#include "call.h"
#include "errloc.h"
#include "fn.h"
#include "lex.h"
#include "lit.h"
#include "parse.h"
#include "prv.h"
#include "stmt.h"
#include "type.h"
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static int callpr(const struct lex *l, struct prv *p);
static int callp(const struct lex *l, struct prv *p);
static int callr(const struct lex *l, struct prv *p);
static int callv(const struct lex *l, struct prv *p);

static const struct seq seqs[] =
{
    {(struct step[]){
        {ID},
        {ID, "using"},
        {ANY, NULL, 1},
        {ID, "returning"},
        {ID},
        {0}}, .fn = callpr},
    {(struct step[]){
        {ID},
        {ID, "using"},
        {ANY, NULL, 1},
        {0}}, .fn = callp},
    {(struct step[]){
        {ID},
        {ID, "returning"},
        {ID},
        {0}}, .fn = callr},
    {(struct step[]){
        {ID},
        {0}}, .fn = callv},
    {0}
};

static int param(const struct lex *l, struct prv *p, const struct tk *tk,
    struct call *c)
{
    const struct fn *fn = fn_cur(p);
    size_t n = c->nparams + 1;
    struct callparam *params;
    const struct lit *lit = NULL;
    const struct stentry *e = NULL;
    const struct type *t = NULL;
    int sign = 0;
    union callv u = {0};

    if (tk->type == LIT)
    {
        if (!(lit = lit_push(tk, p)))
            return -1;
    }
    else if (tk->type == NUM)
    {
        if ((sign = *tk->s == '-'))
            u.v = strtoll(tk->s, NULL, 0);
        else
            u.uv = strtoull(tk->s, NULL, 0);
    }
    else if ((t = type_find(fn, tk->s)))
    {
        if (t->type != C)
        {
            errloc(tk, "type \"%s\" not a constant", tk->s);
            return -1;
        }
    }
    else if (!(e = fn_var(fn, tk)))
    {
        errloc(tk, "undefined reference to parameter \"%s\"", tk->s);
        return -1;
    }

    if (!(params = realloc(c->params, n * sizeof *params)))
    {
        perror("realloc(3)");
        return -1;
    }

    c->params = params;
    c->params[c->nparams++] = (struct callparam)
    {
        .entry = e,
        .lit = lit,
        .t = t,
        .u = u
    };

    return 0;
}

static int callpr(const struct lex *l, struct prv *p)
{
    const struct tk *tk = p->stk + 2;
    struct call *c = &stmt_cur(p)->u.call;
    const struct pr *pr = c->pr;
    const struct stentry *e;
    size_t n = 0;

    while (!lex_eof(l, tk) && !kw((tk++)->s))
        n++;

    if (pr->variadic)
    {
        if (n < pr->nparams)
        {
            errloc(tk, "function \"%s\" expects at least %zu parameters, "
                "but %zu were given", c->tk->s, pr->nparams, n);
            return -1;
        }
    }
    else if (n != pr->nparams)
    {
        tk -= 2;
        errloc(tk, "function \"%s\" expects %zu parameters, "
            "but %zu were given", c->tk->s, pr->nparams, n);
        return -1;
    }
    else if (!pr->ret)
    {
        errloc(tk, "function \"%s\" does not expect any return variable",
            c->tk->s);
        return -1;
    }

    tk = p->stk + 2;

    for (size_t i = 0; i < n; i++)
        if (param(l, p, tk++, c))
            return -1;

    if (!(e = fn_var(fn_cur(p), ++tk)))
    {
        errloc(tk, "undefined reference to return variable \"%s\"",
            tk->s);
        return -1;
    }
    else if (pop(l, p))
        return -1;

    fprintf(stderr, "\t\tadding call to %s using %zu params "
        "and %s as return variable\n", c->tk->s, n, tk->s);
    c->ret = e;
    c->nparams = n;
    p->stk = ++tk;
    return 1;
}

static int callr(const struct lex *l, struct prv *p)
{
    const struct tk *tk = p->stk + 2;
    const struct fn *fn = fn_cur(p);
    const struct stentry *e;
    struct call *c = &stmt_cur(p)->u.call;
    const struct pr *pr = c->pr;

    if (!pr->ret)
    {
        errloc(tk, "function \"%s\" does not expect any return variable",
            c->tk->s);
        return -1;
    }
    else if (pr->nparams)
    {
        errloc(tk, "function \"%s\" expects %zu parameters, "
            "but none were given", c->tk->s, pr->nparams);
        return -1;
    }
    else if (!(e = fn_var(fn, tk)))
    {
        errloc(tk, "undefined reference to return variable \"%s\"",
            tk->s);
        return -1;
    }
    else if (pop(l, p))
        return -1;

    fprintf(stderr, "\t\tadding call to %s with %s as return variable\n",
        c->tk->s, tk->s);
    c->ret = e;
    p->stk = ++tk;
    return 1;
}

static int callp(const struct lex *l, struct prv *p)
{
    const struct tk *tk = p->stk + 2;
    struct call *c = &stmt_cur(p)->u.call;
    const struct pr *pr = c->pr;
    size_t n = 0;

    while (!lex_eof(l, tk) && !kw((tk++)->s))
        n++;

    if (pr->variadic)
    {
        if (n < pr->nparams)
        {
            errloc(tk, "function \"%s\" expects at least %zu parameters, "
                "but %zu were given", c->tk->s, pr->nparams, n);
            return -1;
        }
    }
    else if (pr->nparams != n)
    {
        errloc(tk, "function \"%s\" expects %zu parameters, "
            "but %zu were given", c->tk->s, pr->nparams, n);
        return -1;
    }

    tk = p->stk + 2;

    for (size_t i = 0; i < n; i++)
        if (param(l, p, tk++, c))
            return -1;

    if (pop(l, p))
        return -1;

    fprintf(stderr, "\t\tadding call to %s with 1 param\n", c->tk->s);
    p->stk = tk;
    return 1;
}

static int callv(const struct lex *l, struct prv *p)
{
    const struct tk *tk = p->stk;
    struct call *c = &stmt_cur(p)->u.call;
    const struct pr *pr = c->pr;

    if (pr->nparams)
    {
        errloc(tk, "function \"%s\" expects %zu parameters, "
            "but none were given", c->tk->s, pr->nparams);
        return -1;
    }
    else if (pop(l, p))
        return -1;

    fprintf(stderr, "\t\tadding call to %s with %s as return variable\n",
        c->tk->s, tk->s);
    p->stk = ++tk;
    return 1;
}

static const struct pr *find_proto(const struct fn *fn, const char *s)
{
    const struct type *t = type_find(fn, s);

    if (t && t->type == P)
        return t->u.p.fn->pr;

    return NULL;
}

static const struct pr *find(const struct ast *ast, const char *s)
{
    for (size_t i = 0; i < ast->nfns; i++)
    {
        const struct fn *fn = &ast->fns[i];
        const struct pr *pr;

        if ((pr = find_proto(fn, s)))
            return pr;
        else if (!strcmp(fn->tk->s, s))
            return fn->pr;
    }

    return NULL;
}

static int gettmp(char *tmp, size_t n)
{
    size_t j;

    for (j = 0; j < n; j++)
    {
        char c = tmp[j];

        if (!c)
            return tmp[j] = 'a';
        else if (c != 'z')
            return ++(tmp[j]);
    }

    return EOF;
}

static int param_lit(const struct lit *lit, struct cgen *c)
{
    printf("l $%s", lit->name);
    return 0;
}

static int param_id(const struct stentry *e, struct cgen *c, char *tmp,
    size_t n)
{
    const char *name = e->tk->s;
    const struct type *t = e->t;

    printf("%s ", cgen_sz(t->sz));

    if (cgen_global(c->fn, e))
        printf("$%s", name);
    else if (cgen_abity(t))
    {
        if (gettmp(tmp, n) == EOF)
            return -1;

        printf("%%%s", tmp);
    }
    else
        printf("%%%s_", name);

    return 0;
}

static int param_c(const struct type *t, struct cgen *cg)
{
    const union c *c = &t->u.c;

    /* TODO: adapt type to expected param size */
    fputs("l ", stdout);

    if (t->sign)
        printf("%lld", c->v);
    else
        printf("%llu", c->uv);

    return 0;
}

static int param_num(const struct callparam *cp, struct cgen *c)
{
    const union callv *u = &cp->u;

    /* TODO: adapt type to expected param size */
    fputs("w ", stdout);

    if (cp->sign)
        printf("%lld", u->v);
    else
        printf("%llu", u->uv);

    return 0;
}

static int param_load(const struct call *m, struct cgen *c)
{
    char tmp[sizeof "abcdefghijklmnopqrstuvwxyz"] = {0};

    for (size_t i = 0; i < m->nparams; i++)
    {
        const struct callparam *cp = &m->params[i];
        const struct stentry *e = cp->entry;

        if (!e || cgen_global(c->fn, e) || !cgen_abity(e->t))
            continue;
        else if (gettmp(tmp, sizeof tmp - 1) == EOF)
        {
            fprintf(stderr, "%s: exhausted temporaries\n", __func__);
            return -1;
        }

        printf("%%%s =%s load%s %%%s_\n", tmp, cgen_sz(e->t->sz),
            cgen_load(e->t), e->tk->s);
    }

    return 0;
}

int call_cgen(const struct call *m, struct cgen *c)
{
    char tmps[sizeof "abcdefghijklmnopqrstuvwxyz"] = {0};
    const struct stentry *ret = m->ret;
    const char *tmp;
    size_t sz;

    if (param_load(m, c))
        return -1;
    else if (ret)
    {
        tmp = cgen_tmp((sz = ret->t->sz));
        printf("%%%s =%s ", tmp, cgen_sz(sz));
    }

    printf("call $%s(", m->tk->s);

    for (size_t i = 0; i < m->nparams; i++)
    {
        const struct callparam *cp = &m->params[i];
        int var = m->pr->variadic;

        if (cp->lit)
            param_lit(cp->lit, c);
        else if (cp->entry)
            param_id(cp->entry, c, tmps, sizeof tmps - 1);
        else if (cp->t)
            param_c(cp->t, c);
        else
            param_num(cp, c);

        if (var && i + 1 == var - 1)
            fputs(", ...", stdout);

        if (i + 1 < m->nparams)
            fputs(", ", stdout);
    }

    puts(")");

    if (ret)
    {
        const char *name = ret->tk->s;

        printf("store%s %%%s, ", cgen_sz(sz), tmp);

        if (cgen_global(c->fn, ret))
            printf("%s", name);
        else
            printf("%%%s_", name);

        putchar('\n');
    }

    return 0;
}

void call_free(struct call *c)
{
    if (c)
        free(c->params);
}

int call(const struct lex *l, struct prv *p)
{
    const struct tk *tk = p->tk;
    const struct pr *pr;
    struct fn *fn = fn_cur(p);
    size_t n = fn->nstmts +1;
    struct stmt *stmts;
    struct pos init =
    {
        .seq = seqs,
        .stseq = seqs,
        .step = seqs->steps
    };

    /* TODO: function pointers */

    if (lex_eof(l, tk))
    {
        errloc(tk - 1, "incomplete call statement");
        return -1;
    }
    else if (!(pr = find(p->ast, tk->s)))
    {
        errloc(tk, "undefined reference to function \"%s\"", tk->s);
        return -1;
    }
    else if (!(stmts = realloc(fn->stmts, n * sizeof *stmts)))
    {
        perror("realloc(3)");
        return -1;
    }

    fn->stmts = stmts;
    fn->stmts[fn->nstmts++] = (struct stmt)
    {
        .type = CALL,
        .u.call =
        {
            .tk = tk,
            .pr = pr
        }
    };

    if (push(&init, p))
        return -1;

    p->stk = p->tk;
    return 1;
}