import os

import svgwrite
from svgwrite.shapes import Polyline

from dataclasses import Glyph, Metadata

base = 16
cap = -16
svg_size = 1024
guard = 12
line_style = {'fill': 'none', 'stroke': 'black', 'stroke-width': 0, 'stroke-linecap': 'round',
              'stroke-linejoin': 'round'}


def generate(glyph: Glyph, metadata: Metadata):
    print(f'Generating character \'{metadata.character}\' for font {metadata.font_name}')

    # Assumes font folder already exists
    font_path = os.path.join(os.getcwd(), 'svgs', metadata.font_name)

    left_side_bearing, right_side_bearing = _calculate_bearings(glyph)
    svg_filename = f'ascii{str(metadata.ascii_value)}_l{left_side_bearing}_r{right_side_bearing}.svg'
    dwg = svgwrite.Drawing(os.path.join(font_path, svg_filename), viewBox=f"0 0 {svg_size} {svg_size}")

    points = []
    for coordinate in glyph.coordinates:
        if coordinate:
            x, y = coordinate
            x = _map_to_svg(x)
            y = _map_to_svg(y)
            points.append((x, y))
        else:
            # Pen up
            # Always check if line is empty (i.e. points array is empty).
            # Empty lines can cause problems.
            if points:
                dwg.add(Polyline(points, **line_style))
            points = []

    # Finalize the drawing
    if points:
        dwg.add(Polyline(points, **line_style))

    dwg.save()


def _calculate_bearings(glyph: Glyph):
    if glyph.coordinates:
        leftmost_point = _map_to_svg(min(coordinate[0] for coordinate in glyph.coordinates if coordinate))
        rightmost_point = _map_to_svg(max(coordinate[0] for coordinate in glyph.coordinates if coordinate))
    else:
        leftmost_point = rightmost_point = _map_to_svg(0)

    left_side_bearing = leftmost_point - _map_to_svg(glyph.left)
    right_side_bearing = _map_to_svg(glyph.right) - rightmost_point
    return left_side_bearing, right_side_bearing


def _map_to_svg(x):
    # Scale proportionally (* svg_size / (base - cap))
    # Guard to avoid going out of bounds after stroking the character
    # Offset, since the SVG starts at zero (+ svg_size / 2)
    # Round because the font should only contain integers
    return x * (svg_size - 2 * guard) / (base - cap) + svg_size / 2