/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <limits.h>
#include <string.h>
#include <stdio.h>
#include "readstrings.h"
#include "errors.h"

#ifdef _WIN32
# define NS_tfopen _wfopen
# define OPEN_MODE L"rb"
#else
# define NS_tfopen fopen
# define OPEN_MODE "r"
#endif

// stack based FILE wrapper to ensure that fclose is called.
class AutoFILE
{
public:
    explicit AutoFILE(FILE *fp) : fp_(fp) {}
    ~AutoFILE()
    {
        if (fp_) fclose(fp_);
    }
    operator FILE *()
    {
        return fp_;
    }
private:
    FILE *fp_;
};

class AutoCharArray
{
public:
    explicit AutoCharArray(size_t len)
    {
        ptr_ = new char[len];
    }
    ~AutoCharArray()
    {
        delete[] ptr_;
    }
    operator char *()
    {
        return ptr_;
    }
private:
    char *ptr_;
};

static const char kNL[] = "\r\n";
static const char kEquals[] = "=";
static const char kWhitespace[] = " \t";
static const char kRBracket[] = "]";

static const char*
NS_strspnp(const char *delims, const char *str)
{
    const char *d;
    do
    {
        for (d = delims; *d != '\0'; ++d)
        {
            if (*str == *d)
            {
                ++str;
                break;
            }
        }
    }
    while (*d);

    return str;
}

static char*
NS_strtok(const char *delims, char **str)
{
    if (!*str)
        return nullptr;

    char *ret = (char*) NS_strspnp(delims, *str);

    if (!*ret)
    {
        *str = ret;
        return nullptr;
    }

    char *i = ret;
    do
    {
        for (const char *d = delims; *d != '\0'; ++d)
        {
            if (*i == *d)
            {
                *i = '\0';
                *str = ++i;
                return ret;
            }
        }
        ++i;
    }
    while (*i);

    *str = nullptr;
    return ret;
}

/**
 * Find a key in a keyList containing zero-delimited keys ending with "\0\0".
 * Returns a zero-based index of the key in the list, or -1 if the key is not found.
 */
static int
find_key(const char *keyList, char* key)
{
    if (!keyList)
        return -1;

    int index = 0;
    const char *p = keyList;
    while (*p)
    {
        if (strcmp(key, p) == 0)
            return index;

        p += strlen(p) + 1;
        index++;
    }

    // The key was not found if we came here
    return -1;
}

/**
 * A very basic parser for updater.ini taken mostly from nsINIParser.cpp
 * that can be used by standalone apps.
 *
 * @param path       Path to the .ini file to read
 * @param keyList    List of zero-delimited keys ending with two zero characters
 * @param numStrings Number of strings to read into results buffer - must be equal to the number of keys
 * @param results    Two-dimensional array of strings to be filled in the same order as the keys provided
 * @param section    Optional name of the section to read; defaults to "Strings"
 */
int
ReadStrings(const NS_tchar *path,
            const char *keyList,
            unsigned int numStrings,
            char results[][MAX_TEXT_LEN],
            const char *section)
{
    AutoFILE fp(NS_tfopen(path, OPEN_MODE));

    if (!fp)
        return READ_ERROR;

    /* get file size */
    if (fseek(fp, 0, SEEK_END) != 0)
        return READ_ERROR;

    long len = ftell(fp);
    if (len <= 0)
        return READ_ERROR;

    size_t flen = size_t(len);
    AutoCharArray fileContents(flen + 1);
    if (!fileContents)
        return READ_STRINGS_MEM_ERROR;

    /* read the file in one swoop */
    if (fseek(fp, 0, SEEK_SET) != 0)
        return READ_ERROR;

    size_t rd = fread(fileContents, sizeof(char), flen, fp);
    if (rd != flen)
        return READ_ERROR;

    fileContents[flen] = '\0';

    char *buffer = fileContents;
    bool inStringsSection = false;

    unsigned int read = 0;

    while (char *token = NS_strtok(kNL, &buffer))
    {
        if (token[0] == '#' || token[0] == ';') // it's a comment
            continue;

        token = (char*) NS_strspnp(kWhitespace, token);
        if (!*token) // empty line
            continue;

        if (token[0] == '[')   // section header!
        {
            ++token;
            char const * currSection = token;

            char *rb = NS_strtok(kRBracket, &token);
            if (!rb || NS_strtok(kWhitespace, &token))
            {
                // there's either an unclosed [Section or a [Section]Moretext!
                // we could frankly decide that this INI file is malformed right
                // here and stop, but we won't... keep going, looking for
                // a well-formed [section] to continue working with
                inStringsSection = false;
            }
            else
            {
                if (section)
                    inStringsSection = strcmp(currSection, section) == 0;
                else
                    inStringsSection = strcmp(currSection, "Strings") == 0;
            }

            continue;
        }

        if (!inStringsSection)
        {
            // If we haven't found a section header (or we found a malformed
            // section header), or this isn't the [Strings] section don't bother
            // parsing this line.
            continue;
        }

        char *key = token;
        char *e = NS_strtok(kEquals, &token);
        if (!e)
            continue;

        int keyIndex = find_key(keyList, key);
        if (keyIndex >= 0 && (unsigned int)keyIndex < numStrings)
        {
            strncpy(results[keyIndex], token, MAX_TEXT_LEN - 1);
            results[keyIndex][MAX_TEXT_LEN - 1] = '\0';
            read++;
        }
    }

    return (read == numStrings) ? OK : PARSE_ERROR;
}

// A wrapper function to read strings for the updater.
// Added for compatibility with the original code.
int
ReadStrings(const NS_tchar *path, StringTable *results)
{
    const unsigned int kNumStrings = 2;
    const char *kUpdaterKeys = "Title\0Info\0";
    char updater_strings[kNumStrings][MAX_TEXT_LEN];

    int result = ReadStrings(path, kUpdaterKeys, kNumStrings, updater_strings);

    strncpy(results->title, updater_strings[0], MAX_TEXT_LEN - 1);
    results->title[MAX_TEXT_LEN - 1] = '\0';
    strncpy(results->info, updater_strings[1], MAX_TEXT_LEN - 1);
    results->info[MAX_TEXT_LEN - 1] = '\0';

    return result;
}