From 2d7b011bba916290fa8e7b5bf30b4750af89d437 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Sun, 3 Jun 2018 18:43:17 -0700
Subject: [PATCH] ircd::m::v1: Add frontfill request.

---
 include/ircd/m/v1/frontfill.h |  50 ++++++++++++++++
 include/ircd/m/v1/v1.h        |   1 +
 ircd/m/v1.cc                  | 105 ++++++++++++++++++++++++++++++++++
 3 files changed, 156 insertions(+)
 create mode 100644 include/ircd/m/v1/frontfill.h

diff --git a/include/ircd/m/v1/frontfill.h b/include/ircd/m/v1/frontfill.h
new file mode 100644
index 000000000..dbba1b285
--- /dev/null
+++ b/include/ircd/m/v1/frontfill.h
@@ -0,0 +1,50 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_M_V1_FRONTFILL_H
+
+namespace ircd::m::v1
+{
+	struct frontfill;
+};
+
+struct ircd::m::v1::frontfill
+:server::request
+{
+	struct opts;
+	using span = std::pair<m::event::id, m::event::id>;
+	using vector = vector_view<const m::event::id>;
+	using ranges = std::pair<vector, vector>;
+
+    static const_buffer make_content(const mutable_buffer &, const ranges &, const opts &);
+
+	explicit operator json::array() const
+	{
+		const json::object content{in.content};
+		return content.get("events");
+	}
+
+	frontfill(const room::id &, const ranges &, const mutable_buffer &, opts);
+	frontfill(const room::id &, const span &, const mutable_buffer &, opts);
+	frontfill() = default;
+};
+
+struct ircd::m::v1::frontfill::opts
+{
+	net::hostport remote;
+	size_t limit {64};
+	uint64_t min_depth {0};
+	m::request request;
+	server::out out;
+	server::in in;
+	const struct server::request::opts *sopts {nullptr};
+	bool dynamic {true};
+};
diff --git a/include/ircd/m/v1/v1.h b/include/ircd/m/v1/v1.h
index e3ff7b4c5..a02d924f4 100644
--- a/include/ircd/m/v1/v1.h
+++ b/include/ircd/m/v1/v1.h
@@ -28,6 +28,7 @@ namespace ircd::m::v1
 #include "event_auth.h"
 #include "state.h"
 #include "backfill.h"
+#include "frontfill.h"
 #include "public_rooms.h"
 #include "send.h"
 #include "groups.h"
diff --git a/ircd/m/v1.cc b/ircd/m/v1.cc
index be970b16b..9433a9abc 100644
--- a/ircd/m/v1.cc
+++ b/ircd/m/v1.cc
@@ -213,6 +213,111 @@ ircd::m::v1::public_rooms::public_rooms(const net::hostport &remote,
 {
 }
 
+///////////////////////////////////////////////////////////////////////////////
+//
+// v1/frontfill.h
+//
+
+ircd::m::v1::frontfill::frontfill(const room::id &room_id,
+                                  const span &span,
+                                  const mutable_buffer &buf,
+                                  opts opts)
+:frontfill
+{
+	room_id,
+	ranges { vector(&span.first, 1), vector(&span.second, 1) },
+	buf,
+	std::move(opts)
+}
+{
+}
+
+ircd::m::v1::frontfill::frontfill(const room::id &room_id,
+                                  const ranges &pair,
+                                  const mutable_buffer &buf_,
+                                  opts opts)
+:server::request{[&]
+{
+	assert(!!opts.remote);
+
+	if(!defined(json::get<"origin"_>(opts.request)))
+		json::get<"origin"_>(opts.request) = my_host();
+
+	if(!defined(json::get<"destination"_>(opts.request)))
+		json::get<"destination"_>(opts.request) = host(opts.remote);
+
+	if(defined(json::get<"content"_>(opts.request)))
+		opts.out.content = json::get<"content"_>(opts.request);
+
+	if(!defined(json::get<"uri"_>(opts.request)))
+	{
+		thread_local char urlbuf[1024], ridbuf[768];
+		json::get<"uri"_>(opts.request) = fmt::sprintf
+		{
+			urlbuf, "/_matrix/federation/v1/get_missing_events/%s/",
+			url::encode(room_id, ridbuf)
+		};
+	}
+
+	window_buffer buf{buf_};
+	if(!defined(json::get<"content"_>(opts.request)))
+	{
+		buf([&pair, &opts](const mutable_buffer &buf)
+		{
+			return make_content(buf, pair, opts);
+		});
+
+		json::get<"content"_>(opts.request) = json::object{buf.completed()};
+		opts.out.content = json::get<"content"_>(opts.request);
+	}
+
+	json::get<"method"_>(opts.request) = "POST";
+	opts.out.head = opts.request(buf);
+
+	if(!size(opts.in))
+	{
+		opts.in.head = buf + size(opts.out.head);
+		opts.in.content = opts.dynamic?
+			mutable_buffer{}:  // server::request will allocate new mem
+			opts.in.head;      // server::request will auto partition
+	}
+
+	return server::request
+	{
+		opts.remote, std::move(opts.out), std::move(opts.in), opts.sopts
+	};
+}()}
+{
+}
+
+ircd::const_buffer
+ircd::m::v1::frontfill::make_content(const mutable_buffer &buf,
+	                                 const ranges &pair,
+	                                 const opts &opts)
+{
+	json::stack out{buf};
+	{
+		// note: This object must be in abc order
+		json::stack::object top{out};
+		{
+			json::stack::member earliest{top, "earliest_events"};
+			json::stack::array array{earliest};
+			for(const auto &id : pair.first)
+				array.append(id);
+		}
+		{
+			json::stack::member latest{top, "latest_events"};
+			json::stack::array array{latest};
+			for(const auto &id : pair.second)
+				array.append(id);
+		}
+		json::stack::member{top, "limit", json::value(int64_t(opts.limit))};
+		json::stack::member{top, "min_depth", json::value(int64_t(opts.min_depth))};
+	}
+
+	return out.completed();
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 //
 // v1/backfill.h