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

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 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 importStylesheet(xsl: Node) {
    //Firefox does not seem to report XML parsing errors into the
    //exception tree. So we catch here, log, and return some friendly
    //error.
    try {
        const xsltProcessor = new XSLTProcessor();
        xsltProcessor.importStylesheet(xsl);
        return xsltProcessor;
    } catch (cause) {
        console.error(cause);
        throw new Error('Stylesheet parsing failed');
    }
}

async function createXSLTProcessor() {
    const doc = new DOMParser().parseFromString(xsl, "text/xml");
    return Promise.resolve(importStylesheet(doc));
    // return fetch(new URL("./MessageLog.xsl", import.meta.url))
    //     .then(resp => {
    //         if (resp.ok)
    //             return resp.text();
    //         else
    //             throw new Error(resp.status + ' ' + resp.statusText);
    //     })
    //     .then(str => new DOMParser().parseFromString(str, "text/xml"))
    //     .then(importStylesheet)
    //     .catch(cause => {
    //         throw new Error('Could not load XSL stylesheet', { cause });
    //     });
}

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));

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

function displayBackup(xsltProcessor: XSLTProcessor, file: File) {
    hideErrors();

    removeChildren(ui.chatDisplay);

    file.text().then(xmlText => {
        ui.currentlyViewing.innerText = file.name;
        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);
                processFragment();
            }
            catch (e) {
                if (e instanceof Error) {
                    displayNonFatalError('Could not load backup', e);
                }
            }
        } else {
            const err = new Error(errorNode.firstChild?.nodeValue || '');
            displayNonFatalError('Could not load backup', err);
        }

    });
}

function initEvents(xsltProcessor: XSLTProcessor) {
    ui.fileSelector.addEventListener("change", async (e) => {
        const target = e.currentTarget as HTMLInputElement | null;
        const file = target?.files?.[0];
        if (file) {
            displayBackup(xsltProcessor, file);
        } else {
            displayNonFatalError('Could not load file', new Error('No file found.'));
        }
    });
}

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');
        }
    });

    createXSLTProcessor()
        .then(initEvents)
        .then(_ => {
            showLoadingIndicator(false);
            showApplication(true);
        })
        .catch(ex => displayFatalError('Initialiation Failed', ex));
});