/*
 * Copyright (c) 2021, Itamar S. <itamar8910@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 "ParserAutoComplete.h"
#include <AK/Assertions.h>
#include <AK/HashTable.h>
#include <LibCpp/AST.h>
#include <LibCpp/Lexer.h>
#include <LibCpp/Parser.h>
#include <LibCpp/Preprocessor.h>
#include <LibRegex/Regex.h>
#include <Userland/DevTools/HackStudio/LanguageServers/ClientConnection.h>

namespace LanguageServers::Cpp {

ParserAutoComplete::ParserAutoComplete(ClientConnection& connection, const FileDB& filedb)
    : AutoCompleteEngine(connection, filedb)
{
}

const ParserAutoComplete::DocumentData* ParserAutoComplete::get_or_create_document_data(const String& file)
{
    auto absolute_path = filedb().to_absolute_path(file);
    if (!m_documents.contains(absolute_path)) {
        set_document_data(absolute_path, create_document_data_for(absolute_path));
    }
    return get_document_data(absolute_path);
}

const ParserAutoComplete::DocumentData* ParserAutoComplete::get_document_data(const String& file) const
{
    auto absolute_path = filedb().to_absolute_path(file);
    auto document_data = m_documents.get(absolute_path);
    VERIFY(document_data.has_value());
    return document_data.value();
}

OwnPtr<ParserAutoComplete::DocumentData> ParserAutoComplete::create_document_data_for(const String& file)
{
    auto document = filedb().get_or_create_from_filesystem(file);
    if (!document)
        return {};
    auto content = document->text();
    auto document_data = create_document_data(document->text(), file);
    auto root = document_data->parser().parse();
    for (auto& path : document_data->preprocessor().included_paths()) {
        get_or_create_document_data(document_path_from_include_path(path));
    }
#ifdef CPP_LANGUAGE_SERVER_DEBUG
    root->dump(0);
#endif

    update_declared_symbols(*document_data);

    return document_data;
}

void ParserAutoComplete::set_document_data(const String& file, OwnPtr<DocumentData>&& data)
{
    m_documents.set(filedb().to_absolute_path(file), move(data));
}

Vector<GUI::AutocompleteProvider::Entry> ParserAutoComplete::get_suggestions(const String& file, const GUI::TextPosition& autocomplete_position)
{
    Cpp::Position position { autocomplete_position.line(), autocomplete_position.column() > 0 ? autocomplete_position.column() - 1 : 0 };

    dbgln_if(CPP_LANGUAGE_SERVER_DEBUG, "ParserAutoComplete position {}:{}", position.line, position.column);

    const auto* document_ptr = get_or_create_document_data(file);
    if (!document_ptr)
        return {};

    const auto& document = *document_ptr;
    auto node = document.parser().node_at(position);
    if (!node) {
        dbgln_if(CPP_LANGUAGE_SERVER_DEBUG, "no node at position {}:{}", position.line, position.column);
        return {};
    }

    if (node->is_identifier()) {
        if (is_property(*node)) {
            return autocomplete_property(document, (MemberExpression&)(*node->parent()), document.parser().text_of_node(*node));
        }

        return autocomplete_name(document, *node, document.parser().text_of_node(*node));
    }

    if (is_empty_property(document, *node, position)) {
        VERIFY(node->parent()->is_member_expression());
        return autocomplete_property(document, (MemberExpression&)(*node->parent()), "");
    }

    String partial_text = String::empty();
    auto containing_token = document.parser().token_at(position);
    if (containing_token.has_value()) {
        partial_text = document.parser().text_of_token(containing_token.value());
    }

    return autocomplete_name(document, *node, partial_text.view());
}

NonnullRefPtrVector<Declaration> ParserAutoComplete::get_available_declarations(const DocumentData& document, const ASTNode& node) const
{
    const Cpp::ASTNode* current = &node;
    NonnullRefPtrVector<Declaration> available_declarations;
    while (current) {
        available_declarations.append(current->declarations());
        current = current->parent();
    }

    available_declarations.append(get_global_declarations_including_headers(document));
    return available_declarations;
}

Vector<GUI::AutocompleteProvider::Entry> ParserAutoComplete::autocomplete_name(const DocumentData& document, const ASTNode& node, const String& partial_text) const
{
    auto available_declarations = get_available_declarations(document, node);
    Vector<StringView> available_names;
    auto add_name = [&available_names](auto& name) {
        if (name.is_null() || name.is_empty())
            return;
        if (!available_names.contains_slow(name))
            available_names.append(name);
    };
    for (auto& decl : available_declarations) {
        if (decl.filename() == node.filename() && decl.start().line > node.start().line)
            continue;
        if (decl.is_variable_or_parameter_declaration()) {
            add_name(((Cpp::VariableOrParameterDeclaration&)decl).m_name);
        }
        if (decl.is_struct_or_class()) {
            add_name(((Cpp::StructOrClassDeclaration&)decl).m_name);
        }
        if (decl.is_function()) {
            add_name(((Cpp::FunctionDeclaration&)decl).m_name);
        }
    }

    Vector<GUI::AutocompleteProvider::Entry> suggestions;
    for (auto& name : available_names) {
        if (name.starts_with(partial_text)) {
            suggestions.append({ name.to_string(), partial_text.length(), GUI::AutocompleteProvider::CompletionKind::Identifier });
        }
    }

    for (auto& preprocessor_name : document.parser().definitions().keys()) {
        if (preprocessor_name.starts_with(partial_text)) {
            suggestions.append({ preprocessor_name.to_string(), partial_text.length(), GUI::AutocompleteProvider::CompletionKind::PreprocessorDefinition });
        }
    }

    return suggestions;
}

Vector<GUI::AutocompleteProvider::Entry> ParserAutoComplete::autocomplete_property(const DocumentData& document, const MemberExpression& parent, const String partial_text) const
{
    auto type = type_of(document, *parent.m_object);
    if (type.is_null()) {
        dbgln_if(CPP_LANGUAGE_SERVER_DEBUG, "Could not infer type of object");
        return {};
    }

    Vector<GUI::AutocompleteProvider::Entry> suggestions;
    for (auto& prop : properties_of_type(document, type)) {
        if (prop.name.starts_with(partial_text)) {
            suggestions.append({ prop.name, partial_text.length(), GUI::AutocompleteProvider::CompletionKind::Identifier });
        }
    }
    return suggestions;
}

bool ParserAutoComplete::is_property(const ASTNode& node) const
{
    if (!node.parent()->is_member_expression())
        return false;

    auto& parent = (MemberExpression&)(*node.parent());
    return parent.m_property.ptr() == &node;
}

bool ParserAutoComplete::is_empty_property(const DocumentData& document, const ASTNode& node, const Position& autocomplete_position) const
{
    if (!node.parent()->is_member_expression())
        return false;
    auto previous_token = document.parser().token_at(autocomplete_position);
    if (!previous_token.has_value())
        return false;
    return previous_token.value().type() == Token::Type::Dot;
}

String ParserAutoComplete::type_of_property(const DocumentData& document, const Identifier& identifier) const
{
    auto& parent = (const MemberExpression&)(*identifier.parent());
    auto properties = properties_of_type(document, type_of(document, *parent.m_object));
    for (auto& prop : properties) {
        if (prop.name == identifier.m_name)
            return prop.type->m_name->full_name();
    }
    return {};
}

String ParserAutoComplete::type_of_variable(const Identifier& identifier) const
{
    const ASTNode* current = &identifier;
    while (current) {
        for (auto& decl : current->declarations()) {
            if (decl.is_variable_or_parameter_declaration()) {
                auto& var_or_param = (VariableOrParameterDeclaration&)decl;
                if (var_or_param.m_name == identifier.m_name) {
                    return var_or_param.m_type->m_name->full_name();
                }
            }
        }
        current = current->parent();
    }
    return {};
}

String ParserAutoComplete::type_of(const DocumentData& document, const Expression& expression) const
{
    if (expression.is_member_expression()) {
        auto& member_expression = (const MemberExpression&)expression;
        if (member_expression.m_property->is_identifier())
            return type_of_property(document, static_cast<const Identifier&>(*member_expression.m_property));
        return {};
    }

    const Identifier* identifier { nullptr };
    if (expression.is_name()) {
        identifier = static_cast<const Name&>(expression).m_name.ptr();
    } else if (expression.is_identifier()) {
        identifier = &static_cast<const Identifier&>(expression);
    } else {
        dbgln("expected identifier or name, got: {}", expression.class_name());
        VERIFY_NOT_REACHED(); // TODO
    }
    VERIFY(identifier);
    if (is_property(*identifier))
        return type_of_property(document, *identifier);

    return type_of_variable(*identifier);
}

Vector<ParserAutoComplete::PropertyInfo> ParserAutoComplete::properties_of_type(const DocumentData& document, const String& type) const
{
    auto declarations = get_global_declarations_including_headers(document);
    Vector<PropertyInfo> properties;
    for (auto& decl : declarations) {
        if (!decl.is_struct_or_class())
            continue;
        auto& struct_or_class = (StructOrClassDeclaration&)decl;
        if (struct_or_class.m_name != type)
            continue;
        for (auto& member : struct_or_class.m_members) {
            properties.append({ member.m_name, member.m_type });
        }
    }
    return properties;
}

NonnullRefPtrVector<Declaration> ParserAutoComplete::get_global_declarations_including_headers(const DocumentData& document) const
{
    NonnullRefPtrVector<Declaration> declarations;
    for (auto& include : document.preprocessor().included_paths()) {
        document_path_from_include_path(include);
        auto included_document = get_document_data(document_path_from_include_path(include));
        if (!included_document)
            continue;
        declarations.append(get_global_declarations_including_headers(*included_document));
    }

    declarations.append(get_global_declarations(*document.parser().root_node()));

    return declarations;
}

NonnullRefPtrVector<Declaration> ParserAutoComplete::get_global_declarations(const ASTNode& node) const
{
    NonnullRefPtrVector<Declaration> declarations;

    for (auto& decl : node.declarations()) {
        declarations.append(decl);
        if (decl.is_namespace()) {
            declarations.append(get_global_declarations(decl));
        }
    }

    return declarations;
}

String ParserAutoComplete::document_path_from_include_path(const StringView& include_path) const
{

    static Regex<PosixExtended> library_include("<(.+)>");
    static Regex<PosixExtended> user_defined_include("\"(.+)\"");

    auto document_path_for_library_include = [&](const StringView& include_path) -> String {
        RegexResult result;
        if (!library_include.search(include_path, result))
            return {};

        auto path = result.capture_group_matches.at(0).at(0).view.u8view();
        return String::formatted("/usr/include/{}", path);
    };

    auto document_path_for_user_defined_include = [&](const StringView& include_path) -> String {
        RegexResult result;
        if (!user_defined_include.search(include_path, result))
            return {};

        return result.capture_group_matches.at(0).at(0).view.u8view();
    };

    auto result = document_path_for_library_include(include_path);
    if (result.is_null())
        result = document_path_for_user_defined_include(include_path);

    return result;
}

void ParserAutoComplete::on_edit(const String& file)
{
    set_document_data(file, create_document_data_for(file));
}

void ParserAutoComplete::file_opened([[maybe_unused]] const String& file)
{
    set_document_data(file, create_document_data_for(file));
}

Optional<GUI::AutocompleteProvider::ProjectLocation> ParserAutoComplete::find_declaration_of(const String& file_name, const GUI::TextPosition& identifier_position)
{
    const auto* document_ptr = get_or_create_document_data(file_name);
    if (!document_ptr)
        return {};

    const auto& document = *document_ptr;
    auto node = document.parser().node_at(Cpp::Position { identifier_position.line(), identifier_position.column() });
    if (!node) {
        dbgln_if(CPP_LANGUAGE_SERVER_DEBUG, "no node at position {}:{}", identifier_position.line(), identifier_position.column());
        return {};
    }
    auto decl = find_declaration_of(document, *node);
    if (decl)
        return GUI::AutocompleteProvider::ProjectLocation { decl->filename(), decl->start().line, decl->start().column };

    return find_preprocessor_definition(document, identifier_position);
}

Optional<GUI::AutocompleteProvider::ProjectLocation> ParserAutoComplete::find_preprocessor_definition(const DocumentData& document, const GUI::TextPosition& text_position)
{
    Position cpp_position { text_position.line(), text_position.column() };

    // Search for a replaced preprocessor token that intersects with text_position
    for (auto& replaced_token : document.parser().replaced_preprocessor_tokens()) {
        if (replaced_token.token.start() > cpp_position)
            continue;
        if (replaced_token.token.end() < cpp_position)
            continue;

        return GUI::AutocompleteProvider::ProjectLocation { replaced_token.preprocessor_value.filename, replaced_token.preprocessor_value.line, replaced_token.preprocessor_value.column };
    }
    return {};
}

struct TargetDeclaration {
    enum Type {
        Variable,
        Type,
        Function,
        Property
    } type;
    String name;
};

static Optional<TargetDeclaration> get_target_declaration(const ASTNode& node)
{
    dbgln("get_target_declaration");
    if (!node.is_identifier()) {
        dbgln_if(CPP_LANGUAGE_SERVER_DEBUG, "node is not an identifier");
        return {};
    }

    const ASTNode* n = &node;
    while (n) {
        dbgln("{}", n->class_name());
        n = n->parent();
    }

    String name = static_cast<const Identifier&>(node).m_name;

    if ((node.parent() && node.parent()->is_function_call()) || (node.parent()->is_name() && node.parent()->parent() && node.parent()->parent()->is_function_call()))
        return TargetDeclaration { TargetDeclaration::Type::Function, name };

    if ((node.parent() && node.parent()->is_type()) || (node.parent()->is_name() && node.parent()->parent() && node.parent()->parent()->is_type()))
        return TargetDeclaration { TargetDeclaration::Type::Type, name };

    if ((node.parent() && node.parent()->is_member_expression()))
        return TargetDeclaration { TargetDeclaration::Type::Property, name };

    return TargetDeclaration { TargetDeclaration::Type::Variable, name };
}

RefPtr<Declaration> ParserAutoComplete::find_declaration_of(const DocumentData& document_data, const ASTNode& node) const
{
    dbgln_if(CPP_LANGUAGE_SERVER_DEBUG, "find_declaration_of: {} ({})", document_data.parser().text_of_node(node), node.class_name());
    auto target_decl = get_target_declaration(node);
    if (!target_decl.has_value())
        return {};

    auto declarations = get_available_declarations(document_data, node);
    for (auto& decl : declarations) {
        if (decl.is_function() && target_decl.value().type == TargetDeclaration::Function) {
            if (((Cpp::FunctionDeclaration&)decl).m_name == target_decl.value().name)
                return decl;
        }
        if (decl.is_variable_or_parameter_declaration() && target_decl.value().type == TargetDeclaration::Variable) {
            if (((Cpp::VariableOrParameterDeclaration&)decl).m_name == target_decl.value().name)
                return decl;
        }

        if (decl.is_struct_or_class() && target_decl.value().type == TargetDeclaration::Property) {
            // TODO: Also check that the type of the struct/class matches (not just the property name)
            for (auto& member : ((Cpp::StructOrClassDeclaration&)decl).m_members) {
                VERIFY(node.is_identifier());
                if (member.m_name == target_decl.value().name) {
                    return member;
                }
            }
        }

        if (decl.is_struct_or_class() && target_decl.value().type == TargetDeclaration::Type) {
            if (((Cpp::StructOrClassDeclaration&)decl).m_name == target_decl.value().name)
                return decl;
        }
    }
    return {};
}

void ParserAutoComplete::update_declared_symbols(const DocumentData& document)
{
    Vector<GUI::AutocompleteProvider::Declaration> declarations;

    for (auto& decl : get_global_declarations(*document.parser().root_node())) {
        declarations.append({ decl.name(), { document.filename(), decl.start().line, decl.start().column }, type_of_declaration(decl), scope_of_declaration(decl) });
    }

    for (auto& definition : document.preprocessor().definitions()) {
        declarations.append({ definition.key, { document.filename(), definition.value.line, definition.value.column }, GUI::AutocompleteProvider::DeclarationType::PreprocessorDefinition, {} });
    }

    set_declarations_of_document(document.filename(), move(declarations));
}

GUI::AutocompleteProvider::DeclarationType ParserAutoComplete::type_of_declaration(const Declaration& decl)
{
    if (decl.is_struct())
        return GUI::AutocompleteProvider::DeclarationType::Struct;
    if (decl.is_class())
        return GUI::AutocompleteProvider::DeclarationType::Class;
    if (decl.is_function())
        return GUI::AutocompleteProvider::DeclarationType::Function;
    if (decl.is_variable_declaration())
        return GUI::AutocompleteProvider::DeclarationType::Variable;
    return GUI::AutocompleteProvider::DeclarationType::Variable;
}

OwnPtr<ParserAutoComplete::DocumentData> ParserAutoComplete::create_document_data(String&& text, const String& filename)
{
    auto document_data = make<DocumentData>();
    document_data->m_filename = move(filename);
    document_data->m_text = move(text);
    document_data->m_preprocessor = make<Preprocessor>(document_data->m_filename, document_data->text());
    document_data->preprocessor().set_ignore_unsupported_keywords(true);
    document_data->preprocessor().process();

    Preprocessor::Definitions all_definitions;
    for (auto item : document_data->preprocessor().definitions())
        all_definitions.set(move(item.key), move(item.value));

    for (auto include : document_data->preprocessor().included_paths()) {
        auto included_document = get_or_create_document_data(document_path_from_include_path(include));
        if (!included_document)
            continue;
        for (auto item : included_document->parser().definitions())
            all_definitions.set(move(item.key), move(item.value));
    }

    document_data->m_parser = make<Parser>(document_data->preprocessor().processed_text(), filename, move(all_definitions));
    return document_data;
}

String ParserAutoComplete::scope_of_declaration(const Declaration& decl)
{

    auto parent = decl.parent();
    if (!parent)
        return {};

    if (!parent->is_declaration())
        return {};

    auto& parent_decl = static_cast<Declaration&>(*parent);

    if (parent_decl.is_namespace()) {
        auto& containing_namespace = static_cast<NamespaceDeclaration&>(parent_decl);
        auto scope_of_parent = scope_of_declaration(parent_decl);
        if (scope_of_parent.is_null())
            return containing_namespace.m_name;
        return String::formatted("{}::{}", scope_of_parent, containing_namespace.m_name);
    }

    return {};
}

}