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/// Macro to generate a function that retrieves a field value from a JSON file.
///
/// # Arguments
///
/// * `$func_name` - The name of the generated function.
/// * `$deserializer` - The deserializer used to parse the JSON file.
///
/// # Returns
///
/// The generated function returns a `Result` containing the field value as a `String`,
/// or a `Box<dyn std::error::Error>` if an error occurs.
///
#[macro_export]
macro_rules! macro_get_field {
    ($func_name:ident, $deserializer:expr) => {
        /// Reads a file and deserializes its content using the specified
        /// deserializer function.
        pub fn $func_name(
            // The path of the JSON file to read.
            file_path: Option<&str>,
            // The name of the field to retrieve.
            field_name: &str,
        ) -> Result<String, Box<dyn std::error::Error>> {
            file_path.map_or_else(
                || Ok(String::new()),
                |file_path| {
                    let current_dir = env::current_dir()?;
                    let file_path =
                        Path::new(&current_dir).join(file_path);
                    let file_contents =
                        std::fs::read_to_string(&file_path)?;
                    let value: serde_json::Value =
                        $deserializer(file_contents.as_bytes())?;
                    let field_value = value
                        .get(field_name)
                        .ok_or_else(|| {
                            format!("Field '{}' not found", field_name)
                        })?
                        .as_str()
                        .map(|s| s.to_string())
                        .unwrap_or_else(|| {
                            value[field_name].to_string()
                        });
                    Ok(field_value)
                },
            )
        }
    };
}