lib-q-core 0.0.4

//! WASM utility functions
//!
//! This module provides utility functions specifically designed for WASM environments,
//! including secure random generation, data validation, and helper functions.

#[cfg(feature = "wasm")]
use js_sys::Uint8Array;
#[cfg(feature = "wasm")]
use serde_json;
#[cfg(feature = "wasm")]
use wasm_bindgen::prelude::*;

#[cfg(feature = "wasm")]
extern crate alloc;
#[cfg(feature = "wasm")]
use alloc::{
    collections::BTreeMap,
    format,
    string::{
        String,
        ToString,
    },
    vec::Vec,
};

#[cfg(feature = "wasm")]
use crate::wasm::conversions::WASM_SIGNATURE_ALGORITHM_IDS;

/// Generate cryptographically secure random bytes for WASM
///
/// This function provides secure random generation in WASM environments:
/// - Uses the browser's crypto.getRandomValues() API
/// - Validates input size to prevent DoS attacks
/// - Returns Uint8Array for direct JavaScript consumption
#[cfg(feature = "wasm")]
#[wasm_bindgen]
pub fn random_bytes(length: usize) -> Result<Uint8Array, String> {
    if length == 0 {
        return Err("Invalid length: 0".to_string());
    }

    const MAX_RANDOM_SIZE: usize = 1024 * 1024; // 1MB limit
    if length > MAX_RANDOM_SIZE {
        return Err(format!(
            "Length {} exceeds maximum {}",
            length, MAX_RANDOM_SIZE
        ));
    }

    // Generate secure random bytes using getrandom (which uses crypto.getRandomValues() in WASM)
    let mut bytes = alloc::vec![0u8; length];
    getrandom::fill(&mut bytes)
        .map_err(|e| format!("Failed to generate secure random bytes: {}", e))?;

    // Convert to Uint8Array for JavaScript consumption
    let array = Uint8Array::new_with_length(length as u32);
    for (i, &byte) in bytes.iter().enumerate() {
        array.set_index(i as u32, byte);
    }

    Ok(array)
}

/// Validate input data for WASM operations
///
/// This function provides comprehensive input validation:
/// - Checks for null/undefined values
/// - Validates data size limits
/// - Ensures data is not empty when required
#[cfg(feature = "wasm")]
#[wasm_bindgen]
pub fn validate_input(
    data: &Uint8Array,
    min_size: Option<usize>,
    max_size: Option<usize>,
) -> Result<bool, String> {
    let length = data.length() as usize;

    // Check minimum size
    if let Some(min) = min_size &&
        length < min
    {
        return Err(format!("Length {} is less than minimum {}", length, min));
    }

    // Check maximum size
    if let Some(max) = max_size &&
        length > max
    {
        return Err(format!("Length {} exceeds maximum {}", length, max));
    }

    Ok(true)
}

/// Convert bytes to hexadecimal string
///
/// This function provides secure hex encoding for WASM:
/// - Uses constant-time operations where possible
/// - Handles large data efficiently
/// - Returns JavaScript string
#[cfg(feature = "wasm")]
#[wasm_bindgen]
pub fn bytes_to_hex(data: &Uint8Array) -> String {
    let length = data.length() as usize;
    let mut hex = String::with_capacity(length * 2);

    for i in 0..length {
        let byte = data.get_index(i as u32);
        hex.push_str(&format!("{:02x}", byte));
    }

    hex
}

/// Convert hexadecimal string to bytes
///
/// This function provides secure hex decoding for WASM:
/// - Validates hex string format
/// - Handles errors gracefully
/// - Returns Uint8Array
#[cfg(feature = "wasm")]
#[wasm_bindgen]
pub fn hex_to_bytes(hex: &str) -> Result<Uint8Array, String> {
    if !hex.len().is_multiple_of(2) {
        return Err("Invalid hex string length".to_string());
    }

    let length = hex.len() / 2;
    let array = Uint8Array::new_with_length(length as u32);

    for (i, chunk) in hex.as_bytes().chunks(2).enumerate() {
        let hex_str = core::str::from_utf8(chunk).map_err(|_| "Invalid hex character")?;

        let byte = u8::from_str_radix(hex_str, 16).map_err(|_| "Invalid hex character")?;

        array.set_index(i as u32, byte);
    }

    Ok(array)
}

/// Get library information for WASM
///
/// This function provides library metadata for JavaScript consumption
#[cfg(feature = "wasm")]
#[wasm_bindgen]
pub fn get_library_info() -> String {
    serde_json::json!({
        "name": "lib-Q",
        "version": crate::VERSION,
        "description": "Post-Quantum Cryptography Library",
        "features": {
            "wasm": true,
            "security_hardened": true,
            "post_quantum": true
        }
    })
    .to_string()
}

/// Check if a feature is available
///
/// This function allows JavaScript to check feature availability
#[cfg(feature = "wasm")]
#[wasm_bindgen]
pub fn is_feature_available(feature: &str) -> bool {
    #[allow(clippy::match_like_matches_macro)]
    match feature {
        "ml-kem" => cfg!(feature = "ml-kem"),
        "ml-dsa" => cfg!(feature = "ml-dsa"),
        "fn-dsa" => cfg!(feature = "fn-dsa"),
        "slh-dsa" => cfg!(feature = "slh-dsa"),
        "saturnin" => cfg!(feature = "saturnin"),
        "hash" => cfg!(feature = "hash"),
        "wasm" => true,
        _ => false,
    }
}

/// Get supported algorithms by category
///
/// This function provides algorithm information for JavaScript
#[cfg(feature = "wasm")]
#[wasm_bindgen]
pub fn get_supported_algorithms() -> String {
    // use crate::api::AlgorithmCategory;

    let mut algorithms = BTreeMap::new();

    // KEM algorithms
    let mut kem_algorithms = Vec::new();
    kem_algorithms.extend(&["ml-kem-512", "ml-kem-768", "ml-kem-1024"]);
    algorithms.insert("kem", kem_algorithms);

    // Signature algorithms (single source: `conversions::WASM_SIGNATURE_ALGORITHM_IDS`)
    algorithms.insert("signature", WASM_SIGNATURE_ALGORITHM_IDS.to_vec());

    // Hash algorithms
    let hash_algorithms = alloc::vec![
        "sha3-224", "sha3-256", "sha3-384", "sha3-512", "shake128", "shake256",
    ];
    algorithms.insert("hash", hash_algorithms);

    // AEAD algorithms
    let mut aead_algorithms = Vec::new();
    aead_algorithms.extend(&["saturnin", "shake256-aead"]);
    algorithms.insert("aead", aead_algorithms);

    serde_json::to_string(&algorithms).unwrap_or_else(|_| "{}".to_string())
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_feature_availability() {
        // Test that feature checking works
        assert!(is_feature_available("wasm"));
        // Other features depend on actual feature flags
    }

    #[test]
    fn test_library_info() {
        let info = get_library_info();
        assert!(info.contains("lib-Q"));
        assert!(info.contains("version"));
    }

    #[test]
    fn test_supported_algorithms() {
        let algorithms = get_supported_algorithms();
        assert!(algorithms.contains("hash"));
        assert!(algorithms.contains("sha3-256"));
    }
}