//! Support module for writing `key=value` stores.
//!
//! These files are used by minetest mods (`mod.conf`), games (`game.conf`) and worlds
//! (`world.mt`).
//!
//! Key-Value-Stores (KVStores) are represented by a [`std::collections::HashMap`] on the Rust
//! side.
use std::{collections::HashMap, fs, io::Write, path::Path};

use super::error::Result;

/// Read the given file as a KVStore.
pub fn read<P: AsRef<Path>>(path: P) -> Result<HashMap<String, String>> {
    read_inner(path.as_ref())
}

fn read_inner(path: &Path) -> Result<HashMap<String, String>> {
    let content = fs::read_to_string(path)?;

    Ok(content
        .lines()
        .map(|line| line.splitn(2, '=').map(str::trim).collect::<Vec<_>>())
        .map(|v| (v[0].into(), v[1].into()))
        .collect())
}

/// Write the given KVStore back to the file.
///
/// The order of the keys is guaranteed to be the following:
///
/// 1. All options that *don't* start with `"load_mod_"` are saved in alphabetical order.
/// 2. All remaining options are saved in alphabetical order.
///
/// Note that this function will **override** existing files!
pub fn write<P: AsRef<Path>>(data: &HashMap<String, String>, path: P) -> Result<()> {
    write_inner(data, path.as_ref())
}

fn write_inner(data: &HashMap<String, String>, path: &Path) -> Result<()> {
    let mut items = data.iter().collect::<Vec<_>>();
    items.sort_by_key(|i| (if i.0.starts_with("load_mod_") { 1 } else { 0 }, i.0));

    let mut output = fs::File::create(path)?;
    for (key, value) in items {
        writeln!(output, "{} = {}", key, value)?;
    }

    Ok(())
}