use anyhow::{Context, Result};
use serde::{de::DeserializeOwned, Serialize};
use serde_yaml::{Mapping, Value};
use std::{fs, path::PathBuf};

/// read data from yaml as struct T
pub fn read_yaml<T: DeserializeOwned + Default>(path: PathBuf) -> T {
  if !path.exists() {
    log::error!(target: "app", "file not found \"{}\"", path.display());
    return T::default();
  }

  let yaml_str = fs::read_to_string(&path).unwrap_or("".into());

  match serde_yaml::from_str::<T>(&yaml_str) {
    Ok(val) => val,
    Err(_) => {
      log::error!(target: "app", "failed to read yaml file \"{}\"", path.display());
      T::default()
    }
  }
}

/// read mapping from yaml fix #165
pub fn read_merge_mapping(path: PathBuf) -> Mapping {
  let map = Mapping::new();

  if !path.exists() {
    log::error!(target: "app", "file not found \"{}\"", path.display());
    return map;
  }

  let yaml_str = fs::read_to_string(&path).unwrap_or("".into());

  match serde_yaml::from_str::<Value>(&yaml_str) {
    Ok(mut val) => {
      crate::log_if_err!(val.apply_merge());
      val.as_mapping().unwrap_or(&map).to_owned()
    }
    Err(_) => {
      log::error!(target: "app", "failed to read yaml file \"{}\"", path.display());
      map
    }
  }
}

/// save the data to the file
/// can set `prefix` string to add some comments
pub fn save_yaml<T: Serialize>(path: PathBuf, data: &T, prefix: Option<&str>) -> Result<()> {
  let data_str = serde_yaml::to_string(data)?;

  let yaml_str = match prefix {
    Some(prefix) => format!("{prefix}{data_str}"),
    None => data_str,
  };

  let path_str = path.as_os_str().to_string_lossy().to_string();
  fs::write(path, yaml_str.as_bytes()).context(format!("failed to save file \"{path_str}\""))
}