mod color;
mod gif;
mod lzw;

pub mod block;
pub mod reader;
pub mod writer;

use core::fmt;
use std::error::Error;

pub use color::Color;
pub use gif::Gif;
pub use lzw::LZW;

/// Perform the algorithm to get the length of a color table from
/// the value of the packed field. The max value here is 256
pub(crate) fn packed_to_color_table_length(packed: u8) -> usize {
    2usize.pow(packed as u32 + 1)
}

//TODO: Be sure to check that fields in LSD and Img. Desc. that were reserved
//in 87a aren't set if version is 87a, or that we return a warning, etc. Just
//remember about this.
//bottom of page 24 in 89a

#[derive(Clone, Copy, Debug)]
pub enum EncodingError {
    TooManyColors,
    NoColorTable,
    IndicieSizeMismatch { expected: usize, got: usize },
}

impl fmt::Display for EncodingError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::TooManyColors => write!(f, "A palette is limited to 256 colors"),
            Self::NoColorTable => write!(
                f,
                "Refusing to set the background color index when no color table is set!"
            ),
            Self::IndicieSizeMismatch { expected, got } => {
                write!(f, "Expected to have {} indicies but got {}", expected, got)
            }
        }
    }
}

impl Error for EncodingError {}