"use strict";

const k_posts_max = 20;
const k_votes_max = 20;

async function following(db, 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);
	}
	return f.users;
}

async function followingDeep(db, seed_ids, depth) {
	if (depth <= 0) {
		return seed_ids;
	}
	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);
	return x;
}

async function followers(db, id) {
	var o = await db.get(id + ":followers");
	const k_version = 3;
	var f = o ? JSON.parse(o) : o;
	if (!f || f.version != k_version) {
		f = {users: [], rowid: 0, version: k_version};
	}
	f.users = new Set(f.users);
	await ssb.sqlStream(
		"SELECT "+
		"  rowid, "+
		"  author AS contact, "+
		"  json_extract(content, '$.following') AS following "+
		"FROM messages "+
		"WHERE "+
		"  rowid > $1 AND "+
		"  json_extract(content, '$.type') = 'contact' AND "+
		"  json_extract(content, '$.contact') = $2 "+
		"UNION SELECT MAX(rowid) as rowid, NULL, NULL FROM messages "+
		"ORDER BY rowid",
		[f.rowid, id],
		function(row) {
			if (row.following) {
				f.users.add(row.contact);
			} else {
				f.users.delete(row.contact);
			}
			f.rowid = row.rowid;
		});
	f.users = Array.from(f.users);
	var j = JSON.stringify(f);
	if (o != j) {
		await db.set(id + ":followers", j);
	}
	return f.users;
}

async function sendUser(db, id) {
	return Promise.all([
		following(db, id).then(async function(following) {
			return app.postMessage({following: {id: id, users: following}});
		}),
		followers(db, id).then(async function(followers) {
			return app.postMessage({followers: {id: id, users: followers}});
		}),
	]);
}

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 = 9;
	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};
	}
	await ssb.sqlStream(
		"SELECT "+
		"  rowid, "+
		"  id, "+
		"  timestamp "+
		"FROM messages "+
		"WHERE "+
		"  rowid > ? AND "+
		"  author IN (" + ids.map(x => '?').join(", ") + ") AND "+
		"  json_extract(content, '$.type') IN ('post', 'tildefriends-app') "+
		"UNION SELECT MAX(rowid) as rowid, NULL, NULL FROM messages "+
		"ORDER BY timestamp DESC LIMIT ?",
		[].concat([f.rowid], ids, [limit + 1]),
		function(row) {
			if (row.id) {
				recent.push(row.id);
			}
			if (row.rowid) {
				f.rowid = row.rowid;
			}
		});
	f.recent = [].concat(recent, f.recent).slice(0, limit);
	var j = JSON.stringify(f);
	if (o != j) {
		await db.set(id + ":recent_posts", j);
	}
	return f.recent;
}

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() {
	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) {
			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})));
			});
			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}});
					}),
				]);
			}));
		}),
		sendUser(db, whoami),
	]);
}

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

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.post) {
			await ssb.post(m.message.post);
		} else if (m.message.appendMessage) {
			await ssb.appendMessage(m.message.appendMessage);
		} else if (m.message.share_app) {
			var app = await ssb.blobGet(m.message.share_app.app);
			app = JSON.parse(utf8Decode(app));
			app.type = 'tildefriends-app';
			app.name = m.message.share_app.name;
			app.text = m.message.share_app.text;
			await ssb.appendMessage(app);
		} else if (m.message.user) {
			await sendUser(await database("ssb"), m.message.user);
		} 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();