gecko-dev/intl/strres/nsStringBundleTextOverride.cpp

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* 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 "nsStringBundleTextOverride.h"
#include "nsString.h"

#include "nsNetUtil.h"
#include "nsAppDirectoryServiceDefs.h"
#include "nsContentUtils.h"

// first we need a simple class which wraps a nsIPropertyElement and
// cuts out the leading URL from the key
class URLPropertyElement : public nsIPropertyElement
{
public:
    URLPropertyElement(nsIPropertyElement *aRealElement, uint32_t aURLLength) :
        mRealElement(aRealElement),
        mURLLength(aURLLength)
    { }

    NS_DECL_ISUPPORTS
    NS_DECL_NSIPROPERTYELEMENT

private:
    nsCOMPtr<nsIPropertyElement> mRealElement;
    uint32_t mURLLength;

    virtual ~URLPropertyElement() {}
};

NS_IMPL_ISUPPORTS(URLPropertyElement, nsIPropertyElement)

// we'll tweak the key on the way through, and remove the url prefix
NS_IMETHODIMP
URLPropertyElement::GetKey(nsACString& aKey)
{
    nsresult rv =  mRealElement->GetKey(aKey);
    if (NS_FAILED(rv)) return rv;

    // chop off the url
    aKey.Cut(0, mURLLength);
    
    return NS_OK;
}

// values are unaffected
NS_IMETHODIMP
URLPropertyElement::GetValue(nsAString& aValue)
{
    return mRealElement->GetValue(aValue);
}

// setters are kind of strange, hopefully we'll never be called
NS_IMETHODIMP
URLPropertyElement::SetKey(const nsACString& aKey)
{
    // this is just wrong - ideally you'd take the key, append it to
    // the url, and set that as the key. However, that would require
    // us to hold onto a copy of the string, and that's a waste,
    // considering nobody should ever be calling this.
    NS_ERROR("This makes no sense!");
    return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
URLPropertyElement::SetValue(const nsAString& aValue)
{
    return mRealElement->SetValue(aValue);
}


// this is a special enumerator which returns only the elements which
// are prefixed with a particular url
class nsPropertyEnumeratorByURL : public nsISimpleEnumerator
{
public:
    nsPropertyEnumeratorByURL(const nsACString& aURL,
                              nsISimpleEnumerator* aOuter) :
        mOuter(aOuter),
        mURL(aURL)
    {
        // prepare the url once so we can use its value later
        // persistent properties uses ":" as a delimiter, so escape
        // that character
        mURL.ReplaceSubstring(":", "%3A");
        // there is always a # between the url and the real key
        mURL.Append('#');
    }

    NS_DECL_ISUPPORTS
    NS_DECL_NSISIMPLEENUMERATOR

private:

    // actual enumerator of all strings from nsIProperties
    nsCOMPtr<nsISimpleEnumerator> mOuter;

    // the current element that is valid for this url
    nsCOMPtr<nsIPropertyElement> mCurrent;

    // the url in question, pre-escaped and with the # already in it
    nsCString mURL;

    virtual ~nsPropertyEnumeratorByURL() {}
};

//
// nsStringBundleTextOverride implementation
//
NS_IMPL_ISUPPORTS(nsStringBundleTextOverride,
                  nsIStringBundleOverride)

nsresult
nsStringBundleTextOverride::Init()
{
    nsresult rv;

    // check for existence of custom-strings.txt

    nsCOMPtr<nsIFile> customStringsFile;
    rv = NS_GetSpecialDirectory(NS_APP_CHROME_DIR,
                                getter_AddRefs(customStringsFile));

    if (NS_FAILED(rv)) return rv;

    // bail if not found - this will cause the service creation to
    // bail as well, and cause this object to go away

    customStringsFile->AppendNative(NS_LITERAL_CSTRING("custom-strings.txt"));

    bool exists;
    rv = customStringsFile->Exists(&exists);
    if (NS_FAILED(rv) || !exists)
        return NS_ERROR_FAILURE;

    NS_WARNING("Using custom-strings.txt to override string bundles.");
    // read in the custom bundle. Keys are in the form
    // chrome://package/locale/foo.properties:keyname

    nsAutoCString customStringsURLSpec;
    rv = NS_GetURLSpecFromFile(customStringsFile, customStringsURLSpec);
    if (NS_FAILED(rv)) return rv;
    
    nsCOMPtr<nsIURI> uri;
    rv = NS_NewURI(getter_AddRefs(uri), customStringsURLSpec);
    NS_ENSURE_SUCCESS(rv, rv);

    nsCOMPtr<nsIChannel> channel;
    rv = NS_NewChannel(getter_AddRefs(channel),
                       uri,
                       nsContentUtils::GetSystemPrincipal(),
                       nsILoadInfo::SEC_NORMAL,
                       nsIContentPolicy::TYPE_OTHER);

    NS_ENSURE_SUCCESS(rv, rv);
    nsCOMPtr<nsIInputStream> in;
    rv = channel->Open(getter_AddRefs(in));
    NS_ENSURE_SUCCESS(rv, rv);

    static NS_DEFINE_CID(kPersistentPropertiesCID, NS_IPERSISTENTPROPERTIES_CID);
    mValues = do_CreateInstance(kPersistentPropertiesCID, &rv);
    if (NS_FAILED(rv)) return rv;

    rv = mValues->Load(in);

    // turn this on to see the contents of custom-strings.txt
#ifdef DEBUG_alecf
    nsCOMPtr<nsISimpleEnumerator> enumerator;
    mValues->Enumerate(getter_AddRefs(enumerator));
    NS_ASSERTION(enumerator, "no enumerator!\n");
    
    printf("custom-strings.txt contains:\n");
    printf("----------------------------\n");

    bool hasMore;
    enumerator->HasMoreElements(&hasMore);
    do {
        nsCOMPtr<nsISupports> sup;
        enumerator->GetNext(getter_AddRefs(sup));

        nsCOMPtr<nsIPropertyElement> prop = do_QueryInterface(sup);

        nsAutoCString key;
        nsAutoString value;
        prop->GetKey(key);
        prop->GetValue(value);

        printf("%s = '%s'\n", key.get(), NS_ConvertUTF16toUTF8(value).get());

        enumerator->HasMoreElements(&hasMore);
    } while (hasMore);
#endif
    
    return rv;
}

NS_IMETHODIMP
nsStringBundleTextOverride::GetStringFromName(const nsACString& aURL,
                                              const nsACString& key,
                                              nsAString& aResult)
{
    // concatenate url#key to get the key to read
    nsAutoCString combinedURL(aURL + NS_LITERAL_CSTRING("#") + key);

    // persistent properties uses ":" as a delimiter, so escape that character
    combinedURL.ReplaceSubstring(":", "%3A");

    return mValues->GetStringProperty(combinedURL, aResult);
}

NS_IMETHODIMP
nsStringBundleTextOverride::EnumerateKeysInBundle(const nsACString& aURL,
                                                  nsISimpleEnumerator** aResult)
{
    // enumerate all strings, and let the enumerator know
    nsCOMPtr<nsISimpleEnumerator> enumerator;
    mValues->Enumerate(getter_AddRefs(enumerator));

    // make the enumerator wrapper and pass it off
    nsPropertyEnumeratorByURL* propEnum =
        new nsPropertyEnumeratorByURL(aURL, enumerator);

    if (!propEnum) return NS_ERROR_OUT_OF_MEMORY;
    
    NS_ADDREF(*aResult = propEnum);
    
    return NS_OK;
}


//
// nsPropertyEnumeratorByURL implementation
//


NS_IMPL_ISUPPORTS(nsPropertyEnumeratorByURL, nsISimpleEnumerator)

NS_IMETHODIMP
nsPropertyEnumeratorByURL::GetNext(nsISupports **aResult)
{
    if (!mCurrent) return NS_ERROR_UNEXPECTED;

    // wrap mCurrent instead of returning it
    *aResult = new URLPropertyElement(mCurrent, mURL.Length());
    NS_ADDREF(*aResult);

    // release it so we don't return it twice
    mCurrent = nullptr;
    
    return NS_OK;
}

NS_IMETHODIMP
nsPropertyEnumeratorByURL::HasMoreElements(bool * aResult)
{
    bool hasMore;
    mOuter->HasMoreElements(&hasMore);
    while (hasMore) {

        nsCOMPtr<nsISupports> supports;
        mOuter->GetNext(getter_AddRefs(supports));

        mCurrent = do_QueryInterface(supports);

        if (mCurrent) {
            nsAutoCString curKey;
            mCurrent->GetKey(curKey);
        
            if (StringBeginsWith(curKey, mURL))
                break;
        }
        
        mOuter->HasMoreElements(&hasMore);
    }

    if (!hasMore)
        mCurrent = nullptr;
    
    *aResult = mCurrent ? true : false;
    
    return NS_OK;
}