// testTeardown.c -- a library registry that holds a SCRIPT function must let go of it while the
// owning context is still alive.
//
// A CalogFnT is a handle to a function living inside a VM. If a process-global registry (a pubsub
// subscriber, an exported function, a timer callback) still holds one when that context's
// interpreter is destroyed, the release arrives too late to run the engine's own release hook and
// the script object is never freed inside its VM. That is what the two destroy phases are for: a
// library holding context-owned references registers calogDestroyBeforeContextsE, so calogDestroy
// drains it while every context is still serving its queue.
//
// Most VMs hide the mistake -- they free everything on close -- so this test uses JavaScript on
// purpose: QuickJS asserts it owns no live objects at JS_FreeRuntime and ABORTS the process. Every
// case here therefore checks the same thing in the end: that we are still running afterwards. A
// wrong phase does not fail a check, it kills the binary (and LeakSanitizer catches the milder
// variant, a registry resurrected after its shutdown).

#define _POSIX_C_SOURCE 200809L

#include "calog.h"

#include "calogExport.h"
#include "calogPubsub.h"
#include "calogTimer.h"
#include "calogInternal.h"   // calogPubsubShutdown/calogExportShutdown: internal, driven by hand here

#include <stdatomic.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <time.h>

#define CHECK(cond, msg) checkImpl((cond), (msg), __LINE__)

#define PUMP_INTERVAL_NS 500000
#define PUMP_LIMIT       4000

static CalogT          *calog       = NULL;
static _Atomic bool     readyFlag   = false;
static _Atomic int32_t  reportValue = -1;
static _Atomic int32_t  errorCount  = 0;
static int32_t          testsRun    = 0;
static int32_t          testsFailed = 0;

static void    checkImpl(bool condition, const char *message, int32_t line);
static int32_t nativeEndSelf(CalogValueT *args, int32_t argCount, CalogValueT *result, void *userData);
static int32_t nativeReady(CalogValueT *args, int32_t argCount, CalogValueT *result, void *userData);
static int32_t nativeReport(CalogValueT *args, int32_t argCount, CalogValueT *result, void *userData);
static void    onError(uint64_t contextId, const char *message, void *userData);
static void    pumpUntilReady(void);
static void    startRuntime(void);
static void    testCrossEngineValueOutlivesOwner(void);
static void    testGuardsAfterShutdown(void);
static void    testHeldCallableSurvivesTeardown(const char *what, const char *source);
static void    testOwnerDiesBeforeTheRuntime(const char *what, const char *source, bool expectError);


static void checkImpl(bool condition, const char *message, int32_t line) {
    testsRun++;
    if (!condition) {
        testsFailed++;
        printf("FAIL testTeardown.c:%d  %s\n", line, message);
    }
}


// calogAbortCurrent: end THIS script, leaving the runtime and every other script running. Inline,
// so it runs on the calling script's own thread and can unwind it.
static int32_t nativeEndSelf(CalogValueT *args, int32_t argCount, CalogValueT *result, void *userData) {
    (void)args;
    (void)argCount;
    (void)userData;
    calogValueNil(result);
    return calogAbortCurrent(result);
}


static int32_t nativeReady(CalogValueT *args, int32_t argCount, CalogValueT *result, void *userData) {
    (void)args;
    (void)argCount;
    (void)userData;
    atomic_store(&readyFlag, true);
    calogValueNil(result);
    return calogOkE;
}


static int32_t nativeReport(CalogValueT *args, int32_t argCount, CalogValueT *result, void *userData) {
    (void)userData;
    calogValueNil(result);
    if (argCount == 1 && args[0].type == calogBoolE) {
        atomic_store(&reportValue, args[0].as.b ? 1 : 0);
    }
    return calogOkE;
}


static void onError(uint64_t contextId, const char *message, void *userData) {
    (void)contextId;
    (void)userData;
    atomic_fetch_add(&errorCount, 1);
    printf("       (error handler saw: %s)\n", message != NULL ? message : "(null)");
}


static void pumpUntilReady(void) {
    struct timespec tick = { 0, PUMP_INTERVAL_NS };
    int32_t         index;

    for (index = 0; index < PUMP_LIMIT; index++) {
        calogPump(calog);
        if (atomic_load(&readyFlag)) {
            calogPump(calog);
            return;
        }
        nanosleep(&tick, NULL);
    }
}


// A runtime with the three libraries that hold script functions, plus the two natives a script
// signals through.
static void startRuntime(void) {
    calog = calogCreate();
    if (calog == NULL) {
        CHECK(false, "runtime create failed");
        return;
    }
    calogSetErrorHandler(calog, onError, NULL);
    calogRegisterInline(calog, "ready", nativeReady, NULL);
    calogRegisterInline(calog, "report", nativeReport, NULL);
    calogRegisterInline(calog, "endSelf", nativeEndSelf, NULL);
    calogPubsubRegister(calog);
    calogExportRegister(calog);
    calogTimerRegister(calog);
    atomic_store(&readyFlag, false);
    atomic_store(&reportValue, -1);
    atomic_store(&errorCount, 0);
}


// Once a library's registry has been drained, a native that would store a NEW script function in it
// has to fail: re-growing a registry that nothing will ever free again would strand the callable it
// holds (the very leak the phase fix exists to prevent). Reads stay safe, which is what the pubsub
// and export tests already rely on.
static void testGuardsAfterShutdown(void) {
    CalogContextT *ctx;

    startRuntime();
    if (calog == NULL) {
        return;
    }
    ctx = calogContextOpen(calog, &calogLuaEngine);
    if (ctx == NULL) {
        CHECK(false, "guards: context open failed");
        calogDestroy(calog);
        return;
    }

    calogPubsubShutdown();
    calogExportShutdown();

    // pcall yields (ok, err), so bind ok first -- report takes exactly one value.
    calogContextEval(ctx, "local ok = pcall(psSubscribe, 't', function() end)\n report(ok)\n ready()");
    pumpUntilReady();
    CHECK(atomic_load(&reportValue) == 0, "psSubscribe after the pubsub registry is drained fails cleanly");

    atomic_store(&readyFlag, false);
    atomic_store(&reportValue, -1);
    calogContextEval(ctx, "local ok = pcall(calogExport, 'e', function() end)\n report(ok)\n ready()");
    pumpUntilReady();
    CHECK(atomic_load(&reportValue) == 0, "calogExport after the export registry is drained fails cleanly");

    // Reads stay safe either way: a publish simply finds nobody, and an unknown global still
    // resolves to nil through the export hook.
    atomic_store(&readyFlag, false);
    atomic_store(&reportValue, -1);
    calogContextEval(ctx, "report(psPublish('t', 1) == 0 and someUndefinedGlobalName == nil)\n ready()");
    pumpUntilReady();
    CHECK(atomic_load(&reportValue) == 1, "publishing and resolving after shutdown stay safe");

    calogContextClose(ctx);
    calogDestroy(calog);
}


// Run source on a JavaScript context, leave whatever it registered in place, and tear the runtime
// down with calogDestroy alone -- the path a real host takes. Surviving IS the check.
static void testHeldCallableSurvivesTeardown(const char *what, const char *source) {
    CalogContextT *ctx;

    printf("  teardown case: %s\n", what);
    fflush(stdout);
    startRuntime();
    if (calog == NULL) {
        return;
    }
    ctx = calogContextOpen(calog, &calogJsEngine);
    if (ctx == NULL) {
        checkImpl(false, what, __LINE__);
        calogDestroy(calog);
        return;
    }
    calogContextEval(ctx, source);
    pumpUntilReady();
    checkImpl(atomic_load(&readyFlag), what, __LINE__);
    checkImpl(atomic_load(&errorCount) == 0, "the script registered its callbacks without error", __LINE__);
    // No calogContextClose and no by-hand library shutdown: calogDestroy must get the order right
    // on its own, which is exactly what the destroy-hook phases are for.
    calogDestroy(calog);
    checkImpl(true, what, __LINE__);
}


// The other half of the rule, and the one the destroy phases cannot reach: a context that dies while
// the RUNTIME lives on -- a script that errors out, or one that ends itself -- has to
// reclaim its handles just the same. Its interpreter is destroyed on its own thread the moment it
// stops, long before anyone tears the runtime down.
static void testOwnerDiesBeforeTheRuntime(const char *what, const char *source, bool expectError) {
    CalogContextT  *ctx;
    struct timespec tick = { 0, PUMP_INTERVAL_NS };
    int32_t         index;
    bool            finished;

    printf("  early-death case: %s\n", what);
    fflush(stdout);
    startRuntime();
    if (calog == NULL) {
        return;
    }
    ctx = calogContextOpen(calog, &calogJsEngine);
    if (ctx == NULL) {
        checkImpl(false, what, __LINE__);
        calogDestroy(calog);
        return;
    }
    calogContextEval(ctx, source);
    // Wait for the context's own thread to exit: an errored script is retired by the test's error
    // handler doing nothing at all -- the context ends because the script ended it (endSelf) or
    // because we close it below.
    finished = false;
    for (index = 0; index < PUMP_LIMIT; index++) {
        calogPump(calog);
        if (calogContextFinished(ctx)) {
            finished = true;
            break;
        }
        if (expectError && atomic_load(&errorCount) > 0) {
            break;
        }
        nanosleep(&tick, NULL);
    }
    if (expectError) {
        checkImpl(atomic_load(&errorCount) > 0, "the script's failure was reported", __LINE__);
    } else {
        checkImpl(finished, "endSelf ended the script, so its context can be reaped", __LINE__);
        checkImpl(atomic_load(&errorCount) == 0, "ending a script is not reported as a failure", __LINE__);
    }
    // Closing joins the thread, which is where the interpreter is destroyed -- the moment a handle
    // that outlived its VM would take the process down.
    calogContextClose(ctx);
    calogPump(calog);
    checkImpl(true, what, __LINE__);
    calogDestroy(calog);
}


// A function value that crossed engines: JavaScript hands its own closure to a Lua script, which
// keeps it, and then the JavaScript context dies. No library registry holds the closure -- the other
// VM does -- so only reclaiming on the owner's own thread can save it.
static void testCrossEngineValueOutlivesOwner(void) {
    CalogContextT  *holder;
    CalogContextT  *giver;
    struct timespec tick = { 0, PUMP_INTERVAL_NS };
    int32_t         index;

    printf("  early-death case: a JS closure kept by a Lua script when JS dies\n");
    fflush(stdout);
    startRuntime();
    if (calog == NULL) {
        return;
    }
    holder = calogContextOpen(calog, &calogLuaEngine);
    giver  = calogContextOpen(calog, &calogJsEngine);
    if (holder == NULL || giver == NULL) {
        checkImpl(false, "cross-engine: context open failed", __LINE__);
        calogDestroy(calog);
        return;
    }
    calogContextEval(holder, "held = nil\n calogExport('keep', function(fn) held = fn return 1 end)\n ready()");
    pumpUntilReady();
    checkImpl(atomic_load(&readyFlag), "the Lua holder published its keep() export", __LINE__);

    atomic_store(&readyFlag, false);
    calogContextEval(giver, "calogCall('keep', function () { return 42; }); ready(); endSelf();");
    pumpUntilReady();
    for (index = 0; index < PUMP_LIMIT; index++) {
        calogPump(calog);
        if (calogContextFinished(giver)) {
            break;
        }
        nanosleep(&tick, NULL);
    }
    checkImpl(calogContextFinished(giver), "the giving context ended itself", __LINE__);
    calogContextClose(giver);   // joins: the JS interpreter is destroyed here
    calogPump(calog);
    checkImpl(atomic_load(&errorCount) == 0, "no error while the JS owner went away", __LINE__);

    // The Lua script still holds the (now dead) closure. Invoking it must fail cleanly rather than
    // reach into the destroyed VM, and dropping it must not double-free anything.
    atomic_store(&readyFlag, false);
    atomic_store(&reportValue, -1);
    calogContextEval(holder, "local ok = pcall(held)\n report(ok)\n held = nil\n ready()");
    pumpUntilReady();
    checkImpl(atomic_load(&reportValue) == 0, "invoking a callable whose owner is gone fails cleanly", __LINE__);

    calogContextClose(holder);
    calogDestroy(calog);
}


int main(void) {
    testHeldCallableSurvivesTeardown("a JS subscriber still registered at teardown",
        "psSubscribe('t', function () { return 1; }); ready();");
    testHeldCallableSurvivesTeardown("a JS export still registered at teardown",
        "calogExport('e', function () { return 1; }); ready();");
    testHeldCallableSurvivesTeardown("a JS timer callback still armed at teardown",
        "timerEvery(1000, function () {}); ready();");
    testHeldCallableSurvivesTeardown("all three at once, several callbacks each",
        "psSubscribe('a', function () {}); psSubscribe('b', function () {});"
        "calogExport('x', function () {}); calogExport('y', function () {});"
        "timerEvery(1000, function () {}); timerAfter(1000, function () {});"
        "ready();");
    testOwnerDiesBeforeTheRuntime("a JS subscriber whose script then errors out",
        "psSubscribe('t', function () {}); ready(); throw new Error('boom');", true);
    testOwnerDiesBeforeTheRuntime("a JS export whose script then errors out",
        "calogExport('e', function () {}); ready(); throw new Error('boom');", true);
    testOwnerDiesBeforeTheRuntime("a JS timer callback whose script then errors out",
        "timerEvery(1000, function () {}); ready(); throw new Error('boom');", true);
    testOwnerDiesBeforeTheRuntime("a JS subscriber whose script ends itself",
        "psSubscribe('t', function () {}); ready(); endSelf();", false);
    testCrossEngineValueOutlivesOwner();
    testGuardsAfterShutdown();

    printf("\n%d checks, %d failed\n", testsRun, testsFailed);
    fflush(stdout);
    return testsFailed == 0 ? 0 : 1;
}