"use strict";

const pageItemBox = document.getElementById('item-box')
const headerSub = document.getElementById('header-sub')
const params = new URLSearchParams(document.location.search)

// for top listing
let items = [] // shuld be an array of items id
let currentItem = -1

// for newest listing
let newMode = params.get('order') == 'new'
let endItem // for the later new items. new items will be fetch until this item
let maxItem
let new_loader_id

// for the api requests
let loadedItems = 0
let loader_id
let timer = 100 // how many request pre minute

// for item query
let isQuery = params.get('id') != null

const itemType = {
    job: 'job',         // list
    story: 'story',     // list
    comment: 'comment',
    poll: 'poll',       // list
    pollopt: 'pollopt'
}

async function fetchStories() {
    const req = await fetch('https://hacker-news.firebaseio.com/v0/topstories.json')

    req.json().then(resolve => {
        items = resolve
        currentItem = 0
    })
}

async function fetchMaxItem() {
    const req = await fetch('https://hacker-news.firebaseio.com/v0/maxitem.json')

    return req.json()
}

function loadItems() {

    const shouldLoad = () => {
        const maxScroll = document.documentElement.scrollHeight - document.documentElement.clientHeight 
        return (currentItem < items.length) && window.scrollY > maxScroll - 100 || maxScroll == 0
    }

    if (loader_id || !shouldLoad()) {
        return
    }

    loader_id = setInterval(async () => {

        if (!shouldLoad()) {
            loader_id = clearInterval(loader_id)

            if (newMode && !new_loader_id) {
                new_loader_id = setInterval(loadFresh, 5e3)
            }

            return
        }

        const itemId = newMode ? maxItem-- : items[currentItem++]

        try {
            const item = await getItem(itemId)
            makeItemListing(item)

        } catch (e) {
            console.log(`[loadItems] got error ${e}`)
        }

    }, timer)
}


function getItem(id) {
    const url = `https://hacker-news.firebaseio.com/v0/item/${id}.json`

    try {
        return fetch(url).then(response => response.json().then(obj => obj))
    } catch (e) {
        console.log(`[getItem] failed to fetch item ${id}`)
        return
    }
}


function makeItemListing(itemObj) {

    if (itemObj === null || itemObj === undefined) {
        clearInterval(loader_id)
        throw new Error(`[makeItemListing] null or undefined object`)
    }

    if (itemObj.deleted || itemObj.dead || itemObj.title == "[deleted]") {
        console.debug(`[makeItemListing] Deleted item: ${itemObj.id}`)
        return
    }

    if (itemObj.type == itemType.comment || itemObj.type == itemType.pollopt) {
        console.debug(`[makeItemListing] Comment or Poll Option item: ${itemObj.id}`)
        return
    }

    const id = itemObj.id
    const title = itemObj.title
    const url = itemObj.url

    const points = itemObj.score
    const author = itemObj.by
    const time = itemObj.time
    const date = timeSince(itemObj.time)
    const comments = itemObj.descendants

    const match = url && url.match(/https?:\/\/([^\/:]+)/)
    const hostname = match && match[1]

    let subtitle = `${points} points by ${author} ${date} ago`

    if (itemObj.type != itemType.job) {
        subtitle += ` | ${comments} comments`
    } else {
        console.log(`[makeItemListing] job item ${title}`)
    }

    const element_string =`
    <div class="block">
      <div class="columns">
        <div class="column is-narrow">
          <h4 class="title is-4">${title} <a href="${url}">(${hostname})</a></h4>
          <p class="subtitle is-5">${subtitle}</p>
        </div>
        <div class="column is-narrow is-center">
          <span class="icon is-small is-right" style="height: 100%">
            <i class="fas fa-arrow-right"></i>
          </span>
        </div>
      </div>
    </div>
    `
    const item = document.createElement('a')
    item.href = "index.html?id=" + id

    // i got lazy
    item.time = time
    item.points = points
    item.comments = comments
    item.author = author

    item.innerHTML = element_string

    if (url === undefined || hostname === undefined) {
        const header = item.getElementsByClassName('title')[0]
        header.innerHTML = title
    }

    const children = Array.from(pageItemBox.childNodes)

    for (const c of children) {
        if (typeof c == 'object' && c.time < item.time) {
            try {
                pageItemBox.insertBefore(item, c)
                return
            } catch (error) {
                console.log(error)
                console.log(c)
                clearInterval(loader_id)
            }
        }
    }

    pageItemBox.appendChild(item)
}

function timeSince(date) {

    const now = Date.now() / 1000
    const seconds = Math.floor(now - date)

    if (seconds > 31536000) {
        return Math.floor(seconds / 31536000) + " years"
    }

    if (seconds > 2592000) {
        return Math.floor(seconds / 2592000) + " months"
    }

    if (seconds > 86400) {
        return Math.floor(seconds / 86400) + " days"
    }

    if (seconds > 3600) {
        return Math.floor(seconds / 3600) + " hours"
    }

    if (seconds > 60) {
        return Math.floor(seconds / 60) + " minutes"
    }

    return Math.floor(seconds) + " seconds"
}


async function itemPage() {

    headerSub.innerHTML = ''

    const item = await getItem(params.get('id'))

    if (item == null || item == undefined) {
        const element_string =`
        <div class="block">
          <div class="columns">
            <div class="column is-narrow">
              <h4 class="title is-4">Something went Bad :(</a></h4>
              <p class="subtitle is-5">Couldn't get your result from the api</p>
            </div>
          </div>
        </div>
        <sep>
        `
        const item = document.createElement('div')
        item.innerHTML = element_string

        pageItemBox.appendChild(item)
    }

    const type = item.type
    let target = pageItemBox

    if (type != itemType.comment && type != itemType.pollopt) {
        if (item.url) {
            headerSub.innerHTML = `<a href=${item.url}>${item.title}</a> | ${item.score} points`
        } else {
            headerSub.innerHTML = `${item.title} | ${item.score} points`
        }
    }

    if (item.type == itemType.poll) {
        await loadPollOpt(item.parts)
    } else if (type == itemType.pollopt){
        return loadPollOpt([item.id])
    }

    if (!item.kids) {
        console.log(type)
        return
    }

    if (type == itemType.comment) {
        loadCommnets([item.id], target)
    } else {
        loadCommnets(item.kids, target)
    }

}

async function loadPollOpt(opts) {

    for (const id of opts) {

        const item = await getItem(id)

        if (!item || !item.text || !item.score) {
            continue
        }

        const element_string =`
        <div class="columns">
          <div class="column is-narrow is-center">
            <span class="icon is-small is-left" style="height: 100%">
              <i class="fas fa-arrow-up">&nbsp;${item.score}</i>
            </span>
          </div>
          <div class="column is-narrow">
            <h4 class="title is-4">${item.text}</h4>
          </div>
        </div>
        `

        const element = document.createElement('div')
        element.className = 'block'
        element.innerHTML = element_string

        pageItemBox.appendChild(element)
    }

    pageItemBox.innerHTML += '<hr>'
}


const sleep = (ms) => new Promise(resolve => {
    const reachedEnd = () => {
        const maxScroll = document.documentElement.scrollHeight - document.documentElement.clientHeight 
        return window.scrollY >= maxScroll - 100
    }

    const waitForScroll = () => {
        if (!reachedEnd()) {
            return
        }

        resolve()
        document.removeEventListener('scroll', waitForScroll)
    }

    if (reachedEnd()) {
        setTimeout(resolve, ms)
    } else {
        document.addEventListener('scroll', waitForScroll)
    }
})

async function loadCommnets(ids, target) {

    const message = (msg) => `
    <div class="card-content">
      <div class="content">
        ${msg}
      </div>
    </div>
    `

    for (const id of ids) {
        await sleep(timer)

        try {

            const itemObj = await getItem(id)
            if (itemObj == undefined || itemObj.type != itemType.comment || !itemObj.text) {
                continue
            }

            const item = document.createElement('div')
            item.className = 'card'
            item.innerHTML = message(itemObj.text)

            target.appendChild(item)

            if (itemObj.kids && itemObj.kids.length > 0) {
                const mainBox = item.getElementsByClassName('content')[0]
                const subBox = document.createElement('div')

                subBox.className = 'card'

                mainBox.innerHTML += '<br>'
                mainBox.appendChild(subBox)

                await loadCommnets(itemObj.kids, subBox)
            }

        } catch (e) {
            console.log(`[loadCommnets] failed to load comment ${id}, error ${e}`)
        }
    }
}

async function loadPage() {

    if (isQuery) {
        return itemPage()
    }

    if (newMode) {
        maxItem = await fetchMaxItem()
        endItem = maxItem

    } else {
        await fetchStories()
    }

    loadItems()
    document.addEventListener('scroll', loadItems)
}

loadPage()

let switchBtn = document.getElementById('switch-btn')
if (newMode) {
    switchBtn.innerText = 'Top'
    switchBtn.className = 'button is-primary'
}

switchBtn.addEventListener("click", () => {
    if (newMode) {
        window.location.assign('index.html')
    } else {
        window.location.assign('index.html?order=new')
    }
})

// ================ new items section stuff ===================
let permission = 'denied'
let notificationBtn = document.getElementById('notification-btn')

notificationBtn.addEventListener("click", updatePermission)
function updatePermission() {

    if (!newMode) {
        notificationBtn.style.visibility = 'collapse'
        return
    }

    Notification.requestPermission().then(result => {
        permission = result
        notificationBtn.disabled = permission == 'denied'
    })
}
updatePermission()

async function notify(count) {

    if (count == 0) {
        return
    }

    new Notification("Clone Wars", { body: `${count} new Posts`})
}

async function loadFresh() {

    let newMax = endItem

    try {
        newMax = await fetchMaxItem()
    } catch (e) {
        console.log(`[loadFresh] got error ${e}`)
    }

    const newEnd = newMax

    if (newMax <= endItem) {
        return
    }

    console.log(`[loadFresh] New Items ${newMax - endItem}`)
    const count = pageItemBox.childElementCount

    let intervalId = setInterval(() => {

        if (newMax <= endItem) {
            endItem = newEnd
            notify(pageItemBox.childElementCount - count)
            clearInterval(intervalId)
            return
        }

        try {
            getItem(newMax--).then(item => {
                if (item) {
                    makeItemListing(item)
                }
            })

        } catch (e) {
            console.log(`[loadFresh] got error ${e}`)
        }


    }, timer)

}

if (!isQuery) {
    setInterval(() => Array.from(pageItemBox.getElementsByTagName('a')).map(c => {

        if (!c.time) {
            return
        }

        const sub = c.getElementsByClassName('subtitle')[0]

        const date = timeSince(c.time)
        const points = c.points
        const author = c.author
        const comments = c.comments

        let subtitle = `${points} points by ${author} ${date} ago`

        if (comments !== undefined) {
            subtitle += ` | ${comments} comments`
        }

        sub.innerHTML = subtitle
    }), 1e3)
}