package sbt.complete
import java.lang.Character.{toLowerCase => lower}
object EditDistance {
def levenshtein(s: String, t: String, insertCost: Int = 1, deleteCost: Int = 1, subCost: Int = 1, transposeCost: Int = 1, matchCost: Int = 0, caseCost: Int = 1, transpositions: Boolean = false): Int = {
val n = s.length
val m = t.length
if (n == 0) return m
if (m == 0) return n
val d = Array.ofDim[Int](n + 1, m + 1)
0 to n foreach (x => d(x)(0) = x)
0 to m foreach (x => d(0)(x) = x)
for (i <- 1 to n ; val s_i = s(i - 1) ; j <- 1 to m) {
val t_j = t(j - 1)
val cost = if (s_i == t_j) matchCost else if(lower(s_i) == lower(t_j)) caseCost else subCost
val tcost = if (s_i == t_j) matchCost else transposeCost
val c1 = d(i - 1)(j) + deleteCost
val c2 = d(i)(j - 1) + insertCost
val c3 = d(i - 1)(j - 1) + cost
d(i)(j) = c1 min c2 min c3
if (transpositions) {
if (i > 1 && j > 1 && s(i - 1) == t(j - 2) && s(i - 2) == t(j - 1))
d(i)(j) = d(i)(j) min (d(i - 2)(j - 2) + cost)
}
}
d(n)(m)
}
}