/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2017 Mike Becker, Olaf Wintermann All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "ucx/buffer.h"

#include <stdarg.h>
#include <stdlib.h>
#include <string.h>

UcxBuffer *ucx_buffer_new(void *space, size_t capacity, int flags) {
    UcxBuffer *buffer = (UcxBuffer*) malloc(sizeof(UcxBuffer));
    if (buffer) {
        buffer->flags = flags;
        if (!space) {
            buffer->space = (char*)malloc(capacity);
            if (!buffer->space) {
                free(buffer);
                return NULL;
            }
            memset(buffer->space, 0, capacity);
            buffer->flags |= UCX_BUFFER_AUTOFREE;
        } else {
            buffer->space = (char*)space;
        }
        buffer->capacity = capacity;
        buffer->size = 0;

        buffer->pos = 0;
    }

    return buffer;
}

void ucx_buffer_free(UcxBuffer *buffer) {
    if ((buffer->flags & UCX_BUFFER_AUTOFREE) == UCX_BUFFER_AUTOFREE) {
        free(buffer->space);
    }
    free(buffer);
}

UcxBuffer* ucx_buffer_extract(
        UcxBuffer *src, size_t start, size_t length, int flags) {
    if (src->size == 0 || length == 0 ||
        ((size_t)-1) - start < length || start+length > src->capacity)
    {
        return NULL;
    }

    UcxBuffer *dst = (UcxBuffer*) malloc(sizeof(UcxBuffer));
    if (dst) {
        dst->space = (char*)malloc(length);
        if (!dst->space) {
            free(dst);
            return NULL;
        }
        dst->capacity = length;
        dst->size = length;
        dst->flags = flags | UCX_BUFFER_AUTOFREE;
        dst->pos = 0;
        memcpy(dst->space, src->space+start, length);
    }
    return dst;
}

int ucx_buffer_seek(UcxBuffer *buffer, off_t offset, int whence) {
    size_t npos;
    switch (whence) {
    case SEEK_CUR:
        npos = buffer->pos;
        break;
    case SEEK_END:
        npos = buffer->size;
        break;
    case SEEK_SET:
        npos = 0;
        break;
    default:
        return -1;
    }

    size_t opos = npos;
    npos += offset;
    
    if ((offset > 0 && npos < opos) || (offset < 0 && npos > opos)) {
        return -1;
    }
    
    if (npos >= buffer->size) {
        return -1;
    } else {
        buffer->pos = npos;
        return 0;
    }

}

int ucx_buffer_eof(UcxBuffer *buffer) {
    return buffer->pos >= buffer->size;
}

int ucx_buffer_extend(UcxBuffer *buffer, size_t len) {
    size_t newcap = buffer->capacity;
    
    if (buffer->capacity + len < buffer->capacity) {
        return -1;
    }
    
    while (buffer->capacity + len > newcap) {
        newcap <<= 1;
        if (newcap < buffer->capacity) {
            return -1;
        }
    }
    
    char *newspace = (char*)realloc(buffer->space, newcap);
    if (newspace) {
        memset(newspace+buffer->size, 0, newcap-buffer->size);
        buffer->space = newspace;
        buffer->capacity = newcap;
    } else {
        return -1;
    }
    
    return 0;
}

size_t ucx_buffer_write(const void *ptr, size_t size, size_t nitems,
        UcxBuffer *buffer) {
    size_t len;
    if(ucx_szmul(size, nitems, &len)) {
        return 0;
    }
    size_t required = buffer->pos + len;
    if (buffer->pos > required) {
        return 0;
    }
    
    if (required > buffer->capacity) {
        if ((buffer->flags & UCX_BUFFER_AUTOEXTEND) == UCX_BUFFER_AUTOEXTEND) {
            if (ucx_buffer_extend(buffer, required - buffer->capacity)) {
                return 0;
            }
        } else {
            len = buffer->capacity - buffer->pos;
            if (size > 1) {
                len -= len%size;
            }
        }
    }
    
    if (len == 0) {
        return len;
    }
    
    memcpy(buffer->space + buffer->pos, ptr, len);
    buffer->pos += len;
    if(buffer->pos > buffer->size) {
        buffer->size = buffer->pos;
    }
    
    return len / size;
}

size_t ucx_buffer_read(void *ptr, size_t size, size_t nitems,
        UcxBuffer *buffer) {
    size_t len;
    if(ucx_szmul(size, nitems, &len)) {
        return 0;
    }
    if (buffer->pos + len > buffer->size) {
        len = buffer->size - buffer->pos;
        if (size > 1) len -= len%size;
    }
    
    if (len <= 0) {
        return len;
    }
    
    memcpy(ptr, buffer->space + buffer->pos, len);
    buffer->pos += len;
    
    return len / size;
}

int ucx_buffer_putc(UcxBuffer *buffer, int c) {
    if(buffer->pos >= buffer->capacity) {
        if ((buffer->flags & UCX_BUFFER_AUTOEXTEND) == UCX_BUFFER_AUTOEXTEND) {
            if(ucx_buffer_extend(buffer, 1)) {
                return EOF;
            }
        } else {
            return EOF;
        }
    }
    
    c &= 0xFF;
    buffer->space[buffer->pos] = (char) c;
    buffer->pos++;
    if(buffer->pos > buffer->size) {
        buffer->size = buffer->pos;
    }
    return c;
}

int ucx_buffer_getc(UcxBuffer *buffer) {
    if (ucx_buffer_eof(buffer)) {
        return EOF;
    } else {
        int c = ((unsigned char*)buffer->space)[buffer->pos];
        buffer->pos++;
        return c;
    }
}

size_t ucx_buffer_puts(UcxBuffer *buffer, const char *str) {
    return ucx_buffer_write((const void*)str, 1, strlen(str), buffer);
}

int ucx_buffer_shift_left(UcxBuffer* buffer, size_t shift) {
    if (shift >= buffer->size) {
        buffer->pos = buffer->size = 0;
    } else {
        memmove(buffer->space, buffer->space + shift, buffer->size - shift);
        buffer->size -= shift;
        
        if (buffer->pos >= shift) {
            buffer->pos -= shift;
        } else {
            buffer->pos = 0;
        }
    }
    return 0;
}

int ucx_buffer_shift_right(UcxBuffer* buffer, size_t shift) {
    size_t req_capacity = buffer->size + shift;
    size_t movebytes;
    
    // auto extend buffer, if required and enabled
    if (buffer->capacity < req_capacity) {
        if ((buffer->flags & UCX_BUFFER_AUTOEXTEND) == UCX_BUFFER_AUTOEXTEND) {
            if (ucx_buffer_extend(buffer, req_capacity - buffer->capacity)) {
                return 1;
            }
            movebytes = buffer->size;
        } else {
            movebytes = buffer->capacity - shift;
        }
    } else {
        movebytes = buffer->size;
    }
    
    memmove(buffer->space + shift, buffer->space, movebytes);
    buffer->size = shift+movebytes;
    
    buffer->pos += shift;
    if (buffer->pos > buffer->size) {
        buffer->pos = buffer->size;
    }
    
    return 0;
}

int ucx_buffer_shift(UcxBuffer* buffer, off_t shift) {
    if (shift < 0) {
        return ucx_buffer_shift_left(buffer, (size_t) (-shift));
    } else if (shift > 0) {
        return ucx_buffer_shift_right(buffer, (size_t) shift);
    } else {
        return 0;
    }
}