#include "Buffer.h"
#include <stdio.h>
#include "System.h"
#include "File.h"
#include "TextLoader.h"
#include <cassert>

Buffer::Buffer()
{
    piece_table = std::make_shared<PieceTable>();
    m_file_buffer = nullptr;
    m_file_buffer_size = 0u;
    m_eol_at_eof = true;
    m_line_endings = LineEndings::LF;
    m_encoding = Encoding::UTF_8;
    piece_table->encoding = m_encoding;
}

Buffer::~Buffer()
{
    if (m_file_buffer != nullptr)
    {
        free_file_buffer();
    }
}

bool Buffer::load_from_file(const char * filename)
{
    File file;
    if (!file.open(filename))
    {
        return false;
    }

    size_t file_size = file.get_size();
    if (file_size < 0)
    {
        return false;
    }

    m_file_buffer_size = ((unsigned long)file_size + System::page_size) & System::page_base_mask;
    m_file_buffer = (uint8_t *)System::alloc_pages(m_file_buffer_size >> System::page_size_log);
    if (m_file_buffer == NULL)
    {
        return false;
    }

    if (!file.read(m_file_buffer, file_size))
    {
        free_file_buffer();
        return false;
    }

    TextLoader text_loader;
    text_loader.load_buffer(m_file_buffer, file_size);

    piece_table = std::make_shared<PieceTable>();
    for (auto it = text_loader.begin(); it != text_loader.end(); it++)
    {
        auto next = it;
        next++;
        bool eol = next != text_loader.end();
        it->start[it->length] = PieceTable::INTERNAL_EOL;
        piece_table->append_initial_line_piece(it->start, it->length + 1u, eol);
    }

    m_eol_at_eof = text_loader.get_eol_at_eof();
    m_line_endings = text_loader.get_line_endings();
    m_encoding = text_loader.get_encoding();
    piece_table->encoding = m_encoding;

    return true;
}

bool Buffer::write_to_file(const char * filename)
{
    File file;
    if (!file.open(filename, true))
    {
        return false;
    }

    uint32_t bytes_written = 0u;
    for (auto piece = piece_table->start_piece->next;
         piece != piece_table->end_piece;
         piece = piece->next)
    {
        uint32_t length = piece->length;
        if (piece->eol())
        {
            length--;
        }
        if (!file.write(piece->start, length))
        {
            return false;
        }
        bytes_written += length;
        if (((piece->next != piece_table->end_piece) && piece->eol()) ||
            (m_eol_at_eof && bytes_written > 0u))
        {
            if (!file.write(LineEndings::spans[m_line_endings]))
            {
                return false;
            }
            bytes_written += LineEndings::spans[m_line_endings].length;
        }
    }

    return true;
}

void Buffer::free_file_buffer()
{
    System::free_pages(m_file_buffer, m_file_buffer_size >> System::page_size_log);
    m_file_buffer = nullptr;
    m_file_buffer_size = 0u;
}