// Buffer.cpp

#include "Buffer.h"

using namespace std;

void Buffer::display() const
{
    int ix_stop_line = ix_top_line_ + window_height_;
    auto itr = itr_top_line_;
    for (int i = ix_top_line_; i < ix_stop_line; ++i) {
        if (i <= ls_lines_.size()) {
            if (i == ix_current_line_)
                cout << '>';
            else
                cout << ' ';
            cout << std::setw(5) << i+1;
            if (i < ls_lines_.size()) {
                cout << "  " << *itr;
                ++itr;
            }
        }
        cout << endl;
    }
}

void Buffer::erase()
{
    if (ix_current_line_ < ls_lines_.size()) {
        itr_current_line_ = ls_lines_.erase(itr_current_line_);
        if (ix_top_line_ == ix_current_line_)
            itr_top_line_ = itr_current_line_;
    }
}

void Buffer::insert(const string & new_line)
{
    ls_lines_.insert(itr_current_line_, new_line);
    ++ix_current_line_;
    if (itr_top_line_ == itr_current_line_) {
        // insertion was at the top
        --itr_top_line_;
    }
    if (ix_current_line_ == ix_top_line_ + window_height_) {
        // insertion was at the bottom
        ++ix_top_line_;
        ++itr_top_line_;
    }
}

void Buffer::move_to_next_line()
{
    if (ix_current_line_ < ls_lines_.size()) {
        ++ix_current_line_;
        ++itr_current_line_;
        // check if window needs to be scrolled down
        if (ix_current_line_ >= ix_top_line_ + window_height_) {
            ++ix_top_line_;
            ++itr_top_line_;
        }
    }
}

void Buffer::move_to_previous_line()
{
    if (ix_current_line_ > 0) {
        --ix_current_line_;
        --itr_current_line_;
        // check if window needs to be scrolled up
        if (ix_current_line_ < ix_top_line_) {
            --ix_top_line_;
            --itr_top_line_;
        }
    }
}

bool Buffer::open(const string & new_file_name)
{
    std::ifstream file(new_file_name);
    if (!file)
        return false;

    ls_lines_.clear();

    string line;
    while (getline(file, line))
        ls_lines_.push_back(line);

    file_name_ = new_file_name;
    ix_current_line_ = ix_top_line_ = 0;
    itr_current_line_ = itr_top_line_ = ls_lines_.begin();
    return true;
}

bool Buffer::save(const string & new_file_name)
{
    std::ofstream file(new_file_name);
    if (!file)
        return false;

    file_name_ = new_file_name;
    for (const string & line : ls_lines_)
        file << line << endl;
    return true;
}