#ifndef CORE_STRING_H
#define CORE_STRING_H

#include <stdarg.h>
#include <stdio.h>

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

namespace Core {
    template<int N>
    class ArrayString final {
    public:
        int length;
        u32 hash;
        static constexpr int DATA_LENGTH =
            (N - Math::max(CORE_SIZE(length), CORE_SIZE(hash))) /
            CORE_SIZE(u32);
        static_assert(DATA_LENGTH > 0, "Size of array string too small");
        u32 data[static_cast<unsigned int>(DATA_LENGTH)];

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

        bool operator==(const char* s) const {
            for(int i = 0; i < length; i++) {
                u32 u = 0;
                if(readUnicode(u, s) || data[i] != u) {
                    return false;
                }
            }
            return read(s) == 0;
        }

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

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

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

        u32 operator[](int index) const {
            return data[index];
        }

        int getLength() const {
            return length;
        }

        constexpr int getCapacity() const {
            return DATA_LENGTH;
        }

        // returns true on error
        check_return bool append(char c) {
            if(c < 0) {
                return true;
            }
            return appendUnicode(static_cast<u32>(c));
        }

        // returns true on error
        check_return bool append(signed char c) {
            if(c < 0) {
                return true;
            }
            return appendUnicode(static_cast<u32>(c));
        }

        // returns true on error
        check_return bool append(unsigned char c) {
            return appendUnicode(c);
        }

        // returns true on error
        check_return bool append(const char* s) {
            while(true) {
                u32 u = 0;
                if(readUnicode(u, s)) {
                    return true;
                } else if(u == 0) {
                    return false;
                } else if(appendUnicode(u)) {
                    return true;
                }
            }
            return false;
        }

        // returns true on error
        check_return bool append(const signed char* s) {
            return append(reinterpret_cast<const char*>(s));
        }

        // returns true on error
        check_return bool append(const unsigned char* s) {
            return append(reinterpret_cast<const char*>(s));
        }

        // returns true on error
        check_return bool append(signed short s) {
            return appendFormat("%hd", s);
        }

        // returns true on error
        check_return bool append(unsigned short s) {
            return appendFormat("%hu", s);
        }

        // returns true on error
        check_return bool append(signed int i) {
            return appendFormat("%d", i);
        }

        // returns true on error
        check_return bool append(unsigned int i) {
            return appendFormat("%u", i);
        }

        // returns true on error
        check_return bool append(signed long l) {
            return appendFormat("%ld", l);
        }

        // returns true on error
        check_return bool append(unsigned long l) {
            return appendFormat("%lu", l);
        }

        // returns true on error
        check_return bool append(signed long long ll) {
            return appendFormat("%lld", ll);
        }

        // returns true on error
        check_return bool append(unsigned long long ll) {
            return appendFormat("%llu", ll);
        }

        // returns true on error
        check_return bool append(float f) {
            return appendFormat("%.2f", static_cast<double>(f));
        }

        // returns true on error
        check_return bool append(double d) {
            return appendFormat("%.2f", d);
        }

        // returns true on error
        check_return bool append(long double ld) {
            return appendFormat("%.2Lf", ld);
        }

        // returns true on error
        check_return bool append(bool b) {
            return b ? append("true") : append("false");
        }

        // returns true on error
        check_return bool appendUnicode(u32 c) {
            if(length >= DATA_LENGTH) {
                return true;
            }
            data[length++] = c;
            addToHash(c);
            return false;
        }

        // returns true on error
        template<typename T>
        check_return bool append(const T& t) {
            return t.toString(*this);
        }

        // returns true on error
        template<int L>
        check_return bool toString(ArrayString<L>& s) const {
            int l = length; // length changes if &s == this
            for(int i = 0; i < l; i++) {
                if(s.appendUnicode(data[i])) {
                    return true;
                }
            }
            return false;
        }

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

        u32 hashCode() const {
            return hash;
        }

        // returns true on error
        check_return bool print() const {
            for(int i = 0; i < length; i++) {
                u32 c = data[i];
                if(c < (1 << 7)) {
                    if(putchar(static_cast<int>(c & 0x7F)) == EOF) {
                        return true;
                    }
                } else if(c < (1 << 11)) {
                    if(printChar(c, 6, 0x1F, 0xC0) ||
                       printChar(c, 0, 0x3F, 0x80)) {
                        return true;
                    }
                } else if(c < (1 << 16)) {
                    if(printChar(c, 12, 0x0F, 0xE0) ||
                       printChar(c, 6, 0x3F, 0x80) ||
                       printChar(c, 0, 0x3F, 0x80)) {
                        return true;
                    }
                } else if(c < (1 << 21)) {
                    if(printChar(c, 18, 0x07, 0xF0) ||
                       printChar(c, 12, 0x3F, 0x80) ||
                       printChar(c, 6, 0x3F, 0x80) ||
                       printChar(c, 0, 0x3F, 0x80)) {
                        return true;
                    }
                }
            }
            return false;
        }

        // returns true on error
        check_return bool printLine() const {
            return print() || putchar('\n') == EOF;
        }

        // returns true on error
        template<typename... Args>
        check_return bool format(Args&&... args) {
            ArrayString s;
            if(formatBuffer(s, 0, Core::forward<Args>(args)...)) {
                return true;
            }
            *this = s;
            return false;
        }

    private:
        static bool printChar(u32 u, u32 shift, u32 a, u32 o) {
            return putchar(static_cast<int>(((u >> shift) & a) | o)) == EOF;
        }
        static u32 read(const char*& s) {
            if(*s == '\0') {
                return 0;
            }
            return static_cast<u32>(*(s++));
        }

        // returns true on error
        static bool readUnicode(u32& u, const char*& s) {
            u = read(s);
            if((u & 0x80) == 0) {
                return false;
            }
            if((u & 0xE0) == 0xC0) {
                u32 u2 = read(s);
                if(u2 == 0) {
                    return true;
                }
                u = ((u & 0x1F) << 6) | (u2 & 0x3F);
                return false;
            } else if((u & 0xF0) == 0xE0) {
                u32 u2 = read(s);
                u32 u3 = read(s);
                if(u2 == 0 || u3 == 0) {
                    return true;
                }
                u = ((u & 0xF) << 12) | ((u2 & 0x3F) << 6) | (u3 & 0x3F);
                return false;
            } else if((u & 0xF8) == 0xF0) {
                u32 u2 = read(s);
                u32 u3 = read(s);
                u32 u4 = read(s);
                if(u2 == 0 || u3 == 0 || u4 == 0) {
                    return true;
                }
                u = ((u & 0x07) << 18) | ((u2 & 0x3F) << 12) |
                    ((u3 & 0x3F) << 6) | (u4 & 0x3F);
                return false;
            }
            return true;
        }

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

        // returns true on error
        template<typename T, typename... Args>
        check_return bool formatBuffer(ArrayString& s, int index, const T& t,
                                       Args&&... args) {
            while(index < length) {
                u32 u = data[index++];
                if(u == '#') {
                    if(index >= length ||
                       (index < length && data[index] != '#')) {
                        break;
                    }
                    index++;
                }
                if(s.appendUnicode(u)) {
                    return true;
                }
            }
            if(s.append(t)) {
                return true;
            }
            return formatBuffer(s, index, Core::forward<Args>(args)...);
        }

        // returns true on error
        check_return bool formatBuffer(ArrayString& s, int index) {
            while(index < length) {
                if(s.appendUnicode(data[index++])) {
                    return true;
                }
            }
            return false;
        }

        // returns true on error
        check_format(2, 3) check_return
            bool appendFormat(const char* format, ...) {
            constexpr int BUFFER_SIZE = 64;
            char buffer[BUFFER_SIZE];

            va_list args;
            va_start(args, format);
            int written = vsnprintf(buffer, BUFFER_SIZE, format, args);
            va_end(args);

            return written >= BUFFER_SIZE ||
                   append(static_cast<const char*>(buffer));
        }
    };
}

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

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

#endif