llrt_core 0.8.1-beta

LLRT Core for rquickjs
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// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0

//! LLRT timezone module providing timezone offset calculations.

use jiff::{
    tz::{TimeZone, TimeZoneDatabase},
    Timestamp,
};
use rquickjs::{
    atom::PredefinedAtom,
    module::{Declarations, Exports, ModuleDef},
    prelude::Func,
    Array, Ctx, Exception, Object, Result,
};

use crate::libs::utils::module::{export_default, ModuleInfo};

/// Get the UTC offset in minutes for a timezone at a given epoch milliseconds.
/// Returns a positive value for timezones ahead of UTC (e.g., +60 for UTC+1)
/// and a negative value for timezones behind UTC (e.g., -420 for UTC-7).
fn get_offset(ctx: Ctx<'_>, timezone: String, epoch_ms: f64) -> Result<i32> {
    let tz = TimeZone::get(timezone.as_str())
        .map_err(|_| Exception::throw_type(&ctx, &format!("Invalid timezone: {}", timezone)))?;

    let naive = Timestamp::from_millisecond(epoch_ms as i64).map_err(|_| {
        Exception::throw_range(&ctx, &format!("Invalid epoch milliseconds: {}", epoch_ms))
    })?;

    let offset = tz.to_offset(naive).seconds();

    // Return offset in minutes (positive = ahead of UTC, negative = behind)
    Ok(offset / 60)
}

/// List all available IANA timezone names.
fn list_timezones(ctx: Ctx<'_>) -> Result<Array<'_>> {
    let timezones = TimeZoneDatabase::from_env();
    let array = Array::new(ctx.clone())?;

    for (i, tz) in timezones.available().enumerate() {
        array.set(i, tz.as_str())?;
    }

    Ok(array)
}

fn timezone_object<'js>(ctx: &Ctx<'js>) -> Result<Object<'js>> {
    let timezone = Object::new(ctx.clone())?;

    timezone.set("getOffset", Func::from(get_offset))?;
    timezone.set("list", Func::from(list_timezones))?;
    timezone.set(PredefinedAtom::SymbolToStringTag, "Timezone")?;

    Ok(timezone)
}

pub struct LlrtTimezoneModule;

impl ModuleDef for LlrtTimezoneModule {
    fn declare(decl: &Declarations) -> Result<()> {
        decl.declare("Timezone")?;
        decl.declare("default")?;
        Ok(())
    }

    fn evaluate<'js>(ctx: &Ctx<'js>, exports: &Exports<'js>) -> Result<()> {
        let timezone = timezone_object(ctx)?;
        export_default(ctx, exports, |default| {
            default.set("Timezone", timezone.clone())?;
            Ok(())
        })?;
        exports.export("Timezone", timezone)?;
        Ok(())
    }
}

impl From<LlrtTimezoneModule> for ModuleInfo<LlrtTimezoneModule> {
    fn from(val: LlrtTimezoneModule) -> Self {
        ModuleInfo {
            name: "llrt:timezone",
            module: val,
        }
    }
}