#include <stdio.h>
#include "buf.h"
#include <string.h>
#include <stdlib.h>

typedef enum {
    false,
    true
} bool;

FILE* getfile(int argc, char** argv){
    if (argc >= 2)
        return fopen(argv[1], "r");
    else
        return stdin;
}

FILE* in;
buf* inbuf;

int width = 80;
bool brk = false; // not implemented

size_t fillbuf(size_t len){ // returns real len
    int c;
    size_t set;
    for (set = buflen(inbuf); set < len && (c = fgetc(in)) != EOF;set++)
        inschrbuf(inbuf, c);
    return set;
}

size_t chrfill(char chr){
    size_t line;
    size_t len = buflen(inbuf);
    char* str = peekstrbuf(inbuf, 0, len);
    for (line = 0; line < len; line++)
        if (str[line] == chr) return line+1;
    for (int c = 0; c != chr && (c = fgetc(in)) != EOF; line++)
        inschrbuf(inbuf, c);
    return line;
}

char* center(char* text){
    size_t len = strlen(text);
    int max = width/2 + len/2; // excluding terminator
    int min = max-len+1; // first index of *text
    char* str = malloc(sizeof(char)*(max + 1));
    str[max] = 0;
    for (int i=0; i < min; i++) str[i] = ' ';
    memcpy(str+min, text, len);
    return str;
}

char* cmds[] = {"CT "};
char* (*call[])(char* txt) = {center};

char* cmd(void){
    char* dat = popstrbuf(inbuf, chrfill('\n'));
    size_t low = 0; size_t high = sizeof(cmds)/sizeof(*cmds); //len
    while (high >= low){
        int mid = ((unsigned int)low + (unsigned int)high) >> 1;
        char* mval = cmds[mid];

        int cmp = strncmp(dat, mval, strlen(mval));
        if (cmp < 0) // dat < mval
            low = mid + 1;
        else if (cmp > 0)
            high = mid - 1;
        else return call[mid](dat+strlen(mval));
    }
    return NULL;
}

char* typeset(void){
    return popstrbuf(inbuf, chrfill('\n'));
}

char* line(void){
    size_t sz;
    if ( (sz = fillbuf(2)) == 0)
        return "";
    char* twobytes = peekstrbuf(inbuf, 0, 2); // .., .\n, or ^.?
    if (sz == 1 || twobytes[1] == '\n') return typeset();
    if (twobytes[0] == '.') popchrbuf(inbuf);
    if (twobytes[0] == '.' && twobytes[1] != '.'){
        char* data = cmd();
        if (data) return data;
        return line();
    } else {
        return typeset();
    }
}

int main(int argc, char** argv){
    int c;
    in = getfile(argc, argv);
    inbuf = newbuf(256);
    if (in == NULL){
        perror(argv[1]);
        return 1;
    }
    char* out;
    while ( (out = line())[0] != '\0'){
        printf("%s",out);
    }
    fclose(in);
    return 0;
}