<script>
import { createEventDispatcher } from "svelte";
let dispatch = createEventDispatcher();

export let bucket_id;
export let target_dir;

let upload_jobs = [];
let upload_threads = 0;
let max_upload_threads = 3;

// Adds files to the upload queue. The file_list parameter needs to be of type
// FileList. Upload will also create the necessary directories to place nested
// files in.
export const upload = (file_list) => {
	console.log(file_list)

	for (let i = 0; i < file_list.length; i++) {
		upload_jobs.push({
			file: file_list[i],
			progress: 0,
			target_dir: target_dir.valueOf(),
			uploading: false,
			finished: false,
			tries: 0,
		});
	}

	// This updates the UI
	upload_jobs = upload_jobs;

	while (upload_threads < max_upload_threads) {
		upload_threads++;
		setTimeout(upload_file, 1);
	}
};

const uploads_finished = () => {
	dispatch("finished");
};

const upload_file = () => {
	let job = null;
	for (let i = 0; i < upload_jobs.length; i++) {
		// If a file is done we remove it from the array
		if (upload_jobs[i].progress >= 1) {
			upload_jobs.splice(i, 1);
			continue;
		}

		if (
			upload_jobs[i].uploading === false &&
			upload_jobs[i].finished === false
		) {
			job = upload_jobs[i];
			job.uploading = true;
			upload_jobs = upload_jobs;
			break;
		}
	}
	if (job === null) {
		upload_threads--;

		if (upload_threads === 0) {
			uploads_finished();
		}
		return;
	}

	console.log(job);

	let form = new FormData();
	form.append("type", "file");
	form.append("file", job.file);

	let xhr = new XMLHttpRequest();
	xhr.open(
		"POST",
		"/api/filesystem/" +
			bucket_id +
			encodeURIComponent(job.target_dir + "/" + job.file.name),
		true
	);
	xhr.timeout = 21600000; // 6 hours, to account for slow connections

	// Report progress updates back to the caller
	xhr.upload.addEventListener("progress", (evt) => {
		if (evt.lengthComputable) {
			job.progress = evt.loaded / evt.total;
			upload_jobs = upload_jobs;
		}
	});

	xhr.onreadystatechange = () => {
		// readystate 4 means the upload is done
		if (xhr.readyState !== 4) {
			return;
		}

		if (xhr.status >= 100 && xhr.status < 400) {
			// Request is a success

			// Finish the upload job
			job.uploading = false;
			job.finished = true;
			upload_file();
		} else if (xhr.status >= 400) {
			// Request failed
			console.log(
				"Upload error. status: " +
					xhr.status +
					" response: " +
					xhr.response
			);
			let resp = JSON.parse(xhr.response);
			if (job.tries === 3) {
				// Upload failed
				return;
			} else {
				// Try again
				job.tries++;
				job.uploading = false;
				job.finished = false;
			}

			// Sleep the upload thread for 5 seconds
			setTimeout(upload_file, 5000);
		} else {
			// Request did not arrive
			if (job.tries === 3) {
				// Upload failed
				alert("upload failed " + xhr.responseText);
				job.uploading = false;
				job.finished = false;
			} else {
				// Try again
				job.tries++;
			}

			// Sleep the upload thread for 5 seconds
			setTimeout(upload_file, 5000);
		}

		upload_jobs = upload_jobs;
	};
	xhr.send(form);
};

// File input dialog handling
let file_input;
export const picker = () => {
	file_input.click();
};
const file_input_change = (e) => {
	upload(e.target.files);
	file_input.nodeValue = "";
};

// Drag and drop upload
let hidden = true;
const dragover = (e) => {
	hidden = false;
};
const dragleave = (e) => {
	hidden = true;
};
const drop = (e) => {
	hidden = true;
	upload(e.dataTransfer.files);
};
const paste = (e) => {
	if (e.clipboardData.files[0]) {
		e.preventDefault();
		e.stopPropagation();
		console.log(e.clipboardData.files[0]);
		upload(e.clipboardData.files)
	}
};
</script>

<style>
	.hidden {
		display: none;
	}

	.file_input {
		display: block;
		visibility: hidden;
		width: 0;
		height: 0;
	}

	.file_upload {
		display: block;
		text-align: left;
		width: 100%;
		margin: 6px 0 0 0;
		padding: 0;
		background-color: var(--layer_2_color);
		box-shadow: 1px 1px 5px var(--shadow_color);
	}

	.upload_progress_bar {
		width: 100%;
		height: 2px;
	}
	.upload_progress {
		background-color: var(--highlight_color);
		height: 100%;
	}
</style>

<svelte:body
	on:dragover|preventDefault|stopPropagation={dragover}
	on:dragleave|preventDefault|stopPropagation={dragleave}
	on:drop|preventDefault|stopPropagation={drop}
	on:paste={paste} />

<div>
	<input
		class="file_input"
		bind:this={file_input}
		on:change={file_input_change}
		type="file"
		multiple="multiple" />
	<div class:hidden class="highlight_green">
		Drop files here to upload them
	</div>

	{#each upload_jobs as c}
		<div class="file_upload">
			&nbsp;{c.file.name}&nbsp;<br />
			<div class="upload_progress_bar">
				<div
					class="upload_progress"
					style="width: {c.progress * 100}%" />
			</div>
		</div>
	{/each}
</div>
