// Word frequency counting with a Map<String, Int> — the canonical hash-map
// histogram. Demonstrates: map bracket read/write, the ?? null-coalescing
// guard for first-seen keys, .has / .get / .set on a memory slot, and finding
// the most frequent word.
//
//   soma run  examples/corpus/algorithms/word_count.cell count "the cat sat on the mat the cat"
//   soma test examples/corpus/algorithms/word_count.cell

cell WordCount {
    face {
        signal count(text: String) -> Map
        signal most_common(text: String) -> String
        signal distinct_words(text: String) -> Int
    }

    on count(text: String) {
        let counts = map()
        for w in split(trim(text), " ") {
            if w != "" {
                counts[w] = (counts[w] ?? 0) + 1
            }
        }
        return counts
    }

    on most_common(text: String) {
        let counts = count(text)
        let best = ""
        let best_n = 0
        for w in counts.keys {
            if counts[w] > best_n {
                best_n = counts[w]
                best = w
            }
        }
        return best
    }

    on distinct_words(text: String) {
        return len(count(text).keys)
    }
}

cell test WordCountTests {
    rules {
        assert count("the cat sat on the mat the cat")["the"] == 3
        assert count("the cat sat on the mat the cat")["cat"] == 2
        assert count("the cat sat on the mat the cat")["mat"] == 1
        assert most_common("the cat sat on the mat the cat") == "the"
        assert distinct_words("a b c a b a") == 3
        assert distinct_words("") == 0
    }
}