//===- RemarkParser.cpp --------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file provides utility methods used by clients that want to use the
// parser for remark diagnostics in LLVM.
//
//===----------------------------------------------------------------------===//

#include "llvm/Remarks/RemarkParser.h"
#include "BitstreamRemarkParser.h"
#include "YAMLRemarkParser.h"
#include "llvm-c/Remarks.h"
#include "llvm/Support/CBindingWrapping.h"
#include <optional>

using namespace llvm;
using namespace llvm::remarks;

char EndOfFileError::ID = 0;

ParsedStringTable::ParsedStringTable(StringRef InBuffer) : Buffer(InBuffer) {
  while (!InBuffer.empty()) {
    // Strings are separated by '\0' bytes.
    std::pair<StringRef, StringRef> Split = InBuffer.split('\0');
    // We only store the offset from the beginning of the buffer.
    Offsets.push_back(Split.first.data() - Buffer.data());
    InBuffer = Split.second;
  }
}

Expected<StringRef> ParsedStringTable::operator[](size_t Index) const {
  if (Index >= Offsets.size())
    return createStringError(
        std::make_error_code(std::errc::invalid_argument),
        "String with index %u is out of bounds (size = %u).", Index,
        Offsets.size());

  size_t Offset = Offsets[Index];
  // If it's the last offset, we can't use the next offset to know the size of
  // the string.
  size_t NextOffset =
      (Index == Offsets.size() - 1) ? Buffer.size() : Offsets[Index + 1];
  return StringRef(Buffer.data() + Offset, NextOffset - Offset - 1);
}

Expected<std::unique_ptr<RemarkParser>>
llvm::remarks::createRemarkParser(Format ParserFormat, StringRef Buf) {
  switch (ParserFormat) {
  case Format::YAML:
    return std::make_unique<YAMLRemarkParser>(Buf);
  case Format::YAMLStrTab:
    return createStringError(
        std::make_error_code(std::errc::invalid_argument),
        "The YAML with string table format requires a parsed string table.");
  case Format::Bitstream:
    return std::make_unique<BitstreamRemarkParser>(Buf);
  case Format::Unknown:
    return createStringError(std::make_error_code(std::errc::invalid_argument),
                             "Unknown remark parser format.");
  }
  llvm_unreachable("unhandled ParseFormat");
}

Expected<std::unique_ptr<RemarkParser>>
llvm::remarks::createRemarkParser(Format ParserFormat, StringRef Buf,
                                  ParsedStringTable StrTab) {
  switch (ParserFormat) {
  case Format::YAML:
    return createStringError(std::make_error_code(std::errc::invalid_argument),
                             "The YAML format can't be used with a string "
                             "table. Use yaml-strtab instead.");
  case Format::YAMLStrTab:
    return std::make_unique<YAMLStrTabRemarkParser>(Buf, std::move(StrTab));
  case Format::Bitstream:
    return std::make_unique<BitstreamRemarkParser>(Buf, std::move(StrTab));
  case Format::Unknown:
    return createStringError(std::make_error_code(std::errc::invalid_argument),
                             "Unknown remark parser format.");
  }
  llvm_unreachable("unhandled ParseFormat");
}

Expected<std::unique_ptr<RemarkParser>>
llvm::remarks::createRemarkParserFromMeta(
    Format ParserFormat, StringRef Buf, std::optional<ParsedStringTable> StrTab,
    std::optional<StringRef> ExternalFilePrependPath) {
  switch (ParserFormat) {
  // Depending on the metadata, the format can be either yaml or yaml-strtab,
  // regardless of the input argument.
  case Format::YAML:
  case Format::YAMLStrTab:
    return createYAMLParserFromMeta(Buf, std::move(StrTab),
                                    std::move(ExternalFilePrependPath));
  case Format::Bitstream:
    return createBitstreamParserFromMeta(Buf, std::move(StrTab),
                                         std::move(ExternalFilePrependPath));
  case Format::Unknown:
    return createStringError(std::make_error_code(std::errc::invalid_argument),
                             "Unknown remark parser format.");
  }
  llvm_unreachable("unhandled ParseFormat");
}

namespace {
// Wrapper that holds the state needed to interact with the C API.
struct CParser {
  std::unique_ptr<RemarkParser> TheParser;
  std::optional<std::string> Err;

  CParser(Format ParserFormat, StringRef Buf,
          std::optional<ParsedStringTable> StrTab = std::nullopt)
      : TheParser(cantFail(
            StrTab ? createRemarkParser(ParserFormat, Buf, std::move(*StrTab))
                   : createRemarkParser(ParserFormat, Buf))) {}

  void handleError(Error E) { Err.emplace(toString(std::move(E))); }
  bool hasError() const { return Err.has_value(); }
  const char *getMessage() const { return Err ? Err->c_str() : nullptr; };
};
} // namespace

// Create wrappers for C Binding types (see CBindingWrapping.h).
DEFINE_SIMPLE_CONVERSION_FUNCTIONS(CParser, LLVMRemarkParserRef)

extern "C" LLVMRemarkParserRef LLVMRemarkParserCreateYAML(const void *Buf,
                                                          uint64_t Size) {
  return wrap(new CParser(Format::YAML,
                          StringRef(static_cast<const char *>(Buf), Size)));
}

extern "C" LLVMRemarkParserRef LLVMRemarkParserCreateBitstream(const void *Buf,
                                                               uint64_t Size) {
  return wrap(new CParser(Format::Bitstream,
                          StringRef(static_cast<const char *>(Buf), Size)));
}

extern "C" LLVMRemarkEntryRef
LLVMRemarkParserGetNext(LLVMRemarkParserRef Parser) {
  CParser &TheCParser = *unwrap(Parser);
  remarks::RemarkParser &TheParser = *TheCParser.TheParser;

  Expected<std::unique_ptr<Remark>> MaybeRemark = TheParser.next();
  if (Error E = MaybeRemark.takeError()) {
    if (E.isA<EndOfFileError>()) {
      consumeError(std::move(E));
      return nullptr;
    }

    // Handle the error. Allow it to be checked through HasError and
    // GetErrorMessage.
    TheCParser.handleError(std::move(E));
    return nullptr;
  }

  // Valid remark.
  return wrap(MaybeRemark->release());
}

extern "C" LLVMBool LLVMRemarkParserHasError(LLVMRemarkParserRef Parser) {
  return unwrap(Parser)->hasError();
}

extern "C" const char *
LLVMRemarkParserGetErrorMessage(LLVMRemarkParserRef Parser) {
  return unwrap(Parser)->getMessage();
}

extern "C" void LLVMRemarkParserDispose(LLVMRemarkParserRef Parser) {
  delete unwrap(Parser);
}