class PdfContainer {
    fileName;
    pagesContainer;
    pagesContainerWrapper;
    pdfAdapters;
    downloadLink;

    constructor(id, wrapperId, pdfAdapters) {
        this.pagesContainer = document.getElementById(id)
        this.pagesContainerWrapper = document.getElementById(wrapperId);
        this.downloadLink = null;
        this.movePageTo = this.movePageTo.bind(this);
        this.addPdfs = this.addPdfs.bind(this);
        this.addPdfsFromFiles = this.addPdfsFromFiles.bind(this);
        this.rotateElement = this.rotateElement.bind(this);
        this.rotateAll = this.rotateAll.bind(this);
        this.exportPdf = this.exportPdf.bind(this);
        this.updateFilename = this.updateFilename.bind(this);
        this.setDownloadAttribute = this.setDownloadAttribute.bind(this);
        this.preventIllegalChars = this.preventIllegalChars.bind(this);

        this.pdfAdapters = pdfAdapters;

        this.pdfAdapters.forEach(adapter => {
            adapter.setActions({
                movePageTo: this.movePageTo,
                addPdfs: this.addPdfs,
                rotateElement: this.rotateElement,
            })
        })

        window.addPdfs = this.addPdfs;
        window.exportPdf = this.exportPdf;
        window.rotateAll = this.rotateAll;

        const filenameInput = document.getElementById('filename-input');
        const downloadBtn = document.getElementById('export-button');

        filenameInput.onkeyup = this.updateFilename;
        filenameInput.onkeydown = this.preventIllegalChars;
        filenameInput.disabled = true;
        filenameInput.innerText = "";
        downloadBtn.disabled = true;
    }

    movePageTo(startElement, endElement, scrollTo = false) {
        const childArray = Array.from(this.pagesContainer.childNodes);
        const startIndex = childArray.indexOf(startElement);
        const endIndex = childArray.indexOf(endElement);
        this.pagesContainer.removeChild(startElement);
        if(!endElement) {
            this.pagesContainer.append(startElement);
        } else {
            this.pagesContainer.insertBefore(startElement, endElement);
        }

        if(scrollTo) {
            const { width } = startElement.getBoundingClientRect();
            const vector = (endIndex !== -1 && startIndex > endIndex)
                ?  0-width
                : width;
            
            this.pagesContainerWrapper.scroll({
                left: this.pagesContainerWrapper.scrollLeft + vector,
            })
        }
    }

    addPdfs(nextSiblingElement) {
        var input = document.createElement('input');
        input.type = 'file';
        input.multiple = true;
        input.setAttribute("accept", "application/pdf");
        input.onchange = async(e) => {
            const files = e.target.files;
            if (files.length > 0) {
                const filenameInput = document.getElementById('filename-input');
                const pagesContainer = document.getElementById('pages-container');
                const downloadBtn = document.getElementById('export-button');

                filenameInput.disabled = false;

                if (pagesContainer.childElementCount === 0) {
                    filenameInput.value = "";
                    this.filename = null;
                    downloadBtn.disabled = true;
                } else {
                    this.filename = filenameInput.value;
                }

                if (this.filename === null || this.filename === undefined) {
                    filenameInput.value = files[0].name;
                } else {
                    filenameInput.value = this.filename;
                }

            }

            this.addPdfsFromFiles(files, nextSiblingElement);
        }

        input.click();
    }

    async addPdfsFromFiles(files, nextSiblingElement) {
        this.fileName = files[0].name;
        for (var i=0; i < files.length; i++) {
            await this.addPdfFile(files[i], nextSiblingElement);
        }

        document.querySelectorAll(".enable-on-file").forEach(element => {
            element.disabled = false;
        });
    }

    rotateElement(element, deg) {
        var lastTransform = element.style.rotate;
        if (!lastTransform) {
            lastTransform = "0";
        }
        const lastAngle = parseInt(lastTransform.replace(/[^\d-]/g, ''));
        const newAngle = lastAngle + deg;

        element.style.rotate = newAngle + "deg";
    }

    async addPdfFile(file, nextSiblingElement) {
        const { renderer, pdfDocument } = await this.loadFile(file);

        for (var i=0; i < renderer.pageCount; i++) {
            const div = document.createElement('div');

            div.classList.add("page-container");

            var img = document.createElement('img');
            img.classList.add('page-image')
            const imageSrc = await renderer.renderPage(i)
            img.src = imageSrc;
            img.pageIdx = i;
            img.rend = renderer;
            img.doc = pdfDocument;
            div.appendChild(img);

            this.pdfAdapters.forEach((adapter) => {
                adapter.adapt?.(div)
            })
            if (nextSiblingElement) {
                this.pagesContainer.insertBefore(div, nextSiblingElement);
            } else {
                this.pagesContainer.appendChild(div);
            }
        }
    }

    async loadFile(file) {
        var objectUrl = URL.createObjectURL(file);
        var pdfDocument = await this.toPdfLib(objectUrl);
        var renderer = await this.toRenderer(objectUrl);
        return { renderer, pdfDocument };
    }

    async toRenderer(objectUrl) {
		pdfjsLib.GlobalWorkerOptions.workerSrc = 'pdfjs/pdf.worker.js'
        const pdf = await pdfjsLib.getDocument(objectUrl).promise;
        return {
            document: pdf,
            pageCount: pdf.numPages,
            renderPage: async function(pageIdx) {
                const page = await this.document.getPage(pageIdx+1);

                const canvas = document.createElement("canvas");

                // set the canvas size to the size of the page
                if (page.rotate == 90 || page.rotate == 270) {
                    canvas.width = page.view[3];
                    canvas.height = page.view[2];
                } else {
                    canvas.width = page.view[2];
                    canvas.height = page.view[3];
                }

                // render the page onto the canvas
                var renderContext = {
                    canvasContext: canvas.getContext("2d"),
                    viewport: page.getViewport({ scale: 1 })
                };

                await page.render(renderContext).promise;
                return canvas.toDataURL();
            }
        };
    }

    async toPdfLib(objectUrl) {
        const existingPdfBytes = await fetch(objectUrl).then(res => res.arrayBuffer());
        const pdfDoc = await PDFLib.PDFDocument.load(existingPdfBytes, { ignoreEncryption: true });
        return pdfDoc;
    }

    

    rotateAll(deg) {
        for (var i=0; i<this.pagesContainer.childNodes.length; i++) {
            const img = this.pagesContainer.childNodes[i].querySelector("img");
            if (!img) continue;
            this.rotateElement(img, deg)
        }
    }

    async exportPdf() {
        const pdfDoc = await PDFLib.PDFDocument.create();
        for (var i=0; i<this.pagesContainer.childNodes.length; i++) {
            const img = this.pagesContainer.childNodes[i].querySelector("img");
            if (!img) continue;
            const pages = await pdfDoc.copyPages(img.doc, [img.pageIdx])
            const page = pages[0];

            const rotation = img.style.rotate;
            if (rotation) {
                const rotationAngle = parseInt(rotation.replace(/[^\d-]/g, ''));
                page.setRotation(PDFLib.degrees(page.getRotation().angle + rotationAngle))
            }
            
            pdfDoc.addPage(page);
        }
        const pdfBytes = await pdfDoc.save();
        const pdfBlob = new Blob([pdfBytes], { type: 'application/pdf' });
        const url = URL.createObjectURL(pdfBlob);
        const downloadOption = localStorage.getItem('downloadOption');

        const filenameInput = document.getElementById('filename-input');

        let inputArr = filenameInput.value.split('.');

        if (inputArr !== null && inputArr !== undefined && inputArr.length > 0) {

            inputArr = inputArr.filter(n => n); // remove all empty strings, nulls or undefined

            if (inputArr.length > 1) {
                inputArr.pop(); // remove right part after last dot
            }

            filenameInput.value = inputArr.join('');
            this.filename = filenameInput.value;
        }

        if (!filenameInput.value.includes('.pdf')) {
            filenameInput.value = filenameInput.value + '.pdf';
            this.filename = filenameInput.value;
        }

        if (downloadOption === 'sameWindow') {
            // Open the file in the same window
            window.location.href = url;
        } else if (downloadOption === 'newWindow') {
            // Open the file in a new window
            window.open(url, '_blank');
        } else {
            // Download the file
            this.downloadLink = document.createElement('a');
            this.downloadLink.id = 'download-link';
            this.downloadLink.href = url;
            // downloadLink.download = this.fileName ? this.fileName : 'managed.pdf';
            // downloadLink.download = this.fileName;
            this.downloadLink.setAttribute('download', this.filename ? this.fileName : 'managed.pdf');
            this.downloadLink.setAttribute('target', '_blank');
            this.downloadLink.onclick = this.setDownloadAttribute;
            this.downloadLink.click();
        }
    }

    setDownloadAttribute() {
        this.downloadLink.setAttribute("download", this.filename ? this.filename : 'managed.pdf');
    }

    updateFilename() {
       const filenameInput = document.getElementById('filename-input');
        const downloadBtn = document.getElementById('export-button');

        if (filenameInput.value === "") {
            downloadBtn.disabled = true;
            return;
        }

        downloadBtn.disabled = false;
        this.filename = filenameInput.value;
    }

    preventIllegalChars(e) {
        // const filenameInput = document.getElementById('filename-input');
        //
        // filenameInput.value = filenameInput.value.replace('.pdf', '');
        //
        // // prevent .
        // if (filenameInput.value.includes('.')) {
        //     filenameInput.value.replace('.','');
        // }
    }
}

export default PdfContainer;
