use arrayvec::{ArrayString, ArrayVec};
use png::{BitDepth, ColorType, EncodingError};
use std::fs::File;
use std::io::{BufRead, BufReader, BufWriter, Lines};
use std::{env, io, process};
use thiserror::Error;

mod nummap;

#[cfg(test)]
mod test;

#[derive(Error, Debug)]
#[allow(clippy::enum_variant_names)]
enum CifError {
    #[error("The CIF number string was too long")]
    CapacityError,
    #[error("CIF Number is invalid: {0:?}")]
    GrammarError(String),
    #[error("An IO error has occurred: {0}")]
    IoError(io::Error),
    #[error("CIF header is invalid")]
    InvalidHeaderError,
    #[error("CIF size is invalid: {0:?}")]
    InvalidSizeError(String),
    #[error("CIF metadata corrupted: {0:?}")]
    InvalidMetadataError(String),
    #[error("Invalid CIF pixel: {0}")]
    InvalidPixelError(String),
    #[error("CIF image doesn't contain any pixels")]
    NoDataError,
    #[error("PNG error: {0}")]
    PngError(EncodingError),
    #[error("Illegal whitespace: {0:?}")]
    IllegalWhitespaceError(String),
}

#[allow(clippy::enum_glob_use)]
use crate::CifError::*;

impl<T> From<arrayvec::CapacityError<T>> for CifError {
    fn from(_: arrayvec::CapacityError<T>) -> Self {
        CapacityError
    }
}

impl From<io::Error> for CifError {
    fn from(e: io::Error) -> Self {
        IoError(e)
    }
}

impl From<EncodingError> for CifError {
    fn from(e: EncodingError) -> Self {
        PngError(e)
    }
}

type Result<T> = std::result::Result<T, CifError>;

fn join_to_arraystring<const C: usize>(elems: &[&str], str: &mut ArrayString<C>) -> Result<()> {
    for (i, item) in elems.iter().enumerate() {
        if i > 0 {
            str.try_push(' ')?;
        }
        str.try_push_str(item)?;
    }
    Ok(())
}

fn lines_read_noempty<T: BufRead>(lines: &mut Lines<T>) -> Result<Option<String>> {
    while let Some(s) = lines.next().transpose()? {
        if s.is_empty() {
            continue
        }
        assert_trailing_leading(&s)?;
        return Ok(Some(s))
    }
    Ok(None)
}

#[inline]
fn assert_trailing_leading(s: &str) -> Result<()> {
    if s.is_empty() || s.as_bytes()[0] == 32 || s.as_bytes()[s.len() - 1] == 32 {
        return Err(IllegalWhitespaceError(s.to_string()))
    }
    Ok(())
}

fn is_cif_number(num: &str, bytes_per_pixel: u32) -> Result<ArrayVec<&str, 4_usize>> {
    let split = num.split(';').collect::<ArrayVec<_, 4>>();
    if split.len() != bytes_per_pixel as usize {
        return Err(InvalidPixelError(num.to_string()))
    } else {
        Ok(split)
    }
}

fn unfuck_cif_number(number: &str) -> Result<u32> {
    assert_trailing_leading(number)?;
    let mut buf = ArrayString::<2048>::new();
    let split = number.split_ascii_whitespace().collect::<ArrayVec<_, 64>>();
    let splitlen = split.len();
    for (i, word) in split.iter().enumerate() {
        if !word.starts_with("ty") {
            continue
        }
        let thousands = match *word {
            "tysiąc" => {
                if i == 0 {
                    &1_u16
                } else {
                    return Err(GrammarError(number.to_string()))
                }
            }
            "tysięcy" | "tysiące" => {
                if i > 0 {
                    join_to_arraystring(&split[..i], &mut buf)?;
                    nummap::U16_NUMMAP.get(&buf).ok_or_else(|| GrammarError(number.to_string()))?
                } else {
                    return Err(GrammarError(number.to_string()))
                }
            }
            _ => return Err(GrammarError(number.to_string())),
        };
        let remainder = if i + 1 < splitlen {
            buf.clear();
            join_to_arraystring(&split[i + 1..], &mut buf)?;
            nummap::U16_NUMMAP.get(&buf).ok_or_else(|| GrammarError(number.to_string()))?
        } else {
            &0_u16
        };
        return Ok(u32::from(*thousands) * 1000 + u32::from(*remainder))
    }
    Ok(u32::from(*nummap::U16_NUMMAP.get(number).ok_or_else(|| GrammarError(number.to_string()))?))
}

fn unfuck_cif_number_fast(number: &str) -> Result<u8> {
    assert_trailing_leading(number)?;
    let mut buf = ArrayString::<2048>::new();
    let split = number.split_ascii_whitespace().take(8).collect::<ArrayVec<_, 64>>();

    join_to_arraystring(&split, &mut buf)?;
    let number = *(nummap::U8_NUMMAP.get(&buf).ok_or_else(|| InvalidPixelError(number.to_string()))?);

    Ok(number)
}

fn decoder(inputfile: &str, outputfile: &str) -> Result<()> {
    let infile = File::open(inputfile)?;
    let outfile = File::create(outputfile)?;
    let mut lines = BufReader::new(infile).lines();
    let rawriter = BufWriter::new(outfile);

    // "CIF: <flags>"
    if !lines.next().transpose()?.ok_or(InvalidHeaderError)?.starts_with("CIF:") {
        return Err(InvalidHeaderError)
    }

    // "WERSJA jeden"
    let version_str = lines_read_noempty(&mut lines)?.ok_or(InvalidHeaderError)?;
    let version_split = version_str.split_ascii_whitespace().take(2).collect::<ArrayVec<_, 2>>();
    if version_split.len() != 2 || version_split[0] != "WERSJA" || version_split[1] != "jeden" {
        return Err(InvalidHeaderError)
    }

    // "ROZMIAR szerokość: osiem, wysokość: osiem, bitów_na_piksel: trzydzieści dwa"
    let size_string = lines_read_noempty(&mut lines)?.ok_or(InvalidHeaderError)?;
    let size_split = size_string
        .strip_prefix("ROZMIAR")
        .ok_or_else(|| InvalidSizeError(size_string.to_string()))?
        .split(',')
        .take(3)
        .collect::<ArrayVec<_, 3>>();
    if size_split.len() != 3 {
        return Err(InvalidSizeError(size_string.to_string()))
    }

    let width = unfuck_cif_number(
        size_split[0]
            .trim_start()
            .strip_prefix("szerokość:")
            .ok_or_else(|| InvalidSizeError(size_string.to_string()))?
            .trim_start(),
    )?;
    let height = unfuck_cif_number(
        size_split[1]
            .trim_start()
            .strip_prefix("wysokość:")
            .ok_or_else(|| InvalidSizeError(size_string.to_string()))?
            .trim_start(),
    )?;

    let format = match unfuck_cif_number_fast(
        size_split[2]
            .trim_start()
            .strip_prefix("bitów_na_piksel:")
            .ok_or_else(|| InvalidSizeError(size_string.to_string()))?
            .trim_start(),
    )? {
        24 => ColorType::Rgb,
        32 => ColorType::Rgba,
        _ => return Err(InvalidSizeError(size_string.to_string())),
    };

    if width == 0 || height == 0 {
        return Err(NoDataError)
    }

    let mut outpng = png::Encoder::new(rawriter, width, height);
    outpng.set_color(format);
    outpng.set_depth(BitDepth::Eight);

    let bytes_per_pixel = if format == ColorType::Rgb { 3 } else { 4 };

    let mut md_head = false;
    let mut md_txt = ArrayString::<2048>::new();
    let mut md_key = ArrayString::<2048>::new();

    let first = loop {
        if let Some(line) = lines_read_noempty(&mut lines)? {
            // So this is still some cringe code
            // But currently it works
            if line.starts_with("METADANE ") {
                if md_head {
                    let split = line.split_ascii_whitespace().collect::<ArrayVec<_, 256>>();
                    if split.len() > 2 {
                        return Err(InvalidMetadataError("Metadata values must not contain line feeds.".to_string()))
                    }
                    md_txt.push_str(&line[8..]);
                    continue
                } else {
                    md_head = true;
                    let mut buf = ArrayString::<2048>::new();
                    let split = line.split_ascii_whitespace().collect::<ArrayVec<_, 256>>();
                    join_to_arraystring(&split, &mut buf)?;
                    let md_split = buf.splitn(3, ' ').collect::<ArrayVec<_, 3>>();
                    if md_split.len() != 3 {
                        return Err(InvalidMetadataError(line.to_string()))
                    }
                    md_key.push_str(md_split[1]);
                    md_txt.push_str(md_split[2]);
                    continue
                }
            } else if is_cif_number(&line, bytes_per_pixel).is_err() {
                md_txt.push_str(&line);
                continue
            } else {
                outpng.add_itxt_chunk(md_key.to_string(), md_txt.to_string())?;
                break line
            }
        }
        return Err(NoDataError)
    };

    let mut outpng = outpng.write_header()?;

    let mut pixmap = Vec::with_capacity((bytes_per_pixel * width * height) as usize);

    if !first.is_empty() {
        let px_split = first.split(';').collect::<ArrayVec<_, 4>>();
        if px_split.len() != bytes_per_pixel as usize {
            return Err(InvalidPixelError(first.to_string()))
        }
        for px in px_split {
            pixmap.push(unfuck_cif_number_fast(px.trim_start())?);
        }
    }

    while let Some(line) = lines_read_noempty(&mut lines)? {
        let px_split = line.split(';').collect::<ArrayVec<_, 4>>();
        if px_split.len() != bytes_per_pixel as usize {
            return Err(InvalidPixelError(line.to_string()))
        }
        for px in px_split {
            pixmap.push(unfuck_cif_number_fast(px.trim())?);
        }
    }

    outpng.write_image_data(&pixmap)?;

    Ok(())
}

fn main() {
    let argv = env::args().skip(1).take(2).collect::<ArrayVec<_, 2>>();
    if argv.len() != 2 {
        eprintln!("Invalid usage;\nUsage: zardzewialy-dekoder-cif <input cif file> <output bmp file>");
        process::exit(1);
    }
    if let Err(e) = decoder(&argv[0], &argv[1]) {
        eprintln!("Error: {}", e);
        process::exit(1);
    }
}