1package ansi
2
3import (
4 "cmp"
5 "slices"
6)
7
8const maxPlannedDamageSpans = 4096
9
10// buildDamagePlan creates the bounded, canonical view of text and clear damage
11// used for terminal emission. The source damage remains untouched because the
12// scroll and shadow paths need its original structural information.
13func buildDamagePlan(frame Frame, damage []Damage, skip *Damage) ([]Span, bool) {
14 if len(damage) == 1 {
15 d := damage[0]
16 if skip != nil && sameDamage(d, *skip) {
17 return nil, false
18 }
19 if d.Kind != DamageText && d.Kind != DamageClear {
20 return nil, false
21 }
22 return buildSingleDamageSpans(frame, d)
23 }
24
25 spans := make([]Span, 0)
26 for _, d := range damage {
27 if skip != nil && sameDamage(d, *skip) {
28 continue
29 }
30 if d.Kind != DamageText && d.Kind != DamageClear {
31 continue
32 }
33 x, y, width, height, ok := clampRect(frame, d.X, d.Y, d.Width, d.Height)
34 if !ok {
35 continue
36 }
37 for row := y; row < y+height; row++ {
38 if len(spans) == maxPlannedDamageSpans {
39 return nil, true
40 }
41 spans = append(spans, Span{Y: row, X: x, Width: width})
42 }
43 }
44
45 slices.SortFunc(spans, func(a, b Span) int {
46 if c := cmp.Compare(a.Y, b.Y); c != 0 {
47 return c
48 }
49 return cmp.Compare(a.X, b.X)
50 })
51
52 return mergeDamageSpans(spans), false
53}
54
55func buildSingleDamageSpans(frame Frame, d Damage) ([]Span, bool) {
56 x, y, width, height, ok := clampRect(frame, d.X, d.Y, d.Width, d.Height)
57 if !ok {
58 return nil, false
59 }
60 if height > maxPlannedDamageSpans {
61 return nil, true
62 }
63 spans := make([]Span, height)
64 for row := range height {
65 spans[row] = Span{Y: y + row, X: x, Width: width}
66 }
67 return spans, false
68}
69
70func mergeDamageSpans(spans []Span) []Span {
71 if len(spans) < 2 {
72 return spans
73 }
74
75 out := spans[:0]
76 for _, span := range spans {
77 if len(out) == 0 {
78 out = append(out, span)
79 continue
80 }
81 last := &out[len(out)-1]
82 // Both endpoints are bounded by frame.Width after clampRect, so these
83 // additions cannot overflow. The comparison includes adjacency.
84 lastEnd := last.X + last.Width
85 spanEnd := span.X + span.Width
86 if span.Y != last.Y || span.X > lastEnd {
87 out = append(out, span)
88 continue
89 }
90 if spanEnd > lastEnd {
91 last.Width = spanEnd - last.X
92 }
93 }
94 return out
95}