csv_dthreejs.py

# -*- coding: utf-8 -*-
#
# This file is part of Invenio.
# Copyright (C) 2015-2019 CERN.
#
# Invenio is free software; you can redistribute it and/or modify it
# under the terms of the MIT License; see LICENSE file for more details.

"""Render a CSV file using d3.js."""

import csv

from flask import current_app, render_template

from ..proxies import current_previewer
from ..utils import detect_encoding

previewable_extensions = ["csv", "dsv"]


def validate_csv(file):
    """Return dialect information about given csv file."""
    max_file_size = current_app.config.get(
        "PREVIEWER_MAX_FILE_SIZE_BYTES", 10 * 1024 * 1024
    )
    if file.size > max_file_size:
        return False

    try:
        # Detect encoding and dialect
        with file.open() as fp:
            encoding = detect_encoding(fp, default="utf-8")
            sample = fp.read(
                current_app.config.get("PREVIEWER_CSV_VALIDATION_BYTES", 1024)
            )
            allowed_delimiters = current_app.config.get(
                "PREVIEWER_CSV_SNIFFER_ALLOWED_DELIMITERS", None
            )
            delimiter = (
                csv.Sniffer()
                .sniff(sample=sample.decode(encoding), delimiters=allowed_delimiters)
                .delimiter
            )
            is_valid = True
    except Exception as e:
        current_app.logger.debug("File {0} is not valid CSV: {1}".format(file.uri, e))
        encoding = ""
        delimiter = ""
        is_valid = False

    return {"delimiter": delimiter, "encoding": encoding, "is_valid": is_valid}


def can_preview(file):
    """Determine if the given file can be previewed."""
    if file.is_local() and file.has_extensions(".csv", ".dsv"):
        return validate_csv(file)["is_valid"]
    return False


def preview(file):
    """Render the appropriate template with embed flag."""
    file_info = validate_csv(file)
    return render_template(
        "invenio_previewer/csv_bar.html",
        file=file,
        delimiter=file_info["delimiter"],
        encoding=file_info["encoding"],
        js_bundles=current_previewer.js_bundles + ["d3_csv.js"],
        css_bundles=current_previewer.css_bundles,
    )