#define _FILE_OFFSET_BITS 64

#include "../CgeFile.h"
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>

static const int64_t off_t_max =
    (sizeof(off_t) == 8) ? INT64_MAX :
    (sizeof(off_t) == 4) ? INT32_MAX : 0;

static const int64_t off_t_min =
    (sizeof(off_t) == 8) ? INT64_MIN :
    (sizeof(off_t) == 4) ? INT32_MIN : 0;

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

static int errnoToFileCode(int err) {
    switch (err) {
        case 0:
            return CGE_FILE_EOK;

        case ENOMEM:
            return CGE_FILE_EOOM;

        case ENOSPC:
            return CGE_FILE_ENOSPC;

        case EINVAL:
            return CGE_FILE_EINVAL;

        case ENOENT:
            return CGE_FILE_ENOENT;

        case EACCES:
        case EPERM:
            return CGE_FILE_EACCES;

        case EROFS:
            return CGE_FILE_EROFS;

        case EEXIST:
            return CGE_FILE_EEXIST;

        case EISDIR:
            return CGE_FILE_EISDIR;

        case EMFILE:
        case ENFILE:
            return CGE_FILE_EMFILE;

        case ENAMETOOLONG:
            return CGE_FILE_ENAMETOOLONG;

        default:
            return CGE_FILE_EUNKNOWN;
    }
}

static int fileOpenFlags(int mode) {
    int flags = 0;

    if ((mode & CGE_FILE_READWRITE) == CGE_FILE_READWRITE)
        flags |= O_RDWR;
    else if (mode & CGE_FILE_WRITE)
        flags |= O_WRONLY;
    else if (mode & CGE_FILE_READ)
        flags |= O_RDONLY;
    else
        return -1;

    if (!(mode & CGE_FILE_EXIST))
    {
        flags |= O_CREAT;
        if (mode & CGE_FILE_CREATE)
            flags |= O_EXCL;
    }

    if (mode & CGE_FILE_APPEND)
        flags |= O_APPEND;

    if (mode & CGE_FILE_TRUNCATE)
        flags |= O_TRUNC;

    return flags;
}

static int fileInit(CgeFile *file, const char *path, int mode) {
    static const mode_t openMode = (S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
    int flags;

    if (!path)
        return CGE_FILE_EINVAL;

    flags = fileOpenFlags(mode);
    if (flags == -1)
        return CGE_FILE_EINVAL;

    file->flags = 0;
    file->handle = open(path, flags, openMode);
    if (file->handle == -1)
        return errnoToFileCode(errno);

    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) {
    close(file->handle);
    free(file);
}

int CgeFileRead(CgeFile *file, void *buffer, size_t size, size_t *actual) {
    ssize_t readed;

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

    readed = read(file->handle, buffer, size);
    if (readed < 0)
        goto error;

    if (readed > 0) 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 = errnoToFileCode(errno);
    return 0;
}

int CgeFileWrite(CgeFile *file, const void *buffer, size_t size,
                 size_t *actual) {
    ssize_t written;

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

    written = write(file->handle, buffer, size);
    if (written < 0)
        goto error;

    if (actual) *actual = written;
    return 1;

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

int CgeFileTell(CgeFile *file, int64_t *offset) {
    if (file->flags & CGE_FILE_ERROR)
        return 0;

    if ((*offset = lseek(file->handle, 0, SEEK_CUR)) == -1)
        goto error;

    return 1;

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

int CgeFileSeek(CgeFile *file, int64_t offset, int whence) {
    if (file->flags & CGE_FILE_ERROR)
        return 0;

    if (offset < off_t_min || offset > off_t_max) {
        file->flags |= CGE_FILE_ERROR;
        file->lastError = CGE_FILE_EINVAL;
        return 0;
    }

    if (lseek(file->handle, offset, whence) == -1)
        goto error;

    return 1;

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

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

    return 1;

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

int CgeFileSize(CgeFile *file, int64_t *size) {
    struct stat sb;

    if (fstat(file->handle, &sb))
        goto error;

    *size = sb.st_size;
    return 1;

error:
    file->flags |= CGE_FILE_ERROR;
    file->lastError = errnoToFileCode(errno);
    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;
}