//! Where Onset keeps things on this machine, and its environment variables.

use std::ffi::OsString;
use std::path::PathBuf;

/// `ONSET_<name>`, or `VCS_<name>` as it was called before Onset had its name (empty counts as unset).
pub fn var_os(name: &str) -> Option<OsString> {
    let set = |v: String| std::env::var_os(v).filter(|v| !v.is_empty());
    set(format!("ONSET_{name}")).or_else(|| set(format!("VCS_{name}")))
}

/// [`var_os`] as text.
pub fn var(name: &str) -> Option<String> {
    var_os(name).and_then(|v| v.into_string().ok())
}

/// ONSET_HOME, else the platform's data folder (~/.local/share/onset on
/// Linux, ~/Library/Application Support/onset on macOS, %LOCALAPPDATA%\onset
/// on Windows). A machine that used it as vcs keeps its folder of that name.
pub fn home() -> PathBuf {
    if let Some(dir) = var_os("HOME") {
        return PathBuf::from(dir);
    }
    let data = if cfg!(windows)
        && let Some(local) = std::env::var_os("LOCALAPPDATA").filter(|d| !d.is_empty())
    {
        PathBuf::from(local)
    } else {
        let user = crate::sys::user_home().unwrap_or_else(|| ".".into());
        if cfg!(target_os = "macos") {
            user.join("Library/Application Support")
        } else {
            match std::env::var_os("XDG_DATA_HOME") {
                Some(d) if !d.is_empty() => PathBuf::from(d),
                _ => user.join(".local/share"),
            }
        }
    };
    let (new, old) = (data.join("onset"), data.join("vcs"));
    if !new.exists() && old.join("vcs.db").exists() { old } else { new }
}

pub fn objects() -> PathBuf {
    home().join("objects")
}

/// Sign-in tokens, readable only by the user.
pub fn credentials() -> PathBuf {
    home().join("credentials.json")
}