// Copyright 2013 Robin Gareus <robin@gareus.org>
// SPDX-License-Identifier: ISC

#include "uris.h"

#include <lv2/atom/atom.h>
#include <lv2/atom/forge.h>
#include <lv2/atom/util.h>
#include <lv2/core/lv2.h>
#include <lv2/ui/ui.h>
#include <lv2/urid/urid.h>

#include <cairo.h>
#include <gdk/gdk.h>
#include <glib-object.h>
#include <glib.h>
#include <gobject/gclosure.h>
#include <gtk/gtk.h>

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

// Drawing area size
#define DAWIDTH (640)
#define DAHEIGHT (200)

/**
   Max continuous points on path.  Many short-path segments are
   expensive|inefficient long paths are not supported by all surfaces (usually
   its a miter - not point - limit, depending on used cairo backend)
*/
#define MAX_CAIRO_PATH (128)

/**
   Representation of the raw audio-data for display (min | max) values for a
   given 'index' position.
*/
typedef struct {
  float data_min[DAWIDTH];
  float data_max[DAWIDTH];

  uint32_t idx;
  uint32_t sub;
} ScoChan;

typedef struct {
  LV2_Atom_Forge forge;
  LV2_URID_Map*  map;
  ScoLV2URIs     uris;

  LV2UI_Write_Function write;
  LV2UI_Controller     controller;

  GtkWidget*     hbox;
  GtkWidget*     vbox;
  GtkWidget*     sep[2];
  GtkWidget*     darea;
  GtkWidget*     btn_pause;
  GtkWidget*     lbl_speed;
  GtkWidget*     lbl_amp;
  GtkWidget*     spb_speed;
  GtkWidget*     spb_amp;
  GtkAdjustment* spb_speed_adj;
  GtkAdjustment* spb_amp_adj;

  ScoChan  chn[2];
  uint32_t stride;
  uint32_t n_channels;
  bool     paused;
  float    rate;
  bool     updating;
} EgScopeUI;

/** Send current UI settings to backend. */
static void
send_ui_state(LV2UI_Handle handle)
{
  EgScopeUI*  ui   = (EgScopeUI*)handle;
  const float gain = gtk_spin_button_get_value(GTK_SPIN_BUTTON(ui->spb_amp));

  // Use local buffer on the stack to build atom
  uint8_t obj_buf[1024];
  lv2_atom_forge_set_buffer(&ui->forge, obj_buf, sizeof(obj_buf));

  // Start a ui:State object
  LV2_Atom_Forge_Frame frame;
  LV2_Atom*            msg =
    (LV2_Atom*)lv2_atom_forge_object(&ui->forge, &frame, 0, ui->uris.ui_State);

  assert(msg);

  // msg[samples-per-pixel] = integer
  lv2_atom_forge_key(&ui->forge, ui->uris.ui_spp);
  lv2_atom_forge_int(&ui->forge, ui->stride);

  // msg[amplitude] = float
  lv2_atom_forge_key(&ui->forge, ui->uris.ui_amp);
  lv2_atom_forge_float(&ui->forge, gain);

  // Finish ui:State object
  lv2_atom_forge_pop(&ui->forge, &frame);

  // Send message to plugin port '0'
  ui->write(ui->controller,
            0,
            lv2_atom_total_size(msg),
            ui->uris.atom_eventTransfer,
            msg);
}

/** Notify backend that UI is closed. */
static void
send_ui_disable(LV2UI_Handle handle)
{
  EgScopeUI* ui = (EgScopeUI*)handle;
  send_ui_state(handle);

  uint8_t obj_buf[64];
  lv2_atom_forge_set_buffer(&ui->forge, obj_buf, sizeof(obj_buf));

  LV2_Atom_Forge_Frame frame;
  LV2_Atom*            msg =
    (LV2_Atom*)lv2_atom_forge_object(&ui->forge, &frame, 0, ui->uris.ui_Off);

  assert(msg);

  lv2_atom_forge_pop(&ui->forge, &frame);
  ui->write(ui->controller,
            0,
            lv2_atom_total_size(msg),
            ui->uris.atom_eventTransfer,
            msg);
}

/**
   Notify backend that UI is active.

   The plugin should send state and enable data transmission.
*/
static void
send_ui_enable(LV2UI_Handle handle)
{
  EgScopeUI* ui = (EgScopeUI*)handle;

  uint8_t obj_buf[64];
  lv2_atom_forge_set_buffer(&ui->forge, obj_buf, sizeof(obj_buf));

  LV2_Atom_Forge_Frame frame;
  LV2_Atom*            msg =
    (LV2_Atom*)lv2_atom_forge_object(&ui->forge, &frame, 0, ui->uris.ui_On);

  assert(msg);

  lv2_atom_forge_pop(&ui->forge, &frame);
  ui->write(ui->controller,
            0,
            lv2_atom_total_size(msg),
            ui->uris.atom_eventTransfer,
            msg);
}

/** Gtk widget callback. */
static gboolean
on_cfg_changed(GtkWidget* widget, gpointer data)
{
  const EgScopeUI* ui = (const EgScopeUI*)data;
  if (!ui->updating) {
    // Only send UI state if the change is from user interaction
    send_ui_state(data);
  }
  return TRUE;
}

/**
   Gdk drawing area draw callback.

   Called in Gtk's main thread and uses Cairo to draw the data.
*/
static gboolean
on_expose_event(GtkWidget* widget, GdkEventExpose* ev, gpointer data)
{
  EgScopeUI*  ui   = (EgScopeUI*)data;
  const float gain = gtk_spin_button_get_value(GTK_SPIN_BUTTON(ui->spb_amp));

  // Get cairo type for the gtk window
  cairo_t* cr = gdk_cairo_create(ui->darea->window);

  // Limit cairo-drawing to exposed area
  cairo_rectangle(cr, ev->area.x, ev->area.y, ev->area.width, ev->area.height);
  cairo_clip(cr);

  // Clear background
  cairo_set_source_rgba(cr, 0.0, 0.0, 0.0, 1.0);
  cairo_rectangle(cr, 0, 0, DAWIDTH, DAHEIGHT * ui->n_channels);
  cairo_fill(cr);

  cairo_set_line_width(cr, 1.0);

  const uint32_t start = ev->area.x;
  const uint32_t end   = ev->area.x + ev->area.width;

  assert(start < DAWIDTH);
  assert(end <= DAWIDTH);
  assert(start < end);
  assert(ui->n_channels <= 2U);

  for (uint32_t c = 0; c < ui->n_channels; ++c) {
    ScoChan* chn = &ui->chn[c];

    /* Drawing area Y-position of given sample-value.
     * Note: cairo-pixel at 0 spans -0.5 .. +0.5, hence (DAHEIGHT / 2.0 -0.5)
     * also the cairo Y-axis points upwards (hence 'minus value')
     *
     * == (   DAHEIGHT * (CHN)        // channel offset
     *      + (DAHEIGHT / 2) - 0.5    // vertical center -- '0'
     *      - (DAHEIGHT / 2) * (VAL) * (GAIN)
     *    )
     */
    const float chn_y_offset = DAHEIGHT * c + DAHEIGHT * 0.5f - 0.5f;
    const float chn_y_scale  = DAHEIGHT * 0.5f * gain;

#define CYPOS(VAL) (chn_y_offset - (VAL) * chn_y_scale)

    cairo_save(cr);

    /* Restrict drawing to current channel area, don't bleed drawing into
       neighboring channels. */
    cairo_rectangle(cr, 0, DAHEIGHT * c, DAWIDTH, DAHEIGHT);
    cairo_clip(cr);

    // Set color of wave-form
    cairo_set_source_rgba(cr, 0.0, 1.0, 0.0, 1.0);

    /* This is a somewhat 'smart' mechanism to plot audio data using
       alternating up/down line-directions.  It works well for both cases:
       1 pixel <= 1 sample and 1 pixel represents more than 1 sample, but
       is not ideal for either. */
    if (start == chn->idx) {
      cairo_move_to(cr, start - 0.5, CYPOS(0));
    } else {
      cairo_move_to(cr, start - 0.5, CYPOS(chn->data_max[start]));
    }

    uint32_t pathlength = 0;
    for (uint32_t i = start; i < end; ++i) {
      if (i == chn->idx) {
        continue;
      }

      if (i % 2) {
        cairo_line_to(cr, i - .5, CYPOS(chn->data_min[i]));
        cairo_line_to(cr, i - .5, CYPOS(chn->data_max[i]));
        ++pathlength;
      } else {
        cairo_line_to(cr, i - .5, CYPOS(chn->data_max[i]));
        cairo_line_to(cr, i - .5, CYPOS(chn->data_min[i]));
        ++pathlength;
      }

      /** Limit the max cairo path length.  This is an optimization trade
          off: too short path: high load CPU/GPU load.  too-long path:
          bad anti-aliasing, or possibly lost points */
      if (pathlength > MAX_CAIRO_PATH) {
        pathlength = 0;
        cairo_stroke(cr);
        if (i % 2) {
          cairo_move_to(cr, i - .5, CYPOS(chn->data_max[i]));
        } else {
          cairo_move_to(cr, i - .5, CYPOS(chn->data_min[i]));
        }
      }
    }

    if (pathlength > 0) {
      cairo_stroke(cr);
    }

    // Draw current position vertical line if display is slow
    if (ui->stride >= ui->rate / 4800.0f || ui->paused) {
      cairo_set_source_rgba(cr, .9, .2, .2, .6);
      cairo_move_to(cr, chn->idx - .5, DAHEIGHT * c);
      cairo_line_to(cr, chn->idx - .5, DAHEIGHT * (c + 1));
      cairo_stroke(cr);
    }

    // Undo the 'clipping' restriction
    cairo_restore(cr);

    // Channel separator
    if (c > 0) {
      cairo_set_source_rgba(cr, .5, .5, .5, 1.0);
      cairo_move_to(cr, 0, DAHEIGHT * c - .5);
      cairo_line_to(cr, DAWIDTH, DAHEIGHT * c - .5);
      cairo_stroke(cr);
    }

    // Zero scale line
    cairo_set_source_rgba(cr, .3, .3, .7, .5);
    cairo_move_to(cr, 0, DAHEIGHT * (c + .5) - .5);
    cairo_line_to(cr, DAWIDTH, DAHEIGHT * (c + .5) - .5);
    cairo_stroke(cr);
  }

  cairo_destroy(cr);
  return TRUE;
}

/**
   Parse raw audio data and prepare for later drawing.

   Note this is a toy example, which is really a waveform display, not an
   oscilloscope.  A serious scope would not display samples as is.

   Signals above ~ 1/10 of the sampling-rate will not yield a useful visual
   display and result in a rather unintuitive representation of the actual
   waveform.

   Ideally the audio-data would be buffered and upsampled here and after that
   written in a display buffer for later use.

   For more information, see
   https://wiki.xiph.org/Videos/Digital_Show_and_Tell
   http://lac.linuxaudio.org/2013/papers/36.pdf
   and https://github.com/x42/sisco.lv2
*/
static int
process_channel(const EgScopeUI* ui,
                ScoChan*         chn,
                const size_t     n_elem,
                float const*     data,
                uint32_t*        idx_start,
                uint32_t*        idx_end)
{
  int overflow = 0;
  *idx_start   = chn->idx;
  for (size_t i = 0; i < n_elem; ++i) {
    if (data[i] < chn->data_min[chn->idx]) {
      chn->data_min[chn->idx] = data[i];
    }
    if (data[i] > chn->data_max[chn->idx]) {
      chn->data_max[chn->idx] = data[i];
    }
    if (++chn->sub >= ui->stride) {
      chn->sub = 0;
      chn->idx = (chn->idx + 1) % DAWIDTH;
      if (chn->idx == 0) {
        ++overflow;
      }
      chn->data_min[chn->idx] = 1.0f;
      chn->data_max[chn->idx] = -1.0f;
    }
  }
  *idx_end = chn->idx;
  return overflow;
}

/**
   Called via port_event() which is called by the host, typically at a rate of
   around 25 FPS.
*/
static void
update_scope(EgScopeUI*    ui,
             const int32_t channel,
             const size_t  n_elem,
             float const*  data)
{
  // Never trust input data which could lead to application failure.
  if (channel < 0 || (uint32_t)channel > ui->n_channels) {
    return;
  }

  // Update state in sync with 1st channel
  if (channel == 0) {
    ui->stride = gtk_spin_button_get_value(GTK_SPIN_BUTTON(ui->spb_speed));
    const bool paused =
      gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(ui->btn_pause));

    if (paused != ui->paused) {
      ui->paused = paused;
      gtk_widget_queue_draw(ui->darea);
    }
  }
  if (ui->paused) {
    return;
  }

  uint32_t idx_start = 0; // Display pixel start
  uint32_t idx_end   = 0; // Display pixel end
  int      overflow  = 0; // Received more audio-data than display-pixel

  // Process this channel's audio-data for display
  ScoChan* chn = &ui->chn[channel];
  overflow     = process_channel(ui, chn, n_elem, data, &idx_start, &idx_end);

  // Signal gtk's main thread to redraw the widget after the last channel
  if ((uint32_t)channel + 1 == ui->n_channels) {
    if (overflow > 1) {
      // Redraw complete widget
      gtk_widget_queue_draw(ui->darea);
    } else if (idx_end > idx_start) {
      // Redraw area between start -> end pixel
      gtk_widget_queue_draw_area(ui->darea,
                                 idx_start - 2,
                                 0,
                                 3 + idx_end - idx_start,
                                 DAHEIGHT * ui->n_channels);
    } else if (idx_end < idx_start) {
      // Wrap-around: redraw area between 0->start AND end->right-end
      gtk_widget_queue_draw_area(ui->darea,
                                 idx_start - 2,
                                 0,
                                 3 + DAWIDTH - idx_start,
                                 DAHEIGHT * ui->n_channels);
      gtk_widget_queue_draw_area(
        ui->darea, 0, 0, idx_end + 1, DAHEIGHT * ui->n_channels);
    }
  }
}

static LV2UI_Handle
instantiate(const LV2UI_Descriptor*   descriptor,
            const char*               plugin_uri,
            const char*               bundle_path,
            LV2UI_Write_Function      write_function,
            LV2UI_Controller          controller,
            LV2UI_Widget*             widget,
            const LV2_Feature* const* features)
{
  EgScopeUI* ui = (EgScopeUI*)calloc(1, sizeof(EgScopeUI));

  if (!ui) {
    fprintf(stderr, "EgScope.lv2 UI: out of memory\n");
    return NULL;
  }

  ui->map = NULL;
  *widget = NULL;

  if (!strcmp(plugin_uri, SCO_URI "#Mono")) {
    ui->n_channels = 1;
  } else if (!strcmp(plugin_uri, SCO_URI "#Stereo")) {
    ui->n_channels = 2;
  } else {
    free(ui);
    return NULL;
  }

  for (int i = 0; features[i]; ++i) {
    if (!strcmp(features[i]->URI, LV2_URID_URI "#map")) {
      ui->map = (LV2_URID_Map*)features[i]->data;
    }
  }

  if (!ui->map) {
    fprintf(stderr, "EgScope.lv2 UI: Host does not support urid:map\n");
    free(ui);
    return NULL;
  }

  // Initialize private data structure
  ui->write      = write_function;
  ui->controller = controller;

  ui->vbox   = NULL;
  ui->hbox   = NULL;
  ui->darea  = NULL;
  ui->stride = 25;
  ui->paused = false;
  ui->rate   = 48000;

  ui->chn[0].idx = 0;
  ui->chn[0].sub = 0;
  ui->chn[1].idx = 0;
  ui->chn[1].sub = 0;
  memset(ui->chn[0].data_min, 0, sizeof(float) * DAWIDTH);
  memset(ui->chn[0].data_max, 0, sizeof(float) * DAWIDTH);
  memset(ui->chn[1].data_min, 0, sizeof(float) * DAWIDTH);
  memset(ui->chn[1].data_max, 0, sizeof(float) * DAWIDTH);

  map_sco_uris(ui->map, &ui->uris);
  lv2_atom_forge_init(&ui->forge, ui->map);

  // Setup UI
  ui->hbox = gtk_hbox_new(FALSE, 0);
  ui->vbox = gtk_vbox_new(FALSE, 0);

  ui->darea = gtk_drawing_area_new();
  gtk_widget_set_size_request(ui->darea, DAWIDTH, DAHEIGHT * ui->n_channels);

  ui->lbl_speed = gtk_label_new("Samples/Pixel");
  ui->lbl_amp   = gtk_label_new("Amplitude");

  ui->sep[0]    = gtk_hseparator_new();
  ui->sep[1]    = gtk_label_new("");
  ui->btn_pause = gtk_toggle_button_new_with_label("Pause");

  ui->spb_speed_adj =
    (GtkAdjustment*)gtk_adjustment_new(25.0, 1.0, 1000.0, 1.0, 5.0, 0.0);
  ui->spb_speed = gtk_spin_button_new(ui->spb_speed_adj, 1.0, 0);

  ui->spb_amp_adj =
    (GtkAdjustment*)gtk_adjustment_new(1.0, 0.1, 6.0, 0.1, 1.0, 0.0);
  ui->spb_amp = gtk_spin_button_new(ui->spb_amp_adj, 0.1, 1);

  gtk_box_pack_start(GTK_BOX(ui->hbox), ui->darea, FALSE, FALSE, 0);
  gtk_box_pack_start(GTK_BOX(ui->hbox), ui->vbox, FALSE, FALSE, 4);

  gtk_box_pack_start(GTK_BOX(ui->vbox), ui->lbl_speed, FALSE, FALSE, 2);
  gtk_box_pack_start(GTK_BOX(ui->vbox), ui->spb_speed, FALSE, FALSE, 2);
  gtk_box_pack_start(GTK_BOX(ui->vbox), ui->sep[0], FALSE, FALSE, 8);
  gtk_box_pack_start(GTK_BOX(ui->vbox), ui->lbl_amp, FALSE, FALSE, 2);
  gtk_box_pack_start(GTK_BOX(ui->vbox), ui->spb_amp, FALSE, FALSE, 2);
  gtk_box_pack_start(GTK_BOX(ui->vbox), ui->sep[1], TRUE, FALSE, 8);
  gtk_box_pack_start(GTK_BOX(ui->vbox), ui->btn_pause, FALSE, FALSE, 2);

  g_signal_connect(
    G_OBJECT(ui->darea), "expose_event", G_CALLBACK(on_expose_event), ui);
  g_signal_connect(
    G_OBJECT(ui->spb_amp), "value-changed", G_CALLBACK(on_cfg_changed), ui);
  g_signal_connect(
    G_OBJECT(ui->spb_speed), "value-changed", G_CALLBACK(on_cfg_changed), ui);

  *widget = ui->hbox;

  /* Send UIOn message to plugin, which will request state and enable message
     transmission. */
  send_ui_enable(ui);

  return ui;
}

static void
cleanup(LV2UI_Handle handle)
{
  EgScopeUI* ui = (EgScopeUI*)handle;
  /* Send UIOff message to plugin, which will save state and disable message
   * transmission. */
  send_ui_disable(ui);
  gtk_widget_destroy(ui->darea);
  free(ui);
}

static int
recv_raw_audio(EgScopeUI* ui, const LV2_Atom_Object* obj)
{
  const LV2_Atom* chan_val = NULL;
  const LV2_Atom* data_val = NULL;
  const int       n_props  = lv2_atom_object_get(
    obj, ui->uris.channelID, &chan_val, ui->uris.audioData, &data_val, NULL);

  if (n_props != 2 || chan_val->type != ui->uris.atom_Int ||
      data_val->type != ui->uris.atom_Vector) {
    // Object does not have the required properties with correct types
    fprintf(stderr, "eg-scope.lv2 UI error: Corrupt audio message\n");
    return 1;
  }

  // Get the values we need from the body of the property value atoms
  const int32_t          chn = ((const LV2_Atom_Int*)chan_val)->body;
  const LV2_Atom_Vector* vec = (const LV2_Atom_Vector*)data_val;
  if (vec->body.child_type != ui->uris.atom_Float) {
    return 1; // Vector has incorrect element type
  }

  // Number of elements = (total size - header size) / element size
  const size_t n_elem =
    ((data_val->size - sizeof(LV2_Atom_Vector_Body)) / sizeof(float));

  // Float elements immediately follow the vector body header
  const float* data = (const float*)(&vec->body + 1);

  // Update display
  update_scope(ui, chn, n_elem, data);
  return 0;
}

static int
recv_ui_state(EgScopeUI* ui, const LV2_Atom_Object* obj)
{
  const LV2_Atom* spp_val  = NULL;
  const LV2_Atom* amp_val  = NULL;
  const LV2_Atom* rate_val = NULL;

  const int n_props = lv2_atom_object_get(obj,
                                          ui->uris.ui_spp,
                                          &spp_val,
                                          ui->uris.ui_amp,
                                          &amp_val,
                                          ui->uris.param_sampleRate,
                                          &rate_val,
                                          NULL);

  if (n_props != 3 || spp_val->type != ui->uris.atom_Int ||
      amp_val->type != ui->uris.atom_Float ||
      rate_val->type != ui->uris.atom_Float) {
    // Object does not have the required properties with correct types
    fprintf(stderr, "eg-scope.lv2 UI error: Corrupt state message\n");
    return 1;
  }

  // Get the values we need from the body of the property value atoms
  const int32_t spp  = ((const LV2_Atom_Int*)spp_val)->body;
  const float   amp  = ((const LV2_Atom_Float*)amp_val)->body;
  const float   rate = ((const LV2_Atom_Float*)rate_val)->body;

  // Disable transmission and update UI
  ui->updating = true;
  gtk_spin_button_set_value(GTK_SPIN_BUTTON(ui->spb_speed), spp);
  gtk_spin_button_set_value(GTK_SPIN_BUTTON(ui->spb_amp), amp);
  ui->updating = false;
  ui->rate     = rate;

  return 0;
}

/**
   Receive data from the DSP-backend.

   This is called by the host, typically at a rate of around 25 FPS.

   Ideally this happens regularly and with relatively low latency, but there
   are no hard guarantees about message delivery.
*/
static void
port_event(LV2UI_Handle handle,
           uint32_t     port_index,
           uint32_t     buffer_size,
           uint32_t     format,
           const void*  buffer)
{
  EgScopeUI*      ui   = (EgScopeUI*)handle;
  const LV2_Atom* atom = (const LV2_Atom*)buffer;

  /* Check type of data received
   *  - format == 0: Control port event (float)
   *  - format > 0:  Message (atom)
   */
  if (format == ui->uris.atom_eventTransfer &&
      lv2_atom_forge_is_object_type(&ui->forge, atom->type)) {
    const LV2_Atom_Object* obj = (const LV2_Atom_Object*)atom;
    if (obj->body.otype == ui->uris.RawAudio) {
      recv_raw_audio(ui, obj);
    } else if (obj->body.otype == ui->uris.ui_State) {
      recv_ui_state(ui, obj);
    }
  }
}

static const LV2UI_Descriptor descriptor = {SCO_URI "#ui",
                                            instantiate,
                                            cleanup,
                                            port_event,
                                            NULL};

LV2_SYMBOL_EXPORT const LV2UI_Descriptor*
lv2ui_descriptor(uint32_t index)
{
  return index == 0 ? &descriptor : NULL;
}