///|
/// 配置对象的 JSON 序列化 / 反序列化，用于 CLI 与脚本持久化水印参数。
///
/// 注意：`seed`（Int64）与 `color`（Int）在 JSON 中表示为 Number；
/// Int64 超过 2^53 时会丢失精度（水印种子常规取值远小于该值，可忽略）。

///|
fn text_cfg_to_json(cfg : TextConfig) -> Json {
  Json::object(
    Map([
      ("text", Json::string(cfg.text)),
      ("x", Json::number(cfg.x.to_double())),
      ("y", Json::number(cfg.y.to_double())),
      ("font_size", Json::number(cfg.font_size.to_double())),
      ("opacity", Json::number(cfg.opacity)),
      ("angle", Json::number(cfg.angle)),
      ("color", Json::number(cfg.color.to_double())),
    ]),
  )
}

///|
/// 将 `TextConfig` 序列化为 JSON 字符串。
pub fn text_config_to_json(cfg : TextConfig) -> String {
  Json::stringify(text_cfg_to_json(cfg))
}

///|
/// 从 JSON 字符串解析 `TextConfig`；字段缺失或格式错误返回 `None`。
pub fn text_config_from_json(s : String) -> Option[TextConfig] {
  try {
    text_cfg_from_obj(@json.parse(s))
  } catch {
    _ => None
  }
}

///|
fn text_cfg_from_obj(j : Json) -> Option[TextConfig] {
  match j {
    Object(m) => {
      match (j_str(m, "text"), j_int(m, "x"), j_int(m, "y"), j_int(m, "font_size"), j_dbl(m, "opacity"), j_dbl(m, "angle"), j_int(m, "color")) {
        (Some(text), Some(x), Some(y), Some(font_size), Some(opacity), Some(angle), Some(color)) =>
          Some(
            {
              text: text,
              x: x,
              y: y,
              font_size: font_size,
              opacity: opacity,
              angle: angle,
              color: color,
            },
          )
        _ => None
      }
    }
    _ => None
  }
}

///|
/// 将 `DotConfig` 序列化为 JSON 字符串。
pub fn dot_config_to_json(cfg : DotConfig) -> String {
  Json::stringify(
    Json::object(
      Map([
        ("density", Json::number(cfg.density)),
        ("dot_size", Json::number(cfg.dot_size.to_double())),
        ("seed", Json::number(cfg.seed.to_double())),
        ("opacity", Json::number(cfg.opacity)),
        ("grid_offset_x", Json::number(cfg.grid_offset_x.to_double())),
        ("grid_offset_y", Json::number(cfg.grid_offset_y.to_double())),
      ]),
    ),
  )
}

///|
/// 从 JSON 字符串解析 `DotConfig`；字段缺失或格式错误返回 `None`。
pub fn dot_config_from_json(s : String) -> Option[DotConfig] {
  try {
    dot_cfg_from_obj(@json.parse(s))
  } catch {
    _ => None
  }
}

///|
fn dot_cfg_from_obj(j : Json) -> Option[DotConfig] {
  match j {
    Object(m) => {
      match (j_dbl(m, "density"), j_int(m, "dot_size"), j_i64(m, "seed"), j_dbl(m, "opacity"), j_int(m, "grid_offset_x"), j_int(m, "grid_offset_y")) {
        (Some(density), Some(dot_size), Some(seed), Some(opacity), Some(grid_offset_x), Some(grid_offset_y)) =>
          Some(
            {
              density: density,
              dot_size: dot_size,
              seed: seed,
              opacity: opacity,
              grid_offset_x: grid_offset_x,
              grid_offset_y: grid_offset_y,
            },
          )
        _ => None
      }
    }
    _ => None
  }
}

///|
/// 将 `TiledConfig` 序列化为 JSON 字符串。
pub fn tiled_config_to_json(cfg : TiledConfig) -> String {
  Json::stringify(
    Json::object(
      Map([
        ("text", Json::string(cfg.text)),
        ("font_size", Json::number(cfg.font_size.to_double())),
        ("spacing_x", Json::number(cfg.spacing_x.to_double())),
        ("spacing_y", Json::number(cfg.spacing_y.to_double())),
        ("opacity", Json::number(cfg.opacity)),
        ("color", Json::number(cfg.color.to_double())),
      ]),
    ),
  )
}

///|
/// 从 JSON 字符串解析 `TiledConfig`；字段缺失或格式错误返回 `None`。
pub fn tiled_config_from_json(s : String) -> Option[TiledConfig] {
  try {
    tiled_cfg_from_obj(@json.parse(s))
  } catch {
    _ => None
  }
}

///|
fn tiled_cfg_from_obj(j : Json) -> Option[TiledConfig] {
  match j {
    Object(m) => {
      match (j_str(m, "text"), j_int(m, "font_size"), j_int(m, "spacing_x"), j_int(m, "spacing_y"), j_dbl(m, "opacity"), j_int(m, "color")) {
        (Some(text), Some(font_size), Some(spacing_x), Some(spacing_y), Some(opacity), Some(color)) =>
          Some(
            {
              text: text,
              font_size: font_size,
              spacing_x: spacing_x,
              spacing_y: spacing_y,
              opacity: opacity,
              color: color,
            },
          )
        _ => None
      }
    }
    _ => None
  }
}

///|
fn j_str(m : Map[String, Json], k : String) -> Option[String] {
  match m.get(k) {
    Some(j) => {
      match j {
        String(sv) => Some(sv)
        _ => None
      }
    }
    _ => None
  }
}

///|
fn j_int(m : Map[String, Json], k : String) -> Option[Int] {
  match m.get(k) {
    Some(j) => {
      match j {
        Number(d, ..) => Some(d.to_int())
        _ => None
      }
    }
    _ => None
  }
}

///|
fn j_dbl(m : Map[String, Json], k : String) -> Option[Double] {
  match m.get(k) {
    Some(j) => {
      match j {
        Number(d, ..) => Some(d)
        _ => None
      }
    }
    _ => None
  }
}

///|
fn j_i64(m : Map[String, Json], k : String) -> Option[Int64] {
  match m.get(k) {
    Some(j) => {
      match j {
        Number(d, ..) => Some(d.to_int64())
        _ => None
      }
    }
    _ => None
  }
}