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

# this runs before forking out nginx worker processes
init_by_lua_block { 
	require "cjson" 
	require "socket.http"
}

# 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;

# skynet-jwt contains dash so we cannot use $cookie_skynet-jwt
# https://richardhart.me/2012/03/18/logging-nginx-cookies-with-dashes/
map $http_cookie $skynet_jwt {
	default '';
	~skynet-jwt=(?<match>[^\;]+) $match;
}

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;
	rewrite ^/account/(.*) https://account.$domain.$tld/$1 permanent;

	# 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;
	}

	# redirect to dnslookup endpoint
	error_page 462 = @dnslink_lookup;
	if ($http_dnslink_lookup) {
		return 462;
	}

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

		proxy_pass http://website:9000;
	}

	location /docs {
		proxy_pass https://skynetlabs.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;

		proxy_cache skynet;
		proxy_cache_valid any 1m; # cache stats for 1 minute
		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://10.10.10.60:3100; # hardcoded ip because health-check waits for nginx
	}

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

		# 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
		}

		# 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 {
		include /etc/nginx/conf.d/include/proxy-pass-internal;
		
		internal; # internal endpoint only
		access_log off; # do not log traffic

		proxy_cache skynet;
		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

		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;
		include /etc/nginx/conf.d/include/track-registry;

		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;

		access_by_lua_block {
			-- this block runs only when accounts are enabled
			if os.getenv("ACCOUNTS_ENABLED", "0") == "0" then return end

			local res = ngx.location.capture("/accounts/user/limits", { copy_all_vars = true })
			if res.status == ngx.HTTP_OK then
				local json = require('cjson')
				local limits = json.decode(res.body)
				if limits.registry > 0 then
					ngx.sleep(limits.registry / 1000)
				end
			end
		}
	}

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

		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

		# increase request timeouts
		proxy_read_timeout 600;
		proxy_send_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;

		# access_by_lua_block {
		# 	-- this block runs only when accounts are enabled
		# 	if os.getenv("ACCOUNTS_ENABLED", "0") == "0" then return end

		# 	ngx.var.upload_limit_rate = 5 * 1024 * 1024
		# 	local res = ngx.location.capture("/accounts/user", { copy_all_vars = true })
		# 	if res.status == ngx.HTTP_OK then
		# 		local json = require('cjson')
		# 		local user = json.decode(res.body)
		# 		ngx.var.upload_limit_rate = ngx.var.upload_limit_rate * (user.tier + 1)
		# 	end
		# }

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

	# endpoing implementing resumable file uploads open protocol https://tus.io
	location /skynet/tus {
		include /etc/nginx/conf.d/include/cors;
		include /etc/nginx/conf.d/include/track-upload;

		client_max_body_size 50M; # tus chunks size is 40M + leaving 10M of breathing room

		# increase request timeouts
		proxy_read_timeout 600;
		proxy_send_timeout 600;

		proxy_request_buffering off; # stream uploaded files through the proxy as it comes in
		proxy_set_header Expect $http_expect;

		# rewrite proxy request to use correct host uri from env variable (required to return correct location header)
		set_by_lua $SKYNET_SERVER_API 'return os.getenv("SKYNET_SERVER_API")';
		proxy_redirect https://siad $SKYNET_SERVER_API;

		# proxy /skynet/tus requests to siad endpoint with all arguments
		proxy_pass http://siad;

		# set max upload size dynamically based on account limits
		rewrite_by_lua_block {
			-- set default limit value to 1 GB
			ngx.req.set_header("SkynetMaxUploadSize", 1073741824)

			-- this block runs only when accounts are enabled
			if os.getenv("ACCOUNTS_ENABLED", "0") == "0" then return end

			-- fetch account limits and set max upload size accordingly
			local res = ngx.location.capture("/accounts/user/limits", { copy_all_vars = true })
			if res.status == ngx.HTTP_OK then
				local json = require('cjson')
				local limits = json.decode(res.body)
				ngx.req.set_header("SkynetMaxUploadSize", limits.maxUploadSize)
			end
		}

		# extract skylink from base64 encoded upload metadata and assign to a proper header
		header_filter_by_lua_block {
			if ngx.header["Upload-Metadata"] then
				local encodedSkylink = string.match(ngx.header["Upload-Metadata"], "Skylink ([^,?]+)")

				if encodedSkylink then
					ngx.header["Skynet-Skylink"] = ngx.decode_base64(encodedSkylink)
				end
			end
		}
	}

	location /skynet/pin {
		include /etc/nginx/conf.d/include/cors;
		include /etc/nginx/conf.d/include/sia-auth;
		include /etc/nginx/conf.d/include/track-upload;
		include /etc/nginx/conf.d/include/generate-siapath;

		proxy_set_header User-Agent: Sia-Agent;
		proxy_pass http://siad$uri?siapath=$dir1/$dir2/$dir3&$args;
	}

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

		proxy_set_header User-Agent: Sia-Agent;
		proxy_pass http://siad;
	}

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

		proxy_set_header User-Agent: Sia-Agent;
		proxy_pass http://siad;
	}

	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;
		include /etc/nginx/conf.d/include/track-download;

		# 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

		# we need to explicitly use set directive here because $2 and $3 will contain values with
		# decoded whitespaces and set will re-encode it for us before passing it to proxy_pass
		set $skylink $2;
		set $path $3;

		# $skylink_v1 and $skylink_v2 variables default to the same value but in case the requested skylink was:
		# a) skylink v1 - it wouldn't matter, no additional logic is executed
		# b) skylink v2 - in a lua block below we will resolve the skylink v2 into skylink v1 and update 
		#      $skylink_v1 variable so then the proxy request to skyd can be cached in nginx (proxy_cache_key 
		#      in proxy-cache-downloads includes $skylink_v1 as a part of the cache key)
		set $skylink_v1 $skylink;
		set $skylink_v2 $skylink;

		access_by_lua_block {
			-- detect whether requested skylink is v2
			local isBase32v2 = string.len(ngx.var.skylink) == 55 and string.sub(ngx.var.skylink, 0, 2) == "04"
			local isBase64v2 = string.len(ngx.var.skylink) == 46 and string.sub(ngx.var.skylink, 0, 2) == "AQ"
			
			if isBase32v2 or isBase64v2 then
				local res = ngx.location.capture("/skynet/resolve/" .. ngx.var.skylink_v2)
				if res.status == ngx.HTTP_OK then
					local json = require('cjson')
					local resolve = json.decode(res.body)
					ngx.var.skylink_v1 = resolve.skylink
				end
			end

			-- this block runs only when accounts are enabled
			if os.getenv("ACCOUNTS_ENABLED", "0") == "0" then return end

			local res = ngx.location.capture("/accounts/user/limits", { copy_all_vars = true })
			if res.status == ngx.HTTP_OK then
				local json = require('cjson')
				local limits = json.decode(res.body)
				ngx.var.limit_rate = limits.download
			end
		}

		proxy_read_timeout 600;
		proxy_set_header User-Agent: Sia-Agent;
		
		proxy_pass http://siad/skynet/skylink/$skylink$path$is_args$args;
	}

	location @dnslink_lookup {
		include /etc/nginx/conf.d/include/proxy-buffer;
		include /etc/nginx/conf.d/include/proxy-pass-internal;

		set $dnslink '';

		rewrite_by_lua_block {
			local http = require("socket.http")
			local ok, statusCode, headers, statusText = http.request {
				url = "http://dnslink-api:3100/dnslink/" .. ngx.var.host
			}

			if statusCode == ngx.HTTP_OK then
				ngx.var.dnslink = headers["skynet-skylink"]
			else
				ngx.status = statusCode
				ngx.header["content-type"] = "text/plain"
				ngx.say(headers["dnslink-error"])
				ngx.exit(statusCode)
			end
		}

		proxy_set_header Dnslink-Lookup "";
		proxy_pass http://127.0.0.1/$dnslink$request_uri;
	}

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

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

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

		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;
		include /etc/nginx/conf.d/include/proxy-pass-internal;

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

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

	location /__internal/do/not/use/authenticated {
		include /etc/nginx/conf.d/include/cors;

		charset utf-8;
    	charset_types application/json;
    	default_type application/json;

		content_by_lua_block {
			local json = require('cjson')
			-- this block runs only when accounts are enabled
			if os.getenv("ACCOUNTS_ENABLED", "0") == "0" then
				ngx.say(json.encode{authenticated = false})
				return ngx.exit(ngx.HTTP_OK)
			end

			local res = ngx.location.capture("/accounts/user", { copy_all_vars = true })
			if res.status == ngx.HTTP_OK then
				local limits = json.decode(res.body)
				ngx.say(json.encode{authenticated = limits.tier > 0})
				return ngx.exit(ngx.HTTP_OK)
			end

			ngx.say(json.encode{authenticated = false})
			return ngx.exit(ngx.HTTP_OK)
		}
	}

	location /accounts {
		internal; # internal endpoint only
		access_log off; # do not log traffic

		proxy_cache skynet; # use general nginx cache
		proxy_cache_key $uri+$skynet_jwt; # include skynet-jwt cookie (mapped to skynet_jwt)
		proxy_cache_valid 200 401 1m; # cache success and unauthorized responses for 1 minute

		rewrite /accounts(.*) $1 break; # drop the /accounts prefix from uri
		proxy_pass http://10.10.10.70:3000; # hardcoded ip because accounts might not be available
	}

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