// Copyright 2021 The IREE Authors
//
// Licensed 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

#include "iree/compiler/API/MLIRInterop.h"
#include "mlir/Bindings/Python/PybindAdaptors.h"

namespace py = pybind11;

namespace {

struct PyCompilerOptions {
  PyCompilerOptions() : options(ireeCompilerOptionsCreate()) {}
  PyCompilerOptions(const PyCompilerOptions &) = delete;
  void operator=(const PyCompilerOptions &) = delete;
  PyCompilerOptions(PyCompilerOptions &&other) : options(other.options) {
    other.options = {nullptr};
  }
  ~PyCompilerOptions() {
    if (options.ptr) ireeCompilerOptionsDestroy(options);
  }
  IreeCompilerOptions options;
};

/// Accumulates int a python file-like object, either writing text (default)
/// or binary.
class PyFileAccumulator {
 public:
  PyFileAccumulator(pybind11::object fileObject, bool binary)
      : pyWriteFunction(fileObject.attr("write")), binary(binary) {}

  void *getUserData() { return this; }

  MlirStringCallback getCallback() {
    return [](MlirStringRef part, void *userData) {
      pybind11::gil_scoped_acquire();
      PyFileAccumulator *accum = static_cast<PyFileAccumulator *>(userData);
      if (accum->binary) {
        // Note: Still has to copy and not avoidable with this API.
        pybind11::bytes pyBytes(part.data, part.length);
        accum->pyWriteFunction(pyBytes);
      } else {
        pybind11::str pyStr(part.data,
                            part.length);  // Decodes as UTF-8 by default.
        accum->pyWriteFunction(pyStr);
      }
    };
  }

 private:
  pybind11::object pyWriteFunction;
  bool binary;
};

void setOptionsFromArgs(IreeCompilerOptions &options, py::args &args) {
  std::vector<std::string> allocedArgs;
  std::vector<const char *> cArgs;
  for (auto &argObject : args) {
    allocedArgs.push_back(py::cast<std::string>(argObject));
  }
  // Can only get c_str() after finished mutating the vector.
  for (auto &argStr : allocedArgs) {
    cArgs.push_back(argStr.c_str());
  }

  std::string errorMessage;
  auto callback = +[](MlirStringRef msg, void *userData) {
    std::string *innerErrorMessage = static_cast<std::string *>(userData);
    if (!innerErrorMessage->empty()) innerErrorMessage->append("\n");
    innerErrorMessage->append(msg.data, msg.length);
  };
  if (mlirLogicalResultIsFailure(ireeCompilerOptionsSetFlags(
          options, cArgs.size(), cArgs.data(), callback,
          static_cast<void *>(&errorMessage)))) {
    throw std::invalid_argument(std::move(errorMessage));
  }
}

py::list getFlagsFromOptions(IreeCompilerOptions &options,
                             bool nonDefaultOnly) {
  py::list flags;
  auto callback = +[](MlirStringRef flag, void *userData) {
    py::list *innerFlags = static_cast<py::list *>(userData);
    py::str s(flag.data, flag.length);
    innerFlags->append(std::move(s));
  };
  ireeCompilerOptionsGetFlags(options, nonDefaultOnly, callback,
                              static_cast<void *>(&flags));
  return flags;
}

}  // namespace

static const char BUILD_IREE_VM_PASS_PIPELINE_DOCSTRING[] =
    R"(Populates VM compilation pass on a PassManager.

This is the primary interface to IREE's backend compiler, providing compilation
from a supported set of input dialects to the `vm` dialect, representing
IREE's lowest level representation.
)";

static const char TRANSLATE_MODULE_TO_VM_BYTECODE_DOCSTRING[] =
    R"(Given a `vm.module` translate it to VM bytecode.

The provided `file` argument must be a valid `IO` object, capable of having
binary data written to it.
)";

PYBIND11_MODULE(_ireecTransforms, m) {
  m.doc() = "ireec transforms API";
  ireeCompilerRegisterTargetBackends();

  m.def("register_all_dialects",
        [](MlirContext context) { ireeCompilerRegisterAllDialects(context); });

  py::class_<PyCompilerOptions>(m, "CompilerOptions",
                                "Options for the IREE backend compiler.")
      .def(py::init([](py::args args) {
        PyCompilerOptions self;
        if (!args.empty()) {
          setOptionsFromArgs(self.options, args);
        }
        return self;
      }))
      .def(
          "set",
          [](PyCompilerOptions &self, py::args args) {
            setOptionsFromArgs(self.options, args);
          },
          "Sets options from flag values in the usual form for command line "
          "options")
      .def(
          "get",
          [](PyCompilerOptions &self, bool nonDefaultOnly) {
            return getFlagsFromOptions(self.options, nonDefaultOnly);
          },
          py::arg("non_default_only") = true,
          "Gets a list of flag values for the options (by default only those "
          "that have changed).")
      .def("__repr__", [](PyCompilerOptions &self) {
        py::list flags =
            getFlagsFromOptions(self.options, /*nonDefaultOnly=*/true);
        return py::str("<CompilerOptions:") + py::repr(flags) + py::str(">");
      });
  m.def(
      "build_iree_vm_pass_pipeline",
      [](PyCompilerOptions &options, MlirPassManager passManager) {
        MlirOpPassManager opPassManager =
            mlirPassManagerGetAsOpPassManager(passManager);
        ireeCompilerBuildIREEVMPassPipeline(options.options, opPassManager);
      },
      py::arg("options"), py::arg("pass_manager"),
      BUILD_IREE_VM_PASS_PIPELINE_DOCSTRING);

  m.def(
      "translate_module_to_vm_bytecode",
      [](PyCompilerOptions &options, MlirModule module, py::object file) {
        PyFileAccumulator accum(file, /*binary=*/true);
        MlirOperation operation = mlirModuleGetOperation(module);
        auto result = ireeCompilerTranslateModuletoVMBytecode(
            options.options, operation, accum.getCallback(),
            accum.getUserData());
        if (mlirLogicalResultIsFailure(result)) {
          throw std::runtime_error("failure translating module to bytecode");
        }
      },
      py::arg("options"), py::arg("module"), py::arg("file"),
      TRANSLATE_MODULE_TO_VM_BYTECODE_DOCSTRING);
}