//! JSON ↔ Rhai `Dynamic` value bridge.
//!
//! Originally inline in `engine.rs`; moved here for v1.1.0 so future
//! service modules (KV in v1.1.1, docs in v1.1.2, …) can convert
//! values without `engine.rs` being the only owner of the conversions.
//! Behaviour is unchanged from the pre-extraction implementation —
//! `sdk_contract.rs::json_round_trip_preserves_nested_shapes` pins the
//! observable round-trip.

use rhai::{Dynamic, Map};
use serde_json::Value as Json;

/// Convert a `serde_json::Value` into a Rhai `Dynamic` suitable for
/// pushing into a script's scope. Numbers prefer the narrowest type
/// (`i64` over `f64`); anything that can't round-trip falls back to a
/// string so the script always sees a defined value.
pub fn json_to_dynamic(value: Json) -> Dynamic {
    match value {
        Json::Null => Dynamic::UNIT,
        Json::Bool(b) => b.into(),
        Json::Number(n) => {
            if let Some(i) = n.as_i64() {
                i.into()
            } else if let Some(f) = n.as_f64() {
                f.into()
            } else {
                n.to_string().into()
            }
        }
        Json::String(s) => s.into(),
        Json::Array(arr) => arr
            .into_iter()
            .map(json_to_dynamic)
            .collect::<Vec<Dynamic>>()
            .into(),
        Json::Object(obj) => {
            let mut m = Map::new();
            for (k, v) in obj {
                m.insert(k.into(), json_to_dynamic(v));
            }
            Dynamic::from(m)
        }
    }
}

/// Convert a Rhai `Dynamic` back to a `serde_json::Value`. Custom Rhai
/// types (timestamps, user-registered modules) fall back to their
/// `Display` form so they appear as strings in JSON output rather than
/// failing the response build.
pub fn dynamic_to_json(value: &Dynamic) -> Json {
    if value.is_unit() {
        return Json::Null;
    }
    if let Ok(b) = value.as_bool() {
        return Json::Bool(b);
    }
    if let Ok(i) = value.as_int() {
        return Json::Number(i.into());
    }
    if let Ok(f) = value.as_float() {
        return serde_json::Number::from_f64(f).map_or(Json::Null, Json::Number);
    }
    if value.is_string() {
        return Json::String(value.clone().into_string().unwrap_or_default());
    }
    if let Some(arr) = value.clone().try_cast::<rhai::Array>() {
        return Json::Array(arr.iter().map(dynamic_to_json).collect());
    }
    if let Some(map) = value.clone().try_cast::<Map>() {
        let mut out = serde_json::Map::new();
        for (k, v) in map {
            out.insert(k.to_string(), dynamic_to_json(&v));
        }
        return Json::Object(out);
    }
    Json::String(value.to_string())
}