// test_body_contains_key.el — verifies body_contains_key correctly
// distinguishes "user asserted this field" from "user did not mention it".
// This is the gate the PATCH endpoint uses to enforce immutability.

fn body_contains_key(body: String, key: String) -> Bool {
    return str_contains(body, "\"" + key + "\":")
}

fn assert_true(name: String, got: Bool) -> Bool {
    if got {
        println("PASS " + name)
        return true
    }
    println("FAIL " + name + " want=true got=false")
    return false
}

fn assert_false(name: String, got: Bool) -> Bool {
    if got {
        println("FAIL " + name + " want=false got=true")
        return false
    }
    println("PASS " + name)
    return true
}

fn main() -> Void {
    let b1: String = "{\"post_reasoning\":\"x\"}"
    assert_true("present-non-empty", body_contains_key(b1, "post_reasoning"))

    // Empty value still counts as "asserted" — user mentioned the key.
    let b2: String = "{\"post_reasoning\":\"\"}"
    assert_true("present-empty-string", body_contains_key(b2, "post_reasoning"))

    // Key absent.
    let b3: String = "{\"gap_summary\":\"x\"}"
    assert_false("absent", body_contains_key(b3, "post_reasoning"))

    // Substring of another key must NOT match.
    // E.g. "tags":  vs "tag":  — distinct.
    let b4: String = "{\"tags\":\"a,b,c\"}"
    assert_false("substring-distinct", body_contains_key(b4, "tag"))
    assert_true("exact-tags", body_contains_key(b4, "tags"))

    // Immutable-field detection: PATCH must reject these.
    let b5: String = "{\"pre_reasoning\":\"new value\",\"post_reasoning\":\"x\"}"
    assert_true("detect-pre_reasoning", body_contains_key(b5, "pre_reasoning"))
    assert_true("detect-post_reasoning", body_contains_key(b5, "post_reasoning"))

    let b6: String = "{\"cgi_id\":\"x\"}"
    assert_true("detect-cgi_id", body_contains_key(b6, "cgi_id"))

    // No false-positive if the value happens to contain the same string.
    let b7: String = "{\"trigger\":\"contained pre_reasoning string\"}"
    assert_false("no-false-positive-from-value", body_contains_key(b7, "pre_reasoning"))
}