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** General Public License version 3 as published by the Free Software
** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
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#include "cppprojectpartchooser.h"

#include <utils/algorithm.h>
#include <utils/qtcassert.h>

namespace CppTools {
namespace Internal {

class ProjectPartPrioritizer
{
public:
    struct PrioritizedProjectPart
    {
        PrioritizedProjectPart(const ProjectPart::Ptr &projectPart, int priority)
            : projectPart(projectPart) , priority(priority) {}

        ProjectPart::Ptr projectPart;
        int priority = 0;
    };

    ProjectPartPrioritizer(const QList<ProjectPart::Ptr> &projectParts,
                           const QString &preferredProjectPartId,
                           const ProjectExplorer::Project *activeProject,
                           Language languagePreference)
        : m_projectParts(projectParts)
        , m_preferredProjectPartId(preferredProjectPartId)
        , m_activeProject(activeProject)
        , m_languagePreference(languagePreference)
    {
        // Determine best project part
        const QList<PrioritizedProjectPart> prioritized = prioritize();
        m_projectPart = prioritized.first().projectPart;

        // Determine ambiguity
        m_isAmbiguous = prioritized.size() > 1
                ? prioritized[0].priority == prioritized[1].priority
                : false;
    }

    ProjectPart::Ptr projectPart()
    {
        return m_projectPart;
    }

    bool isAmbiguous() const
    {
        return m_isAmbiguous;
    }

private:
    QList<PrioritizedProjectPart> prioritize()
    {
        // Prioritize
        QList<PrioritizedProjectPart> prioritized = Utils::transform(m_projectParts,
                [&](const ProjectPart::Ptr &projectPart) {
            return PrioritizedProjectPart{projectPart, priority(*projectPart)};
        });

        // Sort according to priority
        const auto lessThan = [&] (const PrioritizedProjectPart &p1,
                                   const PrioritizedProjectPart &p2) {
            return p1.priority > p2.priority;
        };
        std::stable_sort(prioritized.begin(), prioritized.end(), lessThan);

        return prioritized;
    }

    int priority(const ProjectPart &projectPart) const
    {
        int thePriority = 0;

        if (!m_preferredProjectPartId.isEmpty() && projectPart.id() == m_preferredProjectPartId)
            thePriority += 1000;

        if (projectPart.project == m_activeProject)
            thePriority += 100;

        if (projectPart.selectedForBuilding)
            thePriority += 10;

        if (isPreferredLanguage(projectPart))
            thePriority += 1;

        return thePriority;
    }

    bool isPreferredLanguage(const ProjectPart &projectPart) const
    {
        const bool isCProjectPart = projectPart.languageVersion <= ProjectPart::LatestCVersion;
        return (m_languagePreference == Language::C && isCProjectPart)
            || (m_languagePreference == Language::Cxx && !isCProjectPart);
    }

private:
    const QList<ProjectPart::Ptr> m_projectParts;
    const QString m_preferredProjectPartId;
    const ProjectExplorer::Project *m_activeProject = nullptr;
    Language m_languagePreference = Language::Cxx;

    // Results
    ProjectPart::Ptr m_projectPart;
    bool m_isAmbiguous = false;
};

ProjectPartInfo ProjectPartChooser::choose(const QString &filePath,
        const ProjectPartInfo &currentProjectPartInfo,
        const QString &preferredProjectPartId,
        const ProjectExplorer::Project *activeProject,
        Language languagePreference,
        bool projectHasChanged) const
{
    QTC_CHECK(m_projectPartsForFile);
    QTC_CHECK(m_projectPartsFromDependenciesForFile);
    QTC_CHECK(m_fallbackProjectPart);

    ProjectPart::Ptr projectPart = currentProjectPartInfo.projectPart;
    ProjectPartInfo::Hint hint = ProjectPartInfo::NoHint;

    QList<ProjectPart::Ptr> projectParts = m_projectPartsForFile(filePath);
    if (projectParts.isEmpty()) {
        if (projectPart && currentProjectPartInfo.hint == ProjectPartInfo::IsFallbackMatch)
            // Avoid re-calculating the expensive dependency table for non-project files.
            return {projectPart, ProjectPartInfo::IsFallbackMatch};

        // Fall-back step 1: Get some parts through the dependency table:
        projectParts = m_projectPartsFromDependenciesForFile(filePath);
        if (projectParts.isEmpty()) {
            // Fall-back step 2: Use fall-back part from the model manager:
            projectPart = m_fallbackProjectPart();
            hint = ProjectPartInfo::IsFallbackMatch;
        } else {
            ProjectPartPrioritizer prioritizer(projectParts,
                                               preferredProjectPartId,
                                               activeProject,
                                               languagePreference);
            projectPart = prioritizer.projectPart();
        }
    } else {
        if (projectHasChanged || !projectParts.contains(projectPart)) {
            ProjectPartPrioritizer prioritizer(projectParts,
                                               preferredProjectPartId,
                                               activeProject,
                                               languagePreference);
            projectPart = prioritizer.projectPart();
            hint = prioritizer.isAmbiguous()
                    ? ProjectPartInfo::IsAmbiguousMatch
                    : ProjectPartInfo::NoHint;
        }
    }

    return {projectPart, hint};
}

void ProjectPartChooser::setFallbackProjectPart(const FallBackProjectPart &getter)
{
    m_fallbackProjectPart = getter;
}

void ProjectPartChooser::setProjectPartsForFile(const ProjectPartsForFile &getter)
{
    m_projectPartsForFile = getter;
}

void ProjectPartChooser::setProjectPartsFromDependenciesForFile(
        const ProjectPartsFromDependenciesForFile &getter)
{
    m_projectPartsFromDependenciesForFile = getter;
}

} // namespace Internal
} // namespace CppTools