/*
 * Copyright (c) 2020, Matthew Olsson <matthewcolsson@gmail.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <AK/Function.h>
#include <LibJS/Heap/Heap.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/PrimitiveString.h>
#include <LibJS/Runtime/RegExpObject.h>
#include <LibJS/Runtime/Value.h>

namespace JS {

static Flags options_from(const String& flags, VM& vm, GlobalObject& global_object)
{
    bool g = false, i = false, m = false, s = false, u = false, y = false;
    Flags options {
        { (regex::ECMAScriptFlags)regex::AllFlags::Global }, // JS regexps are all 'global' by default as per our definition, but the "global" flag enables "stateful".
        {},
    };

    for (auto ch : flags) {
        switch (ch) {
        case 'g':
            if (g)
                vm.throw_exception<SyntaxError>(global_object, ErrorType::RegExpObjectRepeatedFlag, ch);
            g = true;
            options.effective_flags |= regex::ECMAScriptFlags::Global;
            options.declared_flags |= regex::ECMAScriptFlags::Global;
            break;
        case 'i':
            if (i)
                vm.throw_exception<SyntaxError>(global_object, ErrorType::RegExpObjectRepeatedFlag, ch);
            i = true;
            options.effective_flags |= regex::ECMAScriptFlags::Insensitive;
            options.declared_flags |= regex::ECMAScriptFlags::Insensitive;
            break;
        case 'm':
            if (m)
                vm.throw_exception<SyntaxError>(global_object, ErrorType::RegExpObjectRepeatedFlag, ch);
            m = true;
            options.effective_flags |= regex::ECMAScriptFlags::Multiline;
            options.declared_flags |= regex::ECMAScriptFlags::Multiline;
            break;
        case 's':
            if (s)
                vm.throw_exception<SyntaxError>(global_object, ErrorType::RegExpObjectRepeatedFlag, ch);
            s = true;
            options.effective_flags |= regex::ECMAScriptFlags::SingleLine;
            options.declared_flags |= regex::ECMAScriptFlags::SingleLine;
            break;
        case 'u':
            if (u)
                vm.throw_exception<SyntaxError>(global_object, ErrorType::RegExpObjectRepeatedFlag, ch);
            u = true;
            options.effective_flags |= regex::ECMAScriptFlags::Unicode;
            options.declared_flags |= regex::ECMAScriptFlags::Unicode;
            break;
        case 'y':
            if (y)
                vm.throw_exception<SyntaxError>(global_object, ErrorType::RegExpObjectRepeatedFlag, ch);
            y = true;
            // Now for the more interesting flag, 'sticky' actually unsets 'global', part of which is the default.
            options.effective_flags.reset_flag(regex::ECMAScriptFlags::Global);
            // "What's the difference between sticky and global, then", that's simple.
            // all the other flags imply 'global', and the "global" flag implies 'stateful';
            // however, the "sticky" flag does *not* imply 'global', only 'stateful'.
            options.effective_flags |= (regex::ECMAScriptFlags)regex::AllFlags::Internal_Stateful;
            options.effective_flags |= regex::ECMAScriptFlags::Sticky;
            options.declared_flags |= regex::ECMAScriptFlags::Sticky;
            break;
        default:
            vm.throw_exception<SyntaxError>(global_object, ErrorType::RegExpObjectBadFlag, ch);
            return options;
        }
    }

    return options;
}

RegExpObject* RegExpObject::create(GlobalObject& global_object, String pattern, String flags)
{
    return global_object.heap().allocate<RegExpObject>(global_object, pattern, flags, *global_object.regexp_prototype());
}

RegExpObject::RegExpObject(String pattern, String flags, Object& prototype)
    : Object(prototype)
    , m_pattern(pattern)
    , m_flags(flags)
    , m_active_flags(options_from(m_flags, this->vm(), this->global_object()))
    , m_regex(pattern, m_active_flags.effective_flags)
{
    if (m_regex.parser_result.error != regex::Error::NoError) {
        vm().throw_exception<SyntaxError>(global_object(), ErrorType::RegExpCompileError, m_regex.error_string());
    }
}

void RegExpObject::initialize(GlobalObject& global_object)
{
    auto& vm = this->vm();
    Object::initialize(global_object);

    define_native_property(vm.names.lastIndex, last_index, set_last_index, Attribute::Writable);
}

RegExpObject::~RegExpObject()
{
}

static RegExpObject* regexp_object_from(VM& vm, GlobalObject& global_object)
{
    auto* this_object = vm.this_value(global_object).to_object(global_object);
    if (!this_object)
        return nullptr;
    if (!is<RegExpObject>(this_object)) {
        vm.throw_exception<TypeError>(global_object, ErrorType::NotA, "RegExp");
        return nullptr;
    }
    return static_cast<RegExpObject*>(this_object);
}

JS_DEFINE_NATIVE_GETTER(RegExpObject::last_index)
{
    auto regexp_object = regexp_object_from(vm, global_object);
    if (!regexp_object)
        return {};

    return Value((unsigned)regexp_object->regex().start_offset);
}

JS_DEFINE_NATIVE_SETTER(RegExpObject::set_last_index)
{
    auto regexp_object = regexp_object_from(vm, global_object);
    if (!regexp_object)
        return;

    auto index = value.to_i32(global_object);
    if (vm.exception())
        return;

    if (index < 0)
        index = 0;

    regexp_object->regex().start_offset = index;
}

}