#ifndef CORE_ARRAY_STRING_HPP
#define CORE_ARRAY_STRING_HPP

#include "math/Math.hpp"
#include "utils/Check.hpp"
#include "utils/Types.hpp"
#include "utils/Utility.hpp"

namespace Core {
    template<typename T>
    constexpr int stringLength(const T* c) {
        int i = 0;
        while(*c != '\0') {
            c++;
            i++;
        }
        return i;
    }

    template<int N, typename CharType>
    class ArrayString final {
        int length;
        u32 hash;
        static_assert(N > 0, "size of array string must be positive");
        CharType data[static_cast<unsigned int>(N)];

    public:
        ArrayString() : length(0), hash(0) {
            data[0] = '\0';
        }

        bool operator==(const CharType* s) const {
            for(int i = 0; i < length; i++, s++) {
                if(*s == '\0' && *s != data[i]) {
                    return false;
                }
            }
            return *s == '\0';
        }

        template<int L>
        bool operator==(const ArrayString<L, CharType>& other) const {
            if(length != other.getLength()) {
                return false;
            }
            for(int i = 0; i < length; i++) {
                if(data[i] != other[i]) {
                    return false;
                }
            }
            return true;
        }

        bool operator!=(const CharType* s) const {
            return !((*this) == s);
        }

        template<int L>
        bool operator!=(const ArrayString<L, CharType>& other) const {
            return !((*this) == other);
        }

        CharType operator[](int index) const {
            return data[index];
        }

        int getLength() const {
            return length;
        }

        constexpr int getCapacity() const {
            return N - 1;
        }

        check_return Error append(char c) {
            return add(static_cast<CharType>(c));
        }

        check_return Error append(signed char c) {
            return append(static_cast<char>(c));
        }

        check_return Error append(unsigned char c) {
            return append(static_cast<char>(c));
        }

        check_return Error append(wchar_t c) {
            return append(static_cast<c32>(c));
        }

        check_return Error append(c32 c) {
            if constexpr(IsSame<CharType, char>) {
                char buffer[5];
                unicodeToChar(c, buffer);
                return append(static_cast<const char*>(buffer));
            } else {
                return add(c);
            }
        }

        check_return Error append(const char* s) {
            if constexpr(IsSame<CharType, char>) {
                // stringLength as s could be some part of data
                for(int i = stringLength(s); i > 0; i--) {
                    CORE_RETURN_ERROR(append(*(s++)));
                }
                return Error::NONE;
            } else {
                while(true) {
                    c32 u = 0;
                    CORE_RETURN_ERROR(readUnicode(u, s));
                    if(u == 0) {
                        return Error::NONE;
                    }
                    CORE_RETURN_ERROR(append(u));
                }
            }
        }

        check_return Error append(const c32* s) {
            // stringLength as s could be some part of data
            for(int i = stringLength(s); i > 0; i--) {
                CORE_RETURN_ERROR(append(*(s++)));
            }
            return Error::NONE;
        }

        check_return Error append(const signed char* s) {
            return append(reinterpret_cast<const char*>(s));
        }

        check_return Error append(const unsigned char* s) {
            return append(reinterpret_cast<const char*>(s));
        }

        check_return Error append(signed short s) {
            return convertAppend(s);
        }

        check_return Error append(unsigned short s) {
            return convertAppend(s);
        }

        check_return Error append(signed int i) {
            return convertAppend(i);
        }

        check_return Error append(unsigned int i) {
            return convertAppend(i);
        }

        check_return Error append(signed long l) {
            return convertAppend(l);
        }

        check_return Error append(unsigned long l) {
            return convertAppend(l);
        }

        check_return Error append(signed long long ll) {
            return convertAppend(ll);
        }

        check_return Error append(unsigned long long ll) {
            return convertAppend(ll);
        }

        check_return Error append(float f) {
            return convertAppend(static_cast<double>(f));
        }

        check_return Error append(double d) {
            return convertAppend(d);
        }

        check_return Error append(long double ld) {
            return convertAppend(ld);
        }

        check_return Error append(bool b) {
            return b ? append("true") : append("false");
        }

        check_return Error append(Error e) {
            return append(getErrorName(e));
        }

        template<typename T>
        check_return Error append(const T& t) {
            return t.toString(*this);
        }

        template<int L, typename C>
        check_return Error toString(ArrayString<L, C>& s) const {
            if constexpr(IsSame<CharType, char> && !IsSame<C, char>) {
                // utf32 to utf8
                return s.append(data);
            }
            int l = length; // length changes if &s == this
            for(int i = 0; i < l; i++) {
                CORE_RETURN_ERROR(s.append(data[i]));
            }
            return Error::NONE;
        }

        void clear() {
            length = 0;
            hash = 0;
            data[0] = '\0';
        }

        u32 hashCode() const {
            return hash;
        }

        check_return Error print() const {
            if constexpr(IsSame<CharType, char>) {
                for(int i = 0; i < length; i++) {
                    CORE_RETURN_ERROR(Core::putChar(data[i]));
                }
                return Error::NONE;
            } else {
                for(int i = 0; i < length; i++) {
                    c32 c = data[i];
                    if(c < (1 << 7)) {
                        CORE_RETURN_ERROR(printChar(c, 0, 0x7F, 0x0));
                    } else if(c < (1 << 11)) {
                        CORE_RETURN_ERROR(printChar(c, 6, 0x1F, 0xC0));
                        CORE_RETURN_ERROR(printChar(c, 0, 0x3F, 0x80));
                    } else if(c < (1 << 16)) {
                        CORE_RETURN_ERROR(printChar(c, 12, 0x0F, 0xE0));
                        CORE_RETURN_ERROR(printChar(c, 6, 0x3F, 0x80));
                        CORE_RETURN_ERROR(printChar(c, 0, 0x3F, 0x80));
                    } else if(c < (1 << 21)) {
                        CORE_RETURN_ERROR(printChar(c, 18, 0x07, 0xF0));
                        CORE_RETURN_ERROR(printChar(c, 12, 0x3F, 0x80));
                        CORE_RETURN_ERROR(printChar(c, 6, 0x3F, 0x80));
                        CORE_RETURN_ERROR(printChar(c, 0, 0x3F, 0x80));
                    }
                }
                return Error::NONE;
            }
        }

        check_return Error printLine() const {
            CORE_RETURN_ERROR(print());
            CORE_RETURN_ERROR(Core::putChar('\n'));
            return Error::NONE;
        }

        template<typename... Args>
        check_return Error format(Args&&... args) {
            ArrayString s;
            Error e = formatBuffer(s, 0, Core::forward<Args>(args)...);
            if(e == Error::NONE || e == Error::CAPACITY_REACHED) {
                *this = s;
            }
            return e;
        }

        template<int L>
        bool startsWidth(const ArrayString<L, CharType>& other,
                         int from = 0) const {
            if(from + other.getLength() > length) {
                return false;
            }
            for(int i = 0; i < other.getLength(); i++) {
                if(data[from + i] != other[i]) {
                    return false;
                }
            }
            return true;
        }

        template<int L>
        int search(const ArrayString<L, CharType>& other, int from = 0) const {
            for(int i = from; i < length; i++) {
                if(startsWidth(other, i)) {
                    return i;
                }
            }
            return -1;
        }

        template<int L>
        bool contains(const ArrayString<L, CharType>& other,
                      int from = 0) const {
            return search(other, from) >= 0;
        }

        int search(CharType u, int from = 0) const {
            for(int i = from; i < length; i++) {
                if(data[i] == u) {
                    return i;
                }
            }
            return -1;
        }

        bool contains(CharType u, int from = 0) const {
            return search(u, from) >= 0;
        }

        ArrayString substring(int from, int to) const {
            from = Math::max(from, 0);
            to = Math::min(to, length - 1);
            ArrayString s;
            for(int i = from; i <= to; i++) {
                (void)s.append(data[i]);
            }
            return s;
        }

        ArrayString substring(int from = 0) const {
            return substring(from, length - 1);
        }

        template<int L1, int L2>
        check_return Error replace(const ArrayString<L1, CharType>& search,
                                   const ArrayString<L2, CharType>& replace) {
            ArrayString<N, CharType> s;
            int i = 0;
            while(i < length) {
                if(startsWidth(search, i)) {
                    CORE_RETURN_ERROR(s.append(replace));
                    i += search.getLength();
                } else {
                    CORE_RETURN_ERROR(s.append(data[i]));
                    i++;
                }
            }
            *this = s;
            return Error::NONE;
        }

        void replace(CharType search, CharType replace) {
            hash = 0;
            for(int i = 0; i < length; i++) {
                if(data[i] == search) {
                    data[i] = replace;
                }
                addToHash(static_cast<c32>(data[i]));
            }
        }

        operator const CharType*() const {
            return data;
        }

    private:
        Error add(CharType c) {
            if(length >= N - 1) {
                return Error::CAPACITY_REACHED;
            }
            data[length++] = c;
            data[length] = '\0';
            addToHash(static_cast<c32>(c));
            return Error::NONE;
        }

        template<unsigned int L>
        void unicodeToChar(c32 c, char (&buffer)[L]) {
            static_assert(L >= 5, "to small char buffer");
            if(c < (1 << 7)) {
                buffer[0] = static_cast<char>(((c >> 0) & 0x7F) | 0x0);
                buffer[1] = '\0';
            } else if(c < (1 << 11)) {
                buffer[0] = static_cast<char>(((c >> 6) & 0x1F) | 0xC0);
                buffer[1] = static_cast<char>(((c >> 0) & 0x3F) | 0x80);
                buffer[2] = '\0';
            } else if(c < (1 << 16)) {
                buffer[0] = static_cast<char>(((c >> 12) & 0x0F) | 0xE0);
                buffer[1] = static_cast<char>(((c >> 6) & 0x3F) | 0x80);
                buffer[2] = static_cast<char>(((c >> 0) & 0x3F) | 0x80);
                buffer[3] = '\0';
            } else if(c < (1 << 21)) {
                buffer[0] = static_cast<char>(((c >> 18) & 0x07) | 0xF0);
                buffer[1] = static_cast<char>(((c >> 12) & 0x3F) | 0x80);
                buffer[2] = static_cast<char>(((c >> 6) & 0x3F) | 0x80);
                buffer[3] = static_cast<char>(((c >> 0) & 0x3F) | 0x80);
                buffer[4] = '\0';
            } else {
                buffer[0] = '\0';
            }
        }

        check_return static Error printChar(c32 u, u32 shift, u32 a, u32 o) {
            return Core::putChar(static_cast<int>(((u >> shift) & a) | o));
        }

        static c32 read(const char*& s) {
            if(*s == '\0') {
                return 0;
            }
            return static_cast<c32>(*(s++));
        }

        static Error readUnicode(c32& u, const char*& s) {
            u = read(s);
            if((u & 0x80) == 0) {
                return Error::NONE;
            }
            if((u & 0xE0) == 0xC0) {
                c32 u2 = read(s);
                if(u2 == 0) {
                    return Error::INVALID_CHAR;
                }
                u = ((u & 0x1F) << 6) | (u2 & 0x3F);
                return Error::NONE;
            } else if((u & 0xF0) == 0xE0) {
                c32 u2 = read(s);
                c32 u3 = read(s);
                if(u2 == 0 || u3 == 0) {
                    return Error::INVALID_CHAR;
                }
                u = ((u & 0xF) << 12) | ((u2 & 0x3F) << 6) | (u3 & 0x3F);
                return Error::NONE;
            } else if((u & 0xF8) == 0xF0) {
                c32 u2 = read(s);
                c32 u3 = read(s);
                c32 u4 = read(s);
                if(u2 == 0 || u3 == 0 || u4 == 0) {
                    return Error::INVALID_CHAR;
                }
                u = ((u & 0x07) << 18) | ((u2 & 0x3F) << 12) |
                    ((u3 & 0x3F) << 6) | (u4 & 0x3F);
                return Error::NONE;
            }
            return Error::INVALID_CHAR;
        }

        void addToHash(c32 u) {
            hash = static_cast<u32>(2120251889) * hash + static_cast<u32>(u);
        }

        template<typename T, typename... Args>
        check_return Error formatBuffer(ArrayString& s, int index, const T& t,
                                        Args&&... args) {
            while(index < length) {
                CharType u = data[index++];
                if(u == '#') {
                    if(index >= length ||
                       (index < length && data[index] != '#')) {
                        break;
                    }
                    index++;
                }
                CORE_RETURN_ERROR(s.append(u));
            }
            CORE_RETURN_ERROR(s.append(t));
            return formatBuffer(s, index, Core::forward<Args>(args)...);
        }

        check_return Error formatBuffer(ArrayString& s, int index) {
            while(index < length) {
                CORE_RETURN_ERROR(s.append(data[index++]));
            }
            return Error::NONE;
        }

        template<typename T>
        check_return Error convertAppend(T t) {
            char buffer[64];
            CORE_RETURN_ERROR(Core::toString(t, buffer, CORE_SIZE(buffer)));
            return append(static_cast<const char*>(buffer));
        }
    };

    template<typename String, typename Iterable>
    check_return Error toString(String& s, const Iterable& i) {
        CORE_RETURN_ERROR(s.append("["));
        auto current = i.begin();
        auto end = i.end();
        while(current != end) {
            CORE_RETURN_ERROR(s.append(*current));
            ++current;
            if(current != end) {
                CORE_RETURN_ERROR(s.append(", "));
            }
        }
        return s.append("]");
    }

    template<int N>
    using String8 = ArrayString<N, char>;

    template<int N>
    using String32 = ArrayString<N, char32_t>;
}

template<int N, typename CharType>
bool operator==(const CharType* cs, const Core::ArrayString<N, CharType>& s) {
    return s == cs;
}

template<int N, typename CharType>
bool operator!=(const CharType* cs, const Core::ArrayString<N, CharType>& s) {
    return s != cs;
}

#endif