1	import Base
2	import ./date.bend as D
3	
4	type IsoWeek is Data:
5	  IsoWeek{year: U32, week: U32}
6	
7	def IsoWeek.start(d: D.Date) -> Result<&2, &2, D.Date.Error, D.Date>:
8	  D.Date.previous_or_same_weekday(d, D.Mon{})
9	
10	def IsoWeek.from_date.week(
11	  +d: D.Date, +year: U32, r: Result<&2, &2, D.Date.Error, D.Date>
12	) -> Result<&2, &2, D.Date.Error, IsoWeek>:
13	  match r:
14	    case Fail{e}:
15	      Fail{e}
16	    case Done{mon1}:
17	      Done{
18	        IsoWeek{
19	          year,
20	          U32.add(
21	            1, U32.div(U32.sub(D.Date.to_days(d), D.Date.to_days(mon1)), 7)
22	          )
23	        }
24	      }
25	
26	def IsoWeek.from_date.mon1(
27	  +d: D.Date, +year: U32, r: Result<&2, &2, D.Date.Error, D.Date>
28	) -> Result<&2, &2, D.Date.Error, IsoWeek>:
29	  match r:
30	    case Fail{e}:
31	      Fail{e}
32	    case Done{jan4}:
33	      IsoWeek.from_date.week(d, year, IsoWeek.start(jan4))
34	
35	def IsoWeek.from_date.year(
36	  +d: D.Date, r: Result<&2, &2, D.Date.Error, D.Date>
37	) -> Result<&2, &2, D.Date.Error, IsoWeek>:
38	  match r:
39	    case Fail{e}:
40	      Fail{e}
41	    case Done{D.Date{+y, _, _}}:
42	      IsoWeek.from_date.mon1(d, y, D.Date.from(y, 1, 4))
43	
44	def IsoWeek.from_date.thu(
45	  +d: D.Date, r: Result<&2, &2, D.Date.Error, D.Date>
46	) -> Result<&2, &2, D.Date.Error, IsoWeek>:
47	  match r:
48	    case Fail{e}:
49	      Fail{e}
50	    case Done{mon}:
51	      IsoWeek.from_date.year(d, D.Date.add_days(mon, 3))
52	
53	def IsoWeek.from_date(+d: D.Date) -> Result<&2, &2, D.Date.Error, IsoWeek>:
54	  IsoWeek.from_date.thu(d, IsoWeek.start(d))
55	
56	def IsoWeek.from.ok(
57	  got: D.Date, eq: Bool
58	) -> Result<&2, &2, D.Date.Error, D.Date>:
59	  match eq:
60	    case True{}:
61	      Done{got}
62	    case False{}:
63	      Fail{D.OutOfRange{}}
64	
65	def IsoWeek.from.eq(
66	  +year: U32, +week: U32, +got: D.Date,
67	  r: Result<&2, &2, D.Date.Error, IsoWeek>
68	) -> Result<&2, &2, D.Date.Error, D.Date>:
69	  match r:
70	    case Fail{e}:
71	      Fail{e}
72	    case Done{IsoWeek{+y2, +w2}}:
73	      IsoWeek.from.ok(
74	        got, Bool.and(U32.is_eq(y2, year), U32.is_eq(w2, week))
75	      )
76	
77	def IsoWeek.from.chk(
78	  +year: U32, +week: U32, r: Result<&2, &2, D.Date.Error, D.Date>
79	) -> Result<&2, &2, D.Date.Error, D.Date>:
80	  match r:
81	    case Fail{e}:
82	      Fail{e}
83	    case Done{+got}:
84	      IsoWeek.from.eq(year, week, got, IsoWeek.from_date(got))
85	
86	def IsoWeek.from.add(
87	  +year: U32, +week: U32, weekday: D.Weekday, mon1: D.Date
88	) -> Result<&2, &2, D.Date.Error, D.Date>:
89	  IsoWeek.from.chk(
90	    year, week,
91	    D.Date.add_days(
92	      mon1,
93	      U32.add(U32.mul(U32.sub(week, 1), 7), D.Weekday.to_u32(weekday))
94	    )
95	  )
96	
97	def IsoWeek.from.le(
98	  +year: U32, +week: U32, weekday: D.Weekday, mon1: D.Date, ok: Bool
99	) -> Result<&2, &2, D.Date.Error, D.Date>:
100	  match ok:
101	    case False{}:
102	      Fail{D.OutOfRange{}}
103	    case True{}:
104	      IsoWeek.from.add(year, week, weekday, mon1)
105	
106	def IsoWeek.from.mon1(
107	  +year: U32, +week: U32, weekday: D.Weekday,
108	  r: Result<&2, &2, D.Date.Error, D.Date>
109	) -> Result<&2, &2, D.Date.Error, D.Date>:
110	  match r:
111	    case Fail{e}:
112	      Fail{e}
113	    case Done{mon1}:
114	      IsoWeek.from.le(
115	        year, week, weekday, mon1,
116	        U32.is_le(U32.sub(week, 1), U32.div(U32.not(0), 7))
117	      )
118	
119	def IsoWeek.from.jan4(
120	  +year: U32, +week: U32, weekday: D.Weekday,
121	  r: Result<&2, &2, D.Date.Error, D.Date>
122	) -> Result<&2, &2, D.Date.Error, D.Date>:
123	  match r:
124	    case Fail{e}:
125	      Fail{e}
126	    case Done{jan4}:
127	      IsoWeek.from.mon1(year, week, weekday, IsoWeek.start(jan4))
128	
129	def IsoWeek.from.hi(
130	  +year: U32, +week: U32, weekday: D.Weekday, hi: Bool
131	) -> Result<&2, &2, D.Date.Error, D.Date>:
132	  match hi:
133	    case True{}:
134	      Fail{D.OutOfRange{}}
135	    case False{}:
136	      IsoWeek.from.jan4(year, week, weekday, D.Date.from(year, 1, 4))
137	
138	def IsoWeek.from.ge(
139	  +year: U32, +week: U32, weekday: D.Weekday, z: Bool
140	) -> Result<&2, &2, D.Date.Error, D.Date>:
141	  match z:
142	    case True{}:
143	      Fail{D.OutOfRange{}}
144	    case False{}:
145	      IsoWeek.from.hi(year, week, weekday, U32.is_ge(week, 54))
146	
147	def IsoWeek.from(
148	  +year: U32, +week: U32, weekday: D.Weekday
149	) -> Result<&2, &2, D.Date.Error, D.Date>:
150	  IsoWeek.from.ge(year, week, weekday, U32.is_eq(week, 0))