/*
 * SPDX-FileCopyrightText: 2016-2016 CSSlayer <wengxt@gmail.com>
 *
 * SPDX-License-Identifier: LGPL-2.1-or-later
 *
 */

#include "userinterfacemanager.h"
#include <set>
#include "fcitx/event.h"
#include "action.h"
#include "inputcontext.h"
#include "instance.h"
#include "userinterface.h"

namespace fcitx {

struct UserInterfaceComponentHash {
    template <typename T>
    std::underlying_type_t<T> operator()(T t) const {
        return static_cast<std::underlying_type_t<T>>(t);
    }
};

class IdAllocator {
public:
    int allocId() {
        if (freeList_.empty()) {
            ++maxId_;
            return maxId_;
        }
        auto value = *freeList_.begin();
        freeList_.erase(freeList_.begin());
        return value;
    }
    void returnId(int id) {
        assert(id <= maxId_ && freeList_.count(id) == 0);
        freeList_.insert(id);
    }

    std::set<int> freeList_;
    int maxId_ = 0;
};

class UserInterfaceManagerPrivate {
public:
    UserInterfaceManagerPrivate(AddonManager *addonManager)
        : addonManager_(addonManager) {}

    void registerAction(const std::string &name, int id, Action *action) {
        ScopedConnection conn = action->connect<ObjectDestroyed>(
            [this, action](void *) { unregisterAction(action); });
        action->setName(name);
        action->setId(id);
        actions_.emplace(name, std::make_pair(action, std::move(conn)));
        idToAction_.emplace(action->id(), action);
    }

    void unregisterAction(Action *action) {
        auto iter = actions_.find(action->name());
        if (iter == actions_.end()) {
            return;
        }
        if (std::get<0>(iter->second) != action) {
            return;
        }
        actions_.erase(iter);
        idToAction_.erase(action->id());
        ids_.returnId(action->id());
        action->setName(std::string());
        action->setId(0);
    }

    void updateDispatch(UserInterfaceComponent comp, InputContext *ic);

    template <UserInterfaceComponent component>
    void updateSingleComponent(InputContext *ic);

    UserInterface *ui_ = nullptr;
    std::string uiName_;
    std::vector<std::string> uis_;

    std::unordered_map<std::string, std::pair<Action *, ScopedConnection>>
        actions_;
    std::unordered_map<int, Action *> idToAction_;

    typedef std::list<std::pair<
        InputContext *, std::unordered_set<UserInterfaceComponent, EnumHash>>>
        UIUpdateList;
    UIUpdateList updateList_;
    std::unordered_map<InputContext *, UIUpdateList::iterator> updateIndex_;
    AddonManager *addonManager_;

    IdAllocator ids_;
    bool isVirtualKeyboardVisible_ = false;
};

template <>
void UserInterfaceManagerPrivate::updateSingleComponent<
    UserInterfaceComponent::InputPanel>(InputContext *ic) {
    if (const auto &virtualKeyboardCallback =
            ic->inputPanel().customVirtualKeyboardCallback()) {
        virtualKeyboardCallback(ic);
    } else if (ui_ != nullptr && ui_->addonInfo() != nullptr &&
               ui_->addonInfo()->uiType() == UIType::OnScreenKeyboard) {
        ui_->update(UserInterfaceComponent::InputPanel, ic);
    } else if (const auto &callback =
                   ic->inputPanel().customInputPanelCallback()) {
        callback(ic);
    } else if (ic->capabilityFlags().test(
                   CapabilityFlag::ClientSideInputPanel)) {
        ic->updateClientSideUIImpl();
    } else if (ui_) {
        ui_->update(UserInterfaceComponent::InputPanel, ic);
    }
}

template <>
void UserInterfaceManagerPrivate::updateSingleComponent<
    UserInterfaceComponent::StatusArea>(InputContext *ic) {
    if (ui_) {
        ui_->update(UserInterfaceComponent::StatusArea, ic);
    }
}

void UserInterfaceManagerPrivate::updateDispatch(UserInterfaceComponent comp,
                                                 InputContext *ic) {
#define _UI_CASE(COMP)                                                         \
    case COMP:                                                                 \
        updateSingleComponent<COMP>(ic);                                       \
        break

    switch (comp) {
        _UI_CASE(UserInterfaceComponent::InputPanel);
        _UI_CASE(UserInterfaceComponent::StatusArea);
    }
#undef _UI_CASE
}

UserInterfaceManager::UserInterfaceManager(AddonManager *addonManager)
    : d_ptr(std::make_unique<UserInterfaceManagerPrivate>(addonManager)) {}

UserInterfaceManager::~UserInterfaceManager() {}

void UserInterfaceManager::load(const std::string &uiName) {
    FCITX_D();
    auto names = d->addonManager_->addonNames(AddonCategory::UI);

    d->uis_.clear();
    if (names.count(uiName)) {
        auto *ui = d->addonManager_->addon(uiName, true);
        if (ui) {
            d->uis_.push_back(uiName);
        }
    }

    if (d->uis_.empty()) {
        d->uis_.insert(d->uis_.end(), names.begin(), names.end());
        std::sort(d->uis_.begin(), d->uis_.end(),
                  [d](const std::string &lhs, const std::string &rhs) {
                      auto linfo = d->addonManager_->addonInfo(lhs);
                      auto rinfo = d->addonManager_->addonInfo(rhs);
                      if (!linfo) {
                          return false;
                      }
                      if (!rinfo) {
                          return true;
                      }
                      auto lp = linfo->uiPriority();
                      auto rp = rinfo->uiPriority();
                      if (lp == rp) {
                          return lhs > rhs;
                      }
                      return lp > rp;
                  });
    }
    updateAvailability();
}

bool UserInterfaceManager::registerAction(Action *action) {
    FCITX_D();
    auto id = d->ids_.allocId();
    auto name = stringutils::concat("$", id);
    auto iter = d->actions_.find(name);
    // This should never happen.
    if (iter != d->actions_.end()) {
        FCITX_ERROR() << "Reserved id is used, how can this be possible?";
        d->ids_.returnId(id);
        return false;
    }
    d->registerAction(name, id, action);
    return true;
}

bool UserInterfaceManager::registerAction(const std::string &name,
                                          Action *action) {
    FCITX_D();
    if (!action->name().empty() || name.empty()) {
        return false;
    }
    if (stringutils::startsWith(name, "$")) {
        FCITX_ERROR() << "Action name starts with $ is reserved.";
        return false;
    }
    auto iter = d->actions_.find(name);
    if (iter != d->actions_.end()) {
        return false;
    }

    d->registerAction(name, d->ids_.allocId(), action);
    return true;
}

void UserInterfaceManager::unregisterAction(Action *action) {
    FCITX_D();
    d->unregisterAction(action);
}

Action *UserInterfaceManager::lookupAction(const std::string &name) const {
    FCITX_D();
    auto iter = d->actions_.find(name);
    if (iter == d->actions_.end()) {
        return nullptr;
    }
    return std::get<0>(iter->second);
}

Action *UserInterfaceManager::lookupActionById(int id) const {
    FCITX_D();
    auto iter = d->idToAction_.find(id);
    if (iter == d->idToAction_.end()) {
        return nullptr;
    }
    return iter->second;
}

void UserInterfaceManager::update(UserInterfaceComponent component,
                                  InputContext *inputContext) {
    FCITX_D();
    auto iter = d->updateIndex_.find(inputContext);
    decltype(d->updateList_)::iterator listIter;
    if (d->updateIndex_.end() == iter) {
        d->updateList_.emplace_back(std::piecewise_construct,
                                    std::forward_as_tuple(inputContext),
                                    std::forward_as_tuple());
        d->updateIndex_[inputContext] = listIter =
            std::prev(d->updateList_.end());
    } else {
        listIter = iter->second;
    }
    listIter->second.insert(component);
}

void UserInterfaceManager::expire(InputContext *inputContext) {
    FCITX_D();
    auto iter = d->updateIndex_.find(inputContext);
    if (d->updateIndex_.end() != iter) {
        d->updateList_.erase(iter->second);
        d->updateIndex_.erase(iter);
    }
}

void UserInterfaceManager::flush() {
    FCITX_D();
    auto *instance = d->addonManager_->instance();
    for (auto &p : d->updateList_) {
        for (auto comp : p.second) {
            instance->postEvent(InputContextFlushUIEvent(comp, p.first));
            d->updateDispatch(comp, p.first);
        }
    }
    d->updateIndex_.clear();
    d->updateList_.clear();
}

bool isUserInterfaceValid(UserInterface *userInterface,
                          InputMethodMode inputMethodMode) {
    if (userInterface == nullptr || !userInterface->available() ||
        userInterface->addonInfo() == nullptr) {
        return false;
    }

    return (userInterface->addonInfo()->uiType() == UIType::OnScreenKeyboard &&
            inputMethodMode == InputMethodMode::OnScreenKeyboard) ||
           (userInterface->addonInfo()->uiType() == UIType::PhyscialKeyboard &&
            inputMethodMode == InputMethodMode::PhysicalKeyboard);
}

void UserInterfaceManager::updateAvailability() {
    FCITX_D();
    auto *instance = d->addonManager_->instance();
    auto *oldUI = d->ui_;
    UserInterface *newUI = nullptr;
    std::string newUIName;
    for (auto &name : d->uis_) {
        auto *ui =
            static_cast<UserInterface *>(d->addonManager_->addon(name, true));
        if (isUserInterfaceValid(ui, instance
                                         ? instance->inputMethodMode()
                                         : InputMethodMode::PhysicalKeyboard)) {
            newUI = ui;
            newUIName = name;
            break;
        }
    }
    if (oldUI != newUI) {
        FCITX_DEBUG() << "Switching UI addon to " << newUIName;
        if (oldUI) {
            oldUI->suspend();
        }
        if (newUI) {
            newUI->resume();
        }
        d->ui_ = newUI;
        d->uiName_ = newUIName;
        if (instance) {
            instance->postEvent(UIChangedEvent());
        }
    }

    updateVirtualKeyboardVisibility();
}

std::string UserInterfaceManager::currentUI() const {
    FCITX_D();
    return d->uiName_;
}

bool UserInterfaceManager::isVirtualKeyboardVisible() const {
    FCITX_D();
    return d->isVirtualKeyboardVisible_;
}

void UserInterfaceManager::showVirtualKeyboard() const {
    FCITX_D();

    auto *ui = d->ui_;
    if (ui == nullptr || ui->addonInfo() == nullptr ||
        ui->addonInfo()->uiType() != UIType::OnScreenKeyboard) {
        return;
    }

    auto *vkui = static_cast<VirtualKeyboardUserInterface *>(ui);
    vkui->showVirtualKeyboard();
}

void UserInterfaceManager::hideVirtualKeyboard() const {
    FCITX_D();

    auto *ui = d->ui_;
    if (ui == nullptr || ui->addonInfo() == nullptr ||
        ui->addonInfo()->uiType() != UIType::OnScreenKeyboard) {
        return;
    }

    auto *vkui = static_cast<VirtualKeyboardUserInterface *>(ui);
    vkui->hideVirtualKeyboard();
}

void UserInterfaceManager::updateVirtualKeyboardVisibility() {
    FCITX_D();
    bool oldVisible = d->isVirtualKeyboardVisible_;
    bool newVisible = false;

    auto *ui = d->ui_;
    if (ui && ui->addonInfo() &&
        ui->addonInfo()->uiType() == UIType::OnScreenKeyboard) {
        auto *vkui = static_cast<VirtualKeyboardUserInterface *>(ui);
        newVisible = vkui->isVirtualKeyboardVisible();
    }

    if (oldVisible != newVisible) {
        d->isVirtualKeyboardVisible_ = newVisible;

        if (auto *instance = d->addonManager_->instance()) {
            instance->postEvent(VirtualKeyboardVisibilityChangedEvent());
        }
    }
}

} // namespace fcitx
