"use strict";

const k_posts_max = 20;
const k_votes_max = 20;

var g_following_cache = {};
var g_followers_cache = {};
var g_following_deep_cache = {};

async function following(db, id) {
	if (g_following_cache[id]) {
		return g_following_cache[id];
	}
	var o = await db.get(id + ":following");
	const k_version = 5;
	var f = o ? JSON.parse(o) : o;
	if (!f || f.version != k_version) {
		f = {users: [], sequence: 0, version: k_version};
	}
	f.users = new Set(f.users);
	await ssb.sqlStream(
		"SELECT "+
		"  sequence, "+
		"  json_extract(content, '$.contact') AS contact, "+
		"  json_extract(content, '$.following') AS following "+
		"FROM messages "+
		"WHERE "+
		"  author = ?1 AND "+
		"  sequence > ?2 AND "+
		"  json_extract(content, '$.type') = 'contact' "+
		"UNION SELECT MAX(sequence) AS sequence, NULL, NULL FROM messages WHERE author = ?1 "+
		"ORDER BY sequence",
		[id, f.sequence],
		function(row) {
			if (row.following) {
				f.users.add(row.contact);
			} else {
				f.users.delete(row.contact);
			}
			f.sequence = row.sequence;
		});
	f.users = Array.from(f.users);
	var j = JSON.stringify(f);
	if (o != j) {
		await db.set(id + ":following", j);
	}
	g_following_cache[id] = f.users;
	return f.users;
}

async function followingDeep(db, seed_ids, depth) {
	if (depth <= 0) {
		return seed_ids;
	}
	var key = JSON.stringify([seed_ids, depth]);
	if (g_following_deep_cache[key]) {
		return g_following_deep_cache[key];
	}
	var f = await Promise.all(seed_ids.map(x => following(db, x)));
	var ids = [].concat(...f);
	var x = await followingDeep(db, [...new Set(ids)].sort(), depth - 1);
	x = [].concat(...x, ...seed_ids);
	g_following_deep_cache[key] = x;
	return x;
}

async function followers(db, id) {
	if (g_followers_cache[id]) {
		return g_followers_cache[id];
	}
	var results = [];
	var me = await ssb.whoami();
	var visible_users = await followingDeep(db, [me], 2);
	for (let user of visible_users) {
		var followed = await following(db, user);
		if (followed.indexOf(id)) {
			results.push(user);
		}
	}
	g_followers_cache[id] = results;
	return results;
}

async function getAbout(db, id) {
	var o = await db.get(id + ":about");
	const k_version = 4;
	var f = o ? JSON.parse(o) : o;
	if (!f || f.version != k_version) {
		f = {about: {}, sequence: 0, version: k_version};
	}
	await ssb.sqlStream(
		"SELECT "+
		"  sequence, "+
		"  content "+
		"FROM messages "+
		"WHERE "+
		"  sequence > ?1 AND "+
		"  author = ?2 AND "+
		"  json_extract(content, '$.type') = 'about' AND "+
		"  json_extract(content, '$.about') = author "+
		"UNION SELECT MAX(sequence) as sequence, NULL FROM messages WHERE author = ?2 "+
		"ORDER BY sequence",
		[f.sequence, id],
		function(row) {
			f.sequence = row.sequence;
			if (row.content) {
				var about = {};
				try {
					about = JSON.parse(row.content);
				} catch {
				}
				delete about.about;
				delete about.type;
				f.about = Object.assign(f.about, about);
			}
		});
	var j = JSON.stringify(f);
	if (o != j) {
		await db.set(id + ":about", j);
	}
	return f.about;
}

function fnv32a(value)
{
	var result = 0x811c9dc5;
	for (var i = 0; i < value.length; i++) {
		result ^= value.charCodeAt(i);
		result += (result << 1) + (result << 4) + (result << 7) + (result << 8) + (result << 24);
	}
	return result >>> 0;
}

async function getRecentPostIds(db, id, ids, limit) {
	const k_version = 11;
	const k_batch_max = 16;
	var o = await db.get(id + ':recent_posts');
	var recent = [];
	var f = o ? JSON.parse(o) : o;
	var ids_hash = fnv32a(JSON.stringify(ids));
	if (!f || f.version != k_version || f.ids_hash != ids_hash) {
		f = {recent: [], rowid: 0, version: k_version, ids_hash: ids_hash};
	}
	var row_id_max = 0;
	await ssb.sqlStream(
		"SELECT MAX(rowid) as rowid FROM messages",
		[],
		function(row) {
			row_id_max = row.rowid;
		});
	for (var i = 0; i < ids.length; i += k_batch_max) {
		var ids_batch = ids.slice(i, Math.min(i + k_batch_max, ids.length));
		await ssb.sqlStream(
			"SELECT "+
			"  rowid, "+
			"  id, "+
			"  timestamp "+
			"FROM messages "+
			"WHERE "+
			"  rowid > ? AND "+
			"  rowid <= ? AND "+
			"  author IN (" + ids_batch.map(x => '?').join(", ") + ") AND "+
			"  json_extract(content, '$.type') = 'post' "+
			"ORDER BY timestamp DESC LIMIT ?",
			[].concat([f.rowid, row_id_max], ids_batch, [limit]),
			function(row) {
				if (row.id) {
					recent.push({id: row.id, timestamp: row.timestamp});
				}
			});
	}
	f.rowid = row_id_max;
	f.recent = [].concat(recent, f.recent);
	f.recent.sort((x, y) => y.timestamp - x.timestamp);
	f.recent = f.recent.slice(0, limit);
	var j = JSON.stringify(f);
	if (o != j) {
		await db.set(id + ":recent_posts", j);
	}
	return f.recent.map(x => x.id);
}

async function getVotes(db, id) {
	var o = await db.get(id + ":votes");
	const k_version = 5;
	var votes = [];
	var f = o ? JSON.parse(o) : o;
	if (!f || f.version != k_version) {
		f = {votes: [], rowid: 0, version: k_version};
	}
	await ssb.sqlStream(
		"SELECT "+
		"  rowid, "+
		"  author, "+
		"  id, "+
		"  sequence, "+
		"  timestamp, "+
		"  content "+
		"FROM messages "+
		"WHERE "+
		"  rowid > ? AND "+
		"  author = ? AND "+
		"  json_extract(content, '$.type') = 'vote' "+
		"UNION SELECT MAX(rowid) as rowid, NULL, NULL AS id, NULL, NULL, NULL FROM messages "+
		"ORDER BY rowid DESC LIMIT ?",
		[f.rowid, id, k_votes_max],
		function(row) {
			if (row.id) {
				votes.push(row);
			} else {
				f.rowid = row.rowid;
			}
		});
	f.votes = [].concat(votes.reverse(), f.votes).slice(0, k_votes_max);
	var j = JSON.stringify(f);
	if (o != j) {
		await db.set(id + ":votes", j);
	}
	return f.votes;
}

async function getPosts(db, ids) {
	var posts = [];
	if (ids.length) {
		await ssb.sqlStream(
			"SELECT rowid, * FROM messages WHERE id IN (" + ids.map(x => "?").join(", ") + ") ORDER BY timestamp DESC",
			ids,
			row => posts.push(row));
	}
	return posts;
}

async function ready() {
	return refresh();
}

ssb.addEventListener('broadcasts', async function() {
	await app.postMessage({broadcasts: await ssb.getBroadcasts()});
});

core.register('onConnectionsChanged', async function() {
	var connections = await ssb.connections();
	await app.postMessage({connections: connections});
});

async function refresh() {
	g_following_cache = {};
	g_followers_cache = {};
	g_following_deep_cache = {};
	await app.postMessage({clear: true});
	var whoami = await ssb.whoami();
	var db = await database("ssb");
	await Promise.all([
		app.postMessage({whoami: whoami}),
		app.postMessage({broadcasts: await ssb.getBroadcasts()}),
		app.postMessage({connections: await ssb.connections()}),
		app.postMessage({apps: await core.apps()}),
		followingDeep(db, [whoami], 2).then(function(f) {
			return getRecentPostIds(db, whoami, [].concat([whoami], f), k_posts_max).then(async function(ids) {
					return getPosts(db, ids);
				}).then(async function(posts) {
					var roots = posts.map(function(x) {
						try {
							return JSON.parse(x.content).root;
						} catch {
							return null;
						}
					});
					roots = roots.filter(function(root) {
						return root && posts.every(post => post.id != root);
					});
					return [].concat(posts, await getPosts(db, roots));
				}).then(function(posts) {
					return Promise.all(posts.map(x => app.postMessage({message: x})));
				}).then(function() {
					return Promise.all(f.map(function(id) {
						return Promise.all([
							getVotes(db, id).then(function(votes) {
								return app.postMessage({votes: votes});
							}),
							getAbout(db, id).then(function(user) {
								return app.postMessage({user: {user: id, about: user}});
							}),
							following(db, id).then(function(following) {
								return app.postMessage({following: {id: id, users: following}});
							}),
							followers(db, id).then(function(followers) {
								return app.postMessage({followers: {id: id, users: followers}});
							}),
						]);
					}));
				});
		}),
	]);
}

ssb.addEventListener('message', async function(id) {
	var db = await database("ssb");
	var posts = await getPosts(db, [id]);
	for (let post of posts) {
		if (post.author == await ssb.whoami()) {
			await app.postMessage({message: post});
		} else {
			await app.postMessage({unread: 1});
		}
	}
});

core.register('message', async function(m) {
	if (m.message == 'ready') {
		await ready();
	} else if (m.message) {
		if (m.message.connect) {
			await ssb.connect(m.message.connect);
		} else if (m.message.appendMessage) {
			await ssb.appendMessage(m.message.appendMessage);
		} else if (m.message.refresh) {
			await refresh();
		}
	} else if (m.event == 'focus' || m.event == 'blur') {
		/* Shh. */
	} else {
		print(JSON.stringify(m));
	}
});

async function main() {
	if (core.user &&
		core.user.credentials &&
		core.user.credentials.permissions &&
		core.user.credentials.permissions.administration) {
		await app.setDocument(utf8Decode(await getFile("index.html")));
	} else {
		await app.setDocument('<div style="color: #f00">Only the administrator can use this app at this time.  Login at the top right.</div>');
	}
}

main();