61        var
62        bbLen = 3,
63            enCharLen = 4,
64            inpLen = inputStr.length,
65            inx = 0,
66            jnx,
67            keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" + "0123456789+/=",
68            output = "",
69            paddingBytes = 0;
70        var
71        bytebuffer = new Array(bbLen),
72            encodedCharIndexes = new Array(enCharLen);
73
74        while (inx < inpLen) {
75            for (jnx = 0; jnx < bbLen; ++jnx) {
76                /*--- Throw away high-order byte, as documented at:
77              https://.mozilla.org/En/Using_XMLHttpRequest#Handling_binary_data
78            */
79                if (inx < inpLen) bytebuffer[jnx] = inputStr.charCodeAt(inx++) & 0xff;
80                else bytebuffer[jnx] = 0;
81            }
82
83            /*--- Get each encoded character, 6 bits at a time.
84            index 0: first  6 bits
85            index 1: second 6 bits
86                        (2 least significant bits from inputStr byte 1
87                         + 4 most significant bits from byte 2)
88            index 2: third  6 bits
89                        (4 least significant bits from inputStr byte 2
90                         + 2 most significant bits from byte 3)
91            index 3: forth  6 bits (6 least significant bits from inputStr byte 3)
92        */
93            encodedCharIndexes[0] = bytebuffer[0] >> 2;
94            encodedCharIndexes[1] = ((bytebuffer[0] & 0x3) << 4) | (bytebuffer[1] >> 4);
95            encodedCharIndexes[2] = ((bytebuffer[1] & 0x0f) << 2) | (bytebuffer[2] >> 6);
96            encodedCharIndexes[3] = bytebuffer[2] & 0x3f;
97
98            //--- Determine whether padding happened, and adjust accordingly.
99            paddingBytes = inx - (inpLen - 1);
100            switch (paddingBytes) {
101                case 1:
102                    // Set last character to padding char
103                    encodedCharIndexes[3] = 64;
104                    break;
105                case 2:
106                    // Set last 2 characters to padding char
107                    encodedCharIndexes[3] = 64;
108                    encodedCharIndexes[2] = 64;
109                    break;
110                default:
111                    break; // No padding - proceed
112            }
113
114            /*--- Now grab each appropriate character out of our keystring,
115            based on our index array and append it to the output string.
116        */
117            for (jnx = 0; jnx < enCharLen; ++jnx)
118                output += keyStr.charAt(encodedCharIndexes[jnx]);
119        }
120        return output;
121    }
122
123    function updatePagesDoneCounter() {
124        if (pagesDone % 5 === 0) {
125            document.getElementById("dhdl_status").textContent = "Downloading " + pagesDone + " of " + pagesTotal + " pages...";
126        }
127    }
128
129    // add download buttons to the bookshelf
130    if (window.location.pathname == "/bookshelf") {
131        // TODO: check if "stack by series" is enabled, and if so, don't add the download buttons
132        var books = document.getElementsByClassName("bookshelf-item");
133        for (var i = 0; i < books.length; i++) {
134            var book = books[i];
135            var btn = document.createElement("a");
136            btn.setAttribute("href", "/read/" + book.id + "#download");
137            btn.setAttribute("class", "button blue collection-read");
138            btn.setAttribute("style", "margin-top: 6px;");
139            btn.textContent = "Download";
140            book.appendChild(btn);
141        }
142
143    } else if (window.location.pathname.startsWith("/read/")) {
144
145        if (window.location.hash == "#download") {
146
147            // create box for showing status of download
148            var box = document.createElement("div");
149            box.id = "dhdl_box";
150            box.setAttribute("style", "background-color:#ffaaaa; border:2px solid #111; border-radius:5px; opacity:0.9; text-align:center; font-size:22px; width:400px; height:150px; margin:auto; position:absolute; top:0; left:0; bottom:0; right:0; z-index:10000;");
151
152            var boxTitle = document.createElement("h1");
153            boxTitle.textContent = "Dark Horse Downloader";
154            box.appendChild(boxTitle);
155
156            var boxStatus = document.createElement("p");
157            boxStatus.id = "dhdl_status";
158            boxStatus.textContent = "Starting up...";
159            box.appendChild(boxStatus);
160
161            document.body.appendChild(box);
162
163
164            var bookTitle = document.getElementById("bookreader-title").getElementsByTagName("h2")[0].textContent;
165            var bookTitleSafe = bookTitle.replace(/\s+/gi, ' ').replace(/[^a-z0-9 ]/gi, '_');
166
167            var pageUrls = [];
168            for (var i = 0; i < book_manifest.pages.length; i++) {
169                var page = book_manifest.pages[i];
170                var url = window.location.protocol + "//" + window.location.host + book_manifest.base_url + page.src_image;
171                pageUrls.push(url);
172            }
173            pagesTotal = book_manifest.pages.length;
174            updatePagesDoneCounter();
175
176            // reverse order for right-to-left books (i.e. manga)
177            if (book_manifest.is_rtl) {
178                pageUrls.reverse();
179            }
180
181            var zip = new JSZip();
182
183            Promise.all(pageUrls.map(function(url, index) {
184                return new Promise(function(resolve) {
185                    GM_xmlhttpRequest({
186                        method: "GET",
187                        url: url,
188                        onload: function(response) {
189                            zip.file(padToFive(index) + ".jpg", customBase64Encode(response.responseText), {
190                                base64: true
191                            });
192                            pagesDone++;
193                            updatePagesDoneCounter();
194                            resolve();
195                        },
196                        overrideMimeType: 'text/plain; charset=x-user-defined'
197                    });
198                });
199            })).then(function() {
200                document.getElementById("dhdl_status").textContent = "Creating zip file...";
201                zip.generateAsync({
202                    type: "blob"
203                }).then(function(content) {
204                    document.getElementById("dhdl_status").textContent = "Done!";
205                    downloadURI(URL.createObjectURL(content), bookTitleSafe + ".cbz");
206                    setTimeout(function() {
207                        document.body.removeChild(box);
208                    }, 3000);
209                });
210            });
211        }
212    }
213})();