// ============================================================================
// Title case — capitalize the first letter of every word
// ============================================================================
//
// Splits on spaces, uppercases each word's first character and lowercases the
// rest, then re-joins. Demonstrates substring slicing and per-word transforms
// mapped over the word list.
//
// Run: soma run title_case.cell --signal titlecase "the QUICK brown fox"

cell TitleCase {
    face {
        signal capitalize(word: String) -> String
        signal titlecase(text: String) -> String
    }

    on capitalize(word: String) {
        if len(word) == 0 { return "" }
        let head = uppercase(substring(word, 0, 1))
        let tail = lowercase(substring(word, 1, len(word)))
        return head + tail
    }

    on titlecase(text: String) {
        let words = split(text, " ")
        let out = words |> map(w => capitalize(w))
        return join(out, " ")
    }
}

cell test TitleCaseTest {
    rules {
        assert capitalize("hello") == "Hello"
        assert capitalize("WORLD") == "World"
        assert capitalize("a") == "A"
        assert titlecase("the quick brown fox") == "The Quick Brown Fox"
        assert titlecase("MIXED case INPUT") == "Mixed Case Input"
    }
}