/*
 * (C) Copyright 1996- ECMWF.
 *
 * This software is licensed under the terms of the Apache Licence Version 2.0
 * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
 * In applying this licence, ECMWF does not waive the privileges and immunities
 * granted to it by virtue of its status as an intergovernmental organisation nor
 * does it submit to any jurisdiction.
 */

#include <cstring>

#include "eckit/config/Resource.h"
#include "eckit/filesystem/PathName.h"
#include "eckit/io/Buffer.h"
#include "eckit/io/FileHandle.h"
#include "eckit/io/MemoryHandle.h"
#include "eckit/io/MultiHandle.h"
#include "eckit/io/PartFileHandle.h"
#include "eckit/log/Log.h"
#include "eckit/memory/Zero.h"
#include "eckit/runtime/Tool.h"
#include "eckit/testing/Test.h"
#include "eckit/types/Types.h"

using namespace std;
using namespace eckit;
using namespace eckit::testing;

namespace eckit::test {

//----------------------------------------------------------------------------------------------------------------------

const char buf1[] = "abcdefghijklmnopqrstuvwxyz01234";

class Tester {
public:
    Tester() {

        format(std::cout, Log::fullFormat);

        std::string base = Resource<std::string>("$TMPDIR", "/tmp");
        path1_           = PathName::unique(base + "/path1");
        path1_ += ".dat";

        {
            FileHandle f1(path1_);
            f1.openForWrite(0);
            f1.write(buf1, sizeof(buf1) - 1);
            f1.close();
            std::cout << "created: " << path1_ << std::endl;
        }
    }

    ~Tester() {
        bool verbose = false;
        path1_.unlink(verbose);
    }

    static Buffer makeBuffer() {
        Buffer buffer(64);
        buffer.zero();
        return buffer;
    }

    PathName path1_;
};

//----------------------------------------------------------------------------------------------------------------------

CASE("PartFileHandle with no parts (empty)") {

    Tester test;

    OffsetList ol0 = {};
    LengthList ll0 = {};
    PartFileHandle ph(test.path1_, ol0, ll0);

    ph.openForRead();

    SECTION("Read @ start") {
        EXPECT_NO_THROW(ph.seek(0));
        {
            Buffer buff = Tester::makeBuffer();
            long r      = ph.read(buff, 10);
            EXPECT(r == 0);
        }
        EXPECT(ph.position() == Offset(0));
        EXPECT_NO_THROW(ph.skip(0));
    }

    SECTION("Seek beyond EOF throws, but we can still read without error") {
        EXPECT_THROWS_AS(ph.seek(1), AssertionFailed);
        EXPECT_NO_THROW(ph.seek(0));
        {
            Buffer buff = Tester::makeBuffer();
            long r      = ph.read(buff, 10);
            EXPECT(r == 0);
        }
        EXPECT(ph.position() == Offset(0));
        EXPECT_NO_THROW(ph.skip(0));
    }

    ph.close();
}

CASE("PartFileHandle with multiple parts") {

    Tester test;

    OffsetList ol1 = {0, 2, 6, 13, 23};
    LengthList ll1 = {1, 2, 4, 6, 8};

    PartFileHandle ph(test.path1_, ol1, ll1);

    // 0         1         2         3
    // 0123456789012345678901234567890
    // abcdefghijklmnopqrstuvwxyz01234
    // = ==  ====   ======    ========
    // a cd  ghij   nopqrs    xyz01234
    // size = 21

    ph.openForRead();

    SECTION("Seek to EOF") {

        EXPECT(ph.size() == Length(21));

        EXPECT_NO_THROW(ph.seek(21));
        {
            Buffer buff = Tester::makeBuffer();
            long r      = ph.read(buff, 10);
            EXPECT(r == 0);
        }

        EXPECT_NO_THROW(ph.seek(10));
        EXPECT(ph.position() == Offset(10));
        {
            Buffer buff = Tester::makeBuffer();
            long r      = ph.read(buff, 13);
            EXPECT(r == 11);
            std::cout << std::string(buff) << std::endl;
            EXPECT(std::string(buff) == "qrsxyz01234");
        }
        EXPECT(ph.position() == Offset(21));

        EXPECT_NO_THROW(ph.skip(-2));
        EXPECT(ph.position() == Offset(19));

        // skipping past the EOF asserts, and leaves position @ EOF
        {
            EXPECT_THROWS_AS(ph.skip(9), AssertionFailed);
            Offset position = ph.position();
            EXPECT_EQUAL(position, Offset(21));
            Buffer buff = Tester::makeBuffer();
            long r      = ph.read(buff, 10);
            EXPECT(r == 0);
        }

        // complete read
        {
            EXPECT_NO_THROW(ph.rewind());
            EXPECT(ph.position() == Offset(0));
            Buffer buff = Tester::makeBuffer();
            long r      = ph.read(buff, 40);
            EXPECT(r == 21);
            std::string read(buff);
            std::cout << read << std::endl;
            EXPECT_EQUAL(read, "acdghijnopqrsxyz01234");
        }

        // partial read in the middle and overlapping parts

        {
            EXPECT_NO_THROW(ph.seek(5));
            EXPECT(ph.position() == Offset(5));
            Buffer buff = Tester::makeBuffer();
            long r      = ph.read(buff, 12);
            EXPECT(r == 12);
            std::string read(buff);
            std::cout << read << std::endl;
            EXPECT_EQUAL(read, "ijnopqrsxyz0");
        }
    }

    ph.close();
}

//----------------------------------------------------------------------------------------------------------------------

}  // namespace eckit::test

int main(int argc, char** argv) {
    return run_tests(argc, argv);
}
