#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <algorithm>
#include <fstream>
#include <sstream>
#include "history.hpp"
#include "appContext.hpp"

using namespace std;
using namespace knacki::cd;

static std::string RelativePathToAbsolute(const string &path)
{
    if (path[0] == '/')
        return path;
    char *p = realpath(path.c_str(), nullptr);
    // FIXME error check
    string pathResult(p);
    free(p);
    return pathResult;
}

HistoryEntry::HistoryEntry(PTR_TYPE i, const string &e): path(e), index(i)
{}

HistoryEntry::HistoryEntry(const HistoryEntry &o): path(o.path), index(o.index)
{}

HistoryEntry &HistoryEntry::operator=(const HistoryEntry &o)
{
    path = o.path;
    index = o.index;
    return *this;
}

const std::string &HistoryEntry::GetPath() const
{ return path; }

PTR_TYPE HistoryEntry::GetIndex() const
{ return index; }

History::History(const string &path): current(-1), prev(-1)
{
    std::ifstream file(path, fstream::in | fstream::binary);
    Read(file);
}

HistoryRW::HistoryRW(const string &_path): History(_path), path(_path)
{}

const std::vector<HistoryEntry> &History::GetEntries() const
{ return hist; }

const HistoryEntry *History::GetHistoryEntry(PTR_TYPE index) const
{
    for (const HistoryEntry &i: GetEntries())
        if (i.GetIndex() == index)
            return &i;
    return nullptr;
}

void History::Read(std::istream &file)
{
    PTR_TYPE current = -1;
    PTR_TYPE prev = -1;
    unsigned int histIndex =0;
    std::streamsize size;
    char *buf = nullptr;
    std::streamsize bufSize = 0;

    hist.clear();
    if (!file.good() && errno != ENOENT)
        throw IOError(strerror(errno));
    file.seekg(0);
    if (sizeof(prev) != file.readsome((char *)(&prev), sizeof(prev)))
        return;
    if (sizeof(current) != file.readsome((char *)(&current), sizeof(current)))
        return;
    while (file.good())
    {
        if (sizeof(size) != file.readsome((char*)(&size), sizeof(size)))
            break;
        if (size > bufSize)
        {
            delete[] buf;
            buf = new char[size]();
            bufSize = size;
        }
        if (size != file.readsome(buf, size))
            break;
        const size_t lastIndex = ++histIndex;
        hist.push_back(HistoryEntry(lastIndex, string(buf, size)));
        if (current != -1)
            if (!--current)
                this->current = lastIndex;
        if (prev != -1)
            if (!--prev)
                this->prev = lastIndex;
    }
    delete []buf;
    if (this->current == -1)
        this->current = hist.back().GetIndex();
}

void HistoryRW::Write()
{
    size_t written = 0;

    std::ofstream file(path, fstream::in | fstream::out | fstream::binary | fstream::trunc);
    if (!file.good())
        throw IOError(strerror(errno));
    file.write((char*)(&prev), sizeof(prev));
    file.write((char*)(&current), sizeof(current));
    for (HistoryEntry i: hist)
    {
        const size_t pathLen = i.GetPath().length();
        file.write((char*)(&pathLen), sizeof(pathLen));
        written += sizeof(pathLen);
        file.write(i.GetPath().c_str(), sizeof(*(i.GetPath().c_str())) * i.GetPath().size());
        written += sizeof(*(i.GetPath().c_str())) * i.GetPath().size();
    }
}

bool HistoryRW::AppendCwd()
{
    char *cwd = get_current_dir_name();
    const bool result = Append(cwd);
    free(cwd);
    return result;
}

bool HistoryRW::Append(const HistoryEntry &ent)
{
    const HistoryEntry *e = GetHistoryEntry(ent.GetIndex());
    if (e)
    {
        // Juste move ptr
        if (current != e->GetIndex())
        {
            prev = current;
            current = e->GetIndex();
            return true;
        }
        else
            return false;
    }
    return Append(ent.GetPath());
}

void HistoryRW::TruncateAfter(PTR_TYPE pos)
{
    while (!hist.empty() && hist.back().GetIndex() > pos)
        hist.pop_back();
}

bool HistoryRW::Append(const std::string &path)
{
    if (current != -1)
    {
        const HistoryEntry *ent = GetHistoryEntry(current);
        if (ent && ent->GetPath() == path)
            return false;
        TruncateAfter(current);
    }
    const size_t lastIndex = hist.size() +1;
    hist.push_back(HistoryEntry(lastIndex, path));
    prev = current;
    current = lastIndex;
    return true;
}

bool HistoryRW::Flush()
{
    if (hist.empty())
        return false;
    hist.clear();
    current = prev = -1;
    return true;
}

bool History::IsPrevious(const HistoryEntry &e) const
{ return prev != -1 && prev == e.GetIndex(); }

bool History::IsCurrent(const HistoryEntry &e) const
{ return current != -1 && current == e.GetIndex(); }

const HistoryEntry *History::GetNextWorkingDirectory(const AppContext &app) const
{
    const string dest = app.GetArgs().pushArg;
    if (dest == "-")
    {
        const char *buf = nullptr;
        if (prev != -1)
        {
            const HistoryEntry *e = GetHistoryEntry(prev);
            if (e)
                return new HistoryEntry(*e);
        }
        if ((buf = getenv("OLDPWD")))
            return new HistoryEntry(hist.size() +1, buf);
        else
            return nullptr;
    }
    else if (dest[0] == '-' || dest[0] == '+')
    {
        stringstream eventId(dest.c_str() +1);
        long eventIdLong = 0;
        eventId >> eventIdLong;
        eventIdLong = (current > -1 ? current : 0) +(eventIdLong * (dest[0] == '-' ? -1 : 1));
        const HistoryEntry *ent = GetHistoryEntry(eventIdLong);
        return ent ? new HistoryEntry(*ent) : nullptr;
    }
    const string absDest = RelativePathToAbsolute(dest);
    return new HistoryEntry(hist.size() +1, absDest);
}