#include <stdio.h>
#include <stdlib.h>
#include <setjmp.h>

// TODO: handle conflicts (itemset_insert returns 2 on table problem)

#ifndef XCALLOC_IMPLEMENTED
#define XCALLOC_IMPLEMENTED
void *xcalloc(size_t n, size_t size) { void *addr = calloc(n, size); return addr ? addr : (exit(1), NULL); }
#else
extern void *xcalloc(size_t n, size_t size);
#endif

// Requirements
#include "parts/symbol.h"
#include "parts/grammar.h"
#include "parts/util-tables.h"

// Implements
#include "parts/table.h"

#define TABLE_CAP 64
static struct action *__table[TABLE_CAP];
struct action **table = __table;
size_t table_states = 0;

static jmp_buf fail_jmpbuf;

static void table_allocate() { for(size_t i = 0; i < TABLE_CAP; i++) table[i] = xcalloc(total_symbols, sizeof(*table[i])); }
static void table_deallocate() { for(size_t i = 0; i < TABLE_CAP; i++) free(table[i]); }
// static int table_insert(size_t state, symbol sym, struct action a); // in table.h

struct item {
    size_t prod_idx;
    size_t dot;
};

static int item_eq(struct item *i1, struct item *i2) { return (i1->dot == i2->dot && i1->prod_idx == i2->prod_idx) ? 1 : 0; }

#define SEEN_SETS_CAP 64
static struct {
    struct item *items;
    size_t nitems;
    size_t state;
} seen_sets[SEEN_SETS_CAP];
static size_t nseen_sets;

static void seen_sets_free() { for(size_t i = 0; i < nseen_sets; i++) free(seen_sets[i].items);}

static size_t itemset_handle(struct item *set, size_t nset);
static int itemset_insert(size_t state, struct item *initial_set, size_t ninitial);
static size_t itemset_closure(struct item *in_set, size_t nin, struct item *out_set, size_t nout);
static void itemset_print(struct item *set, size_t nset)
{
    printf("{");
    for(size_t i = 0; i < nset; i++)
        printf("{%zu, %zu}, ", set[i].prod_idx, set[i].dot);
    printf("}\n");
}

static size_t itemset_handle(struct item *set, size_t nset)
{
    // 1. is set in seen_sets
    for(size_t i = 0; i < nseen_sets; i++) {
        if(seen_sets[i].nitems != nset) continue;

        int _seen = 0;
        for(size_t j = 0; j < nset; j++) {
            _seen = 0;
            for(size_t k = 0; k < nset; k++)
                if(item_eq(&seen_sets[i].items[k], &set[j])) _seen = 1;
            if(!_seen) break;
        }
        if(_seen) return seen_sets[i].state;
    }

    // 2. add set to seen_sets
    if(nseen_sets >= SEEN_SETS_CAP) {
        fprintf(stderr, "ERROR: SEEN_SET_CAP exceeded\n");
        longjmp(fail_jmpbuf, 1);
    }

    seen_sets[nseen_sets].items = xcalloc(nset, sizeof(*set));
    seen_sets[nseen_sets].nitems = nset;
    for(size_t i = 0; i < nset; i++)
        seen_sets[nseen_sets].items[i] = set[i];

    // 3. insert new state
    size_t new_state = seen_sets[nseen_sets++].state = table_states++;
    if(new_state >= TABLE_CAP) {
        fprintf(stderr, "ERROR: TABLE_CAP exceeded\n");
        longjmp(fail_jmpbuf, 1);
    }

    if(itemset_insert(new_state, set, nset)) {
        fprintf(stderr, "ERROR: itemset_insert failed\n");
        longjmp(fail_jmpbuf, 1);
    }

    return new_state;
}

#define CLOSURE_SET_CAP 64
#define GOTO_SET_CAP 32
static int itemset_insert(size_t state, struct item *initial_set, size_t ninitial)
{
    struct item closure_set[CLOSURE_SET_CAP];

    size_t nclosure = itemset_closure(initial_set, ninitial, closure_set, CLOSURE_SET_CAP);
    if(nclosure > CLOSURE_SET_CAP) {
        fprintf(stderr, "ERROR: CLOSURE_SET_CAP exceeded\n");
        return 1;
    }

    for(size_t sym = 0; sym < total_symbols; sym++) {
        struct item goto_set[GOTO_SET_CAP];
        size_t ngoto = 0;

        for(size_t j = 0; j < nclosure; j++) {
            struct production *p = &grammar[closure_set[j].prod_idx];
            size_t dot = closure_set[j].dot;

            if(dot == p->nRHS) {
                if(!follow[p->LHS][sym]) continue;
                if(table_insert(state, sym, (struct action){
                            ACTION_REDUCE, closure_set[j].prod_idx}))
                    return 2;
                continue;
            }

            if(p->RHS[dot] == sym) {
                if(ngoto >= GOTO_SET_CAP) {
                    fprintf(stderr, "ERROR: GOTO_SET_CAP exceeded\n");
                    return 1;
                }
                goto_set[ngoto] = closure_set[j];
                goto_set[ngoto++].dot++;
            }
        }

        if(ngoto == 0) continue;

        if(symbol_is_input_end(sym)) {
            if(table_insert(state, sym, (struct action){ACTION_ACCEPT, 0}))
                return 2;
            continue;
        }

        size_t new_state = itemset_handle(goto_set, ngoto);

        if(table_insert(state, sym, (struct action){
                    symbol_is_terminal(sym) ? ACTION_SHIFT : ACTION_GOTO,
                    new_state})) return 2;
    }

    return 0;
}

static size_t itemset_closure(struct item *in_set, size_t nin, struct item *out_set, size_t nout_max)
{
    size_t nout = nin;

    if(nout > nout_max) return nout;
    for(size_t i = 0; i < nin; i++) out_set[i] = in_set[i];

    int *is_in_closure = xcalloc(total_productions, sizeof(int));
    for(size_t i = 0; i < nout; i++)
    {
        struct production *p = &grammar[out_set[i].prod_idx];
        if(out_set[i].dot == p->nRHS) continue;
        symbol sym = p->RHS[out_set[i].dot];

        for(size_t j = 0; j < total_productions; j++)
            if(grammar[j].LHS == sym) {
                if(is_in_closure[j]) continue;
                is_in_closure[j] = 1;

                if(nout++ >= nout_max) goto cleanup;
                out_set[nout-1] = (struct item){j, 0};
            }
    }

cleanup:
    free(is_in_closure);
    return nout;
}

IMPLEMENT_FUNCPTR(int, table_fill, ())
{
    table_allocate();

    int r = setjmp(fail_jmpbuf);
    if(r == 0) itemset_handle((struct item[]){{0, 0}}, 1);
    return r;
}

IMPLEMENT_FUNCPTR(void, table_free, ())
{
    seen_sets_free();
    table_deallocate();
}

#ifdef _SLR_TABLE_STANDALONE

// implement symbol.h
enum symbol {
    PLUS = 0,
    MINUS,
    LPAREN,
    RPAREN,
    N0, N1,
    END_INPUT,

    EP, E, T, N,
    SYMBOLS_END,
};

size_t total_symbols = SYMBOLS_END;

IMPLEMENT_FUNCPTR(int, symbol_is_terminal,  (symbol s)) { return s < EP; }
IMPLEMENT_FUNCPTR(int, symbol_is_input_end, (symbol s)) { return s == END_INPUT; }

// implement grammar.h
#define PROD(LHS, _, ...) {LHS, (symbol[]){__VA_ARGS__}, sizeof((symbol[]){__VA_ARGS__})/sizeof(symbol), 0}
static struct production _grammar[] = {
    PROD(EP, ->, E, END_INPUT),
    PROD(E, -->, E, PLUS, T),
    PROD(E, -->, E, MINUS, T),
    PROD(E, -->, T),
    PROD(T, -->, LPAREN, E, RPAREN),
    PROD(T, -->, N),
    PROD(N, -->, N0),
    PROD(N, -->, N1),
};

struct production *grammar = _grammar;
size_t total_productions = sizeof(_grammar)/sizeof(*_grammar);

// implement util-tables.h
#include "util-tables.c"

int main(void)
{
    int r = 0;

    util_tables_fill();
    if((r = table_fill())) goto cleanup;

    table_print();

cleanup:
    table_free();
    util_tables_free();
    return r;
}

#endif