// Copyright 2017 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_INTL_SUPPORT
#error Internationalization is expected to be enabled.
#endif  // V8_INTL_SUPPORT

#include "src/builtins/builtins-intl.h"
#include "src/builtins/builtins-utils.h"
#include "src/builtins/builtins.h"
#include "src/intl.h"
#include "src/objects-inl.h"
#include "src/objects/intl-objects.h"

#include "unicode/decimfmt.h"
#include "unicode/fieldpos.h"
#include "unicode/fpositer.h"
#include "unicode/normalizer2.h"
#include "unicode/numfmt.h"
#include "unicode/ufieldpositer.h"
#include "unicode/unistr.h"
#include "unicode/ustring.h"

namespace v8 {
namespace internal {

BUILTIN(StringPrototypeToUpperCaseIntl) {
  HandleScope scope(isolate);
  TO_THIS_STRING(string, "String.prototype.toUpperCase");
  string = String::Flatten(string);
  return ConvertCase(string, true, isolate);
}

BUILTIN(StringPrototypeNormalizeIntl) {
  HandleScope handle_scope(isolate);
  TO_THIS_STRING(string, "String.prototype.normalize");

  Handle<Object> form_input = args.atOrUndefined(isolate, 1);
  const char* form_name;
  UNormalization2Mode form_mode;
  if (form_input->IsUndefined(isolate)) {
    // default is FNC
    form_name = "nfc";
    form_mode = UNORM2_COMPOSE;
  } else {
    Handle<String> form;
    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, form,
                                       Object::ToString(isolate, form_input));

    if (String::Equals(form, isolate->factory()->NFC_string())) {
      form_name = "nfc";
      form_mode = UNORM2_COMPOSE;
    } else if (String::Equals(form, isolate->factory()->NFD_string())) {
      form_name = "nfc";
      form_mode = UNORM2_DECOMPOSE;
    } else if (String::Equals(form, isolate->factory()->NFKC_string())) {
      form_name = "nfkc";
      form_mode = UNORM2_COMPOSE;
    } else if (String::Equals(form, isolate->factory()->NFKD_string())) {
      form_name = "nfkc";
      form_mode = UNORM2_DECOMPOSE;
    } else {
      Handle<String> valid_forms =
          isolate->factory()->NewStringFromStaticChars("NFC, NFD, NFKC, NFKD");
      THROW_NEW_ERROR_RETURN_FAILURE(
          isolate,
          NewRangeError(MessageTemplate::kNormalizationForm, valid_forms));
    }
  }

  int length = string->length();
  string = String::Flatten(string);
  icu::UnicodeString result;
  std::unique_ptr<uc16[]> sap;
  UErrorCode status = U_ZERO_ERROR;
  {
    DisallowHeapAllocation no_gc;
    String::FlatContent flat = string->GetFlatContent();
    const UChar* src = GetUCharBufferFromFlat(flat, &sap, length);
    icu::UnicodeString input(false, src, length);
    // Getting a singleton. Should not free it.
    const icu::Normalizer2* normalizer =
        icu::Normalizer2::getInstance(nullptr, form_name, form_mode, status);
    DCHECK(U_SUCCESS(status));
    CHECK(normalizer != nullptr);
    int32_t normalized_prefix_length =
        normalizer->spanQuickCheckYes(input, status);
    // Quick return if the input is already normalized.
    if (length == normalized_prefix_length) return *string;
    icu::UnicodeString unnormalized =
        input.tempSubString(normalized_prefix_length);
    // Read-only alias of the normalized prefix.
    result.setTo(false, input.getBuffer(), normalized_prefix_length);
    // copy-on-write; normalize the suffix and append to |result|.
    normalizer->normalizeSecondAndAppend(result, unnormalized, status);
  }

  if (U_FAILURE(status)) {
    return isolate->heap()->undefined_value();
  }

  RETURN_RESULT_OR_FAILURE(
      isolate, isolate->factory()->NewStringFromTwoByte(Vector<const uint16_t>(
                   reinterpret_cast<const uint16_t*>(result.getBuffer()),
                   result.length())));
}

namespace {

// The list comes from third_party/icu/source/i18n/unicode/unum.h.
// They're mapped to NumberFormat part types mentioned throughout
// https://tc39.github.io/ecma402/#sec-partitionnumberpattern .
Handle<String> IcuNumberFieldIdToNumberType(int32_t field_id, double number,
                                            Isolate* isolate) {
  switch (static_cast<UNumberFormatFields>(field_id)) {
    case UNUM_INTEGER_FIELD:
      if (std::isfinite(number)) return isolate->factory()->integer_string();
      if (std::isnan(number)) return isolate->factory()->nan_string();
      return isolate->factory()->infinity_string();
    case UNUM_FRACTION_FIELD:
      return isolate->factory()->fraction_string();
    case UNUM_DECIMAL_SEPARATOR_FIELD:
      return isolate->factory()->decimal_string();
    case UNUM_GROUPING_SEPARATOR_FIELD:
      return isolate->factory()->group_string();
    case UNUM_CURRENCY_FIELD:
      return isolate->factory()->currency_string();
    case UNUM_PERCENT_FIELD:
      return isolate->factory()->percentSign_string();
    case UNUM_SIGN_FIELD:
      return number < 0 ? isolate->factory()->minusSign_string()
                        : isolate->factory()->plusSign_string();

    case UNUM_EXPONENT_SYMBOL_FIELD:
    case UNUM_EXPONENT_SIGN_FIELD:
    case UNUM_EXPONENT_FIELD:
      // We should never get these because we're not using any scientific
      // formatter.
      UNREACHABLE();
      return Handle<String>();

    case UNUM_PERMILL_FIELD:
      // We're not creating any permill formatter, and it's not even clear how
      // that would be possible with the ICU API.
      UNREACHABLE();
      return Handle<String>();

    default:
      UNREACHABLE();
      return Handle<String>();
  }
}

bool AddElement(Handle<JSArray> array, int index,
                Handle<String> field_type_string,
                const icu::UnicodeString& formatted, int32_t begin, int32_t end,
                Isolate* isolate) {
  HandleScope scope(isolate);
  Factory* factory = isolate->factory();
  Handle<JSObject> element = factory->NewJSObject(isolate->object_function());
  Handle<String> value;
  JSObject::AddProperty(element, factory->type_string(), field_type_string,
                        NONE);

  icu::UnicodeString field(formatted.tempSubStringBetween(begin, end));
  ASSIGN_RETURN_ON_EXCEPTION_VALUE(
      isolate, value,
      factory->NewStringFromTwoByte(Vector<const uint16_t>(
          reinterpret_cast<const uint16_t*>(field.getBuffer()),
          field.length())),
      false);

  JSObject::AddProperty(element, factory->value_string(), value, NONE);
  RETURN_ON_EXCEPTION_VALUE(
      isolate, JSObject::AddDataElement(array, index, element, NONE), false);
  return true;
}

bool cmp_NumberFormatSpan(const NumberFormatSpan& a,
                          const NumberFormatSpan& b) {
  // Regions that start earlier should be encountered earlier.
  if (a.begin_pos < b.begin_pos) return true;
  if (a.begin_pos > b.begin_pos) return false;
  // For regions that start in the same place, regions that last longer should
  // be encountered earlier.
  if (a.end_pos < b.end_pos) return false;
  if (a.end_pos > b.end_pos) return true;
  // For regions that are exactly the same, one of them must be the "literal"
  // backdrop we added, which has a field_id of -1, so consider higher field_ids
  // to be later.
  return a.field_id < b.field_id;
}

Object* FormatNumberToParts(Isolate* isolate, icu::NumberFormat* fmt,
                            double number) {
  Factory* factory = isolate->factory();

  icu::UnicodeString formatted;
  icu::FieldPositionIterator fp_iter;
  UErrorCode status = U_ZERO_ERROR;
  fmt->format(number, formatted, &fp_iter, status);
  if (U_FAILURE(status)) return isolate->heap()->undefined_value();

  Handle<JSArray> result = factory->NewJSArray(0);
  int32_t length = formatted.length();
  if (length == 0) return *result;

  std::vector<NumberFormatSpan> regions;
  // Add a "literal" backdrop for the entire string. This will be used if no
  // other region covers some part of the formatted string. It's possible
  // there's another field with exactly the same begin and end as this backdrop,
  // in which case the backdrop's field_id of -1 will give it lower priority.
  regions.push_back(NumberFormatSpan(-1, 0, formatted.length()));

  {
    icu::FieldPosition fp;
    while (fp_iter.next(fp)) {
      regions.push_back(NumberFormatSpan(fp.getField(), fp.getBeginIndex(),
                                         fp.getEndIndex()));
    }
  }

  std::vector<NumberFormatSpan> parts = FlattenRegionsToParts(&regions);

  int index = 0;
  for (auto it = parts.begin(); it < parts.end(); it++) {
    NumberFormatSpan part = *it;
    Handle<String> field_type_string =
        part.field_id == -1
            ? isolate->factory()->literal_string()
            : IcuNumberFieldIdToNumberType(part.field_id, number, isolate);
    if (!AddElement(result, index, field_type_string, formatted, part.begin_pos,
                    part.end_pos, isolate)) {
      return isolate->heap()->undefined_value();
    }
    ++index;
  }
  JSObject::ValidateElements(*result);

  return *result;
}
}  // namespace

// Flattens a list of possibly-overlapping "regions" to a list of
// non-overlapping "parts". At least one of the input regions must span the
// entire space of possible indexes. The regions parameter will sorted in-place
// according to some criteria; this is done for performance to avoid copying the
// input.
std::vector<NumberFormatSpan> FlattenRegionsToParts(
    std::vector<NumberFormatSpan>* regions) {
  // The intention of this algorithm is that it's used to translate ICU "fields"
  // to JavaScript "parts" of a formatted string. Each ICU field and JavaScript
  // part has an integer field_id, which corresponds to something like "grouping
  // separator", "fraction", or "percent sign", and has a begin and end
  // position. Here's a diagram of:

  // var nf = new Intl.NumberFormat(['de'], {style:'currency',currency:'EUR'});
  // nf.formatToParts(123456.78);

  //               :       6
  //  input regions:    0000000211 7
  // ('-' means -1):    ------------
  // formatted string: "123.456,78 €"
  // output parts:      0006000211-7

  // To illustrate the requirements of this algorithm, here's a contrived and
  // convoluted example of inputs and expected outputs:

  //              :          4
  //              :      22 33    3
  //              :      11111   22
  // input regions:     0000000  111
  //              :     ------------
  // formatted string: "abcdefghijkl"
  // output parts:      0221340--231
  // (The characters in the formatted string are irrelevant to this function.)

  // We arrange the overlapping input regions like a mountain range where
  // smaller regions are "on top" of larger regions, and we output a birds-eye
  // view of the mountains, so that smaller regions take priority over larger
  // regions.
  std::sort(regions->begin(), regions->end(), cmp_NumberFormatSpan);
  std::vector<size_t> overlapping_region_index_stack;
  // At least one item in regions must be a region spanning the entire string.
  // Due to the sorting above, the first item in the vector will be one of them.
  overlapping_region_index_stack.push_back(0);
  NumberFormatSpan top_region = regions->at(0);
  size_t region_iterator = 1;
  int32_t entire_size = top_region.end_pos;

  std::vector<NumberFormatSpan> out_parts;

  // The "climber" is a cursor that advances from left to right climbing "up"
  // and "down" the mountains. Whenever the climber moves to the right, that
  // represents an item of output.
  int32_t climber = 0;
  while (climber < entire_size) {
    int32_t next_region_begin_pos;
    if (region_iterator < regions->size()) {
      next_region_begin_pos = regions->at(region_iterator).begin_pos;
    } else {
      // finish off the rest of the input by proceeding to the end.
      next_region_begin_pos = entire_size;
    }

    if (climber < next_region_begin_pos) {
      while (top_region.end_pos < next_region_begin_pos) {
        if (climber < top_region.end_pos) {
          // step down
          out_parts.push_back(NumberFormatSpan(top_region.field_id, climber,
                                               top_region.end_pos));
          climber = top_region.end_pos;
        } else {
          // drop down
        }
        overlapping_region_index_stack.pop_back();
        top_region = regions->at(overlapping_region_index_stack.back());
      }
      if (climber < next_region_begin_pos) {
        // cross a plateau/mesa/valley
        out_parts.push_back(NumberFormatSpan(top_region.field_id, climber,
                                             next_region_begin_pos));
        climber = next_region_begin_pos;
      }
    }
    if (region_iterator < regions->size()) {
      overlapping_region_index_stack.push_back(region_iterator++);
      top_region = regions->at(overlapping_region_index_stack.back());
    }
  }
  return out_parts;
}

BUILTIN(NumberFormatPrototypeFormatToParts) {
  const char* const method = "Intl.NumberFormat.prototype.formatToParts";
  HandleScope handle_scope(isolate);
  CHECK_RECEIVER(JSObject, number_format_holder, method);

  Handle<Symbol> marker = isolate->factory()->intl_initialized_marker_symbol();
  Handle<Object> tag =
      JSReceiver::GetDataProperty(number_format_holder, marker);
  Handle<String> expected_tag =
      isolate->factory()->NewStringFromStaticChars("numberformat");
  if (!(tag->IsString() && String::cast(*tag)->Equals(*expected_tag))) {
    THROW_NEW_ERROR_RETURN_FAILURE(
        isolate,
        NewTypeError(MessageTemplate::kIncompatibleMethodReceiver,
                     isolate->factory()->NewStringFromAsciiChecked(method),
                     number_format_holder));
  }

  Handle<Object> x;
  if (args.length() >= 2) {
    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, x,
                                       Object::ToNumber(args.at(1)));
  } else {
    x = isolate->factory()->nan_value();
  }

  icu::DecimalFormat* number_format =
      NumberFormat::UnpackNumberFormat(isolate, number_format_holder);
  CHECK_NOT_NULL(number_format);

  Object* result = FormatNumberToParts(isolate, number_format, x->Number());
  return result;
}

}  // namespace internal
}  // namespace v8