"""
    To be used in Python 3.6+ due to dependencies
"""
from copy import copy
import random
import string
import os
import numpy as np
from scipy.spatial.transform import Rotation as R

# Correct dependencies on Win
# https://stackoverflow.com/questions/46265677/get-cairosvg-working-in-windows
if 'Windows' in os.environ.get('OS',''):
    dir_path = os.path.dirname(os.path.realpath(__file__))
    os.environ['path'] += f';{os.path.abspath(dir_path + "/cairo_dlls/")}'

import cairosvg
import svgpathtools as svgpath
import svgwrite as sw

import matplotlib.pyplot as plt

# my
from pygarment import data_config
from . import core
from .utils import *


class VisPattern(core.ParametrizedPattern):
    """
        "Visualizible" pattern wrapper of pattern specification in custom JSON format.
        Input:
            * Pattern template in custom JSON format
        Output representations: 
            * Pattern instance in custom JSON format 
                * In the current state
            * SVG (stitching info is lost)
            * PNG for visualization
        
        Not implemented: 
            * Support for patterns with darts

        NOTE: Visualization assumes the pattern uses cm as units
    """

    # ------------ Interface -------------

    def __init__(self, pattern_file=None):
        super().__init__(pattern_file)

        self.px_per_unit = 3

    def serialize(
            self, path, to_subfolder=True, tag='', 
            with_3d=True, with_text=True, view_ids=True, 
            with_printable=False,
            empty_ok=False):

        log_dir = super().serialize(path, to_subfolder, tag=tag, empty_ok=empty_ok)
        if len(self.panel_order()) == 0:  # If we are still here, but pattern is empty, don't generate an image
            return log_dir

        if tag:
            tag = '_' + tag
        svg_file = os.path.join(log_dir, (self.name + tag + '_pattern.svg'))
        svg_printable_file = os.path.join(log_dir, (self.name + tag + '_print_pattern.svg'))
        png_file = os.path.join(log_dir, (self.name + tag + '_pattern.png')) 
        pdf_file = os.path.join(log_dir, (self.name + tag + '_print_pattern.pdf')) 
        png_3d_file = os.path.join(log_dir, (self.name + tag + '_3d_pattern.png'))

        # save visualtisation
        self._save_as_image(svg_file, png_file, with_text, view_ids)
        if with_3d:
            self._save_as_image_3D(png_3d_file)
        if with_printable:
            self._save_as_pdf(svg_printable_file, pdf_file, with_text, view_ids)

        return log_dir

    # -------- Drawing ---------

    def _verts_to_px_coords(self, vertices, translation_2d):
        """Convert given vertices and panel (2D) translation to px coordinate frame & units"""
        # Flip Y coordinate (in SVG Y looks down)
        vertices[:, 1] *= -1
        translation_2d[1] *= -1
        # Put upper left corner of the bounding box at zero
        offset = np.min(vertices, axis=0)
        vertices = vertices - offset
        translation_2d = translation_2d + offset
        return vertices, translation_2d

    def _flip_y(self, point):
        """
            To get to image coordinates one might need to flip Y axis
        """
        flipped_point = list(point)  # top-level copy
        flipped_point[1] *= -1
        return flipped_point

    def _draw_a_panel(self, panel_name, apply_transform=True, fill=True):
        """
        Adds a requested panel to the svg drawing with given offset and scaling
        Assumes (!!) 
            that edges are correctly oriented to form a closed loop
        Returns 
            the lower-right vertex coordinate for the convenice of future offsetting.
        """
        attributes = {
            'fill':  'rgb(115, 113, 125)' if fill else 'rgb(255,255,255)',    # fill with white
            'stroke': 'rgb(51,51,51)', 
            'stroke-width': '0.2'
        }

        panel = self.pattern['panels'][panel_name]
        vertices = np.asarray(panel['vertices'])
        vertices, translation = self._verts_to_px_coords(
            vertices, 
            np.array(panel['translation'][:2]))   # Only XY

        # draw edges
        segs = [self._edge_as_curve(vertices, edge) for edge in panel['edges']]
        path = svgpath.Path(*segs)
        if apply_transform:
            # Placement and rotation according to the 3D location
            # But flatterened on 2D
            # Z-fist rotation to only reflect rotation visible in XY plane
            # NOTE: Heuristic, might be bug-prone
            rotation = R.from_euler('XYZ', panel['rotation'], degrees=True)   # XYZ

            # Estimate degree of rotation of Y axis
            # NOTE: Ox sometimes gets flipped because of 
            # Gimbal locks of this Euler angle representation
            res = rotation.apply([0, 1, 0])
            flat_rot_angle = np.rad2deg(vector_angle([0, 1], res[:2]))
            path = path.rotated(
                degs=-flat_rot_angle, 
                origin=list_to_c(vertices[0])
            )
            path = path.translated(list_to_c(translation))  # NOTE: rot/transl order is important!

        return path, attributes, panel['translation'][-1] >= 0

    def _add_panel_annotations(
            self, drawing, panel_name, path:svgpath.Path, with_text=True, view_ids=True):
        """ Adds a annotations for requested panel to the svg drawing with given offset and scaling
        Assumes (!!) 
            that edges are correctly oriented to form a closed loop
        Returns 
            the lower-right vertex coordinate for the convenice of future offsetting.
        """
        bbox = path.bbox()
        panel_center = np.array([(bbox[0] + bbox[1]) / 2, (bbox[2] + bbox[3]) / 2])
        
        if with_text:
            text_insert = panel_center   # + np.array([-len(panel_name) * 12 / 2, 3])
            drawing.add(drawing.text(panel_name, insert=text_insert, 
                        fill='rgb(31,31,31)', 
                        font_size='7', 
                        text_anchor='middle', 
                        dominant_baseline='middle'))

        if view_ids:
            # name vertices 
            for idx in range(len(path)):
                seg = path[idx]
                ver = c_to_np(seg.start)
                drawing.add(
                    drawing.text(str(idx), insert=ver, 
                                 fill='rgb(245,96,66)', 
                                 font_size='7'))
            # name edges
            for idx in range(len(path)):
                seg = path[idx]
                middle = c_to_np(seg.point(seg.ilength(seg.length() / 2, s_tol=1e-3)))
                middle[1] -= 3  # slightly above the line
                # name
                drawing.add(
                    drawing.text(idx, insert=middle, 
                                 fill='rgb(44,131,68)', 
                                 font_size='7', 
                                 text_anchor='middle'))

    def get_svg(self, svg_filename,
            with_text=True, view_ids=True, 
            flat=False, fill_panels=True,
            margin=2) -> sw.Drawing:
        """Convert pattern to writable svg representation"""

        if len(self.panel_order()) == 0:  # If we are still here, but pattern is empty, don't generate an image
            raise core.EmptyPatternError()
        
        # Get svg representation per panel
        # Order by depth (=> most front panels render in front)
        # TODOLOW Even smarter way is needed for prettier allignment
        panel_order = self.panel_order()
        panel_z = [self.pattern['panels'][pn]['translation'][-1] for pn in panel_order]
        z_sorted_panels = [p for _, p in sorted(zip(panel_z, panel_order))]

        # Get panel paths
        paths_front, paths_back = [], []
        attributes_f, attributes_b = [], []
        names_f, names_b = [], []
        shift_x_front, shift_x_back = margin, margin
        for panel in z_sorted_panels:
            if panel is not None:
                path, attr, front = self._draw_a_panel(
                    panel, 
                    apply_transform=not flat, 
                    fill=fill_panels
                )
                if flat:
                    path = path.translated(list_to_c([
                        shift_x_front if front else shift_x_back, 
                        0]))
                    bbox = path.bbox()
                    diff = (bbox[1] - bbox[0]) + margin
                    if front:
                        shift_x_front += diff
                    else:
                        shift_x_back += diff
                if front:
                    paths_front.append(path) 
                    attributes_f.append(attr) 
                    names_f.append(panel)
                else:
                    paths_back.append(path)
                    attributes_b.append(attr)
                    names_b.append(panel)

        # Shift back panels if both front and back exist
        if len(paths_front) > 0 and len(paths_back) > 0:
            front_max_x = max([path.bbox()[1] for path in paths_front]) 
            back_min_x = min([path.bbox()[0] for path in paths_back]) 
            shift_x = front_max_x - back_min_x + 10   # A little spacing
            if flat:
                front_max_y = max([path.bbox()[3] for path in paths_front]) 
                back_min_y = min([path.bbox()[2] for path in paths_back]) 
                shift_y = front_max_y - back_min_y + 10   # A little spacing
                shift_x = 0
            else:
                shift_y = 0
            paths_back = [path.translated(list_to_c([shift_x, shift_y])) for path in paths_back]
        
        # SVG convert
        paths = paths_front + paths_back
        arrdims = np.array([path.bbox() for path in paths])
        dims = np.max(arrdims[:, 1]) - np.min(arrdims[:, 0]), np.max(arrdims[:, 3]) - np.min(arrdims[:, 2])

        viewbox = (
            np.min(arrdims[:, 0]) - margin, 
            np.min(arrdims[:, 2]) - margin, 
            dims[0] + 2 * margin, 
            dims[1] + 2 * margin
        )

        # Pattern info for correct placement 
        self.svg_bbox = [np.min(arrdims[:, 0]), np.max(arrdims[:, 1]), np.min(arrdims[:, 2]), np.max(arrdims[:, 3])]
        self.svg_bbox_size = [viewbox[2], viewbox[3]]

        # Save
        attributes = attributes_f + attributes_b

        dwg = svgpath.wsvg(
            paths, 
            attributes=attributes, 
            margin_size=0,
            filename=svg_filename, 
            viewbox=viewbox, 
            dimensions=[str(viewbox[2]) + 'cm', str(viewbox[3]) + 'cm'],
            paths2Drawing=True)

        # text annotations
        panel_names = names_f + names_b
        if with_text or view_ids:
            for i, panel in enumerate(panel_names):
                if panel is not None:
                    self._add_panel_annotations(
                        dwg, panel, paths[i], with_text, view_ids)
        
        return dwg

    def _save_as_image(
            self, svg_filename, png_filename,
            with_text=True, view_ids=True, 
            margin=2):  
        """
            Saves current pattern in svg and png format for visualization

            * with_text: include panel names
            * view_ids: include ids of vertices and edges in the output image
            * margin: small amount of free space around the svg drawing (to correctly display the line width)

        """
        
        dwg = self.get_svg(
            svg_filename, 
            with_text=with_text, 
            view_ids=view_ids, 
            flat=False,
            margin=margin
        )
        
        dwg.save(pretty=True)

        # to png
        # NOTE: Assuming the pattern uses cm
        # 3 px == 1 cm
        # DPI = 96 (default) px/inch == 96/2.54 px/cm
        cairosvg.svg2png(
            url=svg_filename, write_to=png_filename, dpi=2.54*self.px_per_unit)
        
    def _save_as_image_3D(self, png_filename):
        """Save the patterns with 3D positioning using matplotlib visualization"""

        # NOTE: this routine is mostly needed for debugging

        fig = plt.figure(figsize=(30 / 2.54, 30 / 2.54))
        ax = fig.add_subplot(projection='3d')


        # TODOLOW Support arcs / curves (use linearization)
        for panel in self.pattern['panels']:
            p = self.pattern['panels'][panel]
            rot = p['rotation']
            tr = p['translation']
            verts_2d = p['vertices']

            verts_to_plot = copy(verts_2d)
            verts_to_plot.append(verts_to_plot[0])

            verts3d = np.vstack(tuple([self._point_in_3D(v, rot, tr) for v in verts_to_plot]))
            x = np.squeeze(np.asarray(verts3d[:, 0]))
            y = np.squeeze(np.asarray(verts3d[:, 1]))
            z = np.squeeze(np.asarray(verts3d[:, 2]))

            ax.plot(x, y, z)

        ax.view_init(elev=115, azim=-59, roll=30)
        ax.set_aspect('equal')
        fig.savefig(png_filename, dpi=300, transparent=False)

        plt.close(fig)  # Cleanup

    def _save_as_pdf(self, svg_filename, pdf_filename,
            with_text=True, view_ids=True, 
            margin=2):
        """Save a pattern as a pdf with non-overlapping panels and no filling 
            Suitable for printing
        """
        dwg = self.get_svg(
            svg_filename, 
            with_text=with_text, 
            view_ids=view_ids, 
            flat=True,
            fill_panels=False,
            margin=margin
        )
        dwg.save(pretty=True)

        # to pdf
        # NOTE: Assuming the pattern uses cm
        # 3 px == 1 cm
        # DPI = 96 (default) px/inch == 96/2.54 px/cm
        cairosvg.svg2pdf(
            url=svg_filename, write_to=pdf_filename, dpi=2.54*self.px_per_unit)

class RandomPattern(VisPattern):
    """
        Parameter randomization of a pattern template in custom JSON format.
        Input:
            * Pattern template in custom JSON format
        Output representations: 
            * Pattern instance in custom JSON format 
                (with updated parameter values and vertex positions)
            * SVG (stitching info is lost)
            * PNG for visualization

        Implementation limitations: 
            * Parameter randomization is only performed once on loading
            * Only accepts unchanged template files (all parameter values = 1) 
            otherwise, parameter values will go out of control and outside of the original range
            (with no way to recognise it)
    """

    # ------------ Interface -------------
    def __init__(self, template_file):
        """Note that this class requires some input file: 
            there is not point of creating this object with empty pattern"""
        super().__init__(template_file, view_ids=False)  # don't show ids for datasets

        # update name for a random pattern
        self.name = self.name + '_' + self._id_generator()

        # randomization setup
        self._randomize_pattern()

    # -------- Other Utils ---------
    def _id_generator(self, size=10,
                      chars=string.ascii_uppercase + string.digits):
        """Generated a random string of a given size, see
        https://stackoverflow.com/questions/2257441/random-string-generation-with-upper-case-letters-and-digits
        """
        return ''.join(random.choices(chars, k=size))
