// Config
const DEBUG = 0;
const CMD_PORT = "8888";
const TIMELINE_COLOR_CURSOR = "#FF8839";
const TIMELINE_COLOR_BG = "#2EB8E600";
// Timeline drag and drop elements default attributes
const tl_cont_attr = {id:"tl_cont", ondrop: "drop(event, this)", ondragover:"allow_drop(event)"};
const tl_drag_attr = {id:"tl_drag", draggable:"true", ondragstart:"drag(event, this)"};
//  Global object
window.currentUser = {
  scan_interval : 3000,
  status_all :  "Searching network for live hosts...",
  medias_status : {},
  freeze_timeline_update : 0,
};


function sleep(ms) {
    let delay = new Promise(function(resolve) {
	setTimeout(resolve, ms);
    });
    return delay ;
    // arrow notation equivalent
    // return new Promise(resolve => setTimeout(resolve, ms));
}


async function update_VLC_playlist(host) {
    // Update host's VLC playlist according to web UI timeline
    let media_count = document.getElementById(`timeline_${host}`).children.length;
    // Reversed loop
    for (let i=media_count, l=0; i>l; i--) {
	// Find current's timeline element children's 'media_id' value
	let to_shift = document.getElementById(`timeline_${host}`).children[i-1].children[0].getAttribute("media_id");
	console.log(to_shift + " : " + document.getElementById(`timeline_${host}`).children[i-1].children[0].innerText);
	// Move 'to_shift' after element with id '1' :
	// In VLC's playlist XML representation, the playlist node always gets id '1', so moving to that id
	// really means moving to the the very start of the playlist.
	send_ajax_cmd("/" + host + "/move/" + to_shift + "/1");
	await sleep(90);
    }
    // Un-freeze timeline update flag
    currentUser.freeze_timeline_update = 0;  
}


function find_target_index(element, index) {
    if (element == this) {
	return index + 1;
    }
    return 0;
}


function shift_elements(source_element, target_element) {
    // Shift elements in the timeline UI 
    //
    // Get a list of current element siblings
    let siblings_list = Array.from(source_element.parentElement.children);
    let siblings_list_slice;
    // Find indexes of source and target elements in the timeline
    let source_index = siblings_list.findIndex(find_target_index, source_element);
    let target_index = siblings_list.findIndex(find_target_index, target_element);
    let insert_at = 0;
    // Target element is on the left of the source element
    if (source_index < target_index){
	siblings_list_slice = siblings_list.slice(source_index + 1, target_index + 1);
	insert_at = source_index;
    } else {
    // Target element is on the right of the source element
	siblings_list_slice = siblings_list.slice(target_index, source_index );
	insert_at = target_index + 1;
    }
    // Shift elements according to insert_at
    for (let i=0, l=siblings_list_slice.length; i<l;i++){
	siblings_list[insert_at + i].appendChild(siblings_list_slice[i].children[0]);
    }
    return insert_at;
}


function allow_drop(event) {
    event.preventDefault();
}


function drag(event, source) {
    // Freeze timeline update flag
    currentUser.freeze_timeline_update = 1;
    event.dataTransfer.setData("text", event.target.id);
}


function drop(event, target_element) {
    // If the currently dragged element is dropped on another element, 
    // shift HTML elements in the timeline to the left or right from the target element.
    event.preventDefault();
    // Get dragged element id
    let dropped_id = event.dataTransfer.getData("text");
    let source_element = document.getElementById(dropped_id);
    let current_host = target_element.parentElement.id.split("_")[1];
    // Only shift if not dropping on self
    if (source_element.id != target_element.id) {
        let dropTarget = shift_elements(source_element.parentElement, target_element);
        //~ let dropTarget = shift_elements(currentUser.source_element, target_element);
        if (dropTarget) {
	    // Append dropped element to drop target.
            target_element.appendChild(source_element);
	    update_VLC_playlist(current_host);
	}
    }
    send_ajax_cmd("/" + current_host + "/list");
}


function adjust_timeline() {
    // Adapt timeline's UI elements to fit the width of their parent container.
    let timeline_div = document.querySelector('[id^="timeline_"]').children;
    let div_width = 100 / timeline_div.length;
    for (let i=0, l=timeline_div.length; i<l; i++) {
      timeline_div[i].style.width= div_width + "%";
    }
    return timeline_div.length;
}


function add_HTML_attr(id, attribute, val , child=-1) {
    // Add attribute 'attr' with value 'val' to the HTML element with id 'id'.
    // If child is other than -1, the attribute is applied to the HTML element's child at position 'child'
    let HTML_element = document.getElementById(id);
    if (child > -1){
	HTML_element = HTML_element.children[child];
    }
    let HTML_attr = document.createAttribute(attribute);
    HTML_attr.value = val;
    HTML_element.setAttributeNode(HTML_attr);
}


function add_HTML_element(type, attribute, meta=0, uid=0){
    // Add HTML element with type 'type' and attributes 'attribute'. 
    // 'attribute' should be a javascript object containing HTML attributes keys/values
    // 'meta' should be an array
    // 'uid' is used to make the HTML id attribute unique
    //
    let HTML_element = document.createElement(type);
    let HTML_attributes = Object.keys(attribute);
    for (let i=0, l=HTML_attributes.length; i<l; i++) {
	let new_attribute = document.createAttribute(HTML_attributes[i]);
	if(HTML_attributes[i] == "id") {
	    // HTML id needs to be unique
	    new_attribute.value = Object.values(attribute)[i] + uid;
	} else {
	    new_attribute.value = Object.values(attribute)[i];
	}
	HTML_element.setAttributeNode(new_attribute);
    }	
    // Set media_id attribute if metadata is provided
    if (meta) {
	let media_attribute = document.createAttribute("media_id");
	media_attribute.value = meta[0];
	HTML_element.setAttributeNode(media_attribute);
    }
    // Set filename as inner text 
    HTML_element.innerText = meta[1];
    return HTML_element;
}


function toggle_indicator(infos_array_element, property) {
    // Toggle element bg color
    toggle_state = 0;
    if (infos_array_element[property] == "true") { 
	document.getElementById(`${property}_ind_${infos_array_element.host}`).style.backgroundColor = "#78E738";
	toggle_state = 1;
    } else {
	document.getElementById(`${property}_ind_${infos_array_element.host}`).style.backgroundColor = "#A42000";
    }
    return toggle_state;
}


function update_status(infos_array_element) {
    if (infos_array_element.status) {
	document.getElementById("status_" + infos_array_element.host).innerHTML = infos_array_element.file + " <br/> " + infos_array_element.time + " / " + infos_array_element.leng;
	currentUser.medias_status[infos_array_element.id] = infos_array_element.pos;
	// Highlight currently playing element
	let timeline_medias_array = Array.from(document.querySelectorAll('[media_id]'));
	timeline_medias_array.forEach(function(media_element){
	    if ( media_element.getAttribute("media_id") == infos_array_element.id ) {
		let first_CSS_gradient_stop = infos_array_element.pos * 100;
		let second_CSS_gradient_stop = first_CSS_gradient_stop - 1  + "%";
		first_CSS_gradient_stop = first_CSS_gradient_stop + "%";
		let media_url_str = "url(https://" + infos_array_element.host + ":" + CMD_PORT + "/thumb/" + infos_array_element.file + ")";
		let media_cssgrad_rule = "linear-gradient(90deg," + TIMELINE_COLOR_BG + " " + second_CSS_gradient_stop + ", " + TIMELINE_COLOR_CURSOR + " " + first_CSS_gradient_stop + ", " + TIMELINE_COLOR_BG + " " + first_CSS_gradient_stop + ")," + media_url_str;
		media_element.style.backgroundImage = media_cssgrad_rule;
		media_element.style.borderBottom = "4px solid " + TIMELINE_COLOR_CURSOR;
	    } else {
		let media_url_str = "url(https://" + infos_array_element.host + ":" + CMD_PORT + "/thumb/" + media_element.innerText + ")"
		media_element.style.backgroundImage = media_url_str;
		media_element.style.borderBottom = "None";
	    }
	});
    } else {
	document.getElementById("status_" + infos_array_element.host).innerHTML = "<br><br>";
    }
    toggle_indicator(infos_array_element, "loop");
    toggle_indicator(infos_array_element, "repeat");
    return infos_array_element.status;
}


function update_list(infos_array_element){
    // Playlist infos are displayed in a div ; number of items in list and total duration.
    //~ document.getElementById("playlist_"+infos_array[i].host).innerHTML = infos_array[i].leng + " item(s) in playlist - " + infos_array[i].duration;
    // Populate timeline according to the content of the playlist
    // Get returned items as an array
    let items_array = Array.from(infos_array_element.items);
    let host = infos_array_element.host;
    // If playlist is empty, remove all media divs in the timeline UI.
    if (items_array.length == 0){
	let child_list = Array.from(document.getElementById("timeline_" + host).children);
	child_list.forEach(function(child){
	    document.getElementById("timeline_" + host).removeChild(child);
	});
    } else {
	items_array.forEach(function(item, j){
	    item_meta = item.split(';');
	    let child_node = add_HTML_element("div", tl_drag_attr, item_meta, j);
	    let len = document.getElementById("timeline_" + host).children.length;
	    add_HTML_attr("timeline_" + host, "length", len);
	    if ( len < items_array.length ) {
		document.getElementById("timeline_" + host).appendChild( add_HTML_element("div", tl_cont_attr, 0, len) );
	    } 
	    document.getElementById(tl_cont_attr.id + j).replaceChildren(child_node);
	    let media_name = document.getElementById(tl_cont_attr.id + j).children[0].innerText;
	    let media_url_str = "url(https://" + host + ":" + CMD_PORT + "/thumb/" + media_name + ")"
	    document.getElementById(tl_cont_attr.id + j).children[0].style.backgroundImage = media_url_str;
	    // Adjust elements width
	    adjust_timeline();
	});
    }
    return items_array.length;
}


function populate_HTML_table(inner_text, host="all", CSS_class="file_selection") {
    tr = document.createElement("tr");
    td = document.createElement("td");
    tr.appendChild(td);
    tr.setAttribute("class", CSS_class);
    tr.host = host;
    td.innerText = inner_text;
    // Add an event to the created element to send enqueue command when a file is clicked in the list
    tr.addEventListener("click", enqueue_file, false);
    document.getElementById("file_sel_" + host).appendChild(tr);
}

function update_remote_filelist(infos_array_element) {
    hosts = Object.keys(infos_array_element);
    for (let j=0, m=hosts.length; j<m; j++) {
	let media_item = Object.keys(infos_array_element[hosts[j]]);
	for (let k=0, n=media_item.length; k<n; k++) {
	    media_item_meta = infos_array_element[hosts[j]][media_item[k]];
	    populate_HTML_table(media_item_meta.name, hosts[j]);
	}
    }
}


function update_rssi_indicator(infos_array_element){
    let signal_color = 40;
    let best_rssi = 30;
    let worst_rssi = 70;
    let rssi_norm = Math.ceil( (worst_rssi - parseInt(infos_array_element.rssi) ) / ( worst_rssi - best_rssi ) * 4 );
    signal_color = (rssi_norm-1) * signal_color;
    // Reset to grey
    for (let i=0, l=4; i<l; i++) {
	document.getElementById("wl_"+i).style.backgroundColor = "hsl(0, 0%, 65%)";
    }
    // Color it
    for (let i=0, l=rssi_norm > 4 ? 4 : rssi_norm; i<l; i++) {
	document.getElementById("wl_"+i).style.backgroundColor = "hsl(" + signal_color + ", 100%, 50%)";
    }
    return rssi_norm;
}


function update_local_filelist(infos_array) {
    // TODO : Is this useful ?
    // TODO : Get real media length
    let html_table  = "<table>" + 
		       "<tr>" + 
			    "<th>Filename</th>" + 
			    "<th>Duration</th>" + 
		       "</tr>";
    infos_array.forEach(function(element){
	html_table += "<tr>" + 
			    "<td>" + element + "</td>" +
			    "<td>" + "00:00" + "</td>" +
		      "</tr>" ;
    });
    html_table += "</table>";
    return html_table;
}


function update_host_list(infos_array){
    let host_up = infos_array[0];
    let host_down = infos_array[1];
    if (host_up.length) { 
	host_up.forEach(function(host){
	    document.getElementById(host).style.display = 'block';
	    send_ajax_cmd("/" + host + "/list");
	    send_ajax_cmd("/" + host + "/rssi");
	});
	currentUser.scan_interval = 10000;
    }
    host_down.forEach(function(element){
	document.getElementById(element).style.display = 'none';
    });
    currentUser.status_all = host_up.length + " client(s).";
    return host_up.length;
}


// Metadata display
function parse_result(command, infos_array) {
	if (command == "/all/status") {
	    // Requests current status of every instances, especially current media file's name, position and length. 
	    // Also retrieves loop and repeat status.
	    infos_array.forEach(update_status);
	    
	} else if ( command.indexOf("/list") > -1 ) {
	    // Requests playlist of every instances
	    if (!currentUser.freeze_timeline_update){
		infos_array.forEach(update_list);
	    }
	    
	} else if ( command == "/scan") {
	    // Scan for live hosts
	    update_host_list(infos_array);
	    
	} else if ( command == "/browse_local") {
	    // Display local media files in a table
	    document.getElementById("filelist").innerHTML = update_local_filelist(infos_array);
	    
	} else if ( command == "/all/rssi") {
	    // RSSI strength indicator
	    infos_array.forEach(update_rssi_indicator);
	    
	} else if ( command == "/all/browse") {
	    // Display remote media files in a table
	    infos_array.forEach(update_remote_filelist);
	    
	} else if ( command == "/sync/status") {
	    // TODO : File sync UI status
	    currentUser.status_all = infos_array;
	    
	} else  {
	    setTimeout(send_ajax_cmd, 80, "/all/list");
	    setTimeout(send_ajax_cmd, 120, "/all/status");
	}
}


function send_ajax_cmd(command) {
    let request = new XMLHttpRequest();
    request.onload = function() {
	if (request.readyState === request.DONE) {
	    if (request.status === 200) {
	    // responseText is a string, use parse to get an array.
		if (!currentUser.freeze_timeline_update) {
		    let infos_array = JSON.parse(request.responseText);  
		    parse_result(command, infos_array);
		}
	    }
	}
    };
    request.open("GET", command, true);
    request.send();     
}


function enqueue_file(evt) {
    send_ajax_cmd("/" + evt.currentTarget.host + "/enqueue/" + evt.currentTarget.innerText);
    setTimeout(send_ajax_cmd, 40, "/" + evt.currentTarget.host + "/list");
}


function update_statusall_content() {
    document.getElementById("status_all").innerHTML = currentUser.status_all;
}


function scan_hosts() {
    send_ajax_cmd("/scan");
    update_statusall_content();
    setTimeout(scan_hosts, currentUser.scan_interval);
};


// UI 
addEventListener("DOMContentLoaded", function() {
    adjust_timeline();
    let commandButtons = document.querySelectorAll(".command");
    for (let i=0, l=commandButtons.length; i<l; i++) {
	let button = commandButtons[i];
	button.addEventListener("click", function(event) {
	    event.preventDefault();
	    let clickedButton = event.currentTarget;
	    let command = clickedButton.value;
	    
	    if ( command.indexOf("/reboot" ) > -1  ||  command.indexOf("/poweroff") > -1 ) {
		// TODO : l10n
		if ( !confirm("Êtes vous certain de vouloir effectuer cette action ?") ) {
		    return 0;
		}

	    } else if ( command == "/scan" ) {
		document.getElementById("status_all").innerHTML = currentUser.status_all;
		
	    } else if ( command.indexOf("/sort") > -1 ){ 
		if (command.indexOf('/1/') > -1 ) {
		    clickedButton.value = clickedButton.value.replace('/1/','/0/');
		    
		} else {
		    clickedButton.value = clickedButton.value.replace('/0/','/1/');
		}
	    }

	    // AJAX request
	    let request = new XMLHttpRequest();
	    if ( command == "/scan") {
		request.onload = send_ajax_cmd(command);
		
	    } else if ( command.indexOf("/clear") > -1 || command.indexOf("/sort") > -1) {
		request.onload = send_ajax_cmd(command);
		
	    } else if ( command == "/sync/all" ) {
		currentUser.status_all = "Syncing files...";
		request.onload = send_ajax_cmd("/sync/status");
		
	    }

	    request.open("GET", command, true);
	    request.send();
	});
    }
}, true);

send_ajax_cmd("/scan");
send_ajax_cmd("/browse_local");
setInterval(send_ajax_cmd, 500, "/all/status");
setTimeout(send_ajax_cmd, 1000, "/all/list");
setTimeout(send_ajax_cmd, 3000, "/all/browse");
setInterval(send_ajax_cmd, 20000, "/all/rssi");
setTimeout(scan_hosts, currentUser.scan_interval);