#include <string.h>
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "Buffer.h"
#include "generic.h"

Buffer::Buffer(bool _seekable) : Handle(-1), buffer(0), zero(0), realsiz(0), bufsiz(0), ptr(0), seekable(_seekable) { }

Buffer::~Buffer() {
    free(buffer);
}

Buffer::Buffer(const Buffer & b) : Handle(-1), buffer(0), zero(b.zero), realsiz(b.realsiz), bufsiz(b.bufsiz), ptr(b.ptr), seekable(b.seekable) {
    buffer = (Byte *) malloc(bufsiz);
    memcpy(buffer, b.buffer, bufsiz);
}

ssize_t Buffer::write(const void *buf, size_t count) throw (GeneralException) {
    if (!count) {
	return 0;
    }
    if (count + realsiz > bufsiz) {
	int numblocks = (count + realsiz) / realloc_threshold;
	int remains = (count + realsiz) % realloc_threshold;
	buffer = (Byte *) realloc(buffer, bufsiz = ((numblocks + (remains ? 1 : 0)) * realloc_threshold));
    }
    memcpy(buffer + realsiz, buf, count);
    realsiz += count;
    
    return count;
}

ssize_t Buffer::read(void *buf, size_t count) throw (GeneralException) {
    count = MIN(count, realsiz - ptr);

    if (!count) {
	return 0;
    }
    
    memcpy(buf, buffer + ptr, count);
    ptr += count;

    if (!seekable) {
        if (ptr >= realloc_threshold) {
	    int numblocks = (bufsiz / realloc_threshold) - (ptr / realloc_threshold);
	    memmove(buffer, buffer + (bufsiz - numblocks * realloc_threshold), numblocks * realloc_threshold);
	    ptr -= (bufsiz - numblocks * realloc_threshold);
	    realsiz -= (bufsiz - numblocks * realloc_threshold);
	    buffer = (Byte *) realloc(buffer, bufsiz = (numblocks * realloc_threshold));
        }
    }
    
    return count;
}

bool Buffer::CanRead() const {
    return true;
}

bool Buffer::CanWrite() const {
    return true;
}

String Buffer::GetName() const {
    return "Buffer";
}

Buffer Buffer::operator=(const Buffer & b) {
    if (b.buffer != buffer) {
	free(buffer);
	realsiz = b.realsiz;
	ptr = b.ptr;
        seekable = b.seekable;
	if ((bufsiz = b.bufsiz)) {
	    buffer = (Byte *) malloc(bufsiz);
	    memcpy(buffer, b.buffer, realsiz);
	} else {
	    buffer = 0;
	}
    }
    return *this;
}

bool Buffer::CanWatch() const {
    return false;
}

ssize_t Buffer::GetSize() const {
    return realsiz;
}

Byte Buffer::operator[](size_t p) const {
    if (p >= realsiz) {
	return 0;
    } else {
        if (seekable) {
            return buffer[p];
        } else {
            return buffer[ptr + p];
        }
    }
}

Byte & Buffer::operator[](size_t p) {
    if (p > bufsiz) {
	int numblocks = p / realloc_threshold;
	int remains = p % realloc_threshold;
	buffer = (Byte *) realloc(buffer, bufsiz = ((numblocks + (remains ? 1 : 0)) * realloc_threshold));
    }
    if (p >= realsiz) {
        memset(buffer + realsiz, 0, p - realsiz);
        realsiz = p;
    }

    if (seekable) {
        return buffer[p];
    } else {
        return buffer[ptr + p];
    }
}

bool Buffer::CanSeek() const {
    return seekable;
}

off_t Buffer::seek(off_t off, int wheel) throw (GeneralException) {
    if (!seekable) {
        throw GeneralException("This buffer is a fifo, thus is not seekable");
    }
    switch (wheel) {
    case SEEK_SET:
        ptr = off;
        break;
    case SEEK_CUR:
        ptr += off;
        break;
    case SEEK_END:
        ptr = realsiz + off;
        break;
    }
    operator[](ptr) = operator[](ptr);
    return ptr;
}

off_t Buffer::tell() const {
    return ptr;
}