#include "sqlite3.h"
#include <stdio.h>
#include <stdlib.h>

void execute_script(const char *database_path, const char *script_text);

int parse_arguments(int argc, char**argv, char **database_path, char **script_path);

char *read_file(const char *file_path);

const char *const PARAM_HELP = {
    "The following parameters are accepted:\n"
    "\t/d [database path] /s [script path]\n"
    "\t/s [script path] /d [database path]"
};

int main(int argc, char **argv)
{
    char *database_path, *script_path;

    if (parse_arguments(argc, argv, &database_path, &script_path))
    {
        char *script_text = read_file(script_path);

        if (script_text == NULL)
        {
            printf("unable to open file: %s\n", script_path);
        }
        else
        {
            execute_script(database_path, script_text);
            free(script_text);
        }
    }
    else
    {
        printf(PARAM_HELP);
    }
}

char *allocate_string(size_t string_length)
{
    char *result = malloc(string_length + 1);

    if (result != NULL)
    {
        result[string_length] = '\0';
    }
    return result;
}

void execute_script(const char *database_path, const char *script_text)
{
    sqlite3* database;
    const int error_code = sqlite3_open_v2(database_path, &database, SQLITE_OPEN_READWRITE, NULL);

    if (error_code)
    {
        printf("%s\n", sqlite3_errstr(error_code));
    }
    else
    {
        char *error_message = NULL;

        if (sqlite3_exec(database, script_text, NULL, NULL, &error_message))
        {
            printf("%s\n", error_message);
            sqlite3_free(error_message);
        }
    }
    sqlite3_close(database);
}

long file_length(FILE *file)
{
    const long initial = ftell(file);

    fseek(file, 0, SEEK_END);
    const long length = ftell(file);

    fseek(file, initial, SEEK_SET);

    return length;
}

const size_t VALID_ARGC = 5;

int parse_arguments(int argc, char**argv, char **database_path, char **script_path)
{
    *database_path = *script_path = NULL;

    if (argc == VALID_ARGC)
    {
        for (size_t i = 1; i < VALID_ARGC; ++i)
        {
            if (argv[i][0] != '/' || !argv[i][1] || argv[i][2]) return 0;

            switch (argv[i][1])
            {
            case 'd':
            case 'D':
                *database_path = argv[++i];
                break;
            case 's':
            case 'S':
                *script_path = argv[++i];
                break;
            default:
                return 0;
            }
        }
    }
    return *database_path && *script_path;
}

const char *const FILE_OPEN_MODE = "rb";

const size_t NUMBER_FILE_ELEMENTS = 1;

char* read_file(const char *file_path)
{
    char *text = NULL;
    FILE *file = fopen(file_path, FILE_OPEN_MODE);

    if (file)
    {
        const long file_size = file_length(file);

        if (file_size)
        {
            if ((text = allocate_string(file_size)))
            {
                if (fread(text, file_size, NUMBER_FILE_ELEMENTS, file) != NUMBER_FILE_ELEMENTS)
                {
                    free(text);
                    text = NULL;
                }
            }
        }
        fclose(file);
    }
    return text;
}