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muse-dl/src/fetch.cr

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5.4 KiB

require "crest"
require "./errors/*"
require "myhtml"
module Muse::Dl
class Fetch
USER_AGENT = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36"
DOWNLOAD_TIMEOUT_SECS = 60
HEADERS = {
"User-Agent" => USER_AGENT,
"Accept" => "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
"Accept-Language" => "en-US,en;q=0.5",
"Connection" => "keep-alive",
}
def self.article_file_name(id : String, tmp_path : String)
"#{tmp_path}/article-#{id}.pdf"
end
def self.chapter_file_name(id : String, tmp_path : String)
"#{tmp_path}/chapter-#{id}.pdf"
end
def self.cleanup(tmp_path : String, id : String)
fns = chapter_file_name(id, tmp_path)
File.delete(fns) if File.exists?(fns)
end
def self.cleanup_articles(tmp_path : String, id : String)
fns = article_file_name(id, tmp_path)
File.delete(fns) if File.exists?(fns)
end
def self.save_url(url : String, referer : String, file_name : String, tmp_path : String, cookie : String | Nil = nil, bookmark_title : String | Nil = nil, strip_first_page = true)
tmp_pdf_file = "#{file_name}.tmp"
if File.exists? file_name
puts "#{file_name} already downloaded"
return
end
uri = URI.parse(url)
http_client = HTTP::Client.new(uri)
# Raise a IO::TimeoutError after 60 seconds.
http_client.read_timeout = DOWNLOAD_TIMEOUT_SECS
headers = HEADERS.merge({
"Referer" => referer,
})
if cookie
headers["Cookie"] = cookie
end
request = Crest::Request.new(:get, url, headers: headers, max_redirects: 0, handle_errors: false)
begin
response = request.execute
rescue ex : IO::TimeoutError
raise Muse::Dl::Errors::DownloadError.new("Error downloading #{url}. Download took longer than #{DOWNLOAD_TIMEOUT_SECS} seconds.")
end
# TODO: Add validation for the downloaded file (should be PDF)
if !response.success?
raise Muse::Dl::Errors::DownloadError.new("Error downloading chapter. HTTP response code: #{response.status}")
end
content_type = response.headers["Content-Type"]
if content_type.is_a? String
if /html/.match content_type
response.body.each_line do |line|
# https://muse.jhu.edu/chapter/2383438/pdf
# https://muse.jhu.edu/book/67393
# Errors are Unable to determine page runs / Unable to construct chapter PDF
if /Unable to/.match line
raise Muse::Dl::Errors::MuseCorruptPDF.new("Error: MUSE is unable to generate PDF for #{url}")
end
if /Your IP has requested/.match line
raise Muse::Dl::Errors::DownloadError.new("Error: MUSE Rate-limit reached")
end
end
end
end
File.open(tmp_pdf_file, "w") do |file|
file << response.body
if file.size == 0
raise Muse::Dl::Errors::DownloadError.new("Error: downloaded chapter file size is zero. Response Content-Length header was #{headers["Content-Length"]}")
end
end
pdftk = Muse::Dl::Pdftk.new tmp_path
pdftk.strip_first_page tmp_pdf_file if strip_first_page
if bookmark_title
# Run pdftk and add the bookmark to the file
pdftk.add_bookmark tmp_pdf_file, bookmark_title
end
# Now we can move the file to the proper PDF filename
File.rename tmp_pdf_file, file_name
end
def self.save_chapter(tmp_path : String, chapter_id : String, chapter_title : String, cookie : String | Nil = nil, add_bookmark = true, strip_first_page = true)
final_pdf_file = chapter_file_name chapter_id, tmp_path
if File.exists? final_pdf_file
puts "#{chapter_id} already downloaded"
return
end
# TODO: Remove this hardcoding, and make this more generic by generating it within the Book class
url = "https://muse.jhu.edu/chapter/#{chapter_id}/pdf"
referer = "https://muse.jhu.edu/verify?url=%2Fchapter%2F#{chapter_id}%2Fpdf"
save_url(url, referer, final_pdf_file, tmp_path, cookie, chapter_title, strip_first_page)
puts "Downloaded #{chapter_id}"
end
def self.save_article(tmp_path : String, article_id : String, cookie : String | Nil = nil, article_title = nil, strip_first_page = true)
file_name = article_file_name article_id, tmp_path
url = "https://muse.jhu.edu/article/#{article_id}/pdf"
referer = "https://muse.jhu.edu/article/#{article_id}"
save_url(url, referer, file_name, tmp_path, cookie, article_title, strip_first_page)
end
def self.get_info(url : String)
match = /https:\/\/muse.jhu.edu\/(book|journal|issue|article)\/(\d+)/.match url
if match
begin
response = Crest.get(url).to_s
case match[1]
when "book"
return Muse::Dl::Book.new response
when "journal"
return Muse::Dl::Journal.new response
when "issue"
return Muse::Dl::Issue.new match[2], response
when "article"
return Muse::Dl::Article.new match[2]
end
rescue ex : Crest::NotFound
raise Muse::Dl::Errors::InvalidLink.new("Error - could not download url: #{url}")
end
else
raise Muse::Dl::Errors::InvalidLink.new("Error - url does not match expected pattern: #{url}")
end
end
end
end