1	# fetch/run: the interpreter for `ez fetch`. It reads whether there is an
2	# ez.toml and the lock's text into a World, with the directory they are in,
3	# then loops: it asks the planner (fetch/plan.bend) what is still open,
4	# answers each question, and adds the answers to the World, until nothing is
5	# left to ask. Then it runs the planner's plan with the lock's effect runner
6	# (`Run.exec.plan`), which lays each tree and exits 1 with the reason when
7	# the plan refuses. A tree under BEND_LIB is read here as the lock reads one
8	# (`Run.answer.lib`), a hub package is fetched as the lock fetches one
9	# (`Run.answer`), and a checkout is made as `ez add` makes one
10	# (`Run.answer.up` of `Up.Clone`), in a scratch directory outside the project
11	# and BEND_LIB that is removed whether or not the clone worked. A name's file
12	# under `BEND_LIB/names` is read as it is. So nothing is
13	# written while the questions are answered, and a refused fetch leaves
14	# BEND_LIB as it found it. It decides nothing; that it reads and executes
15	# faithfully is EZ-TRUST-2.
16	import Base
17	import 0xead4c7939c9eaca8d47da53b4496b731/main.bend as R
18	import ../io/file.bend as F
19	import ../lock/run.bend as Run
20	import ../lock/world.bend as W
21	import ../lock/up.bend as Up
22	import ./world.bend as FW
23	import ./plan.bend as FP
24	
25	# a tree's manifest, when there is one: the tree as it names it, and
26	# otherwise a miss
27	def laid.seen(got: Maybe<&2, String>, +dir: String) -> IO(W.Answer):
28	  match got:
29	    case None{}:
30	      IO.pure(W.Answer, W.Miss{"ez: " ++ dir ++ " is not there"})
31	    case Some{text}:
32	      Run.answer.lib(dir, text)
33	
34	# the tree under BEND_LIB for a hash, as its manifest names it, or a miss
35	# when there is none
36	def laid(+lib: String, +hash: String) -> IO(W.Answer):
37	  +dir = lib ++ "/" ++ hash
38	  do IO<W.Answer>:
39	    m : Maybe<&2, String> <- F.read(dir ++ "/manifest")
40	    laid.seen(m, dir)
41	
42	# one question, answered
43	def answer(+lib: String, ask: FW.Ask) -> IO(FW.Answer):
44	  match ask:
45	    case FW.Laid{hash}:
46	      do IO<FW.Answer>:
47	        a : W.Answer <- laid(lib, hash)
48	        return FW.Read{a}
49	    case FW.Git{_hash, q}:
50	      do IO<FW.Answer>:
51	        a : Up.Answer <- Run.answer.up(lib, q)
52	        return FW.Said{a}
53	    case FW.Hub{q}:
54	      do IO<FW.Answer>:
55	        a : W.Answer <- Run.answer(lib, q)
56	        return FW.Read{a}
57	    case FW.Named{nv}:
58	      do IO<FW.Answer>:
59	        m : Maybe<&2, String> <- F.read(lib ++ "/names/" ++ nv)
60	        return FW.Held{m}
61	
62	# every question, answered
63	def answer.all(+lib: String, asks: List<&2, FW.Ask>) -> IO(List<&2, FW.Reply>):
64	  match asks:
65	    case []:
66	      IO.pure(List<&2, FW.Reply>, [])
67	    case +h <> t:
68	      do IO<List<&2, FW.Reply>>:
69	        a : FW.Answer <- answer(lib, h)
70	        rest : List<&2, FW.Reply> <- answer.all(lib, t)
71	        return FW.Reply{h, a} <> rest
72	
73	# the World with more answers in it
74	def more(world: FW.World, rs: List<&2, FW.Reply>) -> FW.World:
75	  FW.World{here, ledger, lock, replies} = world
76	  FW.World{here, ledger, lock, List.append(&2, FW.Reply, replies, rs)}
77	
78	# the planner's step: its questions answered and the loop gone round again,
79	# or its plan run
80	def loop.step(st: FP.Step, +lib: String, world: FW.World, go: FW.World -> IO(Unit)) -> IO(Unit):
81	  match st:
82	    case FP.Asking{asks}:
83	      do IO<Unit>:
84	        rs : List<&2, FW.Reply> <- answer.all(lib, asks)
85	        go(more(world, rs))
86	    case FP.Run{pl}:
87	      Run.exec.plan(lib, pl)
88	
89	# the rounds the loop may take. A package asks at most twice, for its tree
90	# under BEND_LIB and for its fetch, and a round asks for every package at
91	# once, so this is only a guard against a planner that keeps asking, and
92	# running out of it dies loudly.
93	def rounds() -> Nat:
94	  U32.to_nat(10)
95	
96	# the loop, under fuel. A package asks at most twice, for its tree under
97	# BEND_LIB and for its fetch, and every round answers what it asked, so the
98	# fuel is only a guard.
99	def loop(fuel: Nat, +lib: String, +world: FW.World) -> IO(Unit):
100	  match fuel:
101	    case 0n:
102	      IO.die(Unit, 1, "ez: ez fetch kept asking questions")
103	    case 1n+f:
104	      loop.step(FP.step(world), lib, world, w => loop(f, lib, w))
105	
106	# a file of the project, read
107	def at(+here: String, +file: String) -> String:
108	  here ++ "/" ++ file
109	
110	# BEND_LIB `lib` filled from the lock of the project in `here`, which is
111	# where every relative path in the lock is read from. `ez tool` fills a
112	# tool's cache from its checkout's lock this way.
113	def fill(+here: String, +lib: String) -> IO(Unit):
114	  do IO<Unit>:
115	    led : Maybe<&2, String> <- F.read(at(here, FW.toml()))
116	    lk : Maybe<&2, String> <- F.read(at(here, FW.lockfile()))
117	    loop(rounds(), lib, FW.World{here, Maybe.is_some(&2, String, led), lk, []})
118	
119	# `ez fetch`: BEND_LIB filled from the lock of the project ez runs in
120	def run() -> IO(Unit):
121	  do IO<Unit>:
122	    lib : String <- Run.bend.lib()
123	    +pwd : String <- R.exec(["pwd"])
124	    fill(String.trim(R.text(pwd)), lib)