use crate::host_bridge::protocol::{HOST_BRIDGE_PROTOCOL, HOST_BRIDGE_VERSION};
use serde_json::{json, Value};

const HOST_BRIDGE_EVENTS: [&str; 3] = [
    "app.lifecycle",
    "navigation.canGoBack",
    "file.imageDropped",
];

fn is_host_bridge_event_name(event: &str) -> bool {
    HOST_BRIDGE_EVENTS.contains(&event)
}

pub(crate) fn host_bridge_event_script(
    event: &str,
    payload: Value,
) -> Result<String, serde_json::Error> {
    if !is_host_bridge_event_name(event) {
        return Err(serde_json::Error::io(std::io::Error::new(
            std::io::ErrorKind::InvalidInput,
            format!("unknown HostBridge event: {}", event),
        )));
    }

    let message = json!({
        "bridge": HOST_BRIDGE_PROTOCOL,
        "version": HOST_BRIDGE_VERSION,
        "event": event,
        "payload": payload,
    });
    let data = serde_json::to_string(&message)?;
    let data_literal = serde_json::to_string(&data)?;

    Ok(format!(
        "window.dispatchEvent(new MessageEvent('message', {{ data: {}, origin: window.location.origin, source: window }})); true;",
        data_literal
    ))
}

#[cfg(test)]
mod tests {
    use super::*;
    use serde_json::json;

    #[test]
    fn host_bridge_event_script_dispatches_lifecycle_message() {
        let script = host_bridge_event_script(
            "app.lifecycle",
            json!({
                "state": "active",
                "focused": true,
                "nativeState": "focused",
            }),
        )
        .expect("event script");

        assert!(script.contains("MessageEvent('message'"));
        assert!(script.contains("origin: window.location.origin"));
        assert!(script.contains("source: window"));
        assert!(script.contains("GenarrativeHostBridge"));
        assert!(script.contains("app.lifecycle"));
        assert!(script.contains("\\\"state\\\":\\\"active\\\""));
        assert!(script.contains("\\\"focused\\\":true"));
    }

    #[test]
    fn host_bridge_event_script_rejects_unknown_events() {
        let error =
            host_bridge_event_script("unknown.event", json!({})).expect_err("unknown event");

        assert!(error.to_string().contains("unknown HostBridge event"));
    }
}