#![allow(dead_code)]
mod crc;
mod header;
mod header_tests;
mod metadata;
mod metadata_tests;
mod tests;

pub use self::header::Header;
pub use self::metadata::make_distribution_string;
pub use self::metadata::make_too_much_meta_err_string;
pub use self::metadata::Metadata;
pub use self::metadata::MetadataID;
use smallvec::SmallVec;

pub fn meta_to_meta_id(meta: &Metadata) -> MetadataID {
    self::metadata::meta_to_id(meta)
}

pub fn meta_id_to_str(id: MetadataID) -> &'static str {
    self::metadata::id_to_str(id)
}

pub fn get_meta_ref_by_meta_id(metas: &[Metadata], id: MetadataID) -> Option<&Metadata> {
    self::metadata::get_meta_ref_by_id(metas, id)
}

pub fn get_meta_ref_mut_by_meta_id(
    metas: &mut [Metadata],
    id: MetadataID,
) -> Option<&mut Metadata> {
    self::metadata::get_meta_ref_mut_by_id(metas, id)
}

use self::crc::*;
use crate::sbx_specs::{
    ver_to_block_size, ver_to_data_size, ver_uses_rs, Version, SBX_FILE_UID_LEN,
    SBX_FIRST_DATA_SEQ_NUM, SBX_HEADER_SIZE,
};

use crate::multihash;

macro_rules! make_meta_getter {
    (
        $func_name:ident => $meta_id:ident => ret_ref $ret_type:ty
    ) => {
        #[allow(non_snake_case)]
        pub fn $func_name (&self) -> Result<Option<&$ret_type>, Error> {
            match self.get_meta_ref_by_id(MetadataID::$meta_id)? {
                None                        => Ok(None),
                Some(Metadata::$meta_id(x)) => Ok(Some(x)),
                _                           => unreachable!(),
            }
        }
    };
    (
        $func_name:ident => $meta_id:ident => ret_val $ret_type:ty
    ) => {
        #[allow(non_snake_case)]
        pub fn $func_name (&self) -> Result<Option<$ret_type>, Error> {
            match self.get_meta_ref_by_id(MetadataID::$meta_id)? {
                None                         => Ok(None),
                Some(&Metadata::$meta_id(x)) => Ok(Some(x)),
                _                            => panic!(),
            }
        }
    };
}

macro_rules! check_ver_consistent_with_opt {
    (
        $version:expr, $val:expr
    ) => {{
        match $val {
            None => assert!(!ver_uses_rs($version)),
            Some(_) => assert!(ver_uses_rs($version)),
        }
    }};
}

#[derive(Clone, Copy, Debug, PartialEq)]
pub enum BlockType {
    Data,
    Meta,
}

#[derive(Clone, Debug, PartialEq)]
pub enum Error {
    IncorrectBlockType,
    IncorrectBufferSize,
    TooMuchMetadata(Vec<Metadata>),
    InvalidCRC,
    SeqNumOverflow,
    ParseError,
    FailedPred,
}

#[derive(Clone, Debug, PartialEq)]
pub enum Data {
    Data,
    Meta(Vec<Metadata>),
}

#[derive(Clone, Debug, PartialEq)]
pub struct Block {
    header: Header,
    data: Data,
}

macro_rules! slice_buf {
    (
        whole => $self:ident, $buf:ident
    ) => {
        &$buf[..block_size!($self)]
    };
    (
        whole_mut => $self:ident, $buf:ident
    ) => {
        &mut $buf[..block_size!($self)]
    };
    (
        header => $self:ident, $buf:ident
    ) => {
        &$buf[..SBX_HEADER_SIZE]
    };
    (
        header_mut => $self:ident, $buf:ident
    ) => {
        &mut $buf[..SBX_HEADER_SIZE]
    };
    (
        data => $self:ident, $buf:ident
    ) => {
        &$buf[SBX_HEADER_SIZE..block_size!($self)]
    };
    (
        data_mut => $self:ident, $buf:ident
    ) => {
        &mut $buf[SBX_HEADER_SIZE..block_size!($self)]
    };
}

macro_rules! check_buffer {
    (
        $self:ident, $buf:ident
    ) => {
        if $buf.len() < block_size!($self) {
            panic!("Insufficient buffer size");
        }
    };
}

macro_rules! block_size {
    (
        $self:ident
    ) => {
        ver_to_block_size($self.header.version)
    };
}

/*macro_rules! data_size {
    (
        $self:ident
    ) => {
        ver_to_data_size($self.header.version)
    }
}*/

pub fn write_padding(version: Version, skip: usize, buffer: &mut [u8]) -> usize {
    let block_size = ver_to_block_size(version);
    let start = SBX_HEADER_SIZE + skip;

    for i in start..block_size {
        buffer[i] = 0x1A;
    }

    block_size - start
}

pub fn slice_buf(version: Version, buffer: &[u8]) -> &[u8] {
    &buffer[..ver_to_block_size(version)]
}

pub fn slice_buf_mut(version: Version, buffer: &mut [u8]) -> &mut [u8] {
    &mut buffer[..ver_to_block_size(version)]
}

pub fn slice_header_buf(buffer: &[u8]) -> &[u8] {
    &buffer[..SBX_HEADER_SIZE]
}

pub fn slice_header_buf_mut(buffer: &mut [u8]) -> &mut [u8] {
    &mut buffer[..SBX_HEADER_SIZE]
}

pub fn slice_data_buf(version: Version, buffer: &[u8]) -> &[u8] {
    &buffer[SBX_HEADER_SIZE..ver_to_block_size(version)]
}

pub fn slice_data_buf_mut(version: Version, buffer: &mut [u8]) -> &mut [u8] {
    &mut buffer[SBX_HEADER_SIZE..ver_to_block_size(version)]
}

pub fn check_if_buffer_valid(buffer: &[u8]) -> bool {
    let mut block = Block::new(Version::V1, b"\x00\x00\x00\x00\x00\x00", BlockType::Data);

    match block.sync_from_buffer(buffer, None, None) {
        Ok(()) => {}
        Err(_) => {
            return false;
        }
    }

    block.verify_crc(buffer).unwrap()
}

pub fn seq_num_is_meta(seq_num: u32) -> bool {
    seq_num == 0
}

pub fn seq_num_is_parity(seq_num: u32, data_shards: usize, parity_shards: usize) -> bool {
    if seq_num == 0 {
        false // this is metadata block
    } else {
        // data sets
        let index = seq_num - SBX_FIRST_DATA_SEQ_NUM as u32;
        let index_in_set = index % (data_shards + parity_shards) as u32;

        (data_shards as u32 <= index_in_set)
    }
}

pub fn seq_num_is_parity_w_data_par_burst(
    seq_num: u32,
    data_par_burst: Option<(usize, usize, usize)>,
) -> bool {
    match data_par_burst {
        Some((data, parity, _)) => seq_num_is_parity(seq_num, data, parity),
        None => false,
    }
}

pub fn calc_meta_block_dup_write_pos_s(
    version: Version,
    data_par_burst: Option<(usize, usize, usize)>,
) -> SmallVec<[u64; 32]> {
    check_ver_consistent_with_opt!(version, data_par_burst);

    let block_size = ver_to_block_size(version) as u64;

    let mut res = calc_meta_block_dup_write_indices(data_par_burst);

    for i in res.iter_mut() {
        *i = *i * block_size;
    }

    res
}

pub fn calc_meta_block_dup_write_indices(
    data_par_burst: Option<(usize, usize, usize)>,
) -> SmallVec<[u64; 32]> {
    match data_par_burst {
        Some((_, parity, burst)) => {
            let mut res: SmallVec<[u64; 32]> = SmallVec::with_capacity(1 + parity);

            for i in 1..1 + parity as u64 {
                res.push(i * (1 + burst) as u64);
            }

            res
        }
        None => SmallVec::new(),
    }
}

pub fn calc_meta_block_all_write_pos_s(
    version: Version,
    data_par_burst: Option<(usize, usize, usize)>,
) -> SmallVec<[u64; 32]> {
    let mut res = calc_meta_block_dup_write_pos_s(version, data_par_burst);

    res.push(0);

    res.sort();

    res
}

pub fn calc_meta_block_all_write_indices(
    data_par_burst: Option<(usize, usize, usize)>,
) -> SmallVec<[u64; 32]> {
    let mut res = calc_meta_block_dup_write_indices(data_par_burst);

    res.push(0);

    res.sort();

    res
}

pub fn calc_data_block_write_pos(
    version: Version,
    seq_num: u32,
    meta_enabled: Option<bool>,
    data_par_burst: Option<(usize, usize, usize)>,
) -> u64 {
    check_ver_consistent_with_opt!(version, data_par_burst);

    let block_size = ver_to_block_size(version) as u64;

    calc_data_block_write_index(seq_num, meta_enabled, data_par_burst) * block_size
}

pub fn calc_data_block_write_index(
    seq_num: u32,
    meta_enabled: Option<bool>,
    data_par_burst: Option<(usize, usize, usize)>,
) -> u64 {
    // the following transforms seq num to data index
    // then do the transformation based on data index
    assert!(seq_num >= SBX_FIRST_DATA_SEQ_NUM);

    // calculate the sequential data index
    let index = (seq_num - SBX_FIRST_DATA_SEQ_NUM) as u64;

    match data_par_burst {
        None => {
            let meta_enabled = meta_enabled.unwrap_or(true);

            if meta_enabled {
                SBX_FIRST_DATA_SEQ_NUM as u64 + index
            } else {
                index
            }
        }
        Some((data, parity, burst)) => {
            shadow_to_avoid_use!(meta_enabled);

            if burst == 0 {
                let meta_block_count = 1 + parity as u64;

                return meta_block_count + index;
            }

            let data_shards = data as u64;
            let parity_shards = parity as u64;
            let burst_err_resistance = burst as u64;

            let super_block_set_size = (data_shards + parity_shards) * burst_err_resistance;

            // sub A block set partitioning deals with the super block set
            // of the sequential data index arrangement
            // i.e. sub A = partitioning of input
            //
            // sub B block set partitioning deals with the super block set
            // of the interleaving data index arrangement
            // i.e. sub B = partitioning of output
            //
            // sub A block set partitioning slices at total shards interval
            // sub B block set partitioning slices at burst resistance level interval
            let sub_a_block_set_size = data_shards + parity_shards;
            let sub_b_block_set_size = burst_err_resistance;

            // calculate the index of the start of super block set with
            // respect to the data index
            let super_block_set_index = index / super_block_set_size;
            // calculate index of current seq num inside the current super block set
            let index_in_super_block_set = index % super_block_set_size;

            // calculate the index of the start of sub A block set inside
            // the current super block set
            let sub_a_block_set_index = index_in_super_block_set / sub_a_block_set_size;
            // calculate index of current seq num inside the current sub A block set
            let index_in_sub_a_block_set = index_in_super_block_set % sub_a_block_set_size;

            let sub_b_block_set_index = index_in_sub_a_block_set;
            let index_in_sub_b_block_set = sub_a_block_set_index;

            let new_index_in_super_block_set =
                sub_b_block_set_index * sub_b_block_set_size + index_in_sub_b_block_set;

            // M = data_shards
            // N = parity_shards
            //
            // calculate the number of metadata blocks before the current
            // seq num in the interleaving scheme
            let meta_block_count = if super_block_set_index == 0 {
                // first super block set
                // one metadata block at front of first (1 + N) sub B blocks
                if sub_b_block_set_index < 1 + parity_shards {
                    1 + sub_b_block_set_index
                } else {
                    1 + parity_shards
                }
            } else {
                1 + parity_shards
            };

            // finally calculate the index in interleaving data index arrangement
            let new_index =
            // number of metadata blocks in front of the data block
                meta_block_count

            // index of start of super block set
                + (super_block_set_size * super_block_set_index)

            // index inside the super block set
                + new_index_in_super_block_set;

            new_index
        }
    }
}

pub fn calc_data_chunk_write_index(seq_num: u32, data_par: Option<(usize, usize)>) -> Option<u64> {
    if seq_num < SBX_FIRST_DATA_SEQ_NUM {
        None
    } else {
        let index = (seq_num - SBX_FIRST_DATA_SEQ_NUM) as u64;

        match data_par {
            None => Some(index),
            Some((data, parity)) => {
                if seq_num_is_parity(seq_num, data, parity) {
                    None
                } else {
                    let block_set_index = index / (data + parity) as u64;
                    let index_in_block_set = index % (data + parity) as u64;

                    Some(block_set_index * data as u64 + index_in_block_set)
                }
            }
        }
    }
}

pub fn calc_data_chunk_write_pos(
    version: Version,
    seq_num: u32,
    data_par: Option<(usize, usize)>,
) -> Option<u64> {
    check_ver_consistent_with_opt!(version, data_par);

    let data_size = ver_to_data_size(version);

    match calc_data_chunk_write_index(seq_num, data_par) {
        None => None,
        Some(x) => Some(x as u64 * data_size as u64),
    }
}

pub fn calc_seq_num_at_index(
    index: u64,
    meta_enabled: Option<bool>,
    data_par_burst: Option<(usize, usize, usize)>,
) -> u32 {
    match data_par_burst {
        None => {
            let meta_enabled = meta_enabled.unwrap_or(true);

            if meta_enabled {
                index as u32
            } else {
                SBX_FIRST_DATA_SEQ_NUM + index as u32
            }
        }
        Some((data, parity, burst)) => {
            shadow_to_avoid_use!(meta_enabled);

            // the following essentially reverses the index transformation in
            // calc_data_block_write_index
            if burst == 0 {
                if index < 1 + parity as u64 {
                    return 0;
                } else {
                    let data_index = index - (1 + parity) as u64;

                    return (data_index + 1) as u32;
                }
            }

            let data_shards = data as u64;
            let parity_shards = parity as u64;
            let burst_err_resistance = burst as u64;

            // handle metadata seq nums first
            // M = data shards
            // N = parity_shards
            // B = burst_err_resistance
            //
            // if index is in first 1 + N block set
            if index < (1 + parity_shards) * (1 + burst_err_resistance)
            // and index is in front of a sub B block set
                && index % (1 + burst_err_resistance) == 0
            {
                return 0;
            }

            let meta_block_count =
            // if index is in first 1 + N block set
                if index < (1 + parity_shards) * (1 + burst_err_resistance) {
                    1 + index / (1 + burst_err_resistance)
                } else {
                    1 + parity_shards
                };

            // same block set sizes from `calc_data_block_write_index`
            let super_block_set_size = (data_shards + parity_shards) * burst_err_resistance;

            let sub_a_block_set_size = data_shards + parity_shards;
            let sub_b_block_set_size = burst_err_resistance;

            // calculate the transformed data index
            // not the original sequential data index yet
            let index_without_meta = index - meta_block_count;

            // reverse the transformation done in `calc_data_block_write_index`
            let super_block_set_index = index_without_meta / super_block_set_size;
            let index_in_super_block_set = index_without_meta % super_block_set_size;

            let sub_b_block_set_index = index_in_super_block_set / sub_b_block_set_size;
            let index_in_sub_b_block_set = index_in_super_block_set % sub_b_block_set_size;

            let sub_a_block_set_index = index_in_sub_b_block_set;
            let index_in_sub_a_block_set = sub_b_block_set_index;

            let old_index_in_super_block_set =
                sub_a_block_set_index * sub_a_block_set_size + index_in_sub_a_block_set;

            // calculate the original sequential data index
            let old_index =
            // index of start of super block set
                (super_block_set_size * super_block_set_index)

            // index inside the super block set
                + old_index_in_super_block_set;

            (old_index as u32) + SBX_FIRST_DATA_SEQ_NUM as u32
        }
    }
}

impl Block {
    pub fn new(version: Version, uid: &[u8; SBX_FILE_UID_LEN], block_type: BlockType) -> Block {
        match block_type {
            BlockType::Data => {
                let seq_num = SBX_FIRST_DATA_SEQ_NUM as u32;
                Block {
                    header: Header::new(version, uid.clone(), seq_num),
                    data: Data::Data,
                }
            }
            BlockType::Meta => {
                let seq_num = 0 as u32;
                Block {
                    header: Header::new(version, uid.clone(), seq_num),
                    data: Data::Meta(Vec::with_capacity(10)),
                }
            }
        }
    }

    pub fn dummy() -> Block {
        let version = Version::V1;
        let seq_num = SBX_FIRST_DATA_SEQ_NUM as u32;
        Block {
            header: Header::new(version, [0; 6], seq_num),
            data: Data::Data,
        }
    }

    pub fn get_version(&self) -> Version {
        self.header.version
    }

    pub fn set_version(&mut self, version: Version) {
        self.header.version = version;
    }

    pub fn get_uid(&self) -> [u8; SBX_FILE_UID_LEN] {
        self.header.uid
    }

    pub fn set_uid(&mut self, uid: [u8; SBX_FILE_UID_LEN]) {
        self.header.uid = uid;
    }

    pub fn get_crc(&self) -> u16 {
        self.header.crc
    }

    pub fn get_seq_num(&self) -> u32 {
        self.header.seq_num
    }

    pub fn set_seq_num(&mut self, seq_num: u32) {
        self.header.seq_num = seq_num;

        self.switch_block_type_to_match_header();
    }

    pub fn add_seq_num(&mut self, val: u32) -> Result<(), Error> {
        match self.header.seq_num.checked_add(val) {
            None => {
                return Err(Error::SeqNumOverflow);
            }
            Some(x) => {
                self.header.seq_num = x;
            }
        }

        self.switch_block_type_to_match_header();

        Ok(())
    }

    pub fn add1_seq_num(&mut self) -> Result<(), Error> {
        self.add_seq_num(1)
    }

    pub fn block_type(&self) -> BlockType {
        match self.data {
            Data::Data => BlockType::Data,
            Data::Meta(_) => BlockType::Meta,
        }
    }

    pub fn is_meta(&self) -> bool {
        match self.block_type() {
            BlockType::Data => false,
            BlockType::Meta => true,
        }
    }

    pub fn is_data(&self) -> bool {
        match self.block_type() {
            BlockType::Data => true,
            BlockType::Meta => false,
        }
    }

    pub fn is_parity(&self, data_shards: usize, parity_shards: usize) -> bool {
        ver_uses_rs(self.header.version)
            && seq_num_is_parity(self.get_seq_num(), data_shards, parity_shards)
    }

    pub fn is_parity_w_data_par_burst(
        &self,
        data_par_burst: Option<(usize, usize, usize)>,
    ) -> bool {
        ver_uses_rs(self.header.version)
            && seq_num_is_parity_w_data_par_burst(self.get_seq_num(), data_par_burst)
    }

    pub fn get_meta_ref_by_id(&self, id: MetadataID) -> Result<Option<&Metadata>, Error> {
        match self.data {
            Data::Data => Err(Error::IncorrectBlockType),
            Data::Meta(ref metas) => Ok(metadata::get_meta_ref_by_id(metas, id)),
        }
    }

    pub fn get_meta_ref_mut_by_id(
        &mut self,
        id: MetadataID,
    ) -> Result<Option<&mut Metadata>, Error> {
        match self.data {
            Data::Data => Err(Error::IncorrectBlockType),
            Data::Meta(ref mut metas) => Ok(metadata::get_meta_ref_mut_by_id(metas, id)),
        }
    }

    make_meta_getter!(get_FNM => FNM => ret_ref str);
    make_meta_getter!(get_SNM => SNM => ret_ref str);
    make_meta_getter!(get_FSZ => FSZ => ret_val u64);
    make_meta_getter!(get_FDT => FDT => ret_val i64);
    make_meta_getter!(get_SDT => SDT => ret_val i64);
    make_meta_getter!(get_HSH => HSH => ret_ref multihash::HashBytes);
    make_meta_getter!(get_RSD => RSD => ret_val u8);
    make_meta_getter!(get_RSP => RSP => ret_val u8);

    pub fn metas(&self) -> Result<&Vec<Metadata>, Error> {
        match self.data {
            Data::Data => Err(Error::IncorrectBlockType),
            Data::Meta(ref meta) => Ok(meta),
        }
    }

    pub fn metas_mut(&mut self) -> Result<&mut Vec<Metadata>, Error> {
        match self.data {
            Data::Data => Err(Error::IncorrectBlockType),
            Data::Meta(ref mut meta) => Ok(meta),
        }
    }

    pub fn update_meta(&mut self, m: &Metadata) -> Result<(), Error> {
        match self.data {
            Data::Data => Err(Error::IncorrectBlockType),
            Data::Meta(ref mut metas) => {
                let id = metadata::meta_to_id(m);
                let m = m.clone();
                match metadata::get_meta_ref_mut_by_id(metas, id) {
                    None => metas.push(m),
                    Some(x) => *x = m,
                };
                Ok(())
            }
        }
    }

    pub fn update_metas(&mut self, ms: &[Metadata]) -> Result<(), Error> {
        for m in ms {
            if let Err(e) = self.update_meta(m) {
                return Err(e);
            }
        }
        Ok(())
    }

    pub fn remove_metas(&mut self, ids: &[MetadataID]) -> Result<(), Error> {
        match self.data {
            Data::Data => Err(Error::IncorrectBlockType),
            Data::Meta(ref mut metas) => {
                metas.retain(|m| !ids.contains(&metadata::meta_to_id(m)));
                Ok(())
            }
        }
    }

    pub fn calc_crc(&self, buffer: &[u8]) -> u16 {
        check_buffer!(self, buffer);

        let crc = self.header.calc_crc();

        crc_ccitt_generic(crc, slice_buf!(data => self, buffer))
    }

    pub fn update_crc(&mut self, buffer: &[u8]) {
        self.header.crc = self.calc_crc(buffer);
    }

    fn header_type_matches_block_type(&self) -> bool {
        self.header.header_type() == self.block_type()
    }

    pub fn sync_to_buffer(
        &mut self,
        update_crc: Option<bool>,
        buffer: &mut [u8],
    ) -> Result<(), Error> {
        check_buffer!(self, buffer);

        let update_crc = update_crc.unwrap_or(true);

        match self.data {
            Data::Meta(ref meta) => {
                if self.get_seq_num() == 0 {
                    // not a metadata parity block
                    // transform metadata to bytes
                    metadata::to_bytes(meta, slice_buf!(data_mut => self, buffer))?;
                }
            }
            Data::Data => {}
        }

        match self.block_type() {
            BlockType::Data => {
                if update_crc {
                    self.update_crc(buffer)
                }
            }
            BlockType::Meta => self.update_crc(buffer),
        }

        self.header.to_bytes(slice_buf!(header_mut => self, buffer));

        Ok(())
    }

    fn switch_block_type(&mut self) {
        let block_type = self.block_type();

        if block_type == BlockType::Meta {
            self.data = Data::Data;
        } else {
            self.data = Data::Meta(Vec::with_capacity(10));
        }
    }

    fn switch_block_type_to_match_header(&mut self) {
        if !self.header_type_matches_block_type() {
            self.switch_block_type();
        }
    }

    pub fn sync_from_buffer_header_only(&mut self, buffer: &[u8]) -> Result<(), Error> {
        self.header.from_bytes(slice_buf!(header => self, buffer))?;

        self.switch_block_type_to_match_header();

        Ok(())
    }

    pub fn sync_from_buffer(
        &mut self,
        buffer: &[u8],
        header_pred: Option<&Fn(&Header) -> bool>,
        pred: Option<&Fn(&Block) -> bool>,
    ) -> Result<(), Error> {
        self.sync_from_buffer_header_only(buffer)?;

        if let Some(pred) = header_pred {
            if !pred(&self.header) {
                return Err(Error::FailedPred);
            }
        }

        check_buffer!(self, buffer);

        self.enforce_crc(buffer)?;

        match self.data {
            Data::Meta(ref mut meta) => {
                // parse if it is metadata
                if self.header.seq_num == 0 {
                    meta.clear();
                    let res = metadata::from_bytes(slice_buf!(data => self, buffer))?;
                    for r in res.into_iter() {
                        meta.push(r);
                    }
                }
            }
            Data::Data => {}
        }

        match pred {
            Some(pred) => {
                if pred(&self) {
                    Ok(())
                } else {
                    Err(Error::FailedPred)
                }
            }
            None => Ok(()),
        }
    }

    pub fn verify_crc(&self, buffer: &[u8]) -> Result<bool, Error> {
        Ok(self.header.crc == self.calc_crc(buffer))
    }

    pub fn enforce_crc(&self, buffer: &[u8]) -> Result<(), Error> {
        if self.verify_crc(buffer)? {
            Ok(())
        } else {
            Err(Error::InvalidCRC)
        }
    }
}