/*
 * This program source code file is part of SystemK, a library in the KTag project.
 *
 * 🛡️ <https://ktag.clubk.club> 🃞
 *
 * Copyright © 2024-2025 Joseph P. Kearney and the KTag developers.
 *
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Affero General Public License as published by the Free
 * Software Foundation, either version 3 of the License, or (at your option) any
 * later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more
 * details.
 *
 * There should be a copy of the GNU Affero General Public License in the LICENSE
 * file in the root of this repository.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdbool.h>
#include <stdio.h>

#include "SystemK.h"

#define DBQ_PURPLE_TEAM 0b00
#define DBQ_RED_TEAM    0b01
#define DBQ_BLUE_TEAM   0b10
#define DBQ_WHITE_TEAM  0b11

#define DBQ_ZERO_MARK_DURATION_IN_us  400
#define DBQ_ZERO_SPACE_DURATION_IN_us 800
#define DBQ_ONE_MARK_DURATION_IN_us   800
#define DBQ_ONE_SPACE_DURATION_IN_us  400
#define DBQ_TOLERANCE_IN_us           199

#define DBQ_PURPLE_TX_GAP_IN_us 2600
#define DBQ_RED_TX_GAP_IN_us    5000
#define DBQ_BLUE_TX_GAP_IN_us   7400
#define DBQ_WHITE_TX_GAP_IN_us  9800

#define MIN_ZERO_MARK_IN_us  (DBQ_ZERO_MARK_DURATION_IN_us - DBQ_TOLERANCE_IN_us)
#define MAX_ZERO_MARK_IN_us  (DBQ_ZERO_MARK_DURATION_IN_us + DBQ_TOLERANCE_IN_us)
#define MIN_ZERO_SPACE_IN_us (DBQ_ZERO_SPACE_DURATION_IN_us - DBQ_TOLERANCE_IN_us)
#define MAX_ZERO_SPACE_IN_us (DBQ_ZERO_SPACE_DURATION_IN_us + DBQ_TOLERANCE_IN_us)
#define MIN_ONE_MARK_IN_us   (DBQ_ONE_MARK_DURATION_IN_us - DBQ_TOLERANCE_IN_us)
#define MAX_ONE_MARK_IN_us   (DBQ_ONE_MARK_DURATION_IN_us + DBQ_TOLERANCE_IN_us)
#define MIN_ONE_SPACE_IN_us  (DBQ_ONE_SPACE_DURATION_IN_us - DBQ_TOLERANCE_IN_us)
#define MAX_ONE_SPACE_IN_us  (DBQ_ONE_SPACE_DURATION_IN_us + DBQ_TOLERANCE_IN_us)

static const TimedBit_T DBQ_ZERO_MARK = {.symbol = MARK, .duration = DBQ_ZERO_MARK_DURATION_IN_us};
static const TimedBit_T DBQ_ONE_MARK = {.symbol = MARK, .duration = DBQ_ONE_MARK_DURATION_IN_us};
static const TimedBit_T DBQ_ZERO_SPACE = {.symbol = SPACE, .duration = DBQ_ZERO_SPACE_DURATION_IN_us};
static const TimedBit_T DBQ_ONE_SPACE = {.symbol = SPACE, .duration = DBQ_ONE_SPACE_DURATION_IN_us};
static const TimedBit_T DBQ_PURPLE_GAP = {.symbol = SPACE, .duration = DBQ_ZERO_SPACE_DURATION_IN_us + DBQ_PURPLE_TX_GAP_IN_us};
static const TimedBit_T DBQ_RED_GAP = {.symbol = SPACE, .duration = DBQ_ONE_SPACE_DURATION_IN_us + DBQ_RED_TX_GAP_IN_us};
static const TimedBit_T DBQ_BLUE_GAP = {.symbol = SPACE, .duration = DBQ_ZERO_SPACE_DURATION_IN_us + DBQ_BLUE_TX_GAP_IN_us};
static const TimedBit_T DBQ_WHITE_GAP = {.symbol = SPACE, .duration = DBQ_ONE_SPACE_DURATION_IN_us + DBQ_WHITE_TX_GAP_IN_us};
static const TimedBit_T DBQ_END = {.symbol = SPACE, .duration = LAST_PULSE};

static TimedPulseTrain_T Tag_Send_Buffer;
static DecodedPacket_T DBQ_Tag_Received_Buffers[3] =
{
    {.Tag.type = DECODED_PACKET_TYPE_BUFFER_FREE},
    {.Tag.type = DECODED_PACKET_TYPE_BUFFER_FREE},
    {.Tag.type = DECODED_PACKET_TYPE_BUFFER_FREE}
};

static uint_fast16_t Team_To_Ignore = DBQ_WHITE_TEAM;

static inline DecodedPacket_T *Get_Tag_Packet_Buffer(void)
{
    if (DBQ_Tag_Received_Buffers[0].Tag.type == DECODED_PACKET_TYPE_BUFFER_FREE)
    {
        return &DBQ_Tag_Received_Buffers[0];
    }
    else if (DBQ_Tag_Received_Buffers[1].Tag.type == DECODED_PACKET_TYPE_BUFFER_FREE)
    {
        return &DBQ_Tag_Received_Buffers[1];
    }
    else
    {
        // Just use it.
        return &DBQ_Tag_Received_Buffers[2];
    }
}

TimedPulseTrain_T *DBQ_EncodePacket(TagPacket_T *packet)
{
    if (packet->team_ID == DBQ_PURPLE_TEAM)
    {
        Tag_Send_Buffer.bitstream[0] = DBQ_ZERO_MARK;
        Tag_Send_Buffer.bitstream[1] = DBQ_ZERO_SPACE;
        Tag_Send_Buffer.bitstream[2] = DBQ_ZERO_MARK;
        Tag_Send_Buffer.bitstream[3] = DBQ_PURPLE_GAP;
        Tag_Send_Buffer.bitstream[4] = DBQ_ZERO_MARK;
        Tag_Send_Buffer.bitstream[5] = DBQ_ZERO_SPACE;
        Tag_Send_Buffer.bitstream[6] = DBQ_ZERO_MARK;
        Tag_Send_Buffer.bitstream[7] = DBQ_ZERO_SPACE;
        Tag_Send_Buffer.bitstream[8] = DBQ_END;
    }
    else if (packet->team_ID == DBQ_RED_TEAM)
    {
        Team_To_Ignore = DBQ_RED_TEAM;
        
        Tag_Send_Buffer.bitstream[0] = DBQ_ZERO_MARK;
        Tag_Send_Buffer.bitstream[1] = DBQ_ZERO_SPACE;
        Tag_Send_Buffer.bitstream[2] = DBQ_ONE_MARK;
        Tag_Send_Buffer.bitstream[3] = DBQ_RED_GAP;
        Tag_Send_Buffer.bitstream[4] = DBQ_ZERO_MARK;
        Tag_Send_Buffer.bitstream[5] = DBQ_ZERO_SPACE;
        Tag_Send_Buffer.bitstream[6] = DBQ_ONE_MARK;
        Tag_Send_Buffer.bitstream[7] = DBQ_ONE_SPACE;
        Tag_Send_Buffer.bitstream[8] = DBQ_END;
    }
    else if (packet->team_ID == DBQ_BLUE_TEAM)
    {
        Team_To_Ignore = DBQ_BLUE_TEAM;
        
        Tag_Send_Buffer.bitstream[0] = DBQ_ONE_MARK;
        Tag_Send_Buffer.bitstream[1] = DBQ_ONE_SPACE;
        Tag_Send_Buffer.bitstream[2] = DBQ_ZERO_MARK;
        Tag_Send_Buffer.bitstream[3] = DBQ_BLUE_GAP;
        Tag_Send_Buffer.bitstream[4] = DBQ_ONE_MARK;
        Tag_Send_Buffer.bitstream[5] = DBQ_ONE_SPACE;
        Tag_Send_Buffer.bitstream[6] = DBQ_ZERO_MARK;
        Tag_Send_Buffer.bitstream[7] = DBQ_ZERO_SPACE;
        Tag_Send_Buffer.bitstream[8] = DBQ_END;
    }
    else // if (packet->team_ID == DBQ_WHITE_TEAM)
    {
        Tag_Send_Buffer.bitstream[0] = DBQ_ONE_MARK;
        Tag_Send_Buffer.bitstream[1] = DBQ_ONE_SPACE;
        Tag_Send_Buffer.bitstream[2] = DBQ_ONE_MARK;
        Tag_Send_Buffer.bitstream[3] = DBQ_WHITE_GAP;
        Tag_Send_Buffer.bitstream[4] = DBQ_ONE_MARK;
        Tag_Send_Buffer.bitstream[5] = DBQ_ONE_SPACE;
        Tag_Send_Buffer.bitstream[6] = DBQ_ONE_MARK;
        Tag_Send_Buffer.bitstream[7] = DBQ_ONE_SPACE;
        Tag_Send_Buffer.bitstream[8] = DBQ_END;
    }
    
    Tag_Send_Buffer.count = 8;

    return &Tag_Send_Buffer;
}

DecodedPacket_T *DBQ_MaybeDecodePacket(TimedPulseTrain_T *packet)
{
    uint_fast8_t decoded_data = UINT_FAST8_MAX;
    uint_fast8_t consecutive_bits = 0;
    uint_fast8_t ignored_data = UINT_FAST8_MAX;
    
    // Special handling for the purple team.
    uint_fast16_t collisions = 0;
    uint_fast16_t purple_completions = 0;

    // Loop through all the pulses, looking for a match.
    for (uint8_t n = 0; n < packet->count; n += 2)
    {
        // Even pulses are marks; odd pulses are spaces.
        if (consecutive_bits == 0)
        {
            // Perform full checking on the first bit.
            if ((packet->bitstream[n].duration > MIN_ONE_MARK_IN_us) && (packet->bitstream[n].duration < MAX_ONE_MARK_IN_us) &&
                (packet->bitstream[n + 1].duration > MIN_ONE_SPACE_IN_us) && (packet->bitstream[n + 1].duration < MAX_ONE_SPACE_IN_us))
            {
                // This is a "one".
                decoded_data = 2;
                consecutive_bits = 1;
            }
            else if ((packet->bitstream[n].duration > MIN_ZERO_MARK_IN_us) && (packet->bitstream[n].duration < MAX_ZERO_MARK_IN_us) &&
                     (packet->bitstream[n + 1].duration > MIN_ZERO_SPACE_IN_us) && (packet->bitstream[n + 1].duration < MAX_ZERO_SPACE_IN_us))
            {
                // This is a "zero".
                decoded_data = 0;
                consecutive_bits = 1;
            }
            else
            {
                // This mark/space combination is neither a zero or a one; continue.
                collisions++;
            }
        }
        else // consecutive_bits > 0
        {
            // One the second bit, full check the mark, and make sure the space is long enough.
            if ((packet->bitstream[n].duration > MIN_ONE_MARK_IN_us) && (packet->bitstream[n].duration < MAX_ONE_MARK_IN_us) &&
                ((packet->bitstream[n + 1].duration > MIN_ONE_SPACE_IN_us) || (packet->bitstream[n + 1].duration == LAST_PULSE)))
            {
                // This is a "one".
                decoded_data += 1;
                
                if (decoded_data == Team_To_Ignore)
                {
                    // We received a packet we should ignore.   Remember this, and keep looking.
                    ignored_data = decoded_data;
                    decoded_data = UINT_FAST8_MAX;
                    consecutive_bits = 0;
                }
                else if (decoded_data == DBQ_PURPLE_TEAM)
                {
                    // We received a purple packet.  Remember this, and keep looking.
                    purple_completions++;
                    decoded_data = UINT_FAST8_MAX;
                    consecutive_bits = 0;
                }
                else
                {
                    break;
                }
            }
            else if ((packet->bitstream[n].duration > MIN_ZERO_MARK_IN_us) && (packet->bitstream[n].duration < MAX_ZERO_MARK_IN_us) &&
                     ((packet->bitstream[n + 1].duration > MIN_ZERO_SPACE_IN_us) || (packet->bitstream[n + 1].duration == LAST_PULSE)))
            {
                // This is a "zero".
                decoded_data += 0;
                
                if (decoded_data == Team_To_Ignore)
                {
                    // We received a packet we should ignore.   Remember this, and keep looking.
                    ignored_data = decoded_data;
                    decoded_data = UINT_FAST8_MAX;
                    consecutive_bits = 0;
                }
                else if (decoded_data == DBQ_PURPLE_TEAM)
                {
                    // We received a purple packet.  Remember this, and keep looking.
                    purple_completions++;
                    decoded_data = UINT_FAST8_MAX;
                    consecutive_bits = 0;
                }
                else
                {
                    break;
                }
            }
            else
            {
                // This mark/space combination is neither a zero or a one; reset.
                collisions++;
                decoded_data = UINT_FAST8_MAX;
                consecutive_bits = 0;
            }
        }
    }
    
    // If we ignored the only data we received, restore it here.
    if ((ignored_data != UINT_FAST8_MAX) && (decoded_data == UINT_FAST8_MAX))
    {
        decoded_data = ignored_data;
    }
    
    if (purple_completions > 0)
    {
        DecodedPacket_T *Tag_Rx_Buffer = Get_Tag_Packet_Buffer();
        Tag_Rx_Buffer->Tag.type = DECODED_PACKET_TYPE_TAG_RECEIVED;
        Tag_Rx_Buffer->Tag.protocol = DUBUQUE_PROTOCOL;
        Tag_Rx_Buffer->Tag.player_ID = 0;
        Tag_Rx_Buffer->Tag.team_ID = DBQ_PURPLE_TEAM;
        Tag_Rx_Buffer->Tag.damage = 10 * (purple_completions + collisions);
        Tag_Rx_Buffer->Tag.color = COLOR_PURPLE;
        return Tag_Rx_Buffer;
    }
    else if (decoded_data == DBQ_RED_TEAM)
    {
        DecodedPacket_T *Tag_Rx_Buffer = Get_Tag_Packet_Buffer();
        Tag_Rx_Buffer->Tag.type = DECODED_PACKET_TYPE_TAG_RECEIVED;
        Tag_Rx_Buffer->Tag.protocol = DUBUQUE_PROTOCOL;
        Tag_Rx_Buffer->Tag.player_ID = 0;
        Tag_Rx_Buffer->Tag.team_ID = DBQ_RED_TEAM;
        Tag_Rx_Buffer->Tag.damage = 10;
        Tag_Rx_Buffer->Tag.color = COLOR_RED;
        return Tag_Rx_Buffer;
    }
    else if (decoded_data == DBQ_BLUE_TEAM)
    {
        DecodedPacket_T *Tag_Rx_Buffer = Get_Tag_Packet_Buffer();
        Tag_Rx_Buffer->Tag.type = DECODED_PACKET_TYPE_TAG_RECEIVED;
        Tag_Rx_Buffer->Tag.protocol = DUBUQUE_PROTOCOL;
        Tag_Rx_Buffer->Tag.player_ID = 0;
        Tag_Rx_Buffer->Tag.team_ID = DBQ_BLUE_TEAM;
        Tag_Rx_Buffer->Tag.damage = 10;
        Tag_Rx_Buffer->Tag.color = COLOR_BLUE;
        return Tag_Rx_Buffer;
    }
    else if (decoded_data == DBQ_WHITE_TEAM)
    {
        DecodedPacket_T *Tag_Rx_Buffer = Get_Tag_Packet_Buffer();
        Tag_Rx_Buffer->Tag.type = DECODED_PACKET_TYPE_TAG_RECEIVED;
        Tag_Rx_Buffer->Tag.protocol = DUBUQUE_PROTOCOL;
        Tag_Rx_Buffer->Tag.player_ID = 0;
        Tag_Rx_Buffer->Tag.team_ID = DBQ_WHITE_TEAM;
        Tag_Rx_Buffer->Tag.damage = 10;
        Tag_Rx_Buffer->Tag.color = COLOR_WHITE;
        return Tag_Rx_Buffer;
    }

    return NULL;
}

color_t DBQ_GetTeamColor(uint8_t team_ID)
{
    color_t result = COLOR_PURPLE;

    if (team_ID == DBQ_RED_TEAM)
    {
        result = COLOR_RED;
    }
    else if (team_ID == DBQ_BLUE_TEAM)
    {
        result = COLOR_BLUE;
    }
	else if (team_ID == DBQ_WHITE_TEAM)
    {
        result = COLOR_WHITE;
    }
    else
    {
        // Nothing to do.
    }

    return result;
}