/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * Copyright (c) 2022, the SerenityOS developers.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/HashMap.h>
#include <LibCore/DateTime.h>
#include <LibCore/FileWatcher.h>
#include <LibGUI/Model.h>
#include <string.h>
#include <sys/stat.h>
#include <time.h>

namespace GUI {

class FileSystemModel
    : public Model
    , public Weakable<FileSystemModel> {
    friend struct Node;

public:
    enum Mode {
        Invalid,
        DirectoriesOnly,
        FilesAndDirectories
    };

    enum Column {
        Icon = 0,
        Name,
        Size,
        User,
        Group,
        Permissions,
        ModificationTime,
        Inode,
        SymlinkTarget,
        __Count,
    };

    struct Node {
        ~Node() = default;

        DeprecatedString name;
        DeprecatedString symlink_target;
        size_t size { 0 };
        mode_t mode { 0 };
        uid_t uid { 0 };
        gid_t gid { 0 };
        ino_t inode { 0 };
        time_t mtime { 0 };
        bool is_accessible_directory { false };

        size_t total_size { 0 };

        mutable RefPtr<Gfx::Bitmap> thumbnail;
        bool is_directory() const { return S_ISDIR(mode); }
        bool is_symlink_to_directory() const;
        bool is_executable() const { return mode & (S_IXUSR | S_IXGRP | S_IXOTH); }

        bool is_selected() const { return m_selected; }
        void set_selected(bool selected);

        bool has_error() const { return m_error != 0; }
        int error() const { return m_error; }
        char const* error_string() const { return strerror(m_error); }

        bool can_delete_or_move() const;

        DeprecatedString full_path() const;

    private:
        friend class FileSystemModel;

        explicit Node(FileSystemModel& model)
            : m_model(model)
        {
        }

        FileSystemModel& m_model;

        Node* m_parent { nullptr };
        Vector<NonnullOwnPtr<Node>> m_children;
        mutable Optional<bool> m_can_delete_or_move;
        bool m_has_traversed { false };

        bool m_selected { false };

        int m_error { 0 };
        bool m_parent_of_root { false };

        ModelIndex index(int column) const;
        void traverse_if_needed();
        void reify_if_needed();
        bool fetch_data(DeprecatedString const& full_path, bool is_root);

        OwnPtr<Node> create_child(DeprecatedString const& child_name);
    };

    static NonnullRefPtr<FileSystemModel> create(DeprecatedString root_path = "/", Mode mode = Mode::FilesAndDirectories)
    {
        return adopt_ref(*new FileSystemModel(root_path, mode));
    }
    virtual ~FileSystemModel() override = default;

    DeprecatedString root_path() const { return m_root_path; }
    void set_root_path(DeprecatedString);
    DeprecatedString full_path(ModelIndex const&) const;
    ModelIndex index(DeprecatedString path, int column) const;

    void update_node_on_selection(ModelIndex const&, bool const);
    ModelIndex m_previously_selected_index {};

    Node const& node(ModelIndex const& index) const;

    Function<void(int done, int total)> on_thumbnail_progress;
    Function<void()> on_complete;
    Function<void(int error, char const* error_string)> on_directory_change_error;
    Function<void(int error, char const* error_string)> on_rename_error;
    Function<void(DeprecatedString const& old_name, DeprecatedString const& new_name)> on_rename_successful;
    Function<void()> on_root_path_removed;

    virtual int tree_column() const override { return Column::Name; }
    virtual int row_count(ModelIndex const& = ModelIndex()) const override;
    virtual int column_count(ModelIndex const& = ModelIndex()) const override;
    virtual DeprecatedString column_name(int column) const override;
    virtual Variant data(ModelIndex const&, ModelRole = ModelRole::Display) const override;
    virtual ModelIndex parent_index(ModelIndex const&) const override;
    virtual ModelIndex index(int row, int column = 0, ModelIndex const& parent = ModelIndex()) const override;
    virtual StringView drag_data_type() const override { return "text/uri-list"sv; }
    virtual bool accepts_drag(ModelIndex const&, Vector<DeprecatedString> const& mime_types) const override;
    virtual bool is_column_sortable(int column_index) const override { return column_index != Column::Icon; }
    virtual bool is_editable(ModelIndex const&) const override;
    virtual bool is_searchable() const override { return true; }
    virtual void set_data(ModelIndex const&, Variant const&) override;
    virtual Vector<ModelIndex> matches(StringView, unsigned = MatchesFlag::AllMatching, ModelIndex const& = ModelIndex()) override;
    virtual void invalidate() override;

    static DeprecatedString timestamp_string(time_t timestamp)
    {
        return Core::DateTime::from_timestamp(timestamp).to_deprecated_string();
    }

    bool should_show_dotfiles() const { return m_should_show_dotfiles; }
    void set_should_show_dotfiles(bool);

    Optional<Vector<DeprecatedString>> allowed_file_extensions() const { return m_allowed_file_extensions; }
    void set_allowed_file_extensions(Optional<Vector<DeprecatedString>> const& allowed_file_extensions);

private:
    FileSystemModel(DeprecatedString root_path, Mode);

    DeprecatedString name_for_uid(uid_t) const;
    DeprecatedString name_for_gid(gid_t) const;

    Optional<Node const&> node_for_path(DeprecatedString const&) const;

    HashMap<uid_t, DeprecatedString> m_user_names;
    HashMap<gid_t, DeprecatedString> m_group_names;

    bool fetch_thumbnail_for(Node const& node);
    GUI::Icon icon_for(Node const& node) const;

    void handle_file_event(Core::FileWatcherEvent const& event);

    DeprecatedString m_root_path;
    Mode m_mode { Invalid };
    OwnPtr<Node> m_root { nullptr };

    unsigned m_thumbnail_progress { 0 };
    unsigned m_thumbnail_progress_total { 0 };

    Optional<Vector<DeprecatedString>> m_allowed_file_extensions;

    bool m_should_show_dotfiles { false };

    RefPtr<Core::FileWatcher> m_file_watcher;
};

}