import os
from io import BytesIO
from reportlab.graphics.barcode import code128
from reportlab.lib.pagesizes import mm
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont
from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer, PageBreak

from constants import APP_PATH


class PDFGenerator:
    def __init__(self):
        ASSETS_FOLDER = os.path.join(APP_PATH, 'assets')
        FONTS_FOLDER = os.path.join(ASSETS_FOLDER, 'fonts')
        FONT_FILE_PATH = os.path.join(FONTS_FOLDER, 'DejaVuSans.ttf')
        self.page_width = 58 * mm
        self.page_height = 40 * mm

        pdfmetrics.registerFont(TTFont('DejaVuSans', FONT_FILE_PATH))

        # Get standard styles and create a new style with a smaller font size
        styles = getSampleStyleSheet()
        self.small_style = ParagraphStyle(
            'Small',
            parent=styles['Normal'],
            fontName='DejaVuSans',  # Specify the new font
            fontSize=6,
            leading=7,
            spaceAfter=2,
            leftIndent=2,
            rightIndent=2
        )

    def generate_small_text(self, barcode_value, text, num_duplicates=1):
        buffer = BytesIO()

        # Create document with specified page size
        doc = SimpleDocTemplate(buffer,
                                pagesize=(self.page_width, self.page_height),
                                rightMargin=1 * mm,
                                leftMargin=1 * mm,
                                topMargin=1 * mm,
                                bottomMargin=1 * mm)

        # Create paragraph with new style
        paragraph = Paragraph(text, self.small_style)

        # Get the width and height of the paragraph
        paragraph_width, paragraph_height = paragraph.wrap(self.page_width - 2 * mm, self.page_height)
        # Create barcode
        barcode_height = (self.page_height - paragraph_height * mm)
        available_width = self.page_width - 2 * mm  # Adjust for margins

        # Approximate number of elements in a Code 128 barcode for average length
        num_elements = 11 * len(barcode_value)  # Rough estimate: 11 elements per character

        # Calculate barWidth
        bar_width = available_width / num_elements
        barcode = code128.Code128(barcode_value,
                                  barWidth=bar_width,
                                  barHeight=barcode_height,
                                  humanReadable=True)

        # Function to draw barcode on canvas
        def add_barcode(canvas, doc):
            barcode_width = barcode.width
            barcode_x = (self.page_width - barcode_width) / 2  # Center the barcode
            barcode.drawOn(canvas, barcode_x, self.page_height - barcode.height - 5)

        # Create list of elements to add to the document
        elements = []
        for _ in range(num_duplicates):
            elements.append(Spacer(1, barcode_height + 2 * mm))
            elements.append(paragraph)
            elements.append(PageBreak())

        # Build document
        doc.build(elements[:-1], onFirstPage=add_barcode, onLaterPages=add_barcode)  # Remove the last PageBreak

        buffer.seek(0)
        return buffer

    def generate_large_text(self, barcode_value, text, num_duplicates=1):
        buffer = BytesIO()

        # Create document with specified page size
        doc = SimpleDocTemplate(buffer,
                                pagesize=(self.page_width, self.page_height),
                                rightMargin=1 * mm,
                                leftMargin=1 * mm,
                                topMargin=1 * mm,
                                bottomMargin=1 * mm)

        # Create paragraph with new style
        paragraph = Paragraph(text, self.small_style)

        # Create barcode
        barcode = code128.Code128(barcode_value, humanReadable=True)

        # Function to draw barcode on canvas
        def add_barcode(canvas, doc):
            barcode_width = barcode.width
            barcode_x = (self.page_width - barcode_width) / 2  # Center the barcode
            barcode.drawOn(canvas, barcode_x, self.page_height - barcode.height - 5)

        # Create list of elements to add to the document
        elements = []
        for _ in range(num_duplicates):
            elements.append(Spacer(1, 8 * mm))
            elements.append(paragraph)
            elements.append(PageBreak())

        # Build document
        doc.build(elements[:-1], onFirstPage=add_barcode, onLaterPages=add_barcode)  # Remove the last PageBreak

        buffer.seek(0)
        return buffer

    def generate(self, barcode_value, text, num_duplicates=1):
        paragraph = Paragraph(text, self.small_style)
        # Get the width and height of the paragraph
        paragraph_width, paragraph_height = paragraph.wrap(self.page_width - 2 * mm, self.page_height)
        if paragraph_height > 30:
            return self.generate_large_text(barcode_value, text, num_duplicates)
        return self.generate_small_text(barcode_value, text, num_duplicates)