const path = require('path');
const fs = require('fs');

function Media()
{
}

function MediaStruct(i) {
    this.path = i.path;
    this.fileName = path.parse(i.path).name;
    this.md5sum = i.md5sum;
    this.date = i.date;
    this.meta = {};
    this.tags = [];
}

MediaStruct.prototype.pushMeta = function(key, value) {
    if (key && value && !this.meta[key])
        this.meta[key] = value;
}

MediaStruct.prototype.pushTag = function(tag) {
    if (tag && this.tags.indexOf(tag) === -1)
        this.tags.push(tag);
}

MediaStruct.prototype.HaveAccess = function(accessList) {
    if (!fs.existsSync(this.path))
        return false;
    accessList = accessList || {};
    for (let i in accessList) {
    }
    return true;
}

function reduceReqToMediaStruct(acc, i) {
    let obj = acc[i.md5sum] = acc[i.md5sum] || new MediaStruct(i);
    obj.pushMeta(i.metaKey, i.metaValue);
    obj.pushTag(i.mediaTag);
    return acc;
}

module.exports.fetchOne = async function(app, md5sum, accessList) {
    let result = ((await app.databaseHelper.runSql(`
        select mediaFile.path, mediaFile.md5sum, mediaFile.date,
        mediaMeta.key as metaKey, mediaMeta.value as metaValue,
        mediaTag.tag as mediaTag
        from mediaFile
        left join mediaMeta on mediaMeta.md5sum=mediaFile.md5sum
        left join mediaTag on mediaTag.md5sum=mediaFile.md5sum
        where mediaFile.md5sum=?`, md5sum)) || []).reduce(reduceReqToMediaStruct, {})[md5sum] || null;
    return result?.HaveAccess(accessList) ? result : null;
}

module.exports.fetchMedias = async function(app, startTs, count) {
    let result = ((await app.databaseHelper.runSql(`
        select mediaFile.path, mediaFile.md5sum, mediaFile.date,
        mediaMeta.key as metaKey, mediaMeta.value as metaValue,
        mediaTag.tag as mediaTag
        from mediaFile
        left join mediaMeta on mediaMeta.md5sum=mediaFile.md5sum
        left join mediaTag on mediaTag.md5sum=mediaFile.md5sum
        where mediaFile.md5sum in
            (select md5sum from mediaFile `
            +(startTs ? "where date <? " : "")
            +"order by date desc limit ?)", startTs ? [startTs, count] : [count])) || [])
    .reduce(reduceReqToMediaStruct, {});

    result = Object.keys(result).map(i => result[i]).sort((a, b) => b.date-a.date);
    return result;
};

module.exports.fetchMediasWithAccess = async function(app, startTs, count, access) {
    let result = [];
    let lastTs = startTs;

    while (result.length < count) {
        let tmp = await module.exports.fetchMedias(app, lastTs, 25);
        if (!tmp.length)
            return result;
        lastTs = tmp[tmp.length-1].date;
        tmp = tmp.filter(i => i.HaveAccess(access));
        if (tmp.length)
            result = result.concat(tmp);
    }
    return result.slice(0, count);
};

module.exports.getMediaRange = async function(app) {
    let result = await app.databaseHelper.runSql("select min(date) as _min, max(date) as _max from mediaFile");
    return [ result?.[0]?._min || 0, result?.[0]?._max || 0 ];
}