pipa-lang 1.0.0-alpha.1

A tiny template language
Documentation 
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// SPDX-FileCopyrightText: Copyright 2026 olav@occy.org
// SPDX-License-Identifier: MPL-2.0

use crate::lang::adapter::Adapter;
use crate::lang::args::arg_into_string;
use crate::lang::args::eval_args;
use crate::lang::arity::Arity;
use crate::lang::arity::assert_func_arity;
use crate::lang::error::Error;
use crate::lang::error::ErrorKind;
use crate::lang::machine::Machine;
use crate::lang::node::Node;
use crate::value::Value;
use jiff::Timestamp;
use jiff::Zoned;
use jiff::civil::Date;
use jiff::civil::DateTime;
use jiff::civil::Time;
use jiff::tz::TimeZone;
use std::sync::LazyLock;

static ZONE: LazyLock<TimeZone> = LazyLock::new(TimeZone::system);

pub(crate) fn format_date(
    adapter: &impl Adapter,
    machine: &mut Machine<'_>,
    stdin: Option<&Value>,
    node: Node,
) -> Result<Value, Error> {
    assert_func_arity(adapter, machine, stdin, &node, &Arity::minmax(1, 2))?;

    let mut node = eval_args(adapter, machine, stdin, node)?;
    let strf = node.swap_remove(0).unwrap_or_default().join();
    let date = arg_into_string(node.pop().flatten());

    let value = date.as_ref().map(|v| parse(adapter, machine, v));
    let value = value.transpose()?;
    let value = value.unwrap_or_else(zoned);
    let value = value.strftime(&strf).to_string();

    Ok(value.into())
}

fn parse(adapter: &impl Adapter, machine: &Machine<'_>, value: &str) -> Result<Zoned, Error> {
    let err = |_| date_error(adapter, machine, value);

    if let Ok(v) = value.parse::<Timestamp>() {
        return Ok(v.to_zoned(zone()));
    }

    if let Ok(v) = value.parse::<DateTime>() {
        return v.to_zoned(zone()).map_err(err);
    }

    if let Ok(v) = value.parse::<Date>() {
        return v.to_zoned(zone()).map_err(err);
    }

    if let Ok(v) = value.parse::<Time>() {
        return v
            .to_datetime(date())
            .in_tz(ZONE.iana_name().unwrap_or("unknown"))
            .map_err(err);
    }

    Err(date_error(adapter, machine, value))
}

fn date_error(adapter: &impl Adapter, machine: &Machine<'_>, value: &str) -> Error {
    Error {
        kind: ErrorKind::Func,
        source: adapter.template_source().map(String::from),
        span: machine.span,
        message: format!("unknown date format: {value}"),
    }
}

fn date() -> Date {
    Timestamp::now().to_zoned(zone()).into()
}

fn zoned() -> Zoned {
    Timestamp::now().to_zoned(zone())
}

fn zone() -> TimeZone {
    ZONE.clone()
}