/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * 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.
 */

#include "AST.h"
#include "Coordinator.h"
#include "FQName.h"
#include "Scope.h"

#include <hidl-util/Formatter.h>
#include <android-base/logging.h>
#include <set>
#include <stdio.h>
#include <string>
#include <unistd.h>
#include <vector>

using namespace android;

struct OutputHandler {
    std::string mKey;
    enum OutputMode {
        NEEDS_DIR,
        NEEDS_FILE,
        NOT_NEEDED
    } mOutputMode;

    enum ValRes {
        FAILED,
        PASS_PACKAGE,
        PASS_FULL
    };
    ValRes (*validate)(const FQName &, const std::string &language);
    status_t (*generate)(const FQName &fqName,
                         const char *hidl_gen,
                         Coordinator *coordinator,
                         const std::string &outputDir);
};

static status_t generateSourcesForFile(
        const FQName &fqName,
        const char *,
        Coordinator *coordinator,
        const std::string &outputDir,
        const std::string &lang) {
    CHECK(fqName.isFullyQualified());

    AST *ast;
    std::string limitToType;

    if (fqName.name().find("types.") == 0) {
        CHECK(lang == "java");  // Already verified in validate().

        limitToType = fqName.name().substr(strlen("types."));

        FQName typesName(fqName.package(), fqName.version(), "types");
        ast = coordinator->parse(typesName);
    } else {
        ast = coordinator->parse(fqName);
    }

    if (ast == NULL) {
        fprintf(stderr,
                "ERROR: Could not parse %s. Aborting.\n",
                fqName.string().c_str());

        return UNKNOWN_ERROR;
    }

    if (lang == "c++") {
        return ast->generateCpp(outputDir);
    }
    if (lang == "c++-impl") {
        return ast->generateCppImpl(outputDir);
    }
    if (lang == "java") {
        return ast->generateJava(outputDir, limitToType);
    }
    if (lang == "vts") {
        return ast->generateVts(outputDir);
    }
    // Unknown language.
    return UNKNOWN_ERROR;
}

static status_t generateSourcesForPackage(
        const FQName &packageFQName,
        const char *hidl_gen,
        Coordinator *coordinator,
        const std::string &outputDir,
        const std::string &lang) {
    CHECK(packageFQName.isValid() &&
        !packageFQName.isFullyQualified() &&
        packageFQName.name().empty());

    std::vector<FQName> packageInterfaces;

    status_t err =
        coordinator->appendPackageInterfacesToVector(packageFQName,
                                                     &packageInterfaces);

    if (err != OK) {
        return err;
    }

    for (const auto &fqName : packageInterfaces) {
        err = generateSourcesForFile(
                fqName, hidl_gen, coordinator, outputDir, lang);
        if (err != OK) {
            return err;
        }
    }

    return OK;
}

static std::string makeLibraryName(const FQName &packageFQName) {
    return packageFQName.string();
}

static void generateMakefileSectionForType(
        Formatter &out,
        Coordinator *coordinator,
        const FQName &packageFQName,
        const FQName &fqName,
        const char *typeName) {
    out << "\n"
        << "\n#"
        << "\n# Build " << fqName.name() << ".hal";

    if (typeName != nullptr) {
        out << " (" << typeName << ")";
    }

    out << "\n#"
        << "\nGEN := $(intermediates)/"
        << coordinator->convertPackageRootToPath(packageFQName)
        << coordinator->getPackagePath(packageFQName, true /* relative */);
    if (typeName == nullptr) {
        out << fqName.name() << ".java";
    } else {
        out << typeName << ".java";
    }

    out << "\n$(GEN): $(HIDL)";
    out << "\n$(GEN): PRIVATE_HIDL := $(HIDL)";
    out << "\n$(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/"
        << fqName.name() << ".hal";

    {
        AST *ast = coordinator->parse(fqName);
        CHECK(ast != nullptr);
        const std::set<FQName>& refs = ast->getImportedNames();
        for (auto depFQName : refs) {
            // If the package of depFQName is the same as this fqName's package,
            // then add it explicitly as a .hal dependency within the same
            // package.
            if (fqName.package() == depFQName.package() &&
                fqName.version() == depFQName.version()) {
                    // PRIVATE_DEPS is not actually being used in the
                    // auto-generated file, but is necessary if the build rule
                    // ever needs to use the dependency information, since the
                    // built-in Make variables are not supported in the Android
                    // build system.
                    out << "\n$(GEN): PRIVATE_DEPS += $(LOCAL_PATH)/"
                        << depFQName.name() << ".hal";
                    // This is the actual dependency.
                    out << "\n$(GEN): $(LOCAL_PATH)/"
                        << depFQName.name() << ".hal";
            }
        }
    }

    out << "\n$(GEN): PRIVATE_OUTPUT_DIR := $(intermediates)"
        << "\n$(GEN): PRIVATE_CUSTOM_TOOL = \\";
    out.indent();
    out.indent();
    out << "\n$(PRIVATE_HIDL) -o $(PRIVATE_OUTPUT_DIR) \\"
        << "\n-Ljava"
        << " -r"
        << coordinator->getPackageRoot(packageFQName) << ":"
        << coordinator->getPackageRootPath(packageFQName) << " \\\n";

    out << packageFQName.string()
        << "::"
        << fqName.name();

    if (typeName != nullptr) {
        out << "." << typeName;
    }

    out << "\n";

    out.unindent();
    out.unindent();

    out << "\n$(GEN): $(LOCAL_PATH)/" << fqName.name() << ".hal";
    out << "\n\t$(transform-generated-source)";
    out << "\nLOCAL_GENERATED_SOURCES += $(GEN)";
}

static void generateMakefileSection(
        Formatter &out,
        Coordinator *coordinator,
        const FQName &packageFQName,
        const std::vector<FQName> &packageInterfaces,
        AST *typesAST) {
    for (const auto &fqName : packageInterfaces) {
        if (fqName.name() == "types") {
            CHECK(typesAST != nullptr);

            Scope *rootScope = typesAST->scope();

            std::vector<NamedType *> subTypes = rootScope->getSubTypes();
            std::sort(
                    subTypes.begin(),
                    subTypes.end(),
                    [](const NamedType *a, const NamedType *b) -> bool {
                        return a->fqName() < b->fqName();
                    });

            for (const auto &type : subTypes) {
                if (type->isTypeDef()) {
                    continue;
                }

                generateMakefileSectionForType(
                        out,
                        coordinator,
                        packageFQName,
                        fqName,
                        type->localName().c_str());
            }

            continue;
        }

        generateMakefileSectionForType(
                out,
                coordinator,
                packageFQName,
                fqName,
                nullptr /* typeName */);
    }
}

static status_t isPackageJavaCompatible(
        const FQName &packageFQName,
        Coordinator *coordinator,
        bool *compatible) {
    std::vector<FQName> todo;
    status_t err =
        coordinator->appendPackageInterfacesToVector(packageFQName, &todo);

    if (err != OK) {
        return err;
    }

    std::set<FQName> seen;
    for (const auto &iface : todo) {
        seen.insert(iface);
    }

    // Form the transitive closure of all imported interfaces (and types.hal-s)
    // If any one of them is not java compatible, this package isn't either.
    while (!todo.empty()) {
        const FQName fqName = todo.back();
        todo.pop_back();

        AST *ast = coordinator->parse(fqName);

        if (ast == nullptr) {
            return UNKNOWN_ERROR;
        }

        if (!ast->isJavaCompatible()) {
            *compatible = false;
            return OK;
        }

        std::set<FQName> importedPackages;
        ast->getImportedPackages(&importedPackages);

        for (const auto &package : importedPackages) {
            std::vector<FQName> packageInterfaces;
            status_t err = coordinator->appendPackageInterfacesToVector(
                    package, &packageInterfaces);

            if (err != OK) {
                return err;
            }

            for (const auto &iface : packageInterfaces) {
                if (seen.find(iface) != seen.end()) {
                    continue;
                }

                todo.push_back(iface);
                seen.insert(iface);
            }
        }
    }

    *compatible = true;
    return OK;
}

static bool packageNeedsJavaCode(
        const std::vector<FQName> &packageInterfaces, AST *typesAST) {
    // If there is more than just a types.hal file to this package we'll
    // definitely need to generate Java code.
    if (packageInterfaces.size() > 1
            || packageInterfaces[0].name() != "types") {
        return true;
    }

    CHECK(typesAST != nullptr);

    // We'll have to generate Java code if types.hal contains any non-typedef
    // type declarations.

    Scope *rootScope = typesAST->scope();
    std::vector<NamedType *> subTypes = rootScope->getSubTypes();

    for (const auto &subType : subTypes) {
        if (!subType->isTypeDef()) {
            return true;
        }
    }

    return false;
}

static void generateMakefileSectionForJavaConstants(
        Formatter &out,
        Coordinator *coordinator,
        const FQName &packageFQName,
        const std::vector<FQName> &packageInterfaces) {
    out << "\n#"
        << "\nGEN := $(intermediates)/"
        << coordinator->convertPackageRootToPath(packageFQName)
        << coordinator->getPackagePath(packageFQName, true /* relative */)
        << "Constants.java";

    out << "\n$(GEN): $(HIDL)\n";
    for (const auto &iface : packageInterfaces) {
        out << "$(GEN): $(LOCAL_PATH)/" << iface.name() << ".hal\n";
    }
    out << "\n$(GEN): PRIVATE_HIDL := $(HIDL)";
    out << "\n$(GEN): PRIVATE_OUTPUT_DIR := $(intermediates)"
        << "\n$(GEN): PRIVATE_CUSTOM_TOOL = \\";
    out.indent();
    out.indent();
    out << "\n$(PRIVATE_HIDL) -o $(PRIVATE_OUTPUT_DIR) \\"
        << "\n-Ljava-constants"
        << " -r"
        << coordinator->getPackageRoot(packageFQName) << ":"
        << coordinator->getPackageRootPath(packageFQName) << " \\\n";

    out << packageFQName.string();
    out << "\n";

    out.unindent();
    out.unindent();

    out << "\n$(GEN):";
    out << "\n\t$(transform-generated-source)";
    out << "\nLOCAL_GENERATED_SOURCES += $(GEN)";
}

static status_t generateMakefileForPackage(
        const FQName &packageFQName,
        const char *hidl_gen,
        Coordinator *coordinator,
        const std::string &) {

    CHECK(packageFQName.isValid() &&
          !packageFQName.isFullyQualified() &&
          packageFQName.name().empty());

    std::vector<FQName> packageInterfaces;

    status_t err =
        coordinator->appendPackageInterfacesToVector(packageFQName,
                                                     &packageInterfaces);

    if (err != OK) {
        return err;
    }

    std::set<FQName> importedPackages;
    AST *typesAST = nullptr;
    std::vector<const Type *> exportedTypes;

    for (const auto &fqName : packageInterfaces) {
        AST *ast = coordinator->parse(fqName);

        if (ast == NULL) {
            fprintf(stderr,
                    "ERROR: Could not parse %s. Aborting.\n",
                    fqName.string().c_str());

            return UNKNOWN_ERROR;
        }

        if (fqName.name() == "types") {
            typesAST = ast;
        }

        ast->getImportedPackages(&importedPackages);
        ast->appendToExportedTypesVector(&exportedTypes);
    }

    bool packageIsJavaCompatible;
    err = isPackageJavaCompatible(
            packageFQName, coordinator, &packageIsJavaCompatible);

    if (err != OK) {
        return err;
    }

    bool haveJavaConstants = !exportedTypes.empty();

    if (!packageIsJavaCompatible && !haveJavaConstants) {
        return OK;
    }

    if (!packageNeedsJavaCode(packageInterfaces, typesAST)) {
        return OK;
    }

    std::string path =
        coordinator->getPackagePath(packageFQName, false /* relative */);

    path.append("Android.mk");

    CHECK(Coordinator::MakeParentHierarchy(path));
    FILE *file = fopen(path.c_str(), "w");

    if (file == NULL) {
        return -errno;
    }

    const std::string libraryName = makeLibraryName(packageFQName);

    Formatter out(file);

    out << "# This file is autogenerated by hidl-gen. Do not edit manually.\n\n";
    out << "LOCAL_PATH := $(call my-dir)\n";

    enum LibraryStyle {
        LIBRARY_STYLE_REGULAR,
        LIBRARY_STYLE_STATIC,
        LIBRARY_STYLE_END,
    };

    for (int style = LIBRARY_STYLE_REGULAR;
            (packageIsJavaCompatible && style != LIBRARY_STYLE_END);
            ++style) {
        const std::string staticSuffix =
            (style == LIBRARY_STYLE_STATIC) ? "-static" : "";

        out << "\n"
            << "########################################"
            << "########################################\n\n";

        out << "include $(CLEAR_VARS)\n"
            << "LOCAL_MODULE := "
            << libraryName
            << "-java"
            << staticSuffix
            << "\nLOCAL_MODULE_CLASS := JAVA_LIBRARIES\n\n"
            << "intermediates := $(local-generated-sources-dir)\n\n"
            << "HIDL := $(HOST_OUT_EXECUTABLES)/"
            << hidl_gen
            << "$(HOST_EXECUTABLE_SUFFIX)";

        if (!importedPackages.empty()) {
            out << "\n"
                << "\nLOCAL_"
                << ((style == LIBRARY_STYLE_STATIC) ? "STATIC_" : "")
                << "JAVA_LIBRARIES := \\";

            out.indent();
            for (const auto &importedPackage : importedPackages) {
                out << "\n"
                    << makeLibraryName(importedPackage)
                    << "-java"
                    << staticSuffix
                    << " \\";
            }
            out << "\n";
            out.unindent();
        }

        generateMakefileSection(
                out,
                coordinator,
                packageFQName,
                packageInterfaces,
                typesAST);

        out << "\ninclude $(BUILD_"
            << ((style == LIBRARY_STYLE_STATIC) ? "STATIC_" : "")
            << "JAVA_LIBRARY)\n\n";
    }

    if (haveJavaConstants) {
        out << "\n"
            << "########################################"
            << "########################################\n\n";

        out << "include $(CLEAR_VARS)\n"
            << "LOCAL_MODULE := "
            << libraryName
            << "-java-constants"
            << "\nLOCAL_MODULE_CLASS := JAVA_LIBRARIES\n\n"
            << "intermediates := $(local-generated-sources-dir)\n\n"
            << "HIDL := $(HOST_OUT_EXECUTABLES)/"
            << hidl_gen
            << "$(HOST_EXECUTABLE_SUFFIX)";

        generateMakefileSectionForJavaConstants(
                out, coordinator, packageFQName, packageInterfaces);

        out << "\n# Avoid dependency cycle of framework.jar -> this-library "
            << "-> framework.jar\n"
            << "LOCAL_NO_STANDARD_LIBRARIES := true\n"
            << "LOCAL_JAVA_LIBRARIES := core-oj\n\n"
            << "include $(BUILD_STATIC_JAVA_LIBRARY)\n\n";
    }

    out << "\n\n"
        << "include $(call all-makefiles-under,$(LOCAL_PATH))\n";

    return OK;
}

OutputHandler::ValRes validateForMakefile(
        const FQName &fqName, const std::string & /* language */) {
    if (fqName.package().empty()) {
        fprintf(stderr, "ERROR: Expecting package name\n");
        return OutputHandler::FAILED;
    }

    if (fqName.version().empty()) {
        fprintf(stderr, "ERROR: Expecting package version\n");
        return OutputHandler::FAILED;
    }

    if (!fqName.name().empty()) {
        fprintf(stderr,
                "ERROR: Expecting only package name and version.\n");
        return OutputHandler::FAILED;
    }

    return OutputHandler::PASS_PACKAGE;
}

static void generateAndroidBpGenSection(
        Formatter &out,
        const FQName &packageFQName,
        const char *hidl_gen,
        Coordinator *coordinator,
        const std::string &genName,
        const char *language,
        const std::vector<FQName> &packageInterfaces,
        const std::function<void(Formatter&, const FQName)> outputFn) {

    out << "genrule {\n";
    out.indent();
    out << "name: \"" << genName << "\",\n"
        << "tools: [\"" << hidl_gen << "\"],\n";

    out << "cmd: \"$(location " << hidl_gen << ") -o $(genDir)"
        << " -L" << language
        << " -r"
        << coordinator->getPackageRoot(packageFQName) << ":"
        << coordinator->getPackageRootPath(packageFQName)
        << " " << packageFQName.string() << "\",\n";

    out << "srcs: [\n";
    out.indent();
    for (const auto &fqName : packageInterfaces) {
        out << "\"" << fqName.name() << ".hal\",\n";
    }
    out.unindent();
    out << "],\n";

    out << "out: [\n";
    out.indent();
    for (const auto &fqName : packageInterfaces) {
        outputFn(out, fqName);
    }
    out.unindent();
    out << "],\n";

    out.unindent();
    out << "}\n\n";
}

static status_t generateAndroidBpForPackage(
        const FQName &packageFQName,
        const char *hidl_gen,
        Coordinator *coordinator,
        const std::string &) {

    CHECK(packageFQName.isValid() &&
          !packageFQName.isFullyQualified() &&
          packageFQName.name().empty());

    std::vector<FQName> packageInterfaces;

    status_t err =
        coordinator->appendPackageInterfacesToVector(packageFQName,
                                                     &packageInterfaces);

    if (err != OK) {
        return err;
    }

    std::set<FQName> importedPackages;
    AST *typesAST = nullptr;

    for (const auto &fqName : packageInterfaces) {
        AST *ast = coordinator->parse(fqName);

        if (ast == NULL) {
            fprintf(stderr,
                    "ERROR: Could not parse %s. Aborting.\n",
                    fqName.string().c_str());

            return UNKNOWN_ERROR;
        }

        if (fqName.name() == "types") {
            typesAST = ast;
        }

        ast->getImportedPackages(&importedPackages);
    }

    std::string path =
        coordinator->getPackagePath(packageFQName, false /* relative */);

    path.append("Android.bp");

    CHECK(Coordinator::MakeParentHierarchy(path));
    FILE *file = fopen(path.c_str(), "w");

    if (file == NULL) {
        return -errno;
    }

    const std::string libraryName = makeLibraryName(packageFQName);
    const std::string genSourceName = libraryName + "_genc++";
    const std::string genHeaderName = libraryName + "_genc++_headers";
    const std::string pathPrefix =
        coordinator->convertPackageRootToPath(packageFQName) +
        coordinator->getPackagePath(packageFQName, true /* relative */);

    Formatter out(file);

    out << "// This file is autogenerated by hidl-gen. Do not edit manually.\n\n";

    // Rule to generate the C++ source files
    generateAndroidBpGenSection(
            out,
            packageFQName,
            hidl_gen,
            coordinator,
            genSourceName,
            "c++",
            packageInterfaces,
            [&pathPrefix](Formatter &out, const FQName &fqName) {
                if (fqName.name() == "types") {
                    out << "\"" << pathPrefix << "types.cpp\",\n";
                } else {
                    out << "\"" << pathPrefix << fqName.name().substr(1) << "All.cpp\",\n";
                }
            });

    // Rule to generate the C++ header files
    generateAndroidBpGenSection(
            out,
            packageFQName,
            hidl_gen,
            coordinator,
            genHeaderName,
            "c++",
            packageInterfaces,
            [&pathPrefix](Formatter &out, const FQName &fqName) {
                out << "\"" << pathPrefix << fqName.name() << ".h\",\n";
                if (fqName.name() != "types") {
                    out << "\"" << pathPrefix << "IHw" << fqName.name().substr(1) << ".h\",\n";
                    out << "\"" << pathPrefix << "Bn" << fqName.name().substr(1) << ".h\",\n";
                    out << "\"" << pathPrefix << "Bp" << fqName.name().substr(1) << ".h\",\n";
                    out << "\"" << pathPrefix << "Bs" << fqName.name().substr(1) << ".h\",\n";
                }
            });

    // C++ library definition
    out << "cc_library_shared {\n";
    out.indent();
    out << "name: \"" << libraryName << "\",\n"
        << "generated_sources: [\"" << genSourceName << "\"],\n"
        << "generated_headers: [\"" << genHeaderName << "\"],\n"
        << "export_generated_headers: [\"" << genHeaderName << "\"],\n"
        << "shared_libs: [\n";

    out.indent();
    out << "\"libhidl\",\n"
        << "\"libhwbinder\",\n"
        << "\"libutils\",\n"
        << "\"libcutils\",\n";
    for (const auto &importedPackage : importedPackages) {
        out << "\"" << makeLibraryName(importedPackage) << "\",\n";
    }
    out.unindent();

    out << "],\n";

    out << "export_shared_lib_headers: [\n";
    out.indent();
    out << "\"libhidl\",\n"
        << "\"libhwbinder\",\n"
        << "\"libutils\",\n";
    for (const auto &importedPackage : importedPackages) {
        out << "\"" << makeLibraryName(importedPackage) << "\",\n";
    }
    out.unindent();
    out << "],\n";
    out.unindent();

    out << "}\n";

    return OK;
}

static status_t generateMakefileImplForPackage(
        const FQName &packageFQName,
        const char *,
        Coordinator *coordinator,
        const std::string &outputDir) {

    const std::string libraryName = makeLibraryName(packageFQName) + "-impl";

    std::vector<FQName> packageInterfaces;

    status_t err =
        coordinator->appendPackageInterfacesToVector(packageFQName,
                                                     &packageInterfaces);

    if (err != OK) {
        return err;
    }

    std::set<FQName> importedPackages;

    for (const auto &fqName : packageInterfaces) {
        AST *ast = coordinator->parse(fqName);

        if (ast == NULL) {
            fprintf(stderr,
                    "ERROR: Could not parse %s. Aborting.\n",
                    fqName.string().c_str());

            return UNKNOWN_ERROR;
        }

        ast->getImportedPackages(&importedPackages);
    }

    std::string path = outputDir + "Android.mk";

    CHECK(Coordinator::MakeParentHierarchy(path));
    FILE *file = fopen(path.c_str(), "w");

    if (file == NULL) {
        return -errno;
    }

    Formatter out(file);

    out << "LOCAL_PATH := $(call my-dir)\n\n"
        << "include $(CLEAR_VARS)\n"
        << "LOCAL_MODULE := " << libraryName << "\n"
        << "LOCAL_MODULE_RELATIVE_PATH := hw\n"
        << "LOCAL_SRC_FILES := \\\n";
    out.indent();
    for (const auto &fqName : packageInterfaces) {
        if (fqName.name() == "types") {
            continue;
        }
        out << fqName.getInterfaceBaseName() << ".cpp \\\n";
    }
    out.unindent();
    out << "\n";
    out << "LOCAL_SHARED_LIBRARIES := \\\n";
    out.indent();
    out << "libhidl \\\n"
        << "libhwbinder \\\n"
        << "libutils \\\n"
        << makeLibraryName(packageFQName) << " \\\n";

    for (const auto &importedPackage : importedPackages) {
        out << makeLibraryName(importedPackage)
            << " \\\n";
    }
    out.unindent();
    out << "\n";

    out << "include $(BUILD_SHARED_LIBRARY)\n";

    return OK;
}

OutputHandler::ValRes validateForSource(
        const FQName &fqName, const std::string &language) {
    if (fqName.package().empty()) {
        fprintf(stderr, "ERROR: Expecting package name\n");
        return OutputHandler::FAILED;
    }

    if (fqName.version().empty()) {
        fprintf(stderr, "ERROR: Expecting package version\n");
        return OutputHandler::FAILED;
    }

    const std::string &name = fqName.name();
    if (!name.empty()) {
        if (name.find('.') == std::string::npos) {
            return OutputHandler::PASS_FULL;
        }

        if (language != "java" || name.find("types.") != 0) {
            // When generating java sources for "types.hal", output can be
            // constrained to just one of the top-level types declared
            // by using the extended syntax
            // android.hardware.Foo@1.0::types.TopLevelTypeName.
            // In all other cases (different language, not 'types') the dot
            // notation in the name is illegal in this context.
            return OutputHandler::FAILED;
        }

        return OutputHandler::PASS_FULL;
    }

    return OutputHandler::PASS_PACKAGE;
}

OutputHandler::ValRes validateForExportHeader(
        const FQName &fqName, const std::string & /* language */) {
    if (fqName.package().empty()) {
        fprintf(stderr, "ERROR: Expecting package name\n");
        return OutputHandler::FAILED;
    }

    if (fqName.version().empty()) {
        fprintf(stderr, "ERROR: Expecting package version\n");
        return OutputHandler::FAILED;
    }

    if (!fqName.name().empty()) {
        fprintf(stderr,
                "ERROR: Expecting only package name and version.\n");
        return OutputHandler::FAILED;
    }

    return OutputHandler::PASS_PACKAGE;
}


static status_t generateExportHeaderForPackage(
        const FQName &packageFQName,
        const char * /* hidl_gen */,
        Coordinator *coordinator,
        const std::string &outputPath,
        bool forJava) {

    CHECK(packageFQName.isValid()
            && !packageFQName.isFullyQualified()
            && packageFQName.name().empty());

    std::vector<FQName> packageInterfaces;

    status_t err = coordinator->appendPackageInterfacesToVector(
            packageFQName, &packageInterfaces);

    if (err != OK) {
        return err;
    }

    std::vector<const Type *> exportedTypes;

    for (const auto &fqName : packageInterfaces) {
        AST *ast = coordinator->parse(fqName);

        if (ast == NULL) {
            fprintf(stderr,
                    "ERROR: Could not parse %s. Aborting.\n",
                    fqName.string().c_str());

            return UNKNOWN_ERROR;
        }

        ast->appendToExportedTypesVector(&exportedTypes);
    }

    if (exportedTypes.empty()) {
        return OK;
    }

    std::string path = outputPath;

    if (forJava) {
        path.append(coordinator->convertPackageRootToPath(packageFQName));

        path.append(coordinator->getPackagePath(
                    packageFQName, true /* relative */));

        path.append("Constants.java");
    }

    CHECK(Coordinator::MakeParentHierarchy(path));
    FILE *file = fopen(path.c_str(), "w");

    if (file == nullptr) {
        return -errno;
    }

    Formatter out(file);

    out << "// This file is autogenerated by hidl-gen. Do not edit manually."
           "\n\n";

    std::string guard;
    if (forJava) {
        out << "package " << packageFQName.javaPackage() << ";\n\n";
        out << "public class Constants {\n";
        out.indent();
    } else {
        guard = "HIDL_GENERATED_";
        guard += packageFQName.tokenName();
        guard += "_";
        guard += "EXPORTED_CONSTANTS_H_";

        out << "#ifndef "
            << guard
            << "\n#define "
            << guard
            << "\n\n#ifdef __cplusplus\nextern \"C\" {\n#endif\n\n";
    }

    for (const auto &type : exportedTypes) {
        type->emitExportedHeader(out, forJava);
    }

    if (forJava) {
        out.unindent();
        out << "}\n";
    } else {
        out << "#ifdef __cplusplus\n}\n#endif\n\n#endif  // "
            << guard
            << "\n";
    }

    return OK;
}

static std::vector<OutputHandler> formats = {
    {"c++",
     OutputHandler::NEEDS_DIR /* mOutputMode */,
     validateForSource,
     [](const FQName &fqName,
        const char *hidl_gen, Coordinator *coordinator,
        const std::string &outputDir) -> status_t {
            if (fqName.isFullyQualified()) {
                        return generateSourcesForFile(fqName,
                                                      hidl_gen,
                                                      coordinator,
                                                      outputDir,
                                                      "c++");
            } else {
                        return generateSourcesForPackage(fqName,
                                                         hidl_gen,
                                                         coordinator,
                                                         outputDir,
                                                         "c++");
            }
        }
    },

    {"export-header",
     OutputHandler::NEEDS_FILE /* mOutputMode */,
     validateForExportHeader,
     [](const FQName &fqName,
        const char *hidl_gen,
        Coordinator *coordinator,
        const std::string &outputPath) -> status_t {
            CHECK(!fqName.isFullyQualified());

            return generateExportHeaderForPackage(
                    fqName,
                    hidl_gen,
                    coordinator,
                    outputPath,
                    false /* forJava */);
        }
    },

    {"c++-impl",
     OutputHandler::NEEDS_DIR /* mOutputMode */,
     validateForSource,
     [](const FQName &fqName,
        const char *hidl_gen, Coordinator *coordinator,
        const std::string &outputDir) -> status_t {
            if (fqName.isFullyQualified()) {
                        return generateSourcesForFile(fqName,
                                                      hidl_gen,
                                                      coordinator,
                                                      outputDir, "c++-impl");
            } else {
                        return generateSourcesForPackage(fqName,
                                                         hidl_gen,
                                                         coordinator,
                                                         outputDir, "c++-impl");
            }
        }
    },


    {"java",
     OutputHandler::NEEDS_DIR /* mOutputMode */,
     validateForSource,
     [](const FQName &fqName,
        const char *hidl_gen, Coordinator *coordinator,
        const std::string &outputDir) -> status_t {
            if (fqName.isFullyQualified()) {
                return generateSourcesForFile(fqName,
                                              hidl_gen,
                                              coordinator,
                                              outputDir,
                                              "java");
            }
            else {
                return generateSourcesForPackage(fqName,
                                                 hidl_gen,
                                                 coordinator,
                                                 outputDir,
                                                 "java");
            }
        }
    },

    {"java-constants",
     OutputHandler::NEEDS_DIR /* mOutputMode */,
     validateForExportHeader,
     [](const FQName &fqName,
        const char *hidl_gen, Coordinator *coordinator,
        const std::string &outputDir) -> status_t {
            CHECK(!fqName.isFullyQualified());
            return generateExportHeaderForPackage(
                    fqName,
                    hidl_gen,
                    coordinator,
                    outputDir,
                    true /* forJava */);
        }
    },

    {"vts",
     OutputHandler::NEEDS_DIR /* mOutputMode */,
     validateForSource,
     [](const FQName &fqName,
        const char * hidl_gen,
        Coordinator *coordinator,
        const std::string &outputDir) -> status_t {
            if (fqName.isFullyQualified()) {
                return generateSourcesForFile(fqName,
                                              hidl_gen,
                                              coordinator,
                                              outputDir, "vts");
            } else {
                return generateSourcesForPackage(fqName,
                                                 hidl_gen,
                                                 coordinator,
                                                 outputDir, "vts");
            }
       }
    },

    {"makefile",
     OutputHandler::NOT_NEEDED /* mOutputMode */,
     validateForMakefile,
     generateMakefileForPackage,
    },

    {"androidbp",
     OutputHandler::NOT_NEEDED /* mOutputMode */,
     validateForMakefile,
     generateAndroidBpForPackage,
    },

    {"makefile-impl",
     OutputHandler::NEEDS_DIR /* mOutputMode */,
     validateForMakefile,
     generateMakefileImplForPackage,
    }
};

static void usage(const char *me) {
    fprintf(stderr,
            "usage: %s -o output-path -L <language> (-r interface-root)+ fqname+\n",
            me);

    fprintf(stderr, "         -o output path\n");

    fprintf(stderr, "         -L <language> (one of");
    for (auto &e : formats) {
        fprintf(stderr, " %s", e.mKey.c_str());
    }
    fprintf(stderr, ")\n");

    fprintf(stderr,
            "         -r package:path root "
            "(e.g., android.hardware:hardware/interfaces)\n");
}

int main(int argc, char **argv) {
    std::string outputPath;
    std::vector<std::string> packageRootPaths;
    std::vector<std::string> packageRoots;

    const char *me = argv[0];
    OutputHandler *outputFormat = nullptr;

    int res;
    while ((res = getopt(argc, argv, "ho:r:L:")) >= 0) {
        switch (res) {
            case 'o':
            {
                outputPath = optarg;
                break;
            }

            case 'r':
            {
                std::string val(optarg);
                auto index = val.find_first_of(':');
                CHECK(index != std::string::npos);

                auto package = val.substr(0, index);
                auto path = val.substr(index + 1);
                packageRootPaths.push_back(path);
                packageRoots.push_back(package);
                break;
            }

            case 'L':
            {
                CHECK(outputFormat == nullptr); // only one -L option
                for (auto &e : formats) {
                    if (e.mKey == optarg) {
                        outputFormat = &e;
                        break;
                    }
                }
                CHECK(outputFormat != nullptr);
                break;
            }

            case '?':
            case 'h':
            default:
            {
                usage(me);
                exit(1);
                break;
            }
        }
    }

    if (outputFormat == nullptr) {
        usage(me);
        exit(1);
    }

    argc -= optind;
    argv += optind;

    if (packageRootPaths.empty()) {
        // Pick reasonable defaults.

        packageRoots.push_back("android.hardware");

        const char *TOP = getenv("TOP");
        if (TOP == nullptr) {
            fprintf(stderr,
                    "ERROR: No root path (-r) specified"
                    " and $TOP environment variable not set.\n");
            exit(1);
        }

        std::string path = TOP;
        path.append("/hardware/interfaces");

        packageRootPaths.push_back(path);
    }

    // Valid options are now in argv[0] .. argv[argc - 1].

    switch (outputFormat->mOutputMode) {
        case OutputHandler::NEEDS_DIR:
        case OutputHandler::NEEDS_FILE:
        {
            if (outputPath.empty()) {
                usage(me);
                exit(1);
            }

            if (outputFormat->mOutputMode == OutputHandler::NEEDS_DIR) {
                const size_t len = outputPath.size();
                if (outputPath[len - 1] != '/') {
                    outputPath += "/";
                }
            }
            break;
        }

        default:
            outputPath.clear();  // Unused.
            break;
    }

    Coordinator coordinator(packageRootPaths, packageRoots);

    for (int i = 0; i < argc; ++i) {
        FQName fqName(argv[i]);

        if (!fqName.isValid()) {
            fprintf(stderr,
                    "ERROR: Invalid fully-qualified name.\n");
            exit(1);
        }

        OutputHandler::ValRes valid =
            outputFormat->validate(fqName, outputFormat->mKey);

        if (valid == OutputHandler::FAILED) {
            exit(1);
        }

        status_t err =
            outputFormat->generate(fqName, me, &coordinator, outputPath);

        if (err != OK) {
            exit(1);
        }
    }

    return 0;
}