Initial project upload

backend/app/services/qr.py

@@ -0,0 +1,70 @@
+"""QR generation engine. No credit deduction — generation is free and unlimited."""
+import io
+import secrets
+import zipfile
+
+import segno
+
+from app.core.config import settings
+from app.models.documents import QRStyle
+
+_EC_MAP = {"L": "l", "M": "m", "Q": "q", "H": "h"}
+
+
+def new_code(prefix: str = "vp") -> str:
+    return f"{prefix}{secrets.token_urlsafe(8).replace('-', '').replace('_', '')[:10]}".lower()
+
+
+def verify_url(code: str) -> str:
+    return f"{settings.frontend_url}/v/{code}"
+
+
+def _make(code: str, style: QRStyle) -> segno.QRCode:
+    ec = _EC_MAP.get(style.error_correction.upper(), "m")
+    if style.logo_url:
+        ec = "h"  # force high error correction when a logo is overlaid
+    return segno.make(verify_url(code), error=ec)
+
+
+def render_png(code: str, style: QRStyle, scale: int = 10) -> bytes:
+    buf = io.BytesIO()
+    _make(code, style).save(buf, kind="png", scale=scale,
+                            dark=style.fg_color, light=style.bg_color,
+                            border=style.quiet_zone)
+    return buf.getvalue()
+
+
+def render_svg(code: str, style: QRStyle, scale: int = 10) -> bytes:
+    buf = io.BytesIO()
+    _make(code, style).save(buf, kind="svg", scale=scale,
+                            dark=style.fg_color, light=style.bg_color,
+                            border=style.quiet_zone)
+    return buf.getvalue()
+
+
+def render_pdf(code: str, style: QRStyle, scale: int = 10) -> bytes:
+    buf = io.BytesIO()
+    _make(code, style).save(buf, kind="pdf", scale=scale,
+                            dark=style.fg_color, light=style.bg_color,
+                            border=style.quiet_zone)
+    return buf.getvalue()
+
+
+def render(code: str, style: QRStyle, fmt: str = "png") -> tuple[bytes, str]:
+    fmt = fmt.lower()
+    if fmt == "svg":
+        return render_svg(code, style), "image/svg+xml"
+    if fmt == "pdf":
+        return render_pdf(code, style), "application/pdf"
+    return render_png(code, style), "image/png"
+
+
+def zip_codes(codes: list[str], style: QRStyle, fmt: str = "png") -> bytes:
+    """Bundle per-pack QRs (Option 2) into a single downloadable ZIP."""
+    buf = io.BytesIO()
+    ext = {"svg": "svg", "pdf": "pdf"}.get(fmt.lower(), "png")
+    with zipfile.ZipFile(buf, "w", zipfile.ZIP_DEFLATED) as zf:
+        for i, code in enumerate(codes, start=1):
+            data, _ = render(code, style, fmt)
+            zf.writestr(f"qr_{i:05d}_{code}.{ext}", data)
+    return buf.getvalue()