// Copyright Epic Games, Inc. All Rights Reserved.

"use strict";

import { Fetcher } from "../util/fetcher.js"

////////////////////////////////////////////////////////////////////////////////
export class Message
{
	static None		= 0;	//
	static Init		= 1;	// project_id, oplog
	static Map		= 2;	// start, end, page_size, stride
	static MapPage	= 3;	// page
	static MapDone	= 4;	//

	static create(msg, ...args) { return [msg, ...args]; }
}



////////////////////////////////////////////////////////////////////////////////
async function map_id_to_key(project_id, oplog, start, end, page_size, stride)
{
	if (start >= end)
		return postMessage(Message.create(Message.MapDone));

	const uri = "/prj/" + project_id + "/oplog/" + oplog + "/entries";

	const fetch_page = async function(index) {
		const cbo = new Fetcher()
			.resource(uri)
			.param("start", index)
			.param("count", page_size)
			.param("fieldfilter", "packagedata,bulkdata,key")
			.cbo()

		const entry_count = Math.min(page_size, -(index - end));
		return [await cbo, entry_count];
	};

	var fetch = fetch_page(start);
	while (fetch !== undefined)
	{
		performance.mark("fetch");

		const [cbo, entry_count] = await fetch;
		start += stride;
		fetch = (start < end) ? fetch_page(start) : undefined;

		var entries = (await cbo).as_object().find("entries");
		if (entries == undefined)
			break;

		entries = entries.as_array();
		if (entries.num() == 0)
			break;

		performance.mark("build");
		var count = 0;
		var result = new Array(entry_count);
		for (var entry of entries)
		{
			if (!entry.is_object())
				continue
			entry = entry.as_object();

			var key = undefined;
			var pkg_data = undefined;
			var bulk_data = undefined;
			for (const field of entry)
			{
				if (field.is_named("key"))				key = field;
				else if (field.is_named("packagedata")) pkg_data = field;
				else if (field.is_named("bulkdata"))	bulk_data = field;
			}

			if (key == undefined)
				continue;

			var id = 0n;
			var size = 0n;
			var raw_size = 0n;

			if (pkg_data)
			{ 
				for (const item of pkg_data.as_array())
				{
					var found = 0, pkg_id = undefined;
					for (const field of item.as_object())
					{
						if (!id && field.is_named("id"))	pkg_id = field.as_value();
						else if (field.is_named("size"))	size += field.as_value();
						else if (field.is_named("rawsize"))	raw_size += field.as_value();
						else continue;
						if (found++ >= 3)
							break;
					}

					if (pkg_id === undefined)
						continue;

					pkg_id = pkg_id.subarray(0, 8);
					for (var i = 7; i >= 0; --i)
					{
						id <<= 8n;
						id  |= BigInt(pkg_id[i]);
					}
				}
			}

			if (bulk_data)
			{
				for (const item of bulk_data.as_array())
				{
					var found = 0;
					for (const field of item.as_object())
					{
						if (field.is_named("size"))			size += field.as_value();
						else if (field.is_named("rawsize"))	raw_size += field.as_value();
						else continue;
						if (found++ >= 2)
							break;
					}
				}
			}

			result[count] = [id, key.as_value(), size, raw_size];
			count++;
		}

		if (count == 0)
			continue;

		if (count != result.length)
			result = result.slice(0, count);

		performance.mark("sort");
		result.sort(function(l, r) { return Number(l[0] - r[0]); });

		const msg = Message.create(Message.MapPage, result);
		postMessage(msg);
	}

	postMessage(Message.create(Message.MapDone));
}

////////////////////////////////////////////////////////////////////////////////
function worker_scope()
{
	var project_id;
	var oplog;

	return (evt) => {
		const [msg_id, ...params] = evt.data;
		switch (msg_id)
		{
		case Message.Init:
			[project_id, oplog] = params;
			break;

		case Message.Map:
			var [start, end, page_size, stride] = params;
			map_id_to_key(project_id, oplog, start, end, page_size, stride);
			break;
		}
	}
}

////////////////////////////////////////////////////////////////////////////////
if (typeof DedicatedWorkerGlobalScope != "undefined" && self instanceof DedicatedWorkerGlobalScope)
{
	onmessage = worker_scope();
}