#include "from.h"
#include "cgen.h"
#include "fn.h"
#include "errloc.h"
#include "stmt.h"
#include "storage.h"
#include "tmp.h"
#include "type.h"
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void from_free(struct from *fr)
{
}

static int loadvar(const struct from_it *st, struct cgen *c)
{
    const struct stentry *e = st->u.e;
    size_t sz = e->t->sz;
    const char *tmp = cgen_tmp(sz);

    printf("%%%s =%s load%s ", tmp, cgen_sz(sz), cgen_load(e->t));
    cgen_printvar(c->fn, e);
    putchar('\n');
    return 0;
}

/* TODO: de-duplicate function */
static unsigned long long tonum(const char *s)
{
    unsigned long long v;
    char *end;

    errno = 0;
    v = strtoull(s, &end, 0);

    if (*s == '-' || errno || *end)
        return strtoll(s, NULL, 0);

    return v;
}

static int loadval(const struct from *fr, struct cgen *c)
{
    const struct stentry *dst = fr->var;
    const struct from_it *st = &fr->start;
    unsigned long long v = tonum(st->u.tk->s);

    printf("store%s %llu, ", cgen_sz(dst->t->sz), v);
    cgen_printvar(c->fn, dst);
    putchar('\n');
    return 0;
}

static int endvar(const struct from *fr, struct cgen *c)
{
    fprintf(stderr, "%s: TODO\n", __func__);
    return -1;
}

static int endval(const struct from *fr, struct cgen *c)
{
    const struct stentry *src = fr->var;
    size_t sz = src->t->sz;
    const char *tmp = cgen_tmp(sz);
    const struct from_it *end = &fr->end;
    const struct tk *tk = end->u.tk;
    int neg = *tk->s == '-';
    size_t bl = fr->block_i;

    printf("%%%s =%s load%s ", tmp, cgen_sz(sz), cgen_load(src->t));
    cgen_printvar(c->fn, src);
    putchar('\n');
    printf("%%%s =%s c", tmp, cgen_sz(sz));
    fputs(neg ? "sge" : "uge", stdout);
    printf("%s ", cgen_sz(sz));
    printf("%%%s, %s\n", tmp, tk->s);
    printf("jnz %%%s, @__end%zu, @__blockbody%zu\n", tmp, bl, bl);
    printf("@__blockbody%zu\n", bl);
    return 0;
}

static int from_var(const struct from *fr, struct cgen *c)
{
    const struct from_it *st = &fr->start;

    switch (st->type)
    {
    case FR_VAR:
        if (loadvar(st, c))
            return -1;
        break;

    case FR_VAL:
        if (loadval(fr, c))
            return -1;
        break;
    }

    printf("@__block%zu\n", fr->block_i);

    switch (fr->end.type)
    {
    case FR_VAR:
        if (endvar(fr, c))
            return -1;
        break;

    case FR_VAL:
        if (endval(fr, c))
            return -1;
        break;
    }

    return 0;
}

int from_cgen(const struct from *fr, struct cgen *c)
{
    return from_var(fr, c);
}

static int from_end(const struct stmt *s, struct cgen *c)
{
    const struct from *fr = &s->u.from;
    const struct stentry *src = fr->var;
    const struct type *t = src->t;
    size_t sz = t->sz;
    const char *tmp = cgen_tmp(sz);
    const struct fn *fn = c->fn;

    printf("%%%s =%s load%s ", tmp, cgen_sz(sz), cgen_load(t));
    cgen_printvar(fn, src);
    putchar('\n');
    printf("%%%s =%s add %%%s, 1\n", tmp, cgen_sz(sz), tmp);
    printf("store%s %%%s, ", cgen_sz(sz), tmp);
    cgen_printvar(fn, src);
    putchar('\n');
    printf("jmp @__block%zu\n", fr->block_i);
    return 0;
}

static int checksym(const struct fn *fn, const struct tk *tk,
    struct from_it *fr)
{
    const struct stentry *e = fn_var(fn, tk);

    if (!e)
    {
        errloc(tk, "undefined reference to \"%s\"", tk->s);
        return -1;
    }

    switch (e->t->type)
    {
    case C:
    case BUILTIN:
        break;
    case U:
    case S:
    case P:
    case T:
    case PTR:
    case ARY:
    {
        char *s = type_name(e->t);

        if (s)
            errloc(tk, "\"%s\" (\"%s\") cannot be used in \"from\" loop",
                tk->s, s);

        free(s);
        return -1;
    }
    }

    fr->type = FR_VAR;
    fr->u.e = e;
    return 0;
}

static int check(const struct fn *fn, const struct tk *tk, struct from_it *fr)
{
    switch (tk->type)
    {
    case NUM:
        fr->type = FR_VAL;
        fr->u.tk = tk;
        break;
    case ID:
        return checksym(fn, tk, fr);
    case LIT:
        errloc(tk, "unexpected literal");
        return -1;
    case UNDEF:
    case ANY:
        fprintf(stderr, "%s: unreachable\n", __func__);
        return -1;
    }

    return 0;
}

static int finalize(struct prv *p, struct fn *fn, struct from *fr)
{
    struct stmt *s;
    struct pos *pos = &p->pos[p->i];
    size_t nst = fn->nstmts + 1, nbl = fn->nblocks + 1,
        *bl = realloc(fn->blocks, nbl * sizeof *bl);

    if (!bl)
    {
        perror("realloc(3)");
        return -1;
    }

    fr->block_i = bl[fn->nblocks++] = fn->nstmts;
    fn->blocks = bl;

    if (!(s = realloc(fn->stmts, nst * sizeof *s)))
    {
        perror("realloc(3)");
        return -1;
    }

    s[fn->nstmts++] = (struct stmt)
    {
        .type = FROM,
        .u.from = *fr,
        .end = from_end
    };

    fn->stmts = s;
    pos->seq = pos->stseq = stmts;
    pos->step = stmts->steps;
    fprintf(stderr, ", iterator %s, block index %zu\n", fr->var->tk->s,
        bl[fn->nblocks - 1]);
    return 0;
}

static const struct type *valtype(const struct fn *fn, const struct tk *tk)
{
    char *end;

    errno = 0;
    strtol(tk->s, &end, 0);

    if (errno || *end)
    {
        errno = 0;
        strtoll(tk->s, &end, 0);

        if (errno || *end)
            return type_find(fn, "ulong");

        return type_find(fn, "long");
    }

    return type_find(fn, "word");
}

static const struct type *ittype(const struct fn *fn, const struct from_it *it)
{
    switch (it->type)
    {
    case FR_VAL:
        return valtype(fn, it->u.tk);
    case FR_VAR:
        return it->u.e->t;
    }

    fprintf(stderr, "%s: unreachable\n", __func__);
    return NULL;
}

static const struct type *gettype(const struct fn *fn,
    const struct from_it *a, const struct from_it *b)
{
    const struct type *ta = ittype(fn, a), *tb = ittype(fn, b);

    return ta->sz > tb->sz ? ta : tb;
}

int from(const struct lex *l, struct prv *p)
{
    const struct tk *start = p->stk + 1, *end = p->stk + 3;
    struct fn *fn = fn_cur(p);
    struct from fr = {0};
    const struct type *t;

    if (check(fn, start, &fr.start)
        || check(fn, end, &fr.end)
        || !(t = gettype(fn, &fr.start, &fr.end))
        || !(fr.var = tmp_create(fn, t)))
        return -1;

    fprintf(stderr, "\t\tadding from statement [%s, %s]", start->s, end->s);

    if (finalize(p, fn, &fr))
        return -1;

    p->stk = ++end;
    return 1;
}

static int checkvar(const struct fn *fn, const struct tk *tk, struct from *fr)
{
    const struct stentry *e;

    if (tk->type != ID)
    {
        errloc(tk, "\"%s\" not a variable", tk->s);
        return -1;
    }
    else if (!(e = fn_var(fn, tk)))
    {
        errloc(tk, "undefined reference to \"%s\"", tk->s);
        return -1;
    }
    else if (e->t->type != BUILTIN)
    {
        errloc(tk, "variable \"%s\" not an integer", tk->s);
        return -1;
    }

    fr->var = e;
    return 0;
}

int from_id(const struct lex *l, struct prv *p)
{
    const struct tk *start = p->stk + 1, *end = p->stk + 3, *var = p->stk + 5;
    struct fn *fn = fn_cur(p);
    struct from fr = {0};

    if (check(fn, start, &fr.start)
        || check(fn, end, &fr.end)
        || checkvar(fn, var, &fr))
        return -1;

    fprintf(stderr, "\t\tadding from statement [%s, %s] using %s",
        start->s, end->s, var->s);

    if (finalize(p, fn, &fr))
        return -1;

    p->stk = ++var;
    return 1;
}

int from_by(const struct lex *l, struct prv *p)
{
    fprintf(stderr, "%s: TODO\n", __func__);
    return -1;
}

int from_idby(const struct lex *l, struct prv *p)
{
    fprintf(stderr, "%s: TODO\n", __func__);
    return -1;
}