/*
    SPDX-FileCopyrightText: 2015 Klarälvdalens Datakonsult AB a KDAB Group company info@kdab.com
    SPDX-FileContributor: Sérgio Martins <sergio.martins@kdab.com>

    SPDX-FileCopyrightText: 2015 Sergio Martins <smartins@kde.org>

    SPDX-License-Identifier: LGPL-2.0-or-later
*/

#include "checkmanager.h"
#include "Checks.h"
#include "ClazyContext.h"
#include "clazy_stl.h"

#include <llvm/Support/raw_ostream.h>

#include <algorithm>
#include <cassert>
#include <cstdlib>
#include <cstring>
#include <iterator>

using namespace clang;

static const char *s_fixitNamePrefix = "fix-";
static const char *s_levelPrefix = "level";

std::mutex CheckManager::m_lock;

CheckManager::CheckManager()
{
    m_registeredChecks.reserve(100);
    registerChecks();
}

bool CheckManager::checkExists(const std::string &name) const
{
    return checkForName(m_registeredChecks, name) != m_registeredChecks.cend();
}

CheckManager *CheckManager::instance()
{
    static CheckManager s_instance;
    return &s_instance;
}

void CheckManager::registerCheck(const RegisteredCheck &check)
{
    m_registeredChecks.push_back(check);
}

void CheckManager::registerFixIt(int id, const std::string &fixitName, const std::string &checkName)
{
    if (!clazy::startsWith(fixitName, s_fixitNamePrefix)) {
        assert(false);
        return;
    }

    auto &fixits = m_fixitsByCheckName[checkName];
    for (const auto &fixit : fixits) {
        if (fixit.name == fixitName) {
            // It can't exist
            assert(false);
            return;
        }
    }
    RegisteredFixIt fixit = {id, fixitName};
    fixits.push_back(fixit);
    m_fixitByName.insert({fixitName, fixit});
}

CheckBase *CheckManager::createCheck(const std::string &name)
{
    for (const auto &rc : m_registeredChecks) {
        if (rc.name == name) {
            return rc.factory();
        }
    }

    llvm::errs() << "Invalid check name " << name << "\n";
    return nullptr;
}

std::string CheckManager::checkNameForFixIt(const std::string &fixitName) const
{
    if (fixitName.empty()) {
        return {};
    }

    for (const auto &registeredCheck : m_registeredChecks) {
        auto it = m_fixitsByCheckName.find(registeredCheck.name);
        if (it != m_fixitsByCheckName.end()) {
            const auto &fixits = (*it).second;
            for (const RegisteredFixIt &fixit : fixits) {
                if (fixit.name == fixitName) {
                    return (*it).first;
                }
            }
        }
    }

    return {};
}

RegisteredCheck::List CheckManager::availableChecks(CheckLevel maxLevel) const
{
    RegisteredCheck::List checks = m_registeredChecks;

    checks.erase(remove_if(checks.begin(),
                           checks.end(),
                           [maxLevel](const RegisteredCheck &r) {
                               return r.level > maxLevel;
                           }),
                 checks.end());

    return checks;
}

RegisteredCheck::List CheckManager::requestedChecksThroughEnv(std::vector<std::string> &userDisabledChecks) const
{
    static RegisteredCheck::List requestedChecksThroughEnv;
    static std::vector<std::string> disabledChecksThroughEnv;
    if (requestedChecksThroughEnv.empty()) {
        const char *checksEnv = getenv("CLAZY_CHECKS");
        if (checksEnv) {
            const std::string checksEnvStr = clazy::unquoteString(checksEnv);
            requestedChecksThroughEnv =
                checksEnvStr == "all_checks" ? availableChecks(CheckLevel2) : checksForCommaSeparatedString(checksEnvStr, /*by-ref=*/disabledChecksThroughEnv);
        }
    }

    std::copy(disabledChecksThroughEnv.begin(), disabledChecksThroughEnv.end(), std::back_inserter(userDisabledChecks));
    return requestedChecksThroughEnv;
}

RegisteredCheck::List::const_iterator CheckManager::checkForName(const RegisteredCheck::List &checks, const std::string &name) const
{
    return clazy::find_if(checks, [name](const RegisteredCheck &r) {
        return r.name == name;
    });
}

RegisteredFixIt::List CheckManager::availableFixIts(const std::string &checkName) const
{
    auto it = m_fixitsByCheckName.find(checkName);
    return it == m_fixitsByCheckName.end() ? RegisteredFixIt::List() : (*it).second;
}

static bool takeArgument(const std::string &arg, std::vector<std::string> &args)
{
    auto it = clazy::find(args, arg);
    if (it != args.end()) {
        args.erase(it, it + 1);
        return true;
    }

    return false;
}

RegisteredCheck::List CheckManager::requestedChecks(std::vector<std::string> &args)
{
    RegisteredCheck::List result;

    // #1 Check if a level was specified
    static const std::vector<std::string> levels = {"level0", "level1", "level2"};
    const int numLevels = levels.size();
    CheckLevel requestedLevel = CheckLevelUndefined;
    for (int i = 0; i < numLevels; ++i) {
        if (takeArgument(levels.at(i), args)) {
            requestedLevel = static_cast<CheckLevel>(i);
            break;
        }
    }

    if (args.size() > 1) { // we only expect a level and a comma separated list of arguments
        return {};
    }

    std::vector<std::string> userDisabledChecks;
    if (args.size() == 1) {
        // #2 Process list of comma separated checks that were passed to compiler
        result = checksForCommaSeparatedString(args[0], /*by-ref*/ userDisabledChecks);
        if (result.empty() && userDisabledChecks.empty()) { // User passed inexisting checks.
            return {};
        }
    }

    // #3 Append checks specified from env variable
    RegisteredCheck::List checksFromEnv = requestedChecksThroughEnv(/*by-ref*/ userDisabledChecks);
    copy(checksFromEnv.cbegin(), checksFromEnv.cend(), back_inserter(result));

    if (result.empty() && requestedLevel == CheckLevelUndefined) {
        // No checks or level specified, lets use the default level
        requestedLevel = DefaultCheckLevel;
    }

    // #4 Add checks from requested level
    RegisteredCheck::List checksFromRequestedLevel = checksForLevel(requestedLevel);
    clazy::append(checksFromRequestedLevel, result);
    clazy::sort_and_remove_dups(result, checkLessThan);
    CheckManager::removeChecksFromList(result, userDisabledChecks);

    return result;
}

RegisteredCheck::List CheckManager::checksForLevel(int level) const
{
    RegisteredCheck::List result;
    if (level > CheckLevelUndefined && level <= MaxCheckLevel) {
        clazy::append_if(m_registeredChecks, result, [level](const RegisteredCheck &r) {
            return r.level <= level;
        });
    }

    return result;
}

std::vector<std::pair<CheckBase *, RegisteredCheck>> CheckManager::createChecks(const RegisteredCheck::List &requestedChecks, ClazyContext *context)
{
    assert(context);

    std::vector<std::pair<CheckBase *, RegisteredCheck>> checks;
    checks.reserve(requestedChecks.size() + 1);
    for (const auto &check : requestedChecks) {
        checks.emplace_back(createCheck(check.name), check);
    }

    return checks;
}

/*static */
void CheckManager::removeChecksFromList(RegisteredCheck::List &list, std::vector<std::string> &checkNames)
{
    for (auto &name : checkNames) {
        list.erase(remove_if(list.begin(),
                             list.end(),
                             [name](const RegisteredCheck &c) {
                                 return c.name == name;
                             }),
                   list.end());
    }
}

RegisteredCheck::List CheckManager::checksForCommaSeparatedString(const std::string &str) const
{
    std::vector<std::string> byRefDummy;
    return checksForCommaSeparatedString(str, byRefDummy);
}

RegisteredCheck::List CheckManager::checksForCommaSeparatedString(const std::string &str, std::vector<std::string> &userDisabledChecks) const
{
    std::vector<std::string> checkNames = clazy::splitString(str, ',');
    RegisteredCheck::List result;

    for (const std::string &name : checkNames) {
        if (checkForName(result, name) != result.cend()) {
            continue; // Already added. Duplicate check specified. continue.
        }

        auto it = checkForName(m_registeredChecks, name);
        if (it == m_registeredChecks.cend()) {
            // Unknown, but might be a fixit name
            const std::string checkName = checkNameForFixIt(name);
            auto it = checkForName(m_registeredChecks, checkName);
            const bool checkDoesntExist = it == m_registeredChecks.cend();
            if (checkDoesntExist) {
                if (clazy::startsWith(name, s_levelPrefix) && name.size() == strlen(s_levelPrefix) + 1) {
                    auto lastChar = name.back();
                    const int digit = lastChar - '0';
                    if (digit > CheckLevelUndefined && digit <= MaxCheckLevel) {
                        RegisteredCheck::List levelChecks = checksForLevel(digit);
                        clazy::append(levelChecks, result);
                    } else {
                        llvm::errs() << "Invalid level: " << name << "\n";
                    }
                } else {
                    if (clazy::startsWith(name, "no-")) {
                        std::string checkName = name;
                        checkName.erase(0, 3);
                        if (checkExists(checkName)) {
                            userDisabledChecks.push_back(checkName);
                        } else {
                            llvm::errs() << "Invalid check to disable: " << name << "\n";
                        }
                    } else {
                        llvm::errs() << "Invalid check: " << name << "\n";
                    }
                }
            } else {
                result.push_back(*it);
            }
            continue;
        }
        result.push_back(*it);
    }

    removeChecksFromList(result, userDisabledChecks);

    return result;
}

std::vector<std::string> CheckManager::checksAsErrors() const
{
    const auto *checksAsErrosEnv = getenv("CLAZY_CHECKS_AS_ERRORS");

    if (checksAsErrosEnv) {
        auto checkNames = clazy::splitString(checksAsErrosEnv, ',');
        std::vector<std::string> result;

        // Check whether all supplied check names are valid
        for (const std::string &name : checkNames) {
            auto it = clazy::find_if(m_registeredChecks, [&name](const RegisteredCheck &check) {
                return check.name == name;
            });
            if (it == m_registeredChecks.end()) {
                llvm::errs() << "Invalid check: " << name << '\n';
            } else {
                result.emplace_back(name);
            }
        }
        return result;
    }
    return {};
}
