//! Marathon Wad format handling.

use crate::durandal::{bin::*, err::*, text::mac_roman_conv};
use serde::Serialize;
use std::{collections::BTreeMap, fmt};

impl Wad<'_>
{
   pub fn new(b: &[u8]) -> ResultS<Wad<'_>>
   {
      read_data! {
         128, BE in b =>
         wadver   = u16[0];
         dataver  = u16[2];
         origname = mac_roman_conv[4..68] nt;
         dirofs   = u32[72] as usize;
         numents  = u16[76] as usize;
         appsize  = u16[78] as usize;
         wcnksize = u16[80] as usize;
         wentsize = u16[82] as usize;
      }

      let wadver = Ver::from_repr(wadver)?;

      let is_old = match wadver {
         Ver::Base => true,
         _ => false,
      };

      let entsize = if is_old {8 } else {10};
      let cnksize = if is_old {12} else {16};

      if entsize != wentsize {
         bail!("invalid entry size");
      }

      if cnksize != wcnksize {
         bail!("invalid chunk size");
      }

      let mut entries = EntryMap::new();
      let mut p = dirofs;

      for i in 0..numents {
         read_data! {
            p + entsize, BE in b =>
            offset = u32[p] as usize;
            size   = u32[p + 4] as usize;
            index  = u16[p + 8];
         }

         let index = if is_old {i as u16} else {index};

         let cnkdata = &b[offset..offset + size];
         let chunks  = get_chunks(cnkdata, cnksize)?;
         let appdata = &b[p..p + appsize];

         entries.insert(index, Entry{chunks, appdata});

         p += entsize + appsize;
      }

      Ok(Wad{head: WadHeader{wadver, dataver, appsize, origname}, entries})
   }
}

fn get_chunks(b: &[u8], cnksize: usize) -> ResultS<ChunkMap<'_>>
{
   let mut chunks = ChunkMap::new();
   let mut p = 0;

   while p < b.len() {
      read_data! {
         p + cnksize, BE in b =>
         iden = iden[p];
         size = u32[p + 8] as usize;
      }

      let beg = p + cnksize;
      let end = beg + size;

      chunks.insert(iden, &b[beg..end]);

      p = end;
   }

   Ok(chunks)
}

type Chunk<'a> = &'a [u8];
type ChunkMap<'a> = BTreeMap<Ident, Chunk<'a>>;
type EntryMap<'a> = BTreeMap<u16, Entry<'a>>;

#[derive(Serialize)]
pub struct Entry<'a>
{
   pub chunks:  ChunkMap<'a>,
   pub appdata: &'a [u8],
}

#[derive(Debug, Serialize)]
pub struct WadHeader
{
   pub wadver:   Ver,
   pub dataver:  u16,
   pub origname: String,
   pub appsize:  usize,
}

#[derive(Debug, Serialize)]
pub struct Wad<'a>
{
   pub head:    WadHeader,
   pub entries: EntryMap<'a>,
}

c_enum! {
   #[derive(Debug, Serialize)]
   pub enum Ver: u16
   {
      0 => Base,
      1 => Dir,
      2 => Over,
      4 => Inf,
   }
}

impl fmt::Debug for Entry<'_>
{
   fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
   {
      write!(f, "Entry{{ ")?;
      for iden in self.chunks.keys() {
         write!(f, "{} ", mac_roman_conv(iden))?;
      }
      if !self.appdata.is_empty() {
         write!(f, "\nappdata: {:?} ", self.appdata)?;
      }
      write!(f, "}}")
   }
}

// EOF