//! Marathon Wad format handling.

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

impl Wad<'_>
{
   pub fn new(b: &[u8]) -> ResultS<Wad>
   {
      if b.len() < 128 {return err_msg("not enough data for Wad header");}

      let   wadver = b.c_u16b( 0)?;
      let  dataver = b.c_u16b( 2)?;
      let origname = mac_roman_conv(&b[4..68]);
      //       crc = b.c_u32b(68)?;
      let   dirofs = b.c_u32b(72)? as usize;
      let  numents = b.c_u16b(76)? as usize;
      let  appsize = b.c_u16b(78)? as usize;
      //  chnksize = b.c_u16b(80)?;
      //   entsize = b.c_u16b(82)?;
      //    parent = b.c_u32b(84)?;

      let  wadver = Ver::from_repr(wadver)?;
      let  is_old = match wadver {Ver::Base => true, _ => false};
      let entsize = if is_old {8} else {10};

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

      for i in 0..numents {
         let offset = b.c_u32b(p  )? as usize;
         let   size = b.c_u32b(p+4)? as usize;
         let  index = if !is_old {b.c_u16b(p+8)?} else {i as u16};

         if offset + size > b.len() {return err_msg("not enough data for entry");}

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

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

         p += entsize + appsize;
      }

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

fn get_chunks(b: &[u8], is_old: bool) -> ResultS<ChunkMap>
{
   let chnksize = if !is_old {16} else {12};

   let mut chunks = ChunkMap::new();
   let mut p = 0;

   while p < b.len() {
      let    ident = b.c_iden(p   )?;
      //    offset = b.c_u32b(p+ 4)?;
      let     size = b.c_u32b(p+ 8)? as usize;
      //  patchofs = b.c_u32b(p+12)?;
      let      beg = p + chnksize;
      let      end = beg + size;
      chunks.insert(ident, &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>>;

pub struct Entry<'a>
{
   pub  chunks: ChunkMap<'a>,
   pub appdata: &'a[u8],
}

#[derive(Debug)]
pub struct Wad<'a>
{
         wadver: Ver,
        dataver: u16,
       origname: String,
        appsize: usize,
   pub  entries: EntryMap<'a>,
}

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

impl fmt::Debug for Entry<'_>
{
   fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result
   {
      write!(f, "Entry{{ ")?;
      for (ident, _) in &self.chunks {write!(f, "{} ", mac_roman_conv(ident))?;}
      if self.appdata.len() != 0{write!(f, "\nappdata: {:?} ", self.appdata)?;}
      write!(f, "}}")
   }
}

// EOF