#!/usr/bin/env node
const stdin = process.stdin
const stdout = process.stdout

let page
let history = []
let scroll = 0

stdin.setRawMode(true)
stdout.write('\033[2J\033[H\033[?25l')
stdin.resume()
stdin.setEncoding( 'utf8' )

stdin.on( 'data',async function( key ){
    switch(key){
        case 'q':
        case '\u0003':{
            stdout.write('\033[?25h')
            stdin.setRawMode(false)
            process.exit();
            break
        }
        case 'j':{
            page.activeLink++
            if(page.activeLink===page.links.length) page.activeLink--
            render()
            break
        }
        case 'k':{
            page.activeLink--
            if(page.activeLink===-1) page.activeLink = 0
            render()
            break
        }
        case 'b':{
            if(history.length){
                scroll = 0
                page = history.pop()
                render()
            }
            break
        }
        case 'h':{
            scroll--
            if(scroll<0)scroll=0
            render()
            break
        }
        case 'l':{
            scroll++
            if(scroll===page.markup.length)scroll--
            render()
            break
        }
        case "\r":{
            scroll = 0
            history.push(page)
            await load(page.links[page.activeLink])
            render()
            break
        }
    }
})

async function load(id){
    let response = await fetch('https://pastebin.com/raw/'+id)
    let text = await response.text()
    let markup = []
    let links = []

    for(let line of text.split('\r\n')){
        if(line[0] === '#'){
            markup.push(['header', line.substr(1)])
        }else if(line[0] === '>'){
            let words = line.substr(1).split(' ')
            let address = words.shift()
            links.push(address)
            markup.push(['link', words.join(' '), address])
        }else if(line[0] === ' '){
            markup.push(['code',line])
        }else{
            markup.push(['text', line])
        }
    }
    page = {markup,activeLink:0,links,id}
}

function render(){
    let rows = 0
    stdout.write('\033[2J\033[H')
    let linkscounter = 0
    for(let element of page.markup.slice(scroll)){
        let [type,text] = element
        let height = Math.ceil(text.length/stdout.columns)
        if(rows+height>stdout.rows) text = text.substr(0,(stdout.rows-rows)*stdout.columns)
        rows += height
        switch(type){
            case 'header':{
                stdout.write('\033[1m'+text+'\033[0m\n')
                break
            }
            case 'link':{
                let style = linkscounter === page.activeLink ? '\033[30;42m' : '\033[32m'
                stdout.write(style+text+'\033[0m\n')

                linkscounter++
                break
            }
            case 'code':{
                stdout.write('\033[36m'+text+'\033[0m\n')
                break
            }
            default: console.log(text)
        }
        if(rows === stdout.rows) break
    }
}



load(process.argv[2]).then(_=>{
    render()
    setInterval(render,500)
})