/*
    Copyright© 2021 John Sennesael

    UsenetSearch is Free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    UsenetSearch is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with UsenetSearch.  If not, see <https://www.gnu.org/licenses/>.
*/

#include <iostream>

#include "usenetsearch/StringUtils.h"

#include "usenetsearch/Indexer.h"

namespace usenetsearch {

// SearchResult class ----------------------------------------------------------

SearchResult::SearchResult(const ArticleEntry& entry)
{
    m_newsgroupId = entry.newsgroupID;
    m_articleId = entry.articleID;
}

SearchResult::SearchResult(std::uint32_t newsgroupId, std::uint32_t articleId):
    m_newsgroupId(newsgroupId), m_articleId(articleId)
{

}

SearchResult::SearchResult(const SearchResult& other)
{
    m_articleId = other.m_articleId;
    m_newsgroupId = other.m_newsgroupId;
    m_numHits = other.m_numHits;
};

std::uint32_t SearchResult::ArticleId() const
{
    return m_articleId;
}

size_t SearchResult::Hits() const
{
    return m_numHits;
}

void SearchResult::Inc()
{
    m_numHits++;
}

std::uint32_t SearchResult::NewsgroupId() const
{
    return m_newsgroupId;
}

void SearchResult::operator=(const SearchResult& other)
{
    m_articleId = other.m_articleId;
    m_newsgroupId = other.m_newsgroupId;
    m_numHits = other.m_numHits;
}

bool SearchResult::operator==(const SearchResult& other) const
{
    const bool result =
        (m_articleId == other.m_articleId)
        && (m_newsgroupId == other.m_newsgroupId);
    return result;
}

bool SearchResult::operator!=(const SearchResult& other) const
{
    return (
        (m_articleId != other.m_articleId)
        || (m_newsgroupId != other.m_newsgroupId)
    );
}

bool SearchResult::operator<(const SearchResult& other) const
{
    return m_numHits < other.m_numHits;
}

bool SearchResult::operator>(const SearchResult& other) const
{
    return m_numHits > other.m_numHits;
}

bool SearchResult::operator>=(const SearchResult& other) const
{
    return m_numHits >= other.m_numHits;
}

bool SearchResult::operator<=(const SearchResult& other) const
{
    return m_numHits <= other.m_numHits;
}

// Indexer class ---------------------------------------------------------------

Indexer::Indexer(Application& app, UsenetClient& client)
    : m_app(app), m_client(client)
{
    m_threads.MaxThreads(m_app.GetConfig().MaxThreads());
}

void Indexer::Connect()
{
    m_client.Connect(
        m_app.GetConfig().NNTPServerHost(),
        m_app.GetConfig().NNTPServerPort(),
        m_app.GetConfig().NNTPServerSSL()
    );
    m_client.Authenticate(
        m_conv.from_bytes(m_app.GetConfig().NNTPServerUser()),
        m_conv.from_bytes(m_app.GetConfig().NNTPServerPassword())
    );
}

void Indexer::Index(const std::vector<NntpListEntry>& newsgroups)
{
    /**
     * @todo Replace all stdout stuff with Logger class.
     */
    const size_t batchSize = m_app.GetConfig().BatchSize();
    for (const auto& group: newsgroups)
    {
        const std::wstring newsgroup = m_conv.from_bytes(group.name);
        std::cout << "Setting group to " << group.name << "...";
        std::cout.flush();
        m_client.Group(newsgroup);
        std::cout << "DONE." << std::endl;
        std::cout << "Reading headers in " << group.name << " "
                    << "(.=" << batchSize << " headers)." << std::endl;
        std::cout.flush();
        std::atomic<std::uint64_t> headerCount{0};
        const std::atomic<std::uint64_t> groupID = group.id;
        std::reference_wrapper<Database> dbref = std::ref(m_app.GetDb());
        const std::uint32_t startMessage = dbref.get().GetLastIndexedArticle(
            groupID
        );
        std::cout << "Indexing starting at message: " 
                  << std::to_string(startMessage) << std::endl;
        m_client.ProcessHeaders(startMessage,
            [this, &headerCount, &dbref, &groupID](std::shared_ptr<NntpHeaders> headers){
                m_threads.Queue([this, headers, &headerCount, &dbref, &groupID](){
                    std::uint64_t lastArticle{0};
                    for (const auto& header: *headers)
                    {
                        const std::uint64_t articleID{header.articleID};
                        std::string subject = header.subject;
                        subject = m_app.GetFilter().ProcessSearchString(
                            subject
                        );
                        if (subject == "") continue;
                        dbref.get().SaveSearchTokens(
                            groupID,
                            articleID,
                            subject
                        );
                        headerCount++;
                        if (articleID > lastArticle) lastArticle = articleID;
                    }
                    // Update last-indexed id for the newsgroup.
                    const std::uint32_t lastIndexedID =
                        dbref.get().GetLastIndexedArticle(groupID);
                    if (lastIndexedID < lastArticle)
                    {
                        dbref.get().SetLastIndexedArticle(
                            groupID, lastArticle
                        );
                    }
                    std::cout << ".";
                    std::cout.flush();
                });
            },
            batchSize
        );
        m_threads.JoinThreads();
        std::cout << "DONE." << std::endl;
        std::cout << "Saved " << headerCount << " headers." << std::endl;
        std::cout.flush();
    }
}

std::unique_ptr<SearchResults> Indexer::Search(
    const std::string& searchString)
{
    auto result = std::make_unique<SearchResults>();
    const std::string sstr = m_app.GetFilter().ProcessSearchString(
        searchString
    );
    auto searchResults = m_app.GetDb().Search(sstr);
    if (!searchResults) return result;
    for(const ArticleEntry& entry: *searchResults)
    {
        SearchResult sr(entry);
        // Check if a matching entry already exists in the result set, if so,
        // increment count. Otherwise, append a new entry.
        auto it = std::find(result->begin(), result->end(), sr);
        if (it != result->end())
        {
            (*it).Inc();
        }
        else
        {
            sr.Inc();
            result->emplace_back(sr);
        }
    }
    std::sort(
        result->begin(),
        result->end(),
        [](const SearchResult& a, const SearchResult& b){
            return a.Hits() > b.Hits();
        }
    );
    return result;
}

} // namespace usenetsearch