'use strict';

const config = require('config');
const omit = require('object.omit');

const dissectLink = require('../dissectLink.js');
const hashPost = require('./hashPost.js');

const { isAfter, isBefore, isEqual } = require('date-fns');
const logger = require('../logger')(__filename);

function report(curatedPosts, indexed, user, args) {
    const {
        indexedUpdated, tooOldCount, tooRecentCount, beforeIndexedCount, afterIndexedCount, requestedIgnored, duplicates,
    } = curatedPosts;

    if (indexedUpdated.length > 0) {
        logger.info(`Ignoring ${indexedUpdated.length} indexed posts for '${user.name}'`);
    }

    if (requestedIgnored.length > 0) {
        logger.info(`Ignoring ${requestedIgnored.length} posts because their IDs are specified to be ignored for '${user.name}'`);
    }

    if (tooOldCount > 0) {
        logger.info(`Ignoring ${tooOldCount} older posts for '${user.name}' for specified date limit '${args.after}'`);
    }

    if (tooRecentCount > 0) {
        logger.info(`Ignoring ${tooRecentCount} newer posts for '${user.name}' for specified date limit '${args.before}'`);
    }

    if (beforeIndexedCount > 0) {
        logger.info(`Ignoring ${beforeIndexedCount} posts older than the ${args.afterIndexed} indexed post (${indexed[args.afterIndexed].id}, ${indexed[args.afterIndexed].date}) for '${user.name}'`);
    }

    if (afterIndexedCount > 0) {
        logger.info(`Ignoring ${afterIndexedCount} posts newer than the ${args.beforeIndexed} indexed post (${indexed[args.beforeIndexed].id}, ${indexed[args.beforeIndexed].date}) for '${user.name}'`);
    }

    if (duplicates.length > 0) {
        logger.info(`Ignoring ${duplicates.length} duplicate posts for '${user.name}'`);
    }
}

function curatePost(acc, post, user, index, indexed, ignoreIds, processed, args) {
    const host = dissectLink(post.url);
    const permalink = `https://reddit.com${post.permalink}`;

    const curatedPost = {
        id: post.id,
        index,
        title: post.title,
        text: post.selftext,
        user: omit(user, ['posts']),
        permalink,
        url: post.url,
        datetime: new Date(post.created_utc * 1000),
        subreddit: post.subreddit.display_name,
        score: post.score,
        preview: post.preview ? post.preview.images.map(image => image.source) : null,
        host,
        direct: post.direct,
        comments: post.comments,
        hash: hashPost(post),
    };

    if (indexed.entries.length) {
        const indexedPost = indexed.entries.find(entry => entry.id === post.id);

        if (indexedPost && !args.redownload) {
            curatedPost.previewFallback = indexedPost.preview;

            return { ...acc, indexedUpdated: [...acc.indexedUpdated, curatedPost] };
        }

        if (args.afterIndexed && (isBefore(curatedPost.datetime, indexed[args.afterIndexed].date) || isEqual(curatedPost.datetime, indexed[args.afterIndexed].date))) {
            return { ...acc, beforeIndexedCount: acc.beforeIndexedCount + 1 };
        }

        if (args.beforeIndexed && (isAfter(curatedPost.datetime, indexed[args.beforeIndexed].date) || isEqual(curatedPost.datetime, indexed[args.beforeIndexed].date))) {
            return { ...acc, afterIndexedCount: acc.afterIndexedCount + 1 };
        }
    }

    if (args.after && (isBefore(curatedPost.datetime, args.after) || isEqual(curatedPost.datetime, args.after))) {
        return { ...acc, tooOldCount: acc.tooOldCount + 1 };
    }

    if (args.before && (isAfter(curatedPost.datetime, args.before) || isEqual(curatedPost.datetime, args.before))) {
        return { ...acc, tooRecentCount: acc.tooRecentCount + 1 };
    }

    // cut-off at limit, but don't count posts requested directly by ID
    if (acc.posts.length >= args.limit && !post.direct) {
        return acc;
    }

    const ignoring = args.ignore ? args.ignore.find(prop => post[prop]) : null;

    if (ignoring) {
        logger.verbose(`Ignoring ${ignoring} post '${post.title}' (${permalink})`);

        return acc;
    }

    if (host) {
        const hostIncludes = args.include && !args.include.includes(host.label);
        const hostExcluded = args.exclude && args.exclude.includes(host.label);

        if (ignoreIds.has(String(host.id).toLowerCase())) {
            return { ...acc, requestedIgnored: [...acc.requestedIgnored, curatedPost] };
        }

        if (hostIncludes || hostExcluded) {
            logger.info(`Ignoring source '${host.label}' from post '${post.url}' (${permalink})`);

            return acc;
        }

        if (config.fetch.avoidDuplicates && processed.has(host.id)) {
            logger.verbose(`Ignoring duplicate content '${post.url}' (cross-post, repost or superfluous --post ID) (${permalink})`);

            return { ...acc, duplicates: [...acc.duplicates, curatedPost] };
        }

        processed.add(host.id);
    }

    return {
        ...acc,
        processed,
        posts: [
            ...acc.posts,
            curatedPost,
        ],
    };
}

const curatePosts = (userPosts, ignoreIdsArray, args) => Object.values(userPosts).reduce((accPosts, user) => {
    const processed = new Set();
    const ignoreIds = new Set(ignoreIdsArray.map(postId => String(postId).toLowerCase()));
    const indexedByDate = user.indexed.original.sort((entryA, entryB) => new Date(entryA.date) - new Date(entryB.date));

    const indexed = {
        entries: indexedByDate,
        oldest: indexedByDate.slice(0, 1)[0],
        latest: indexedByDate.slice(-1)[0],
    };

    const curatedPosts = user.posts.reduce((accUserPosts, post, index) => curatePost(accUserPosts, post, user, index, indexed, ignoreIds, processed, args), {
        posts: [],
        indexedUpdated: [],
        requestedIgnored: [],
        duplicates: [],
        duplicateCount: 0,
        tooOldCount: 0,
        tooRecentCount: 0,
        beforeIndexedCount: 0,
        afterIndexedCount: 0,
    });

    report(curatedPosts, indexed, user, args);

    const indexedOriginal = user.indexed.original.filter(entry => !curatedPosts.indexedUpdated.find(post => post.id === entry.id));

    return {
        ...accPosts,
        [user.name]: {
            ...user,
            posts: curatedPosts.posts,
            indexed: {
                profile: user.indexed.profile,
                original: indexedOriginal,
                updated: curatedPosts.indexedUpdated,
                ignored: curatedPosts.requestedIgnored,
                oldest: indexed.oldest,
                latest: indexed.latest,
            },
        },
    };
}, {});

module.exports = curatePosts;