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

    File: AuParser.cpp
    Date: 2021-6-12
    Author: Reece
    Note: Horrible gen 1 parser.
          I'm not removing or significantly improving this.
          Just build around what works, could probably wrangle a command list parser on top.
***/
#include <Source/RuntimeInternal.hpp>
#include "AuParser.hpp"

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

    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, 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 escapeNextLegal = false;

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

        while (true)
        {
            AuUInt8 cur;
            AuUInt8 peek;

            // consume character from the stream 
            if (!state.stream->Next(cur))
            {
                break;
            }

            // some characters should be considered universally illegal such as nasty unicode spaces,
            // carriage returns, and any other nasty crash exploit dependee characters
            if (isIgnore(cur))
            {
                continue;
            }

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

            // if the string starts with a quotation mark, set stringLevel to true
            // TODO: I dont remember the parse rules. Check the old tests. Should this be AuStartsWith?
            if ((cur == '"') && (isString) && (out.empty()))
            {
                stringLevel = true;
                continue;
            }
            
            auto peekStatus = state.stream->PeekNext(peek);

            bool isPeekterminating = isTerminating(peek);

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

                // escape character for "'s in strings 
                if (isString && (peek == '\"' || peek == ' ' || peek == '\n' || peek == '\r'))
                {
                    escapeNextLegal = true;
                    continue;
                }
            }

            // see above
            if (AuExchange(escapeNextLegal, false))
            {
                out += cur;
                continue;
            }

            // match the ending '"' character in the token to terminate strings containing spaces
            // do not make this more ambiguous by removing the  **else if**.
            if (
                (cur == '"') && (isString) && (stringLevel)  // 
                                                             // can we expect to fail next iteration?
                && (((peekStatus && (isPeekterminating || isSpace(peek)) /*Is ending character?*/) ||
                    (!peekStatus))))  // Is EoS?
            {
                stringLevel = false;
                continue;
            }
           
            // 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(cur)) && (!stringLevel) && (!isvararg))
            {
                break;
            }

            // otherwise emit
            out += cur;
        }

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

        //AuLogDbg("returned {} {}", out, out.size() != 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, typename Iterator>
    bool ParseInt(Iterator begin, Iterator &end, T &out)
    {
        T res = 0;
        T sign = 1;
        out = 0;

        auto itr = begin;

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

        int perf {};
        for (;
             (itr != 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 ((perf++) >= 5)
            {
                if constexpr (AuIsSame_v<T, AuUInt>)
                {
                    if (old > res)
                    {
                        SysPushErrorSyntaxError("Unsigned integer overflow: {}", AuString(begin, end));
                        end = itr;
                        return false;
                    }
                }
                else if constexpr (AuIsSame_v<T, AuSInt>)
                {
                    if (SignBit(old) != SignBit(res))
                    {
                        SysPushErrorSyntaxError("Signed integer overflow: {}", AuString(begin, end));
                        end = itr;
                        return false;
                    }
                }
            }
        }

        end = itr;
        out = res * sign;
        return true;
    }

    template <typename T, typename Iterator>
    bool ParseInt16(Iterator begin, Iterator &end, T &out)
    {
        T res = 0;
        T sign = 1;
        out = 0;

        auto itr = begin;

        if (begin == end)
        {
            return false;
        }

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

        if (itr != end)
        {
            if ((*itr == '0') && (itr[1] == 'x')) // TODO (Reece): EVIL... but it's only a byte
            {
                itr++;
                itr++;
            }
        }

        if (begin != end)
        {
            auto endChar = *(end - 1);
            if (endChar == 'h' || endChar == 'H')
            {
                end--;
            }
        }

        int perf {};
        for (;
             (itr != end) &&
             (*itr != '\0');
             itr++)
        {
            auto c = *itr;

            int delta {};
            if ((c >= 'A') && (c <= 'F'))
            {
                delta = 10 + (c - 'A');
            }
            else if ((c >= 'a') && (c <= 'f'))
            {
                delta = 10 + (c - 'a');
            }
            else if ((c >= '0') && (c <= '9'))
            {
                delta = c - '0';
            }
            else
            {
                return false;
            }

            auto old = res;

            res *= T(16);
            res += T(delta);

            if ((perf++) >= 5)
            {
                if constexpr (AuIsSame_v<T, AuUInt>)
                {
                    if (old > res)
                    {
                        SysPushErrorSyntaxError("Unsigned integer overflow: {}", AuString(begin, end));
                        end = itr;
                        return false;
                    }
                }
                else if constexpr (AuIsSame_v<T, AuSInt>)
                {
                    if (SignBit(old) != SignBit(res))
                    {
                        SysPushErrorSyntaxError("Signed integer overflow: {}", AuString(begin, end));
                        end = itr;
                        return false;
                    }
                }
            }
        }

        end = itr;
        out = res * sign;
        return true;
    }

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

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

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

        AuOptional<uuids::uuid> uuid;
        auto end = str.end();
        switch (type)
        {
        case ParsableTag::kParseUInt:
        {
            return ParseInt<AuUInt64>(str.begin(), end, out.primitive.uint) && end == str.end();
        }
        case ParsableTag::kParseSInt:
        {
            return ParseInt<AuInt64>(str.begin(), end, out.primitive.sint) && end == str.end();
        }
        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 = AuMove(str);
            break;
        }
        case ParsableTag::kParseUUID:
        {
            if (auto uuid2 = uuids::uuid::from_string(str))
            {
                uuid = *uuid2;
            }
            if (!uuid.has_value())
            {
                SysPushErrorSyntaxError("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
            {
                SysPushErrorSyntaxError("Parsed tag of boolean type wasn't parsable given the English string {}", str);
                return false;
            }
            break;
        }
        default:
            SysPanic("Invalid consume tag {}", AuUInt(type));
        }

        return true;
    }

    AUKN_SYM bool ConsumeToken(ParseState &state, ParsableTag type, ParseValue &out)
    {
        ParseValue temp;

    #define ADD_VECTOR_VAL(idx, memberType)                                      \
            if (!ConsumeTokenPrimitiveish(state, 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, type, out);
        }
        }

    #undef ADD_VECTOR_VAL
    }

    AUKN_SYM bool ConsumeToken(ParsableTag type, const AuSPtr<Aurora::IO::Character::ICharacterProvider> &getc, ParseValue &out)
    {
        ParseState state(getc);
        return ConsumeToken(state, type, out);
    }

    AUKN_SYM bool ConsumeToken(ParsableTag type, const AuSPtr<Aurora::IO::Character::IBufferedCharacterConsumer> &getc, ParseValue &out)
    {
        ParseState state(getc);
        return ConsumeToken(state, type, out);
    }

    AUKN_SYM AuList<AuParse::ParseValueEx> ConsumeTokens(ParsableTag type, const AuSPtr<Aurora::IO::Character::IBufferedCharacterConsumer> &getc)
    {
        AuList<AuParse::ParseValueEx> ret;
        AuParse::ParseValueEx res;
        AuParse::ParseState state(getc);

        while (AuParse::ConsumeToken(state, type, res))
        {
            ret.push_back(res);
        }

        return ret;
    }

    AUKN_SYM AuList<AuParse::ParseValueEx> ConsumeTokens(ParsableTag type, const AuSPtr<Aurora::IO::Character::ICharacterProvider> &getc)
    {
        AuList<AuParse::ParseValueEx> ret;
        AuParse::ParseValueEx res;
        AuParse::ParseState state(getc);

        while (AuParse::ConsumeToken(state, type, res))
        {
            ret.push_back(res);
        }

        return ret;
    }

    AUKN_SYM bool Parse(ParseState &state, 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, ParsableTag::kParseUInt, arrayLengthBit))
                {
                    SysPushErrorSyntaxError("Couldn't consume array length, label: {}, tag {}", parseBit.label, (AuUInt)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, 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, parseBit.objectParse, nestedresult);
                    // TODO: debug info
                    parsedSingle.object = nestedresult.result;
                    break;
                }
                default:
                    SysPanic("Invalid consume tag {} for {}", (AuUInt)parseBit.tag, parseBit.label);
                }

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

                    SysPushErrorSyntaxError("Syntax error around: label: {}, tag {}", parseBit.label, (AuUInt)parseBit.tag);
                    return false;
                }

                if (parseBit.vararg || parseBit.array)
                {
                    parsed.count++;
                    if (!AuTryInsert(parsed.value.array, parsedSingle))
                    {
                        SysPushErrorMem();
                        return false;
                    }
                    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 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, "\\", "\\\\");
            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 {}", (AuUInt)type);
        }
    }

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

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

            for (int i = 0; ((i < parsed.count)); i++)
            {
                if (ret.size())
                {
                    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 {}", (AuUInt)parsed.tag);
                }
            }
        }
    }

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

        if (!ParseInt<AuUInt>(begin, end, temp))
        {
            return {};
        }

        return temp;
    }

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

        if (!ParseInt<AuSInt>(begin, end, temp))
        {
            return {};
        }

        return temp;
    }

    AUKN_SYM AuResult<AuUInt> ParseUInt16(const char *begin, const char *&end)
    {
        AuUInt temp{};

        if (!ParseInt16<AuUInt>(begin, end, temp))
        {
            return {};
        }

        return temp;
    }

    AUKN_SYM AuResult<AuSInt> ParseSInt16(const char *begin, const char *&end)
    {
        AuSInt temp{};

        if (!ParseInt16<AuSInt>(begin, end, temp))
        {
            return {};
        }

        return temp;
    }

    AUKN_SYM AuString StringifySInt16(AuInt64 in, bool bZeroX)
    {
        if (bZeroX)
        {
            auto str = AuString(fmt::format("{0:#X}", in));
            if (str.size() > 2)
            {
                if (str[1] == 'X')
                {
                    str[1] = 'x';
                }
                else if (str.size() > 3 && str[2] == 'X')
                {
                    str[2] = 'x';
                }
            }
            return str;
        }
        else
        {
            return AuString(fmt::format("{:X}", in));
        }
    }

    AUKN_SYM AuString StringifyUInt16(AuUInt64 in, bool bZeroX)
    {
        if (bZeroX)
        {
            auto str = AuString(fmt::format("{0:#X}", in));
            if (str.size() > 2)
            {
                if (str[1] == 'X')
                {
                    str[1] = 'x';
                }
                else if (str.size() > 3 && str[2] == 'X')
                {
                    str[2] = 'x';
                }
            }
            return str;
        }
        else
        {
            return AuString(fmt::format("{:X}", in));
        }
    }

    AUKN_SYM AuResult<AuSInt> ParseSInt16(const char *begin)
    {
        const auto end = begin + ::strlen(begin);
        const char *didntFuckingAskTYVM {end };

        auto res = ParseSInt16(begin, didntFuckingAskTYVM);
        if (!res.has_value())
        {
            return {};
        }

        if (didntFuckingAskTYVM != end)
        {
            return {};
        }

        return res;
    }

    AUKN_SYM AuResult<AuSInt> ParseSInt16(const AuROString &str)
    {
        const char *didntFuckingAskTYVM { &str[str.size()] };

        auto res = ParseSInt16(str.data(), didntFuckingAskTYVM);
        if (!res.has_value())
        {
            return {};
        }

        if (didntFuckingAskTYVM != &str[str.size()])
        {
            return {};
        }

        return res;
    }

    AUKN_SYM AuResult<AuUInt> ParseUInt16(const char *begin)
    {
        const auto end = begin + ::strlen(begin);
        const char *didntFuckingAskTYVM { end };

        auto res = ParseUInt16(begin, didntFuckingAskTYVM);
        if (!res.has_value())
        {
            return {};
        }

        if (didntFuckingAskTYVM != end)
        {
            return {};
        }

        return res;
    }

    AUKN_SYM AuResult<AuUInt> ParseUInt16(const AuROString &str)
    {
        const char *didntFuckingAskTYVM { &str[str.size()] };

        auto res = ParseUInt16(str.data(), didntFuckingAskTYVM);
        if (!res.has_value())
        {
            return {};
        }

        if (didntFuckingAskTYVM != &str[str.size()])
        {
            return {};
        }

        return res;
    }

    AUKN_SYM AuResult<AuSInt> ParseSInt(const AuROString &str)
    {
        const char *didntFuckingAskTYVM { &str[str.size()] };

        auto res = ParseSInt(str.data(), didntFuckingAskTYVM);
        if (!res.has_value())
        {
            return {};
        }

        if (didntFuckingAskTYVM != &str[str.size()])
        {
            return {};
        }

        return res;
    }

    AUKN_SYM AuResult<AuSInt> ParseSInt(const char *begin)
    {
        const auto end = begin + ::strlen(begin);
        const char *didntFuckingAskTYVM { end };

        auto res = ParseSInt(begin, didntFuckingAskTYVM);
        if (!res.has_value())
        {
            return {};
        }

        if (didntFuckingAskTYVM != end)
        {
            return {};
        }

        return res;
    }

    AUKN_SYM AuResult<AuUInt> ParseUInt(const AuROString &str)
    {
        const char *didntFuckingAskTYVM { &str[str.size()] };

        auto res = ParseUInt(str.data(), didntFuckingAskTYVM);
        if (!res.has_value())
        {
            return {};
        }

        if (didntFuckingAskTYVM != &str[str.size()])
        {
            return {};
        }

        return res;
    }

    AUKN_SYM AuResult<AuUInt> ParseUInt(const char *begin)
    {
        const auto end = begin + ::strlen(begin);
        const char *didntFuckingAskTYVM { end };

        auto res = ParseUInt(begin, didntFuckingAskTYVM);
        if (!res.has_value())
        {
            return {};
        }

        if (didntFuckingAskTYVM != end)
        {
            return {};
        }

        return res;
    }
}