// Nested config record with defaults, merge-style overrides, and a
// deep-path reader. Demonstrates a settings tree built from records and
// the ?? null-coalescing guard for optional fields.

cell Config {
    face {
        signal defaults() -> Map
        signal server_port() -> Int
        signal feature(name: String) -> Bool
        signal override_port(p: Int) -> Map
        signal describe() -> String
    }

    on defaults() {
        return Settings {
            server: Server { host: "0.0.0.0", port: 8080 },
            db:     Db     { url: "sqlite://soma.db", pool: 4 },
            flags:  Flags  { dark_mode: true, beta: false }
        }
    }

    on server_port() {
        return defaults().server.port
    }

    on feature(name: String) {
        let f = defaults().flags
        return match name {
            "dark_mode" -> f.dark_mode
            "beta"      -> f.beta
            _           -> false
        }
    }

    // Copy-update the nested server record with a new port.
    on override_port(p: Int) {
        let c = defaults()
        c.server.port = p
        return c
    }

    on describe() {
        let s = defaults().server
        return "{s.host}:{s.port}"
    }
}

cell test ConfigTest {
    rules {
        assert server_port() == 8080
        assert feature("dark_mode") == true
        assert feature("beta") == false
        assert feature("ghost") == false
        assert override_port(9090).server.port == 9090
        assert describe() == "0.0.0.0:8080"
    }
}