#include "storage/file_handle.h"

#include <cmath>

#include "common/file_system/virtual_file_system.h"
#include "storage/buffer_manager/buffer_manager.h"

using namespace lbug::common;

namespace lbug {
namespace storage {

FileHandle::FileHandle(const std::string& path, uint8_t fhFlags, BufferManager* bm,
    uint32_t fileIndex, VirtualFileSystem* vfs, main::ClientContext* context)
    : fhFlags{fhFlags}, fileIndex{fileIndex}, numPages{0}, pageCapacity{0}, bm{bm},
      pageSizeClass{isNewTmpFile() && isLargePaged() ? TEMP_PAGE : REGULAR_PAGE}, pageStates{0, 0},
      frameGroupIdxes{0, 0}, pageManager(std::make_unique<PageManager>(this)) {
    if (isNewTmpFile()) {
        constructTmpFileHandle(path);
    } else {
        constructPersistentFileHandle(path, vfs, context);
    }
    pageStates = ConcurrentVector<PageState, StorageConstants::PAGE_GROUP_SIZE,
        TEMP_PAGE_SIZE / sizeof(void*)>{numPages, pageCapacity};
    frameGroupIdxes = ConcurrentVector<page_group_idx_t>{getNumPageGroups(), getNumPageGroups()};
    for (auto i = 0u; i < frameGroupIdxes.size(); i++) {
        frameGroupIdxes[i] = bm->addNewFrameGroup(pageSizeClass);
    }
}

void FileHandle::constructPersistentFileHandle(const std::string& path, VirtualFileSystem* vfs,
    main::ClientContext* context) {
    FileOpenFlags openFlags{0};
    if (isReadOnlyFile()) {
        openFlags.flags = FileFlags::READ_ONLY;
        openFlags.lockType = isLockRequired() ? FileLockType::READ_LOCK : FileLockType::NO_LOCK;
    } else {
        openFlags.flags =
            FileFlags::WRITE | FileFlags::READ_ONLY |
            ((createFileIfNotExists()) ? FileFlags::CREATE_IF_NOT_EXISTS : 0x00000000);
        openFlags.lockType = isLockRequired() ? FileLockType::WRITE_LOCK : FileLockType::NO_LOCK;
    }
    fileInfo = vfs->openFile(path, openFlags, context);
    const auto fileLength = fileInfo->getFileSize();
    numPages = ceil(static_cast<double>(fileLength) / static_cast<double>(getPageSize()));
    pageCapacity = 0;
    while (pageCapacity < numPages) {
        pageCapacity += StorageConstants::PAGE_GROUP_SIZE;
    }
}

void FileHandle::constructTmpFileHandle(const std::string& path) {
    fileInfo = std::make_unique<FileInfo>(path, nullptr);
    numPages = 0;
    pageCapacity = 0;
}

page_idx_t FileHandle::addNewPage() {
    return addNewPages(1 /* numNewPages */);
}

page_idx_t FileHandle::addNewPages(page_idx_t numNewPages) {
    std::unique_lock lck{fhSharedMutex, std::defer_lock_t{}};
    while (!lck.try_lock()) {}
    const auto numPagesBeforeChange = numPages.load();
    for (auto i = 0u; i < numNewPages; i++) {
        addNewPageWithoutLock();
    }
    return numPagesBeforeChange;
}

page_idx_t FileHandle::addNewPageWithoutLock() {
    if (numPages == pageCapacity) {
        addNewPageGroupWithoutLock();
    }
    pageStates[numPages].resetToEvicted();
    const auto pageIdx = numPages++;
    if (isInMemoryMode()) {
        bm->pin(*this, pageIdx, PageReadPolicy::DONT_READ_PAGE);
    }
    return pageIdx;
}

void FileHandle::addNewPageGroupWithoutLock() {
    pageCapacity += StorageConstants::PAGE_GROUP_SIZE;
    pageStates.resize(pageCapacity);
    frameGroupIdxes.push_back(bm->addNewFrameGroup(pageSizeClass));
}

uint8_t* FileHandle::pinPage(page_idx_t pageIdx, PageReadPolicy readPolicy) {
    if (isInMemoryMode()) {
        // Already pinned.
        return bm->getFrame(*this, pageIdx);
    }
    return bm->pin(*this, pageIdx, readPolicy);
}

void FileHandle::optimisticReadPage(page_idx_t pageIdx,
    const std::function<void(uint8_t*)>& readOp) {
    if (isInMemoryMode()) {
        DASSERT(
            PageState::getState(getPageState(pageIdx)->getStateAndVersion()) == PageState::LOCKED);
        const auto frame = bm->getFrame(*this, pageIdx);
        readOp(frame);
    } else {
        bm->optimisticRead(*this, pageIdx, readOp);
    }
}

void FileHandle::unpinPage(page_idx_t pageIdx) {
    bm->unpin(*this, pageIdx);
}

void FileHandle::resetToZeroPagesAndPageCapacity() {
    removePageIdxAndTruncateIfNecessary(0 /* pageIdx */);
    if (isInMemoryMode()) {
        for (auto i = 0u; i < numPages; i++) {
            bm->unpin(*this, i);
        }
    } else {
        fileInfo->truncate(0 /* size */);
    }
}

uint8_t* FileHandle::getFrame(page_idx_t pageIdx) {
    DASSERT(pageIdx < numPages);
    return bm->getFrame(*this, pageIdx);
}

void FileHandle::removePageIdxAndTruncateIfNecessary(page_idx_t pageIdx) {
    std::unique_lock xLck{fhSharedMutex};
    if (numPages <= pageIdx) {
        return;
    }
    numPages = pageIdx;
    pageStates.resize(numPages);
    const auto numPageGroups = getNumPageGroups();
    if (numPageGroups == frameGroupIdxes.size()) {
        return;
    }
    DASSERT(numPageGroups < frameGroupIdxes.size());
    frameGroupIdxes.resize(numPageGroups);
    pageCapacity = numPageGroups * StorageConstants::PAGE_GROUP_SIZE;
}

void FileHandle::removePageFromFrameIfNecessary(page_idx_t pageIdx) {
    bm->removePageFromFrameIfNecessary(*this, pageIdx);
}

void FileHandle::flushAllDirtyPagesInFrames() {
    for (auto pageIdx = 0u; pageIdx < numPages; ++pageIdx) {
        flushPageIfDirtyWithoutLock(pageIdx);
    }
}

void FileHandle::flushPageIfDirtyWithoutLock(page_idx_t pageIdx) {
    auto pageState = getPageState(pageIdx);
    if (!isInMemoryMode() && pageState->isDirty()) {
        fileInfo->writeFile(getFrame(pageIdx), getPageSize(), pageIdx * getPageSize());
        pageState->clearDirtyWithoutLock();
    }
}

void FileHandle::writePagesToFile(const uint8_t* buffer, uint64_t size, page_idx_t startPageIdx) {
    if (isInMemoryMode()) {
        auto pageSize = getPageSize();
        for (uint64_t i = 0; i < size; i += pageSize) {
            const auto frame = getFrame(startPageIdx + i / pageSize);
            memcpy(frame, buffer + i, std::min(pageSize, size - i));
        }
    } else {
        fileInfo->writeFile(buffer, size, startPageIdx * getPageSize());
    }
}

} // namespace storage
} // namespace lbug
