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

    File: Parser.cpp
    Date: 2021-6-12
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "Parser.hpp"

namespace Aurora::Parse
{
    AUKN_SYM void VaildateStructure(const ParseObject &object)
    {
    }

    struct ParseContext
    {
        AuUInt8 _next;
        bool _hasNext;
        const ConsumeStream_cb &_getc;

        ParseContext(const ConsumeStream_cb &getc) : _getc(getc), _next(0), _hasNext(false)
        {
        }

        bool Next(AuUInt8 &c)
        {
            if (AuExchange(_hasNext, false))
            {
                c = _next;
                return true;
            }

            return _getc(c);
        }

        bool Peek(AuUInt8 &c)
        {
            if (_hasNext)
            {
                c = _next;
                return true;
            }

            _hasNext = _getc(_next);
            c = _next;
            return _hasNext;
        }
    };

    template<size_t Z>
    static AuFunction<bool(AuUInt8)> ContainedHerein(const AuUInt8(&arry)[Z])
    {
        return [=](AuUInt8 c) -> bool
        {
            for (int i = 0; i < Z; i++)
            {
                if (arry[i] == c)
                {
                    return true;
                }
            }
            return false;
        };
    }
    

    template<size_t Z>
    static AuFunction<bool(AuUInt8)> IsTerminating(ParseState &state, const AuUInt8(&arry)[Z])
    {
        return [&](AuUInt8 c) -> bool
        {
            for (int i = 0; i < Z; i++)
            {
                if (arry[i] == c)
                {
                    return true;
                }
            }

            for (int i = 0; i < state.countOfTokens; i++)
            {
                if (state.additionalTokens[i] == c)
                {
                    state.lastTokenAdditional = i;
                    return true;
                }
            }
            return false;
        };
    }

    // oh god just dont think about this tokenizer too much
    bool ConsumeStringifedToken(ParseState &state, ParseContext &context, ParsableTag type, AuString &out)
    {
        static unsigned char terminatingChars[] = { '\n', '\00' };
        static unsigned char whiteChars[] = { ' ' };
        static unsigned char illegalCharacters[] = { '\r' }; //reeedows 

        auto isString = type == ParsableTag::kParseString;
        auto isvararg = type == ParsableTag::kParseStringVararg;
        bool stringLevel = false;
        bool escapedNewLine = false;
        bool escapedQuote = false;

        auto isTerminating = IsTerminating(state, terminatingChars);
        static auto isSpace = ContainedHerein(whiteChars);
        static auto isIgnore = ContainedHerein(illegalCharacters);

        while (true)
        {
            AuUInt8 next;
            AuUInt8 peek;

            // consume character from the stream 
            if (!context.Next(next))
            {
                break;
            }

            // some characters should be considered universally illegal such as nasty unicode spaces,
            // carriage returns, and any other nasty crash exploit depending characters
            // DO NOT USE THIS TO ESCAPE ENGINE TAGS/COLOR ESCAPES/WHATEVER THE FUCK
            if (isIgnore(next))
            {
                continue;
            }

            // Is end of line/end of string
            if (isTerminating(next))
            {
                // Make sure we aren't encapsulated by quotation marks
                if ((!stringLevel) && (!AuExchange(escapedNewLine, false)))
                {
                    state.hasLastToken = true;
                    state.lastTokenCharacter = next;
                    break;
                }
            }

            // if we hit a space in a string, assume we're at the end of the token, unless we're parsing
            //  a string in quotation marks or are consuming the entire line (ParsableTag::kParseStringVararg) 
            if ((isSpace(next)) && (!stringLevel) && (!isvararg))
            {
                break;
            }

            // if the string starts with a quotation mark, set stringLevel to true 
            if ((next == '"') && (isString) && (out.empty()))
            {
                stringLevel = true;
                continue;
            }

            auto peekStatus = context.Peek(peek);

            bool isPeekterminating = isTerminating(peek);

            // check \ \n pair + is var arg
            if ((peekStatus) && (isPeekterminating) && (next == '\\') && (isvararg))
            {
                escapedNewLine = true;
                continue;
            }

            // escape character for "'s in strings 
            if ((peekStatus) && (isString) && (next == '\\') && (stringLevel) && (peek == '\"'))
            {
                escapedQuote = true;
                continue;
            }

            // see above
            if ((next == '"') && (isString) && (AuExchange(escapedQuote, false)))
            {
                out += "\"";
                continue;
            }
            // match the ending '"' character in the token to terminate strings containing spaces
            // do not make this more ambiguous by removing the  **else if**.
            // this is mutally exclusive with the above block and must be kept in this order
            else if (
                (next == '"') && (isString) && (stringLevel)  // 

                && (((peekStatus && (isPeekterminating || isSpace(peek))) || (!peekStatus)))) // expected to fail
            {
                stringLevel = false;
                continue;
            }

            // otherwise emit
            out += next;
        }

        //SysAssert(!stringLevel, "Parsed tag of string type must end with \", got {}", out);
        if (stringLevel)
        {
            LogWarn("Parsed tag of string type must end with \", got {}", out);
            return false;
        }

        //Aurora::Console::Logging::LogDbg("returned {} {}", out, count != 0);
        return out.size() != 0;
    }

    template<typename Func, typename Res>
    static bool ScrewExceptions_2(Func func, const AuString &in, Res &out)
    {
        try
        {
            out = func(in.c_str(), nullptr);
            return true;
        }
        catch (...)
        {
            return false;
        }
    }

    template <typename T> int SignBit(T val)
    {
        return (T(0) < val) - (val < T(0));
    }

    template <typename T>
    bool ParseInt(const AuString &in, T &out)
    {
        T res = 0;
        T sign = 1;
        out = 0;

        auto itr = in.begin();

        if constexpr (AuIsSame_v<T, AuSInt>)
        {
            if (itr != in.end())
            {
                if (*itr == '-')
                {
                    itr++;
                    sign = -1;
                }
            }
        }

        for (;
             (itr != in.end()) &&
             (*itr != '\0');
             itr++)
        {
            auto c = *itr;

            if ((c < '0') || (c > '9'))
            {
                return false;
            }

            auto old = res;

            res *= 10;
            res += static_cast<AuUInt>(*itr) - static_cast<AuUInt>('0');

            if constexpr (AuIsSame_v<T, AuUInt>)
            {
                if (old > res)
                {
                    SysPushErrorSyntaxError("Unsigned integer overflow: {}", in);
                    return false;
                }
            }
            else if constexpr (AuIsSame_v<T, AuSInt>)
            {
                if (SignBit(old) != SignBit(res))
                {
                    SysPushErrorSyntaxError("Signed integer overflow: {}", in);
                    return false;
                }
            }
        }

        out = res * sign;
        return true;
    }

    template <typename T>
    bool ParseUInt(const AuString &in, T &out)
    {
        auto temp = AuUInt{};
        out = 0;

        if (!ParseInt<AuUInt>(in, temp))
        {
            return false;
        }

        if (temp > std::numeric_limits<T>::max())
        {
            return false;
        }

        out = temp;
        return true;
    }

    template <typename T>
    bool ParseSInt(const AuString &in, T &out)
    {
        auto temp = AuSInt{};
        out = 0;

        if (!ParseInt<AuSInt>(in, temp))
        {
            return false;
        }

        if (temp > std::numeric_limits<T>::max())
        {
            return false;
        }

        if (temp < std::numeric_limits<T>::min())
        {
            return false;
        }

        out = temp;
        return true;
    }

    static bool ConsumeTokenPrimitiveish(ParseState &state, ParseContext &context, ParsableTag type, ParseValue &out)
    {
        AuString str;

        if (!ConsumeStringifedToken(state, context, type, str))
        {
            return false;
        }

        if ((type != ParsableTag::kParseString) && (str.empty()))
        {
            return false;
        }

        AuOptional<uuids::uuid> uuid;

        switch (type)
        {
        case ParsableTag::kParseUInt:
        {
            return ParseUInt(str, out.primitive.uint);
        }
        case ParsableTag::kParseSInt:
        {
            return ParseSInt(str, out.primitive.sint);
        }
        case ParsableTag::kParseNumber:
        {
            return ScrewExceptions_2(static_cast<double(&)(const std::string &, std::size_t *)>(std::stod), str, out.primitive.number);
        }
        case ParsableTag::kParseString:
        case ParsableTag::kParseStringVararg:
        {
            out.string = str;
            break;
        }
        case ParsableTag::kParseUUID:
        {
            uuid = uuids::uuid::from_string(str);
            if (!uuid.has_value())
            {
                LogWarn("Parse Error: invalid UUID {}", str);
                return false;
            }
            out.UUID = uuid.value();
            break;
        }
        case ParsableTag::kParseBoolean:
        {
            if ((str == "0") || (stricmp(str.c_str(), "false") == 0) || (stricmp(str.c_str(), "no") == 0))
            {
                out.primitive.boolean = false;
            }
            else if ((str == "1") || (stricmp(str.c_str(), "true") == 0) || (stricmp(str.c_str(), "yes") == 0))
            {
                out.primitive.boolean = true;
            }
            else
            {
                Aurora::Console::Logging::LogWarn("Parsed tag of boolean type wasn't parsable given the English string {}", str);
                return false;
            }
            break;
        }
        default:
            SysPanic("Invalid consume tag {}", type);
        }

        return true;
    }

    static bool ConsumeToken(ParseState &state, ParseContext &context, ParsableTag type, ParseValue &out)
    {
        ParseValue temp;

    #define ADD_VECTOR_VAL(idx, memberType)                                      \
            if (!ConsumeTokenPrimitiveish(state, context, ParsableTag::kParseNumber, temp)) \
                return false;                                                        \
            out.primitive.memberType[idx] = temp.primitive.number;

        switch (type)
        {
        case ParsableTag::kParseVec3:
        {
            ADD_VECTOR_VAL(0, vec3);
            ADD_VECTOR_VAL(1, vec3);
            ADD_VECTOR_VAL(2, vec3);
            return true;
        }
        case ParsableTag::kParseVec4:
        {
            ADD_VECTOR_VAL(0, vec4);
            ADD_VECTOR_VAL(1, vec4);
            ADD_VECTOR_VAL(2, vec4);
            ADD_VECTOR_VAL(3, vec4);
            return true;
        }
        default:
        {
            return ConsumeTokenPrimitiveish(state, context, type, out);
        }
        }

    #undef ADD_VECTOR_VAL
    }

    AUKN_SYM bool ConsumeToken(ParsableTag type, ConsumeStream_cb getc, ParseValue &out)
    {
        ParseState state(getc);
        ParseContext context(state.stringstream);
        return ConsumeToken(state, context, type, out);
    }

    static bool Parse(ParseState &state, ParseContext &context, const ParseObject &structure, ParseResult &result)
    {
        for (auto &parseBit : structure)
        {
            ParsedBit parsed = {};
            bool ok;

            parsed.tag = parseBit.tag;

            AuMach arrayLength = 1;
            if (parseBit.array)
            {
                ParseValue arrayLengthBit = {};

                if (!ConsumeToken(state, context, ParsableTag::kParseUInt, arrayLengthBit))
                {
                    Aurora::Console::Logging::LogWarn("Couldn't consume array length, label: {}, tag {}", parseBit.label, parseBit.tag);
                    return false;
                }

                arrayLength = arrayLengthBit.primitive.uint;
            }

            parsed.count = 0;

            for (int i = 0; ((i < arrayLength) || (parseBit.vararg)); i++)
            {
                ParseValueEx parsedSingle = {};
                ParseResult  nestedresult = {};
                switch (parseBit.tag)
                {
                case ParsableTag::kParseUInt:
                case ParsableTag::kParseSInt:
                case ParsableTag::kParseString:
                case ParsableTag::kParseStringVararg:
                case ParsableTag::kParseNumber:
                case ParsableTag::kParseBoolean:
                case ParsableTag::kParseUUID:
                case ParsableTag::kParseVec3:
                case ParsableTag::kParseVec4:
                {
                    ok = ConsumeToken(state, context, parseBit.tag, parsedSingle);
                    break;
                }
                case ParsableTag::kParseObject:
                {
                    // TODO: Although this should never result in a stack overflow, i'd rather return a request to prase than recursively call the same function
                    // Bah
                    ok = Parse(state, context, parseBit.objectParse, nestedresult);
                    // TODO: debug info
                    parsedSingle.object = nestedresult.result;
                    break;
                }
                default:
                    SysPanic("Invalid consume tag {} for {}", parseBit.tag, parseBit.label);
                }

                if (!ok)
                {
                    if ((parseBit.optional) || (parseBit.vararg))
                    {
                        break;
                    }

                    Aurora::Console::Logging::LogWarn("Syntax error around: label: {}, tag {}", parseBit.label, parseBit.tag);
                    return false;
                }

                if (parseBit.vararg || parseBit.array)
                {
                    parsed.count++;
                    parsed.value.array.push_back(parsedSingle);
                    parsed.isArray = true;
                }
                else
                {
                    parsed.isArray = false;
                    parsed.count = 1;
                    parsed.value.single = parsedSingle;
                }
            }

            // do not add if an optional bit was not serialized
            if (parsed.count != 0)
            {
                result.result.push_back(parsed);
            }
        }

        result.syntaxError = "No-Debug";
        result.debugTree = "No-Debug";
        return true;
    }

    AUKN_SYM bool Parse(ParseState &state, const ParseObject &structure, ParseResult &result)
    {
        ParseContext context(state.stringstream);
        return Parse(state, context, structure, result);
    }

    AUKN_SYM void SerializeToken(ParsableTag type, const ParseValue &value, AuString &str)
    {
        AuString temp = value.string;
        switch (type)
        {
        case ParsableTag::kParseUInt:
        {
            str += AuToString(value.primitive.uint);
            break;
        }
        case ParsableTag::kParseSInt:
        {
            str += AuToString(value.primitive.sint);
            break;
        }
        case ParsableTag::kParseNumber:
        {
            str += AuToString(value.primitive.number);
            break;
        }
        case ParsableTag::kParseVec3:
        {
            str += AuToString(value.primitive.vec3[0]) + " ";
            str += AuToString(value.primitive.vec3[1]) + " ";
            str += AuToString(value.primitive.vec3[2]);
            break;
        }
        case ParsableTag::kParseVec4:
        {
            str += AuToString(value.primitive.vec4[0]) + " ";
            str += AuToString(value.primitive.vec4[1]) + " ";
            str += AuToString(value.primitive.vec4[2]) + " ";
            str += AuToString(value.primitive.vec4[3]);
            break;
        }
        case ParsableTag::kParseString:
        {
            AuReplaceAll(temp, "\"", "\\\"");
            str += "\"" + temp + "\"";
            break;
        }
        case ParsableTag::kParseStringVararg:
        {
            AuReplaceAll(temp, "\n", "\\\n");
            str += temp;
            break;
        }
        case ParsableTag::kParseUUID:
        {
            str += uuids::to_string(value.UUID);
            break;
        }
        case ParsableTag::kParseBoolean:
        {
            if (value.primitive.boolean)
            {
                str += "true";
            }
            else
            {
                str += "false";
            }
            break;
        }
        default:
            SysPanic("Invalid consume tag {}", type);
        }
    }

    AUKN_SYM void Serialize(const ParsedObject &structure, AuString &ret)
    {
        for (auto &parsed : structure)
        {
            if (parsed.isArray)
            {
                ret += " ";
                ret += AuToString(parsed.count);
            }

            bool isArray = parsed.count > 1 || parsed.isArray;

            for (int i = 0; ((i < parsed.count)); i++)
            {
                ret += " ";

                ParseValueEx parsedSingle = {};
                ParseResult  nestedresult = {};
                switch (parsed.tag)
                {
                case ParsableTag::kParseUInt:
                case ParsableTag::kParseSInt:
                case ParsableTag::kParseString:
                case ParsableTag::kParseStringVararg:
                case ParsableTag::kParseNumber:
                case ParsableTag::kParseBoolean:
                case ParsableTag::kParseUUID:
                case ParsableTag::kParseVec3:
                case ParsableTag::kParseVec4:
                {
                    SerializeToken(parsed.tag, !isArray ? parsed.value.single : parsed.value.array[i], ret);
                    break;
                }
                case ParsableTag::kParseObject:
                {
                    Serialize(!isArray ? parsed.value.single.object : parsed.value.array[i].object, ret);
                    parsedSingle.object = nestedresult.result;
                    break;
                }
                default:
                    SysPanic("Invalid emit tag {}", parsed.tag);
                }
            }
        }

        ret = ret.substr(1);
    }
}