import os
from dataclasses import dataclass, KW_ONLY
from collections.abc import Iterator
from reportlab.pdfgen import canvas
from reportlab.lib.pagesizes import LETTER, A4
from reportlab.lib.units import inch
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont
from reportlab.lib.units import mm

# Usage:
#   label = AveryLabels.AveryLabel(5160)
#   label.open( "labels5160.pdf" )
#   label.render( RenderAddress, 30 )
#   label.close()
#
# 'render' can either pass a callable, which receives the canvas object
# (with X,Y=0,0 at the lower right) or a string "form" name of a form
# previously created with canv.beginForm().

@dataclass
class LabelInfo:
    """Class for modeling label info"""
    _: KW_ONLY
    labels_horizontal: int
    labels_vertical: int
    label_size: tuple[float, float]
    gutter_size: tuple[float, float]
    margin: tuple[float, float]
    pagesize: tuple[float, float]

labelInfo: dict[str, LabelInfo] = {
    "averyL4731": LabelInfo(labels_horizontal= 7, labels_vertical= 27, label_size= (25.4*mm, 10*mm), gutter_size= (2.5*mm, 0), margin= (9*mm, 13.5*mm), pagesize= A4),
    # 2.6 x 1 address labels
    "avery5160": LabelInfo(labels_horizontal=  3, labels_vertical= 10, label_size= (187,  72), gutter_size= (11, 0), margin= (14, 36), pagesize= LETTER),
    "avery5161": LabelInfo(labels_horizontal=  2, labels_vertical= 10, label_size= (288,  72), gutter_size= (0, 0), margin= (18, 36), pagesize= LETTER),
    # 4 x 2 address labels
    "avery5163": LabelInfo(labels_horizontal=  2, labels_vertical=  5, label_size= (288, 144), gutter_size= (0, 0), margin= (18, 36), pagesize= LETTER),
    # 1.75 x 0.5 return address labels
    "avery5167": LabelInfo(labels_horizontal=  4, labels_vertical= 20, label_size= (126,  36), gutter_size= (0, 0), margin= (54, 36), pagesize= LETTER),
    # 3.5 x 2 business cards
    "avery5371": LabelInfo(labels_horizontal=  2, labels_vertical=  5, label_size= (252, 144), gutter_size= (0, 0), margin= (54, 36), pagesize= LETTER),
}

RETURN_ADDRESS = 5167
BUSINESS_CARDS = 5371

class AveryLabel:

    def __init__(self, label, **kwargs):
        data = labelInfo[label]
        self.across = data.labels_horizontal
        self.down = data.labels_vertical
        self.size = data.label_size
        self.labelsep = self.size[0]+data.gutter_size[0], self.size[1]+data.gutter_size[1]
        self.margins = data.margin
        self.topDown = True
        self.debug = False
        self.pagesize = data.pagesize
        self.position = 0
        self.__dict__.update(kwargs)

    def open(self, filename):
        self.canvas = canvas.Canvas( filename, pagesize=self.pagesize )
        if self.debug:
            self.canvas.setPageCompression( 0 )
        self.canvas.setLineJoin(1)
        self.canvas.setLineCap(1)

    def topLeft(self, x=None, y=None):
        if x == None:
            x = self.position
        if y == None:
            if self.topDown:
                x,y = divmod(x, self.down)
            else:
                y,x = divmod(x, self.across)

        return (
            self.margins[0]+x*self.labelsep[0],
            self.pagesize[1] - self.margins[1] - (y+1)*self.labelsep[1]
        )

    def advance(self):
        self.position += 1
        if self.position == self.across * self.down:
            self.canvas.showPage()
            self.position = 0

    def close(self):
        if self.position:
            self.canvas.showPage()
        self.canvas.save()
        self.canvas = None

    # To render, you can either create a template and tell me
    # "go draw N of these templates" or provide a callback.
    # Callback receives canvas, width, height.
    #
    # Or, pass a callable and an iterator.  We'll do one label
    # per iteration of the iterator.

    def render( self, thing, count, *args ):
        assert callable(thing) or isinstance(thing, str)
        if isinstance(count, Iterator):
            return self.render_iterator( thing, count )

        canv = self.canvas
        for i in range(count):
            canv.saveState()
            canv.translate( *self.topLeft() )
            if self.debug:
                canv.setLineWidth( 0.25 )
                canv.rect( 0, 0, self.size[0], self.size[1] )
            if callable(thing):
                thing( canv, self.size[0], self.size[1], *args )
            elif isinstance(thing, str):
                canv.doForm(thing)
            canv.restoreState()
            self.advance()

    def render_iterator( self, func, iterator ):
        canv = self.canvas
        for chunk in iterator:
            canv.saveState()
            canv.translate( *self.topLeft() )
            if self.debug:
                canv.setLineWidth( 0.25 )
                canv.rect( 0, 0, self.size[0], self.size[1] )
            func( canv, self.size[0], self.size[1], chunk )
            canv.restoreState()
            self.advance()