#include <math.h>

#include <cairo/cairo.h>
#include <pango/pangocairo.h>

#define NICKNAME_TEXT_SIZE  23
#define MESSAGE_TEXT_SIZE   24

#define HPADDING            18
#define VPADDING            8

#define AVATAR_OFFSET       3
#define AVATAR_PADDING      12
#define AVATAR_DIM          75
#define AVATAR_WIDTH        (AVATAR_DIM + AVATAR_PADDING)

#define TAIL_WIDTH          18
#define TAIL_HEIGHT         30

#define MESSAGE_BOX_RADIUS  8
#define MESSAGE_BOX_MIN     160

#define WRAP_WIDTH          400

#define TAIL_PATH           "./resources/tail.png"

#define MAX(x, y) ((x) >= (y)? (x): (y))
#define MIN(x, y) ((x) <= (y)? (x): (y))

typedef unsigned int uint_t;

typedef struct {
  int r, g, b;
} color_t;

color_t COLORS_TABLE[] = {
  /* Nickname colors */
  {0xee, 0x49, 0x28}, /* 0 */
  {0x41, 0xa9, 0x03}, /* 1 */
  {0xe0, 0x96, 0x02}, /* 2 */
  {0x0f, 0x94, 0xed}, /* 3 */
  {0x8f, 0x3b, 0xf7}, /* 4 */
  {0xfc, 0x43, 0x80}, /* 5 */
  {0x00, 0xa1, 0xc4}, /* 6 */
  {0xeb, 0x70, 0x02}, /* 7 */

  /* Message text color */
  {0xff, 0xff, 0xff}, /* 8 */

  /* Message box color */
  {0x2b, 0x2b, 0x2b}  /* 9 */
};

#define COLOR(i) (&COLORS_TABLE[i])

#define C_MESSAGE_TEXT COLOR(8)
#define C_MESSAGE_BOX  COLOR(9)

typedef struct {
  PangoLayout *layout;

  uint_t w, h;
} text_t;

typedef struct {
  unsigned char *data;
  size_t size, allocated;
} buffer_t;

#define FLAG_BOLD    (1 << 0)
#define FLAG_STRIKE  (1 << 1)
#define FLAG_ITALIC  (1 << 2)
#define FLAG_TT      (1 << 3)

typedef struct _node_t {
  uint_t flags;
  buffer_t *buffer;

  struct _node_t *next;
} node_t;

void *malloc_protected(size_t z) {
  void *p;

  if (!(p = malloc(z))) {
    fputs("out of memory.\n", stderr);

    exit(1);
  }

  return p;
}

void *realloc_protected(void *old_p, size_t z) {
  void *p;

  if (!(p = realloc(old_p, z))) {
    fputs("out of memory.\n", stderr);

    exit(1);
  }

  return p;
}

buffer_t *new_buffer() {
  buffer_t *buffer;

  buffer = malloc_protected(sizeof(buffer_t));
 
  buffer->data = NULL;
  buffer->size = 0;
  buffer->allocated = 0;

  return buffer;
}

void free_buffer(buffer_t *buffer) {
  free(buffer->data);
  free(buffer);
}

void buffer_expand(buffer_t *buffer, size_t size) {
  buffer->allocated += size;

  buffer->data = realloc_protected(buffer->data, buffer->allocated);
}

void buffer_append_data(buffer_t *buffer, unsigned char *data, size_t data_length) {
  size_t tail = buffer->size;
 
  buffer->size += data_length;

  if (buffer->size > buffer->allocated)
    buffer_expand(buffer, data_length);

  for (size_t i = 0; i < data_length; i++)
    buffer->data[tail + i] = data[i];
}

#define BUFFER_APPEND(b, s) buffer_append_data(b, s, strlen(s))
#define BUFFER_CONCAT(b1, b2) buffer_append_data(b1, (b2)->data, (b2)->size);

node_t *new_node() {
  node_t *node;

  node = malloc_protected(sizeof(node_t));

  node->flags = 0;
  node->buffer = new_buffer();
  node->next = NULL;

  return node;
}

void free_node(node_t *node) {
  if (node->next)
    free_node(node->next);

  free_buffer(node->buffer);
  free(node);
}

#define SET(flag) {\
  if (tail->flags & FLAG_##flag) {\
    tail = tail->next = new_node();\
    continue;\
  }\
  uint_t flags = tail->flags;\
  tail = tail->next = new_node();\
  tail->flags = flags | FLAG_##flag;\
}

void preprocess_text(buffer_t *buffer, char *text) {
  uint_t state;
  node_t *head;
  node_t *tail;

  head = tail = new_node();

  for (size_t i = 0; i < strlen(text); i++) {
    unsigned char c, nc;

    c = text[i];
    nc = text[i+1];

    if (c == '`') {
      SET(TT);
    } else if (c == '*' && nc == '*') {
      i++;

      SET(BOLD);
    } else if (c == '~' && nc == '~') {
      i++;

      SET(STRIKE);
    } else if (c == '_' && nc == '_') {
      i++;

      SET(ITALIC);
    } else {
      buffer_append_data(tail->buffer, &c, 1);
    }
  }

  if (tail->flags) {
    tail->flags = 0;
  }

  node_t *start = head;

  while (head) {
    if (head->flags & FLAG_BOLD)
      BUFFER_APPEND(buffer, "<b>");
    if (head->flags & FLAG_STRIKE)
      BUFFER_APPEND(buffer, "<s>");
    if (head->flags & FLAG_ITALIC)
      BUFFER_APPEND(buffer, "<i>");
    if (head->flags & FLAG_TT)
      BUFFER_APPEND(buffer, "<tt>");

    BUFFER_CONCAT(buffer, head->buffer);

    if (head->flags & FLAG_TT)
      BUFFER_APPEND(buffer, "</tt>");
    if (head->flags & FLAG_ITALIC)
      BUFFER_APPEND(buffer, "</i>");
    if (head->flags & FLAG_STRIKE)
      BUFFER_APPEND(buffer, "</s>");
    if (head->flags & FLAG_BOLD)
      BUFFER_APPEND(buffer, "</b>");

    head = head->next;
  }

  free_node(start);
}

text_t *new_text(cairo_t *cr, char *s, int size, int weight, int preprocess) {
  text_t *text;
  PangoFontDescription *font_description;
  buffer_t *buffer;

  text = malloc_protected(sizeof(text_t));

  font_description = pango_font_description_from_string("Apple Color Emoji 16,Open Sans 16");
  pango_font_description_set_absolute_size(font_description, size * PANGO_SCALE);
  pango_font_description_set_weight(font_description, weight);

  text->layout = pango_cairo_create_layout(cr);
  pango_layout_set_font_description(text->layout, font_description);
  pango_layout_set_wrap(text->layout, PANGO_WRAP_WORD);
  pango_layout_set_width(text->layout, WRAP_WIDTH * PANGO_SCALE);

  pango_font_description_free(font_description);

  if (preprocess) {
    buffer = new_buffer();
    preprocess_text(buffer, s);

    pango_layout_set_markup(text->layout, buffer->data, buffer->size);

    free_buffer(buffer);
  } else
    pango_layout_set_text(text->layout, s, -1);

  pango_layout_get_pixel_size(text->layout, &text->w, &text->h);

  return text;
}

void free_text(text_t *text) {
  g_object_unref(text->layout);

  free(text);
}

/* TO-DO: do this better */
void get_text_size(char *s, uint_t size, uint_t weight, uint_t *w, uint_t *h, int preprocess) {
  cairo_surface_t *surface;
  cairo_t *cr;

  surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, 1, 1);
  cr = cairo_create(surface);

  text_t *text = new_text(cr, s, size, weight, preprocess);

  *w = text->w;
  *h = text->h;

  free_text(text);
  cairo_destroy(cr);
  cairo_surface_destroy(surface);
}

void select_color(cairo_t *cr, color_t *color) {
  cairo_set_source_rgb(cr, color->r / 255.0F, color->g / 255.0F, color->b / 255.0F);
}

void paste_clipped_image(cairo_t *cr, uint_t x, uint_t y, char *path) {
  cairo_surface_t *surface, *surface2;
  cairo_t *ic;

  surface = cairo_image_surface_create_from_png(path);
  ic = cairo_create(surface);

  cairo_scale(ic, ((double)AVATAR_DIM) / cairo_image_surface_get_width(surface), ((double)AVATAR_DIM) / cairo_image_surface_get_height(surface));
  cairo_set_source_surface(ic, surface, 0, 0);
  cairo_paint(ic);

  cairo_destroy(ic);

  surface2 = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, AVATAR_DIM, AVATAR_DIM);
  ic = cairo_create(surface2);

  cairo_arc(ic, AVATAR_DIM/2, AVATAR_DIM/2, AVATAR_DIM/2, 0, 2*M_PI);
  cairo_clip(ic);
  cairo_new_path(ic); 

  cairo_set_source_surface(ic, surface, 0, 0);
  cairo_paint(ic);

  cairo_set_source_surface(cr, surface2, x, y);
  cairo_paint(cr);

  cairo_destroy(ic);
  cairo_surface_destroy(surface);
  cairo_surface_destroy(surface2); 
}

void rounded_rectangle(cairo_t *cr, uint_t x, uint_t y, uint_t w, uint_t h, uint_t r) {
  cairo_set_fill_rule(cr, CAIRO_FILL_RULE_EVEN_ODD);

  cairo_new_sub_path(cr);
  cairo_arc(cr, x + r, y + r, r, M_PI, 3 * M_PI / 2);
  cairo_arc(cr, x + w - r, y + r, r, 3 *M_PI / 2, 2 * M_PI);
  cairo_arc(cr, x + w - r, y + h - r, r, 0, M_PI / 2);
  cairo_arc(cr, x + r, y + h - r, r, M_PI / 2, M_PI);
  cairo_close_path(cr);

  cairo_fill(cr);
}

void text(cairo_t *cr, uint_t x, uint_t y, text_t *text) {
  cairo_move_to(cr, x, y);
  pango_cairo_update_layout(cr, text->layout);
  pango_cairo_show_layout(cr, text->layout);
}

void paste_image(cairo_t *cr, uint_t x, uint_t y, char *path) {
  cairo_surface_t *surface;

  surface = cairo_image_surface_create_from_png(path);
  cairo_set_source_surface(cr, surface, x, y);
  cairo_paint(cr);

  cairo_surface_destroy(surface);
}

void fit(cairo_surface_t **surface, uint_t width, uint_t height) {
  uint_t image_width, image_height;
  uint_t new_width, new_height;
  double image_ratio, new_ratio;

  cairo_surface_t *surface2;
  cairo_t *cr;

  image_width = cairo_image_surface_get_width(*surface);
  image_height = cairo_image_surface_get_height(*surface);

  new_width = width;
  new_height = height;

  image_ratio = ((double)image_width) / ((double)image_height);
  new_ratio = ((double)width) / ((double)height);

  if (image_ratio > new_ratio)
    new_height = ((double)image_height) / ((double)image_width) * ((double)width);
  else
    new_width = ((double)image_width) / ((double)image_height) * ((double)height);

  surface2 = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, new_width, new_height);
  cr = cairo_create(surface2);

  cairo_scale(cr, ((double)new_width) / ((double)image_width), ((double)new_height) / ((double)image_height));
  cairo_set_source_surface(cr, *surface, 0, 0);
  cairo_paint(cr);

  cairo_destroy(cr);
  cairo_surface_destroy(*surface);

  *surface = surface2;
}

void read_uint(uint_t *r) {
  *r = 0;

  for (uint_t i = 0; i < sizeof(uint_t); i++)
    *r |= ((uint_t)fgetc(stdin)) << (i*8);
}

void read_string(buffer_t *buffer) {
  uint_t length;

  read_uint(&length);
  buffer_expand(buffer, length);

  buffer->size += fread(buffer->data + buffer->size, 1, length, stdin);

  buffer_append_data(buffer, &"\0", 1);
}

main() {
  uint_t avatar_width;
  uint_t image_width;
  uint_t image_height;

  uint_t x, y;
  uint_t w, h;

  cairo_surface_t *surface;
  cairo_t *cr;

  text_t *nickname; 
  text_t *message;
  
  buffer_t *output_path;
  buffer_t *avatar_path;
  buffer_t *username_text;
  uint_t username_color;
  buffer_t *message_text;
  
  uint_t nickname_w, nickname_h;
  uint_t message_w, message_h;

  output_path = new_buffer();
  avatar_path = new_buffer();
  username_text = new_buffer();
  message_text = new_buffer();

  read_string(output_path);
  read_string(avatar_path);
  read_string(username_text);
  read_uint(&username_color);
  read_string(message_text);

  username_color = MIN(username_color, 6);

  get_text_size(username_text->data, NICKNAME_TEXT_SIZE, PANGO_WEIGHT_BOLD, &nickname_w, &nickname_h, 0);
  get_text_size(message_text->data, MESSAGE_TEXT_SIZE, PANGO_WEIGHT_NORMAL, &message_w, &message_h, 1);

  image_width = AVATAR_WIDTH + MAX(message_w, nickname_w) + HPADDING*2;
  image_height = message_h + nickname_h + VPADDING*2;

  if (image_width - AVATAR_WIDTH < MESSAGE_BOX_MIN)
    image_width = AVATAR_WIDTH + MESSAGE_BOX_MIN;

  surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, image_width, image_height+AVATAR_OFFSET);
  cr = cairo_create(surface);

  nickname = new_text(cr, username_text->data, NICKNAME_TEXT_SIZE, PANGO_WEIGHT_BOLD, 0);
  message = new_text(cr, message_text->data, MESSAGE_TEXT_SIZE, PANGO_WEIGHT_NORMAL, 1); 

  free_buffer(username_text);
  free_buffer(message_text);

  x = 0;
  y = image_height - AVATAR_DIM + AVATAR_OFFSET;

  paste_clipped_image(cr, x, y, avatar_path->data);
  
  free_buffer(avatar_path);

  x = AVATAR_WIDTH;
  y = 0;
  w = MAX(message->w, nickname->w) + HPADDING*2;
  h = message->h + nickname->h + VPADDING*2;

  if (w < MESSAGE_BOX_MIN)
    w = MESSAGE_BOX_MIN;

  select_color(cr, C_MESSAGE_BOX);
  rounded_rectangle(cr, x, y, w, h, MESSAGE_BOX_RADIUS);

  x = AVATAR_WIDTH - TAIL_WIDTH + 9;
  y = image_height - TAIL_HEIGHT;

  paste_image(cr, x, y, TAIL_PATH);

  x = AVATAR_WIDTH + HPADDING;
  y = VPADDING / 2;

  select_color(cr, COLOR(username_color));
  text(cr, x, y, nickname);

  x = AVATAR_WIDTH + HPADDING;
  y = nickname->h + VPADDING - 3;

  select_color(cr, C_MESSAGE_TEXT);
  text(cr, x, y, message);

  cairo_destroy(cr);

  fit(&surface, 512, 512);
  cairo_surface_write_to_png(surface, output_path->data);

  free_buffer(output_path);
  cairo_surface_destroy(surface);

  free_text(nickname);
  free_text(message);
}