From 60a1032f710d018c7c5bfc5d2880d5433c95bf61 Mon Sep 17 00:00:00 2001
From: Alex Ling <hkalexling@gmail.com>
Date: Thu, 20 Feb 2020 01:32:18 +0000
Subject: [PATCH] add a basic Mangadex API wrapper

---
 src/mangadex/api.cr | 211 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 211 insertions(+)
 create mode 100644 src/mangadex/api.cr

diff --git a/src/mangadex/api.cr b/src/mangadex/api.cr
new file mode 100644
index 0000000..ef273e0
--- /dev/null
+++ b/src/mangadex/api.cr
@@ -0,0 +1,211 @@
+require "http/client"
+require "json"
+require "csv"
+require "zip"
+
+macro string_properties (names)
+	{% for name in names %}
+		property {{name.id}} = ""
+	{% end %}
+end
+
+macro parse_strings_from_json (names)
+	{% for name in names %}
+		@{{name.id}} = obj[{{name}}].as_s
+	{% end %}
+end
+
+module Mangadex
+	class DownloadContext
+		property success = false
+		property url : String
+		property filename : String
+		property writer : Zip::Writer
+		property tries_remaning : Int32
+		def initialize(@url, @filename, @writer, @tries_remaning)
+		end
+	end
+	class Chapter
+		string_properties ["lang_code", "title", "volume", "chapter"]
+		property time = Time.local
+		property id : String
+		property language = ""
+		property pages = [] of {String, String} # filename, url
+		property groups = [] of {Int32, String} # group_id, group_name
+
+		def initialize(@id, json_obj : JSON::Any, lang : Hash(String, String))
+			self.parse_json json_obj, lang
+		end
+		def to_info_json
+			JSON.build do |json|
+				json.object do
+					{% for name in ["id", "title", "volume", "chapter",
+							"language"] %}
+						json.field {{name}}, @{{name.id}}
+					{% end %}
+					json.field "time", @time.to_unix.to_s
+					json.field "groups" do
+						json.object do
+							@groups.each do |gid, gname|
+								json.field gname, gid
+							end
+						end
+					end
+				end
+			end
+		end
+		def parse_json(obj, lang)
+			begin
+				parse_strings_from_json ["lang_code", "title", "volume",
+							 "chapter"]
+				language = lang[@lang_code]?
+				@language = language if language
+				@time = Time.unix obj["timestamp"].as_i
+				suffixes = ["", "_2", "_3"]
+				suffixes.each do |s|
+					gid = obj["group_id#{s}"].as_i
+					next if gid == 0
+					gname = obj["group_name#{s}"].as_s
+					@groups << {gid, gname}
+				end
+			rescue e
+				raise "failed to parse json: #{e}"
+			end
+		end
+		def download(dir, wait_seconds=5, retries=4)
+			name = "mangadex-chapter-#{@id}"
+			info_json_path = File.join dir, "#{name}.info.json"
+			zip_path = File.join dir, "#{name}.cbz"
+
+			puts "Writing info.josn to #{info_json_path}"
+			File.write info_json_path, self.to_info_json
+
+			writer = Zip::Writer.new zip_path
+
+			# Create a buffered channel. It works as an FIFO queue
+			channel = Channel(DownloadContext).new @pages.size
+
+			spawn do
+				@pages.each do |fn, url|
+					context = DownloadContext.new url, fn, writer, retries
+
+					puts "Downlaoding #{url}"
+					loop do
+						sleep wait_seconds.seconds
+						download_page context
+						break if context.success || context.tries_remaning <= 0
+						context.tries_remaning -= 1
+						puts "Retrying... Remaining retries: "\
+							"#{context.tries_remaning}"
+					end
+
+					channel.send context
+				end
+			end
+
+			spawn do
+				context_ary = [] of DownloadContext
+				@pages.size.times do
+					context = channel.receive
+					puts "[#{context.success}] #{context.url}"
+					context_ary << context
+				end
+				fail_count = context_ary.select{|ctx| !ctx.success}.size
+				puts "Download completed. "\
+					"#{fail_count}/#{context_ary.size} failed"
+				writer.close
+				puts "cbz File created at #{zip_path}"
+			end
+		end
+		def download_page(context)
+			headers = HTTP::Headers {
+				"User-agent" => "Mangadex.cr"
+			}
+			begin
+				HTTP::Client.get context.url, headers do |res|
+					return if !res.success?
+					context.writer.add context.filename, res.body_io
+				end
+				context.success = true
+			rescue e
+				puts e
+				context.success = false
+			end
+		end
+	end
+	class Manga
+		string_properties ["cover_url", "description", "title", "author",
+					"artist"]
+		property chapters = [] of Chapter
+		property id : String
+
+		def initialize(@id, json_obj : JSON::Any)
+			self.parse_json json_obj
+		end
+		def to_info_json
+			JSON.build do |json|
+				json.object do
+					{% for name in ["id", "title", "description",
+							"author", "artist", "cover_url"] %}
+						json.field {{name}}, @{{name.id}}
+					{% end %}
+				end
+			end
+		end
+		def parse_json(obj)
+			begin
+				parse_strings_from_json ["cover_url", "description", "title",
+							 "author", "artist"]
+			rescue e
+				raise "failed to parse json: #{e}"
+			end
+		end
+	end
+	class API
+		def initialize(@base_url = "https://mangadex.org/api/")
+			@lang = {} of String => String
+			CSV.each_row {{read_file "src/lang.csv"}} do |row|
+				@lang[row[1]] = row[0]
+			end
+		end
+		def get(url)
+			headers = HTTP::Headers {
+				"User-agent" => "Mangadex.cr"
+			}
+			res = HTTP::Client.get url, headers
+			raise "Failed to get #{url}. [#{res.status_code}] "\
+				"#{res.status_message}" if !res.success?
+			JSON.parse res.body
+		end
+		def get_manga(id)
+			obj = self.get File.join @base_url, "manga/#{id}"
+			begin
+				raise "" if obj["status"] != "OK"
+				manga = Manga.new id, obj["manga"]
+				obj["chapter"].as_h.map do |k, v|
+					chapter = Chapter.new k, v, @lang
+					manga.chapters << chapter
+				end
+				return manga
+			rescue
+				raise "Failed to parse JSON"
+			end
+		end
+		def get_chapter(chapter)
+			obj = self.get File.join @base_url, "chapter/#{chapter.id}"
+			begin
+				raise "" if obj["status"] != "OK"
+				server = obj["server"].as_s
+				hash = obj["hash"].as_s
+				chapter.pages = obj["page_array"].as_a.map{|fn|
+					{
+						fn.as_s,
+						"#{server}#{hash}/#{fn.as_s}"
+					}
+				}
+			rescue
+				raise "Failed to parse JSON"
+			end
+		end
+	end
+end