/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla code.
 *
 * The Initial Developer of the Original Code is
 * Mozilla Corporation.
 * Portions created by the Initial Developer are Copyright (C) 2011
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Taras Glek <tglek@mozilla.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include "base/histogram.h"
#include "nsIComponentManager.h"
#include "nsIServiceManager.h"
#include "nsCOMPtr.h"
#include "mozilla/ModuleUtils.h"
#include "nsIXPConnect.h"
#include "mozilla/Services.h"
#include "jsapi.h" 
#include "nsStringGlue.h"
#include "nsITelemetry.h"
#include "Telemetry.h" 
#include <map>
#include <string.h>

namespace {

using namespace base;
using namespace mozilla;
using namespace std;

struct ltstr {
  bool operator()(const char* s1, const char* s2) const {
    return strcmp(s1, s2) < 0;
  }
};

class TelemetryImpl : public nsITelemetry
{
  NS_DECL_ISUPPORTS
  NS_DECL_NSITELEMETRY

public:

private:
  // This is used to cache JS string->Telemetry::ID conversions
  typedef map<const char*, Telemetry::ID, ltstr> NameHistogramMap;
  NameHistogramMap mHistogramMap;
};

// A initializer to initialize histogram collection
StatisticsRecorder gStatisticsRecorder;

// Hardcoded probes
struct TelemetryHistogram {
  Histogram *histogram;
  const char *id;
  PRUint32 min;
  PRUint32 max;
  PRUint32 bucketCount;
  PRUint32 histogramType;
};

const TelemetryHistogram gHistograms[] = {
#define HISTOGRAM(id, min, max, bucket_count, histogram_type, b) \
  { NULL, NS_STRINGIFY(id), min, max, bucket_count, nsITelemetry::HISTOGRAM_ ## histogram_type },

#include "TelemetryHistograms.h"

#undef HISTOGRAM
};

nsresult
HistogramGet(const char *name, PRUint32 min, PRUint32 max, PRUint32 bucketCount,
             PRUint32 histogramType, Histogram **result)
{
  if (histogramType != nsITelemetry::HISTOGRAM_BOOLEAN) {
    // Sanity checks for histogram parameters.
    if (min >= max)
      return NS_ERROR_ILLEGAL_VALUE;

    if (bucketCount <= 2)
      return NS_ERROR_ILLEGAL_VALUE;

    if (min < 1)
      return NS_ERROR_ILLEGAL_VALUE;
  }

  switch (histogramType) {
  case nsITelemetry::HISTOGRAM_EXPONENTIAL:
    *result = Histogram::FactoryGet(name, min, max, bucketCount, Histogram::kNoFlags);
    break;
  case nsITelemetry::HISTOGRAM_LINEAR:
    *result = LinearHistogram::FactoryGet(name, min, max, bucketCount, Histogram::kNoFlags);
    break;
  case nsITelemetry::HISTOGRAM_BOOLEAN:
    *result = BooleanHistogram::FactoryGet(name, Histogram::kNoFlags);
    break;
  default:
    return NS_ERROR_INVALID_ARG;
  }
  return NS_OK;
}

// O(1) histogram lookup by numeric id
nsresult
GetHistogramByEnumId(Telemetry::ID id, Histogram **ret)
{
  static Histogram* knownHistograms[Telemetry::HistogramCount] = {0};
  Histogram *h = knownHistograms[id];
  if (h) {
    *ret = h;
    return NS_OK;
  }

  const TelemetryHistogram &p = gHistograms[id];
  nsresult rv = HistogramGet(p.id, p.min, p.max, p.bucketCount, p.histogramType, &h);
  if (NS_FAILED(rv))
    return NS_ERROR_FAILURE;

  *ret = knownHistograms[id] = h;
  return NS_OK;
}

bool
FillRanges(JSContext *cx, JSObject *array, Histogram *h)
{
  for (size_t i = 0; i < h->bucket_count(); i++) {
    if (!JS_DefineElement(cx, array, i, INT_TO_JSVAL(h->ranges(i)), NULL, NULL, JSPROP_ENUMERATE))
      return false;
  }
  return true;
}

JSBool
ReflectHistogramSnapshot(JSContext *cx, JSObject *obj, Histogram *h)
{
  Histogram::SampleSet ss;
  h->SnapshotSample(&ss);
  JSObject *counts_array;
  JSObject *rarray;
  const size_t count = h->bucket_count();
  if (!(JS_DefineProperty(cx, obj, "min", INT_TO_JSVAL(h->declared_min()), NULL, NULL, JSPROP_ENUMERATE)
        && JS_DefineProperty(cx, obj, "max", INT_TO_JSVAL(h->declared_max()), NULL, NULL, JSPROP_ENUMERATE)
        && JS_DefineProperty(cx, obj, "histogram_type", INT_TO_JSVAL(h->histogram_type()), NULL, NULL, JSPROP_ENUMERATE)
        && JS_DefineProperty(cx, obj, "sum", INT_TO_JSVAL(ss.sum()), NULL, NULL, JSPROP_ENUMERATE)
        && (rarray = JS_NewArrayObject(cx, count, NULL))
        && JS_DefineProperty(cx, obj, "ranges", OBJECT_TO_JSVAL(rarray), NULL, NULL, JSPROP_ENUMERATE)
        && FillRanges(cx, rarray, h)
        && (counts_array = JS_NewArrayObject(cx, count, NULL))
        && JS_DefineProperty(cx, obj, "counts", OBJECT_TO_JSVAL(counts_array), NULL, NULL, JSPROP_ENUMERATE)
        )) {
    return JS_FALSE;
  }
  for (size_t i = 0; i < count; i++) {
    if (!JS_DefineElement(cx, counts_array, i, INT_TO_JSVAL(ss.counts(i)), NULL, NULL, JSPROP_ENUMERATE)) {
      return JS_FALSE;
    }
  }
  return JS_TRUE;
}

JSBool
JSHistogram_Add(JSContext *cx, uintN argc, jsval *vp)
{
  jsval *argv = JS_ARGV(cx, vp);
  JSString *str;
  if (!JS_ConvertArguments(cx, argc, argv, "i", &str))
    return JS_FALSE;
  if (!JSVAL_IS_INT(argv[0]))
    return JS_FALSE;
  JSObject *obj = JS_THIS_OBJECT(cx, vp);
  Histogram *h = static_cast<Histogram*>(JS_GetPrivate(cx, obj));
  PRUint32 value = JSVAL_TO_INT(argv[0]);
  if (h->histogram_type() == Histogram::BOOLEAN_HISTOGRAM)
    h->Add(!!value);
  else
    h->Add(value);
  return JS_TRUE;
}

JSBool
JSHistogram_Snapshot(JSContext *cx, uintN argc, jsval *vp)
{
  JSObject *obj = JS_THIS_OBJECT(cx, vp);
  Histogram *h = static_cast<Histogram*>(JS_GetPrivate(cx, obj));
  JSObject *snapshot = JS_NewObject(cx, NULL, NULL, NULL);
  if (!snapshot)
    return NS_ERROR_FAILURE;
  JS_SET_RVAL(cx, vp, OBJECT_TO_JSVAL(snapshot));
  return ReflectHistogramSnapshot(cx, snapshot, h);
}

nsresult 
WrapAndReturnHistogram(Histogram *h, JSContext *cx, jsval *ret)
{
  static JSClass JSHistogram_class = {
    "JSHistogram",  /* name */
    JSCLASS_HAS_PRIVATE, /* flags */
    JS_PropertyStub, JS_PropertyStub, JS_PropertyStub, JS_StrictPropertyStub,
    JS_EnumerateStub, JS_ResolveStub, JS_ConvertStub, JS_FinalizeStub,
    JSCLASS_NO_OPTIONAL_MEMBERS
  };

  JSObject *obj = JS_NewObject(cx, &JSHistogram_class, NULL, NULL);
  if (!obj)
    return NS_ERROR_FAILURE;
  *ret = OBJECT_TO_JSVAL(obj);
  return (JS_SetPrivate(cx, obj, h)
          && JS_DefineFunction (cx, obj, "add", JSHistogram_Add, 1, 0)
          && JS_DefineFunction (cx, obj, "snapshot", JSHistogram_Snapshot, 1, 0)) ? NS_OK : NS_ERROR_FAILURE;
}

NS_IMETHODIMP
TelemetryImpl::NewHistogram(const nsACString &name, PRUint32 min, PRUint32 max, PRUint32 bucketCount, PRUint32 histogramType, JSContext *cx, jsval *ret)
{
  Histogram *h;
  nsresult rv = HistogramGet(PromiseFlatCString(name).get(), min, max, bucketCount, histogramType, &h);
  if (NS_FAILED(rv))
    return rv;
  return WrapAndReturnHistogram(h, cx, ret);
}

NS_IMETHODIMP
TelemetryImpl::GetHistogramSnapshots(JSContext *cx, jsval *ret)
{
  JSObject *root_obj = JS_NewObject(cx, NULL, NULL, NULL);
  if (!root_obj)
    return NS_ERROR_FAILURE;
  *ret = OBJECT_TO_JSVAL(root_obj);

  StatisticsRecorder::Histograms h;
  StatisticsRecorder::GetHistograms(&h);
  for (StatisticsRecorder::Histograms::iterator it = h.begin(); it != h.end();++it) {
    Histogram *h = *it;
    JSObject *hobj = JS_NewObject(cx, NULL, NULL, NULL);
    if (!(hobj
          && JS_DefineProperty(cx, root_obj, h->histogram_name().c_str(),
                               OBJECT_TO_JSVAL(hobj), NULL, NULL, JSPROP_ENUMERATE)
          && ReflectHistogramSnapshot(cx, hobj, h))) {
      return NS_ERROR_FAILURE;
    }
  }
  return NS_OK;
}


NS_IMETHODIMP
TelemetryImpl::GetHistogramById(const nsACString &name, JSContext *cx, jsval *ret)
{
  // Cache names for log(N) lookup
  // Note the histogram names are statically allocated
  if (Telemetry::HistogramCount && !mHistogramMap.size()) {
    for (PRUint32 i = 0; i < Telemetry::HistogramCount; i++) {
      mHistogramMap[gHistograms[i].id] = (Telemetry::ID) i;
    }
  }

  NameHistogramMap::iterator it = mHistogramMap.find(PromiseFlatCString(name).get());
  if (it == mHistogramMap.end())
    return NS_ERROR_FAILURE;
  
  Histogram *h;
  nsresult rv = GetHistogramByEnumId(it->second, &h);
  if (NS_FAILED(rv))
    return rv;

  return WrapAndReturnHistogram(h, cx, ret);
}

NS_IMPL_THREADSAFE_ISUPPORTS1(TelemetryImpl, nsITelemetry)

already_AddRefed<nsITelemetry>
CreateTelemetryInstance()
{
  nsCOMPtr<nsITelemetry> telemetry = new TelemetryImpl();
  return telemetry.forget();
}

NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(nsITelemetry, CreateTelemetryInstance)

#define NS_TELEMETRY_CID \
  {0xaea477f2, 0xb3a2, 0x469c, {0xaa, 0x29, 0x0a, 0x82, 0xd1, 0x32, 0xb8, 0x29}}
NS_DEFINE_NAMED_CID(NS_TELEMETRY_CID);

const Module::CIDEntry kTelemetryCIDs[] = {
  { &kNS_TELEMETRY_CID, false, NULL, nsITelemetryConstructor },
  { NULL }
};

const Module::ContractIDEntry kTelemetryContracts[] = {
  { "@mozilla.org/base/telemetry;1", &kNS_TELEMETRY_CID },
  { NULL }
};

const Module kTelemetryModule = {
  Module::kVersion,
  kTelemetryCIDs,
  kTelemetryContracts,
  NULL,
  NULL,
  NULL,
  NULL,
};

} // anonymous namespace

namespace mozilla {
namespace Telemetry {

void
Accumulate(ID aHistogram, PRUint32 aSample)
{
  Histogram *h;
  nsresult rv = GetHistogramByEnumId(aHistogram, &h);
  if (NS_SUCCEEDED(rv))
    h->Add(aSample);
}

} // namespace Telemetry
} // namespace mozilla

NSMODULE_DEFN(nsTelemetryModule) = &kTelemetryModule;