#include "nix/store/derivations.hh"
#include "nix/store/parsed-derivations.hh"
#include "nix/store/derivation-options.hh"
#include "nix/store/globals.hh"
#include "nix/store/store-open.hh"
#include "nix/util/thread-pool.hh"
#include "nix/store/realisation.hh"
#include "nix/util/topo-sort.hh"
#include "nix/util/callback.hh"
#include "nix/util/closure.hh"
#include "nix/store/filetransfer.hh"
#include "nix/util/strings.hh"

#include <boost/unordered/unordered_flat_set.hpp>

namespace nix {

void Store::computeFSClosure(
    const StorePathSet & startPaths,
    StorePathSet & paths_,
    bool flipDirection,
    bool includeOutputs,
    bool includeDerivers)
{
    std::function<std::set<StorePath>(const StorePath & path, std::future<ref<const ValidPathInfo>> &)> queryDeps;
    if (flipDirection)
        queryDeps = [&](const StorePath & path, std::future<ref<const ValidPathInfo>> & fut) {
            StorePathSet res;
            StorePathSet referrers;
            queryReferrers(path, referrers);
            for (auto & ref : referrers)
                if (ref != path)
                    res.insert(ref);

            if (includeOutputs)
                for (auto & i : queryValidDerivers(path))
                    res.insert(i);

            if (includeDerivers && path.isDerivation())
                for (auto & [_, maybeOutPath] : queryPartialDerivationOutputMap(path))
                    if (maybeOutPath && isValidPath(*maybeOutPath))
                        res.insert(*maybeOutPath);
            return res;
        };
    else
        queryDeps = [&](const StorePath & path, std::future<ref<const ValidPathInfo>> & fut) {
            StorePathSet res;
            auto info = fut.get();
            for (auto & ref : info->references)
                if (ref != path)
                    res.insert(ref);

            if (includeOutputs && path.isDerivation())
                for (auto & [_, maybeOutPath] : queryPartialDerivationOutputMap(path))
                    if (maybeOutPath && isValidPath(*maybeOutPath))
                        res.insert(*maybeOutPath);

            if (includeDerivers && info->deriver && isValidPath(*info->deriver))
                res.insert(*info->deriver);
            return res;
        };

    computeClosure<StorePath>(
        startPaths,
        paths_,
        [&](const StorePath & path, std::function<void(std::promise<std::set<StorePath>> &)> processEdges) {
            std::promise<std::set<StorePath>> promise;
            std::function<void(std::future<ref<const ValidPathInfo>>)> getDependencies =
                [&](std::future<ref<const ValidPathInfo>> fut) {
                    try {
                        promise.set_value(queryDeps(path, fut));
                    } catch (...) {
                        promise.set_exception(std::current_exception());
                    }
                };
            queryPathInfo(path, getDependencies);
            processEdges(promise);
        });
}

void Store::computeFSClosure(
    const StorePath & startPath, StorePathSet & paths_, bool flipDirection, bool includeOutputs, bool includeDerivers)
{
    StorePathSet paths;
    paths.insert(startPath);
    computeFSClosure(paths, paths_, flipDirection, includeOutputs, includeDerivers);
}

const ContentAddress * getDerivationCA(const BasicDerivation & drv)
{
    auto out = drv.outputs.find("out");
    if (out == drv.outputs.end())
        return nullptr;
    if (auto dof = std::get_if<DerivationOutput::CAFixed>(&out->second.raw)) {
        return &dof->ca;
    }
    return nullptr;
}

MissingPaths Store::queryMissing(const std::vector<DerivedPath> & targets)
{
    Activity act(*logger, lvlDebug, actUnknown, "querying info about missing paths");

    // FIXME: make async.
    ThreadPool pool(fileTransferSettings.httpConnections);

    struct State
    {
        boost::unordered_flat_set<std::string> done;
        MissingPaths res;
    };

    struct DrvState
    {
        size_t left;
        bool done = false;
        StorePathSet outPaths;

        DrvState(size_t left)
            : left(left)
        {
        }
    };

    Sync<State> state_;

    std::function<void(DerivedPath)> doPath;

    auto enqueueDerivedPaths = [&](this auto self,
                                   ref<SingleDerivedPath> inputDrv,
                                   const DerivedPathMap<StringSet>::ChildNode & inputNode) -> void {
        if (!inputNode.value.empty())
            pool.enqueue(std::bind(doPath, DerivedPath::Built{inputDrv, inputNode.value}));
        for (const auto & [outputName, childNode] : inputNode.childMap)
            self(make_ref<SingleDerivedPath>(SingleDerivedPath::Built{inputDrv, outputName}), childNode);
    };

    auto mustBuildDrv = [&](const StorePath & drvPath, const Derivation & drv) {
        {
            auto state(state_.lock());
            state->res.willBuild.insert(drvPath);
        }

        for (const auto & [inputDrv, inputNode] : drv.inputDrvs.map) {
            enqueueDerivedPaths(makeConstantStorePathRef(inputDrv), inputNode);
        }
    };

    auto checkOutput =
        [&](const StorePath & drvPath, ref<Derivation> drv, const StorePath & outPath, ref<Sync<DrvState>> drvState_) {
            if (drvState_->lock()->done)
                return;

            SubstitutablePathInfos infos;
            auto * cap = getDerivationCA(*drv);
            querySubstitutablePathInfos(
                {
                    {
                        outPath,
                        cap ? std::optional{*cap} : std::nullopt,
                    },
                },
                infos);

            if (infos.empty()) {
                drvState_->lock()->done = true;
                mustBuildDrv(drvPath, *drv);
            } else {
                {
                    auto drvState(drvState_->lock());
                    if (drvState->done)
                        return;
                    assert(drvState->left);
                    drvState->left--;
                    drvState->outPaths.insert(outPath);
                    if (!drvState->left) {
                        for (auto & path : drvState->outPaths)
                            pool.enqueue(std::bind(doPath, DerivedPath::Opaque{path}));
                    }
                }
            }
        };

    doPath = [&](const DerivedPath & req) {
        {
            auto state(state_.lock());
            if (!state->done.insert(req.to_string(*this)).second)
                return;
        }

        std::visit(
            overloaded{
                [&](const DerivedPath::Built & bfd) {
                    auto drvPathP = std::get_if<DerivedPath::Opaque>(&*bfd.drvPath);
                    if (!drvPathP) {
                        // TODO make work in this case.
                        warn(
                            "Ignoring dynamic derivation %s while querying missing paths; not yet implemented",
                            bfd.drvPath->to_string(*this));
                        return;
                    }
                    auto & drvPath = drvPathP->path;

                    if (!isValidPath(drvPath)) {
                        // FIXME: we could try to substitute the derivation.
                        auto state(state_.lock());
                        state->res.unknown.insert(drvPath);
                        return;
                    }

                    StorePathSet invalid;
                    /* true for regular derivations, and CA derivations for which we
                       have a trust mapping for all wanted outputs. */
                    auto knownOutputPaths = true;
                    for (auto & [outputName, pathOpt] : queryPartialDerivationOutputMap(drvPath)) {
                        if (!pathOpt) {
                            knownOutputPaths = false;
                            break;
                        }
                        if (bfd.outputs.contains(outputName) && !isValidPath(*pathOpt))
                            invalid.insert(*pathOpt);
                    }
                    if (knownOutputPaths && invalid.empty())
                        return;

                    auto drv = make_ref<Derivation>(derivationFromPath(drvPath));
                    DerivationOptions drvOptions;
                    try {
                        // FIXME: this is a lot of work just to get the value
                        // of `allowSubstitutes`.
                        drvOptions = DerivationOptions::fromStructuredAttrs(drv->env, drv->structuredAttrs);
                    } catch (Error & e) {
                        e.addTrace({}, "while parsing derivation '%s'", printStorePath(drvPath));
                        throw;
                    }

                    if (!knownOutputPaths && settings.useSubstitutes && drvOptions.substitutesAllowed()) {
                        experimentalFeatureSettings.require(Xp::CaDerivations);

                        // If there are unknown output paths, attempt to find if the
                        // paths are known to substituters through a realisation.
                        auto outputHashes = staticOutputHashes(*this, *drv);
                        knownOutputPaths = true;

                        for (auto [outputName, hash] : outputHashes) {
                            if (!bfd.outputs.contains(outputName))
                                continue;

                            bool found = false;
                            for (auto & sub : getDefaultSubstituters()) {
                                auto realisation = sub->queryRealisation({hash, outputName});
                                if (!realisation)
                                    continue;
                                found = true;
                                if (!isValidPath(realisation->outPath))
                                    invalid.insert(realisation->outPath);
                                break;
                            }
                            if (!found) {
                                // Some paths did not have a realisation, this must be built.
                                knownOutputPaths = false;
                                break;
                            }
                        }
                    }

                    if (knownOutputPaths && settings.useSubstitutes && drvOptions.substitutesAllowed()) {
                        auto drvState = make_ref<Sync<DrvState>>(DrvState(invalid.size()));
                        for (auto & output : invalid)
                            pool.enqueue(std::bind(checkOutput, drvPath, drv, output, drvState));
                    } else
                        mustBuildDrv(drvPath, *drv);
                },
                [&](const DerivedPath::Opaque & bo) {
                    if (isValidPath(bo.path))
                        return;

                    SubstitutablePathInfos infos;
                    querySubstitutablePathInfos({{bo.path, std::nullopt}}, infos);

                    if (infos.empty()) {
                        auto state(state_.lock());
                        state->res.unknown.insert(bo.path);
                        return;
                    }

                    auto info = infos.find(bo.path);
                    assert(info != infos.end());

                    {
                        auto state(state_.lock());
                        state->res.willSubstitute.insert(bo.path);
                        state->res.downloadSize += info->second.downloadSize;
                        state->res.narSize += info->second.narSize;
                    }

                    for (auto & ref : info->second.references)
                        pool.enqueue(std::bind(doPath, DerivedPath::Opaque{ref}));
                },
            },
            req.raw());
    };

    for (auto & path : targets)
        pool.enqueue(std::bind(doPath, path));

    pool.process();

    return std::move(state_.lock()->res);
}

StorePaths Store::topoSortPaths(const StorePathSet & paths)
{
    return topoSort(
        paths,
        {[&](const StorePath & path) {
            try {
                return queryPathInfo(path)->references;
            } catch (InvalidPath &) {
                return StorePathSet();
            }
        }},
        {[&](const StorePath & path, const StorePath & parent) {
            return BuildError(
                BuildResult::Failure::OutputRejected,
                "cycle detected in the references of '%s' from '%s'",
                printStorePath(path),
                printStorePath(parent));
        }});
}

OutputPathMap resolveDerivedPath(Store & store, const DerivedPath::Built & bfd, Store * evalStore_)
{
    auto drvPath = resolveDerivedPath(store, *bfd.drvPath, evalStore_);

    auto outputsOpt_ = store.queryPartialDerivationOutputMap(drvPath, evalStore_);

    auto outputsOpt = std::visit(
        overloaded{
            [&](const OutputsSpec::All &) {
                // Keep all outputs
                return std::move(outputsOpt_);
            },
            [&](const OutputsSpec::Names & names) {
                // Get just those mentioned by name
                std::map<std::string, std::optional<StorePath>> outputsOpt;
                for (auto & output : names) {
                    auto * pOutputPathOpt = get(outputsOpt_, output);
                    if (!pOutputPathOpt)
                        throw Error(
                            "the derivation '%s' doesn't have an output named '%s'",
                            bfd.drvPath->to_string(store),
                            output);
                    outputsOpt.insert_or_assign(output, std::move(*pOutputPathOpt));
                }
                return outputsOpt;
            },
        },
        bfd.outputs.raw);

    OutputPathMap outputs;
    for (auto & [outputName, outputPathOpt] : outputsOpt) {
        if (!outputPathOpt)
            throw MissingRealisation(bfd.drvPath->to_string(store), outputName);
        auto & outputPath = *outputPathOpt;
        outputs.insert_or_assign(outputName, outputPath);
    }
    return outputs;
}

StorePath resolveDerivedPath(Store & store, const SingleDerivedPath & req, Store * evalStore_)
{
    auto & evalStore = evalStore_ ? *evalStore_ : store;

    return std::visit(
        overloaded{
            [&](const SingleDerivedPath::Opaque & bo) { return bo.path; },
            [&](const SingleDerivedPath::Built & bfd) {
                auto drvPath = resolveDerivedPath(store, *bfd.drvPath, evalStore_);
                auto outputPaths = evalStore.queryPartialDerivationOutputMap(drvPath, evalStore_);
                if (outputPaths.count(bfd.output) == 0)
                    throw Error(
                        "derivation '%s' does not have an output named '%s'",
                        store.printStorePath(drvPath),
                        bfd.output);
                auto & optPath = outputPaths.at(bfd.output);
                if (!optPath)
                    throw MissingRealisation(bfd.drvPath->to_string(store), bfd.output);
                return *optPath;
            },
        },
        req.raw());
}

OutputPathMap resolveDerivedPath(Store & store, const DerivedPath::Built & bfd)
{
    auto drvPath = resolveDerivedPath(store, *bfd.drvPath);
    auto outputMap = store.queryDerivationOutputMap(drvPath);
    auto outputsLeft = std::visit(
        overloaded{
            [&](const OutputsSpec::All &) { return StringSet{}; },
            [&](const OutputsSpec::Names & names) { return static_cast<StringSet>(names); },
        },
        bfd.outputs.raw);
    for (auto iter = outputMap.begin(); iter != outputMap.end();) {
        auto & outputName = iter->first;
        if (bfd.outputs.contains(outputName)) {
            outputsLeft.erase(outputName);
            ++iter;
        } else {
            iter = outputMap.erase(iter);
        }
    }
    if (!outputsLeft.empty())
        throw Error(
            "derivation '%s' does not have an outputs %s",
            store.printStorePath(drvPath),
            concatStringsSep(", ", quoteStrings(std::get<OutputsSpec::Names>(bfd.outputs.raw))));
    return outputMap;
}

} // namespace nix