// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

#include <set>
#include <functional>
#include <cassert>

#include <trace.h>
#include <deps_entry.h>
#include <deps_format.h>
#include "deps_resolver.h"
#include <utils.h>
#include <fx_ver.h>

const pal::string_t MissingAssemblyMessage = _X(
    "%s:\n"
    "  An assembly specified in the application dependencies manifest (%s) was not found:\n"
    "    package: '%s', version: '%s'\n"
    "    path: '%s'");

const pal::string_t ManifestListMessage = _X(
    "  This assembly was expected to be in the local runtime store as the application was published using the following target manifest files:\n"
    "    %s");

const pal::string_t DuplicateAssemblyWithDifferentExtensionMessage = _X(
    "Error:\n"
    "  An assembly specified in the application dependencies manifest (%s) has already been found but with a different file extension:\n"
    "    package: '%s', version: '%s'\n"
    "    path: '%s'\n"
    "    previously found assembly: '%s'");

namespace
{
// -----------------------------------------------------------------------------
// A uniqifying append helper that doesn't let two "paths" to be identical in
// the "output" string.
//
void add_unique_path(
    deps_entry_t::asset_types asset_type,
    const pal::string_t& path,
    std::unordered_set<pal::string_t>* existing,
    pal::string_t* serviced,
    pal::string_t* non_serviced,
    const pal::string_t& svc_dir)
{
    // Resolve sym links.
    pal::string_t real = path;
    pal::realpath(&real);

    if (existing->count(real))
    {
        return;
    }

    trace::verbose(_X("Adding to %s path: %s"), deps_entry_t::s_known_asset_types[asset_type], real.c_str());

    if (starts_with(real, svc_dir, false))
    {
        serviced->append(real);
        serviced->push_back(PATH_SEPARATOR);
    }
    else
    {
        non_serviced->append(real);
        non_serviced->push_back(PATH_SEPARATOR);
    }

    existing->insert(real);
}

// Return the filename from deps path; a deps path always uses a '/' for the separator.
pal::string_t get_deps_filename(const pal::string_t& path)
{
    if (path.empty())
    {
        return path;
    }

    auto name_pos = path.find_last_of('/');
    if (name_pos == pal::string_t::npos)
    {
        return path;
    }

    return path.substr(name_pos + 1);
}

} // end of anonymous namespace

  // -----------------------------------------------------------------------------
  // A uniqifying append helper that doesn't let two entries with the same
  // "asset_name" be part of the "items" paths.
  //
void deps_resolver_t::add_tpa_asset(
    const deps_resolved_asset_t& resolved_asset,
    name_to_resolved_asset_map_t* items)
{
    name_to_resolved_asset_map_t::iterator existing = items->find(resolved_asset.asset.name);
    if (existing == items->end())
    {
        trace::verbose(_X("Adding tpa entry: %s, AssemblyVersion: %s, FileVersion: %s"),
            resolved_asset.resolved_path.c_str(),
            resolved_asset.asset.assembly_version.as_str().c_str(),
            resolved_asset.asset.file_version.as_str().c_str());

        items->emplace(resolved_asset.asset.name, resolved_asset);
    }
}

// -----------------------------------------------------------------------------
// Load local assemblies by priority order of their file extensions and
// unique-fied  by their simple name.
//
void deps_resolver_t::get_dir_assemblies(
    const pal::string_t& dir,
    const pal::string_t& dir_name,
    name_to_resolved_asset_map_t* items)
{
    version_t empty;
    trace::verbose(_X("Adding files from %s dir %s"), dir_name.c_str(), dir.c_str());

    // Managed extensions in priority order, pick DLL over EXE and NI over IL.
    const pal::string_t managed_ext[] = { _X(".ni.dll"), _X(".dll"), _X(".ni.exe"), _X(".exe") };

    // List of files in the dir
    std::vector<pal::string_t> files;
    pal::readdir(dir, &files);

    for (const auto& ext : managed_ext)
    {
        for (const auto& file : files)
        {
            // Nothing to do if file length is smaller than expected ext.
            if (file.length() <= ext.length())
            {
                continue;
            }

            auto file_name = file.substr(0, file.length() - ext.length());
            auto file_ext = file.substr(file_name.length());

            // Ext did not match expected ext, skip this file.
            if (pal::strcasecmp(file_ext.c_str(), ext.c_str()))
            {
                continue;
            }

            // Already added entry for this asset, by priority order skip this ext
            if (items->count(file_name))
            {
                trace::verbose(_X("Skipping %s because the %s already exists in %s assemblies"),
                    file.c_str(),
                    items->find(file_name)->second.asset.relative_path.c_str(),
                    dir_name.c_str());

                continue;
            }

            // Add entry for this asset
            pal::string_t file_path = dir;
            if (!file_path.empty() && file_path.back() != DIR_SEPARATOR)
            {
                file_path.push_back(DIR_SEPARATOR);
            }
            file_path.append(file);

            trace::verbose(_X("Adding %s to %s assembly set from %s"),
                file_name.c_str(),
                dir_name.c_str(),
                file_path.c_str());

            deps_asset_t asset(file_name, file, empty, empty);
            deps_resolved_asset_t resolved_asset(asset, file_path);
            add_tpa_asset(resolved_asset, items);
        }
    }
}

void deps_resolver_t::setup_shared_store_probes(
    const arguments_t& args)
{
    for (const auto& shared : args.env_shared_store)
    {
        if (pal::directory_exists(shared))
        {
            // Shared Store probe: DOTNET_SHARED_STORE environment variable
            m_probes.push_back(probe_config_t::lookup(shared));
        }
    }

    if (pal::directory_exists(args.dotnet_shared_store))
    {
        // Path relative to the location of "dotnet.exe" if it's being used to run the app
        m_probes.push_back(probe_config_t::lookup(args.dotnet_shared_store));
    }

    for (const auto& global_shared : args.global_shared_stores)
    {
        if (global_shared != args.dotnet_shared_store && pal::directory_exists(global_shared))
        {
            // Global store probe: the global location
            m_probes.push_back(probe_config_t::lookup(global_shared));
        }
    }
}

pal::string_t deps_resolver_t::get_lookup_probe_directories()
{
    pal::string_t directories;
    for (const auto& pc : m_probes)
    {
        if (pc.is_lookup())
        {
            directories.append(pc.probe_dir);
            directories.push_back(PATH_SEPARATOR);
        }
    }

    return directories;
}

void deps_resolver_t::setup_probe_config(
    const arguments_t& args)
{
    if (pal::directory_exists(args.core_servicing))
    {
        pal::string_t ext_ni = args.core_servicing;
        append_path(&ext_ni, get_arch());
        if (pal::directory_exists(ext_ni))
        {
            // Servicing NI probe.
            m_probes.push_back(probe_config_t::svc_ni(ext_ni));
        }

        // Servicing normal probe.
        pal::string_t ext_pkgs = args.core_servicing;
        append_path(&ext_pkgs, _X("pkgs"));
        m_probes.push_back(probe_config_t::svc(ext_pkgs));
    }

    // The published deps directory to be probed: either app or FX directory.
    // The probe directory will be available at probe time.
    m_probes.push_back(probe_config_t::published_deps_dir());

    // The framework locations, starting with highest level framework.
    for (size_t i = 1; i < m_fx_definitions.size(); ++i)
    {
        if (pal::directory_exists(m_fx_definitions[i]->get_dir()))
        {
            m_probes.push_back(probe_config_t::fx(m_fx_definitions[i]->get_dir(), &m_fx_definitions[i]->get_deps(), i));
        }
    }

    setup_shared_store_probes(args);

    for (const auto& probe : m_additional_probes)
    {
        // Additional paths
        m_probes.push_back(probe_config_t::lookup(probe));
    }

    if (trace::is_enabled())
    {
        trace::verbose(_X("-- Listing probe configurations..."));
        for (const auto& pc : m_probes)
        {
            pc.print();
        }
    }
}

void deps_resolver_t::setup_additional_probes(const std::vector<pal::string_t>& probe_paths)
{
    m_additional_probes.assign(probe_paths.begin(), probe_paths.end());
}

/**
 * Given a deps entry, do a probe (lookup) for the file, based on the probe config.
 *   -- When crossgen-ed folders are looked up, look up only "runtime" (managed) assets.
 *   -- When servicing directories are looked up, look up only if the deps file marks the entry as serviceable.
 *   -- When a deps json based probe is performed, the deps entry's package name and version must match.
 *   -- When looking into a published dir, for rid specific assets lookup rid split folders; for non-rid assets lookup the layout dir.
 */
bool deps_resolver_t::probe_deps_entry(const deps_entry_t& entry, const pal::string_t& deps_dir, int fx_level, pal::string_t* candidate)
{
    candidate->clear();

    for (const auto& config : m_probes)
    {
        trace::verbose(_X("  Considering entry [%s/%s/%s], probe dir [%s], probe fx level:%d, entry fx level:%d"),
            entry.library_name.c_str(), entry.library_version.c_str(), entry.asset.relative_path.c_str(), config.probe_dir.c_str(), config.fx_level, fx_level);

        if (config.only_serviceable_assets && !entry.is_serviceable)
        {
            trace::verbose(_X("    Skipping... not serviceable asset"));
            continue;
        }
        if (config.only_runtime_assets && entry.asset_type != deps_entry_t::asset_types::runtime)
        {
            trace::verbose(_X("    Skipping... not runtime asset"));
            continue;
        }
        pal::string_t probe_dir = config.probe_dir;

        if (config.is_fx())
        {
            assert(config.fx_level > 0);

            // Only probe frameworks that are the same level or lower than the current entry because
            // a lower-level fx should not have a dependency on a higher-level fx and because starting
            // with fx_level allows it to override a higher-level fx location if the entry is newer.
            // Note that fx_level 0 is the highest level (the app)
            if (fx_level <= config.fx_level)
            {
                // If the deps json has the package name and version, then someone has already done rid selection and
                // put the right asset in the dir. So checking just package name and version would suffice.
                // No need to check further for the exact asset relative sub path.
                if (config.probe_deps_json->has_package(entry.library_name, entry.library_version) && entry.to_dir_path(probe_dir, false, candidate))
                {
                    trace::verbose(_X("    Probed deps json and matched '%s'"), candidate->c_str());
                    return true;
                }
            }

            trace::verbose(_X("    Skipping... not found in deps json."));
        }
        else if (config.is_app())
        {
            // This is a published dir probe, so look up rid specific assets in the rid folders.
            assert(config.fx_level == 0);

            if (fx_level <= config.fx_level)
            {
                if (entry.is_rid_specific)
                {
                    if (entry.to_rel_path(deps_dir, true, candidate))
                    {
                        trace::verbose(_X("    Probed deps dir and matched '%s'"), candidate->c_str());
                        return true;
                    }
                }
                else
                {
                    // Non-rid assets, lookup in the published dir.
                    if (entry.to_dir_path(deps_dir, true, candidate))
                    {
                        trace::verbose(_X("    Probed deps dir and matched '%s'"), candidate->c_str());
                        return true;
                    }
                }
            }

            trace::verbose(_X("    Skipping... not found in deps dir '%s'"), deps_dir.c_str());
        }
        else if (entry.to_full_path(probe_dir, candidate))
        {
            trace::verbose(_X("    Probed package dir and matched '%s'"), candidate->c_str());
            return true;
        }

        trace::verbose(_X("    Skipping... not found in probe dir '%s'"), probe_dir.c_str());
        // continue to try next probe config
    }
    return false;
}

bool report_missing_assembly_in_manifest(const deps_entry_t& entry, bool continueResolving = false)
{
    bool showManifestListMessage = !entry.runtime_store_manifest_list.empty();

    if (entry.asset_type == deps_entry_t::asset_types::resources)
    {
        // Treat missing resource assemblies as informational.
        continueResolving = true;

        trace::info(MissingAssemblyMessage.c_str(), _X("Info"),
            entry.deps_file.c_str(), entry.library_name.c_str(), entry.library_version.c_str(), entry.asset.relative_path.c_str());

        if (showManifestListMessage)
        {
            trace::info(ManifestListMessage.c_str(), entry.runtime_store_manifest_list.c_str());
        }
    }
    else if (continueResolving)
    {
        trace::warning(MissingAssemblyMessage.c_str(), _X("Warning"),
            entry.deps_file.c_str(), entry.library_name.c_str(), entry.library_version.c_str(), entry.asset.relative_path.c_str());

        if (showManifestListMessage)
        {
            trace::warning(ManifestListMessage.c_str(), entry.runtime_store_manifest_list.c_str());
        }
    }
    else
    {
        trace::error(MissingAssemblyMessage.c_str(), _X("Error"),
            entry.deps_file.c_str(), entry.library_name.c_str(), entry.library_version.c_str(), entry.asset.relative_path.c_str());

        if (showManifestListMessage)
        {
            trace::error(ManifestListMessage.c_str(), entry.runtime_store_manifest_list.c_str());
        }
    }

    return continueResolving;
}

/**
 *  Resolve the TPA assembly locations
 */
bool deps_resolver_t::resolve_tpa_list(
        pal::string_t* output,
        std::unordered_set<pal::string_t>* breadcrumb,
        bool ignore_missing_assemblies)
{
    name_to_resolved_asset_map_t items;

    auto process_entry = [&](const pal::string_t& deps_dir, const deps_entry_t& entry, int fx_level) -> bool
    {
        if (breadcrumb != nullptr && entry.is_serviceable)
        {
            breadcrumb->insert(entry.library_name + _X(",") + entry.library_version);
            breadcrumb->insert(entry.library_name);
        }

        // Ignore placeholders
        if (ends_with(entry.asset.relative_path, _X("/_._"), false))
        {
            return true;
        }

        trace::info(_X("Processing TPA for deps entry [%s, %s, %s]"), entry.library_name.c_str(), entry.library_version.c_str(), entry.asset.relative_path.c_str());

        pal::string_t resolved_path;

        name_to_resolved_asset_map_t::iterator existing = items.find(entry.asset.name);
        if (existing == items.end())
        {
            if (probe_deps_entry(entry, deps_dir, fx_level, &resolved_path))
            {
                deps_resolved_asset_t resolved_asset(entry.asset, resolved_path);
                add_tpa_asset(resolved_asset, &items);
                return true;
            }

            return report_missing_assembly_in_manifest(entry, ignore_missing_assemblies);
        }
        else
        {
            // Verify the extension is the same as the previous verified entry
            if (get_deps_filename(entry.asset.relative_path) != get_filename(existing->second.resolved_path))
            {
                trace::error(
                    DuplicateAssemblyWithDifferentExtensionMessage.c_str(),
                    entry.deps_file.c_str(),
                    entry.library_name.c_str(),
                    entry.library_version.c_str(),
                    entry.asset.relative_path.c_str(),
                    existing->second.resolved_path.c_str());

                return false;
            }

            deps_resolved_asset_t* existing_entry = &existing->second;

            // If deps entry is same or newer than existing, then see if it should be replaced
            if (entry.asset.assembly_version > existing_entry->asset.assembly_version ||
                (entry.asset.assembly_version == existing_entry->asset.assembly_version && entry.asset.file_version >= existing_entry->asset.file_version))
            {
                if (probe_deps_entry(entry, deps_dir, fx_level, &resolved_path))
                {
                    // If the path is the same, then no need to replace
                    if (resolved_path != existing_entry->resolved_path)
                    {
                        trace::verbose(_X("Replacing deps entry [%s, AssemblyVersion:%s, FileVersion:%s] with [%s, AssemblyVersion:%s, FileVersion:%s]"),
                            existing_entry->resolved_path.c_str(), existing_entry->asset.assembly_version.as_str().c_str(), existing_entry->asset.file_version.as_str().c_str(),
                            resolved_path.c_str(), entry.asset.assembly_version.as_str().c_str(), entry.asset.file_version.as_str().c_str());

                        existing_entry = nullptr;
                        items.erase(existing);

                        deps_asset_t asset(entry.asset.name, entry.asset.relative_path, entry.asset.assembly_version, entry.asset.file_version);
                        deps_resolved_asset_t resolved_asset(asset, resolved_path);
                        add_tpa_asset(resolved_asset, &items);
                    }
                }
                else if (fx_level != 0)
                {
                    // The framework is missing a newer package, so this is an error.
                    // For compat, it is not an error for the app; this can occur for the main application assembly when using --depsfile
                    // and the app assembly does not exist with the deps file.
                    return report_missing_assembly_in_manifest(entry);
                }
            }

            return true;
        }
    };

    // We do not support self-contained in a libhost scenario since in the self-contained scenario,
    // we cannot determine what assemblies are framework assemblies, and what assemblies are app-local assemblies.
    if (m_host_mode != host_mode_t::libhost)
    {
        // First add managed assembly to the TPA.
        // TODO: Remove: the deps should contain the managed DLL.
        // Workaround for: csc.deps.json doesn't have the csc.dll
        deps_asset_t asset(get_filename_without_ext(m_managed_app), get_filename(m_managed_app), version_t(), version_t());
        deps_resolved_asset_t resolved_asset(asset, m_managed_app);
        add_tpa_asset(resolved_asset, &items);

        // Add the app's entries
        const auto& deps_entries = get_deps().get_entries(deps_entry_t::asset_types::runtime);
        for (const auto& entry : deps_entries)
        {
            if (!process_entry(m_app_dir, entry, 0))
            {
                return false;
            }
        }

        // If the deps file wasn't present or has missing entries, then
        // add the app local assemblies to the TPA. This is only valid
        // in non-libhost scenarios (e.g. comhost).
        if (!get_deps().exists())
        {
            // Obtain the local assemblies in the app dir.
            get_dir_assemblies(m_app_dir, _X("local"), &items);
        }
    }

    // There should be no additional deps files in a libhost scenario.
    // See comments during additional deps.json resolution.
    assert(m_additional_deps.empty() || m_host_mode != host_mode_t::libhost);

    // If additional deps files were specified that need to be treated as part of the
    // application, then add them to the mix as well.
    for (const auto& additional_deps : m_additional_deps)
    {
        auto additional_deps_entries = additional_deps->get_entries(deps_entry_t::asset_types::runtime);
        for (auto entry : additional_deps_entries)
        {
            if (!process_entry(m_app_dir, entry, 0))
            {
                return false;
            }
        }
    }

    // Probe FX deps entries after app assemblies are added.
    if (m_is_framework_dependent)
    {
        for (size_t i = 1; i < m_fx_definitions.size(); ++i)
        {
            const auto& deps_entries = m_fx_definitions[i]->get_deps().get_entries(deps_entry_t::asset_types::runtime);
            for (const auto& entry : deps_entries)
            {
                if (!process_entry(m_fx_definitions[i]->get_dir(), entry, i))
                {
                    return false;
                }
            }
        }
    }

    // Convert the paths into a string and return it 
    for (const auto& item : items)
    {
        // Workaround for CoreFX not being able to resolve sym links.
        pal::string_t real_asset_path = item.second.resolved_path;
        pal::realpath(&real_asset_path);
        output->append(real_asset_path);
        output->push_back(PATH_SEPARATOR);
    }

    return true;
}

/**
 * Initialize resolved paths to known entries like coreclr, jit.
 */
void deps_resolver_t::init_known_entry_path(const deps_entry_t& entry, const pal::string_t& path)
{
    if (entry.asset_type != deps_entry_t::asset_types::native)
    {
        return;
    }

    assert(pal::is_path_rooted(path));
    if (m_coreclr_path.empty() && ends_with(path, DIR_SEPARATOR + pal::string_t(LIBCORECLR_NAME), false))
    {
        m_coreclr_path = path;
        m_coreclr_library_version = entry.library_version;
        return;
    }
    if (m_clrjit_path.empty() && ends_with(path, DIR_SEPARATOR + pal::string_t(LIBCLRJIT_NAME), false))
    {
        m_clrjit_path = path;
        return;
    }
}

void deps_resolver_t::resolve_additional_deps(const arguments_t& args, const deps_json_t::rid_fallback_graph_t& rid_fallback_graph)
{
    if (!m_is_framework_dependent
        || m_host_mode == host_mode_t::libhost)
    {
        // Additional deps.json support is only available for framework-dependent apps due to the following constraints:
        //
        // 1) Unlike framework-dependent Apps, self-contained apps do not have details of the SharedFX and Version they target.
        // 2) Unlike framework-dependent Apps, self-contained apps do not have RID fallback graph that is required for looking up
        //    the correct native assets from nuget packages.
        //
        // Additional deps.json support is not available for libhost scenarios. For example, if CoreCLR is instantiated from a
        // library context (i.e. comhost) the activation of classes are assumed to be performed in an AssemblyLoadContext. This
        // assumption is made because it is possible an existing CoreCLR was already activated and it may not satisfy the current
        // needs of the new class.

        return;
    }

    pal::string_t additional_deps_serialized = args.additional_deps_serialized;

    if (additional_deps_serialized.empty())
    {
        return;
    }

    pal::string_t additional_deps_path;
    pal::stringstream_t ss(additional_deps_serialized);

    // Process the delimiter separated custom deps files.
    while (std::getline(ss, additional_deps_path, PATH_SEPARATOR))
    {
        // If it's a single deps file, insert it in 'm_additional_deps_files'
        if (ends_with(additional_deps_path, _X(".deps.json"), false))
        {
            if (pal::file_exists(additional_deps_path))
            {
                trace::verbose(_X("Using specified additional deps.json: '%s'"), 
                    additional_deps_path.c_str());

                m_additional_deps_files.push_back(additional_deps_path);
            }
            else
            {
                trace::warning(_X("Warning: Specified additional deps.json does not exist: '%s'"), 
                    additional_deps_path.c_str());
            }
        }
        else
        {
            for (size_t i = 1; i < m_fx_definitions.size(); ++i)
            {
                fx_ver_t most_compatible_deps_folder_version;
                fx_ver_t framework_found_version;
                fx_ver_t::parse(m_fx_definitions[i]->get_found_version(), &framework_found_version);

                // We'll search deps directories in 'base_dir'/shared/fx_name/ for closest compatible patch version
                pal::string_t additional_deps_path_fx = additional_deps_path;
                append_path(&additional_deps_path_fx, _X("shared"));
                append_path(&additional_deps_path_fx, m_fx_definitions[i]->get_name().c_str());
                trace::verbose(_X("Searching for most compatible deps directory in [%s]"), additional_deps_path_fx.c_str());
                std::vector<pal::string_t> deps_dirs;
                pal::readdir_onlydirectories(additional_deps_path_fx, &deps_dirs);

                for (pal::string_t dir : deps_dirs)
                {
                    fx_ver_t ver;
                    if (fx_ver_t::parse(dir, &ver))
                    {
                        if (ver > most_compatible_deps_folder_version &&
                            ver <= framework_found_version &&
                            ver.get_major() == framework_found_version.get_major() &&
                            ver.get_minor() == framework_found_version.get_minor())
                        {
                            most_compatible_deps_folder_version = ver;
                        }
                    }
                }

                if (most_compatible_deps_folder_version == fx_ver_t())
                {
                    trace::verbose(_X("No additional deps directory less than or equal to [%s] found with same major and minor version."), framework_found_version.as_str().c_str());
                }
                else
                {
                    trace::verbose(_X("Found additional deps directory [%s]"), most_compatible_deps_folder_version.as_str().c_str());

                    append_path(&additional_deps_path_fx, most_compatible_deps_folder_version.as_str().c_str());

                    // The resulting list will be empty if 'additional_deps_path_fx' is not a valid directory path
                    std::vector<pal::string_t> list;
                    pal::readdir(additional_deps_path_fx, _X("*.deps.json"), &list);
                    for (pal::string_t json_file : list)
                    {
                        pal::string_t json_full_path = additional_deps_path_fx;
                        append_path(&json_full_path, json_file.c_str());
                        m_additional_deps_files.push_back(json_full_path);

                        trace::verbose(_X("Using specified additional deps.json: '%s'"),
                            json_full_path.c_str());
                    }
                }
            }
        }
    }

    for (pal::string_t json_file : m_additional_deps_files)
    {
        m_additional_deps.push_back(std::unique_ptr<deps_json_t>(
            new deps_json_t(true, json_file, rid_fallback_graph)));
    }
}

void deps_resolver_t::get_app_fx_definition_range(fx_definition_vector_t::iterator *begin, fx_definition_vector_t::iterator *end) const
{
    assert(begin != nullptr && end != nullptr);

    auto begin_iter = m_fx_definitions.begin();
    auto end_iter = m_fx_definitions.end();

    if (m_host_mode == host_mode_t::libhost
        && begin_iter != end_iter)
    {
        // In a libhost scenario the app definition shouldn't be
        // included in the creation of the application.
        assert(begin_iter->get() == &get_app(m_fx_definitions));
        ++begin_iter;
    }

    *begin = begin_iter;
    *end = end_iter;
}

/**
 *  Resolve native and culture assembly directories based on "asset_type" parameter.
 */
bool deps_resolver_t::resolve_probe_dirs(
        deps_entry_t::asset_types asset_type,
        pal::string_t* output,
        std::unordered_set<pal::string_t>* breadcrumb)
{
    bool is_resources = asset_type == deps_entry_t::asset_types::resources;
    assert(is_resources || asset_type == deps_entry_t::asset_types::native);

    // For resources assemblies, we need to provide the base directory of the resources path.
    // For example: .../Foo/en-US/Bar.dll, then, the resolved path is .../Foo
    std::function<pal::string_t(const pal::string_t&)> resources = [] (const pal::string_t& str) {
        return get_directory(get_directory(str));
    };
    // For native assemblies, obtain the directory path from the file path
    std::function<pal::string_t(const pal::string_t&)> native = [] (const pal::string_t& str) {
        return get_directory(str);
    };
    // Action for post processing the resolved path
    std::function<pal::string_t(const pal::string_t&)>& action = is_resources ? resources : native;

    // Set for de-duplication
    std::unordered_set<pal::string_t> items;

    pal::string_t core_servicing = m_core_servicing;
    pal::realpath(&core_servicing, true);

    // Filter out non-serviced assets so the paths can be added after servicing paths.
    pal::string_t non_serviced;

    pal::string_t candidate;

    auto add_package_cache_entry = [&](const deps_entry_t& entry, const pal::string_t& deps_dir, int fx_level) -> bool
    {
        if (breadcrumb != nullptr && entry.is_serviceable)
        {
            breadcrumb->insert(entry.library_name + _X(",") + entry.library_version);
            breadcrumb->insert(entry.library_name);
        }

        if (items.count(entry.asset.name))
        {
            return true;
        }

        // Ignore placeholders
        if (ends_with(entry.asset.relative_path, _X("/_._"), false))
        {
            return true;
        }

        trace::verbose(_X("Processing native/culture for deps entry [%s, %s, %s]"), 
            entry.library_name.c_str(), entry.library_version.c_str(), entry.asset.relative_path.c_str());

        if (probe_deps_entry(entry, deps_dir, fx_level, &candidate))
        {
            init_known_entry_path(entry, candidate);
            add_unique_path(asset_type, action(candidate), &items, output, &non_serviced, core_servicing);
        }
        else
        {
            // For self-contained apps do not use the full package name
            // because of rid-fallback could happen (ex: CentOS falling back to RHEL)
            if ((entry.asset.name == _X("apphost")) && ends_with(entry.library_name, _X(".Microsoft.NETCore.DotNetAppHost"), false))
            {
                return report_missing_assembly_in_manifest(entry, true);
            }

            return report_missing_assembly_in_manifest(entry);
        }

        return true;
    };

    // Add app entries
    const auto& entries = get_deps().get_entries(asset_type);
    for (const auto& entry : entries)
    {
        if (!add_package_cache_entry(entry, m_app_dir, 0))
        {
            return false;
        }
    }

    // If the deps file is missing add known locations.
    if (!get_deps().exists())
    {
        // App local path
        add_unique_path(asset_type, m_app_dir, &items, output, &non_serviced, core_servicing);

        (void) library_exists_in_dir(m_app_dir, LIBCORECLR_NAME, &m_coreclr_path);
        (void) library_exists_in_dir(m_app_dir, LIBCLRJIT_NAME, &m_clrjit_path);
    }

    // Handle any additional deps.json that were specified.
    for (const auto& additional_deps : m_additional_deps)
    {
        const auto additional_deps_entries = additional_deps->get_entries(asset_type);
        for (const auto& entry : additional_deps_entries)
        {
            if (!add_package_cache_entry(entry, m_app_dir, 0))
            {
                return false;
            }
        }
    }

    // Add fx package locations to fx_dir
    for (size_t i = 1; i < m_fx_definitions.size(); ++i)
    {
        const auto& fx_entries = m_fx_definitions[i]->get_deps().get_entries(asset_type);

        for (const auto& entry : fx_entries)
        {
            if (!add_package_cache_entry(entry, m_fx_definitions[i]->get_dir(), i))
            {
                return false;
            }
        }
    }

    output->append(non_serviced);

    return true;
}


// -----------------------------------------------------------------------------
// Entrypoint to resolve TPA, native and resources path ordering to pass to CoreCLR.
//
//  Parameters:
//     probe_paths       - Pointer to struct containing fields that will contain
//                         resolved path ordering.
//     breadcrumb        - set of breadcrumb paths - or null if no breadcrumbs should be collected.
//     ignore_missing_assemblies - if set to true, resolving TPA assemblies will not fail if an assembly can't be found on disk
//                                 instead such entry will simply be ignored.
//
//
bool deps_resolver_t::resolve_probe_paths(probe_paths_t* probe_paths, std::unordered_set<pal::string_t>* breadcrumb, bool ignore_missing_assemblies)
{
    if (!resolve_tpa_list(&probe_paths->tpa, breadcrumb, ignore_missing_assemblies))
    {
        return false;
    }

    if (!resolve_probe_dirs(deps_entry_t::asset_types::native, &probe_paths->native, breadcrumb))
    {
        return false;
    }

    if (!resolve_probe_dirs(deps_entry_t::asset_types::resources, &probe_paths->resources, breadcrumb))
    {
        return false;
    }

    // If we found coreclr and the jit during native path probe, set the paths now.
    probe_paths->coreclr = m_coreclr_path;
    probe_paths->clrjit = m_clrjit_path;

    return true;
}