#pragma once

#include <algorithm>
#include <string>
#include <vector>

#include "key_event.h"

// The help panel (issue #69, docs/milestones/U1.md): Fn+h on any screen lists the keys that work
// there. Every App says what its keys are in the state it's in; nothing on a screen names keys.
namespace roro {

// One line of the panel: a key (or keys) and what it does. A line with no action is a heading.
struct KeyHelp {
    const char* keys;
    const char* action;
};


// The panel itself: what it lists, and how far it's scrolled. The keys it takes while open are the
// arrows; any other key closes it, and none reaches the App.
class HelpModel {
   public:
    explicit HelpModel(int visibleRows = 8) : visible_(visibleRows) {}

    void open(const std::string& title, std::vector<KeyHelp> rows) {
        title_ = title;
        rows_ = std::move(rows);
        top_ = 0;
        open_ = true;
    }
    void close() {
        open_ = false;
        rows_.clear();
        rows_.shrink_to_fit();  // nothing is kept while it's closed
    }
    bool isOpen() const { return open_; }

    void onKey(const KeyEvent& e) {
        int last = std::max(0, static_cast<int>(rows_.size()) - visible_);
        switch (e.key) {
            case Key::Up: top_ = std::max(0, top_ - 1); break;
            case Key::Down: top_ = std::min(last, top_ + 1); break;
            case Key::Left: top_ = std::max(0, top_ - visible_); break;
            case Key::Right: top_ = std::min(last, top_ + visible_); break;
            default: close(); break;
        }
    }

    const std::string& title() const { return title_; }
    const std::vector<KeyHelp>& rows() const { return rows_; }
    int top() const { return top_; }
    int visibleRows() const { return visible_; }

   private:
    std::string title_;
    std::vector<KeyHelp> rows_;
    int top_ = 0;
    int visible_;
    bool open_ = false;
};

}  // namespace roro