/*
 * Copyright 2020 WebAssembly Community Group participants
 *
 * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// wasm-split: Split a module in two or instrument a module to inform future
// splitting.

#include "ir/module-splitting.h"
#include "ir/module-utils.h"
#include "support/name.h"
#include "support/utilities.h"
#include "tool-options.h"
#include "wasm-io.h"
#include "wasm-validator.h"
#include <sstream>

using namespace wasm;

namespace {

const std::string DEFAULT_PROFILE_EXPORT("__write_profile");

std::set<Name> parseNameList(const std::string& list) {
  std::set<Name> names;
  std::istringstream stream(list);
  for (std::string name; std::getline(stream, name, ',');) {
    names.insert(name);
  }
  return names;
}

struct WasmSplitOptions : ToolOptions {
  bool verbose = false;

  bool instrument = false;

  std::string profileFile;
  std::string profileExport = DEFAULT_PROFILE_EXPORT;

  std::set<Name> keepFuncs;
  std::set<Name> splitFuncs;

  std::string input;
  std::string output;
  std::string primaryOutput;
  std::string secondaryOutput;

  std::string importNamespace;
  std::string placeholderNamespace;
  std::string exportPrefix;

  WasmSplitOptions();
  bool validate();
  void parse(int argc, const char* argv[]);
};

WasmSplitOptions::WasmSplitOptions()
  : ToolOptions("wasm-split",
                "Split a module into a primary module and a secondary "
                "module or instrument a module to gather a profile that "
                "can inform future splitting.") {
  (*this)
    .add("--instrument",
         "",
         "Instrument the module to generate a profile that can be used to "
         "guide splitting",
         Options::Arguments::Zero,
         [&](Options* o, const std::string& argument) { instrument = true; })
    .add(
      "--profile",
      "",
      "The profile to use to guide splitting. May not be used with "
      "--instrument.",
      Options::Arguments::One,
      [&](Options* o, const std::string& argument) { profileFile = argument; })
    .add("--profile-export",
         "",
         "The export name of the function the embedder calls to write the "
         "profile into memory. Defaults to `__write_profile`. Must be used "
         "with --instrument.",
         Options::Arguments::One,
         [&](Options* o, const std::string& argument) {
           profileExport = argument;
         })
    .add("--keep-funcs",
         "",
         "Comma-separated list of functions to keep in the primary module, "
         "regardless of any profile.",
         Options::Arguments::One,
         [&](Options* o, const std::string& argument) {
           keepFuncs = parseNameList(argument);
         })
    .add("--split-funcs",
         "",
         "Comma-separated list of functions to split into the secondary "
         "module, regardless of any profile. If there is no profile, then "
         "this defaults to all functions defined in the module.",
         Options::Arguments::One,
         [&](Options* o, const std::string& argument) {
           splitFuncs = parseNameList(argument);
         })
    .add("--output",
         "-o",
         "Output file. Only usable with --instrument.",
         Options::Arguments::One,
         [&](Options* o, const std::string& argument) { output = argument; })
    .add("--primary-output",
         "-o1",
         "Output file for the primary module. Not usable with --instrument.",
         Options::Arguments::One,
         [&](Options* o, const std::string& argument) {
           primaryOutput = argument;
         })
    .add("--secondary-output",
         "-o2",
         "Output file for the secondary module. Not usable with --instrument.",
         Options::Arguments::One,
         [&](Options* o, const std::string& argument) {
           secondaryOutput = argument;
         })
    .add("--import-namespace",
         "",
         "The namespace from which to import objects from the primary "
         "module into the secondary module.",
         Options::Arguments::One,
         [&](Options* o, const std::string& argument) {
           importNamespace = argument;
         })
    .add("--placeholder-namespace",
         "",
         "The namespace from which to import placeholder functions into "
         "the primary module.",
         Options::Arguments::One,
         [&](Options* o, const std::string& argument) {
           placeholderNamespace = argument;
         })
    .add(
      "--export-prefix",
      "",
      "An identifying prefix to prepend to new export names created "
      "by module splitting.",
      Options::Arguments::One,
      [&](Options* o, const std::string& argument) { exportPrefix = argument; })
    .add("--verbose",
         "-v",
         "Verbose output mode. Prints the functions that will be kept "
         "and split out when splitting a module.",
         Options::Arguments::Zero,
         [&](Options* o, const std::string& argument) {
           verbose = true;
           quiet = false;
         })
    .add_positional(
      "INFILE",
      Options::Arguments::One,
      [&](Options* o, const std::string& argument) { input = argument; });
}

bool WasmSplitOptions::validate() {
  bool valid = true;
  auto fail = [&](auto msg) {
    std::cerr << "error: " << msg << "\n";
    valid = false;
  };

  if (!input.size()) {
    fail("no input file");
  }
  if (instrument) {
    using Opt = std::pair<const std::string&, const std::string>;
    for (auto& opt : {Opt{profileFile, "--profile"},
                      Opt{primaryOutput, "primary output"},
                      Opt{secondaryOutput, "secondary output"},
                      Opt{importNamespace, "--import-namespace"},
                      Opt{placeholderNamespace, "--placeholder-namespace"},
                      Opt{exportPrefix, "--export-prefix"}}) {
      if (opt.first.size()) {
        fail(opt.second + " cannot be used with --instrument");
      }
    }
    if (keepFuncs.size()) {
      fail("--keep-funcs cannot be used with --instrument");
    }
    if (splitFuncs.size()) {
      fail("--split-funcs cannot be used with --instrument");
    }
  } else {
    if (output.size()) {
      fail(
        "must provide separate primary and secondary output with -o1 and -o2");
    }
    if (profileExport != DEFAULT_PROFILE_EXPORT) {
      fail("--profile-export must be used with --instrument");
    }
  }

  std::vector<Name> impossible;
  std::set_intersection(keepFuncs.begin(),
                        keepFuncs.end(),
                        splitFuncs.begin(),
                        splitFuncs.end(),
                        std::inserter(impossible, impossible.end()));
  for (auto& func : impossible) {
    fail(std::string("Cannot both keep and split out function ") +
         func.c_str());
  }

  return valid;
}

void WasmSplitOptions::parse(int argc, const char* argv[]) {
  ToolOptions::parse(argc, argv);
  // Since --quiet is defined in ToolOptions but --verbose is defined here,
  // --quiet doesn't know to unset --verbose. Fix it up here.
  if (quiet && verbose) {
    verbose = false;
  }
}

void parseInput(Module& wasm, const WasmSplitOptions& options) {
  ModuleReader reader;
  reader.setProfile(options.profile);
  try {
    reader.read(options.input, wasm);
  } catch (ParseException& p) {
    p.dump(std::cerr);
    std::cerr << '\n';
    Fatal() << "error parsing wasm";
  } catch (std::bad_alloc&) {
    Fatal() << "error building module, std::bad_alloc (possibly invalid "
               "request for silly amounts of memory)";
  }
  options.applyFeatures(wasm);
}

void instrumentModule(Module& wasm, const WasmSplitOptions& options) {
  Fatal() << "TODO: implement instrumentation\n";
}

void splitModule(Module& wasm, const WasmSplitOptions& options) {
  std::set<Name> keepFuncs;

  if (options.profileFile.size()) {
    // Use the profile to initialize `keepFuncs`
    Fatal() << "TODO: implement reading profiles\n";
  }

  // Add in the functions specified with --keep-funcs
  for (auto& func : options.keepFuncs) {
    if (!options.quiet && wasm.getFunctionOrNull(func) == nullptr) {
      std::cerr << "warning: function " << func << " does not exist\n";
    }
    keepFuncs.insert(func);
  }

  // Remove the functions specified with --remove-funcs
  for (auto& func : options.splitFuncs) {
    auto* function = wasm.getFunctionOrNull(func);
    if (!options.quiet && function == nullptr) {
      std::cerr << "warning: function " << func << " does not exist\n";
    }
    if (function && function->imported()) {
      if (!options.quiet) {
        std::cerr << "warning: cannot split out imported function " << func
                  << "\n";
      }
    } else {
      keepFuncs.erase(func);
    }
  }

  if (!options.quiet && keepFuncs.size() == 0) {
    std::cerr << "warning: not keeping any functions in the primary module\n";
  }

  // If warnings are enabled, check that any functions are being split out.
  if (!options.quiet) {
    std::set<Name> splitFuncs;
    ModuleUtils::iterDefinedFunctions(wasm, [&](Function* func) {
      if (keepFuncs.count(func->name) == 0) {
        splitFuncs.insert(func->name);
      }
    });

    if (splitFuncs.size() == 0) {
      std::cerr
        << "warning: not splitting any functions out to the secondary module\n";
    }

    // Dump the kept and split functions if we are verbose
    if (options.verbose) {
      auto printCommaSeparated = [&](auto funcs) {
        for (auto it = funcs.begin(); it != funcs.end(); ++it) {
          if (it != funcs.begin()) {
            std::cout << ", ";
          }
          std::cout << *it;
        }
      };

      std::cout << "Keeping functions: ";
      printCommaSeparated(keepFuncs);
      std::cout << "\n";

      std::cout << "Splitting out functions: ";
      printCommaSeparated(splitFuncs);
      std::cout << "\n";
    }
  }

  // Actually perform the splitting
  ModuleSplitting::Config config;
  config.primaryFuncs = std::move(keepFuncs);
  if (options.importNamespace.size()) {
    config.importNamespace = options.importNamespace;
  }
  if (options.placeholderNamespace.size()) {
    config.placeholderNamespace = options.placeholderNamespace;
  }
  if (options.exportPrefix.size()) {
    config.newExportPrefix = options.exportPrefix;
  }
  std::unique_ptr<Module> secondary =
    ModuleSplitting::splitFunctions(wasm, config);

  // Write the output modules
  ModuleWriter writer;
  writer.setBinary(true);
  writer.write(wasm, options.primaryOutput);
  writer.write(*secondary, options.secondaryOutput);
}

} // anonymous namespace

int main(int argc, const char* argv[]) {
  WasmSplitOptions options;
  options.parse(argc, argv);

  if (!options.validate()) {
    Fatal() << "Invalid command line arguments";
  }

  Module wasm;
  parseInput(wasm, options);

  if (options.passOptions.validate && !WasmValidator().validate(wasm)) {
    Fatal() << "error validating input";
  }

  if (options.instrument) {
    instrumentModule(wasm, options);
  } else {
    splitModule(wasm, options);
  }
}