#![no_std]
extern crate alloc;

use core::fmt;
use alloc::{string::FromUtf8Error, string::String, vec::Vec, rc::Rc};
use core_io::{self as io, BufRead, BufReader, Read, Write, Seek, SeekFrom};
use libboard_zynq::sdio;

pub mod sd_reader;
pub mod net_settings;
pub mod bootgen;

#[derive(Debug)]
pub enum Error<'a> {
    SdError(sdio::sd_card::CardInitializationError),
    IoError(io::Error),
    Utf8Error(FromUtf8Error),
    KeyNotFoundError(&'a str),
    NoConfig,
}

pub type Result<'a, T> = core::result::Result<T, Error<'a>>;

impl<'a> fmt::Display for Error<'a> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Error::SdError(error) => write!(f, "SD error: {}", error),
            Error::IoError(error) => write!(f, "I/O error: {}", error),
            Error::Utf8Error(error) => write!(f, "UTF-8 error: {}", error),
            Error::KeyNotFoundError(name) => write!(f, "Configuration key `{}` not found", name),
            Error::NoConfig => write!(f, "Configuration not present"),
        }
    }
}

impl<'a> From<sdio::sd_card::CardInitializationError> for Error<'a> {
    fn from(error: sdio::sd_card::CardInitializationError) -> Self {
        Error::SdError(error)
    }
}

impl<'a> From<io::Error> for Error<'a> {
    fn from(error: io::Error) -> Self {
        Error::IoError(error)
    }
}

impl<'a> From<FromUtf8Error> for Error<'a> {
    fn from(error: FromUtf8Error) -> Self {
        Error::Utf8Error(error)
    }
}

fn parse_config<'a>(
    key: &'a str,
    buffer: &mut Vec<u8>,
    file: fatfs::File<sd_reader::SdReader>,
) -> Result<'a, ()> {
    let prefix = [key, "="].concat().to_ascii_lowercase();
    for line in BufReader::new(file).lines() {
        let line = line?.to_ascii_lowercase();
        if line.starts_with(&prefix) {
            buffer.extend(line[prefix.len()..].as_bytes());
            return Ok(());
        }
    }
    Err(Error::KeyNotFoundError(key))
}

pub struct Config {
    fs: Option<Rc<fatfs::FileSystem<sd_reader::SdReader>>>,
}

const NEWLINE: &[u8] = b"\n";

impl Config {
    pub fn new() -> Result<'static, Self> {
        let sdio = sdio::Sdio::sdio0(true);
        if !sdio.is_card_inserted() {
            Err(sdio::sd_card::CardInitializationError::NoCardInserted)?;
        }
        let sd = sdio::sd_card::SdCard::from_sdio(sdio)?;
        let reader = sd_reader::SdReader::new(sd);

        let fs = reader.mount_fatfs(sd_reader::PartitionEntry::Entry1)?;
        Ok(Config { fs: Some(Rc::new(fs)) })
    }

    pub fn from_fs(fs: Option<Rc<fatfs::FileSystem<sd_reader::SdReader>>>) -> Self {
        Config { fs }
    }

    pub fn new_dummy() -> Self {
        Config { fs: None }
    }

    pub fn read<'b>(&self, key: &'b str) -> Result<'b, Vec<u8>> {
        if let Some(fs) = &self.fs {
            let root_dir = fs.root_dir();
            let mut buffer: Vec<u8> = Vec::new();
            match root_dir.open_file(&["/CONFIG/", key, ".BIN"].concat()) {
                Ok(mut f) => f.read_to_end(&mut buffer).map(|_| ())?,
                Err(_) => match root_dir.open_file("/CONFIG.TXT") {
                    Ok(f) => parse_config(key, &mut buffer, f)?,
                    Err(_) => return Err(Error::KeyNotFoundError(key)),
                },
            };
            Ok(buffer)
        } else {
            Err(Error::NoConfig)
        }
    }

    pub fn read_str<'b>(&self, key: &'b str) -> Result<'b, String> {
        Ok(String::from_utf8(self.read(key)?)?)
    }

    pub fn remove<'b>(&self, key: &'b str) -> Result<'b, ()> {
        if let Some(fs) = &self.fs {
            let root_dir = fs.root_dir();
            match root_dir.remove(&["/CONFIG/", key, ".BIN"].concat()) {
                Ok(()) => Ok(()),
                Err(_) => {
                    let prefix = [key, "="].concat().to_ascii_lowercase();
                    match root_dir.create_file("/CONFIG.TXT") {
                        Ok(mut f) => {
                            let mut buffer = String::new();
                            f.read_to_string(&mut buffer)?;
                            f.seek(SeekFrom::Start(0))?;
                            f.truncate()?;
                            for line in buffer.lines() {
                                if line.len() > 0 && !line.to_ascii_lowercase().starts_with(&prefix) {
                                    f.write(line.as_bytes())?;
                                    f.write(NEWLINE)?;
                                }
                            }
                            Ok(())
                        },
                        Err(_) => Err(Error::KeyNotFoundError(key))
                    }
                }
            }
        } else {
            Err(Error::NoConfig)
        }
    }

    pub fn write<'b>(&self, key: &'b str, value: Vec<u8>) -> Result<'b, ()> {
        if self.fs.is_none() {
            return Err(Error::NoConfig);
        }
        let fs = self.fs.as_ref().unwrap();
        let root_dir = fs.root_dir();
        let is_str = value.len() <= 100 && value.is_ascii() && !value.contains(&b'\n');
        if key == "boot" {
            let mut f = root_dir.create_file("/BOOT.BIN")?;
            f.truncate()?;
            f.write_all(&value)?;
            drop(f);
        } else {
            let _ = self.remove(key);
            if is_str {
                let mut f = root_dir.create_file("/CONFIG.TXT")?;
                f.seek(SeekFrom::End(0))?;
                write!(f, "{}={}\n", key, String::from_utf8(value).unwrap())?;
            } else {
                let dir = root_dir.create_dir("/CONFIG")?;
                let mut f = dir.create_file(&[key, ".BIN"].concat())?;
                f.write_all(&value)?;
            }
        }
        Ok(())
    }
}