1	# ledger/upgrade: what `ez lock --upgrade` may do to one dependency, before
2	# it talks to a remote. The ledger pins exact commits. A tag is the only
3	# floating name a person wrote down, so that is what gets re-resolved. A pin
4	# with no tag fast-forwards to the default branch tip when the commit is an
5	# ancestor of it, and stays a commit pin. A hub package is the hash itself.
6	# `vend` says the tree under `.ez/lib/<hash>` is committed, so a move lays the
7	# new tree there; the allowlist that names it is `ledger/ignore.bend`'s,
8	# derived from the ledger the move writes. A move also rewrites an
9	# `import 0x<hash>/` line that names the old hash.
10	import Base
11	import ./manifest.bend as M
12	
13	# what an upgrade will ask the remote, once the ledger has been read
14	type Aim is Data:
15	  Hold{}
16	  Follow{+ref: String}
17	  Forward{}
18	
19	# what that answer means for the pin
20	type Verdict is Data:
21	  Keep{}
22	  Drift{}
23	  Off{}
24	  Advance{rev: String, tag: String}
25	
26	# one hash that moved, and the hash that replaces it: an import line to
27	# rewrite, or a committed tree to remove
28	type Swap is Data:
29	  Swap{old: String, new: String}
30	
31	# an empty `--package` is every dependency; a name is that one
32	def chosen.go(all: Bool, +only: String, +name: String) -> Bool:
33	  match all:
34	    case True{}:
35	      True{}
36	    case False{}:
37	      String.eq(only, name)
38	
39	# an empty `--package` is every dependency; a name is that one
40	def chosen(+only: String, +name: String) -> Bool:
41	  chosen.go(String.is_empty(only), only, name)
42	
43	# the rest of the scan only when this one was not it
44	def known.step(hit: Bool, rest: Unit -> Bool) -> Bool:
45	  match hit:
46	    case True{}:
47	      True{}
48	    case False{}:
49	      rest(Unit{})
50	
51	# whether the ledger names this dependency
52	def known.in(ds: List<&2, M.Dep>, +name: String) -> Bool:
53	  match ds:
54	    case []:
55	      False{}
56	    case +h <> t:
57	      known.step(String.eq(M.dep.name(h), name), _u => known.in(t, name))
58	
59	# `--package` with no such dependency is a mistake, and no filter is not
60	def known.go(all: Bool, ds: List<&2, M.Dep>, +name: String) -> Bool:
61	  match all:
62	    case True{}:
63	      True{}
64	    case False{}:
65	      known.in(ds, name)
66	
67	# whether the ledger names the dependency `--package` asked for
68	def known(+only: String, ds: List<&2, M.Dep>) -> Bool:
69	  known.go(String.is_empty(only), ds, only)
70	
71	# a selected git pin with no tag follows the default branch
72	def aim.tag(bare: Bool, +tag: String) -> Aim:
73	  match bare:
74	    case True{}:
75	      Forward{}
76	    case False{}:
77	      Follow{tag}
78	
79	# a selected hub pin has nothing to follow
80	def aim.src(source: M.Source) -> Aim:
81	  match source:
82	    case M.Hub{_named}:
83	      Hold{}
84	    case M.Git{_url, _rev, +tag, _root, _nar, _vend}:
85	      aim.tag(String.is_empty(tag), tag)
86	    case M.Member{_path, _named}:
87	      Hold{}
88	
89	# what this dependency is asked. Unselected dependencies are left alone,
90	# including a git one, so `--package` does not move its neighbours.
91	def aim(sel: Bool, source: M.Source) -> Aim:
92	  match sel:
93	    case False{}:
94	      Hold{}
95	    case True{}:
96	      aim.src(source)
97	
98	# the same commit either still hashes to the pin or it does not
99	def judge.same(agree: Bool) -> Verdict:
100	  match agree:
101	    case True{}:
102	      Keep{}
103	    case False{}:
104	      Drift{}
105	
106	# a different commit is the upgrade only when it descends from the pin
107	def judge.move(onward: Bool, +rev: String, +tag: String) -> Verdict:
108	  match onward:
109	    case True{}:
110	      Advance{rev, tag}
111	    case False{}:
112	      Off{}
113	
114	# `same` is the resolved commit against the pin. `onward` is that commit
115	# being a descendant of the pin. `agree` is the recomputed hash, NAR hash
116	# and root against what the ledger recorded, and it only matters when the
117	# commit did not move.
118	def judge(same: Bool, onward: Bool, agree: Bool, rev: String, tag: String) -> Verdict:
119	  match same:
120	    case True{}:
121	      judge.same(agree)
122	    case False{}:
123	      judge.move(onward, rev, tag)
124	
125	# the three fields a checkout can disagree on, each required
126	def agree.nar(same_nar: Bool, same_root: Bool) -> Bool:
127	  match same_nar:
128	    case False{}:
129	      False{}
130	    case True{}:
131	      same_root
132	
133	# whether a recomputed pin is the one the ledger already recorded
134	def agree.go(same_hash: Bool, same_nar: Bool, same_root: Bool) -> Bool:
135	  match same_hash:
136	    case False{}:
137	      False{}
138	    case True{}:
139	      agree.nar(same_nar, same_root)
140	
141	# whether a recomputed pin is the one the ledger already recorded
142	def agree(+oh: String, +nh: String, +onar: String, +nnar: String, +oroot: String, +nroot: String) -> Bool:
143	  agree.go(String.eq(oh, nh), String.eq(onar, nnar), String.eq(oroot, nroot))
144	
145	# a hub miss is a different digest only when the body arrived and hashed
146	# wrong. A package the hub has never seen is not that.
147	def hub.bad(+why: String) -> Bool:
148	  String.contains(why, "does not hash")
149	
150	# the dependency with a new commit written in, and the name, the entry, the
151	# tag and the vendor bit left as they were
152	def retarget.go(
153	  +name: String,
154	  +entry: String,
155	  source: M.Source,
156	  +rev: String,
157	  +hash: String,
158	  +root: String,
159	  +nar: String
160	) -> M.Dep:
161	  match source:
162	    case M.Hub{named}:
163	      M.Dep{name, hash, entry, M.Hub{named}}
164	    case M.Git{url, _rev, tag, _root, _nar, vend}:
165	      M.Dep{name, hash, entry, M.Git{url, rev, tag, root, nar, vend}}
166	    case M.Member{path, named}:
167	      M.Dep{name, hash, entry, M.Member{path, named}}
168	
169	# the dependency with a new commit written in
170	def retarget(dep: M.Dep, +rev: String, +hash: String, +root: String, +nar: String) -> M.Dep:
171	  M.Dep{n, _h, e, s} = dep
172	  retarget.go(n, e, s, rev, hash, root, nar)
173	
174	# what an import line that names a package starts with: `import <hash>/`.
175	# `import 0x<hash>/<file>.bend as P` is the only shape bend has, and the match
176	# is exact at column 0, so an indented import is not rewritten, and neither is
177	# a line that names the hash with no `/` after it.
178	def reimport.head(+hash: String) -> String:
179	  String.append("import ", String.append(hash, "/"))
180	
181	# an empty hash names no package, so it rewrites nothing
182	def reimport.hit(empty: Bool, +line: String, +old: String) -> Bool:
183	  match empty:
184	    case True{}:
185	      False{}
186	    case False{}:
187	      String.starts_with(line, reimport.head(old))
188	
189	# one line, with the branch already chosen. A match cannot scrutinise a call.
190	def reimport.line.go(hit: Bool, +line: String, +old: String, +new: String) -> String:
191	  match hit:
192	    case True{}:
193	      String.append(reimport.head(new),
194	        String.drop(line, String.length(reimport.head(old))))
195	    case False{}:
196	      line
197	
198	# one line, with its import hash rewritten when the line names the old one
199	def reimport.line(+line: String, +old: String, +new: String) -> String:
200	  reimport.line.go(reimport.hit(String.is_empty(old), line, old), line, old, new)
201	
202	# one line through every replacement, in order
203	def reimport.many.line(ss: List<&2, Swap>, +line: String) -> String:
204	  match ss:
205	    case []:
206	      line
207	    case Swap{+old, +new} <> t:
208	      reimport.many.line(t, reimport.line(line, old, new))
209	
210	# every line, in order
211	def reimport.many.lines(+ss: List<&2, Swap>, ls: List<&2, String>) -> List<&2, String>:
212	  match ls:
213	    case []:
214	      []
215	    case +h <> t:
216	      reimport.many.line(ss, h) <> reimport.many.lines(ss, t)
217	
218	# a source file with every moved import hash replaced, in order. The text is
219	# cut at its newlines once and joined back with them, so a line that names no
220	# moved hash is left as it was, and so is the newline the file ends with, or
221	# its lack of one.
222	def reimport.many(+ss: List<&2, Swap>, +text: String) -> String:
223	  String.join(reimport.many.lines(ss, String.lines(text)), "\n")