#pragma once 

#include <array>
#include "common.h"
#include "esphome/core/component.h"
#include "esphome/core/esphal.h"
#include "esphome/components/i2c/i2c.h"

namespace esphome {
namespace xiaomi {
namespace bslamp2 {

static const uint8_t MSG_LEN = 7;
using MSG = uint8_t[7];

// The commands that are supported by the front panel component.
static const MSG READY_FOR_EV = { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 };
static const MSG TURN_ON      = { 0x02, 0x03, 0x5E, 0x00, 0x64, 0x00, 0x00 };
static const MSG TURN_OFF     = { 0x02, 0x03, 0x0C, 0x00, 0x64, 0x00, 0x00 };
static const MSG SET_LEVEL_1  = { 0x02, 0x03, 0x5E, 0x00, 0x64, 0x00, 0x00 };
static const MSG SET_LEVEL_2  = { 0x02, 0x03, 0x5F, 0x00, 0x64, 0x00, 0x00 };
static const MSG SET_LEVEL_3  = { 0x02, 0x03, 0x5F, 0x80, 0x64, 0x00, 0x00 };
static const MSG SET_LEVEL_4  = { 0x02, 0x03, 0x5F, 0xC0, 0x64, 0x00, 0x00 };
static const MSG SET_LEVEL_5  = { 0x02, 0x03, 0x5F, 0xE0, 0x64, 0x00, 0x00 };
static const MSG SET_LEVEL_6  = { 0x02, 0x03, 0x5F, 0xF0, 0x64, 0x00, 0x00 };
static const MSG SET_LEVEL_7  = { 0x02, 0x03, 0x5F, 0xF8, 0x64, 0x00, 0x00 };
static const MSG SET_LEVEL_8  = { 0x02, 0x03, 0x5F, 0xFC, 0x64, 0x00, 0x00 };
static const MSG SET_LEVEL_9  = { 0x02, 0x03, 0x5F, 0xFE, 0x64, 0x00, 0x00 };
static const MSG SET_LEVEL_10 = { 0x02, 0x03, 0x5F, 0xFF, 0x64, 0x00, 0x00 };

using EVENT = uint16_t;

// Bit flags that are used for specifying an event.
// Events are registered using the following bit pattern
// (bit 1 being the least significant bit):
//
// BITS  INDICATE  PATTERN  RESULT
// 1     status    0        parsing event failed
//                 1        parsing event successful
// 2-3   part      00       part unknown
//                 01       power button
//                 10       color button
//                 11       slider 
// 4-5   type      00       type unknown
//                 01       touch
//                 10       release
// 6-10  slider    00000    level known (or part is not "slider")
//       level     00001    level 1
//                  ...     up to
//                 10101    level 21
//
static const EVENT FLAG_INIT          = 0b0000000000;

static const EVENT FLAG_ERR           = 0b0000000000;
static const EVENT FLAG_OK            = 0b0000000001;

static const EVENT FLAG_PART_SHIFT    = 1;
static const EVENT FLAG_PART_MASK     = 0b0000000110;
static const EVENT FLAG_PART_UNKNOWN  = 0b0000000000;
static const EVENT FLAG_PART_POWER    = 0b0000000010;
static const EVENT FLAG_PART_COLOR    = 0b0000000100;
static const EVENT FLAG_PART_SLIDER   = 0b0000000110;

static const EVENT FLAG_TYPE_SHIFT    = 3;
static const EVENT FLAG_TYPE_MASK     = 0b0000011000;
static const EVENT FLAG_TYPE_UNKNOWN  = 0b0000000000;
static const EVENT FLAG_TYPE_TOUCH    = 0b0000001000;
static const EVENT FLAG_TYPE_RELEASE  = 0b0000010000;

static const EVENT FLAG_LEVEL_SHIFT   = 5;
static const EVENT FLAG_LEVEL_MASK    = 0b1111100000;
static const EVENT FLAG_LEVEL_UNKNOWN = 0b0000000000;

/**
 * This class implements a parser that translates event byte codes from the
 * Xiaomi Mijia Bedside Lamp 2 into usable events.
 */
class FrontPanelEventParser {
public:
    /**
     * Parse the provided event byte code (7 bytes long).
     * Returns a unique integer event code that describes the parsed event.
     */
    EVENT parse(uint8_t *m) {
        EVENT ev = FLAG_INIT;

        // All events use the prefix [04:04:01:00].
        if (m[0] != 0x04 || m[1] != 0x04 || m[2] != 0x01 || m[3] != 0x00) {
            return error_(ev, m, "prefix is not 04:04:01:00");
        }

        // The next byte determines the part that is touched.
        // All remaining bytes specify the event for that part.
        switch (m[4]) {
            case 0x01: // power button
            case 0x02: // color button
                ev |= (m[4] == 0x01 ? FLAG_PART_POWER : FLAG_PART_COLOR);
                if (m[5] == 0x01 && m[6] == (0x02 + m[4])) {
                    ev |= FLAG_TYPE_TOUCH;
                } else if (m[5] == 0x02 && m[6] == (0x03 + m[4])) {
                    ev |= FLAG_TYPE_RELEASE;
                } else {
                    return error_(ev, m, "invalid event type for button");
                }
                break;
            case 0x03: // slider touch
            case 0x04: // slider release
                ev |= FLAG_PART_SLIDER;
                ev |= (m[4] == 0x03 ? FLAG_TYPE_TOUCH : FLAG_TYPE_RELEASE);
                if ((m[6] - m[5] - m[4] - 0x01) != 0) {
                    return error_(ev, m, "invalid slider level crc");
                } else if (m[5] > 0x16 || m[5] < 0x01) {
                    return error_(ev, m, "out of bounds slider value");
                } else {
                    auto level = 0x17 - m[5];
                    ev |= (level << FLAG_LEVEL_SHIFT);
                }
                break;
            default:
                return error_(ev, m, "invalid part id");
                return ev;
        }
        
        // All parsing rules passed. This event is valid.
        ESP_LOGD(TAG, "Front panel I2C event parsed: code=%d", ev);
        ev |= FLAG_OK;

        return ev;
    }

protected:
    bool has_(EVENT ev, EVENT mask, EVENT flag) {
        return (ev & mask) == flag;
    }

    EVENT error_(EVENT ev, uint8_t *m, const char* msg) {
        ESP_LOGE(TAG, "Front panel I2C event error:");
        ESP_LOGE(TAG, "  Error: %s", msg);
        ESP_LOGE(TAG, "  Event: [%02x:%02x:%02x:%02x:%02x:%02x:%02x]",
           m[0], m[1], m[2], m[3], m[4], m[5], m[6]);
        ESP_LOGE(TAG, "  Parsed part: %s",
            (has_(ev, FLAG_PART_MASK, FLAG_PART_POWER) ? "power button" :
             has_(ev, FLAG_PART_MASK, FLAG_PART_COLOR) ? "color button" : 
             has_(ev, FLAG_PART_MASK, FLAG_PART_SLIDER) ? "slider" : "n/a"));
        ESP_LOGE(TAG, "  Parsed event type: %s",
            (has_(ev, FLAG_TYPE_MASK, FLAG_TYPE_TOUCH) ? "touch" :
             has_(ev, FLAG_TYPE_MASK, FLAG_TYPE_RELEASE) ? "release" : "n/a"));
        if (has_(ev, FLAG_PART_MASK, FLAG_PART_SLIDER)) {
            auto level = (ev & FLAG_LEVEL_MASK) >> FLAG_LEVEL_SHIFT;
            if (level > 0) {
                ESP_LOGE(TAG, "  Parsed slider level: %d", level);
            }
        }

        return ev;
    }
};

/**
 * This is a hardware abstraction layer that communicates with with front
 * panel of the Xiaomi Mijia Bedside Lamp 2.
 *
 * It serves as a hub component for other components that implement
 * the actual buttons and slider components.
 */
class FrontPanelHAL : public Component, public i2c::I2CDevice {
public:
    FrontPanelEventParser event;

    /**
     * Set the GPIO pin that is used by the front panel to notify the ESP
     * that a touch/release event can be read using I2C.
     */
    void set_trigger_pin(GPIOPin *pin) { trigger_pin_ = pin; }

    void add_on_event_callback(std::function<void(EVENT)> &&callback) {
        event_callback_.add(std::move(callback));
    }

    void setup() {
        ESP_LOGCONFIG(TAG, "Setting up I2C trigger pin interrupt...");
        trigger_pin_->setup();
        trigger_pin_->attach_interrupt(
            FrontPanelHAL::isr, this, FALLING);
    }

    void dump_config() {
        ESP_LOGCONFIG(TAG, "FrontPanelHAL:");
        LOG_PIN("  I2C interrupt pin: ", trigger_pin_);
    }

    void loop() {
        // Read and publish front panel events.
        auto current_event_id = event_id_;
        if (current_event_id != last_event_id_) {
            last_event_id_ = current_event_id;
            MSG message;
            if (write_bytes_raw(READY_FOR_EV, MSG_LEN) &&
                read_bytes_raw(message, MSG_LEN)) {
                auto ev = event.parse(message);
                if (ev & FLAG_OK) {
                    event_callback_.call(ev);
                }
            }
        }
    }

    /**
     * Sets the front panel illumination to the provided level (0.0 - 1.0).
     *
     * Level 0.0 means: turn off the front panel illumination.
     * The other levels are translated to one of the available levels,
     * represented by the level indicator (i.e. the illumination of the
     * slider bar.)
     */
    void set_light_level(float level) {
        if (level == 0.0f)
            write_bytes_raw(TURN_OFF, MSG_LEN);
        else if (level < 0.15)
            write_bytes_raw(SET_LEVEL_1, MSG_LEN);
        else if (level < 0.25)
            write_bytes_raw(SET_LEVEL_2, MSG_LEN);
        else if (level < 0.35)
            write_bytes_raw(SET_LEVEL_3, MSG_LEN);
        else if (level < 0.45)
            write_bytes_raw(SET_LEVEL_4, MSG_LEN);
        else if (level < 0.55)
            write_bytes_raw(SET_LEVEL_5, MSG_LEN);
        else if (level < 0.65)
            write_bytes_raw(SET_LEVEL_6, MSG_LEN);
        else if (level < 0.75)
            write_bytes_raw(SET_LEVEL_7, MSG_LEN);
        else if (level < 0.85)
            write_bytes_raw(SET_LEVEL_8, MSG_LEN);
        else if (level < 0.95)
            write_bytes_raw(SET_LEVEL_9, MSG_LEN);
        else
            write_bytes_raw(SET_LEVEL_10, MSG_LEN);
    }

protected:
    GPIOPin *trigger_pin_;
    static void isr(FrontPanelHAL *store);
    volatile int event_id_ = 0;
    int last_event_id_ = 0;
    CallbackManager<void(EVENT)> event_callback_{};
};

/**
 * This ISR is used to handle IRQ triggers from the front panel.
 *
 * The front panel pulls the trigger pin low for a short period of time
 * when a new event is available. All we do here to handle the interrupt,
 * is increment a simple event id counter. The main loop of the component
 * will take care of actually reading and processing the event.
 */
void ICACHE_RAM_ATTR HOT FrontPanelHAL::isr(FrontPanelHAL *store) {
    store->event_id_++;
}

} // namespace bslamp2
} // namespace xiaomi
} // namespace esphome