1	import Base
2	import ./date.bend as D
3	
4	type Period.Error is Data:
5	  OutOfRange{}
6	
7	type Period is Data:
8	  Period{years: U32, months: U32, days: U32}
9	
10	def Period.from.y(
11	  +years: U32, +extra: U32, +months: U32, +days: U32, ok: Bool
12	) -> Result<&2, &2, Period.Error, Period>:
13	  match ok:
14	    case False{}:
15	      Fail{OutOfRange{}}
16	    case True{}:
17	      Done{Period{U32.add(years, extra), months, days}}
18	
19	def Period.from(
20	  +years: U32, +months: U32, +days: U32
21	) -> Result<&2, &2, Period.Error, Period>:
22	  +extra = U32.div(months, 12)
23	  Period.from.y(
24	    years, extra, U32.mod(months, 12), days,
25	    U32.is_le(extra, U32.sub(U32.not(0), years))
26	  )
27	
28	def Period.add_to.days(
29	  r: Result<&2, &2, D.Date.Error, D.Date>, pd: U32
30	) -> Result<&2, &2, D.Date.Error, D.Date>:
31	  match r:
32	    case Fail{e}:
33	      Fail{e}
34	    case Done{date}:
35	      D.Date.add_days(date, pd)
36	
37	def Period.add_to.from(
38	  +y: U32, +m: U32, +d: U32, +pd: U32
39	) -> Result<&2, &2, D.Date.Error, D.Date>:
40	  Period.add_to.days(D.Date.from(y, m, d), pd)
41	
42	def Period.add_to.day(
43	  +y: U32, +m: U32, +d: U32, +pd: U32, +dim: U32, le: Bool
44	) -> Result<&2, &2, D.Date.Error, D.Date>:
45	  match le:
46	    case True{}:
47	      Period.add_to.from(y, m, d, pd)
48	    case False{}:
49	      Period.add_to.from(y, m, dim, pd)
50	
51	def Period.add_to.dim(
52	  +y: U32, +m: U32, +d: U32, +pd: U32, dimr: Maybe<&2, U32>
53	) -> Result<&2, &2, D.Date.Error, D.Date>:
54	  match dimr:
55	    case None{}:
56	      Fail{D.OutOfRange{}}
57	    case Some{+dim}:
58	      Period.add_to.day(y, m, d, pd, dim, U32.is_le(d, dim))
59	
60	def Period.add_to.y3(
61	  +y: U32, +m: U32, +d: U32, +pd: U32, ok: Bool
62	) -> Result<&2, &2, D.Date.Error, D.Date>:
63	  match ok:
64	    case False{}:
65	      Fail{D.OutOfRange{}}
66	    case True{}:
67	      Period.add_to.dim(y, m, d, pd, D.Date.dim(m, D.Date.leap(y)))
68	
69	def Period.add_to.y2(
70	  +y: U32, +m: U32, +d: U32, +pd: U32
71	) -> Result<&2, &2, D.Date.Error, D.Date>:
72	  Period.add_to.y3(y, m, d, pd, Bool.and(U32.is_ge(y, 1), U32.is_le(y, 9999)))
73	
74	def Period.add_to.mc(
75	  +y: U32, +m: U32, +d: U32, +pd: U32, ge: Bool
76	) -> Result<&2, &2, D.Date.Error, D.Date>:
77	  match ge:
78	    case False{}:
79	      Period.add_to.y2(y, m, d, pd)
80	    case True{}:
81	      Period.add_to.y2(U32.add(y, 1), U32.sub(m, 12), d, pd)
82	
83	def Period.add_to.ya(
84	  +dy: U32, +py: U32, +dm: U32, +pm: U32, +dd: U32, +pd: U32, ok: Bool
85	) -> Result<&2, &2, D.Date.Error, D.Date>:
86	  match ok:
87	    case False{}:
88	      Fail{D.OutOfRange{}}
89	    case True{}:
90	      +y = U32.add(dy, py)
91	      +m = U32.add(dm, pm)
92	      Period.add_to.mc(y, m, dd, pd, U32.is_gt(m, 12))
93	
94	def Period.add_to.go(
95	  date: D.Date, p: Period
96	) -> Result<&2, &2, D.Date.Error, D.Date>:
97	  match date p:
98	    case D.Date{+dy, +dm, +dd} Period{+py, +pm, +pd}:
99	      Period.add_to.ya(
100	        dy, py, dm, pm, dd, pd, U32.is_le(py, U32.sub(U32.not(0), dy))
101	      )
102	
103	def Period.add_to(
104	  p: Period, date: D.Date
105	) -> Result<&2, &2, D.Date.Error, D.Date>:
106	  Period.add_to.go(date, p)
107	
108	def Period.emonth(+y: U32, +m: U32) -> U32:
109	  U32.add(U32.mul(y, 12), m)
110	
111	def Period.between.ms.from(
112	  +end: D.Date, +tm: U32, r: Result<&2, &2, D.Date.Error, D.Date>
113	) -> Result<&2, &2, Period.Error, Period>:
114	  match r:
115	    case Fail{_}:
116	      Fail{OutOfRange{}}
117	    case Done{start2}:
118	      Period.from(
119	        U32.div(tm, 12),
120	        U32.mod(tm, 12),
121	        U32.sub(D.Date.to_days(end), D.Date.to_days(start2))
122	      )
123	
124	def Period.between.ms.add(
125	  +start: D.Date, +end: D.Date, +tm: U32,
126	  rp: Result<&2, &2, Period.Error, Period>
127	) -> Result<&2, &2, Period.Error, Period>:
128	  match rp:
129	    case Fail{_}:
130	      Fail{OutOfRange{}}
131	    case Done{pM}:
132	      Period.between.ms.from(end, tm, Period.add_to(pM, start))
133	
134	def Period.between.ms(
135	  +start: D.Date, +end: D.Date, +tm: U32
136	) -> Result<&2, &2, Period.Error, Period>:
137	  Period.between.ms.add(start, end, tm, Period.from(0, tm, 0))
138	
139	def Period.between.day(
140	  start: D.Date, end: D.Date, sm: U32, em: U32, borrow: Bool
141	) -> Result<&2, &2, Period.Error, Period>:
142	  match borrow:
143	    case True{}:
144	      Period.between.ms(start, end, U32.sub(U32.sub(em, sm), 1))
145	    case False{}:
146	      Period.between.ms(start, end, U32.sub(em, sm))
147	
148	def Period.between.go(
149	  +start: D.Date, +end: D.Date
150	) -> Result<&2, &2, Period.Error, Period>:
151	  match start end:
152	    case D.Date{+sy, +sm, +sd} D.Date{+ey, +em, +ed}:
153	      Period.between.day(
154	        start, end,
155	        Period.emonth(sy, sm), Period.emonth(ey, em),
156	        U32.is_lt(ed, sd)
157	      )
158	
159	def Period.between.ord(
160	  start: D.Date, end: D.Date, lt: Bool
161	) -> Result<&2, &2, Period.Error, Period>:
162	  match lt:
163	    case True{}:
164	      Fail{OutOfRange{}}
165	    case False{}:
166	      Period.between.go(start, end)
167	
168	def Period.between(
169	  +start: D.Date, +end: D.Date
170	) -> Result<&2, &2, Period.Error, Period>:
171	  Period.between.ord(start, end, D.Date.is_lt(end, start))