/*
FLIF - Free Lossless Image Format

Copyright 2010-2016, Jon Sneyers & Pieter Wuille

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

#pragma once

#include <stdio.h>
#include <string.h>

class FileIO
{
private:
    FILE *file;
    const char *name;
	
	// prevent copy
	FileIO(const FileIO&) {}
	void operator=(const FileIO&) {}
	// prevent move, for now
	FileIO(FileIO&&) {}
	void operator=(FileIO&&) {}
public:
    const int EOS = EOF;

    FileIO(FILE* fil, const char *aname) : file(fil), name(aname) { }
    ~FileIO() {
        if (file) fclose(file);
    }
    void flush() {
        fflush(file);
    }
    bool isEOF() {
      return feof(file);
    }
    long ftell() {
      return ::ftell(file);
    }
    int getc() {
      return fgetc(file);
    }
    char * gets(char *buf, int n) {
      return fgets(buf, n, file);
    }
    int fputs(const char *s) {
      return ::fputs(s, file);
    }
    int fputc(int c) {
      return ::fputc(c, file);
    }
    void fseek(long offset, int where) {
      ::fseek(file, offset,where);
    }
    const char* getName() {
      return name;
    }
};

/*!
 * Read-only IO interface for a constant memory block
 */
class BlobReader
{
private:
    const uint8_t* data;
    size_t data_array_size;
    size_t seek_pos;
public:
    const int EOS = -1;

    BlobReader(const uint8_t* _data, size_t _data_array_size)
    : data(_data)
    , data_array_size(_data_array_size)
    , seek_pos(0)
    {
    }

    bool isEOF() const {
        return seek_pos >= data_array_size;
    }
    long ftell() const {
        return seek_pos;
    }
    int getc() {
        if(seek_pos >= data_array_size)
            return EOS;
        return data[seek_pos++];
    }
    char * gets(char *buf, int n) {
        int i = 0;
        const int max_write = n-1;
        while(seek_pos < data_array_size && i < max_write)
            buf[i++] = data[seek_pos++];
        buf[n-1] = '\0';

        if(i < max_write)
            return 0;
        else
            return buf;
    }
    int fputc(int c) {
      // cannot write on const memory
      return EOS;
    }
    void fseek(long offset, int where) {
        switch(where) {
        case SEEK_SET:
            seek_pos = offset;
            break;
        case SEEK_CUR:
            seek_pos += offset;
            break;
        case SEEK_END:
            seek_pos = long(data_array_size) + offset;
            break;
        }
    }
    static const char* getName() {
        return "BlobReader";
    }
};

/*!
 * IO interface for a growable memory block
 */
class BlobIO
{
private:
    uint8_t* data;
    // keeps track how large the array really is
    // HINT: should only be used in the grow() function
    size_t data_array_size;
    // keeps track how many bytes were written
    size_t bytes_used;
    size_t seek_pos;

    void grow(size_t necessary_size) {
        if(necessary_size < data_array_size)
            return;

        size_t new_size = necessary_size;
        // start with reasonably large array
        if(new_size < 4096)
            new_size = 4096;

        if(new_size < data_array_size * 3 / 2)
            new_size = data_array_size * 3 / 2;
        uint8_t* new_data = new uint8_t[new_size];

        memcpy(new_data, data, bytes_used);
        // if seek_pos has been moved beyond the written bytes,
        // fill the empty space with zeroes
        for(size_t i = bytes_used; i < seek_pos; ++i)
            new_data[i] = 0;
        delete [] data;
        data = new_data;
        std::swap(data_array_size, new_size);
    }
public:
    const int EOS = -1;

    BlobIO()
    : data(0)
    , data_array_size(0)
    , bytes_used(0)
    , seek_pos(0)
    {
    }

    ~BlobIO() {
        delete [] data;
    }

    uint8_t* release(size_t* array_size)
    {
        uint8_t* ptr = data;
        *array_size = bytes_used;

        data = 0;
        data_array_size = 0;
        bytes_used = 0;
        seek_pos = 0;
        return ptr;
    }

    static void flush() {
        // nothing to do
    }
    bool isEOF() const {
        return seek_pos >= bytes_used;
    }
    int ftell() const {
        return seek_pos;
    }
    int getc() {
        if(seek_pos >= bytes_used)
            return EOS;
        return data[seek_pos++];
    }
    char * gets(char *buf, int n) {
        int i = 0;
        const int max_write = n-1;
        while(seek_pos < bytes_used && i < max_write)
            buf[i++] = data[seek_pos++];
        buf[n-1] = '\0';

        if(i < max_write)
            return 0;
        else
            return buf;
    }
    int fputs(const char *s) {
        size_t i = 0;
        // null-terminated string
        while(s[i])
        {
            grow(seek_pos + 1);
            data[seek_pos++] = s[i++];
            if(bytes_used < seek_pos)
                bytes_used = seek_pos+1;
        }
        return 0;
    }
    int fputc(int c) {
        grow(seek_pos + 1);

        data[seek_pos++] = static_cast<uint8_t>(c);
        if(bytes_used < seek_pos)
            bytes_used = seek_pos+1;
        return c;
    }
    void fseek(long offset, int where) {
        switch(where) {
        case SEEK_SET:
            seek_pos = offset;
            break;
        case SEEK_CUR:
            seek_pos += offset;
            break;
        case SEEK_END:
            seek_pos = long(bytes_used) + offset;
            break;
        }
    }
    static const char* getName() {
        return "BlobIO";
    }
};