ticket-system/backend/core/pdf_generator.py

"""
Генерирует горизонтальный PDF-билет (600×250 pt).
Поддержка кириллицы: ищет системный TTF-шрифт; при неудаче — транслитерация.
"""
import io
import json
import os

import qrcode
from reportlab.lib.utils import ImageReader
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont
from reportlab.pdfgen import canvas

# ─── Cyrillic font detection ──────────────────────────────────────────────────

_FONT_CANDIDATES = [
    "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
    "/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf",
    "/usr/share/fonts/truetype/ubuntu/Ubuntu-R.ttf",
    "/usr/share/fonts/truetype/freefont/FreeSans.ttf",
    "/usr/share/fonts/truetype/liberation/LiberationSans-Regular.ttf",
]

_FONT_NAME = "Helvetica"  # fallback

for _path in _FONT_CANDIDATES:
    if os.path.exists(_path):
        try:
            pdfmetrics.registerFont(TTFont("CyrFont", _path))
            _FONT_NAME = "CyrFont"
        except Exception:
            pass
        break

# ─── Transliteration fallback (used when no Cyrillic font is found) ──────────

_TRANSLIT_MAP: dict[str, str] = {
    "а": "a",  "б": "b",  "в": "v",  "г": "g",  "д": "d",
    "е": "e",  "ё": "yo", "ж": "zh", "з": "z",  "и": "i",
    "й": "y",  "к": "k",  "л": "l",  "м": "m",  "н": "n",
    "о": "o",  "п": "p",  "р": "r",  "с": "s",  "т": "t",
    "у": "u",  "ф": "f",  "х": "kh", "ц": "ts", "ч": "ch",
    "ш": "sh", "щ": "shch","ъ": "",  "ы": "y",  "ь": "",
    "э": "e",  "ю": "yu", "я": "ya",
}


def _safe(text: str) -> str:
    """Pass text through unchanged if a Cyrillic font is registered; otherwise transliterate."""
    if _FONT_NAME != "Helvetica":
        return text
    result: list[str] = []
    for ch in text:
        lower = ch.lower()
        if lower in _TRANSLIT_MAP:
            t = _TRANSLIT_MAP[lower]
            result.append(t.capitalize() if ch.isupper() and t else t)
        else:
            result.append(ch)
    return "".join(result)


# ─── Color helpers ────────────────────────────────────────────────────────────

def _white(c: canvas.Canvas) -> None:
    c.setFillColorRGB(1.0, 1.0, 1.0)


def _muted(c: canvas.Canvas) -> None:
    c.setFillColorRGB(0.67, 0.67, 0.67)  # #aaaaaa


def _accent(c: canvas.Canvas) -> None:
    c.setFillColorRGB(0.89, 0.15, 0.21)  # #e32636


# ─── Main generator ───────────────────────────────────────────────────────────

def generate_qr_ticket(
    ticket_id: int,
    title: str,
    date_str: str,
    sector: str,
    row: int,
    number: int,
    price: int,
) -> bytes:
    """
    Renders a landscape ticket (600×250 pt) and returns PDF bytes.

    Left panel  — event info + seat details (x 30‥410)
    Right panel — QR code                  (x 420, y 50, 150×150)
    """
    W, H = 600, 250
    buffer = io.BytesIO()
    c = canvas.Canvas(buffer, pagesize=(W, H))

    # ── Background ──
    c.setFillColorRGB(0.1, 0.1, 0.1)
    c.rect(0, 0, W, H, fill=1, stroke=0)

    # ── Accent top bar ──
    c.setFillColorRGB(0.89, 0.15, 0.21)
    c.rect(0, H - 6, W, 6, fill=1, stroke=0)

    # ── Ticket ID badge (top-right of left panel) ──
    _muted(c)
    c.setFont(_FONT_NAME, 9)
    c.drawRightString(400, H - 20, f"#{ticket_id}")

    # ── Tournament title ──
    _white(c)
    c.setFont(_FONT_NAME, 20)
    c.drawString(30, H - 50, _safe(title))

    # ── Date & venue ──
    _white(c)
    c.setFont(_FONT_NAME, 12)
    c.drawString(30, H - 72, _safe(date_str))

    _muted(c)
    c.setFont(_FONT_NAME, 12)
    c.drawString(30, H - 90, _safe("Место: Main Arena, Москва"))

    # ── Separator ──
    c.setStrokeColorRGB(0.25, 0.25, 0.25)
    c.setLineWidth(0.8)
    c.line(30, H - 105, 400, H - 105)

    # ── Seat details grid ──
    labels = [
        (_safe("Сектор"), str(sector)),
        (_safe("Ряд"),    str(row)),
        (_safe("Место"),  str(number)),
        (_safe("Цена"),   f"{price:,} RUB".replace(",", " ")),
    ]

    col_w = 90
    x_start = 30
    y_label = H - 130
    y_value = H - 148

    for i, (label, value) in enumerate(labels):
        x = x_start + i * col_w

        _muted(c)
        c.setFont(_FONT_NAME, 9)
        c.drawString(x, y_label, label)

        _white(c)
        c.setFont(_FONT_NAME, 14)
        c.drawString(x, y_value, value)

    # ── Perforated divider line (left panel / QR panel) ──
    c.setStrokeColorRGB(0.25, 0.25, 0.25)
    c.setDash(4, 4)
    c.setLineWidth(0.8)
    c.line(415, 15, 415, H - 15)
    c.setDash()  # reset dash

    # ── Scan hint ──
    _muted(c)
    c.setFont(_FONT_NAME, 8)
    c.drawCentredString(495, 30, _safe("Сканировать при входе"))

    # ── QR code ──
    qr_data = json.dumps(
        {"id": ticket_id, "t": title, "s": sector, "r": row, "m": number},
        ensure_ascii=False,
        separators=(",", ":"),
    )
    qr = qrcode.QRCode(box_size=5, border=1, error_correction=qrcode.constants.ERROR_CORRECT_M)
    qr.add_data(qr_data)
    qr.make(fit=True)
    img = qr.make_image(fill_color="white", back_color="#1a1a1a")

    img_buf = io.BytesIO()
    img.save(img_buf, format="PNG")
    img_buf.seek(0)

    c.drawImage(ImageReader(img_buf), 420, 50, width=150, height=150)

    c.showPage()
    c.save()
    buffer.seek(0)
    return buffer.read()