//! Helper Functions for Tuner

//!

//! Utility functions: CRC32, timestamp, string formatting.

// ============================================================================

// CRC32 Implementation

// ============================================================================

/// Generate CRC32 lookup table at compile time.

const fn crc32_table() -> [u32; 256] {

    let mut table = [0u32; 256];

    let mut i = 0;

    while i < 256 {

        let mut crc = i as u32;

        let mut j = 0;

        while j < 8 {

            if crc & 1 != 0 {

                crc = 0xEDB8_8320 ^ (crc >> 1);

            } else {

                crc >>= 1;

            }

            j += 1;

        }

        table[i] = crc;

        i += 1;

    }

    table

}

/// Simple CRC32 implementation (IEEE polynomial).

/// Used for .apr file checksum verification.

pub fn crc32_update(crc: u32, data: &[u8]) -> u32 {

    const CRC32_TABLE: [u32; 256] = crc32_table();

    let mut crc = !crc;

    for &byte in data {

        crc = CRC32_TABLE[((crc ^ u32::from(byte)) & 0xFF) as usize] ^ (crc >> 8);

    }

    !crc

}

/// Compute CRC32 hash for given data (convenience wrapper)

pub fn crc32_hash(data: &[u8]) -> u32 {

    crc32_update(0, data)

}

// ============================================================================

// Timestamp

// ============================================================================

/// Simple timestamp (avoids chrono dependency)

pub fn chrono_lite_now() -> String {

    use std::time::{SystemTime, UNIX_EPOCH};

    let duration = SystemTime::now()

        .duration_since(UNIX_EPOCH)

        .unwrap_or_default();

    format!("{}", duration.as_secs())

}

// ============================================================================

// String Formatting

// ============================================================================

/// Pad string to fixed width

pub fn pad_right(s: &str, width: usize) -> String {

    if s.len() >= width {

        s[..width].to_string()

    } else {

        format!("{}{}", s, " ".repeat(width - s.len()))

    }

}