defmodule PdfGenerator do
@vsn "0.2.0"
@moduledoc """
# PdfGenerator
Provides a simple wrapper around [wkhtmltopdf](http://wkhtmltopdf.org) and
[pdftk](https://www.pdflabs.com/tools/pdftk-the-pdf-toolkit/) to generate
possibly encrypted PDFs from an HTML source.
# System requirements
- wkhtmltopdf
- pdftk (optional, for encrypted PDFs)
- goon (optional, for Porcelain shalle wrapper)
Precompiled **wkhtmltopdf** binaries can be obtained here:
http://wkhtmltopdf.org/downloads.html
**pdftk** should be available as package on your system via
- `apt-get install pdftk` on Debian/Ubuntu
- `brew pdftk` on OSX (you'll need homebrew, of course)
- Install the Exe-Installer on Windows found the project's homepage (link
above)
**goon** is available here:
https://github.com/alco/goon/releases
"""
use Application
alias Porcelain.Result
# See http://elixir-lang.org/docs/stable/elixir/Application.html
# for more information on OTP Applications
def start(_type, _args) do
import Supervisor.Spec, warn: false
children = [
# Define workers and child supervisors to be supervised
# worker(TestApp.Worker, [arg1, arg2, arg3])
]
opts = [strategy: :one_for_one, name: PdfGenerator.Supervisor]
Supervisor.start_link(children, opts)
end
# return file name of generated pdf
# requires: Porcelain, Random
@doc """
Generates a pdf file from given html string. Returns a string containing a
temporary file path for that PDF.
options:
- page_size: output page size, defaults to "A4"
- open_password: password required to open PDF. Will apply encryption to PDF
- edit_password: password required to edit PDF
- shell_params: list of command-line arguments to wkhtmltopdf
see http://wkhtmltopdf.org/usage/wkhtmltopdf.txt for all options
# Examples
pdf_path_1 = PdfGenerator.generate "Boom
"
pdf_path_2 = PdfGenerator.generate(
"Boom
",
page_size: "A5",
open_password: "secret",
edit_password: "g3h31m",
shell_params: [ "--outline", "--outline-depth3", "3" ]
)
"""
def generate( html ) do
generate html, page_size: "A4"
end
def generate( html, options ) do
wkhtml_path = System.find_executable("wkhtmltopdf")
if wkhtml_path == nil, do: raise "Cannot find wkhtmltopdf in path. See http://wkhtmltopdf.org"
html_file = Path.join System.tmp_dir, Random.string <> ".html"
File.write html_file, html
pdf_file = Path.join System.tmp_dir, Random.string <> ".pdf"
shell_params = [
"--page-size", Keyword.get( options, :page_size ) || "A4",
Keyword.get( options, :shell_params ) || [] # will be flattened
]
%Result{ out: _output, status: status } = Porcelain.exec(
wkhtml_path, List.flatten( [ shell_params, html_file, pdf_file ] )
)
case status do
0 ->
case Keyword.get options, :open_password do
nil -> { :ok, pdf_file }
user_pw -> encrypt_pdf(
pdf_file,
user_pw,
Keyword.get( options, :edit_password )
)
end
_ -> { :error, "wkhtmltopdf returned with nonzero vaule. This is likely du to bad shell_params" }
end
end
def encrypt_pdf( pdf_input_path, user_pw, owner_pw ) do
pdftk_path = System.find_executable "pdftk"
if pdftk_path == nil, do: raise "Cannot find pdftk in path. See https://www.pdflabs.com/tools/pdftk-the-pdf-toolkit/"
if owner_pw == nil, do: owner_pw = Random.string(16)
if user_pw == nil, do: user_pw = Random.string(16)
pdf_output_file = Path.join System.tmp_dir, Random.string <> ".pdf"
%Result{ out: _output, status: status } = Porcelain.exec(
pdftk_path, [
pdf_input_path,
"output", pdf_output_file,
"owner_pw", owner_pw,
"user_pw", user_pw,
"encrypt_128bit",
"allow", "Printing", "CopyContents"
]
)
case status do
0 -> { :ok, pdf_output_file }
_ -> { :error, "Encrpying the PDF via pdftk failed" }
end
end
end