'use strict';

var iframeObservers = new WeakMap();

document.addEventListener(
    'DOMContentLoaded',
    function () {
        initializeEmailList();
    }
);

function initializeEmailList() {
    var emailItems =
        document.querySelectorAll('.email-item');

    emailItems.forEach(function (item) {
        var summary =
            item.querySelector('.email-summary');

        var downloadButton =
            item.querySelector('.download-icon');

        if (summary) {
            summary.addEventListener(
                'click',
                function (event) {
                    if (
                        event.target.closest(
                            '.download-icon'
                        )
                    ) {
                        return;
                    }

                    toggleEmail(item);
                }
            );

            summary.addEventListener(
                'keydown',
                function (event) {
                    if (
                        event.key !== 'Enter' &&
                        event.key !== ' '
                    ) {
                        return;
                    }

                    if (
                        event.target.closest(
                            '.download-icon'
                        )
                    ) {
                        return;
                    }

                    event.preventDefault();

                    toggleEmail(item);
                }
            );
        }

        if (downloadButton) {
            downloadButton.addEventListener(
                'click',
                function (event) {
                    event.stopPropagation();

                    var id = item.dataset.id;

                    if (!id) {
                        console.error(
                            'Email ID is missing'
                        );

                        return;
                    }

                    downloadEmail(
                        event,
                        id
                    );
                }
            );
        }
    });
}

function toggleEmail(item) {
    var id = item.dataset.id;

    if (!id) {
        console.error(
            'Email ID is missing'
        );

        return;
    }

    var summary =
        item.querySelector('.email-summary');

    var detail =
        item.querySelector('.email-detail');

    var toggleIcon =
        item.querySelector('.toggle');

    var iframe =
        item.querySelector(
            '.email-content-frame'
        );

    if (!detail || !iframe) {
        console.error(
            'Email UI elements are missing for:',
            id
        );

        return;
    }

    var isHidden =
        detail.classList.contains('hidden');

    if (isHidden) {
        detail.classList.remove('hidden');

        if (toggleIcon) {
            toggleIcon.classList.add(
                'rotated'
            );
        }

        if (summary) {
            summary.setAttribute(
                'aria-expanded',
                'true'
            );
        }

        loadEmailContent(
            id,
            iframe
        );
    } else {
        detail.classList.add('hidden');

        if (toggleIcon) {
            toggleIcon.classList.remove(
                'rotated'
            );
        }

        if (summary) {
            summary.setAttribute(
                'aria-expanded',
                'false'
            );
        }
    }
}

function loadEmailContent(id, iframe) {
    if (
        iframe.dataset.loaded === 'true'
    ) {
        resizeIframe(iframe);
        return;
    }

    if (
        iframe.dataset.loading === 'true'
    ) {
        return;
    }

    iframe.dataset.loading = 'true';

    fetch(
        '/api/view?id=' +
        encodeURIComponent(id),
        {
            method: 'GET',
            credentials: 'same-origin'
        }
    )
        .then(function (response) {
            handleUnauthorized(response);

            if (!response.ok) {
                throw new Error(
                    'HTTP error ' +
                    response.status
                );
            }

            return response.text();
        })
        .then(function (data) {
            resetIframeObserver(iframe);

            writeEmailToIframe(
                iframe,
                data
            );

            iframe.dataset.loaded =
                'true';

            delete iframe.dataset.loading;

            resizeIframe(iframe);
        })
        .catch(function (error) {
            delete iframe.dataset.loading;

            // При 401 уже выполняется redirect.
            if (
                error &&
                error.message ===
                    'Session expired'
            ) {
                return;
            }

            resetIframeObserver(iframe);

            writeErrorToIframe(
                iframe,
                error.message
            );

            console.error(
                'Failed to load email:',
                id,
                error
            );
        });
}

function handleUnauthorized(response) {
    if (response.status !== 401) {
        return;
    }

    window.location.href = '/login';

    throw new Error(
        'Session expired'
    );
}

function writeEmailToIframe(
    iframe,
    emailBody
) {
    var doc =
        iframe.contentWindow.document;

    doc.open();

    doc.write(
        '<!DOCTYPE html>' +

        '<html>' +

        '<head>' +

        '<meta charset="UTF-8">' +

        '<meta ' +
            'name="viewport" ' +
            'content="width=device-width, initial-scale=1.0"' +
        '>' +

        '<base target="_blank">' +

        '<style>' +

        'html {' +
            'margin:0 !important;' +
            'padding:0 !important;' +
            'background:white !important;' +
        '}' +

        'body {' +
            'margin:0 !important;' +
            'padding:15px !important;' +
            'font-family:monospace !important;' +
            'font-size:12px !important;' +
            'line-height:1.4 !important;' +
            'background:white !important;' +
            'color:#333 !important;' +
            'overflow-wrap:anywhere !important;' +
        '}' +

        '* {' +
            'box-sizing:border-box !important;' +
            'max-width:100% !important;' +
        '}' +

        'img {' +
            'max-width:100% !important;' +
            'height:auto !important;' +
        '}' +

        'table {' +
            'max-width:100% !important;' +
        '}' +

        'pre {' +
            'margin:0 !important;' +
            'font-family:inherit !important;' +
            'white-space:pre-wrap !important;' +
            'overflow-wrap:anywhere !important;' +
        '}' +

        'a {' +
            'color:#2563eb !important;' +
            'text-decoration:underline !important;' +
        '}' +

        'a:visited {' +
            'color:#7c3aed !important;' +
        '}' +

        'a:hover {' +
            'color:#1d4ed8 !important;' +
        '}' +

        '</style>' +

        '</head>' +

        '<body>' +
            emailBody +
        '</body>' +

        '</html>'
    );

    doc.close();
}

function writeErrorToIframe(
    iframe,
    message
) {
    var doc =
        iframe.contentWindow.document;

    doc.open();

    doc.write(
        '<!DOCTYPE html>' +

        '<html>' +

        '<head>' +
            '<meta charset="UTF-8">' +
        '</head>' +

        '<body style="' +
            'padding:15px;' +
            'font-family:monospace;' +
            'font-size:12px;' +
            'color:#b91c1c;' +
        '">' +

        'Error loading email: ' +
        escapeHTML(message) +

        '</body>' +

        '</html>'
    );

    doc.close();

    resizeIframe(iframe);
}

function resetIframeObserver(iframe) {
    var observer =
        iframeObservers.get(iframe);

    if (observer) {
        observer.disconnect();

        iframeObservers.delete(
            iframe
        );
    }
}

function resizeIframe(iframe) {
    if (
        !iframe ||
        !iframe.contentWindow
    ) {
        return;
    }

    try {
        var doc =
            iframe.contentWindow.document;

        if (!doc || !doc.body) {
            return;
        }

        updateIframeHeight(
            iframe,
            doc
        );

        if (
            typeof ResizeObserver ===
            'undefined'
        ) {
            return;
        }

        var existing =
            iframeObservers.get(iframe);

        if (existing) {
            return;
        }

        var observer =
            new ResizeObserver(
                function () {
                    try {
                        var currentDoc =
                            iframe
                                .contentWindow
                                .document;

                        updateIframeHeight(
                            iframe,
                            currentDoc
                        );
                    } catch (error) {
                        // Iframe may have been replaced.
                    }
                }
            );

        observer.observe(
            doc.body
        );

        iframeObservers.set(
            iframe,
            observer
        );
    } catch (error) {
        console.warn(
            'Cannot resize email iframe:',
            error
        );
    }
}

function updateIframeHeight(
    iframe,
    doc
) {
    if (!doc || !doc.body) {
        return;
    }

    var bodyHeight =
        doc.body.scrollHeight;

    var htmlHeight =
        doc.documentElement
            ? doc.documentElement.scrollHeight
            : 0;

    var height = Math.max(
        bodyHeight,
        htmlHeight,
        180
    );

    iframe.style.height =
        height + 20 + 'px';
}

function downloadEmail(
    event,
    id
) {
    var button =
        event.currentTarget;

    if (!id) {
        return;
    }

    var originalTransform =
        button.style.transform;

    var originalOpacity =
        button.style.opacity;

    button.disabled = true;

    button.style.transform =
        'scale(0.8)';

    button.style.opacity =
        '0.5';

    fetch(
        '/api/download?id=' +
        encodeURIComponent(id),
        {
            method: 'GET',
            credentials: 'same-origin'
        }
    )
        .then(function (response) {
            handleUnauthorized(response);

            if (!response.ok) {
                throw new Error(
                    'HTTP error ' +
                    response.status
                );
            }

            return Promise.all([
                response.blob(),
                Promise.resolve(
                    getDownloadFilename(
                        response,
                        id
                    )
                )
            ]);
        })
        .then(function (result) {
            var blob = result[0];
            var filename = result[1];

            var objectURL =
                URL.createObjectURL(blob);

            var link =
                document.createElement('a');

            link.href = objectURL;
            link.download = filename;

            document.body.appendChild(
                link
            );

            link.click();
            link.remove();

            window.setTimeout(
                function () {
                    URL.revokeObjectURL(
                        objectURL
                    );
                },
                1000
            );
        })
        .catch(function (error) {
            if (
                error &&
                error.message ===
                    'Session expired'
            ) {
                return;
            }

            console.error(
                'Failed to download email:',
                id,
                error
            );

            window.alert(
                'Failed to download email'
            );
        })
        .finally(function () {
            button.disabled = false;

            button.style.transform =
                originalTransform;

            button.style.opacity =
                originalOpacity;
        });
}

function getDownloadFilename(
    response,
    id
) {
    var contentDisposition =
        response.headers.get(
            'Content-Disposition'
        );

    if (contentDisposition) {
        var match =
            contentDisposition.match(
                /filename="([^"]+)"/i
            );

        if (match && match[1]) {
            return match[1];
        }
    }

    var parts = id.split('/');

    if (parts.length > 0) {
        return parts[
            parts.length - 1
        ];
    }

    return 'email.eml';
}

function escapeHTML(value) {
    return String(value)
        .replace(/&/g, '&amp;')
        .replace(/</g, '&lt;')
        .replace(/>/g, '&gt;')
        .replace(/"/g, '&quot;')
        .replace(/'/g, '&#039;');
}