/*
 * Copyright (C) Tristan Franssen, <tristanfranssen@strawhats.nl>.
 *
 * This software is 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 in the file LICENSE or at
 * http://www.apache.org/licenses/LICENSE-2.0
 */
#include "cosms-core/file.h"

#include <stdlib.h>
#include <stdint.h>
#include <limits.h>

#if defined(__GNUC__)
#define _FILE_OFFSET_BITS_ 64

#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <errno.h>
#elif defined(_WIN32)
#include <windows.h>
#endif

CosmsCoreFileError cosms_core_file_read(const char *path, char **content, unsigned long long *size) {
    #if defined(__GNUC__)
    int file = open(path, O_RDONLY);
    if (file == -1) {
        switch(errno) {
            case ENOENT: 
                return COSMS_CORE_FILE_NOT_FOUND;

            case EACCES:
                return COSMS_CORE_FILE_NO_ACCESS;

            case EMFILE:
            case ENFILE:
                return COSMS_CORE_FILE_LIMIT_REACHED;

            default:
                return COSMS_CORE_FILE_UNKOWN_ERROR;
        }
    }
    
    struct stat file_stat;
    if (stat(path, &file_stat) != 0) {
        close(file);
        return COSMS_CORE_FILE_COULD_NOT_READ_SIZE;
    }

    if (size != NULL) {
        *size = file_stat.st_size;
    }

    *content = (char*)malloc((file_stat.st_size + 1) * sizeof(char));
    if (content == NULL) {
        close(file);
        return COSMS_CORE_FILE_FAILED_TO_ALLOCATE;
    }
    
    unsigned long long remaining_bytes = file_stat.st_size;
    while (remaining_bytes != 0) {
        unsigned int bytes_to_read;
        if (remaining_bytes > UINT_MAX) {
            bytes_to_read = UINT_MAX;
        } else {
            bytes_to_read = (unsigned int)remaining_bytes;
        }

        int read_bytes = read(file, (*content) + (file_stat.st_size - remaining_bytes), bytes_to_read);
        if (read_bytes == -1) {
            free(*content);
            close(file);
            return COSMS_CORE_FILE_FAILED_TO_READ;
        }

        remaining_bytes -= read_bytes;
    }
    
    (*content)[file_stat.st_size] = '\0';
    close(file);
    #elif defined(_WIN32)
    HANDLE file = CreateFile(path, GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
    if (file == INVALID_HANDLE_VALUE) {
        switch(GetLastError()) {
            case ERROR_FILE_NOT_FOUND:
            case ERROR_PATH_NOT_FOUND:
                return COSMS_CORE_FILE_NOT_FOUND;

            case ERROR_ACCESS_DENIED:
            case ERROR_SHARING_VIOLATION:
            case ERROR_LOCK_VIOLATION:
                return COSMS_CORE_FILE_NO_ACCESS;

            case ERROR_TOO_MANY_OPEN_FILES:
                return COSMS_CORE_FILE_LIMIT_REACHED;

            default:
                return COSMS_CORE_FILE_UNKOWN_ERROR;
        }
    }

    DWORD high_size;
    DWORD low_size = GetFileSize(file, &high_size);
    if (low_size == INVALID_FILE_SIZE && GetLastError() != NO_ERROR) {
        CloseHandle(file);
        return COSMS_CORE_FILE_COULD_NOT_READ_SIZE;
    }

    unsigned long long file_size = ((unsigned long long)high_size << 32) | low_size;

    if (size != NULL) {
        *size = file_size;
    }

    *content = (char*)malloc((file_size + 1) * sizeof(char));
    if (content == NULL) {
        CloseHandle(file);
        return COSMS_CORE_FILE_FAILED_TO_ALLOCATE;
    }

    unsigned long long remaining_bytes = file_size;
    while (remaining_bytes != 0) {
        DWORD bytes_to_read, read_bytes;
        if (remaining_bytes > UINT_MAX) {
            bytes_to_read = UINT_MAX;
        } else {
            bytes_to_read = (DWORD)remaining_bytes;
        }

        if (!ReadFile(file, (*content) + (file_size - remaining_bytes), bytes_to_read, &read_bytes, NULL)) {
            free(*content);
            CloseHandle(file);
            return COSMS_CORE_FILE_FAILED_TO_READ;
        }

        remaining_bytes -= read_bytes;
    }

    (*content)[file_size] = '\0';
    CloseHandle(file);
    #endif

    return COSMS_CORE_FILE_OK;
}

CosmsCoreFileError cosms_core_file_write(const char *path, const char *content, unsigned long long size, bool override) {
    #if defined(__GNUC__)
    int file;
    if (override) {
        file = open(path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
    } else {
        file = open(path, O_WRONLY | O_CREAT | O_APPEND, 0644);
    }

    if (file == -1) {
        switch (errno) {
            case ENOENT:
                return COSMS_CORE_FILE_NOT_FOUND;

            case EACCES:
                return COSMS_CORE_FILE_NO_ACCESS;

            case EMFILE:
            case ENFILE:
                return COSMS_CORE_FILE_LIMIT_REACHED;

            default:
                return COSMS_CORE_FILE_UNKOWN_ERROR;
        }
    }

    unsigned long long remaining_bytes = size;
    while (remaining_bytes != 0) {
        unsigned int bytes_to_write;
        if (remaining_bytes > UINT_MAX) {
            bytes_to_write = UINT_MAX;
        } else {
            bytes_to_write = (unsigned int)remaining_bytes;
        }

        int written_bytes = write(file, content + (size - remaining_bytes), bytes_to_write);
        if (written_bytes == -1) {
            close(file);
            return COSMS_CORE_FILE_FAILED_TO_WRITE;
        }

        remaining_bytes -= written_bytes;
    }

    close(file);
    #elif defined(_WIN32)
    HANDLE file;
    if (override) {
        file = CreateFile(path, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
    } else {
        file = CreateFile(path, FILE_APPEND_DATA, 0, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
    }

    if (file == INVALID_HANDLE_VALUE) {
        switch(GetLastError()) {
            case ERROR_FILE_NOT_FOUND:
            case ERROR_PATH_NOT_FOUND:
                return COSMS_CORE_FILE_NOT_FOUND;

            case ERROR_ACCESS_DENIED:
            case ERROR_SHARING_VIOLATION:
            case ERROR_LOCK_VIOLATION:
                return COSMS_CORE_FILE_NO_ACCESS;

            case ERROR_TOO_MANY_OPEN_FILES:
                return COSMS_CORE_FILE_LIMIT_REACHED;

            default:
                return COSMS_CORE_FILE_UNKOWN_ERROR;
        }
    }

    unsigned long long remaining_bytes = size;
    while (remaining_bytes != 0) {
        DWORD bytes_to_write, written_bytes;
        if (remaining_bytes > UINT_MAX) {
            bytes_to_write = UINT_MAX;
        } else {
            bytes_to_write = (DWORD)remaining_bytes;
        }

        if (!WriteFile(file, content + (size - remaining_bytes), bytes_to_write, &written_bytes, NULL)) {
            CloseHandle(file);
            return COSMS_CORE_FILE_FAILED_TO_WRITE;
        }

        remaining_bytes -= written_bytes;
    }

    CloseHandle(file);
    #endif

    return COSMS_CORE_FILE_OK;
}

CosmsCoreFileError cosms_core_file_delete(const char *path) {
    #if defined(__GNUC__)
    if (unlink(path) == -1) {
        switch (errno) {
            case ENOENT:
                return COSMS_CORE_FILE_NOT_FOUND;

            case EACCES:
                return COSMS_CORE_FILE_NO_ACCESS;

            case EBUSY:
                return COSMS_CORE_FILE_STILL_OPEN;

            default:
                return COSMS_CORE_FILE_UNKOWN_ERROR;
        }
    }
    #elif defined(_WIN32)
    if (!DeleteFile(path)) {
        switch(GetLastError()) {
            case ERROR_FILE_NOT_FOUND:
            case ERROR_PATH_NOT_FOUND:
                return COSMS_CORE_FILE_NOT_FOUND;

            case ERROR_ACCESS_DENIED:
                return COSMS_CORE_FILE_NO_ACCESS;

            case ERROR_LOCK_VIOLATION:
            case ERROR_SHARING_VIOLATION:
                return COSMS_CORE_FILE_STILL_OPEN;

            default:
                return COSMS_CORE_FILE_UNKOWN_ERROR;
        }
    }
    #endif

    return COSMS_CORE_FILE_OK;
}

const char *cosms_core_file_error_string(CosmsCoreFileError error) {
    switch(error) {
        case COSMS_CORE_FILE_OK:
            return "cosms-file everything ok";

        case COSMS_CORE_FILE_NOT_FOUND:
            return "cosms-file path not found";

        case COSMS_CORE_FILE_NO_ACCESS:
            return "cosms-file no access";

        case COSMS_CORE_FILE_LIMIT_REACHED:
            return "cosms-file to many open files";

        case COSMS_CORE_FILE_COULD_NOT_READ_SIZE:
            return "cosms-file failed to read size";

        case COSMS_CORE_FILE_UNKOWN_ERROR:
            return "cosms-file unkown error occured";

        case COSMS_CORE_FILE_FAILED_TO_ALLOCATE:
            return "cosms-file failed to allocate memory";

        case COSMS_CORE_FILE_FAILED_TO_READ:
            return "cosms-file failed to read content of file";

        case COSMS_CORE_FILE_FAILED_TO_WRITE:
            return "cosms-file failed to write content to file";

        case COSMS_CORE_FILE_STILL_OPEN:
            return "cosms-file still open";

        default:
            return NULL;
    }
}