/***
    Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: Parser.hpp
    Date: 2021-6-9
    Author: Reece
***/
#pragma once

#include <Aurora/Data/Data.hpp>
#include <Aurora/IO/Character/ICharacterProvider.hpp>
#include <Aurora/IO/Character/ICharacterProviderEx.hpp>
#include <Aurora/IO/Character/IBufferedCharacterConsumer.hpp>
#include <Aurora/IO/Character/Providers.hpp>

namespace Aurora::Parse
{
    enum class ParsableTag
    {
        kParseUInt    = (const int)Data::EDataType::kTypeUInt,
        kParseSInt    = (const int)Data::EDataType::kTypeSInt,
        kParseNumber  = (const int)Data::EDataType::kTypeNumber,
        kParseString  = (const int)Data::EDataType::kTypeString,
        kParseBoolean = (const int)Data::EDataType::kTypeBoolean,
        kParseUUID    = (const int)Data::EDataType::kTypeUUID,
        kParseVec3    = (const int)Data::EDataType::kTypeVec3,
        kParseVec4    = (const int)Data::EDataType::kTypeVec4,
        kParseObject,
        kParseStringVararg
    };

    struct ParseBit;
    struct ParsedBit;
    using ParseObject = AuList<ParseBit>;
    using ParsedObject = AuList<ParsedBit>;

    using ParsePrimativeValue = Data::PrimitiveValue;
    using ParseValue = Data::Value;

    struct ParseValueEx : ParseValue
    {
        ParsedObject object;
    };

    struct ParseBit
    {
        ParseBit(const ParseBit &in) = default;

        ParseBit(ParsableTag tag, const AuString &label) : tag(tag), label(label)
        {}

        ParseBit(ParsableTag tag, const AuString &label, bool array, bool optional, bool _vararg) : tag(tag), label(label), array(array), optional(optional), vararg(_vararg)
        {}

        ParseBit(ParsableTag tag) : tag(tag)
        {}

        ParseBit(ParsableTag tag, bool array, bool optional, bool _vararg) : tag(tag), array(array), optional(optional), vararg(_vararg)
        {}

        ParseBit(ParseObject _ObjectParse) : tag(ParsableTag::kParseObject), objectParse(_ObjectParse)
        {}

        ParseBit(ParseObject _ObjectParse, const AuString &label) : tag(ParsableTag::kParseObject), objectParse(_ObjectParse), label(label)
        {}

        // marks this "parse bit" and all following part bits optional 
        bool optional = false;

        // if true, the lexer yoinks a length prefix token before iterating over array length 
        bool array = false;

        // if true, the lexer parses tag or object parse until EOS
        bool vararg = false;

        // parse defintion
        ParsableTag tag;
        ParseObject objectParse;

        // optional:
        AuString label = "";

        // parse object
        //    {...}
        // single parse bit:
        //    <tag-label: value>
        // optional:
        //    <max-number: value> <min-number: value> (<min-number: value>)
        // var arg:
        //    <max-number: value> <min-number: value> (<min-number: value> ...)
        // arrays
        //    <max-number: value> <min-number: value> [<array count> <min-number: value>]
    };

    struct ParsedBit
    {
        inline ParsedBit()
        {}
        
        inline ParsedBit(ParsableTag tag) : tag(tag)
        {}

        AuMach count {};
        ParsableTag tag;
        bool isArray {};

        struct
        {
            ParseValueEx single;
            AuList<ParseValueEx> array;
        } value;
    };

    struct ParseResult
    {
        AuString syntaxError;
        AuString debugTree;
        ParsedObject result;
    };

#if 0
    using ConsumeStream_cb = AuFunction<bool(AuUInt8 &)>;

    static ConsumeStream_cb StringToConsumable(const AuString &str, AuMach &index)
    {
        auto getc = [&](AuUInt8 &byt) mutable
        {
            if (index == str.length())
            {
                return false;
            }
            byt = str[index];
            index++;
            return true;
        };
        return getc;
    }
#endif

  
    struct ParseState
    {
        ParseState(const AuSPtr<Aurora::IO::Character::ICharacterProvider> &stream) : stream(stream)
        {}

        AuSPtr<Aurora::IO::Character::ICharacterProvider> stream;

        AuUInt8 *additionalTokens {};
        AuUInt16 countOfTokens {};
      
        bool hasLastToken {};
        AuUInt8 lastTokenCharacter {};
        AuMach lastTokenAdditional {};
    };

    AUKN_SYM void VaildateStructure(const ParseObject &object);
    AUKN_SYM bool ConsumeToken(ParsableTag type, const AuSPtr<Aurora::IO::Character::ICharacterProvider> &getc, ParseValue &out);

    static bool ConsumeToken(ParsableTag type, const AuString &str, AuMach &index, ParseValueEx &out)
    {
        auto strStream = IO::Character::ProviderFromStringUnique(str, index);
        if (!strStream) return false;
        if (!ConsumeToken(type, AuUnsafeRaiiToShared(strStream), out)) return false;
        index = strStream->GetPosition();
        return true;
    }

    static bool ConsumeToken(ParsableTag type, const AuString &str, ParseValueEx &out)
    {
        auto strStream = IO::Character::ProviderFromStringUnique(str);
        if (!strStream) return false;
        return ConsumeToken(type, AuUnsafeRaiiToShared(strStream), out);
    }

    AUKN_SYM bool Parse(ParseState &state, const ParseObject &structure, ParseResult &result);

    static bool Parse(ParseResult &result, const ParseObject &structure, const AuString &str, AuMach &index)
    {
        auto strStream = IO::Character::ProviderFromStringUnique(str, index);
        if (!strStream) return false;
        ParseState state(AuUnsafeRaiiToShared(strStream));
        if (!Parse(state, structure, result)) return false;
        index = strStream->GetPosition();
        return true;
    }

    static bool Parse(ParseResult &result, const ParseObject &structure, const AuString &str)
    {
        auto strStream = IO::Character::ProviderFromStringUnique(str, 0);
        if (!strStream) return false;
        ParseState state(AuUnsafeRaiiToShared(strStream));
        return Parse(state, structure, result);
    }

    AUKN_SYM void SerializeToken(ParsableTag type, const ParseValue &value, AuString &str);
    AUKN_SYM void Serialize(const ParsedObject &structure, AuString &ret);

    AUKN_SYM AuResult<AuSInt> ParseSInt(const char *begin, const char *&end);
    AUKN_SYM AuResult<AuUInt> ParseUInt(const char *begin, const char *&end);
}