Alex2ESP/src/AlexaCapability.h

// One capability of one device: a row of AlexaInterfaces and what this device adds to it. For most interfaces that
// is nothing. A generic controller (RangeController, ModeController, ToggleController) has an instance and the
// names Alexa calls it by, a configuration, and the words Alexa maps to its directives and states.
//   alexa-discovery-objects.html, generic-controllers.html under
//   https://developer.amazon.com/en-US/docs/alexa/device-apis/
#ifndef ALEXA_CAPABILITY_H
#define ALEXA_CAPABILITY_H

#include <Arduino.h>
#include <ArduinoJson.h>
#include <initializer_list>
#include <type_traits>
#include "AlexaInterfaces.h"
#include "AlexaLimits.h"

// What a user says: "open", "close", "raise", "lower" (alexa-discovery-objects.html#action-mapping)
enum class AlexaAction : uint8_t
{
    Open,
    Close,
    Raise,
    Lower,
    SetEcoOn,
    SetEcoOff
};

// What Alexa says about the device: "the blind is open" (alexa-discovery-objects.html#state-mapping). EcoOn and
// EcoOff are for a ToggleController; Low, Empty, Full, Done and Stuck are what Alexa announces a device for.
enum class AlexaState : uint8_t
{
    Open,
    Closed,
    EcoOn,
    EcoOff,
    Low,
    Empty,
    Full,
    Done,
    Stuck
};

// "Alexa.Actions.Open", in program memory
PGM_P alexaActionName(AlexaAction action);

// "Alexa.States.Open", in program memory
PGM_P alexaStateName(AlexaState state);

// The directive Alexa sends for one or more actions. The name of the directive and its payload, the JSON text of
// an object, are kept as pointers and not copied: pass literals. Actions are announced in the order of AlexaAction.
class ActionMapping
{
public:
    ActionMapping() {}

    ActionMapping(std::initializer_list<AlexaAction> actions, const char *directiveName,
                  const char *directivePayload = nullptr)
        : directiveName(directiveName), directivePayload(directivePayload)
    {
        for (AlexaAction action : actions)
        {
            this->actions |= static_cast<uint8_t>(1u << static_cast<uint8_t>(action));
        }
    }

    uint8_t actions = 0; // one bit per AlexaAction
    const char *directiveName = nullptr;
    const char *directivePayload = nullptr; // nullptr or "" for a directive without payload
};

// Writes the "configuration" object of a capability when the device is announced; context is what the sketch
// passed to setConfiguration()
typedef void (*AlexaConfigurationFiller)(JsonObject configuration, void *context);

// "Alexa.RangeController Blind.Lift" for a log line. The namespace is in program memory, where the %s of the log
// cannot read it.
struct AlexaCapabilityName
{
    AlexaCapabilityName(const AlexaInterfaceDesc &row, const char *instance);

    char text[72];
};

// 116 bytes on the heap of an ESP8266, whatever the capability holds. Every setter returns the capability:
//   device->addCapability(AlexaInterfaces::RangeController, "Blind.Lift")
//       ->addFriendlyName("Lift", "en-US").setConfiguration(fillLift).addStateMapping({AlexaState::Closed}, 0.0f);
// What a capability refuses is printed at ERROR with what to change, and leaves the capability as it was. The
// chain goes on after a call that was refused; isValid() is false from then on, and the device leaves the
// capability out of discovery, where Alexa would otherwise learn half of it.
class AlexaCapability
{
public:
    explicit AlexaCapability(const AlexaInterfaceDesc &row, const char *instance = nullptr);
    ~AlexaCapability();

    // It owns copies of its instance and its names
    AlexaCapability(const AlexaCapability &) = delete;
    AlexaCapability &operator=(const AlexaCapability &) = delete;

    const AlexaInterfaceDesc &getRow() const { return *row; }
    AlexaInterfaceType getType() const { return row->interfaceType(); }
    String getTypeString() const { return String(FPSTR(row->ns)); }
    String getVersion() const { return String(FPSTR(row->version)); }

    // "" when the capability has none
    const char *getInstance() const { return instance != nullptr ? instance : ""; }

    bool isRetrievable() const { return retrievable; }
    bool isProactivelyReported() const { return proactivelyReported; }
    bool isNonControllable() const { return nonControllable; }

    // false when a setter has refused what it was given. The reason was printed when it happened.
    bool isValid() const { return valid; }

    // The instance tells the capabilities of one interface on a device apart ("Blind.Lift", "Blind.Tilt"). It is
    // copied. addCapability(row, instance) sets it; this is for a capability that was added by its type.
    AlexaCapability &setInstance(const char *instance);

    // A name of the capability in words. The text is copied, the locale ("en-US") is not: pass a literal.
    AlexaCapability &addFriendlyName(const char *text, const char *locale);

    // A name from the catalog of Alexa, which Alexa translates: AlexaAssets::Setting_Opening of AlexaResources.h,
    // or PSTR("Alexa.Setting.Opening"). Not copied.
    AlexaCapability &addFriendlyAsset(PGM_P assetId);

    AlexaCapability &setRetrievable(bool value);
    AlexaCapability &setProactivelyReported(bool value);

    // true: Alexa reports the state and sends no directive that changes it
    AlexaCapability &setNonControllable(bool value);

    AlexaCapability &setConfiguration(AlexaConfigurationFiller fill, void *context = nullptr);

    // Only for an interface that takes semantics: RangeController, ModeController, ToggleController
    AlexaCapability &addActionMapping(const ActionMapping &mapping);

    // The states a value stands for: a number or a range of a RangeController, the text of a mode or "ON"/"OFF"
    // of a ToggleController. A text is not copied: pass a literal.
    AlexaCapability &addStateMapping(std::initializer_list<AlexaState> states, float value);
    AlexaCapability &addStateMapping(std::initializer_list<AlexaState> states, float minimum, float maximum);
    AlexaCapability &addStateMapping(std::initializer_list<AlexaState> states, const char *value);

    // A number of another type, addStateMapping({AlexaState::Closed}, 0): without this a 0 is as much a text
    // that is missing as it is a number, and the call does not compile
    template <typename Number, typename = typename std::enable_if<std::is_arithmetic<Number>::value>::type>
    AlexaCapability &addStateMapping(std::initializer_list<AlexaState> states, Number value)
    {
        return addStateMapping(states, static_cast<float>(value));
    }

    // Whether a directive with this namespace and instance is for this capability. The instance counts only
    // for an interface that has instances.
    bool matches(const char *ns, const char *directiveInstance) const;

    // Adds the discovery object of the capability to the capabilities of its endpoint. A capability that Alexa
    // would reject the endpoint for, a generic controller without an instance or without a name, adds nothing,
    // prints what is missing and returns false. So does one that is not valid.
    bool toJson(JsonArray capabilities, const char *endpointId) const;

private:
    struct Name
    {
        const char *value;  // the text, a copy on the heap, or the asset id in program memory
        const char *locale; // nullptr for an asset
    };

    enum StateMappingKind : uint8_t
    {
        STATES_TO_VALUE,
        STATES_TO_RANGE,
        STATES_TO_TEXT
    };

    struct StateMapping
    {
        uint16_t states; // one bit per AlexaState
        uint8_t kind;    // StateMappingKind
        union
        {
            float value; // the value, or the lowest of a range
            const char *text;
        };
        float maximum;
    };

    StateMapping *newStateMapping(std::initializer_list<AlexaState> states, StateMappingKind kind);
    AlexaCapability &refused();
    void writeSemantics(JsonObject capability) const;
    void writeNames(JsonObject capability) const;

    const AlexaInterfaceDesc *row; // in program memory, never nullptr
    char *instance = nullptr;      // a copy on the heap
    AlexaConfigurationFiller fillConfiguration = nullptr;
    void *configurationContext = nullptr;
    Name names[ALEX2ESP_MAX_FRIENDLY_NAMES];
    ActionMapping actionMappings[ALEX2ESP_MAX_ACTION_MAPPINGS];
    StateMapping stateMappings[ALEX2ESP_MAX_STATE_MAPPINGS];
    uint8_t nameCount = 0;
    uint8_t actionCount = 0;
    uint8_t stateCount = 0;
    bool retrievable : 1;
    bool proactivelyReported : 1;
    bool nonControllable : 1;
    bool valid : 1;
};

#endif // ALEXA_CAPABILITY_H