feat: add rest of tera features for templates

docs/templates.md

@@ -12,6 +12,12 @@ The following context objects are available inside templates:
 - `cwd: PathBuf` – current working directory
 - `config_root: PathBuf` – directory containing the `mise.toml` file or directory containing
   `.mise` directory with config file.
+- `mise_bin` - the path to the current mise executable
+- `mise_pid` - the pid of the current mise process
+- `xdg_cache_home` - the directory of XDG cache home
+- `xdg_config_home` - the directory of XDG config home
+- `xdg_data_home` - the directory of XDG data home
+- `xdg_state_home` - the directory of XDG state home
 
 As well as these functions:
 
@@ -20,6 +26,18 @@ As well as these functions:
 - `os() -> String` – return the operating system, e.g. `linux`, `macos`, `windows`
 - `os_family() -> String` – return the operating system family, e.g. `unix`, `windows`
 - `num_cpus() -> usize` – return the number of CPUs on the system
+- `error(message) -> String` - Abort execution and report error `message` to user.
+- `choice(n, alphabet)` - Generate a string of `n` with random sample with replacement
+  of `alphabet`. For example, `choice('64', HEX)` will generate a random
+  64-character lowercase hex string.
+- `datetime()` - Return local time with ISO 8601 format
+- `datetime(format)` - Return local time with `format`. Read the
+  [`chrono` library docs](https://docs.rs/chrono/latest/chrono/format/strftime/index.html)
+  for the format
+- `datetime_utc()` - Return UTC time with ISO 8601 format
+- `datetime_utc(format)` - Return UTC time with `format`. Read the
+  [`chrono` library docs](https://docs.rs/chrono/latest/chrono/format/strftime/index.html)
+  for the format
 
 And these filters:
 

src/env.rs

@@ -2,6 +2,7 @@ use std::collections::{HashMap, HashSet};
 pub use std::env::*;
 use std::path;
 use std::path::PathBuf;
+use std::process;
 use std::string::ToString;
 use std::sync::RwLock;
 use std::time::Duration;
@@ -126,6 +127,7 @@ pub static MISE_BIN: Lazy<PathBuf> = Lazy::new(|| {
         .or_else(|| current_exe().ok())
         .unwrap_or_else(|| "mise".into())
 });
+pub static MISE_PID: Lazy<String> = Lazy::new(|| process::id().to_string());
 pub static __MISE_SCRIPT: Lazy<bool> = Lazy::new(|| var_is_true("__MISE_SCRIPT"));
 pub static __MISE_DIFF: Lazy<EnvDiff> = Lazy::new(get_env_diff);
 pub static __MISE_ORIG_PATH: Lazy<Option<String>> = Lazy::new(|| var("__MISE_ORIG_PATH").ok());