/** SpiderMonkey support for both user scripts and web scripts.
 * @file */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "elinks.h"

#include "ecmascript/spidermonkey-shared.h"
#include "ecmascript/spidermonkey.h"
#include "scripting/smjs/core.h"

/** A shared runtime used for both user scripts (scripting/smjs/) and
 * scripts on web pages (ecmascript/spidermonkey/).
 *
 * SpiderMonkey has bugs that corrupt memory when multiple JSRuntimes
 * are used: https://bugzilla.mozilla.org/show_bug.cgi?id=378918 and
 * perhaps others.  */
JSRuntime *spidermonkey_runtime;

/** A JSContext that can be used in JS_SetPrivate and JS_GetPrivate
 * when no better one is available.  This context has no global
 * object, so scripts cannot be evaluated in it.
 *
 * XXX: This also works around a crash on exit.  SMJS will crash on
 * JS_DestroyRuntime if the given runtime has never had any context
 * created, which will be the case if one closes ELinks without having
 * loaded any documents.  */
JSContext *spidermonkey_empty_context;

/** A reference count for ::spidermonkey_runtime so that modules using
 * it can be initialized and shut down in arbitrary order.  */
static int spidermonkey_runtime_refcount;

static void
error_reporter(JSContext *ctx, const char *message, JSErrorReport *report)
{
	/* We have three types of JSContexts.
	 * - spidermonkey_empty_context never has anything defined or
	 *   evaluated in it, so this error_reporter() should not be
	 *   called for it.
	 * - smjs_ctx for user scripts.
	 * - many JSContexts for web scripts.
	 * Check which one ctx is and call the appropriate function.
	 *
	 * Instead of the scheme used here, we could:
	 * (a) make the private pointer of every context point to a
	 *     structure of known type and put a function pointer or
	 *     enum in that structure, or
	 * (b) assume that JS_GetContextPrivate(smjs_ctx) == NULL.  */

	assert(ctx != spidermonkey_empty_context);
	if_assert_failed return;

#ifdef CONFIG_SCRIPTING_SPIDERMONKEY
	if (ctx == smjs_ctx) {
		smjs_error_reporter(ctx, message, report);
		return;
	}
#endif

#ifdef CONFIG_ECMASCRIPT_SMJS
	spidermonkey_error_reporter(ctx, message, report);
#endif
}

/** Initialize ::spidermonkey_runtime and ::spidermonkey_empty_context.
 * If already initialized, just increment the reference count.
 *
 * @return 1 if successful or 0 on error.  If this succeeds, the
 * caller must eventually call spidermonkey_runtime_release().  */
int
spidermonkey_runtime_addref(void)
{
	if (spidermonkey_runtime_refcount == 0) {
		assert(spidermonkey_runtime == NULL);
		assert(spidermonkey_empty_context == NULL);
		if_assert_failed return 0;

		spidermonkey_runtime = JS_NewRuntime(4L * 1024L * 1024L);
		if (!spidermonkey_runtime) return 0;
		
		spidermonkey_empty_context = JS_NewContext(spidermonkey_runtime,
							   0);
		if (!spidermonkey_empty_context) {
			/* Perhaps JS_DestroyRuntime will now crash
			 * because no context was created, but there's
			 * not much else to do.  */
			JS_DestroyRuntime(spidermonkey_runtime);
			spidermonkey_runtime = NULL;
			JS_ShutDown();
			return 0;
		}

		/* Although JS_SetErrorReporter gets the JSContext as
		 * a parameter, it affects the whole JSRuntime.  */
		JS_SetErrorReporter(spidermonkey_empty_context,
				    error_reporter);
	}

	assert(spidermonkey_runtime);
	assert(spidermonkey_empty_context);
	spidermonkey_runtime_refcount++;
	assert(spidermonkey_runtime_refcount > 0);
	if_assert_failed { spidermonkey_runtime_refcount--; return 0; }
	return 1;
}

/** Release a reference to ::spidermonkey_runtime, and destroy it if
 * that was the last reference.  If spidermonkey_runtime_addref()
 * failed, then this must not be called.  */
void
spidermonkey_runtime_release(void)
{
	assert(spidermonkey_runtime_refcount > 0);
	assert(spidermonkey_runtime);
	assert(spidermonkey_empty_context);
	if_assert_failed return;

	--spidermonkey_runtime_refcount;
	if (spidermonkey_runtime_refcount == 0) {
		JS_DestroyContext(spidermonkey_empty_context);
		spidermonkey_empty_context = NULL;
		JS_DestroyRuntime(spidermonkey_runtime);
		spidermonkey_runtime = NULL;
		JS_ShutDown();
	}
}

/** An ELinks-specific replacement for JS_DefineFunctions().
 *
 * @relates spidermonkeyFunctionSpec */
JSBool
spidermonkey_DefineFunctions(JSContext *cx, JSObject *obj,
			     const spidermonkeyFunctionSpec *fs)
{
	for (; fs->name; fs++) {
		if (!JS_DefineFunction(cx, obj, fs->name, fs->call,
				       fs->nargs, 0))
			return JS_FALSE;
	}
	return JS_TRUE;
}

/** An ELinks-specific replacement for JS_InitClass().
 *
 * @relates spidermonkeyFunctionSpec */
JSObject *
spidermonkey_InitClass(JSContext *cx, JSObject *obj,
		       JSObject *parent_proto, JSClass *clasp,
		       JSNative constructor, uintN nargs,
		       JSPropertySpec *ps,
		       const spidermonkeyFunctionSpec *fs,
		       JSPropertySpec *static_ps,
		       const spidermonkeyFunctionSpec *static_fs)
{
	JSObject *proto = JS_InitClass(cx, obj, parent_proto, clasp,
				       constructor, nargs,
				       ps, NULL, static_ps, NULL);

	if (proto == NULL)
		return NULL;

	if (fs) {
		if (!spidermonkey_DefineFunctions(cx, proto, fs))
			return NULL;
	}

	if (static_fs) {
		JSObject *cons_obj = JS_GetConstructor(cx, proto);

		if (cons_obj == NULL)
			return NULL;
		if (!spidermonkey_DefineFunctions(cx, cons_obj, static_fs))
			return NULL;
	}

	return proto;
}