#include "fetch.h"

#include <yql/essentials/utils/log/log.h>

#include <library/cpp/openssl/io/stream.h>
#include <library/cpp/http/misc/httpcodes.h>
#include <library/cpp/charset/ci_string.h>

#include <util/network/socket.h>
#include <util/string/cast.h>
#include <util/generic/strbuf.h>

namespace NYql {

namespace {

THttpURL ParseURL(const TStringBuf addr, NUri::TParseFlags features) {
    THttpURL url;
    THttpURL::TParsedState parsedState = url.Parse(addr, features, nullptr, 65536);
    if (THttpURL::ParsedOK != parsedState) {
        ythrow yexception() << "Bad URL: \"" << addr << "\", " << HttpURLParsedStateToString(parsedState);
    }
    return url;
}

class TFetchResultImpl: public IFetchResult {
public:
    TFetchResultImpl(const THttpURL& url, const THttpHeaders& additionalHeaders, TDuration timeout) {
        TString host = url.Get(THttpURL::FieldHost);
        TString path = url.PrintS(THttpURL::FlagPath | THttpURL::FlagQuery);
        const char* p = url.Get(THttpURL::FieldPort);
        ui16 port = 80;
        bool https = false;

        if (url.Get(THttpURL::FieldScheme) == TStringBuf("https")) {
            port = 443;
            https = true;
        }

        if (p) {
            port = FromString<ui16>(p);
        }

        TString req;
        {
            TStringOutput rqs(req);
            TStringBuf userAgent = "User-Agent: Mozilla/5.0 (compatible; YQL/1.0)";

            IOutputStream::TPart request[] = {
                IOutputStream::TPart("GET ", 4),
                IOutputStream::TPart(path.data(), path.size()),
                IOutputStream::TPart(" HTTP/1.1", 9),
                IOutputStream::TPart::CrLf(),
                IOutputStream::TPart("Host: ", 6),
                IOutputStream::TPart(host.data(), host.size()),
                IOutputStream::TPart::CrLf(),
                IOutputStream::TPart(userAgent.data(), userAgent.size()),
                IOutputStream::TPart::CrLf(),
            };
            rqs.Write(request, Y_ARRAY_SIZE(request));
            if (!additionalHeaders.Empty()) {
                additionalHeaders.OutTo(&rqs);
            }
            rqs << "\r\n";
        }

        Socket.Reset(new TSocket(TNetworkAddress(host, port), timeout));
        SocketInput.Reset(new TSocketInput(*Socket));
        SocketOutput.Reset(new TSocketOutput(*Socket));

        Socket->SetSocketTimeout(timeout.Seconds(), timeout.MilliSeconds() % 1000);

        if (https) {
            Ssl.Reset(new TOpenSslClientIO(SocketInput.Get(), SocketOutput.Get()));
        }

        {
            THttpOutput ho(Ssl ? (IOutputStream*)Ssl.Get() : (IOutputStream*)SocketOutput.Get());
            (ho << req).Finish();
        }
        HttpInput.Reset(new THttpInput(Ssl ? (IInputStream*)Ssl.Get() : (IInputStream*)SocketInput.Get()));
    }

    THttpInput& GetStream() override {
        return *HttpInput;
    }

    unsigned GetRetCode() override {
        return ParseHttpRetCode(HttpInput->FirstLine());
    }

    THttpURL GetRedirectURL(const THttpURL& baseUrl) override {
        for (auto i = HttpInput->Headers().Begin(); i != HttpInput->Headers().End(); ++i) {
            if (0 == TCiString::compare(i->Name(), TStringBuf("location"))) {
                THttpURL target = ParseURL(i->Value(), THttpURL::FeaturesAll | NUri::TFeature::FeatureConvertHostIDN);
                if (!target.IsValidAbs()) {
                    target.Merge(baseUrl);
                }
                return target;
            }
        }
        ythrow yexception() << "Unknown redirect location from " << baseUrl.PrintS();
    }

    static TFetchResultPtr Fetch(const THttpURL& url, const THttpHeaders& additionalHeaders, const TDuration& timeout) {
        return new TFetchResultImpl(url, additionalHeaders, timeout);
    }

private:
    THolder<TSocket> Socket;
    THolder<TSocketInput> SocketInput;
    THolder<TSocketOutput> SocketOutput;
    THolder<TOpenSslClientIO> Ssl;
    THolder<THttpInput> HttpInput;
};

inline bool IsRedirectCode(unsigned code) {
    switch (code) {
        case HTTP_MOVED_PERMANENTLY:
        case HTTP_FOUND:
        case HTTP_SEE_OTHER:
        case HTTP_TEMPORARY_REDIRECT:
            return true;
    }
    return false;
}

inline bool IsRetryCode(unsigned code) {
    switch (code) {
        case HTTP_REQUEST_TIME_OUT:
        case HTTP_AUTHENTICATION_TIMEOUT:
        case HTTP_TOO_MANY_REQUESTS:
        case HTTP_GATEWAY_TIME_OUT:
        case HTTP_SERVICE_UNAVAILABLE:
            return true;
    }
    return false;
}

} // unnamed

THttpURL ParseURL(const TStringBuf addr) {
    return ParseURL(addr, THttpURL::FeaturesAll | NUri::TFeature::FeatureConvertHostIDN | NUri::TFeature::FeatureNoRelPath);
}

TFetchResultPtr Fetch(const THttpURL& url, const THttpHeaders& additionalHeaders, const TDuration& timeout, size_t retries, size_t redirects) {
    THttpURL currentUrl = url;
    for (size_t fetchNum = 0; fetchNum < redirects; ++fetchNum) {
        unsigned responseCode = 0;
        TFetchResultPtr fr;
        size_t fetchTry = 0;
        do {
            fr = TFetchResultImpl::Fetch(currentUrl, additionalHeaders, timeout);
            responseCode = fr->GetRetCode();
        } while (IsRetryCode(responseCode) && ++fetchTry < retries);

        if (responseCode >= 200 && responseCode < 300) {
            return fr;
        }

        if (responseCode == HTTP_NOT_MODIFIED) {
            return fr;
        }

        if (IsRedirectCode(responseCode)) {
            currentUrl = fr->GetRedirectURL(currentUrl);
            YQL_LOG(INFO) << "Got redirect to " << currentUrl.PrintS();
            continue;
        }

        TString errorBody;
        try {
            errorBody = fr->GetStream().ReadAll();
        } catch (...) {
        }

        ythrow yexception() << "Failed to fetch url '" << currentUrl.PrintS() << "' with code " << responseCode << ", body: " << errorBody;
    }
    ythrow yexception() << "Failed to fetch url '" << currentUrl.PrintS() << "': too many redirects";
}

} // NYql