// Given a blank board, find all words we can play with our given tiles, from the center.
//
// Since the center spot is always required, we just always start our words
// from there. No word will ever be long enough to go off the edge of the
// board, since that is 8 tiles away and we only ever have 7.
//
// Also, direction is not important because the board has 4-way symmetry. So,
// we always choose 7,7,RIGHT.
func InitialWords(idx index.Index, available map[byte]int) <-chan foundword {
allowed := index.NewUnanchoredAllowedInfo(
[]string{".", ".", ".", ".", ".", ".", "."},
[]bool{true, true, true, true, true, true, true},
available)
out := make(chan foundword)
go func() {
defer close(out)
for left := 0; left < 7; left++ {
subinfo := allowed.MakeSuffix(left)
for seq := range idx.ConstrainedSequences(subinfo) {
out <- foundword{
word: string(seq),
start: 7,
line: 7,
direction: RIGHT,
}
}
}
}()
return out
}
// Given a line-oriented query (find me a word that matches this sort of line),
// produce all valid words on that line.
func LineWords(line, direction int, idx index.Index, lineQuery []string, available map[byte]int) <-chan foundword {
allowed := idx.GetAllowedLetters(lineQuery, available)
out := make(chan foundword)
go func() {
defer close(out)
for left := range GetSubSuffixes(allowed) {
subinfo := allowed.MakeSuffix(left)
if !subinfo.PossiblePrefix() {
continue
}
for seq := range idx.ConstrainedSequences(subinfo) {
out <- foundword{
word: string(seq),
start: left,
line: line,
direction: direction,
}
}
}
}()
return out
}