#include <cstdio>
#include <cstdint>
#include <cassert>
#include <cstring>

#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/mman.h>

#include <string>
#include <vector>
#include <algorithm>
#include <unordered_map>

#include <zmq.h>

#include <capnp/serialize.h>
#include "cereal/gen/cpp/log.capnp.h"

#include "parser_common.h"

#define DEBUG(...)
// #define DEBUG printf
#define INFO printf


#define MAX_BAD_COUNTER 5

namespace {

uint64_t read_u64_be(const uint8_t* v) {
  return (((uint64_t)v[0] << 56)
          | ((uint64_t)v[1] << 48)
          | ((uint64_t)v[2] << 40)
          | ((uint64_t)v[3] << 32)
          | ((uint64_t)v[4] << 24)
          | ((uint64_t)v[5] << 16)
          | ((uint64_t)v[6] << 8)
          | (uint64_t)v[7]);
}

std::vector<const DBC*> g_dbc;

bool honda_checksum(int address, uint64_t d, int l) {
  int target = (d >> l) & 0xF;

  DEBUG("check checksum %16lx %d", d, l);

  // remove checksum from calculation
  d &= ~(0xFLL << l);

  int s = 0;
  while (address > 0) { s += (address & 0xF); address >>= 4; }
  while (d > 0) { s += (d & 0xF); d >>= 4; }
  s = 8-s;
  s &= 0xF;

  DEBUG("   %d = %d\n", target, s);
  return target == s;
}

struct MessageState {
  uint32_t address;

  std::vector<Signal> parse_sigs;
  std::vector<double> vals;

  uint64_t seen;
  uint64_t check_threshold;

  uint8_t counter;
  uint8_t counter_fail;

  bool parse(uint64_t sec, uint64_t dat) {
    for (int i=0; i < parse_sigs.size(); i++) {
      auto& sig = parse_sigs[i];

      int64_t tmp = (dat >> sig.bo) & ((1 << sig.b2)-1);
      if (sig.is_signed) {
        tmp -= (tmp >> (sig.b2-1)) ? (1<<sig.b2) : 0; //signed
      }

      DEBUG("parse %X %s -> %ld\n", address, sig.name, tmp);

      if (sig.type == SignalType::HONDA_CHECKSUM) {
        if (!honda_checksum(address, dat, sig.bo)) {
          INFO("%X CHECKSUM FAIL\n", address);
          return false;
        }
      } else if (sig.type == SignalType::HONDA_COUNTER) {
        if (!honda_update_counter(tmp)) {
          return false;
        }
      }

      vals[i] = tmp * sig.factor + sig.offset;
    }
    seen = sec;

    return true;
  }


  bool honda_update_counter(int64_t v) {
    uint8_t old_counter = counter;
    counter = v;
    if (((old_counter+1) & 3) != v) {
      counter_fail += 1;
      if (counter_fail > 1) {
        INFO("%X COUNTER FAIL %d -- %d vs %d\n", address, counter_fail, old_counter, (int)v);
      }
      if (counter_fail >= MAX_BAD_COUNTER) {
        return false;
      }
    } else if (counter_fail > 0) {
      counter_fail--;
    }
    return true;
  }

};

class CANParser {
 public:
  CANParser(int abus, const std::string& dbc_name,
            const std::vector<MessageParseOptions> &options,
            const std::vector<SignalParseOptions> &sigoptions)
    : bus(abus) {
    // connect to can on 8006
    context = zmq_ctx_new();
    subscriber = zmq_socket(context, ZMQ_SUB);
    zmq_setsockopt(subscriber, ZMQ_SUBSCRIBE, "", 0);
    zmq_connect(subscriber, "tcp://127.0.0.1:8006");

    for (auto dbci : g_dbc) {
      if (dbci->name == dbc_name) {
        dbc = dbci;
        break;
      }
    }
    assert(dbc);

    for (auto &op : options) {
      MessageState state = {
        .address = op.address,
        // .check_frequency = op.check_frequency,
      };

      // msg is not valid if a message isn't received for 10 consecutive steps
      if (op.check_frequency > 0) {
        state.check_threshold = (1000000000ULL / op.check_frequency) * 10;
      }


      const Msg* msg = NULL;
      for (int i=0; i<dbc->num_msgs; i++) {
        if (dbc->msgs[i].address == op.address) {
          msg = &dbc->msgs[i];
          break;
        }
      }
      if (!msg) {
        fprintf(stderr, "CANParser: could not find message 0x%X in dnc %s\n", op.address, dbc_name.c_str());
        assert(false);
      }

      // track checksums and for this message
      for (int i=0; i<msg->num_sigs; i++) {
        const Signal *sig = &msg->sigs[i];
        if (sig->type == HONDA_CHECKSUM
            || sig->type == HONDA_COUNTER) {
          state.parse_sigs.push_back(*sig);
          state.vals.push_back(0);
        }
      }

      // track requested signals for this message
      for (auto &sigop : sigoptions) {
        if (sigop.address != op.address) continue;

        for (int i=0; i<msg->num_sigs; i++) {
          const Signal *sig = &msg->sigs[i];
          if (strcmp(sig->name, sigop.name) == 0
              && sig->type != HONDA_CHECKSUM
              && sig->type != HONDA_COUNTER) {
            state.parse_sigs.push_back(*sig);
            state.vals.push_back(sigop.default_value);
            break;
          }
        }

      }

      message_states[state.address] = state;
    }
  }

  void UpdateCans(uint64_t sec, const capnp::List<cereal::CanData>::Reader& cans) {
      int msg_count = cans.size();

      DEBUG("got %d messages\n", msg_count);

      // parse the messages
      for (int i = 0; i < msg_count; i++) {
        auto cmsg = cans[i];
        if (cmsg.getSrc() != bus) {
          // DEBUG("skip %d: wrong bus\n", cmsg.getAddress());
          continue;
        }
        auto state_it = message_states.find(cmsg.getAddress());
        if (state_it == message_states.end()) {
          // DEBUG("skip %d: not specified\n", cmsg.getAddress());
          continue;
        }

        if (cmsg.getDat().size() > 8) continue; //shouldnt ever happen
        uint8_t dat[8] = {0};
        memcpy(dat, cmsg.getDat().begin(), cmsg.getDat().size());

        uint64_t p = read_u64_be(dat);

        DEBUG("  proc %X: %lx\n", cmsg.getAddress(), p);

        state_it->second.parse(sec, p);
      }
  }

  void UpdateValid(uint64_t sec) {
    can_valid = true;
    for (auto &kv : message_states) {
      auto &state = kv.second;
      if (state.check_threshold > 0 && (sec - state.seen) > state.check_threshold) {
        if (state.seen > 0) {
          INFO("%X TIMEOUT\n", state.address);
        }
        can_valid = false;
      }
    }
  }

  void update(uint64_t sec, bool wait) {
    int err;

    // recv from can
    zmq_msg_t msg;
    zmq_msg_init(&msg);

    // multiple recv is fine
    bool first = wait;
    while (1) {
      if (first) {
        err = zmq_msg_recv(&msg, subscriber, 0);
        first = false;
      } else {
        err = zmq_msg_recv(&msg, subscriber, ZMQ_DONTWAIT);
      }
      if (err < 0) break;

      // format for board, make copy due to alignment issues, will be freed on out of scope
      auto amsg = kj::heapArray<capnp::word>((zmq_msg_size(&msg) / sizeof(capnp::word)) + 1);
      memcpy(amsg.begin(), zmq_msg_data(&msg), zmq_msg_size(&msg));

      // extract the messages
      capnp::FlatArrayMessageReader cmsg(amsg);
      cereal::Event::Reader event = cmsg.getRoot<cereal::Event>();
      
      auto cans = event.getCan();

      UpdateCans(sec, cans);
    }

    UpdateValid(sec);

  }

  std::vector<SignalValue> query(uint64_t sec) {
    std::vector<SignalValue> ret;

    for (auto &kv : message_states) {
      auto &state = kv.second;
      if (sec != 0 && state.seen != sec) continue;
      
      for (int i=0; i<state.parse_sigs.size(); i++) {
        const Signal &sig = state.parse_sigs[i];
        ret.push_back((SignalValue){
          .address = state.address,
          .name = sig.name,
          .value = state.vals[i],
        });
      }
    }

    return ret;
  }

  bool can_valid = false;

 private:
  const int bus;
  // zmq vars
  void *context = NULL;
  void *subscriber = NULL;

  const DBC *dbc = NULL;
  std::unordered_map<uint32_t, MessageState> message_states;
};

}

void dbc_register(const DBC* dbc) {
  g_dbc.push_back(dbc);
}

extern "C" {

void* can_init(int bus, const char* dbc_name,
              size_t num_message_options, const MessageParseOptions* message_options,
              size_t num_signal_options, const SignalParseOptions* signal_options) {
  CANParser* ret = new CANParser(bus, std::string(dbc_name),
    (message_options ? std::vector<MessageParseOptions>(message_options, message_options+num_message_options)
      : std::vector<MessageParseOptions>{}),
    (signal_options ? std::vector<SignalParseOptions>(signal_options, signal_options+num_signal_options)
      : std::vector<SignalParseOptions>{}));
  return (void*)ret;
}

void can_update(void* can, uint64_t sec, bool wait) {
  CANParser* cp = (CANParser*)can;
  cp->update(sec, wait);
}

size_t can_query(void* can, uint64_t sec, bool *out_can_valid, size_t out_values_size, SignalValue* out_values) {
  CANParser* cp = (CANParser*)can;

  if (out_can_valid) {
    *out_can_valid = cp->can_valid;
  }

  const std::vector<SignalValue> values = cp->query(sec);
  if (out_values) {
    std::copy(values.begin(), values.begin()+std::min(out_values_size, values.size()), out_values);
  }
  return values.size();
};

}

#ifdef TEST

int main(int argc, char** argv) {
  CANParser cp(0, "honda_civic_touring_2016_can",
    std::vector<MessageParseOptions>{
      // address, check_frequency
      {0x14a, 100},
      {0x158, 100},
      {0x17c, 100},
      {0x191, 100},
      {0x1a4, 50},
      {0x326, 10},
      {0x1b0, 50},
      {0x1d0, 50},
      {0x305, 10},
      {0x324, 10},
      {0x405, 3},
      {0x18f, 0},
      {0x130, 0},
      {0x296, 0},
      {0x30c, 0},
    },
    std::vector<SignalParseOptions>{
      //  sig_name, sig_address, default 
      {0x158, "XMISSION_SPEED", 0},
      {0x1d0, "WHEEL_SPEED_FL", 0},
      {0x1d0, "WHEEL_SPEED_FR", 0},
      {0x1d0, "WHEEL_SPEED_RL", 0},
      {0x14a, "STEER_ANGLE", 0},
      {0x18f, "STEER_TORQUE_SENSOR", 0},
      {0x191, "GEAR", 0},
      {0x1b0, "WHEELS_MOVING", 1},
      {0x405, "DOOR_OPEN_FL", 1},
      {0x405, "DOOR_OPEN_FR", 1},
      {0x405, "DOOR_OPEN_RL", 1},
      {0x405, "DOOR_OPEN_RR", 1},
      {0x324, "CRUISE_SPEED_PCM", 0},
      {0x305, "SEATBELT_DRIVER_LAMP", 1},
      {0x305, "SEATBELT_DRIVER_LATCHED", 0},
      {0x17c, "BRAKE_PRESSED", 0},
      {0x130, "CAR_GAS", 0},
      {0x296, "CRUISE_BUTTONS", 0},
      {0x1a4, "ESP_DISABLED", 1},
      {0x30c, "HUD_LEAD", 0},
      {0x1a4, "USER_BRAKE", 0},
      {0x18f, "STEER_STATUS", 5},
      {0x1d0, "WHEEL_SPEED_RR", 0},
      {0x1b0, "BRAKE_ERROR_1", 1},
      {0x1b0, "BRAKE_ERROR_2", 1},
      {0x191, "GEAR_SHIFTER", 0},
      {0x326, "MAIN_ON", 0},
      {0x17c, "ACC_STATUS", 0},
      {0x17c, "PEDAL_GAS", 0},
      {0x296, "CRUISE_SETTING", 0},
      {0x326, "LEFT_BLINKER", 0},
      {0x326, "RIGHT_BLINKER", 0},
      {0x324, "COUNTER", 0},
      {0x17c, "ENGINE_RPM", 0},
    });



  const std::string log_fn = "dats.bin";

  int log_fd = open(log_fn.c_str(), O_RDONLY, 0);
  assert(log_fd >= 0);

  off_t log_size = lseek(log_fd, 0, SEEK_END);
  lseek(log_fd, 0, SEEK_SET);

  void* log_data = mmap(NULL, log_size, PROT_READ, MAP_PRIVATE, log_fd, 0);
  assert(log_data);

  auto words = kj::arrayPtr((const capnp::word*)log_data, log_size/sizeof(capnp::word));
  while (words.size() > 0) {
    capnp::FlatArrayMessageReader reader(words);

    auto evt = reader.getRoot<cereal::Event>();
    auto cans = evt.getCan();

    cp.UpdateCans(0, cans);

    words = kj::arrayPtr(reader.getEnd(), words.end());
  }

  munmap(log_data, log_size);

  close(log_fd);

  return 0;
}

#endif