#include "world.hpp"
#include "pprint.hpp"
#include <cmath>
#include <iostream>

static void tangible_getall(LuaStack &LS0, LuaSlot list, const util::IdVector &idv) {
    LuaVar tangibles, tan;
    LuaStack LS(LS0.state(), tangibles, tan);
    LS.rawget(tangibles, LuaRegistry, "tangibles");
    assert(LS.istable(tangibles));
    LS.set(list, LuaNewTable);
    int index = 1;
    for (int64_t id : idv) {
        LS.rawget(tan, tangibles, id);
        assert(LS.istable(tan));
        LS.rawset(list, index++, tan);
    }
    LS.result();
}

LuaDefine(tangible_animstate, "tan", 
    "|Get the entire animation state of the tangible."
    "|Returns six values: graphic,plane,x,y,z,facing.") {
    LuaArg tanobj;
    LuaRet graphic, plane, x, y, z, facing;
    LuaStack LS(L, tanobj, graphic, plane, x, y, z, facing);
    World *w = World::fetch_global_pointer(L);
    Tangible *tan = w->tangible_get(LS, tanobj);
    const AnimStep &aqback = tan->anim_queue_.back();
    LS.set(graphic, aqback.graphic());
    LS.set(plane, aqback.plane());
    LS.set(x, aqback.xyz().x);
    LS.set(y, aqback.xyz().y);
    LS.set(z, aqback.xyz().z);
    LS.set(facing, aqback.facing());
    return LS.result();
}

LuaDefine(tangible_xyz, "tan", 
    "|Get the current coordinates of the tangible."
    "|Returns three values: x, y, z") {
    LuaArg tanobj;
    LuaRet x, y, z;
    LuaStack LS(L, tanobj, x, y, z);
    World *w = World::fetch_global_pointer(L);
    Tangible *tan = w->tangible_get(LS, tanobj);
    const AnimStep &aqback = tan->anim_queue_.back();
    LS.set(x, aqback.xyz().x);
    LS.set(y, aqback.xyz().y);
    LS.set(z, aqback.xyz().z);
    return LS.result();
}

LuaDefine(tangible_animate, "tan,configtable",
    "|Add an animation step to the tangible."
    "|The configtable is a table containing any of the following:"
    "|action,graphic,plane,x,y,z,facing") {
    LuaArg tanobj, config;
    LuaStack LS(L, tanobj, config);
    World *w = World::fetch_global_pointer(L);
    Tangible *tan = w->tangible_get(LS, tanobj);
    int64_t id = w->alloc_id_predictable();
    const AnimStep &prev = tan->anim_queue_.back();
    AnimStep step;
    step.from_lua(L, config.index(), false, prev);
    if (step.action() == "") {
        luaL_error(L, "animation action must be specified");
    }
    tan->anim_queue_.add(id, step);
    tan->update_plane_item();
    return LS.result();
}

LuaDefine(tangible_setclass, "tan,class",
    "|Set the class of the tangible."
    "|The class can be a 'class table' (ie, a table of methods), "
    "|or it can be a string that names a class.  The tangible is "
    "|given an __index metamethod that points at the class table.") {
    LuaArg tanobj, classname;
    LuaVar classtab, mt;
    LuaStack LS(L, tanobj, classname, classtab, mt);
    World *w = World::fetch_global_pointer(L);
    w->tangible_get(LS, tanobj);
    eng::string err = LS.getclass(classtab, classname);
    if (err != "") {
        luaL_error(L, "%s", err.c_str());
    }
    LS.getmetatable(mt, tanobj);
    LS.rawset(mt, "__index", classtab);
    return LS.result();
}

LuaDefine(tangible_getclass, "tan", 
    "|Get the class of the tangible, if any."
    "|The return value is a string, the class name, not"
    "|the class table.") {
    LuaArg tanobj;
    LuaVar mt, classtab;
    LuaRet classname;
    LuaStack LS(L, tanobj, mt, classtab, classname);
    World *w = World::fetch_global_pointer(L);
    w->tangible_get(LS, tanobj);
    LS.getmetatable(mt, tanobj);
    LS.rawget(classtab, mt, "__index");
    eng::string name = LS.classname(classtab);
    if (name == "") {
        LS.set(classname, LuaNil);
    } else {
        LS.set(classname, name);
    }
    return LS.result();
}

LuaDefine(tangible_delete, "tan", 
    "|Delete the specified tangible."
    "|This cannot be used to delete player tangibles,"
    "|To delete a player, use tangible.redirect") {
    LuaArg tanobj;
    LuaStack LS(L, tanobj);
    World *w = World::fetch_global_pointer(L);
    Tangible *tan = w->tangible_get(LS, tanobj);
    assert(tan != nullptr); // this should be checked above.
    if (tan->is_an_actor()) {
        luaL_error(L, "Cannot delete a player using tangible.delete, use tangible.redirect instead.");
        return 0;
    }
    w->tangible_delete(tan->id());
    return LS.result();
}

LuaDefine(tangible_build, "configtable", 
    "|Build a new tangible object."
    "|The configtable must contain: class,x,y,z,plane,graphic."
    "|The configtable can optionally contain: facing.") {
    LuaArg config;
    LuaVar classname, classtab, mt;
    LuaRet database;
    LuaStack LS(L, config, classname, classtab, database, mt);
    
    LS.checktable(config, "config");
    // Get the class of the new tangible.
    LS.rawget(classname, config, "class");
    eng::string err = LS.getclass(classtab, classname);
    if (err != "") {
        luaL_error(L, "%s", err.c_str());
    }

    // Parse the initial animation step.
    AnimStep initstep, blank;
    initstep.from_lua(L, config.index(), true, blank);
    if (!initstep.has_xyz()) {
        luaL_error(L, "You must specify (X,Y,Z) for new tangible");
    }
    if (!initstep.has_plane()) {
        luaL_error(L, "You must specify plane for new tangible");
    }
    if (!initstep.has_graphic()) {
        luaL_error(L, "You must specify graphic for new tangible");
    }

    // TODO: generate error if there's extra crap in the config table.

    World *w = World::fetch_global_pointer(L);
    int64_t new_id = w->alloc_id_predictable();
    Tangible *tan = w->tangible_make(L, new_id, "nowhere", true);
    lua_replace(L, database.index());

    // Update the class of the new tangible.
    LS.getmetatable(mt, database);
    LS.rawset(mt, "__index", classtab);

    // Update the animation queue and planemap of the new tangible.
    int64_t stepid = w->alloc_id_predictable();
    tan->anim_queue_.add(stepid, initstep);
    tan->update_plane_item();

    return LS.result();
}

LuaDefine(tangible_get, "id", 
    "|Get the tangible with the specified id."
    "|This is for debugging only and will be removed in"
    "|the released version.") {
    LuaArg id;
    LuaVar tangibles;
    LuaRet database;
    LuaStack LS(L, id, tangibles, database);
    int64_t nid = LS.ckinteger(id);
    LS.rawget(tangibles, LuaRegistry, "tangibles");
    LS.rawget(database, tangibles, id);
    if (!LS.istable(database)) {
        luaL_error(L, "Not a tangible ID: %d", nid);
    }
    return LS.result();
}

LuaDefine(tangible_redirect, "tan1,tan2,bulldozetan1", 
    "|Redirect is not working yet") {
    LuaArg actor1, actor2, bldz;
    LuaStack LS(L, actor1, actor2, bldz);
    World *w = World::fetch_global_pointer(L);
    bool bulldoze = LS.ckboolean(bldz);
    Tangible *tan1 = w->tangible_get(LS, actor1);
    if (!tan1->is_an_actor()) {
        luaL_error(L, "redirect source is not an actor");
    }
    if (LS.isnil(actor2)) {
        w->redirects_[tan1->id()] = 0;
    } else {
        Tangible *tan2 = w->tangible_get(LS, actor2);
        tan2->configure_id_pool_for_actor();
        w->redirects_[tan1->id()] = tan2->id();
    }
    if (bulldoze) {
        w->tangible_delete(tan1->id());
    }
    return LS.result();
}

LuaDefine(tangible_id, "tan",
    "|Return the tangible's id number."
    "|This is for debugging only and will be removed"
    "|in the released version.") {
    LuaArg tanobj;
    LuaRet id;
    LuaStack LS(L, tanobj, id);
    int64_t tid = LS.tanid(tanobj);
    if (tid == 0) {
        luaL_error(L, "Not a tangible");
    }
    LS.set(id, tid);
    return LS.result();
}

LuaDefine(tangible_actor, "",
    "|Return the current actor.") {
    LuaRet actor;
    LuaVar tangibles;
    LuaStack LS(L, tangibles, actor);
    World *w = World::fetch_global_pointer(L);
    LS.rawget(tangibles, LuaRegistry, "tangibles");
    LS.rawget(actor, tangibles, w->lthread_actor_id_);
    return LS.result();
}

LuaDefine(tangible_place, "",
    "|Return the current place.") {
    LuaRet place;
    LuaVar tangibles;
    LuaStack LS(L, tangibles, place);
    World *w = World::fetch_global_pointer(L);
    LS.rawget(tangibles, LuaRegistry, "tangibles");
    LS.rawget(place, tangibles, w->lthread_place_id_);
    return LS.result();
}

LuaDefine(tangible_near, "tan,radius,omit_nowhere,omit_self",
    "|Scan near the specified tangible."
    "|If omit_nowhere is true, and the tangible is on the nowhere plane,"
    "|then the scan returns empty.  If omit_self is true, then the "
    "|tangible passed in is omitted from the results.") {
    LuaArg ltan, lradius, lomit_nowhere, lomit_self;
    LuaRet list;
    LuaStack LS(L, ltan, lradius, lomit_nowhere, lomit_self, list);
    World *w = World::fetch_global_pointer(L);
    Tangible *tan = w->tangible_get(LS, ltan);
    const AnimStep &aqback = tan->anim_queue_.back();

    PlaneScan scan;
    scan.set_plane(aqback.plane());
    scan.set_bbox_given_center_radius(aqback.xyz(), LS.cknumber(lradius));
    scan.set_shape(PlaneScan::SPHERE);
    scan.set_sorted(true);
    scan.set_near(tan->id(), !LS.ckboolean(lomit_self));
    scan.set_omit_nowhere(LS.ckboolean(lomit_nowhere));
    
    util::IdVector idv = w->plane_map_.scan(scan);
    tangible_getall(LS, list, idv);
    return LS.result();
}

LuaDefine(tangible_scan, "plane,x,y,radius,omit_nowhere",
    "|Scan the specified plane."
    "|If omit_nowhere is true, and the plane is 'nowhere', then"
    "|the scan returns empty.") {
    LuaArg lplane, lx, ly, lradius, lomit_nowhere;
    LuaRet list;
    LuaStack LS(L, lplane, lx, ly, lradius, lomit_nowhere, list);
    World *w = World::fetch_global_pointer(L);

    PlaneScan scan;
    scan.set_plane(LS.ckstring(lplane));
    scan.set_bbox_given_center_radius(util::XYZ(LS.cknumber(lx), LS.cknumber(ly), 0), LS.cknumber(lradius));
    scan.set_shape(PlaneScan::SPHERE);
    scan.set_sorted(true);
    scan.set_omit_nowhere(LS.ckboolean(lomit_nowhere));

    util::IdVector idv = w->plane_map_.scan(scan);
    tangible_getall(LS, list, idv);
    return LS.result();
}

LuaDefine(tangible_find, "config",
    "|Find tangibles by their location."
    "|"
    "|There are multiple ways to specify the plane, the bounding"
    "|box, and the shape of the search.  The most basic is to"
    "|include these parameters in the table:"
    "|"
    "|   plane    : the plane to search (a string)"
    "|   centerx  : x-coordinate of the center of the search"
    "|   centery  : y-coordinate of the center of the search"
    "|   centerz  : z-coordinate of the center of the search"
    "|   radius   : the radius of the search"
    "|   shape    : 'box', 'sphere', or 'cylinder'"
    "|"
    "|Shape has a default: 'sphere'.  The other parameters do"
    "|not have default values."
    "|"
    "|Instead of specifying the radius as a single float,"
    "|you may optionally specify separate radii for each dimension."
    "|"
    "|   radiusx  : the radius in the x-dimension."
    "|   radiusy  : the radius in the y-dimension."
    "|   radiusz  : the radius in the z-dimension."
    "|"
    "|If you specify different radii in each dimension, then the"
    "|'sphere' shape will actually be a spheroid, and the 'cylinder'"
    "|shape will actually be a cylindroid."
    "|"
    "|Instead of specifying the center and plane, you can specify"
    "|a tangible to search near:"
    "|"
    "|   near     : a tangible in whose vicinity the search occurs"
    "|"
    "|If you specify 'near', then by default, the near tangible is"
    "|filtered out of the search.  If you want to include it in the"
    "|results, set the 'include' flag to true.  In this case, the"
    "|near tangible will always be the first search result:"
    "|"
    "|   include  : include the 'near' object in the results"
    "|"
    "|If you want to search an entire plane, you can use the"
    "|wholeplane option, which replaces all the other options:"
    "|"
    "|   wholeplane: the name of the plane to scan in its entirety"
    "|"
    "|It is valid to use 0.0 as a radius.  For example, you could"
    "|use shape='cylinder' and radiusz=0.0 to scan a flat"
    "|circular area."
    "|"
    "|It is also valid to use math.huge (infinity) as a radius.  For"
    "|example, you could use shape='cylinder' and radiusz=math.huge"
    "|to scan an infinitely tall cylinder."
    "|"
    "|If you are making a 2D game, it works fine to set all object Z"
    "|coordinates to zero, and then do searches with centerz=0.0"
    "|and radiusz=0.0."
    "|") {
    LuaArg config;
    LuaRet result;
    LuaStack LS(L, config, result);
    LuaKeywordParser kw(LS, config);
    PlaneScan scan;
    scan.configure(kw);
    kw.check_unparsed_keywords();

    // When the configure routine sees the 'near' flag, it stores the tangible
    // ID, but not the center and plane, because doing so would require it to
    // know about world models.  We have to handle center and plane for 'near'
    // separately.
    World *w = World::fetch_global_pointer(L);
    int64_t near = scan.near();
    if (near != 0) {
        Tangible *t = w->tangible_get(near);
        assert(t != nullptr); // Should never happen.
        const AnimStep &aqback = t->anim_queue_.back();
        scan.set_plane(aqback.plane());
        scan.set_center(aqback.xyz());
    }
    // Do the scan.
    util::IdVector idv = w->plane_map_.scan(scan);
    tangible_getall(LS, result, idv);
    return LS.result();
}

LuaDefine(tangible_start, "tangible,function,arg1,arg2...",
    "|Start a thread."
    "|"
    "|Every thread is owned by a tangible.  The first argument"
    "|to 'tangible.start' indicates the tangible that owns"
    "|the new thread.  Instead of passing a single tangible,"
    "|you can pass a list of tangibles, in which case a thread"
    "|is started on each tangible."
    "|"
    "|The function can be a lua closure, or it can be a string."
    "|If it's a string, then the tangible's class will be"
    "|used to look up the relevant closure."
    "|"
    "|The arguments arg1,arg2... will be passed to the"
    "|function."
    "|"
    "|Actor and place aren't passed to the function unless"
    "|you manually include them in the list arg1, arg2, etc."
    "|The new thread can, however, use the builtin "
    "|functions 'tangible.actor' and 'tangible.place' to obtain "
    "|actor and place.  Actor will be the same actor who "
    "|called 'tangible.start'.  Place will be the tangible that"
    "|owns the thread, ie, the tangible passed to 'tangible.start'."
    "|"
    "|The new thread doesn't start running instantly:"
    "|it waits until the current thread is finished.  The"
    "|current thread must either block (eg, 'wait') or terminate"
    "|before the new thread can actually begin execution."
    "|"
    "|If you start a thread, then start another, then both of"
    "|the newly-started threads wait until the current thread"
    "|is finished.  At that point, it is undefined which of the"
    "|two new threads runs first."
    "|"
    "|Threads are owned by tangibles.  If a tangible is"
    "|deleted, then none of its threads will ever be resumed,"
    "|for any reason."
    "|"
    "|However, if a thread deletes its own place (ie, the tangible"
    "|that owns the thread), then the thread will be allowed"
    "|to continue running until it blocks. But from that point"
    "|forward, the thread will never be resumed for any reason.") {

    int top = lua_gettop(L);
    if (top < 2) {
        luaL_error(L, "Not enough arguments to tangible.start");
        return 0;
    }
    int varlen = top - 2;

    World *w = World::fetch_global_pointer(L);
    w->guard_blockable(L, "tangible.start");

    LuaVar mt, classtab, plthreads, thread, thinfo, func, tanlist;
    LuaStack LS(L, mt, classtab, plthreads, thread, thinfo, func, tanlist);
    LuaSpecial place(1);
    LuaSpecial fname(2);

    // If they passed in a single tangible, convert it to a tangible list.
    int64_t place_id = LS.tanid(place);
    if (place_id != 0) {
        LS.newtable(tanlist);
        LS.rawset(tanlist, 1, place);
    } else {
        LS.set(tanlist, place);
        if (!LS.istable(tanlist)) {
            luaL_error(L, "tangible.start expects a tangible or list of tangibles");
            return 0;
        }
    }

    for (int i = 1; ; i++) {
        LS.rawget(place, tanlist, i);
        if (LS.isnil(place)) break;

        // Confirm that the place is a valid tangible,
        // and get the tangible ID.
        w->tangible_get(LS, place);
        place_id = LS.tanid(place);

        // Get place's metatable and threads table.
        LS.getmetatable(mt, place);
        assert(LS.istable(mt));
        LS.rawget(plthreads, mt, "threads");
        assert(LS.istable(plthreads));

        // Get the function closure.
        if (LS.isfunction(fname)) {
            LS.set(func, fname);
        } else if (LS.isstring(fname)) {
            LS.rawget(classtab, mt, "__index");
            assert(LS.istable(classtab));
            LS.rawget(func, classtab, fname);
            if (!LS.isfunction(func)) {
                eng::string cfname = LS.ckstring(fname);
                luaL_error(L, "tangible doesn't have method: %s", cfname.c_str());
                return 0;
            }
        } else {
            luaL_error(L, "invalid function, expected closure or string");
            return 0;
        }

        // Create a new thread, set up function and arguments.
        lua_State *CO = LS.newthread(thread);
        lua_pushvalue(L, func.index());
        for (int i = 0; i < varlen; i++) {
            lua_pushvalue(L, i + 3);
        }
        lua_xmove(L, CO, varlen + 1);
    
        // Create the thread info table.
        LS.newtable(thinfo);
        LS.rawset(thinfo, "thread", thread);
        LS.rawset(thinfo, "actorid", w->lthread_actor_id_);
        LS.rawset(thinfo, "isnew", true);
        LS.rawset(thinfo, "useppool", false);
        LS.rawset(thinfo, "print", false);
    
        // Get a thread ID for the new thread, store it in
        // the thread table.  
        int64_t tid = w->alloc_id_predictable();
        LS.rawset(plthreads, tid, thinfo);
    
        // Push the thread's ID into the runnable thread queue.
        w->schedule(0, tid, place_id);
    }
    return LS.result();
}


LuaDefine(wait, "nticks",
    "|Wait the specified number of ticks.") {
    World *w = World::fetch_global_pointer(L);
    w->guard_blockable(L, "wait");

    // Parse the argument.
    LuaArg seconds;
    LuaStack LS(L, seconds);
    int64_t n = LS.ckinteger(seconds);
    if ((n < 0) || (n > 1000000)) {
        luaL_error(L, "Argument to wait must be between 0 and 1000000");
        return LS.result();
    }

    // Schedule a continuation.
    w->schedule(w->clock_ + n, w->lthread_thread_id_, w->lthread_place_id_);
    return lua_yield(L, 0);
}

LuaDefine(nopredict, "",
    "|Stop predictive execution of this thread.") {
    World *w = World::fetch_global_pointer(L);
    w->guard_nopredict(L, "nopredict");

    if (lua_gettop(L) != 0) {
        luaL_error(L, "nopredict takes no arguments");
    }
    return 0;
}

LuaDefine(math_random, "(args...)",
    "|Generate random numbers."
    "|"
    "|What it generates depends on the arguments:"
    "|"
    "|   ()          - a float in range [0.0, 1.0)"
    "|   (high)      - an int between 1 and high inclusive"
    "|   (low, high) - an int between low and high inclusive"
    "|"
    "|You may also pass in a randomstate table"
    "|as an optional first argument."
    "|"
    "|math.random tries to cooperate with predictive"
    "|reexecution to be as predictable as possible."
    "|To achieve predictability, we used an ad-hoc"
    "|random number generator.  It passes a variety of"
    "|statistical tests, but it's not well-studied."
    "|"
    "|If you want actually want nonpredictability, or"
    "|if you need the assurance of a well-studied random"
    "|number generator, use math.mtrandom or"
    "|math.cryptrandom instead.") {
    // Parse the arguments.
    // This is hairy because there's a lot of possibilities.
    bool passed_in_randomstate = false;
    int arg = 1;
    if ((lua_gettop(L) >= arg) && (lua_istable(L, arg))) {
        passed_in_randomstate = true;
        arg += 1;
    }
    bool have_range = false;
    int64_t low, high;
    if ((lua_gettop(L) >= arg) && (lua_type(L, arg) == LUA_TNUMBER)) {
        double lowf, highf;
        if ((lua_gettop(L) >= arg+1) && (lua_type(L, arg+1) == LUA_TNUMBER)) {
            lowf = std::floor(lua_tonumber(L, arg));
            highf = std::floor(lua_tonumber(L, arg + 1));
            arg += 2;
        } else {
            lowf = 1;
            highf = std::floor(lua_tonumber(L, arg));
            arg += 1;
        }
        if ((lowf < -LuaStack::MAXINT) || (highf > LuaStack::MAXINT)) {
            luaL_error(L, "math.random range exceeds MAXINT");
            return 0;
        }
        if (lowf > highf) {
            luaL_error(L, "math.random range low > high");
            return 0;
        }
        low = int64_t(lowf);
        high = int64_t(highf);
        have_range = true;
    }
    if (lua_gettop(L) >= arg) {
        luaL_error(L, "math.random accepts an optional randomstate and an optional range");
        return 0;
    }

    // Generate the seed, count, and salt.
    // The salt prevents accidental duplication between user-specified
    // seeds and system-generated seeds.
    uint64_t seed, count, salt;
    if (passed_in_randomstate) {
        lua_pushstring(L, "seed");
        lua_rawget(L, 1);
        lua_pushstring(L, "count");
        lua_rawget(L, 1);
        if ((lua_type(L, -1) != LUA_TNUMBER) ||
            (lua_type(L, -2) != LUA_TNUMBER)) {
            luaL_error(L, "Not a valid randomstate table");
            return 0;
        }
        double dseed = lua_tonumber(L, -2);
        double dcount = lua_tonumber(L, -1);
        seed = uint64_t(dseed) & LuaStack::MAXINT;
        count = uint64_t(dcount) & LuaStack::MAXINT;
        if (dseed < 0) {
            salt = 0x35c9a6082a097ade;
        } else {
            salt = 0x4785d086ead90c20;
        }
        lua_pop(L, 2);
        lua_pushstring(L, "count");
        lua_pushnumber(L, double((count + 1) & LuaStack::MAXINT));
        lua_rawset(L, 1);
    } else {
        World *w = World::fetch_global_pointer(L);
        if (w->lthread_use_ppool_) {
            Tangible *actor = w->tangible_get(w->lthread_actor_id_);
            seed = w->lthread_actor_id_;
            count = actor->id_player_pool_.get_seqno();
            salt = 0x3ab0fb84aedc3764;
        } else {
            // TODO: maybe throw in a 'donotpredict' here.
            seed = 123456;
            count = w->id_global_pool_.get_seqno();
            salt = 0x6f493c90faf0139d;
        }
    }

    if (!have_range) {
        // Generate the hash and convert to a double.
        uint64_t hash = util::hash_ints(seed, count, salt, 456);
        lua_pushnumber(L, util::hash_to_double(hash));
    } else {
        // Generate the hash and scale it into the desired range.
        // This code is not quite right: the results are not quite
        // uniform, this is especially true for very long ranges.
        uint64_t hash = util::hash_ints(seed, count, salt, 456);
        uint64_t range = (high - low) + 1;
        uint64_t offset = (hash & 0x7FFFFFFFFFFFFFFF) % range;
        int64_t result = low + int64_t(offset);
        lua_pushnumber(L, result);
    }
    return 1;
}

LuaDefine(math_randomstate, "seed",
    "|Create and return a randomstate table."
    "|This is a lua table that stores the state for a random"
    "|number generator.  A randomstate table can be passed"
    "|to math.random."
    "|"
    "|You can optionally omit the seed, in which case a"
    "|seed will be chosen randomly.  Automatically-generated"
    "|seeds are guaranteed never to be the same as"
    "|user-specified seeds.") {
    double seed;
    if (lua_gettop(L) == 0) {
        World *w = World::fetch_global_pointer(L);
        int64_t iseed = (w->id_global_pool_.get_seqno() & LuaStack::MAXINT) + 1;
        seed = -iseed;
    } else if (lua_gettop(L) == 1) {
        if (lua_type(L, 1) != LUA_TNUMBER) {
            luaL_error(L, "math.randomstate takes an optional integer seed");
            return 0;
        }
        seed = lua_tonumber(L, 1);
        if ((seed < 0.0) || (seed > LuaStack::MAXINT) || (std::floor(seed) != seed)) {
            luaL_error(L, "math.randomstate seed must be an integer 0-MAXINT");
            return 0;
        }
    } else {
        luaL_error(L, "math.randomstate takes an optional integer seed");
        return 0;
    }

    lua_newtable(L);
    lua_pushstring(L, "seed");
    lua_pushnumber(L, seed);
    lua_rawset(L, -3);
    lua_pushstring(L, "count");
    lua_pushnumber(L, 0);
    lua_rawset(L, -3);
    return 1;
}

LuaSandboxBuiltin(math_randomseed, "", "");


LuaDefine(pprint, "obj1,obj2,...",
    "|Pretty-print object or objects.") {
    World *w = World::fetch_global_pointer(L);
    std::ostream *ostream = w->lthread_print_stream();
    LuaStack LS(L);
    for (int i = 1; i <= lua_gettop(L); i++) {
        LuaSpecial root(i);
        pprint(LS, root, true, ostream);
        (*ostream) << std::endl;
    }
    return LS.result();
}

LuaDefine(print, "obj1,obj2,...", 
    "|Print object or objects.") {
    World *w = World::fetch_global_pointer(L);
    std::ostream *ostream = w->lthread_print_stream();
    LuaStack LS(L);
    int n = lua_gettop(L);
    for (int i = 1; i <= n; i++) {
        LuaSpecial root(i);
        atomic_print(LS, root, false, ostream);
        if (i < n) (*ostream) << " ";
    }
    (*ostream) << std::endl;
    return LS.result();
}

LuaDefine(doc, "function",
    "|Print documentation for specified function.") {
    World *w = World::fetch_global_pointer(L);
    std::ostream *ostream = w->lthread_print_stream();
    LuaArg func;
    LuaStack LS(L, func);
    eng::string doc = SourceDB::function_docs(LS, func);
    if (doc == "") {
        (*ostream) << "no doc found" << std::endl;
    }
    (*ostream) << doc;
    return LS.result();
}

int lfn_http_request(lua_State *L, const char *method) {
    World *w = World::fetch_global_pointer(L);
    w->guard_blockable(L, "http.get");

    LuaArg request;
    LuaRet response;
    LuaStack LS(L, request, response);
    HttpClientRequest req;
    
    // Parse the request and make sure it's valid.
    // If not, immediately pass a '400 bad request' back to lua.
    req.set_method(method);
    req.set_config(LS, request);
    req.set_defaults();
    eng::string error = req.check();
    if (!error.empty()) {
        HttpParser::store_fail(LS, response, 400, util::ss("Bad Request: ", error));
        return LS.result();
    }

    // Give the request an ID.
    req.set_request_id(w->id_global_pool_.get_one());
    req.set_place_id(w->lthread_place_id_);
    req.set_thread_id(w->lthread_thread_id_);

    // Store it in the global request table.
    w->http_requests_[req.request_id()] = req;

    // Block.
    return lua_yield(L, 0);
}

LuaDefine(http_get, "request",
    "|Make an HTTP GET request.  Returns an HTTP response."
    "|See doc(http.clientrequest) and doc(http.clientresponse).") {
    return lfn_http_request(L, "GET");
}

LuaDefine(http_head, "request",
    "|Make an HTTP HEAD request.  Returns an HTTP response."
    "|See doc(http.clientrequest) and doc(http.clientresponse).") {
    return lfn_http_request(L, "HEAD");
}

LuaDefine(http_post, "request",
    "|Make an HTTP POST request.  Returns an HTTP response."
    "|See doc(http.clientrequest) and doc(http.clientresponse).") {
    return lfn_http_request(L, "POST");
}