#define _GNU_SOURCE
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include <err.h>

void parser(FILE *fd);

int main(int argc, char **argv)
{
    if (argc <= 1)
    {
        fprintf(stderr, "Usage: ./parser FILE\n");
        return 1;
    }

    FILE *fd = fopen(argv[1], "r");
    if (!fd)
    {
        fprintf(stderr, "Error opening file '%s'\n", argv[0]);
        return 1;
    }

    parser(fd);

    fclose(fd);
    return 0;
}

char *get_id(char *buf, size_t buf_size, size_t *i)
{
    size_t start_nb = 0;
    short previous_number = 0;
    for (; *i < buf_size; *i += 1)
    {
        if ((buf[*i] >= '0' && buf[*i] <= '9') || buf[*i] == 'L' || buf[*i] == 'C')
        {
            if (!start_nb)
                start_nb = *i;
            previous_number = 1;
        }
        else if (previous_number)
        {
            buf[*i] = 0;
            return buf + start_nb;
        }
    }
    errx(2, "Error when compiling, pin number not found in a digitalWrite");
}

char *get_state(char *buf, size_t buf_size, size_t *i)
{
    for (; *i < buf_size - 3; *i += 1)
    {
        if (*i < buf_size - 4 && !strncmp("HIGH", buf + *i, 4))
        {
            buf[*i + 4] = 0;
            return buf + *i;
        }
        if (!strncmp("LOW", buf + *i, 3))
        {
            buf[*i + 3] = 0;
            return buf + *i;
        }
    }
    errx(2, "Error when compiling, HIGH or LOW not found in a digitalWrite");
}

void skip_end(char *buf, size_t buf_size, size_t *i)
{
    while (*i < buf_size && buf[*i] != ';')
        *i += 1;
    *i += 1;
}

size_t convert_fct(char *buf, size_t start, size_t buf_size, FILE *dst)
{
    const size_t size_str = strlen("digitalWrite");
    if (buf_size - start < size_str)
        return start;
    size_t index = start;
    if (!strncmp("digitalWrite", (buf + start), size_str))
    {
        index += size_str + 1;
        char *id = get_id(buf, buf_size, &index);
        char *state = get_state(buf, buf_size, &index);
        state[0] = (state[0] == 'H') ? '1' : '0';
        fwrite("set_pin(", 1, 8, dst);
        fwrite(id, 1, strlen(id), dst);
        fwrite(", ", 1, 2, dst);
        fwrite(state, 1, 1, dst);
        fwrite(", &row, &col, sequence, pointer);", 1, 33, dst);
        skip_end(buf, buf_size, &index);
    }
    else if (!strncmp("delay", (buf + start), 5))
    {
        index = buf_size;
    }
    return index;
}
void write_buf(char *buf, size_t start, size_t buf_size, FILE *dst, size_t *nb_bracket)
{
    for (size_t i = start; i < buf_size; i++)
    {
        if (buf[i] == '}') 
            *nb_bracket -= 1;
        else if (buf[i] == '{') 
            *nb_bracket += 1;
        
        if (nb_bracket != 0)
        {
            size_t index = convert_fct(buf, i, buf_size, dst);
            if (index < buf_size)
                fwrite(buf + index, 1, 1, dst);
            i = index;
        }
    }
}

size_t find_loop(char *buf, size_t buf_size)
{
    for (size_t i = 0; i < buf_size - 6; i++)
    {
        if (!strncmp("loop()", (buf + i), 6))
        {
            return i + 6;
        }
    }
    return buf_size + 1;
}

FILE *init_student()
{
    FILE *student = fopen("./src/student.c", "w+");
    FILE *default_student = fopen("./src/default_student.c", "r");
    if (!student)
        errx(1, "Failed to create file 'student.c'");
    if (!default_student)
    {
        fclose(student);
        errx(1, "Failed to open file 'default_student.c'");
    }    
    int c;
    while ((c = fgetc(default_student)) != EOF)
        fputc(c, student);
    fclose (default_student);
    return student;
}

void parser(FILE *fd)
{
    char *buf = NULL;
    size_t buf_size = 0;
    ssize_t bytes_read = 0;
    size_t nb_bracket = -1;
    short in_loop = 0;
    FILE *student = init_student();
    while ((bytes_read = getline(&buf, &buf_size, fd)) != -1)
    {
        if (in_loop)
        {
            write_buf(buf, 0, bytes_read, student, &nb_bracket);
        }
        else
        {
            size_t index_loop = find_loop(buf, buf_size);
            if (index_loop != buf_size + 1)
            {
                in_loop = 1;
            }
        }
    }
    if (buf)
        free(buf);
    fclose(student);
    if (!in_loop)
        errx(2, "Could not find the main loop function");
}