require 'prawn'
require 'prawn/table'
require 'bigdecimal'

class InvoicePdf
  FONTS_DIR = File.join($root, 'public', 'fonts')

  ISSUER = {
    name_latin:    'IE Sergei Poljanski',
    name_alt:      'SERGEI POLJANSKI',
    name_georgian: 'ინდ. მეწარმე სერგეი პოლჯანსკი',
    tax_id:        '304813343',
    reg_number:    'B26353511',
    registered:    '2026-05-04',
    address:       [
      'Ilia and Nino Nakashidze St, N 1, Building N3, Apt N3',
      'Krtsanisi, Tbilisi, Georgia'
    ],
    email:         'me@asxp.io',
    phone:         '+995 595 026 471',
    bank_name:     'Bank of Georgia',
    iban:          'GE53BG0000000612343299',
    swift:         'BAGAGE22'
  }.freeze

  COLOR_TEXT    = '111111'.freeze
  COLOR_MUTED   = '6F6F6F'.freeze
  COLOR_RULE    = 'DADADA'.freeze
  COLOR_ACCENT  = '1A1A1A'.freeze

  def self.render(invoice)
    new(invoice).render
  end

  def initialize(invoice)
    @invoice = invoice
  end

  def render
    pdf = Prawn::Document.new(
      page_size: 'A4',
      margin:    [40, 50, 50, 50],
      info:      {
        Title:    "Invoice #{@invoice.number}",
        Author:   ISSUER[:name_latin],
        Creator:  'asxp.io'
      }
    )
    register_fonts(pdf)
    pdf.font('NotoSans')
    pdf.fill_color COLOR_TEXT

    draw_header(pdf)
    draw_parties(pdf)
    draw_meta(pdf)
    draw_items(pdf)
    draw_totals(pdf)
    draw_payment(pdf)
    draw_footer(pdf)

    pdf.render
  end

  private

  def register_fonts(pdf)
    pdf.font_families.update(
      'NotoSans' => {
        normal: File.join(FONTS_DIR, 'NotoSans-Regular.ttf'),
        bold:   File.join(FONTS_DIR, 'NotoSans-Bold.ttf'),
        italic: File.join(FONTS_DIR, 'NotoSans-Italic.ttf')
      },
      'NotoSansGeorgian' => {
        normal: File.join(FONTS_DIR, 'NotoSansGeorgian-Regular.ttf'),
        bold:   File.join(FONTS_DIR, 'NotoSansGeorgian-Bold.ttf')
      }
    )
    pdf.fallback_fonts = ['NotoSansGeorgian']
  end

  def draw_header(pdf)
    pdf.font_size(20) { pdf.text 'INVOICE', style: :bold, character_spacing: 2 }
    pdf.move_down 2
    pdf.fill_color COLOR_MUTED
    pdf.font_size(9) { pdf.text @invoice.number }
    pdf.fill_color COLOR_TEXT
    pdf.move_down 16
    pdf.stroke_color COLOR_RULE
    pdf.stroke_horizontal_rule
    pdf.move_down 16
  end

  def draw_parties(pdf)
    top_y = pdf.y
    right = 285
    col_w = 250

    pdf.bounding_box([0, pdf.cursor], width: col_w) do
      draw_party_label(pdf, 'FROM')
      pdf.font_size(11) { pdf.text ISSUER[:name_latin], style: :bold, leading: 2 }
      pdf.font_size(9) do
        pdf.text ISSUER[:name_georgian], leading: 4
        pdf.move_down 8
        pdf.text ISSUER[:address].join("\n"), leading: 3
        pdf.move_down 8
        pdf.text "Tax ID: #{ISSUER[:tax_id]}",                            leading: 3
        pdf.text "Reg. №: #{ISSUER[:reg_number]} (#{ISSUER[:registered]})", leading: 3
        pdf.move_down 8
        pdf.text ISSUER[:email], leading: 3
        pdf.text ISSUER[:phone]
      end
    end
    from_y = pdf.y

    pdf.y = top_y
    pdf.bounding_box([right, pdf.cursor], width: pdf.bounds.right - right) do
      draw_party_label(pdf, 'BILL TO')
      pdf.font_size(11) { pdf.text @invoice.client_name, style: :bold, leading: 2 }
      pdf.font_size(9) do
        pdf.text @invoice.client_email, leading: 3
        unless @invoice.client_address.to_s.strip.empty?
          pdf.move_down 8
          pdf.text @invoice.client_address, leading: 3
        end
      end
    end
    bill_y = pdf.y

    pdf.y = [from_y, bill_y].min
    pdf.move_down 24
  end

  def draw_party_label(pdf, label)
    pdf.fill_color COLOR_MUTED
    pdf.font_size(8) { pdf.text label, character_spacing: 1.5 }
    pdf.fill_color COLOR_TEXT
    pdf.move_down 8
  end

  def draw_meta(pdf)
    pdf.stroke_color COLOR_RULE
    pdf.stroke_horizontal_rule
    pdf.move_down 10

    cells = [
      ['ISSUED',   @invoice.issued_on.strftime('%Y-%m-%d')],
      ['DUE',      @invoice.due_on.strftime('%Y-%m-%d')],
      ['CURRENCY', @invoice.currency],
      ['STATUS',   @invoice.status.upcase]
    ]
    col_w = pdf.bounds.width / cells.size.to_f
    top   = pdf.cursor

    cells.each_with_index do |(label, value), i|
      pdf.bounding_box([i * col_w, top], width: col_w) do
        pdf.fill_color COLOR_MUTED
        pdf.font_size(7) { pdf.text label, character_spacing: 1.2 }
        pdf.fill_color COLOR_TEXT
        pdf.move_down 3
        pdf.font_size(10) { pdf.text value, style: :bold }
      end
    end

    # Reserve the height the row actually used.
    pdf.move_down 30
    pdf.stroke_horizontal_rule
    pdf.move_down 16
  end

  def draw_items(pdf)
    header = ['Description', 'Qty', "Unit (#{@invoice.currency})", "Amount (#{@invoice.currency})"]
    rows = @invoice.items_array.map do |i|
      qty  = BigDecimal(i['qty'].to_s)
      unit = BigDecimal(i['unit_price'].to_s)
      [i['description'], fmt_qty(qty), fmt_money(unit), fmt_money(qty * unit)]
    end
    table_data = [header] + rows

    pdf.table(table_data, header: true, width: pdf.bounds.width,
              column_widths: { 0 => pdf.bounds.width - 270, 1 => 60, 2 => 100, 3 => 110 }) do
      cells.borders = [:bottom]
      cells.border_color = COLOR_RULE
      cells.padding = [8, 8, 8, 8]
      cells.size = 9
      row(0).font_style = :bold
      row(0).text_color = COLOR_MUTED
      row(0).size = 8
      row(0).background_color = 'FAFAFA'
      columns(1..3).align = :right
    end
    pdf.move_down 8
  end

  def draw_totals(pdf)
    total = @invoice.total
    rows = [
      ['Subtotal', "#{@invoice.currency} #{fmt_money(total)}"],
      ['Total',    "#{@invoice.currency} #{fmt_money(total)}"]
    ]
    if @invoice.currency != 'GEL'
      rows << ["In GEL (rate #{fmt_money(@invoice.gel_rate)})", "GEL #{fmt_money(@invoice.total_gel)}"]
    end

    pdf.bounding_box([pdf.bounds.right - 270, pdf.cursor], width: 270) do
      pdf.table(rows, cell_style: { borders: [], padding: [4, 0, 4, 0], size: 10 },
                column_widths: { 0 => 130, 1 => 140 }) do
        columns(0).text_color = COLOR_MUTED
        columns(1).align = :right
        row(1).font_style = :bold
        row(1).text_color = COLOR_ACCENT
        row(1).size = 12
      end
    end
    pdf.move_down 30
  end

  def draw_payment(pdf)
    pdf.fill_color COLOR_MUTED
    pdf.font_size(8) { pdf.text 'PAYMENT', character_spacing: 1.5 }
    pdf.fill_color COLOR_TEXT
    pdf.move_down 4
    pdf.font_size(9) do
      pdf.text "Bank: #{ISSUER[:bank_name]}"
      pdf.text "IBAN: #{ISSUER[:iban]}"
      pdf.text "SWIFT: #{ISSUER[:swift]}"
      pdf.text "Beneficiary: #{ISSUER[:name_latin]}"
    end
    unless @invoice.notes.to_s.strip.empty?
      pdf.move_down 14
      pdf.fill_color COLOR_MUTED
      pdf.font_size(8) { pdf.text 'NOTES', character_spacing: 1.5 }
      pdf.fill_color COLOR_TEXT
      pdf.move_down 4
      pdf.font_size(9) { pdf.text @invoice.notes }
    end
  end

  def draw_footer(pdf)
    pdf.repeat(:all) do
      pdf.canvas do
        pdf.fill_color COLOR_MUTED
        pdf.font_size(8) do
          pdf.draw_text(
            "#{ISSUER[:name_latin]} · Tax ID #{ISSUER[:tax_id]} · Small Business (1% turnover tax)",
            at: [50, 25]
          )
          pdf.draw_text("Page #{pdf.page_number}", at: [pdf.bounds.right - 50, 25])
        end
        pdf.fill_color COLOR_TEXT
      end
    end
  end

  def fmt_money(value)
    BigDecimal(value.to_s).round(2).to_s('F').then { |s| with_thousands(s) }
  end

  def fmt_qty(value)
    bd = BigDecimal(value.to_s)
    bd.frac.zero? ? bd.to_i.to_s : bd.to_s('F')
  end

  def with_thousands(numstr)
    int, frac = numstr.split('.')
    int = int.reverse.gsub(/(\d{3})(?=\d)/, '\\1,').reverse
    frac ? "#{int}.#{frac.ljust(2, '0')[0, 2]}" : "#{int}.00"
  end
end