import * as bootstrap from 'bootstrap';
import xslContent from 'bundle-text:../xsl/MessageLog.xsl';
import * as ui from './ui';
import { db } from './db';

const xsltProcessor = createXSLTProcessor(xslContent)!;

function showApplication(toggle: boolean) {
    if (toggle) {
        ui.realBody.classList.remove('d-none');
    } else {
        ui.realBody.classList.add('d-none');
    }
}

function showLoadingIndicator(toggle: boolean) {
    if (toggle) {
        ui.loadingIndicator.classList.remove('d-none');
    } else {
        ui.loadingIndicator.classList.add('d-none');
    }
}

function showLoadedControls() {
    ui.noFileLoadedControls.classList.add('d-none');
    ui.noFileLoadedControls.classList.remove('d-md-block');
    ui.fileLoadedControls.classList.remove('d-none');
}

function displayError(errorDiv: HTMLElement, category: string, ex: Error) {
    console.error(ex);
    const errorHeading = errorDiv.querySelector('.alert-heading') as HTMLElement | null;

    //clear all error text, but not heading
    const errorMessages = errorDiv.querySelectorAll('span');
    errorMessages.forEach(message => errorDiv.removeChild(message));

    //add new message and show the error alert
    const errorSpan = document.createElement('span');
    errorSpan.innerText = ex.message;
    errorDiv.appendChild(errorSpan);

    if (errorHeading) {
        errorHeading.innerText = category;
    }
    errorDiv.classList.remove('d-none');
}

function displayFatalError(category: string, ex: Error) {
    showApplication(false);
    showLoadingIndicator(false);
    displayError(ui.fatalError, category, ex);
}

function displayNonFatalError(category: string, ex: Error) {
    showApplication(true);
    showLoadingIndicator(false);
    displayError(ui.nonFatalError, category, ex);
}

function hideErrors() {
    document
        .querySelectorAll('#fatal-error, #display-backup-error')
        .forEach(el => el.classList.add('d-none'));
}

function createXSLTProcessor(xmlStylesheet: string): XSLTProcessor | undefined {
    const doc = new DOMParser().parseFromString(xmlStylesheet, "text/xml");
    try {
        const xsltProcessor = new XSLTProcessor();
        xsltProcessor.importStylesheet(doc);
        return xsltProcessor;
    } catch (cause) {
        console.error(cause);
        displayFatalError('Initialiation Failed', new Error('Stylesheet parsing failed'));
    }
}

function removeChildren(element: HTMLElement) {
    while (element.hasChildNodes() && element.lastChild != null) {
        element.removeChild(element.lastChild);
    }
}

function checkOverflow(elem: HTMLElement) {
    const elemHeight = elem.scrollHeight;
    const parentHeight = elem.offsetHeight;
    return elemHeight > parentHeight;
}

function processFragment() {
    document
        .querySelectorAll('[data-bs-toggle="popover"]')
        .forEach(popover => new bootstrap.Popover(popover, { trigger: 'focus' }));

    document.querySelectorAll('.message-content div').forEach(div => {
        if (checkOverflow(div as HTMLElement)) {
            div.parentElement?.classList.add('overflow-icon');
        }
    });
}

async function saveToDatabase(filename: string, xml: string) {
    db.entries
        .put({ filename, backupData: xml })
        .catch(err => displayFatalError('Saving Failed', err));
}

function displayBackup(xsltProcessor: XSLTProcessor, filename: string, xmlText: string): boolean {
    hideErrors();
    removeChildren(ui.chatDisplay);
    showLoadedControls();

    const parser = new DOMParser();
    const xmlDoc = parser.parseFromString(xmlText, "text/xml");
    const errorNode = xmlDoc.querySelector('parsererror');

    if (!errorNode) {
        try {
            const fragment = xsltProcessor.transformToFragment(xmlDoc, document);
            ui.chatDisplay.appendChild(fragment);
            ui.currentlyViewing.value = filename;
            processFragment();
            return true;
        }
        catch (e) {
            if (e instanceof Error) {
                displayNonFatalError('Could not load backup', e);
            }
            return false;
        }
    } else {
        const err = new Error(errorNode.firstChild?.nodeValue || '');
        displayNonFatalError('Could not load backup', err);
        return false;
    }
}

function initEvents() {
    ui.loadPreviousButtons.forEach(button => button.addEventListener('click', async () => {
        await populateSavedBackups();
    }));

    ui.viewNewButtons.forEach(button => button.addEventListener('click', e => {
        ui.fileSelector.click();
        e.preventDefault();
    }));

    ui.fileSelector.addEventListener("change", async (e) => {
        const target = e.currentTarget as HTMLInputElement | null;
        const file = target?.files?.[0];

        if (file) {
            const xmlText = await file.text();
            if (displayBackup(xsltProcessor, file.name, xmlText)) {
                await saveToDatabase(file.name, xmlText);
            }
        } else {
            displayNonFatalError('Could not load file', new Error('No file found.'));
        }
    });
}

async function populateSavedBackups() {
    removeChildren(ui.previousBackupsList);
    const modal = new bootstrap.Modal('#previous-backups-modal');
    const entries = await db.entries.orderBy('filename').toArray();

    entries.forEach(entry => {
        const listItem = document.createElement('a');
        listItem.href = '#';
        listItem.dataset['filename'] = entry.filename;
        listItem.innerText = entry.filename;
        listItem.classList.add('list-group-item', 'list-group-item-action');

        listItem.addEventListener('click', async () => {
            const reloaded = await db.entries.get(entry.filename);
            if (reloaded) {
                displayBackup(xsltProcessor, reloaded.filename, reloaded.backupData);
            } else {
                displayNonFatalError('Internal Error', new Error('Backup data disappeared?!'));
            }
            modal.hide();
        });

        ui.previousBackupsList.appendChild(listItem);
    });

    modal.show();
}

window.addEventListener('DOMContentLoaded', async () => {
    window.addEventListener('resize', () => {
        if (window.innerWidth <= 500) {
            ui.chatDisplay.querySelector('table')?.classList.add('table-sm');
        } else {
            ui.chatDisplay.querySelector('table')?.classList.remove('table-sm');
        }
    });

    initEvents();
    showLoadingIndicator(false);
    showApplication(true);
});