proxy_cache_path /data/nginx/cache levels=1:2 keys_zone=skynet:10m max_size=10g inactive=24h use_temp_path=off;

# ratelimit specified IPs
geo $limit {
	default 0;
	include /etc/nginx/conf.d/include/ratelimited;
}
map $limit $limit_key {
	0 "";
	1 $binary_remote_addr;
}

limit_req_zone $binary_remote_addr zone=uploads_by_ip:10m rate=10r/s;
limit_req_zone $limit_key zone=uploads_by_ip_throttled:10m rate=10r/m;

limit_req_zone $binary_remote_addr zone=registry_access_by_ip:10m rate=60r/m;
limit_req_zone $limit_key zone=registry_access_by_ip_throttled:10m rate=20r/m;

limit_conn_zone $binary_remote_addr zone=upload_conn:10m;
limit_conn_zone $limit_key zone=upload_conn_rl:10m;

limit_conn_zone $binary_remote_addr zone=downloads_by_ip:10m;

limit_req_status 429;
limit_conn_status 429;

# since we are proxying request to nginx from caddy, access logs will contain caddy's ip address 
# as the request address so we need to use real_ip_header module to use ip address from 
# X-Forwarded-For header as a real ip address of the request
set_real_ip_from  10.0.0.0/8;
set_real_ip_from  127.0.0.1/32;
set_real_ip_from  172.16.0.0/12;
set_real_ip_from  192.168.0.0/16;
real_ip_header    X-Forwarded-For;

upstream siad {
	server sia:9980;
}

server {
	listen 80 default_server;
	listen [::]:80 default_server;

	# understand the regex https://regex101.com/r/BGQvi6/6
	server_name "~^(((?<base32_subdomain>([a-z0-9]{55}))|(?<hns_domain>[^\.]+)\.hns)\.)?((?<portal_domain>[^.]+)\.)?(?<domain>[^.]+)\.(?<tld>[^.]+)$";

	# ddos protection: closing slow connections
	client_body_timeout 5s;
	client_header_timeout 5s;

	# Increase the body buffer size, to ensure the internal POSTs can always
	# parse the full POST contents into memory.
	client_body_buffer_size 128k;
	client_max_body_size 128k;

	# legacy endpoint rewrite
	rewrite ^/portals /skynet/portals permanent;
	rewrite ^/stats /skynet/stats permanent;
	rewrite ^/skynet/blacklist /skynet/blocklist permanent;

	location / {
		# This is only safe workaround to reroute based on some conditions
		# See https://www.nginx.com/resources/wiki/start/topics/depth/ifisevil/
		recursive_error_pages on;

		# redirect links with base32 encoded skylink in subdomain
		error_page 460 = @base32_subdomain;
		if ($base32_subdomain != "") {
			return 460;
		}

		# redirect links with handshake domain on hns subdomain
		error_page 461 = @hns_domain;
		if ($hns_domain != "") {
			return 461;
		}

		include /etc/nginx/conf.d/include/cors;

		root /var/www/webportal;
	}

	location /docs {
		proxy_pass https://nebulouslabs.github.io/skynet-docs;
	}

	location /skynet/blocklist {
		include /etc/nginx/conf.d/include/cors;

		proxy_cache skynet;
		proxy_cache_valid any 1m; # cache blocklist for 1 minute
		proxy_set_header User-Agent: Sia-Agent;
		proxy_pass http://siad/skynet/blocklist;
	}

	location /skynet/portals {
		include /etc/nginx/conf.d/include/cors;

		proxy_cache skynet;
		proxy_cache_valid any 1m; # cache portals for 1 minute
		proxy_set_header User-Agent: Sia-Agent;
		proxy_pass http://siad/skynet/portals;
	}

	location /skynet/stats {
		include /etc/nginx/conf.d/include/cors;

		set $response_body ''; # we need a variable for full response body (not chuncked)

		# modify the response to add numfiles and totalsize to account for node rotation
		# example prevstats.lua: 'return { numfiles = 12345, totalsize = 123456789 }'
		body_filter_by_lua_block {
			local file_exists = io.open("/data/nginx/skynet/prevstats.lua")
			if file_exists then
				file_exists.close()
				
				-- because response data is chunked, we need to concat ngx.arg[1] until
				-- last chunk is received (when ngx.arg[2] is set to true)
				ngx.var.response_body = ngx.var.response_body .. ngx.arg[1]
				
				if ngx.arg[2] then
					local json = require('cjson')
					local prevstats = require('/data/nginx/skynet/prevstats')
					local stats = json.decode(ngx.var.response_body)
					stats.uploadstats.numfiles = stats.uploadstats.numfiles + prevstats.numfiles
					stats.uploadstats.totalsize = stats.uploadstats.totalsize + prevstats.totalsize
					ngx.arg[1] = json.encode(stats)
				else
					-- do not send any data in this chunk (wait for last chunk)
					ngx.arg[1] = nil
				end
			end
		}

		proxy_cache skynet;
		proxy_cache_valid any 10m; # cache stats for 10 minutes
		proxy_set_header User-Agent: Sia-Agent;
		proxy_read_timeout 5m; # extend the read timeout
		proxy_pass http://siad/skynet/stats;
	}

	location /health-check {
		include /etc/nginx/conf.d/include/cors;

		access_log off; # do not log traffic to health-check endpoint

		proxy_pass http://health-check:3100;
	}

	location /hns {
		include /etc/nginx/conf.d/include/proxy-buffer;

		# variable definititions - we need to define a variable to be able to access it in lua by ngx.var.something
		set $skylink ''; # placeholder for the raw 46 bit skylink
		set $rest ''; # placeholder for the rest of the url that gets appended to skylink (path and args)
		
		# resolve handshake domain by requesting to /hnsres endpoint and assign correct values to $skylink and $rest
		access_by_lua_block {
			local json = require('cjson')
			
			-- match the request_uri and extract the hns domain and anything that is passed in the uri after it
			-- example: /hns/something/foo/bar?baz=1 matches:
			-- > hns_domain_name: something
			-- > request_uri_rest: /foo/bar/?baz=1
			local hns_domain_name, request_uri_rest = string.match(ngx.var.request_uri, "/hns/([^/?]+)(.*)")

			-- make a get request to /hnsres endpoint with the domain name from request_uri
			local hnsres_res = ngx.location.capture("/hnsres/" .. hns_domain_name)

			-- we want to fail with a generic 404 when /hnsres returns anything but 200 OK with a skylink
			if hnsres_res.status ~= ngx.HTTP_OK then
				ngx.exit(ngx.HTTP_NOT_FOUND)
			end

			-- since /hnsres endpoint response is a json, we need to decode it before we access it
			-- example response: '{"skylink":"sia://XABvi7JtJbQSMAcDwnUnmp2FKDPjg8_tTTFP4BwMSxVdEg"}'
			local hnsres_json = json.decode(hnsres_res.body)

			-- define local variable containing rest of the skylink if provided
			local skylink_rest

			if hnsres_json.skylink then
				-- try to match the skylink with sia:// prefix
				skylink, skylink_rest = string.match(hnsres_json.skylink, "sia://([^/?]+)(.*)")

				-- in case the skylink did not match, assume that there is no sia:// prefix and try to match again
				if skylink == nil then
					skylink, skylink_rest = string.match(hnsres_json.skylink, "/?([^/?]+)(.*)")
				end
			elseif hnsres_json.registry then
				local publickey = hnsres_json.registry.publickey
				local datakey = hnsres_json.registry.datakey

				-- make a get request to /skynet/registry endpoint with the credentials from text record
				local registry_res = ngx.location.capture("/skynet/registry/cached?publickey=" .. publickey .. "&datakey=" .. datakey)

				-- we want to fail with a generic 404 when /skynet/registry returns anything but 200 OK
				if registry_res.status ~= ngx.HTTP_OK then
					ngx.exit(ngx.HTTP_NOT_FOUND)
				end

				-- since /skynet/registry endpoint response is a json, we need to decode it before we access it
				local registry_json = json.decode(registry_res.body)
				-- response will contain a hex encoded skylink, we need to decode it
				local data = (registry_json.data:gsub('..', function (cc)
					return string.char(tonumber(cc, 16))
				end))

				skylink = data
			end

			-- fail with a generic 404 if skylink has not been extracted from a valid /hnsres response for some reason
			if not skylink then
				ngx.exit(ngx.HTTP_NOT_FOUND)
			end

			ngx.var.skylink = skylink
			if request_uri_rest == "/" and skylink_rest ~= nil and skylink_rest ~= "" and skylink_rest ~= "/" then
				ngx.var.rest = skylink_rest
			else
				ngx.var.rest = request_uri_rest
			end
		}

		# overwrite the Cache-Control header to only cache for 60s in case the domain gets updated
		more_set_headers 'Cache-Control: public, max-age=60';
		
		# we proxy to another nginx location rather than directly to siad because we don't want to deal with caching here
		proxy_pass http://127.0.0.1/$skylink$rest;

		# in case siad returns location header, we need to replace the skylink with the domain name
		header_filter_by_lua_block {
			if ngx.header.location then
				-- match hns domain from the request_uri
				local hns_domain_name = string.match(ngx.var.request_uri, "/hns/([^/?]+)")

				-- match location redirect part after the skylink
				local location_rest = string.match(ngx.header.location, "[^/?]+(.*)");

				-- because siad will set the location header to ie. XABvi7JtJbQSMAcDwnUnmp2FKDPjg8_tTTFP4BwMSxVdEg/index.html
				-- we need to replace the skylink with the domain_name so we are not redirected to skylink
				ngx.header.location = hns_domain_name .. location_rest
			end
		}
	}

	location /hnsres {
		include /etc/nginx/conf.d/include/cors;

		proxy_pass http://handshake-api:3100;
	}

	# internal registry endpoint that caches calls for a certain period of time
	# it is not suitable for every registry call but some requests might be cached
	# and we are using it currently for caching registry resolutions from /hns calls
	location /skynet/registry/cached {
		internal; # internal endpoint only
		access_log off; # do not log traffic 

		proxy_cache skynet;
		proxy_http_version 1.1; # upgrade if necessary
		proxy_cache_key publickey=$arg_publickey&datakey=$arg_datakey; # cache based on publickey and datakey
		proxy_cache_valid 200 30s; # cache only 200 responses and only for 30 seconds
		proxy_cache_lock on; # queue cache requests for the same resource until it is fully cached
		proxy_cache_bypass $cookie_nocache $arg_nocache; # add cache bypass option
		add_header X-Proxy-Cache $upstream_cache_status; # add response header to indicate cache hits and misses

		proxy_pass http://127.0.0.1/skynet/registry$is_args$args;
	}

	location /skynet/registry {
		include /etc/nginx/conf.d/include/cors;
		include /etc/nginx/conf.d/include/sia-auth;

		limit_req zone=registry_access_by_ip burst=600 nodelay;
		limit_req zone=registry_access_by_ip_throttled burst=200 nodelay;

		proxy_set_header User-Agent: Sia-Agent;
		proxy_read_timeout 600; # siad should timeout with 404 after 5 minutes
		proxy_pass http://siad/skynet/registry;
	}

	location /skynet/skyfile {
		include /etc/nginx/conf.d/include/cors;
		include /etc/nginx/conf.d/include/sia-auth;

		limit_req zone=uploads_by_ip burst=100 nodelay;
		limit_req zone=uploads_by_ip_throttled;

		limit_conn upload_conn 10;
		limit_conn upload_conn_rl 1;

		client_max_body_size 1000M; # make sure to limit the size of upload to a sane value
		proxy_read_timeout 600;
		proxy_request_buffering off; # stream uploaded files through the proxy as it comes in
		proxy_set_header Expect $http_expect;
		proxy_set_header User-Agent: Sia-Agent;

		# Extract 2 sets of 2 characters from $request_id and assign to $dir1, $dir2
		# respectfully. The rest of the $request_id is going to be assigned to $dir3.
		# We use those variables to automatically generate a unique path for the uploaded file.
		# This ensures that not all uploaded files end up in the same directory, which is something
		# that causes performance issues in the renter.
		# Example path result: /af/24/9bc5ec894920ccc45634dc9a8065
		if ($request_id ~* "(\w{2})(\w{2})(\w+)") {
			set $dir1 $1;
			set $dir2 $2;
			set $dir3 $3;
		}

		# proxy this call to siad endpoint (make sure the ip is correct)
		proxy_pass http://siad/skynet/skyfile/$dir1/$dir2/$dir3$is_args$args;
	}

	location ~ "^/(([a-zA-Z0-9-_]{46}|[a-z0-9]{55})(/.*)?)$" {
		include /etc/nginx/conf.d/include/cors;
		include /etc/nginx/conf.d/include/proxy-buffer;
		include /etc/nginx/conf.d/include/proxy-cache-downloads;

		# redirect purge calls to separate location
		error_page 462 = @purge;
		if ($request_method = PURGE) {
			return 462;
		}

		limit_conn downloads_by_ip 100; # ddos protection: max 100 downloads at a time
		add_header Cache-Control "public, max-age=86400"; # allow consumer to cache response

		# we need to explicitly use set directive here because $1 will contain the skylink with
		# decoded whitespaces and set will re-encode it for us before passing it to proxy_pass
		set $skylink $1;

		proxy_read_timeout 600;
		proxy_set_header User-Agent: Sia-Agent;
		# proxy this call to siad /skynet/skylink/ endpoint (make sure the ip is correct)
		proxy_pass http://siad/skynet/skylink/$skylink$is_args$args;
	}

	location @base32_subdomain {
		include /etc/nginx/conf.d/include/proxy-buffer;

		proxy_pass http://127.0.0.1/$base32_subdomain/$request_uri;
	}

	location @hns_domain {
		include /etc/nginx/conf.d/include/proxy-buffer;

		proxy_pass http://127.0.0.1/hns/$hns_domain/$request_uri;
	}

	location @purge {
		allow 10.0.0.0/8;
		allow 127.0.0.1/32;
		allow 172.16.0.0/12;
		allow 192.168.0.0/16;
		deny all;

		set $lua_purge_path "/data/nginx/cache/";
		content_by_lua_file /etc/nginx/conf.d/scripts/purge-multi.lua;
	}

	location ~ "^/file/([a-zA-Z0-9-_]{46}(/.*)?)$" {
		include /etc/nginx/conf.d/include/proxy-buffer;

		rewrite /file/(.*) $1 break; # drop the /file/ prefix from uri

		proxy_pass http://127.0.0.1/$uri?attachment=true&$args;
	}

	# include custom locations, specific to the server
	include /etc/nginx/conf.d/server-override/*;
}