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package viewport
import (
"strings"
)
const Caret = "⏵"
func NeedsViewport(input string, height int) bool {
lines := strings.Split(input, "\n")
return len(lines)-1 > height
}
func Process(input string, height int) string {
lines := strings.Split(input, "\n")
if len(lines) > height {
cropped, top, bottom := Crop(input, lines, height)
return WithScroll(cropped, int(top*float32(height)), int(bottom*float32(height)))
}
return input
}
func Focus(lines []string, needle string) int {
for i, l := range lines {
if strings.Contains(l, needle) {
return i
}
}
return -1
}
func Crop(input string, lines []string, height int) (output string, scrollStart float32, scrollEnd float32) {
output = input
selectionIndex := Focus(lines, Caret)
size := len(lines)
if size <= height {
return output, 0, 1
}
linesAbove := height / 2
linesBelow := height - linesAbove
if linesAbove*2 < selectionIndex {
linesBelow++
}
start := selectionIndex - linesAbove
end := selectionIndex + linesBelow
if start < 0 {
end += -start
start = 0
}
if end >= size {
diff := size - 1 - end
start += diff
end += diff
}
scrollStart = float32(start) / float32(size)
scrollEnd = float32(end)/float32(size) + float32(1)/float32(size)
if scrollEnd > 1 {
scrollEnd = 1
}
return strings.Join(lines[start:end], "\n"), scrollStart, scrollEnd
}
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