70 lines
2.5 KiB
JavaScript
70 lines
2.5 KiB
JavaScript
function createConversationPager({ loadPage }) {
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let state = { comments: [], page: 1, older_page: null, total: 0 };
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let olderRequest = null;
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const validComments = comments => Array.isArray(comments)
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? comments.filter(comment => comment && Number.isInteger(comment.id))
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: [];
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const unique = comments => {
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const seen = new Set();
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return comments.filter(comment => {
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if (seen.has(comment.id)) return false;
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seen.add(comment.id);
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return true;
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}).sort((left, right) => {
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const leftTime = Date.parse(left.created_at || '');
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const rightTime = Date.parse(right.created_at || '');
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if (Number.isFinite(leftTime) && Number.isFinite(rightTime) && leftTime !== rightTime) {
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return leftTime - rightTime;
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}
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return left.id - right.id;
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});
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};
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const snapshot = () => ({ ...state, comments: state.comments.map(comment => ({ ...comment })) });
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return {
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reset(page) {
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const comments = unique(validComments(page?.comments));
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state = {
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comments,
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page: Number.isInteger(page?.page) ? page.page : 1,
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older_page: Number.isInteger(page?.older_page) ? page.older_page : null,
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total: Number.isInteger(page?.total) ? Math.max(page.total, comments.length) : comments.length,
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};
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olderRequest = null;
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return snapshot();
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},
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snapshot,
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loadOlder() {
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if (olderRequest) return olderRequest;
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if (!Number.isInteger(state.older_page)) return Promise.resolve(snapshot());
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const requestedPage = state.older_page;
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olderRequest = Promise.resolve(loadPage(requestedPage)).then(page => {
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state = {
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comments: unique(validComments(page?.comments).concat(state.comments)),
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page: Number.isInteger(page?.page) ? page.page : requestedPage,
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older_page: Number.isInteger(page?.older_page) ? page.older_page : null,
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total: Number.isInteger(page?.total) ? Math.max(page.total, state.comments.length) : state.total,
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};
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return snapshot();
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}).finally(() => { olderRequest = null; });
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return olderRequest;
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},
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append(comment) {
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if (!comment || !Number.isInteger(comment.id)) return snapshot();
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if (!state.comments.some(existing => existing.id === comment.id)) {
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state = {
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...state,
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comments: state.comments.concat(comment),
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total: Math.max(state.total + 1, state.comments.length + 1),
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};
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}
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return snapshot();
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},
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};
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}
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if (typeof module !== 'undefined' && module.exports) module.exports = createConversationPager;
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