// ============================================================================
// Reverse word order — "hello world" -> "world hello"
// ============================================================================
//
// Splits on spaces, reverses the resulting list, and re-joins. Also offers a
// per-word character reversal that keeps word positions. Demonstrates the
// difference between reversing the word list vs. reversing each word.
//
// Run: soma run reverse_words.cell --signal reverse_order "the quick brown fox"

cell ReverseWords {
    face {
        signal reverse_order(text: String) -> String
        signal reverse_each(text: String) -> String
    }

    on reverse_order(text: String) {
        let words = split(text, " ")
        return join(words.reverse(), " ")
    }

    on _flip(w: String) {
        let out = ""
        for i in range(len(w) - 1, -1, -1) {
            out = out + w[i]
        }
        return out
    }

    on reverse_each(text: String) {
        let words = split(text, " ")
        let flipped = words |> map(w => _flip(w))
        return join(flipped, " ")
    }
}

cell test ReverseWordsTest {
    rules {
        assert reverse_order("hello world") == "world hello"
        assert reverse_order("a b c d") == "d c b a"
        assert reverse_each("hello world") == "olleh dlrow"
        assert reverse_each("abc") == "cba"
        assert reverse_order("single") == "single"
    }
}