/*
Open Asset Import Library (assimp)
----------------------------------------------------------------------

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  following disclaimer.

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*/

/** @file  STEPFileReader.cpp
 *  @brief Implementation of the STEP file parser, which fills a
 *     STEP::DB with data read from a file.
 */

#include "STEPFileReader.h"
#include "STEPFileEncoding.h"
#include <assimp/TinyFormatter.h>
#include <assimp/fast_atof.h>
#include <memory>
#include <functional>

using namespace Assimp;

namespace EXPRESS = STEP::EXPRESS;

// ------------------------------------------------------------------------------------------------
std::string AddLineNumber(const std::string& s,uint64_t line /*= LINE_NOT_SPECIFIED*/, const std::string& prefix = "")
{
    return line == STEP::SyntaxError::LINE_NOT_SPECIFIED ? prefix+s : static_cast<std::string>( (Formatter::format(),prefix,"(line ",line,") ",s) );
}

// ------------------------------------------------------------------------------------------------
std::string AddEntityID(const std::string& s,uint64_t entity /*= ENTITY_NOT_SPECIFIED*/, const std::string& prefix = "")
{
    return entity == STEP::TypeError::ENTITY_NOT_SPECIFIED ? prefix+s : static_cast<std::string>( (Formatter::format(),prefix,"(entity #",entity,") ",s));
}


// ------------------------------------------------------------------------------------------------
STEP::SyntaxError::SyntaxError (const std::string& s,uint64_t line /* = LINE_NOT_SPECIFIED */)
: DeadlyImportError(AddLineNumber(s,line))
{

}

// ------------------------------------------------------------------------------------------------
STEP::TypeError::TypeError (const std::string& s,uint64_t entity /* = ENTITY_NOT_SPECIFIED */,uint64_t line /*= LINE_NOT_SPECIFIED*/)
: DeadlyImportError(AddLineNumber(AddEntityID(s,entity),line))
{

}

static const char *ISO_Token         = "ISO-10303-21;";
static const char *FILE_SCHEMA_Token = "FILE_SCHEMA";
// ------------------------------------------------------------------------------------------------
STEP::DB* STEP::ReadFileHeader(std::shared_ptr<IOStream> stream) {
    std::shared_ptr<StreamReaderLE> reader = std::shared_ptr<StreamReaderLE>(new StreamReaderLE(stream));
    std::unique_ptr<STEP::DB> db = std::unique_ptr<STEP::DB>(new STEP::DB(reader));

    LineSplitter &splitter = db->GetSplitter();
    if (!splitter || *splitter != ISO_Token ) {
        throw STEP::SyntaxError("expected magic token: " + std::string( ISO_Token ), 1);
    }

    HeaderInfo& head = db->GetHeader();
    for(++splitter; splitter; ++splitter) {
        const std::string& s = *splitter;
        if (s == "DATA;") {
            // here we go, header done, start of data section
            ++splitter;
            break;
        }

        // want one-based line numbers for human readers, so +1
        const uint64_t line = splitter.get_index()+1;

        if (s.substr(0,11) == FILE_SCHEMA_Token) {
            const char* sz = s.c_str()+11;
            SkipSpaces(sz,&sz);
            std::shared_ptr< const EXPRESS::DataType > schema = EXPRESS::DataType::Parse(sz);

            // the file schema should be a regular list entity, although it usually contains exactly one entry
            // since the list itself is contained in a regular parameter list, we actually have
            // two nested lists.
            const EXPRESS::LIST* list = dynamic_cast<const EXPRESS::LIST*>(schema.get());
            if (list && list->GetSize()) {
                list = dynamic_cast<const EXPRESS::LIST*>( (*list)[0].get() );
                if (!list) {
                    throw STEP::SyntaxError("expected FILE_SCHEMA to be a list",line);
                }

                // XXX need support for multiple schemas?
                if (list->GetSize() > 1)    {
                    ASSIMP_LOG_WARN(AddLineNumber("multiple schemas currently not supported",line));
                }
                const EXPRESS::STRING *string = dynamic_cast<const EXPRESS::STRING *>((*list)[0].get());
                if (!list->GetSize() || nullptr == string ) {
                    throw STEP::SyntaxError("expected FILE_SCHEMA to contain a single string literal",line);
                }
                head.fileSchema =  *string;
            }
        }

        // XXX handle more header fields
    }

    return db.release();
}


namespace {

// ------------------------------------------------------------------------------------------------
// check whether the given line contains an entity definition (i.e. starts with "#<number>=")
bool IsEntityDef(const std::string& snext)
{
    if (snext[0] == '#') {
        // it is only a new entity if it has a '=' after the
        // entity ID.
        for(std::string::const_iterator it = snext.begin()+1; it != snext.end(); ++it) {
            if (*it == '=') {
                return true;
            }
            if ((*it < '0' || *it > '9') && *it != ' ') {
                break;
            }
        }
    }
    return false;
}

}


// ------------------------------------------------------------------------------------------------
void STEP::ReadFile(DB& db,const EXPRESS::ConversionSchema& scheme,
    const char* const* types_to_track, size_t len,
    const char* const* inverse_indices_to_track, size_t len2)
{
    db.SetSchema(scheme);
    db.SetTypesToTrack(types_to_track,len);
    db.SetInverseIndicesToTrack(inverse_indices_to_track,len2);

    const DB::ObjectMap& map = db.GetObjects();
    LineSplitter& splitter = db.GetSplitter();

    while (splitter) {
        bool has_next = false;
        std::string s = *splitter;
        if (s == "ENDSEC;") {
            break;
        }
        s.erase(std::remove(s.begin(), s.end(), ' '), s.end());

        // want one-based line numbers for human readers, so +1
        const uint64_t line = splitter.get_index()+1;
        // LineSplitter already ignores empty lines
        ai_assert(s.length());
        if (s[0] != '#') {
            ASSIMP_LOG_WARN(AddLineNumber("expected token \'#\'",line));
            ++splitter;
            continue;
        }
        // ---
        // extract id, entity class name and argument string,
        // but don't create the actual object yet.
        // ---
        const std::string::size_type n0 = s.find_first_of('=');
        if (n0 == std::string::npos) {
            ASSIMP_LOG_WARN(AddLineNumber("expected token \'=\'",line));
            ++splitter;
            continue;
        }

        const uint64_t id = strtoul10_64(s.substr(1,n0-1).c_str());
        if (!id) {
            ASSIMP_LOG_WARN(AddLineNumber("expected positive, numeric entity id",line));
            ++splitter;
            continue;
        }
        std::string::size_type n1 = s.find_first_of('(',n0);
        if (n1 == std::string::npos) {
            has_next = true;
            bool ok = false;
            for( ++splitter; splitter; ++splitter) {
                const std::string& snext = *splitter;
                if (snext.empty()) {
                    continue;
                }

                // the next line doesn't start an entity, so maybe it is
                // just a continuation  for this line, keep going
                if (!IsEntityDef(snext)) {
                    s.append(snext);
                    n1 = s.find_first_of('(',n0);
                    ok = (n1 != std::string::npos);
                }
                else {
                    break;
                }
            }

            if(!ok) {
                ASSIMP_LOG_WARN(AddLineNumber("expected token \'(\'",line));
                continue;
            }
        }

        std::string::size_type n2 = s.find_last_of(')');
        if (n2 == std::string::npos || n2 < n1 || n2 == s.length() - 1 || s[n2 + 1] != ';') {
            has_next = true;
            bool ok = false;
            for( ++splitter; splitter; ++splitter) {
                const std::string& snext = *splitter;
                if (snext.empty()) {
                    continue;
                }

                // the next line doesn't start an entity, so maybe it is
                // just a continuation  for this line, keep going
                if (!IsEntityDef(snext)) {
                    s.append(snext);
                    n2 = s.find_last_of(')');
                    ok = !(n2 == std::string::npos || n2 < n1 || n2 == s.length() - 1 || s[n2 + 1] != ';');
                } else {
                    break;
                }
            }
            if(!ok) {
                ASSIMP_LOG_WARN(AddLineNumber("expected token \')\'",line));
                continue;
            }
        }

        if (map.find(id) != map.end()) {
            ASSIMP_LOG_WARN(AddLineNumber((Formatter::format(),"an object with the id #",id," already exists"),line));
        }

        std::string::size_type ns = n0;
        do ++ns; while( IsSpace(s.at(ns)));
        std::string::size_type ne = n1;
        do --ne; while( IsSpace(s.at(ne)));
        std::string type = s.substr(ns,ne-ns+1);
        std::transform( type.begin(), type.end(), type.begin(), &Assimp::ToLower<char>  );
        const char* sz = scheme.GetStaticStringForToken(type);
        if(sz) {
            const std::string::size_type szLen = n2-n1+1;
            char* const copysz = new char[szLen+1];
            std::copy(s.c_str()+n1,s.c_str()+n2+1,copysz);
            copysz[szLen] = '\0';
            db.InternInsert(new LazyObject(db,id,line,sz,copysz));
        }
        if(!has_next) {
            ++splitter;
        }
    }

    if (!splitter) {
        ASSIMP_LOG_WARN("STEP: ignoring unexpected EOF");
    }

    if ( !DefaultLogger::isNullLogger()){
        ASSIMP_LOG_DEBUG((Formatter::format(),"STEP: got ",map.size()," object records with ",
            db.GetRefs().size()," inverse index entries"));
    }
}

// ------------------------------------------------------------------------------------------------
std::shared_ptr<const EXPRESS::DataType> EXPRESS::DataType::Parse(const char*& inout,uint64_t line, const EXPRESS::ConversionSchema* schema /*= nullptr*/)
{
    const char* cur = inout;
    SkipSpaces(&cur);
    if (*cur == ',' || IsSpaceOrNewLine(*cur)) {
        throw STEP::SyntaxError("unexpected token, expected parameter",line);
    }

    // just skip over constructions such as IFCPLANEANGLEMEASURE(0.01) and read only the value
    if (schema) {
        bool ok = false;
        for(const char* t = cur; *t && *t != ')' && *t != ','; ++t) {
            if (*t=='(') {
                if (!ok) {
                    break;
                }
                for(--t;IsSpace(*t);--t);
                std::string s(cur,static_cast<size_t>(t-cur+1));
                std::transform(s.begin(),s.end(),s.begin(),&ToLower<char> );
                if (schema->IsKnownToken(s)) {
                    for(cur = t+1;*cur++ != '(';);
                    const std::shared_ptr<const EXPRESS::DataType> dt = Parse(cur);
                    inout = *cur ? cur+1 : cur;
                    return dt;
                }
                break;
            }
            else if (!IsSpace(*t)) {
                ok = true;
            }
        }
    }

    if (*cur == '*' ) {
        inout = cur+1;
        return std::make_shared<EXPRESS::ISDERIVED>();
    }
    else if (*cur == '$' ) {
        inout = cur+1;
        return std::make_shared<EXPRESS::UNSET>();
    }
    else if (*cur == '(' ) {
        // start of an aggregate, further parsing is done by the LIST factory constructor
        inout = cur;
        return EXPRESS::LIST::Parse(inout,line,schema);
    }
    else if (*cur == '.' ) {
        // enum (includes boolean)
        const char* start = ++cur;
        for(;*cur != '.';++cur) {
            if (*cur == '\0') {
                throw STEP::SyntaxError("enum not closed",line);
            }
        }
        inout = cur+1;
        return std::make_shared<EXPRESS::ENUMERATION>(std::string(start, static_cast<size_t>(cur-start) ));
    }
    else if (*cur == '#' ) {
        // object reference
        return std::make_shared<EXPRESS::ENTITY>(strtoul10_64(++cur,&inout));
    }
    else if (*cur == '\'' ) {
        // string literal
        const char* start = ++cur;

        for(;*cur != '\'';++cur)    {
            if (*cur == '\0')   {
                throw STEP::SyntaxError("string literal not closed",line);
            }
        }

        if (cur[1] == '\'') {
            // Vesanen: more than 2 escaped ' in one literal!
            do  {
                for(cur += 2;*cur != '\'';++cur)    {
                    if (*cur == '\0')   {
                        throw STEP::SyntaxError("string literal not closed",line);
                    }
                }
            }
            while(cur[1] == '\'');
        }

        inout = cur + 1;

        // assimp is supposed to output UTF8 strings, so we have to deal
        // with foreign encodings.
        std::string stemp = std::string(start, static_cast<size_t>(cur - start));
        if(!StringToUTF8(stemp)) {
            // TODO: route this to a correct logger with line numbers etc., better error messages
            ASSIMP_LOG_ERROR("an error occurred reading escape sequences in ASCII text");
        }

        return std::make_shared<EXPRESS::STRING>(stemp);
    }
    else if (*cur == '\"' ) {
        throw STEP::SyntaxError("binary data not supported yet",line);
    }

    // else -- must be a number. if there is a decimal dot in it,
    // parse it as real value, otherwise as integer.
    const char* start = cur;
    for(;*cur  && *cur != ',' && *cur != ')' && !IsSpace(*cur);++cur) {
        if (*cur == '.') {
            double f;
            inout = fast_atoreal_move<double>(start,f);
            return std::make_shared<EXPRESS::REAL>(f);
        }
    }

    bool neg = false;
    if (*start == '-') {
        neg = true;
        ++start;
    }
    else if (*start == '+') {
        ++start;
    }
    int64_t num = static_cast<int64_t>( strtoul10_64(start,&inout) );
    return std::make_shared<EXPRESS::INTEGER>(neg?-num:num);
}

// ------------------------------------------------------------------------------------------------
std::shared_ptr<const EXPRESS::LIST> EXPRESS::LIST::Parse(const char*& inout,uint64_t line, const EXPRESS::ConversionSchema* schema /*= nullptr*/) {
    const std::shared_ptr<EXPRESS::LIST> list = std::make_shared<EXPRESS::LIST>();
    EXPRESS::LIST::MemberList& members = list->members;

    const char* cur = inout;
    if (*cur++ != '(') {
        throw STEP::SyntaxError("unexpected token, expected \'(\' token at beginning of list",line);
    }

    // estimate the number of items upfront - lists can grow large
    size_t count = 1;
    for(const char* c=cur; *c && *c != ')'; ++c) {
        count += (*c == ',' ? 1 : 0);
    }

    members.reserve(count);

    for(;;++cur) {
        if (!*cur) {
            throw STEP::SyntaxError("unexpected end of line while reading list");
        }
        SkipSpaces(cur,&cur);
        if (*cur == ')') {
            break;
        }

        members.push_back( EXPRESS::DataType::Parse(cur,line,schema));
        SkipSpaces(cur,&cur);

        if (*cur != ',') {
            if (*cur == ')') {
                break;
            }
            throw STEP::SyntaxError("unexpected token, expected \',\' or \')\' token after list element",line);
        }
    }

    inout = cur+1;
    return list;
}

// ------------------------------------------------------------------------------------------------
static void handleSkippedDepthFromToken(const char *a, int64_t &skip_depth ) {
    if (*a == '(') {
        ++skip_depth;
    } else if (*a == ')') {
        --skip_depth;
    }
}

// ------------------------------------------------------------------------------------------------
static int64_t getIdFromToken(const char *a) {
    const char *tmp;
    const int64_t num = static_cast<int64_t>(strtoul10_64(a + 1, &tmp));

    return num;
}

// ------------------------------------------------------------------------------------------------
STEP::LazyObject::LazyObject(DB& db, uint64_t id,uint64_t /*line*/, const char* const type,const char* args)
: id(id)
, type(type)
, db(db)
, args(args)
, obj() {
    // find any external references and store them in the database.
    // this helps us emulate STEPs INVERSE fields.
    if (!db.KeepInverseIndicesForType(type)) {
        return;
    }

    // do a quick scan through the argument tuple and watch out for entity references
    const char *a( args );
    int64_t skip_depth( 0 );
    while ( *a ) {
        handleSkippedDepthFromToken(a, skip_depth);
        /*if (*a == '(') {
            ++skip_depth;
        } else if (*a == ')') {
            --skip_depth;
        }*/

		if (skip_depth >= 1 && *a=='#') {
			if (*(a + 1) != '#') {
				/*const char *tmp;
				const int64_t num = static_cast<int64_t>(strtoul10_64(a + 1, &tmp));
				db.MarkRef(num, id);*/
                db.MarkRef(getIdFromToken(a), id);
			} else {
				++a;
			}
        }
        ++a;
    }
}

// ------------------------------------------------------------------------------------------------
STEP::LazyObject::~LazyObject() {
    // make sure the right dtor/operator delete get called
    if (obj) {
        delete obj;
    } else {
        delete[] args;
    }
}

// ------------------------------------------------------------------------------------------------
void STEP::LazyObject::LazyInit() const {
    const EXPRESS::ConversionSchema& schema = db.GetSchema();
    STEP::ConvertObjectProc proc = schema.GetConverterProc(type);

    if (!proc) {
        throw STEP::TypeError("unknown object type: " + std::string(type),id);
    }

    const char* acopy = args;
    std::shared_ptr<const EXPRESS::LIST> conv_args = EXPRESS::LIST::Parse(acopy,(uint64_t)STEP::SyntaxError::LINE_NOT_SPECIFIED,&db.GetSchema());
    delete[] args;
    args = nullptr;

    // if the converter fails, it should throw an exception, but it should never return nullptr
    try {
        obj = proc(db,*conv_args);
    }
    catch(const TypeError& t) {
        // augment line and entity information
        throw TypeError(t.what(),id);
    }
    ++db.evaluated_count;
    ai_assert(obj);

    // store the original id in the object instance
    obj->SetID(id);
}
