//===--- DurationRewriter.h - clang-tidy ------------------------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ABSEIL_DURATIONREWRITER_H
#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ABSEIL_DURATIONREWRITER_H

#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
#include <cinttypes>
#include <optional>

namespace clang::tidy::abseil {

/// Duration factory and conversion scales
enum class DurationScale : std::uint8_t {
  Hours = 0,
  Minutes,
  Seconds,
  Milliseconds,
  Microseconds,
  Nanoseconds,
};

/// Given a `Scale`, return the appropriate factory function call for
/// constructing a `Duration` for that scale.
llvm::StringRef getDurationFactoryForScale(DurationScale Scale);

/// Given a 'Scale', return the appropriate factory function call for
/// constructing a `Time` for that scale.
llvm::StringRef getTimeFactoryForScale(DurationScale Scale);

// Determine if `Node` represents a literal floating point or integral zero.
bool isLiteralZero(const ast_matchers::MatchFinder::MatchResult &Result,
                   const Expr &Node);

/// Possibly strip a floating point cast expression.
///
/// If `Node` represents an explicit cast to a floating point type, return
/// the textual context of the cast argument, otherwise `std::nullopt`.
std::optional<std::string>
stripFloatCast(const ast_matchers::MatchFinder::MatchResult &Result,
               const Expr &Node);

/// Possibly remove the fractional part of a floating point literal.
///
/// If `Node` represents a floating point literal with a zero fractional part,
/// return the textual context of the integral part, otherwise `std::nullopt`.
std::optional<std::string>
stripFloatLiteralFraction(const ast_matchers::MatchFinder::MatchResult &Result,
                          const Expr &Node);

/// Possibly further simplify a duration factory function's argument, without
/// changing the scale of the factory function. Return that simplification or
/// the text of the argument if no simplification is possible.
std::string
simplifyDurationFactoryArg(const ast_matchers::MatchFinder::MatchResult &Result,
                           const Expr &Node);

/// Given the name of an inverse Duration function (e.g., `ToDoubleSeconds`),
/// return its `DurationScale`, or `std::nullopt` if a match is not found.
std::optional<DurationScale> getScaleForDurationInverse(llvm::StringRef Name);

/// Given the name of an inverse Time function (e.g., `ToUnixSeconds`),
/// return its `DurationScale`, or `std::nullopt` if a match is not found.
std::optional<DurationScale> getScaleForTimeInverse(llvm::StringRef Name);

/// Given a `Scale` return the fully qualified inverse functions for it.
/// The first returned value is the inverse for `double`, and the second
/// returned value is the inverse for `int64`.
const std::pair<llvm::StringRef, llvm::StringRef> &
getDurationInverseForScale(DurationScale Scale);

/// Returns the Time inverse function name for a given `Scale`.
llvm::StringRef getTimeInverseForScale(DurationScale Scale);

/// Assuming `Node` has type `double` or `int` representing a time interval of
/// `Scale`, return the expression to make it a suitable `Duration`.
std::string rewriteExprFromNumberToDuration(
    const ast_matchers::MatchFinder::MatchResult &Result, DurationScale Scale,
    const Expr *Node);

/// Assuming `Node` has a type `int` representing a time instant of `Scale`
/// since The Epoch, return the expression to make it a suitable `Time`.
std::string rewriteExprFromNumberToTime(
    const ast_matchers::MatchFinder::MatchResult &Result, DurationScale Scale,
    const Expr *Node);

/// Return `false` if `E` is a either: not a macro at all; or an argument to
/// one.  In the both cases, we often want to do the transformation.
bool isInMacro(const ast_matchers::MatchFinder::MatchResult &Result,
               const Expr *E);

AST_MATCHER_FUNCTION(ast_matchers::internal::Matcher<FunctionDecl>,
                     DurationConversionFunction) {
  using namespace clang::ast_matchers;
  return functionDecl(
      hasAnyName("::absl::ToDoubleHours", "::absl::ToDoubleMinutes",
                 "::absl::ToDoubleSeconds", "::absl::ToDoubleMilliseconds",
                 "::absl::ToDoubleMicroseconds", "::absl::ToDoubleNanoseconds",
                 "::absl::ToInt64Hours", "::absl::ToInt64Minutes",
                 "::absl::ToInt64Seconds", "::absl::ToInt64Milliseconds",
                 "::absl::ToInt64Microseconds", "::absl::ToInt64Nanoseconds"));
}

AST_MATCHER_FUNCTION(ast_matchers::internal::Matcher<FunctionDecl>,
                     DurationFactoryFunction) {
  using namespace clang::ast_matchers;
  return functionDecl(hasAnyName("::absl::Nanoseconds", "::absl::Microseconds",
                                 "::absl::Milliseconds", "::absl::Seconds",
                                 "::absl::Minutes", "::absl::Hours"));
}

AST_MATCHER_FUNCTION(ast_matchers::internal::Matcher<FunctionDecl>,
                     TimeConversionFunction) {
  using namespace clang::ast_matchers;
  return functionDecl(hasAnyName(
      "::absl::ToUnixHours", "::absl::ToUnixMinutes", "::absl::ToUnixSeconds",
      "::absl::ToUnixMillis", "::absl::ToUnixMicros", "::absl::ToUnixNanos"));
}

AST_MATCHER_FUNCTION_P(ast_matchers::internal::Matcher<Stmt>,
                       comparisonOperatorWithCallee,
                       ast_matchers::internal::Matcher<Decl>, funcDecl) {
  using namespace clang::ast_matchers;
  return binaryOperator(
      anyOf(hasOperatorName(">"), hasOperatorName(">="), hasOperatorName("=="),
            hasOperatorName("<="), hasOperatorName("<")),
      hasEitherOperand(ignoringImpCasts(callExpr(callee(funcDecl)))));
}

} // namespace clang::tidy::abseil

#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ABSEIL_DURATIONREWRITER_H
