# -*- coding: utf-8 -*-

import math
from qgis.PyQt.QtCore import pyqtSignal, Qt
from qgis.PyQt.QtGui import QCursor
from qgis.gui import QgsMapToolEmitPoint
from qgis.core import QgsCoordinateReferenceSystem, QgsCoordinateTransform, QgsProject


# XYZ Tile Functions

def deg2tile(lat_deg, lon_deg, zoom):
    """Convert latitude/longitude to XYZ tile coordinates."""
    lat_rad = math.radians(lat_deg)
    n = 2.0 ** zoom
    x = int((lon_deg + 180.0) / 360.0 * n)
    y = int((1.0 - math.asinh(math.tan(lat_rad)) / math.pi) / 2.0 * n)
    return (x, y, zoom)


def tile2deg(x, y, zoom):
    """Convert XYZ tile coordinates to latitude/longitude (top-left corner)."""
    n = 2.0 ** zoom
    lon_deg = x / n * 360.0 - 180.0
    lat_rad = math.atan(math.sinh(math.pi * (1 - 2 * y / n)))
    lat_deg = math.degrees(lat_rad)
    return (lat_deg, lon_deg)


# UTM Projection Functions

def latlon_to_utm(lat, lon):
    """Convert latitude/longitude to UTM coordinates."""
    # Determine UTM zone
    zone = int((lon + 180) / 6) + 1

    # Handle special cases for Norway and Svalbard
    if 56.0 <= lat < 64.0 and 3.0 <= lon < 12.0:
        zone = 32
    elif 72.0 <= lat <= 84.0 and lon >= 0.0:
        if lon < 9.0:
            zone = 31
        elif lon < 21.0:
            zone = 33
        elif lon < 33.0:
            zone = 35
        elif lon < 42.0:
            zone = 37

    # UTM parameters
    a = 6378137.0  # WGS84 semi-major axis
    e_sq = 0.00669437999014  # WGS84 eccentricity squared
    k0 = 0.9996  # UTM scale factor

    lat_rad = math.radians(lat)
    lon_rad = math.radians(lon)
    lon_origin = math.radians((zone - 1) * 6 - 180 + 3)

    # UTM calculations
    N = a / math.sqrt(1 - e_sq * math.sin(lat_rad) ** 2)
    T = math.tan(lat_rad) ** 2
    C = e_sq * math.cos(lat_rad) ** 2 / (1 - e_sq)
    A = math.cos(lat_rad) * (lon_rad - lon_origin)

    M = a * ((1 - e_sq / 4 - 3 * e_sq**2 / 64 - 5 * e_sq**3 / 256) * lat_rad -
             (3 * e_sq / 8 + 3 * e_sq**2 / 32 + 45 * e_sq**3 / 1024) * math.sin(2 * lat_rad) +
             (15 * e_sq**2 / 256 + 45 * e_sq**3 / 1024) * math.sin(4 * lat_rad) -
             (35 * e_sq**3 / 3072) * math.sin(6 * lat_rad))

    x = k0 * N * (A + (1 - T + C) * A**3 / 6 + (5 - 18 * T + T **
                  2 + 72 * C - 58 * 0.0067394967) * A**5 / 120)
    y = k0 * (M + N * math.tan(lat_rad) * (A**2 / 2 + (5 - T + 9 * C + 4 * C**2) * A**4 / 24 +
                                           (61 - 58 * T + T**2 + 600 * C - 330 * 0.0067394967) * A**6 / 720))

    # Add false easting/northing
    x += 500000
    if lat < 0:
        y += 10000000

    hemisphere = 'N' if lat >= 0 else 'S'

    return zone, hemisphere, x, y


def utm_to_latlon(zone, hemisphere, x, y):
    """Convert UTM coordinates to latitude/longitude."""
    # UTM parameters
    a = 6378137.0  # WGS84 semi-major axis
    e_sq = 0.00669437999014  # WGS84 eccentricity squared
    k0 = 0.9996  # UTM scale factor

    # Remove false easting/northing
    x -= 500000
    if hemisphere == 'S':
        y -= 10000000

    lon_origin = math.radians((zone - 1) * 6 - 180 + 3)

    # Calculate meridional arc
    M = y / k0
    mu = M / (a * (1 - e_sq / 4 - 3 * e_sq**2 / 64 - 5 * e_sq**3 / 256))

    e1 = (1 - math.sqrt(1 - e_sq)) / (1 + math.sqrt(1 - e_sq))
    J1 = (3 * e1 / 2 - 27 * e1**3 / 32)
    J2 = (21 * e1**2 / 16 - 55 * e1**4 / 32)
    J3 = (151 * e1**3 / 96)
    J4 = (1097 * e1**4 / 512)

    fp = mu + J1 * math.sin(2 * mu) + J2 * math.sin(4 * mu) + \
        J3 * math.sin(6 * mu) + J4 * math.sin(8 * mu)

    e1_sq = e_sq / (1 - e_sq)
    C1 = e1_sq * math.cos(fp)**2
    T1 = math.tan(fp)**2
    N1 = a / math.sqrt(1 - e_sq * math.sin(fp)**2)
    R1 = a * (1 - e_sq) / (1 - e_sq * math.sin(fp)**2)**1.5
    D = x / (N1 * k0)

    lat = (fp - (N1 * math.tan(fp) / R1) * (D**2 / 2 - (5 + 3 * T1 + 10 * C1 - 4 * C1**2 - 9 * e1_sq) * D**4 / 24 +
                                            (61 + 90 * T1 + 298 * C1 + 45 * T1**2 - 252 * e1_sq - 3 * C1**2) * D**6 / 720))
    lon = lon_origin + (D - (1 + 2 * T1 + C1) * D**3 / 6 + (5 - 2 * C1 + 28 *
                        T1 - 3 * C1**2 + 8 * e1_sq + 24 * T1**2) * D**5 / 120) / math.cos(fp)

    return math.degrees(lat), math.degrees(lon)


# CORRECTED MGRS Functions

def get_mgrs_grid_designator(lat):
    """Get MGRS grid zone designator letter from latitude - FIXED."""
    if lat >= 84:
        return None
    elif lat >= 72:
        return 'X'
    elif lat >= 64:
        return 'W'
    elif lat >= 56:
        return 'V'
    elif lat >= 48:
        return 'U'
    elif lat >= 40:
        return 'T'
    elif lat >= 32:
        return 'S'
    elif lat >= 24:
        return 'R'
    elif lat >= 16:
        return 'Q'
    elif lat >= 8:
        return 'P'
    elif lat >= 0:
        return 'N'
    elif lat >= -8:
        return 'M'
    elif lat >= -16:
        return 'L'
    elif lat >= -24:
        return 'K'
    elif lat >= -32:
        return 'J'
    elif lat >= -40:
        return 'H'
    elif lat >= -48:
        return 'G'
    elif lat >= -56:
        return 'F'
    elif lat >= -64:
        return 'E'
    elif lat >= -72:
        return 'D'
    elif lat >= -80:
        return 'C'
    else:
        return None


def get_mgrs_100km_square_id(utm_zone, utm_x, utm_y):
    """Get MGRS 100km square identifier - CORRECTED."""

    # Column letters - pattern repeats every 3 zones
    col_letters_sets = [
        'ABCDEFGH',    # Zones 1, 4, 7, 10, etc.
        'JKLMNPQR',    # Zones 2, 5, 8, 11, etc.
        'STUVWXYZ'     # Zones 3, 6, 9, 12, etc.
    ]

    # Determine which column letter set to use based on zone
    col_set_index = (utm_zone - 1) % 3
    col_letters = col_letters_sets[col_set_index]

    # Calculate column index based on easting
    # Adjusted for proper offset
    col_index = int((utm_x - 500000 + 400000) / 100000)
    col_index = max(0, min(7, col_index))  # Clamp to valid range

    col_letter = col_letters[col_index]

    # Row letters - alternating pattern based on zone number
    if utm_zone % 2 == 1:  # Odd zones
        row_letters = 'ABCDEFGHJKLMNPQRSTUV'
    else:  # Even zones
        row_letters = 'FGHJKLMNPQRSTUVABCDE'

    # Calculate row index based on northing
    row_index = int(utm_y / 100000) % 20
    row_letter = row_letters[row_index]

    return col_letter + row_letter


def latlon_to_mgrs(lat, lon, precision=0):
    """
    Convert latitude/longitude to MGRS coordinate string - FIXED.
    """
    try:
        # Get UTM coordinates
        zone, hemisphere, x, y = latlon_to_utm(lat, lon)

        # Get grid zone designator
        grid_designator = get_mgrs_grid_designator(lat)
        if grid_designator is None:
            print(f"No grid designator for lat {lat}")
            return None

        # Get 100km square identifier
        square_id = get_mgrs_100km_square_id(zone, x, y)

        # Create base MGRS reference (GZD + 100km square)
        base_mgrs = f"{zone:02d}{grid_designator}{square_id}"

        print(
            f"MGRS generation: lat={lat:.6f}, lon={lon:.6f} -> Zone={zone}, Grid={grid_designator}, Square={square_id}, Result={base_mgrs}")

        # Return just the 100km square reference if precision is 0
        if precision == 0:
            return base_mgrs

        # Calculate grid coordinates within 100km square for higher precision
        grid_x = int(x % 100000)
        grid_y = int(y % 100000)

        # Format coordinates based on precision
        coord_format = f"{{:0{precision}d}}"
        scale = 10 ** (5 - precision)
        grid_x_scaled = grid_x // scale
        grid_y_scaled = grid_y // scale
        coord_str = coord_format.format(
            grid_x_scaled) + coord_format.format(grid_y_scaled)

        return base_mgrs + coord_str

    except Exception as e:
        print(f"Error converting to MGRS: {e}")
        import traceback
        traceback.print_exc()
        return None


# def mgrs_to_latlon(mgrs_string):
#     """Convert MGRS coordinate string to latitude/longitude - COMPLETELY FIXED."""
#     try:
#         mgrs = mgrs_string.strip().upper()
#         print(f"Converting MGRS: {mgrs}")

#         # Parse MGRS string
#         if len(mgrs) < 5:
#             print(f"MGRS string too short: {mgrs}")
#             return None

#         # Extract zone number (first 2 digits)
#         zone = int(mgrs[:2])

#         # Extract grid zone designator (3rd character)
#         grid_designator = mgrs[2]

#         # Extract 100km square identifier (4th and 5th characters)
#         square_id = mgrs[3:5]

#         print(f"Zone: {zone}, Grid: {grid_designator}, Square: {square_id}")

#         # Extract coordinates (everything after position 5)
#         coord_part = mgrs[5:]

#         # For 100km square only (no numerical coordinates)
#         if len(coord_part) == 0:
#             # Return center of 100km square
#             grid_x = 50000  # Center of square
#             grid_y = 50000
#         else:
#             if len(coord_part) % 2 != 0:
#                 return None

#             precision = len(coord_part) // 2
#             x_str = coord_part[:precision]
#             y_str = coord_part[precision:]

#             # Scale coordinates
#             scale = 10 ** (5 - precision)
#             grid_x = int(x_str) * scale
#             grid_y = int(y_str) * scale

#         # Get hemisphere from grid designator
#         hemisphere = 'N' if grid_designator >= 'N' else 'S'

#         # Calculate base UTM coordinates for the 100km square
#         col_letters_sets = [
#             'ABCDEFGH',    # Zones 1, 4, 7, 10, etc.
#             'JKLMNPQR',    # Zones 2, 5, 8, 11, etc.
#             'STUVWXYZ'     # Zones 3, 6, 9, 12, etc.
#         ]

#         col_set_index = (zone - 1) % 3
#         col_letters = col_letters_sets[col_set_index]

#         try:
#             col_index = col_letters.index(square_id[0])
#         except ValueError:
#             print(f"Invalid column letter: {square_id[0]}")
#             return None

#         # Calculate base X coordinate
# base_x = 500000 + (col_index - 4) * 100000  # 500000 is false easting,
# adjust for central column

#         # Row calculation
#         if zone % 2 == 1:
#             row_letters = 'ABCDEFGHJKLMNPQRSTUV'
#         else:
#             row_letters = 'FGHJKLMNPQRSTUVABCDE'

#         try:
#             row_index = row_letters.index(square_id[1])
#         except ValueError:
#             print(f"Invalid row letter: {square_id[1]}")
#             return None

#         # Calculate base Y coordinate
#         base_y = row_index * 100000

#         # Final UTM coordinates
#         utm_x = base_x + grid_x
#         utm_y = base_y + grid_y

#         print(f"UTM: Zone {zone}{hemisphere}, X: {utm_x}, Y: {utm_y}")

#         # Convert UTM to lat/lon
#         lat, lon = utm_to_latlon(zone, hemisphere, utm_x, utm_y)

#         print(f"Result: Lat {lat:.6f}, Lon {lon:.6f}")
#         return lat, lon

#     except Exception as e:
#         print(f"Error converting from MGRS: {e}")
#         import traceback
#         traceback.print_exc()
#         return None
def mgrs_to_latlon(mgrs_string):
    """Convert MGRS coordinate string to latitude/longitude - COMPLETELY FIXED."""
    try:
        mgrs = mgrs_string.strip().upper()
        print(f"Converting MGRS: {mgrs}")

        # Parse MGRS string
        if len(mgrs) < 5:
            print(f"MGRS string too short: {mgrs}")
            return None

        # Extract zone number (first 2 digits)
        zone = int(mgrs[:2])

        # Extract grid zone designator (3rd character)
        grid_designator = mgrs[2]

        # Extract 100km square identifier (4th and 5th characters)
        square_id = mgrs[3:5]

        print(f"Zone: {zone}, Grid: {grid_designator}, Square: {square_id}")

        # Extract coordinates (everything after position 5)
        coord_part = mgrs[5:]

        # For 100km square only (no numerical coordinates)
        if len(coord_part) == 0:
            # Return center of 100km square
            grid_x = 50000  # Center of square
            grid_y = 50000
        else:
            if len(coord_part) % 2 != 0:
                return None

            precision = len(coord_part) // 2
            x_str = coord_part[:precision]
            y_str = coord_part[precision:]

            # Scale coordinates
            scale = 10 ** (5 - precision)
            grid_x = int(x_str) * scale
            grid_y = int(y_str) * scale

        # Get hemisphere from grid designator
        hemisphere = 'N' if grid_designator >= 'N' else 'S'

        # Calculate base UTM coordinates for the 100km square
        col_letters_sets = [
            'ABCDEFGH',    # Zones 1, 4, 7, 10, etc.
            'JKLMNPQR',    # Zones 2, 5, 8, 11, etc.
            'STUVWXYZ'     # Zones 3, 6, 9, 12, etc.
        ]

        col_set_index = (zone - 1) % 3
        col_letters = col_letters_sets[col_set_index]

        try:
            col_index = col_letters.index(square_id[0])
        except ValueError:
            print(f"Invalid column letter: {square_id[0]}")
            return None

        # Calculate base X coordinate
        base_x = 500000 + (col_index - 4) * 100000  # 500000 is false easting

        # Row calculation with 2,000,000m cycle handling
        if zone % 2 == 1:  # Odd zones
            row_letters = 'ABCDEFGHJKLMNPQRSTUV'
        else:  # Even zones
            row_letters = 'FGHJKLMNPQRSTUVABCDE'

        try:
            row_index = row_letters.index(square_id[1])
        except ValueError:
            print(f"Invalid row letter: {square_id[1]}")
            return None

        # Calculate base Y within 0-2,000,000m cycle
        base_y_in_cycle = row_index * 100000

        # Get expected latitude range for this band
        lat_band_ranges = {
            'C': (-80, -72), 'D': (-72, -64), 'E': (-64, -56), 'F': (-56, -48),
            'G': (-48, -40), 'H': (-40, -32), 'J': (-32, -24), 'K': (-24, -16),
            'L': (-16, -8), 'M': (-8, 0),
            'N': (0, 8), 'P': (8, 16), 'Q': (16, 24), 'R': (24, 32),
            'S': (32, 40), 'T': (40, 48), 'U': (48, 56), 'V': (56, 64),
            'W': (64, 72), 'X': (72, 84)
        }

        expected_lat_range = lat_band_ranges.get(grid_designator)
        if expected_lat_range is None:
            print(f"Invalid grid designator: {grid_designator}")
            return None

        # Try different 2,000,000m cycles to find the correct one
        # that produces a latitude within the expected band
        best_result = None
        best_lat_error = float('inf')

        for cycle in range(0, 10):  # Try up to 10 cycles (0-20,000,000m)
            test_base_y = base_y_in_cycle + (cycle * 2000000)

            # For southern hemisphere, adjust
            if hemisphere == 'S':
                test_base_y = 10000000 - test_base_y

            # Final UTM coordinates
            utm_x = base_x + grid_x
            utm_y = test_base_y + grid_y

            # Convert to lat/lon
            try:
                lat, lon = utm_to_latlon(zone, hemisphere, utm_x, utm_y)

                # Check if latitude is in expected range
                lat_min, lat_max = expected_lat_range
                if lat_min <= lat <= lat_max:
                    print(
                        f"Found match: Cycle {cycle}, UTM Y: {utm_y}, Lat: {lat:.6f}, Lon: {lon:.6f}")
                    return lat, lon

                # Track closest match in case exact match not found
                lat_center = (lat_min + lat_max) / 2
                lat_error = abs(lat - lat_center)
                if lat_error < best_lat_error:
                    best_lat_error = lat_error
                    best_result = (lat, lon, utm_y, cycle)

            except Exception as e: # nosec B112
                continue

        # If no exact match, use the closest one
        if best_result:
            lat, lon, utm_y, cycle = best_result
            print(
                f"Using closest match: Cycle {cycle}, UTM Y: {utm_y}, Lat: {lat:.6f}, Lon: {lon:.6f}")
            return lat, lon

        print(f"Failed to find valid conversion for {mgrs_string}")
        return None

    except Exception as e:
        print(f"Error converting from MGRS: {e}")
        import traceback
        traceback.print_exc()
        return None


def get_mgrs_grid_bounds_enhanced(mgrs_string):
    """Enhanced MGRS bounds calculation."""
    try:
        # Get center point
        result = mgrs_to_latlon(mgrs_string)
        if result is None:
            return None

        center_lat, center_lon = result

        # Determine grid size based on precision
        coord_part = mgrs_string[5:] if len(mgrs_string) > 5 else ""

        if len(coord_part) == 0:
            # 100km square
            grid_size = 100000
        else:
            precision = len(coord_part) // 2
            grid_size = 10 ** (5 - precision)

        # Convert to approximate degrees
        lat_deg_per_meter = 1 / 111320.0
        lon_deg_per_meter = 1 / (111320.0 * math.cos(math.radians(center_lat)))

        lat_offset = grid_size * lat_deg_per_meter / 2
        lon_offset = grid_size * lon_deg_per_meter / 2

        min_lat = center_lat - lat_offset
        max_lat = center_lat + lat_offset
        min_lon = center_lon - lon_offset
        max_lon = center_lon + lon_offset

        return min_lat, min_lon, max_lat, max_lon

    except Exception as e:
        print(f"Error getting enhanced MGRS bounds: {e}")
        return None


# Keep the get_mgrs_grid_bounds function for backward compatibility
get_mgrs_grid_bounds = get_mgrs_grid_bounds_enhanced


# Map Tool Class

class XYZMapTool(QgsMapToolEmitPoint):
    """Custom map tool for capturing XYZ/MGRS coordinates from canvas clicks."""

    # system, param1, param2, param3
    coordinates_clicked = pyqtSignal(str, object, object, object)

    def __init__(self, canvas, dock_widget=None):
        super(XYZMapTool, self).__init__(canvas)
        self.canvas = canvas
        self.dock_widget = dock_widget
        self.cursor = QCursor()

    def set_dock_widget(self, dock_widget):
        """Set the dock widget reference after initialization."""
        self.dock_widget = dock_widget

    def activate(self):
        """Called when the map tool is activated."""
        self.canvas.setCursor(QCursor(Qt.CursorShape.CrossCursor))

    def deactivate(self):
        """Called when the map tool is deactivated."""
        self.canvas.unsetCursor()

    def canvasReleaseEvent(self, event):
        """Handle mouse release events on the canvas."""
        # Get clicked point in map coordinates
        point = self.toMapCoordinates(event.pos())

        # Transform to WGS84 if needed
        map_crs = self.canvas.mapSettings().destinationCrs()
        wgs84_crs = QgsCoordinateReferenceSystem("EPSG:4326")

        if map_crs != wgs84_crs:
            transform = QgsCoordinateTransform(
                map_crs, wgs84_crs, QgsProject.instance())
            try:
                wgs84_point = transform.transform(point)
                lat, lon = wgs84_point.y(), wgs84_point.x()
            except Exception as e:
                print(f"Error transforming coordinates: {e}")
                return
        else:
            lat, lon = point.y(), point.x()

        if not self.dock_widget:
            return

        current_system = self.dock_widget.get_current_system()

        if current_system == "XYZ Tiles":
            # Get current Z value from dock widget
            current_z = self.dock_widget.z_input.value() if hasattr(
                self.dock_widget, 'z_input') else 14
            x, y, z = deg2tile(lat, lon, current_z)
            self.coordinates_clicked.emit("XYZ", x, y, z)

        elif current_system == "MGRS":
            # Convert to MGRS with precision=0 (100km square only)
            mgrs_ref = latlon_to_mgrs(lat, lon, precision=0)
            if mgrs_ref:
                self.coordinates_clicked.emit("MGRS", mgrs_ref, None, None)
                print(
                    f"Generated MGRS: {mgrs_ref} from lat/lon: {lat:.6f}, {lon:.6f}")
            else:
                print(f"Failed to convert lat/lon {lat}, {lon} to MGRS")
