#include "../CgeFile.h"
#include <windows.h>

struct CgeFile {
    HANDLE handle;
    int flags;
    int mode;
    int lastError;
};

static int errorCodeFromError(void) {
    DWORD error;

    error = GetLastError();
    switch (error) {
    case ERROR_NOT_ENOUGH_MEMORY:
        return CGE_FILE_EOOM;

    case ERROR_FILE_NOT_FOUND:
    case ERROR_PATH_NOT_FOUND:
        return CGE_FILE_ENOENT;

    case ERROR_ACCESS_DENIED:
        return CGE_FILE_EACCES;

    case ERROR_FILE_EXISTS:
    case ERROR_ALREADY_EXISTS:
        return CGE_FILE_EEXIST;

    case ERROR_DIRECTORY:
        return CGE_FILE_EISDIR;

    case ERROR_WRITE_PROTECT:
        return CGE_FILE_EROFS;

    case ERROR_TOO_MANY_OPEN_FILES:
        return CGE_FILE_EMFILE;

    case ERROR_INVALID_NAME:
    case ERROR_FILENAME_EXCED_RANGE:
        return CGE_FILE_ENAMETOOLONG;

    case ERROR_DISK_FULL:
    case ERROR_HANDLE_DISK_FULL:
        return CGE_FILE_ENOSPC;

    default:
        return CGE_FILE_EUNKNOWN;
    }
}

static int fileInit(CgeFile *file, const char *path, int mode) {
    DWORD access = 0, how = 0;

    if (!path)
        return CGE_FILE_EINVAL;

    if (mode & CGE_FILE_READ)
        access |= GENERIC_READ;
    if (mode & CGE_FILE_WRITE)
        access |= GENERIC_WRITE;

    if (!access)
        return CGE_FILE_EINVAL;

    if (mode & CGE_FILE_TRUNCATE) {
        switch (mode & (CGE_FILE_CREATE | CGE_FILE_EXIST)) {
        case 0:               how = CREATE_ALWAYS;     break;
        case CGE_FILE_CREATE: how = CREATE_NEW;        break;
        case CGE_FILE_EXIST:  how = TRUNCATE_EXISTING; break;
        default:              return CGE_FILE_EINVAL;
        }
    } else {
        switch (mode & (CGE_FILE_CREATE | CGE_FILE_EXIST)) {
        case 0:               how = OPEN_ALWAYS;   break;
        case CGE_FILE_CREATE: how = CREATE_NEW;    break;
        case CGE_FILE_EXIST:  how = OPEN_EXISTING; break;
        default:              return CGE_FILE_EINVAL;
        }
    }

    file->flags = 0;
    file->mode = mode;
    file->handle = CreateFileA(path, access, FILE_SHARE_READ, NULL, how, FILE_ATTRIBUTE_NORMAL, NULL);

    if (file->handle == INVALID_HANDLE_VALUE)
        return errorCodeFromError();

    if (mode & CGE_FILE_TRUNCATE)
        SetEndOfFile(file->handle);

    return CGE_FILE_EOK;
}

CgeFile *CgeFileNew(const char *path, int mode, int *result) {
    CgeFile *file;
    int code = 0;

    if ((file = malloc(sizeof(*file)))) {
        if ((code = fileInit(file, path, mode))) {
            free(file);
            file = NULL;
        }
    }
    if (result) *result = code;
    return file;
}

void CgeFileFree(CgeFile *file) {
    CloseHandle(file->handle);
    free(file);
}

int CgeFileRead(CgeFile *file, char *buffer, size_t size, size_t *actual) {
    DWORD readed;

    if (file->flags & CGE_FILE_ERROR)
        return 0;

    if (!ReadFile(file->handle, buffer, (DWORD)size, &readed, NULL))
        goto error;

    if (!readed) file->flags |= CGE_FILE_EOF;
    else file->flags &= ~CGE_FILE_EOF;
    if (actual) *actual = readed;

    return 1;

error:
    file->flags |= CGE_FILE_ERROR;
    file->lastError = errorCodeFromError();
    return 0;
}

int CgeFileWrite(CgeFile *file, const char *buffer, size_t size,
                 size_t *actual) {
    DWORD written;
    LARGE_INTEGER position;

    if (file->flags & CGE_FILE_ERROR)
        return 0;

    if (file->mode & CGE_FILE_APPEND) {
        position.QuadPart = 0;
        if (!SetFilePointerEx(file->handle, position, NULL, FILE_END))
            goto error;
    }

    if (!WriteFile(file->handle, buffer, (DWORD)size, &written, NULL))
        goto error;

    if (actual) *actual = written;

    return 1;

error:
    file->flags |= CGE_FILE_ERROR;
    file->lastError = errorCodeFromError();
    return 0;
}

int CgeFileTell(CgeFile *file, int64_t *offset) {
    LARGE_INTEGER dummy, position;

    if (file->flags & CGE_FILE_ERROR)
        return 0;

    dummy.QuadPart = 0;
    if (!SetFilePointerEx(file->handle, dummy, &position, FILE_CURRENT))
        goto error;

    *offset = position.QuadPart;
    return 1;

error:
    file->flags |= CGE_FILE_ERROR;
    file->lastError = errorCodeFromError();
    return 0;
}

int CgeFileSeek(CgeFile *file, int64_t offset, int whence) {
    LARGE_INTEGER position;

    if (file->flags & CGE_FILE_ERROR)
        return 0;

    position.QuadPart = offset;
    if (!SetFilePointerEx(file->handle, position, NULL, whence))
        goto error;

    file->flags &= ~CGE_FILE_EOF;
    return 1;

error:
    file->flags |= CGE_FILE_ERROR;
    file->lastError = errorCodeFromError();
    return 0;
}

int CgeFileFlush(CgeFile *file) {
    if (!FlushFileBuffers(file->handle))
        goto error;

    return 1;

error:
    file->flags |= CGE_FILE_ERROR;
    file->lastError = errorCodeFromError();
    return 0;
}

int CgeFileSize(CgeFile *file, int64_t *size) {
    LARGE_INTEGER dummy;

    if (file->flags & CGE_FILE_ERROR)
        return 0;

    if (!GetFileSizeEx(file->handle, &dummy))
        goto error;

    *size = dummy.QuadPart;
    return 1;

error:
    file->flags |= CGE_FILE_ERROR;
    file->lastError = errorCodeFromError();
    return 0;
}

int CgeFileFlags(CgeFile *file, int *flags) {
    *flags = file->flags;
    return 1;
}

int CgeFileClear(CgeFile *file) {
    file->flags &= ~CGE_FILE_ERROR;
    return 1;
}

int CgeFileErrorCode(CgeFile *file) {
    return file->lastError;
}