/**
 * @file llstreamtools.cpp
 * @brief some helper functions for parsing legacy simstate and asset files.
 *
 * $LicenseInfo:firstyear=2005&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

#include "linden_common.h"

#include <iostream>
#include <string>

#include "llstreamtools.h"


// ----------------------------------------------------------------------------
// some std::istream helper functions
// ----------------------------------------------------------------------------

// skips spaces and tabs
bool skip_whitespace(std::istream& input_stream)
{
    int c = input_stream.peek();
    while (('\t' == c || ' ' == c) && input_stream.good())
    {
        input_stream.get();
        c = input_stream.peek();
    }
    return input_stream.good();
}

// skips whitespace, newlines, and carriage returns
bool skip_emptyspace(std::istream& input_stream)
{
    int c = input_stream.peek();
    while ( input_stream.good()
            && ('\t' == c || ' ' == c || '\n' == c || '\r' == c) )
    {
        input_stream.get();
        c = input_stream.peek();
    }
    return input_stream.good();
}

// skips emptyspace and lines that start with a #
bool skip_comments_and_emptyspace(std::istream& input_stream)
{
    while (skip_emptyspace(input_stream))
    {
        int c = input_stream.peek();
        if ('#' == c )
        {
            while ('\n' != c && input_stream.good())
            {
                c = input_stream.get();
            }
        }
        else
        {
            break;
        }
    }
    return input_stream.good();
}

bool skip_line(std::istream& input_stream)
{
    int c;
    do
    {
        c = input_stream.get();
    } while ('\n' != c  &&  input_stream.good());
    return input_stream.good();
}

bool skip_to_next_word(std::istream& input_stream)
{
    int c = input_stream.peek();
    while ( input_stream.good()
            && (   (c >= 'a' && c <= 'z')
                || (c >= 'A' && c <= 'Z')
                || (c >= '0' && c <= '9')
                || '_' == c ) )
    {
        input_stream.get();
        c = input_stream.peek();
    }
    while ( input_stream.good()
            && !(   (c >= 'a' && c <= 'z')
                 || (c >= 'A' && c <= 'Z')
                 || (c >= '0' && c <= '9')
                 || '_' == c ) )
    {
        input_stream.get();
        c = input_stream.peek();
    }
    return input_stream.good();
}

bool skip_to_end_of_next_keyword(const char* keyword, std::istream& input_stream)
{
    auto key_length = strlen(keyword);   /*Flawfinder: ignore*/
    if (0 == key_length)
    {
        return false;
    }
    while (input_stream.good())
    {
        skip_emptyspace(input_stream);
        int c = input_stream.get();
        if (keyword[0] != c)
        {
            skip_line(input_stream);
        }
        else
        {
            int key_index = 1;
            while ( key_index < key_length
                    &&  keyword[key_index - 1] == c
                    && input_stream.good())
            {
                key_index++;
                c = input_stream.get();
            }

            if (key_index == key_length
                && keyword[key_index-1] == c)
            {
                c = input_stream.peek();
                if (' ' == c || '\t' == c || '\r' == c || '\n' == c)
                {
                    return true;
                }
                else
                {
                    skip_line(input_stream);
                }
            }
            else
            {
                skip_line(input_stream);
            }
        }
    }
    return false;
}

/* skip_to_start_of_next_keyword() is disabled -- might tickle corruption bug in windows iostream
bool skip_to_start_of_next_keyword(const char* keyword, std::istream& input_stream)
{
    int key_length = strlen(keyword);
    if (0 == key_length)
    {
        return false;
    }
    while (input_stream.good())
    {
        skip_emptyspace(input_stream);
        int c = input_stream.get();
        if (keyword[0] != c)
        {
            skip_line(input_stream);
        }
        else
        {
            int key_index = 1;
            while ( key_index < key_length
                    &&  keyword[key_index - 1] == c
                    && input_stream.good())
            {
                key_index++;
                c = input_stream.get();
            }

            if (key_index == key_length
                && keyword[key_index-1] == c)
            {
                c = input_stream.peek();
                if (' ' == c || '\t' == c || '\r' == c || '\n' == c)
                {
                    // put the keyword back onto the stream
                    for (int index = key_length - 1; index >= 0; index--)
                    {
                        input_stream.putback(keyword[index]);
                    }
                    return true;
                }
                else
                {
                    skip_line(input_stream);
                    break;
                }
            }
            else
            {
                skip_line(input_stream);
            }
        }
    }
    return false;
}
*/

bool get_word(std::string& output_string, std::istream& input_stream)
{
    skip_emptyspace(input_stream);
    int c = input_stream.peek();
    while ( !isspace(c)
            && '\n' != c
            && '\r' != c
            && input_stream.good() )
    {
        output_string += c;
        input_stream.get();
        c = input_stream.peek();
    }
    return input_stream.good();
}

bool get_word(std::string& output_string, std::istream& input_stream, int n)
{
    skip_emptyspace(input_stream);
    int char_count = 0;
    int c = input_stream.peek();
    while (!isspace(c)
            && '\n' != c
            && '\r' != c
            && input_stream.good()
            && char_count < n)
    {
        char_count++;
        output_string += c;
        input_stream.get();
        c = input_stream.peek();
    }
    return input_stream.good();
}

// get everything up to and including the next newline
bool get_line(std::string& output_string, std::istream& input_stream)
{
    output_string.clear();
    int c = input_stream.get();
    while (input_stream.good())
    {
        output_string += c;
        if ('\n' == c)
        {
            break;
        }
        c = input_stream.get();
    }
    return input_stream.good();
}

// get everything up to and including the next newline
// up to the next n characters.
// add a newline on the end if bail before actual line ending
bool get_line(std::string& output_string, std::istream& input_stream, int n)
{
    output_string.clear();
    int char_count = 0;
    int c = input_stream.get();
    while (input_stream.good() && char_count < n)
    {
        char_count++;
        output_string += c;
        if ('\n' == c)
        {
            break;
        }
        if (char_count >= n)
        {
            output_string.append("\n");
            break;
        }
        c = input_stream.get();
    }
    return input_stream.good();
}

/* disabled -- might tickle bug in windows iostream
// backs up the input_stream by line_size + 1 characters
bool unget_line(const std::string& line, std::istream& input_stream)
{
    input_stream.putback('\n'); // unget the newline
    for (int line_index = line.size()-1; line_index >= 0; line_index--)
    {
        input_stream.putback(line[line_index]);
    }
    return input_stream.good();
}
*/

// removes the last char in 'line' if it matches 'c'
// returns true if removed last char
bool remove_last_char(char c, std::string& line)
{
    auto line_size = line.size();
    if (line_size > 1
        && c == line[line_size - 1])
    {
        line.replace(line_size - 1, 1, "");
        return true;
    }
    return false;
}

// replaces escaped characters with the correct characters from left to right
// "\\\\" ---> '\\' (two backslahes become one)
// "\\n" ---> '\n' (backslash n becomes carriage return)
void unescape_string(std::string& line)
{
    auto line_size = line.size();
    for (size_t index = 0; line_size >= 1 && index < line_size - 1; ++index)
    {
        if ('\\' == line[index])
        {
            if ('\\' == line[index + 1])
            {
                line.replace(index, 2, "\\");
                line_size--;
            }
            else if ('n' == line[index + 1])
            {
                line.replace(index, 2, "\n");
                line_size--;
            }
        }
    }
}

// replaces unescaped characters with expanded equivalents from left to right
// '\\' ---> "\\\\" (one backslash becomes two)
// '\n' ---> "\\n"  (carriage return becomes backslash n)
void escape_string(std::string& line)
{
    auto line_size = line.size();
    for (size_t index = 0; index < line_size; ++index)
    {
        if ('\\' == line[index])
        {
            line.replace(index, 1, "\\\\");
            line_size++;
            index++;
        }
        else if ('\n' == line[index])
        {
            line.replace(index, 1, "\\n");
            line_size++;
            index++;
        }
    }
}

// removes '\n' characters
void replace_newlines_with_whitespace(std::string& line)
{
    auto line_size = line.size();
    for (size_t index = 0; index < line_size; ++index)
    {
        if ('\n' == line[index])
        {
            line.replace(index, 1, " ");
        }
    }
}

// erases any double-quote characters in 'line'
void remove_double_quotes(std::string& line)
{
    auto line_size = line.size();
    for (size_t index = 0; index < line_size; )
    {
        if ('"' == line[index])
        {
            int count = 1;
            while (index + count < line_size
                   && '"' == line[index + count])
            {
                count++;
            }
            line.replace(index, count, "");
            line_size -= count;
        }
        else
        {
            index++;
        }
    }
}

// the 'keyword' is defined as the first word on a line
// the 'value' is everything after the keyword on the same line
// starting at the first non-whitespace and ending right before the newline
void get_keyword_and_value(std::string& keyword,
                           std::string& value,
                           const std::string& line)
{
    // skip initial whitespace
    auto line_size = line.size();
    size_t line_index = 0;
    char c;
    for ( ; line_index < line_size; ++line_index)
    {
        c = line[line_index];
        if (!LLStringOps::isSpace(c))
        {
            break;
        }
    }

    // get the keyword
    keyword.clear();
    for ( ; line_index < line_size; ++line_index)
    {
        c = line[line_index];
        if (LLStringOps::isSpace(c) || '\r' == c || '\n' == c)
        {
            break;
        }
        keyword += c;
    }

    // get the value
    value.clear();
    if (keyword.size() > 0
        && '\r' != line[line_index]
        && '\n' != line[line_index])

    {
        // discard initial white spaces
        while (line_index < line_size
                && (' ' == line[line_index]
                    || '\t' == line[line_index]) )
        {
            line_index++;
        }

        for ( ; line_index < line_size; ++line_index)
        {
            c = line[line_index];
            if ('\r' == c || '\n' == c)
            {
                break;
            }
            value += c;
        }
    }
}

std::streamsize fullread(
    std::istream& istr,
    char* buf,
    std::streamsize requested)
{
    std::streamsize got;
    std::streamsize total = 0;

    istr.read(buf, requested);   /*Flawfinder: ignore*/
    got = istr.gcount();
    total += got;
    while(got && total < requested)
    {
        if(istr.fail())
        {
            // If bad is true, not much we can doo -- it implies loss
            // of stream integrity. Bail in that case, and otherwise
            // clear and attempt to continue.
            if(istr.bad()) return total;
            istr.clear();
        }
        istr.read(buf + total, requested - total);   /*Flawfinder: ignore*/
        got = istr.gcount();
        total += got;
    }
    return total;
}

std::istream& operator>>(std::istream& str, const char *tocheck)
{
    char c = '\0';
    const char *p;
    p = tocheck;
    while (*p && !str.bad())
    {
        str.get(c);
        if (c != *p)
        {
            str.setstate(std::ios::failbit);        /*Flawfinder: ignore*/
            break;
        }
        p++;
    }
    return str;
}

int cat_streambuf::underflow()
{
    if (gptr() == egptr())
    {
        // here because our buffer is empty
        std::streamsize size = 0;
        // Until we've run out of mInputs, try reading the first of them
        // into mBuffer. If that fetches some characters, break the loop.
        while (! mInputs.empty()
               && ! (size = mInputs.front()->sgetn(mBuffer.data(), mBuffer.size())))
        {
            // We tried to read mInputs.front() but got zero characters.
            // Discard the first streambuf and try the next one.
            mInputs.pop_front();
        }
        // Either we ran out of mInputs or we succeeded in reading some
        // characters, that is, size != 0. Tell base class what we have.
        setg(mBuffer.data(), mBuffer.data(), mBuffer.data() + size);
    }
    // If we fell out of the above loop with mBuffer still empty, return
    // eof(), otherwise return the next character.
    return (gptr() == egptr())
        ? std::char_traits<char>::eof()
        : std::char_traits<char>::to_int_type(*gptr());
}