1	# ezhttp/src/client: fetch a URL. URL and HTTP parsing joined to the wire effect.
2	# Answers a structured Response (status + headers + body), not a hub-style
3	# "0\n…" string contract.
4	import Base
5	import ./url.bend as Url
6	import ./http.bend as Http
7	import ./body.bend as Body
8	import ./wire.bend as Wire
9	import ./wirespec.bend as Spec
10	import ./redirect.bend as Redirect
11	import ./auth.bend as Auth
12	
13	# structured client result: transport/parse error, or an HTTP response
14	type Response is Data:
15	  Err{why: String}
16	  Response{status: U32, headers: List<&2, Http.Header>, body: String}
17	
18	# a torn or successful HTTP parse as a client Response
19	def from.reply(r: Http.Reply) -> Response:
20	  match r:
21	    case Http.Torn{why}:
22	      Err{why}
23	    case Http.Reply{status, headers, body}:
24	      Response{status, headers, body}
25	
26	# an exchange's answer as a client Response, read by the request's method
27	# (wirespec.bend wire.heard: interim 1xx heads skipped, no body for HEAD,
28	# 1xx, 204 or 304; a failed exchange keeps its reason)
29	def http.heard(+method: String, +raw: String) -> Response:
30	  from.reply(Spec.wire.heard(method, raw))
31	
32	# an exchange as wirespec.bend wrote it, with the body's tail of octets: sent
33	# and read by its own method, or the URL's reason
34	def http.send(ex: Spec.Exchange, tail: List<&2, U32>) -> IO(Response):
35	  match ex:
36	    case Spec.NoUrl{why}:
37	      IO.pure(Response, Err{why})
38	    case Spec.Exchange{secure, host, port, +method, req}:
39	      do IO<Response>:
40	        +raw : String <- Wire.wire.talk(secure, host, port, method, req, tail)
41	        IO.pure(Response, http.heard(method, raw))
42	
43	# a URL that came apart (or not) into an HTTP exchange with this body
44	def http.loc(method: String, l: Url.Loc, headers: List<&2, Http.Header>,
45	  +body: Body.Body) -> IO(Response):
46	  http.send(Spec.wire.exchange.body(method, l, headers, body),
47	    Spec.wire.tail(body))
48	
49	# an exchange as wirespec.bend wrote it, bounded by a timeout, sent and read
50	# by its own method
51	def http.send.timed(ms: U32, ex: Spec.Exchange, tail: List<&2, U32>)
52	  -> IO(Response):
53	  match ex:
54	    case Spec.NoUrl{why}:
55	      IO.pure(Response, Err{why})
56	    case Spec.Exchange{secure, host, port, +method, req}:
57	      do IO<Response>:
58	        +raw : String <- Wire.wire.talk.timed(secure, ms, host, port, method,
59	          req, tail)
60	        IO.pure(Response, http.heard(method, raw))
61	
62	# a request with this method, headers and body, bounded by a timeout in
63	# milliseconds
64	def client.timed(method: String, url: String, headers: List<&2, Http.Header>,
65	  +body: Body.Body, ms: U32) -> IO(Response):
66	  http.send.timed(ms, Spec.wire.exchange.body(method, Url.parse(url), headers,
67	    body), Spec.wire.tail(body))
68	
69	# GET bounded by a timeout in milliseconds
70	def client.get.timed(url: String, headers: List<&2, Http.Header>, ms: U32)
71	  -> IO(Response):
72	  client.timed("GET", url, headers, Body.Empty{}, ms)
73	
74	# the next hop after a response (redirect.bend); a failed exchange stops
75	def client.hop(left: Nat, url: String, r: Response) -> Redirect.Hop:
76	  match r:
77	    case Err{why}:
78	      Redirect.Stop{}
79	    case Response{status, headers, body}:
80	      Redirect.redirect.plan(left, url, status, headers)
81	
82	# a response, or the GET its hop asks for
83	def client.after(hop: Redirect.Hop, r: Response, go: String -> IO(Response))
84	  -> IO(Response):
85	  match hop:
86	    case Redirect.Stop{}:
87	      IO.pure(Response, r)
88	    case Redirect.Go{next}:
89	      go(next)
90	
91	# GET, following redirects while `left` hops remain; `body` goes with this
92	# hop only. The answer is the last response, which is a redirect only when
93	# the hops ran out or its Location is not one redirect.bend follows
94	def client.follow(+left: Nat, +url: String, +headers: List<&2, Http.Header>,
95	  body: Body.Body, +ms: U32) -> IO(Response):
96	  match left:
97	    case 0n:
98	      client.timed("GET", url, headers, body, ms)
99	    case 1n+p:
100	      do IO<Response>:
101	        +r : Response <- client.timed("GET", url, headers, body, ms)
102	        client.after(client.hop(left, url, r), r,
103	          next => client.follow(p, next, headers, Body.Empty{}, ms))
104	
105	# a request once it is known whether it follows redirects
106	def client.request.go(go: Bool, method: String, url: String,
107	  headers: List<&2, Http.Header>, body: Body.Body, ms: U32) -> IO(Response):
108	  match go:
109	    case True{}:
110	      client.follow(Redirect.redirect.max(), url, headers, body, ms)
111	    case False{}:
112	      client.timed(method, url, headers, body, ms)
113	
114	# a request with a method, headers, body and timeout; it follows redirects
115	# when `follow` is set and the method is GET (redirect.bend
116	# redirect.follows), and answers its first response otherwise
117	def client.request.opts(+method: String, url: String,
118	  headers: List<&2, Http.Header>, body: Body.Body, ms: U32, follow: Bool)
119	  -> IO(Response):
120	  client.request.go(Redirect.redirect.follows(method, follow), method, url,
121	    headers, body, ms)
122	
123	# GET with headers and a timeout, following redirects when `follow` is set
124	def client.get.opts(url: String, headers: List<&2, Http.Header>, ms: U32,
125	  follow: Bool) -> IO(Response):
126	  client.request.opts("GET", url, headers, Body.Empty{}, ms, follow)
127	
128	# whether a response is the failure of an exchange that ran out of time
129	def client.timed_out(r: Response) -> Bool:
130	  match r:
131	    case Err{why}:
132	      Spec.wire.timed_out(why)
133	    case Response{status, headers, body}:
134	      False{}
135	
136	# GET
137	def client.get(url: String, headers: List<&2, Http.Header>) -> IO(Response):
138	  http.loc("GET", Url.parse(url), headers, Body.Empty{})
139	
140	# HEAD (RFC 9110 §9.3.2)
141	def client.head(url: String, headers: List<&2, Http.Header>) -> IO(Response):
142	  http.loc("HEAD", Url.parse(url), headers, Body.Empty{})
143	
144	# POST
145	def client.post(url: String, headers: List<&2, Http.Header>, body: Body.Body)
146	  -> IO(Response):
147	  http.loc("POST", Url.parse(url), headers, body)
148	
149	# PUT
150	def client.put(url: String, headers: List<&2, Http.Header>, body: Body.Body)
151	  -> IO(Response):
152	  http.loc("PUT", Url.parse(url), headers, body)
153	
154	# DELETE
155	def client.delete(url: String, headers: List<&2, Http.Header>, body: Body.Body)
156	  -> IO(Response):
157	  http.loc("DELETE", Url.parse(url), headers, body)
158	
159	# OPTIONS
160	def client.options(url: String, headers: List<&2, Http.Header>) -> IO(Response):
161	  http.loc("OPTIONS", Url.parse(url), headers, Body.Empty{})
162	
163	# Authorization: Bearer … (auth.bend)
164	def client.bearer(token: String) -> Http.Header:
165	  Auth.auth.bearer(token)
166	
167	# Authorization: Basic … (auth.bend; RFC 7617, RFC 4648 Base64)
168	def client.basic(user: String, password: String) -> Http.Header:
169	  Auth.auth.basic(user, password)