/* manage.c -- what a node asks of whoever holds the fabric.  See manage.h.
 *
 * Nothing here uses the C library: the bare-metal kernel links this file.
 */
#include "v4/manage.h"

const char *const v4_manage_words[V4_MANAGE_WORDS] = {
    "NODE-ME", "NODE-BORN", "NODE-WIRE", "NODE-UNWIRE", "NODE-SLEEP", "NODE-WAKE", "NODE-KILL", "NODE-PARITY",
    "CAPSULE-OPEN", "CAPSULE-CELL", "CAPSULE-LINE", "NODE-CHILD", "NODE-PLACE"
};

/* A character of the node's memory: four to a cell, the first lowest, as
 * the system keeps text (capsules/v4/sys/core.f18). */
static int in_memory(v4_cell baddr) { return baddr >= 0 && (baddr >> 2) < (v4_cell)V4_NODE_WORDS; }
static char char_at(const v4_node *n, v4_cell baddr)
{
    return (char)(((v4_ucell)n->mem[baddr >> 2] >> (8 * (unsigned)(baddr & 3))) & 0xFFu);
}
static void char_put(v4_node *n, v4_cell baddr, char c)
{
    unsigned shift = 8 * (unsigned)(baddr & 3);
    v4_ucell cell = (v4_ucell)n->mem[baddr >> 2];
    cell = (cell & ~((v4_ucell)0xFFu << shift)) | ((v4_ucell)(unsigned char)c << shift);
    n->mem[baddr >> 2] = (v4_cell)cell;
}

static unsigned place_of(v4_cell x) { return x < 0 ? ~0u : (unsigned)x; }

static v4_manage_entry *by_number(const v4_manage *m, v4_cell number)
{
    unsigned k;
    if (number < 1) return 0;
    for (k = 0; k < m->reg_cap; k++) if (m->reg[k].number == number) return &m->reg[k];
    return 0;
}
static v4_manage_entry *by_place(const v4_manage *m, unsigned place)
{
    unsigned k;
    for (k = 0; k < m->reg_cap; k++) if (m->reg[k].number != 0 && m->reg[k].place == place) return &m->reg[k];
    return 0;
}
/* the place is the asker's own, or that of a node it birthed */
static int mine(const v4_manage *m, const v4_manage_entry *asker, unsigned place)
{
    const v4_manage_entry *e = by_place(m, place);
    return asker && e && (e == asker || e->parent == asker->number);
}
/* error 12 on the node that asked: a store to NODE-ERROR raises it (D-18) */
static int refuse(v4_node *n) { v4_node_store(n, n->error_reg, 12); return 1; }

int v4_manage_enter(const v4_manage *m, v4_cell number, unsigned place, v4_cell parent)
{
    unsigned k;
    if (number < 1 || by_number(m, number)) return 0;
    for (k = 0; k < m->reg_cap; k++) {
        if (m->reg[k].number == 0) {
            m->reg[k].number = number; m->reg[k].parent = parent; m->reg[k].place = place;
            return 1;
        }
    }
    return 0;
}

int v4_manage_serve(const v4_manage *m, unsigned place, v4_cell request)
{
    v4_fabric_node *at = v4_fabric_node_at(m->f, place);
    v4_manage_entry *me, *e;
    v4_node *n;
    v4_cell a, b, c, d;

    if (!at || request > V4_REQ_NODE_ME || request < V4_REQ_NODE_PLACE) return 0;
    n = &at->n;
    me = by_place(m, place);

    switch (request) {
    case V4_REQ_NODE_ME:                         /* ( -- place ) */
        v4_dstack_push(&n->ds, (v4_cell)place);
        return 1;
    case V4_REQ_NODE_BORN: {                     /* ( number -- place | -1 ) */
        int p;
        a = v4_dstack_pop(&n->ds);
        if (!me || a < 1 || by_number(m, a)) return refuse(n);
        p = m->born ? m->born(m->self) : -1;
        if (p >= 0 && !v4_manage_enter(m, a, (unsigned)p, me->number)) {   /* no room in the registry: the node goes again */
            v4_fabric_node *was = v4_fabric_remove(m->f, (unsigned)p);
            if (was && m->gone) m->gone(m->self, (unsigned)p, was);
            p = -1;
        }
        v4_dstack_push(&n->ds, (v4_cell)p);
        return 1;
    }
    case V4_REQ_NODE_WIRE:                       /* ( a pa b pb -- flag ) */
        d = v4_dstack_pop(&n->ds); c = v4_dstack_pop(&n->ds); b = v4_dstack_pop(&n->ds); a = v4_dstack_pop(&n->ds);
        if (!mine(m, me, place_of(a)) || !mine(m, me, place_of(c))) return refuse(n);
        v4_dstack_push(&n->ds, v4_fabric_wire(m->f, place_of(a), place_of(b), place_of(c), place_of(d)) ? -1 : 0);
        return 1;
    case V4_REQ_NODE_UNWIRE:                     /* ( a pa -- ) */
        b = v4_dstack_pop(&n->ds); a = v4_dstack_pop(&n->ds);
        if (!mine(m, me, place_of(a))) return refuse(n);
        (void)v4_fabric_unwire(m->f, place_of(a), place_of(b));
        return 1;
    case V4_REQ_NODE_SLEEP:                      /* ( number -- ) */
    case V4_REQ_NODE_WAKE:
    case V4_REQ_NODE_KILL:
        a = v4_dstack_pop(&n->ds);
        if (place != m->hera) return refuse(n);
        e = by_number(m, a);
        if (!e || e->place == place) return 1;   /* not live, or Hera herself: nothing */
        if (request == V4_REQ_NODE_SLEEP) v4_fabric_sleep(m->f, e->place);
        else if (request == V4_REQ_NODE_WAKE) v4_fabric_wake(m->f, e->place);
        else {
            unsigned gone_place = e->place;
            v4_fabric_node *was = v4_fabric_remove(m->f, gone_place);
            e->number = 0;
            if (was && m->gone) m->gone(m->self, gone_place, was);
        }
        return 1;
    case V4_REQ_NODE_PARITY: {                   /* ( place number -- ) */
        v4_fabric_node *it;
        b = v4_dstack_pop(&n->ds); a = v4_dstack_pop(&n->ds);
        e = by_place(m, place_of(a));
        if (!me || !e || e == me || e->parent != me->number || e->number != b) return refuse(n);
        it = v4_fabric_node_at(m->f, e->place);
        if (it && m->parity) m->parity(m->self, e->place, b, &it->n);
        return 1;
    }
    case V4_REQ_CAPSULE_OPEN: {                  /* ( baddr u -- flag ) */
        char name[64];
        unsigned i, len;
        b = v4_dstack_pop(&n->ds); a = v4_dstack_pop(&n->ds);
        if (!me) return refuse(n);
        len = b < 0 ? 0u : (unsigned)b;
        if (len == 0 || len > sizeof name || !in_memory(a) || !in_memory(a + (v4_cell)len - 1) || !m->open) {
            v4_dstack_push(&n->ds, 0);
            return 1;
        }
        for (i = 0; i < len; i++) name[i] = char_at(n, a + (v4_cell)i);
        v4_dstack_push(&n->ds, m->open(m->self, place, name, len) ? -1 : 0);
        return 1;
    }
    case V4_REQ_CAPSULE_CELL:                    /* ( -- w flag ) */
        if (!me) return refuse(n);
        a = 0;
        if (m->cell && m->cell(m->self, place, &a)) { v4_dstack_push(&n->ds, a); v4_dstack_push(&n->ds, -1); }
        else { v4_dstack_push(&n->ds, 0); v4_dstack_push(&n->ds, 0); }
        return 1;
    case V4_REQ_CAPSULE_LINE: {                  /* ( baddr -- u | -1 ) */
        char text[V4_MANAGE_LINE];
        int len, i;
        a = v4_dstack_pop(&n->ds);
        if (!me) return refuse(n);
        len = m->line ? m->line(m->self, place, text) : -1;
        if (len > V4_MANAGE_LINE) len = V4_MANAGE_LINE;
        if (len > 0 && (!in_memory(a) || !in_memory(a + len - 1))) len = -1;
        for (i = 0; i < len; i++) char_put(n, a + i, text[i]);
        v4_dstack_push(&n->ds, (v4_cell)len);
        return 1;
    }
    case V4_REQ_NODE_CHILD: {                    /* ( number i -- child | 0 ) */
        unsigned k;
        v4_cell found = 0;
        b = v4_dstack_pop(&n->ds); a = v4_dstack_pop(&n->ds);
        for (k = 0; k < m->reg_cap && !found; k++)
            if (m->reg[k].number != 0 && m->reg[k].parent == a && b-- == 0) found = m->reg[k].number;
        v4_dstack_push(&n->ds, found);
        return 1;
    }
    default:                                     /* V4_REQ_NODE_PLACE ( number -- place | -1 ) */
        a = v4_dstack_pop(&n->ds);
        e = by_number(m, a);
        v4_dstack_push(&n->ds, e ? (v4_cell)e->place : -1);
        return 1;
    }
}