abs(diff)