/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil; -*- */
// SPDX-License-Identifier: MIT OR LGPL-2.0-or-later
// SPDX-FileCopyrightText: 2008 litl, LLC
// SPDX-FileCopyrightText: 2009 Red Hat, Inc.

#include <config.h>

#ifdef _WIN32
#    include <windows.h>
#endif

#include <algorithm>  // for min
#include <chrono>  // for duration, operator""us
#include <sstream>
#include <string>
#include <utility>  // for move
#include <vector>

#include <js/AllocPolicy.h>
#include <js/Array.h>
#include <js/CallAndConstruct.h>  // for Call
#include <js/CallArgs.h>
#include <js/CharacterEncoding.h>
#include <js/Class.h>
#include <js/ColumnNumber.h>  // for TaggedColumnNumberOneOrigin
#include <js/Conversions.h>
#include <js/ErrorReport.h>
#include <js/Exception.h>
#include <js/GCAPI.h>        // for JS_MaybeGC, NonIncrementalGC, GCRe...
#include <js/GCHashTable.h>  // for GCHashSet
#include <js/GCVector.h>     // for RootedVector
#include <js/HashTable.h>    // for DefaultHasher
#include <js/Object.h>       // for GetClass
#include <js/PropertyAndElement.h>
#include <js/PropertyDescriptor.h>  // for JSPROP_ENUMERATE
#include <js/RootingAPI.h>
#include <js/SavedFrameAPI.h>
#include <js/String.h>
#include <js/TypeDecls.h>
#include <js/Value.h>
#include <js/ValueArray.h>
#include <jsapi.h>        // for JS_InstanceOf
#include <jsfriendapi.h>  // for ProtoKeyToClass
#include <jspubtd.h>      // for JSProto_InternalError, JSProto_SyntaxError
#include <mozilla/ScopeExit.h>

#include "gjs/atoms.h"
#include "gjs/auto.h"
#include "gjs/context-private.h"
#include "gjs/global.h"
#include "gjs/jsapi-util.h"
#include "gjs/macros.h"
#include "gjs/module.h"
#include "util/misc.h"

static void throw_property_lookup_error(JSContext* cx, JS::HandleObject obj,
                                        const char* description,
                                        JS::HandleId property_name,
                                        const char* reason) {
    /* remember gjs_throw() is a no-op if JS_GetProperty() already set an
     * exception
     */
    if (description)
        gjs_throw(cx, "No property '%s' in %s (or %s)",
                  gjs_debug_id(property_name).c_str(), description, reason);
    else
        gjs_throw(cx, "No property '%s' in object %p (or %s)",
                  gjs_debug_id(property_name).c_str(), obj.get(), reason);
}

/* Returns whether the object had the property; if the object did not have the
 * property, always sets an exception. Treats "the property's value is
 * undefined" the same as "no such property,". Guarantees that value_p is set to
 * something, if only JS::UndefinedValue(), even if an exception is set and
 * false is returned.
 *
 * SpiderMonkey will emit a warning if the property is not present, so don't use
 * this if you expect the property not to be present some of the time.
 */
bool gjs_object_require_property(JSContext* cx, JS::HandleObject obj,
                                 const char* obj_description,
                                 JS::HandleId property_name,
                                 JS::MutableHandleValue value) {
    value.setUndefined();

    if (G_UNLIKELY(!JS_GetPropertyById(cx, obj, property_name, value)))
        return false;

    if (G_LIKELY(!value.isUndefined()))
        return true;

    throw_property_lookup_error(cx, obj, obj_description, property_name,
                                "its value was undefined");
    return false;
}

bool gjs_object_require_property(JSContext* cx, JS::HandleObject obj,
                                 const char* description,
                                 JS::HandleId property_name, bool* value) {
    JS::RootedValue prop_value(cx);
    if (JS_GetPropertyById(cx, obj, property_name, &prop_value) &&
        prop_value.isBoolean()) {
        *value = prop_value.toBoolean();
        return true;
    }

    throw_property_lookup_error(cx, obj, description, property_name,
                                "it was not a boolean");
    return false;
}

bool gjs_object_require_property(JSContext* cx, JS::HandleObject obj,
                                 const char* description,
                                 JS::HandleId property_name, int32_t* value) {
    JS::RootedValue prop_value(cx);
    if (JS_GetPropertyById(cx, obj, property_name, &prop_value) &&
        prop_value.isInt32()) {
        *value = prop_value.toInt32();
        return true;
    }

    throw_property_lookup_error(cx, obj, description, property_name,
                                "it was not a 32-bit integer");
    return false;
}

// Converts JS string value to UTF-8 string.
bool gjs_object_require_property(JSContext* cx, JS::HandleObject obj,
                                 const char* description,
                                 JS::HandleId property_name,
                                 JS::UniqueChars* value) {
    JS::RootedValue prop_value(cx);
    if (JS_GetPropertyById(cx, obj, property_name, &prop_value)) {
        JS::UniqueChars tmp = gjs_string_to_utf8(cx, prop_value);
        if (tmp) {
            *value = std::move(tmp);
            return true;
        }
    }

    throw_property_lookup_error(cx, obj, description, property_name,
                                "it was not a valid string");
    return false;
}

bool gjs_object_require_property(JSContext* cx, JS::HandleObject obj,
                                 const char* description,
                                 JS::HandleId property_name,
                                 JS::MutableHandleObject value) {
    JS::RootedValue prop_value(cx);
    if (JS_GetPropertyById(cx, obj, property_name, &prop_value) &&
        prop_value.isObject()) {
        value.set(&prop_value.toObject());
        return true;
    }

    throw_property_lookup_error(cx, obj, description, property_name,
                                "it was not an object");
    return false;
}

bool gjs_object_require_converted_property(JSContext* cx, JS::HandleObject obj,
                                           const char* description,
                                           JS::HandleId property_name,
                                           uint32_t* value) {
    JS::RootedValue prop_value(cx);
    if (JS_GetPropertyById(cx, obj, property_name, &prop_value) &&
        JS::ToUint32(cx, prop_value, value)) {
        return true;
    }

    throw_property_lookup_error(cx, obj, description, property_name,
                                "it couldn't be converted to uint32");
    return false;
}

void gjs_throw_constructor_error(JSContext* cx) {
    gjs_throw(cx,
              "Constructor called as normal method. Use 'new SomeObject()' not "
              "'SomeObject()'");
}

void gjs_throw_abstract_constructor_error(JSContext* cx,
                                          const JS::CallArgs& args) {
    const char* name = "anonymous";

    const GjsAtoms& atoms = GjsContextPrivate::atoms(cx);
    JS::RootedObject callee{cx, &args.callee()};
    JS::RootedValue prototype{cx};
    if (JS_GetPropertyById(cx, callee, atoms.prototype(), &prototype)) {
        const JSClass* proto_class = JS::GetClass(&prototype.toObject());
        name = proto_class->name;
    }

    gjs_throw(cx, "You cannot construct new instances of '%s'", name);
}

JSObject* gjs_build_string_array(JSContext* cx,
                                 const std::vector<std::string>& strings) {
    JS::RootedValueVector elems{cx};
    if (!elems.reserve(strings.size())) {
        JS_ReportOutOfMemory(cx);
        return nullptr;
    }

    for (const std::string& string : strings) {
        JS::ConstUTF8CharsZ chars(string.c_str(), string.size());
        JS::RootedValue element{
            cx, JS::StringValue(JS_NewStringCopyUTF8Z(cx, chars))};
        elems.infallibleAppend(element);
    }

    return JS::NewArrayObject(cx, elems);
}

JSObject* gjs_define_string_array(JSContext* cx, JS::HandleObject in_object,
                                  const char* array_name,
                                  const std::vector<std::string>& strings,
                                  unsigned attrs) {
    JS::RootedObject array{cx, gjs_build_string_array(cx, strings)};
    if (!array)
        return nullptr;

    if (!JS_DefineProperty(cx, in_object, array_name, array, attrs))
        return nullptr;

    return array;
}

// Helper function: perform ToString on an exception (which may not even be an
// object), except if it is an InternalError, which would throw in ToString.
GJS_JSAPI_RETURN_CONVENTION
static JSString* exception_to_string(JSContext* cx, JS::HandleValue exc) {
    if (exc.isObject()) {
        JS::RootedObject exc_obj(cx, &exc.toObject());
        const JSClass* internal_error =
            js::ProtoKeyToClass(JSProto_InternalError);
        if (JS_InstanceOf(cx, exc_obj, internal_error, nullptr)) {
            JSErrorReport* report = JS_ErrorFromException(cx, exc_obj);
            if (!report->message())
                return JS_NewStringCopyZ(cx, "(unknown internal error)");
            return JS_NewStringCopyUTF8Z(cx, report->message());
        }
    }

    return JS::ToString(cx, exc);
}

// Helper function: log and clear the pending exception, without calling into
// any JS APIs that might cause more exceptions to be thrown.
static void log_exception_brief(JSContext* cx) {
    JS::RootedValue exc{cx};
    if (!JS_GetPendingException(cx, &exc))
        return;

    JS_ClearPendingException(cx);

    if (!exc.isObject()) {
        g_warning("Value thrown while printing exception: %s",
                  gjs_debug_value(exc).c_str());
        return;
    }

    JS::RootedObject exc_obj{cx, &exc.toObject()};
    JSErrorReport* report = JS_ErrorFromException(cx, exc_obj);
    if (!report) {
        g_warning("Non-Error Object thrown while printing exception: %s",
                  gjs_debug_object(exc_obj).c_str());
        return;
    }

    g_warning("Exception thrown while printing exception: %s:%u:%u: %s",
              report->filename.c_str(), report->lineno,
              report->column.oneOriginValue(), report->message().c_str());
}

// Helper function: format the error's stack property.
static std::string format_exception_stack(JSContext* cx, JS::HandleObject exc) {
    auto Ok = JS::SavedFrameResult::Ok;
    JS::AutoSaveExceptionState saved_exc(cx);
    auto restore =
        mozilla::MakeScopeExit([&saved_exc]() { saved_exc.restore(); });

    const GjsAtoms& atoms = GjsContextPrivate::atoms(cx);
    std::ostringstream out;

    // Check both the internal SavedFrame object and the stack property.
    // GErrors will not have the former, and internal errors will not
    // have the latter.
    JS::RootedObject saved_frame{cx, JS::ExceptionStackOrNull(exc)};
    if (saved_frame) {
        GjsContextPrivate* gjs = GjsContextPrivate::from_cx(cx);
        Gjs::AutoMainRealm ar{gjs};
        JS::RootedObject global{cx, gjs->global()};
        JS::RootedObject registry{cx, gjs_get_source_map_registry(global)};

        JS::UniqueChars utf8_stack{format_saved_frame(cx, saved_frame)};
        if (!utf8_stack)
            return {};

        char* utf8_stack_str = utf8_stack.get();
        std::stringstream ss{utf8_stack_str};
        // append source map info when available to each line
        while (saved_frame) {
            JS::RootedObject consumer{cx};
            JS::RootedString source_string{cx};
            uint32_t line;
            JS::TaggedColumnNumberOneOrigin column;
            std::string stack_line;

            // print the original stack trace
            std::getline(ss, stack_line, '\n');
            out << '\n' << stack_line;

            bool success =
                JS::GetSavedFrameSource(cx, nullptr, saved_frame,
                                        &source_string) == Ok &&
                JS::GetSavedFrameLine(cx, nullptr, saved_frame, &line) == Ok &&
                JS::GetSavedFrameColumn(cx, nullptr, saved_frame, &column) ==
                    Ok;
            if (JS::GetSavedFrameParent(cx, nullptr, saved_frame,
                                        &saved_frame) != Ok) {
                // If we can't iterate, bail out and don't print source map info
                break;
            }

            if (!success) {
                continue;
            }

            if (!gjs_global_source_map_get(cx, registry, source_string,
                                           &consumer) ||
                !consumer) {
                log_exception_brief(cx);
                continue;  // no source map for this file
            }

            // build query obj for consumer
            JS::RootedObject input_obj{cx, JS_NewPlainObject(cx)};
            if (!input_obj ||
                !JS_DefineProperty(cx, input_obj, "line", line,
                                   JSPROP_ENUMERATE) ||
                !JS_DefineProperty(cx, input_obj, "column",
                                   column.oneOriginValue() - 1,
                                   JSPROP_ENUMERATE)) {
                log_exception_brief(cx);
                continue;
            }

            JS::RootedValue val{cx, JS::ObjectValue(*input_obj)};
            if (!JS::Call(cx, consumer, "originalPositionFor",
                          JS::HandleValueArray(val), &val)) {
                log_exception_brief(cx);
                continue;
            }
            JS::RootedObject rvalObj{cx, &val.toObject()};

            out << " -> ";

            if (!JS_GetProperty(cx, rvalObj, "name", &val)) {
                log_exception_brief(cx);
                continue;
            }
            if (val.isString()) {
                JS::UniqueChars name{gjs_string_to_utf8(cx, val)};
                if (name)
                    out << name.get() << "@";
                log_exception_brief(cx);
            }
            if (!JS_GetProperty(cx, rvalObj, "source", &val)) {
                log_exception_brief(cx);
                continue;
            }
            if (val.isString()) {
                JS::UniqueChars source{gjs_string_to_utf8(cx, val)};
                if (source)
                    out << source.get();
                log_exception_brief(cx);
            }
            if (!JS_GetProperty(cx, rvalObj, "line", &val)) {
                log_exception_brief(cx);
                continue;
            }
            if (val.isInt32()) {
                out << ":" << val.toInt32();
            }
            if (!JS_GetProperty(cx, rvalObj, "column", &val)) {
                log_exception_brief(cx);
                continue;
            }
            if (val.isInt32()) {
                out << ":" << val.toInt32() + 1;
            }
        }
        return out.str();
    }

    JS::RootedValue stack{cx};
    if (!JS_GetPropertyById(cx, exc, atoms.stack(), &stack) ||
        !stack.isString()) {
        log_exception_brief(cx);
        return {};
    }

    JS::RootedString str{cx, stack.toString()};
    bool is_empty;
    if (!JS_StringEqualsLiteral(cx, str, "", &is_empty) || is_empty) {
        log_exception_brief(cx);
        return {};
    }

    JS::UniqueChars utf8_stack{JS_EncodeStringToUTF8(cx, str)};
    if (!utf8_stack) {
        log_exception_brief(cx);
        return {};
    }

    out << '\n' << utf8_stack.get();
    return out.str();
}

// Helper function: format the file name, line number, and column number where a
// SyntaxError occurred.
static std::string format_syntax_error_location(JSContext* cx,
                                                JS::HandleObject exc) {
    const GjsAtoms& atoms = GjsContextPrivate::atoms(cx);

    JS::RootedValue property(cx);
    int32_t line = 0;
    if (JS_GetPropertyById(cx, exc, atoms.line_number(), &property)) {
        if (property.isInt32())
            line = property.toInt32();
    }
    log_exception_brief(cx);

    int32_t column = 0;
    if (JS_GetPropertyById(cx, exc, atoms.column_number(), &property)) {
        if (property.isInt32())
            column = property.toInt32();
    }
    log_exception_brief(cx);

    JS::UniqueChars utf8_filename;
    if (JS_GetPropertyById(cx, exc, atoms.file_name(), &property)) {
        if (property.isString()) {
            JS::RootedString str(cx, property.toString());
            utf8_filename = JS_EncodeStringToUTF8(cx, str);
        }
    }
    log_exception_brief(cx);

    std::ostringstream out;
    out << " @ ";
    if (utf8_filename)
        out << utf8_filename.get();
    else
        out << "<unknown>";
    out << ":" << line << ":" << column;
    return out.str();
}

using CauseSet = JS::GCHashSet<JSObject*, js::DefaultHasher<JSObject*>,
                               js::SystemAllocPolicy>;

static std::string format_exception_with_cause(
    JSContext* cx, JS::HandleObject exc_obj,
    JS::MutableHandle<CauseSet> seen_causes) {
    std::ostringstream out;
    const GjsAtoms& atoms = GjsContextPrivate::atoms(cx);

    out << format_exception_stack(cx, exc_obj);

    JS::RootedValue v_cause(cx);
    if (!JS_GetPropertyById(cx, exc_obj, atoms.cause(), &v_cause))
        log_exception_brief(cx);
    if (v_cause.isUndefined())
        return out.str();

    JS::RootedObject cause(cx);
    if (v_cause.isObject()) {
        cause = &v_cause.toObject();
        CauseSet::AddPtr entry = seen_causes.lookupForAdd(cause);
        if (entry)
            return out.str();  // cause has been printed already, ref cycle
        if (!seen_causes.add(entry, cause))
            return out.str();  // out of memory, just stop here
    }

    out << "\nCaused by: ";
    JS::RootedString exc_str(cx, exception_to_string(cx, v_cause));
    if (exc_str) {
        JS::UniqueChars utf8_exception = JS_EncodeStringToUTF8(cx, exc_str);
        if (utf8_exception)
            out << utf8_exception.get();
    }
    log_exception_brief(cx);

    if (v_cause.isObject())
        out << format_exception_with_cause(cx, cause, seen_causes);

    return out.str();
}

static std::string format_exception_log_message(JSContext* cx,
                                                JS::HandleValue exc,
                                                JS::HandleString message) {
    std::ostringstream out;

    if (message) {
        JS::UniqueChars utf8_message = JS_EncodeStringToUTF8(cx, message);
        log_exception_brief(cx);
        if (utf8_message)
            out << utf8_message.get() << ": ";
    }

    JS::RootedString exc_str(cx, exception_to_string(cx, exc));
    if (exc_str) {
        JS::UniqueChars utf8_exception = JS_EncodeStringToUTF8(cx, exc_str);
        if (utf8_exception)
            out << utf8_exception.get();
    }
    log_exception_brief(cx);

    if (!exc.isObject())
        return out.str();

    JS::RootedObject exc_obj(cx, &exc.toObject());
    const JSClass* syntax_error = js::ProtoKeyToClass(JSProto_SyntaxError);
    if (JS_InstanceOf(cx, exc_obj, syntax_error, nullptr)) {
        // We log syntax errors differently, because the stack for those
        // includes only the referencing module, but we want to print out the
        // file name, line number, and column number from the exception.
        // We assume that syntax errors have no cause property, and are not the
        // cause of other exceptions, so no recursion.
        out << format_syntax_error_location(cx, exc_obj)
            << format_exception_stack(cx, exc_obj);
        return out.str();
    }

    JS::Rooted<CauseSet> seen_causes(cx);
    seen_causes.putNew(exc_obj);
    out << format_exception_with_cause(cx, exc_obj, &seen_causes);
    return out.str();
}

/**
 * gjs_log_exception_full:
 * @cx: the #JSContext
 * @exc: the exception value to be logged
 * @message: a string to prepend to the log message
 * @level: the severity level at which to log the exception
 *
 * Currently, uses %G_LOG_LEVEL_WARNING if the exception is being printed after
 * being caught, and %G_LOG_LEVEL_CRITICAL if it was not caught by user code.
 */
void gjs_log_exception_full(JSContext* cx, JS::HandleValue exc,
                            JS::HandleString message, GLogLevelFlags level) {
    JS::AutoSaveExceptionState saved_exc(cx);
    std::string log_msg = format_exception_log_message(cx, exc, message);
    g_log(G_LOG_DOMAIN, level, "JS ERROR: %s", log_msg.c_str());
    saved_exc.restore();
}

/**
 * gjs_log_exception:
 * @cx: the #JSContext
 *
 * Logs the exception pending on @cx, if any, in response to an exception being
 * thrown that user code cannot catch or has already caught.
 *
 * Returns: %true if an exception was logged, %false if there was none pending.
 */
bool gjs_log_exception(JSContext* cx) {
    JS::RootedValue exc{cx};
    if (!JS_GetPendingException(cx, &exc))
        return false;

    JS_ClearPendingException(cx);

    gjs_log_exception_full(cx, exc, nullptr, G_LOG_LEVEL_WARNING);
    return true;
}

/**
 * gjs_log_exception_uncaught:
 * @cx: the #JSContext
 *
 * Logs the exception pending on @cx, if any, indicating an uncaught exception
 * in the running JS program.
 * (Currently, due to main loop boundaries, uncaught exceptions may not bubble
 * all the way back up to the top level, so this doesn't necessarily mean the
 * program exits with an error.)
 *
 * Returns: %true if an exception was logged, %false if there was none pending.
 */
bool gjs_log_exception_uncaught(JSContext* cx) {
    JS::RootedValue exc(cx);
    if (!JS_GetPendingException(cx, &exc))
        return false;

    JS_ClearPendingException(cx);

    gjs_log_exception_full(cx, exc, nullptr, G_LOG_LEVEL_CRITICAL);
    return true;
}

void gjs_gc_if_needed(JSContext* cx) {
#ifdef __linux__
    using std::chrono_literals::operator""us;

    // We initiate a GC if RSS has grown by this much. It is initialized to 0,
    // so currently we always do a full GC early.
    static uint64_t linux_rss_trigger;
    static GLib::MonotonicTime last_gc_check_time;

    // We rate limit GCs to at most one per 5 frames. One frame is 16666
    // microseconds (1000000/60)
    GLib::MonotonicTime now{GLib::MonotonicClock::now()};
    if (now - last_gc_check_time < 5 * 16666us)
        return;

    last_gc_check_time = now;

    Gjs::AutoChar contents;
    if (!g_file_get_contents("/proc/self/statm", contents.out(), nullptr,
                             nullptr)) {
        g_critical("Error reading contents of /proc/self/statm");
        return;
    }

    Gjs::StatmParseResult result = Gjs::parse_statm_file_rss(contents);
    if (result.isErr()) {
        std::string message{result.unwrapErr()};
        g_critical("%s", message.c_str());
        return;
    }
    uint64_t rss = result.unwrap();

    // Here we see if the RSS has grown by 25% since our last look; if so,
    // initiate a full compacting GC. In theory using RSS is bad if we get
    // swapped out, since we may be overzealous in GC, but on the other hand, if
    // swapping is going on, better to GC.
    if (rss > linux_rss_trigger) {
        linux_rss_trigger = std::min(UINT64_C(0xffff'ffff), rss + (rss / 4));
        JS::NonIncrementalGC(cx, JS::GCOptions::Shrink,
                             Gjs::GCReason::LINUX_RSS_TRIGGER);
    } else if (rss < (0.75 * linux_rss_trigger)) {
        // If we've shrunk back to 75%, lower the trigger to 25% above the
        // current value
        linux_rss_trigger = rss * 1.25;
    }
#else  // !__linux__
    (void)cx;
#endif
}

/**
 * gjs_maybe_gc:
 *
 * Low level version of gjs_context_maybe_gc().
 */
void gjs_maybe_gc(JSContext* cx) {
    JS_MaybeGC(cx);
    gjs_gc_if_needed(cx);
}

const char* gjs_explain_gc_reason(JS::GCReason reason) {
    if (JS::InternalGCReason(reason))
        return JS::ExplainGCReason(reason);

    static const char* reason_strings[] = {
        "RSS above threshold",     "GjsContext disposed", "Big Hammer hit",
        "gjs_context_gc() called", "Memory usage is low",
    };
    static_assert(G_N_ELEMENTS(reason_strings) == Gjs::GCReason::N_REASONS,
                  "Explanations must match the values in Gjs::GCReason");

    auto reason_ix = static_cast<size_t>(reason);
    auto first_firefox_ix =
        static_cast<size_t>(JS::GCReason::FIRST_FIREFOX_REASON);
    g_assert(reason_ix < first_firefox_ix + Gjs::GCReason::N_REASONS &&
             "Bad Gjs::GCReason");
    return reason_strings[reason_ix - first_firefox_ix];
}
