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// Copyright 2014-2016 David Robillard <d@drobilla.net>
// SPDX-License-Identifier: ISC

#include "./uris.h"

#include "lv2/atom/atom.h"
#include "lv2/atom/util.h"
#include "lv2/core/lv2.h"
#include "lv2/core/lv2_util.h"
#include "lv2/log/log.h"
#include "lv2/log/logger.h"
#include "lv2/midi/midi.h"
#include "lv2/urid/urid.h"

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

enum { FIFTHS_IN = 0, FIFTHS_OUT = 1 };

typedef struct {
  // Features
  LV2_URID_Map*  map;
  LV2_Log_Logger logger;

  // Ports
  const LV2_Atom_Sequence* in_port;
  LV2_Atom_Sequence*       out_port;

  // URIs
  FifthsURIs uris;
} Fifths;

static void
connect_port(LV2_Handle instance, uint32_t port, void* data)
{
  Fifths* self = (Fifths*)instance;
  switch (port) {
  case FIFTHS_IN:
    self->in_port = (const LV2_Atom_Sequence*)data;
    break;
  case FIFTHS_OUT:
    self->out_port = (LV2_Atom_Sequence*)data;
    break;
  default:
    break;
  }
}

static LV2_Handle
instantiate(const LV2_Descriptor*     descriptor,
            double                    rate,
            const char*               path,
            const LV2_Feature* const* features)
{
  // Allocate and initialise instance structure.
  Fifths* self = (Fifths*)calloc(1, sizeof(Fifths));
  if (!self) {
    return NULL;
  }

  // Scan host features for URID map
  // clang-format off
  const char*  missing = lv2_features_query(
    features,
    LV2_LOG__log,  &self->logger.log, false,
    LV2_URID__map, &self->map,        true,
    NULL);
  // clang-format on

  lv2_log_logger_set_map(&self->logger, self->map);
  if (missing) {
    lv2_log_error(&self->logger, "Missing feature <%s>\n", missing);
    free(self);
    return NULL;
  }

  map_fifths_uris(self->map, &self->uris);

  return (LV2_Handle)self;
}

static void
cleanup(LV2_Handle instance)
{
  free(instance);
}

static void
run(LV2_Handle instance, uint32_t sample_count)
{
  Fifths*     self = (Fifths*)instance;
  FifthsURIs* uris = &self->uris;

  // Struct for a 3 byte MIDI event, used for writing notes
  typedef struct {
    LV2_Atom_Event event;
    uint8_t        msg[3];
  } MIDINoteEvent;

  // Initially self->out_port contains a Chunk with size set to capacity

  // Get the capacity
  const uint32_t out_capacity = self->out_port->atom.size;

  // Write an empty Sequence header to the output
  lv2_atom_sequence_clear(self->out_port);
  self->out_port->atom.type = self->in_port->atom.type;

  // Read incoming events
  LV2_ATOM_SEQUENCE_FOREACH (self->in_port, ev) {
    if (ev->body.type == uris->midi_Event) {
      const uint8_t* const msg = (const uint8_t*)(ev + 1);
      switch (lv2_midi_message_type(msg)) {
      case LV2_MIDI_MSG_NOTE_ON:
      case LV2_MIDI_MSG_NOTE_OFF:
        // Forward note to output
        lv2_atom_sequence_append_event(self->out_port, out_capacity, ev);

        if (msg[1] <= 127 - 7) {
          // Make a note one 5th (7 semitones) higher than input
          MIDINoteEvent fifth;

          // Could simply do fifth.event = *ev here instead...
          fifth.event.time.frames = ev->time.frames; // Same time
          fifth.event.body.type   = ev->body.type;   // Same type
          fifth.event.body.size   = ev->body.size;   // Same size

          fifth.msg[0] = msg[0];     // Same status
          fifth.msg[1] = msg[1] + 7; // Pitch up 7 semitones
          fifth.msg[2] = msg[2];     // Same velocity

          // Write 5th event
          lv2_atom_sequence_append_event(
            self->out_port, out_capacity, &fifth.event);
        }
        break;
      default:
        // Forward all other MIDI events directly
        lv2_atom_sequence_append_event(self->out_port, out_capacity, ev);
        break;
      }
    }
  }
}

static const void*
extension_data(const char* uri)
{
  return NULL;
}

static const LV2_Descriptor descriptor = {EG_FIFTHS_URI,
                                          instantiate,
                                          connect_port,
                                          NULL, // activate,
                                          run,
                                          NULL, // deactivate,
                                          cleanup,
                                          extension_data};

LV2_SYMBOL_EXPORT
const LV2_Descriptor*
lv2_descriptor(uint32_t index)
{
  return index == 0 ? &descriptor : NULL;
}