// Decoding metadata from a single crate's metadata

import std::ebmlivec;
import std::ivec;
import std::option;
import std::str;
import std::ioivec;
import std::map::hashmap;
import syntax::ast;
import front::attr;
import middle::ty;
import common::*;
import tydecode::parse_def_id;
import tydecode::parse_ty_data;
import driver::session;
import syntax::print::pprust;
import cstore;

export get_symbol;
export get_tag_variants;
export get_type;
export get_type_param_count;
export get_type_param_kinds;
export lookup_defs;
export get_crate_attributes;
export list_crate_metadata;
export crate_dep;
export get_crate_deps;
export external_resolver;

// A function that takes a def_id relative to the crate being searched and
// returns a def_id relative to the compilation environment, i.e. if we hit a
// def_id for an item defined in another crate, somebody needs to figure out
// what crate that's in and give us a def_id that makes sense for the current
// build.
type external_resolver = fn(&ast::def_id) -> ast::def_id ;

fn lookup_hash(d: &ebmlivec::doc, eq_fn: fn(&u8[]) -> bool , hash: uint) ->
   ebmlivec::doc[] {
    let index = ebmlivec::get_doc(d, tag_index);
    let table = ebmlivec::get_doc(index, tag_index_table);
    let hash_pos = table.start + hash % 256u * 4u;
    let pos = ebmlivec::be_uint_from_bytes(d.data, hash_pos, 4u);
    let bucket = ebmlivec::doc_at(d.data, pos);
    // Awkward logic because we can't ret from foreach yet

    let result: ebmlivec::doc[] = ~[];
    let belt = tag_index_buckets_bucket_elt;
    for each elt: ebmlivec::doc  in ebmlivec::tagged_docs(bucket, belt) {
        let pos = ebmlivec::be_uint_from_bytes(elt.data, elt.start, 4u);
        if eq_fn(ivec::slice[u8](*elt.data, elt.start + 4u, elt.end)) {
            result += ~[ebmlivec::doc_at(d.data, pos)];
        }
    }
    ret result;
}

fn maybe_find_item(item_id: int, items: &ebmlivec::doc) ->
   option::t[ebmlivec::doc] {
    fn eq_item(bytes: &u8[], item_id: int) -> bool {
        ret ebmlivec::be_uint_from_bytes(@bytes, 0u, 4u) as int == item_id;
    }
    let eqer = bind eq_item(_, item_id);
    let found = lookup_hash(items, eqer, hash_node_id(item_id));
    if ivec::len(found) == 0u {
        ret option::none[ebmlivec::doc];
    } else { ret option::some[ebmlivec::doc](found.(0)); }
}

fn find_item(item_id: int, items: &ebmlivec::doc) -> ebmlivec::doc {
    ret option::get(maybe_find_item(item_id, items));
}

// Looks up an item in the given metadata and returns an ebmlivec doc pointing
// to the item data.
fn lookup_item(item_id: int, data: &@u8[]) -> ebmlivec::doc {
    let items = ebmlivec::get_doc(ebmlivec::new_doc(data), tag_items);
    ret find_item(item_id, items);
}

fn item_family(item: &ebmlivec::doc) -> u8 {
    let fam = ebmlivec::get_doc(item, tag_items_data_item_family);
    ret ebmlivec::doc_as_uint(fam) as u8;
}

fn item_symbol(item: &ebmlivec::doc) -> str {
    let sym = ebmlivec::get_doc(item, tag_items_data_item_symbol);
    ret str::unsafe_from_bytes_ivec(ebmlivec::doc_data(sym));
}

fn variant_tag_id(d: &ebmlivec::doc) -> ast::def_id {
    let tagdoc = ebmlivec::get_doc(d, tag_items_data_item_tag_id);
    ret parse_def_id(ebmlivec::doc_data(tagdoc));
}

fn item_type(item: &ebmlivec::doc, this_cnum: ast::crate_num, tcx: ty::ctxt,
             extres: &external_resolver) -> ty::t {
    fn parse_external_def_id(this_cnum: ast::crate_num,
                             extres: &external_resolver, s: str) ->
       ast::def_id {
        let buf = str::bytes_ivec(s);
        let external_def_id = parse_def_id(buf);


        // This item was defined in the crate we're searching if it's has the
        // local crate number, otherwise we need to search a different crate
        if external_def_id.crate == ast::local_crate {
            ret {crate: this_cnum, node: external_def_id.node};
        } else { ret extres(external_def_id); }
    }
    let tp = ebmlivec::get_doc(item, tag_items_data_item_type);
    let def_parser = bind parse_external_def_id(this_cnum, extres, _);
    ret parse_ty_data(item.data, this_cnum, tp.start, tp.end - tp.start,
                      def_parser, tcx);
}

fn item_ty_param_kinds(item: &ebmlivec::doc) -> ast::kind[] {
    let ks: ast::kind[] = ~[];
    let tp = tag_items_data_item_ty_param_kinds;
    for each p: ebmlivec::doc in ebmlivec::tagged_docs(item, tp) {
        let dat : u8[] = ebmlivec::doc_data(p);
        let vi = ebmlivec::vint_at(dat, 0u);
        let i = 0u;
        while i < vi.val {
            let k = alt dat.(vi.next + i) as char {
              'u' { ast::kind_unique }
              's' { ast::kind_shared }
              'p' { ast::kind_pinned }
            };
            ks += ~[k];
            i += 1u;
        }
    }
    ret ks;
}

fn tag_variant_ids(item: &ebmlivec::doc, this_cnum: ast::crate_num) ->
   ast::def_id[] {
    let ids: ast::def_id[] = ~[];
    let v = tag_items_data_item_variant;
    for each p: ebmlivec::doc  in ebmlivec::tagged_docs(item, v) {
        let ext = parse_def_id(ebmlivec::doc_data(p));
        ids += ~[{crate: this_cnum, node: ext.node}];
    }
    ret ids;
}

// Given a path and serialized crate metadata, returns the ID of the
// definition the path refers to.
fn resolve_path(path: &ast::ident[], data: @u8[]) -> ast::def_id[] {
    fn eq_item(data: &u8[], s: str) -> bool {
        ret str::eq(str::unsafe_from_bytes_ivec(data), s);
    }
    let s = str::connect_ivec(path, "::");
    let md = ebmlivec::new_doc(data);
    let paths = ebmlivec::get_doc(md, tag_paths);
    let eqer = bind eq_item(_, s);
    let result: ast::def_id[] = ~[];
    for doc: ebmlivec::doc  in lookup_hash(paths, eqer, hash_path(s)) {
        let did_doc = ebmlivec::get_doc(doc, tag_def_id);
        result += ~[parse_def_id(ebmlivec::doc_data(did_doc))];
    }
    ret result;
}

// Crate metadata queries
fn lookup_defs(data: &@u8[], cnum: ast::crate_num, path: &ast::ident[]) ->
   ast::def[] {
    ret ivec::map(bind lookup_def(cnum, data, _), resolve_path(path, data));
}


// FIXME doesn't yet handle re-exported externals
fn lookup_def(cnum: ast::crate_num, data: @u8[], did_: &ast::def_id) ->
   ast::def {
    let item = lookup_item(did_.node, data);
    let fam_ch = item_family(item);
    let did = {crate: cnum, node: did_.node};
    // We treat references to tags as references to types.
    let def =
        alt fam_ch as char {
          'c' { ast::def_const(did) }
          'f' { ast::def_fn(did, ast::impure_fn) }
          'p' { ast::def_fn(did, ast::pure_fn) }
          'F' { ast::def_native_fn(did) }
          'y' { ast::def_ty(did) }
          'T' { ast::def_native_ty(did) }
          't' { ast::def_ty(did) }
          'm' { ast::def_mod(did) }
          'n' { ast::def_native_mod(did) }
          'v' {
            let tid = variant_tag_id(item);
            tid = {crate: cnum, node: tid.node};
            ast::def_variant(tid, did)
          }
        };
    ret def;
}

fn get_type(data: @u8[], def: ast::def_id, tcx: &ty::ctxt,
            extres: &external_resolver) -> ty::ty_param_kinds_and_ty {
    let this_cnum = def.crate;
    let node_id = def.node;
    let item = lookup_item(node_id, data);
    let t = item_type(item, this_cnum, tcx, extres);
    let tp_kinds : ast::kind[];
    let fam_ch = item_family(item);
    let has_ty_params = family_has_type_params(fam_ch);
    if has_ty_params {
        tp_kinds = item_ty_param_kinds(item);
    } else { tp_kinds = ~[]; }
    ret {kinds: tp_kinds, ty: t};
}

fn get_type_param_count(data: @u8[], id: ast::node_id) -> uint {
    ret ivec::len(get_type_param_kinds(data, id));
}

fn get_type_param_kinds(data: @u8[], id: ast::node_id) -> ast::kind[] {
    ret item_ty_param_kinds(lookup_item(id, data));
}

fn get_symbol(data: @u8[], id: ast::node_id) -> str {
    ret item_symbol(lookup_item(id, data));
}

fn get_tag_variants(data: &@u8[], def: ast::def_id, tcx: &ty::ctxt,
                    extres: &external_resolver) -> ty::variant_info[] {
    let external_crate_id = def.crate;
    let data =
        cstore::get_crate_data(tcx.sess.get_cstore(), external_crate_id).data;
    let items = ebmlivec::get_doc(ebmlivec::new_doc(data), tag_items);
    let item = find_item(def.node, items);
    let infos: ty::variant_info[] = ~[];
    let variant_ids = tag_variant_ids(item, external_crate_id);
    for did: ast::def_id  in variant_ids {
        let item = find_item(did.node, items);
        let ctor_ty = item_type(item, external_crate_id, tcx, extres);
        let arg_tys: ty::t[] = ~[];
        alt ty::struct(tcx, ctor_ty) {
          ty::ty_fn(_, args, _, _, _) {
            for a: ty::arg  in args { arg_tys += ~[a.ty]; }
          }
          _ {
            // Nullary tag variant.

          }
        }
        infos += ~[{args: arg_tys, ctor_ty: ctor_ty, id: did}];
    }
    ret infos;
}

fn family_has_type_params(fam_ch: u8) -> bool {
    ret alt fam_ch as char {
          'c' { false }
          'f' { true }
          'p' { true }
          'F' { true }
          'y' { true }
          't' { true }
          'T' { false }
          'm' { false }
          'n' { false }
          'v' { true }
        };
}

fn read_path(d: &ebmlivec::doc) -> {path: str, pos: uint} {
    let desc = ebmlivec::doc_data(d);
    let pos = ebmlivec::be_uint_from_bytes(@desc, 0u, 4u);
    let pathbytes = ivec::slice[u8](desc, 4u, ivec::len[u8](desc));
    let path = str::unsafe_from_bytes_ivec(pathbytes);
    ret {path: path, pos: pos};
}

fn describe_def(items: &ebmlivec::doc, id: ast::def_id) -> str {
    if id.crate != ast::local_crate { ret "external"; }
    ret item_family_to_str(item_family(find_item(id.node, items)));
}

fn item_family_to_str(fam: u8) -> str {
    alt fam as char {
      'c' { ret "const"; }
      'f' { ret "fn"; }
      'p' { ret "pred"; }
      'F' { ret "native fn"; }
      'y' { ret "type"; }
      'T' { ret "native type"; }
      't' { ret "type"; }
      'm' { ret "mod"; }
      'n' { ret "native mod"; }
      'v' { ret "tag"; }
    }
}

fn get_meta_items(md: &ebmlivec::doc) -> (@ast::meta_item)[] {
    let items: (@ast::meta_item)[] = ~[];
    for each meta_item_doc: ebmlivec::doc  in
             ebmlivec::tagged_docs(md, tag_meta_item_word) {
        let nd = ebmlivec::get_doc(meta_item_doc, tag_meta_item_name);
        let n = str::unsafe_from_bytes_ivec(ebmlivec::doc_data(nd));
        items += ~[attr::mk_word_item(n)];
    }
    for each meta_item_doc: ebmlivec::doc  in
             ebmlivec::tagged_docs(md, tag_meta_item_name_value) {
        let nd = ebmlivec::get_doc(meta_item_doc, tag_meta_item_name);
        let vd = ebmlivec::get_doc(meta_item_doc, tag_meta_item_value);
        let n = str::unsafe_from_bytes_ivec(ebmlivec::doc_data(nd));
        let v = str::unsafe_from_bytes_ivec(ebmlivec::doc_data(vd));
        // FIXME (#611): Should be able to decode meta_name_value variants,
        // but currently they can't be encoded
        items += ~[attr::mk_name_value_item_str(n, v)];
    }
    for each meta_item_doc: ebmlivec::doc  in
             ebmlivec::tagged_docs(md, tag_meta_item_list) {
        let nd = ebmlivec::get_doc(meta_item_doc, tag_meta_item_name);
        let n = str::unsafe_from_bytes_ivec(ebmlivec::doc_data(nd));
        let subitems = get_meta_items(meta_item_doc);
        items += ~[attr::mk_list_item(n, subitems)];
    }
    ret items;
}

fn get_attributes(md: &ebmlivec::doc) -> ast::attribute[] {
    let attrs: ast::attribute[] = ~[];
    alt ebmlivec::maybe_get_doc(md, tag_attributes) {
      option::some(attrs_d) {
        for each attr_doc: ebmlivec::doc  in
                 ebmlivec::tagged_docs(attrs_d, tag_attribute) {
            let meta_items = get_meta_items(attr_doc);
            // Currently it's only possible to have a single meta item on
            // an attribute
            assert (ivec::len(meta_items) == 1u);
            let meta_item = meta_items.(0);
            attrs +=
                ~[{node: {style: ast::attr_outer, value: *meta_item},
                   span: {lo: 0u, hi: 0u}}];
        }
      }
      option::none. { }
    }
    ret attrs;
}

fn list_meta_items(meta_items: &ebmlivec::doc, out: ioivec::writer) {
    for mi: @ast::meta_item  in get_meta_items(meta_items) {
        out.write_str(#fmt("%s\n", pprust::meta_item_to_str(*mi)));
    }
}

fn list_crate_attributes(md: &ebmlivec::doc, out: ioivec::writer) {
    out.write_str("=Crate Attributes=\n");

    for attr: ast::attribute  in get_attributes(md) {
        out.write_str(#fmt("%s\n", pprust::attribute_to_str(attr)));
    }

    out.write_str("\n\n");
}

fn get_crate_attributes(data: @u8[]) -> ast::attribute[] {
    ret get_attributes(ebmlivec::new_doc(data));
}

type crate_dep = {cnum: ast::crate_num, ident: str};

fn get_crate_deps(data: @u8[]) -> crate_dep[] {
    let deps: crate_dep[] = ~[];
    let cratedoc = ebmlivec::new_doc(data);
    let depsdoc = ebmlivec::get_doc(cratedoc, tag_crate_deps);
    let crate_num = 1;
    for each depdoc: ebmlivec::doc  in
             ebmlivec::tagged_docs(depsdoc, tag_crate_dep) {
        let depname = str::unsafe_from_bytes_ivec(ebmlivec::doc_data(depdoc));
        deps += ~[{cnum: crate_num, ident: depname}];
        crate_num += 1;
    }
    ret deps;
}

fn list_crate_deps(data: @u8[], out: ioivec::writer) {
    out.write_str("=External Dependencies=\n");

    for dep: crate_dep  in get_crate_deps(data) {
        out.write_str(#fmt("%d %s\n", dep.cnum, dep.ident));
    }

    out.write_str("\n");
}

fn list_crate_items(bytes: &@u8[], md: &ebmlivec::doc, out: ioivec::writer) {
    out.write_str("=Items=\n");
    let paths = ebmlivec::get_doc(md, tag_paths);
    let items = ebmlivec::get_doc(md, tag_items);
    let index = ebmlivec::get_doc(paths, tag_index);
    let bs = ebmlivec::get_doc(index, tag_index_buckets);
    for each bucket: ebmlivec::doc  in
             ebmlivec::tagged_docs(bs, tag_index_buckets_bucket) {
        let et = tag_index_buckets_bucket_elt;
        for each elt: ebmlivec::doc  in ebmlivec::tagged_docs(bucket, et) {
            let data = read_path(elt);
            let def = ebmlivec::doc_at(bytes, data.pos);
            let did_doc = ebmlivec::get_doc(def, tag_def_id);
            let did = parse_def_id(ebmlivec::doc_data(did_doc));
            out.write_str(#fmt("%s (%s)\n", data.path,
                               describe_def(items, did)));
        }
    }
    out.write_str("\n");
}

fn list_crate_metadata(bytes: &@u8[], out: ioivec::writer) {
    let md = ebmlivec::new_doc(bytes);
    list_crate_attributes(md, out);
    list_crate_deps(bytes, out);
    list_crate_items(bytes, md, out);
}

// Local Variables:
// mode: rust
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// compile-command: "make -k -C $RBUILD 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
// End: