#include <assert.h>

#include <stdbool.h>

#include <stdint.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "cmark.h"

#include "node.h"

#include "buffer.h"

#include "utf8.h"

#include "scanners.h"

#include "render.h"

#define OUT(s, wrap, escaping) renderer->out(renderer, s, wrap, escaping)

#define LIT(s) renderer->out(renderer, s, false, LITERAL)

#define CR() renderer->cr(renderer)

#define BLANKLINE() renderer->blankline(renderer)

#define ENCODED_SIZE 20

#define LISTMARKER_SIZE 20

// Functions to convert cmark_nodes to commonmark strings.

static inline void outc(cmark_renderer *renderer, cmark_escaping escape,

                        int32_t c, unsigned char nextc) {

  bool needs_escaping = false;

  bool follows_digit =

      renderer->buffer->size > 0 &&

      cmark_isdigit(renderer->buffer->ptr[renderer->buffer->size - 1]);

  char encoded[ENCODED_SIZE];

  int options = renderer->options;

  needs_escaping =

      c < 0x80 && escape != LITERAL &&

      ((escape == NORMAL &&

        (c < 0x20 ||

         c == '*' || c == '_' || c == '[' || c == ']' || c == '#' || c == '<' ||

         c == '>' || c == '\\' || c == '`' ||

   (c == '!' && (!nextc || nextc == '[')) ||

         (c == '&' && cmark_isalpha(nextc)) || (c == '!' && nextc == '[') ||

         ((CMARK_OPT_SMART & options) &&

            ((c == '-' && nextc == '-') ||

             (c == '.' && nextc == '.') ||

             c == '"' || c == '\'')) ||

         (renderer->begin_content && (c == '-' || c == '+' || c == '=') &&

          // begin_content doesn't get set to false til we've passed digits

          // at the beginning of line, so...

          !follows_digit) ||

         (renderer->begin_content && (c == '.' || c == ')') && follows_digit &&

          (nextc == 0 || cmark_isspace(nextc))))) ||

       (escape == URL &&

        (c == '`' || c == '<' || c == '>' || cmark_isspace(c) || c == '\\' ||

         c == ')' || c == '(')) ||

       (escape == TITLE &&

        (c == '`' || c == '<' || c == '>' || c == '"' || c == '\\')));

  if (needs_escaping) {

    if (escape == URL && cmark_isspace(c)) {

      // use percent encoding for spaces

      snprintf(encoded, ENCODED_SIZE, "%%%2X", c);

      cmark_strbuf_puts(renderer->buffer, encoded);

      renderer->column += 3;

    } else if (cmark_ispunct(c)) {

      cmark_render_ascii(renderer, "\\");

      cmark_render_code_point(renderer, c);

    } else { // render as entity

      snprintf(encoded, ENCODED_SIZE, "&#%d;", c);

      cmark_strbuf_puts(renderer->buffer, encoded);

      renderer->column += (int)strlen(encoded);

    }

  } else {

    cmark_render_code_point(renderer, c);

  }

}

static int longest_backtick_sequence(const char *code) {

  int longest = 0;

  int current = 0;

  size_t i = 0;

  size_t code_len = strlen(code);

  while (i <= code_len) {

    if (code[i] == '`') {

      current++;

    } else {

      if (current > longest) {

        longest = current;

      }

      current = 0;

    }

    i++;

  }

  return longest;

}

static int shortest_unused_backtick_sequence(const char *code) {

  // note: if the shortest sequence is >= 32, this returns 32

  // so as not to overflow the bit array.

  uint32_t used = 1;

  int current = 0;

  size_t i = 0;

  size_t code_len = strlen(code);

  while (i <= code_len) {

    if (code[i] == '`') {

      current++;

    } else {

      if (current > 0 && current < 32) {

        used |= (1U << current);

      }

      current = 0;

    }

    i++;

  }

  // return number of first bit that is 0:

  i = 0;

  while (i < 32 && used & 1) {

    used = used >> 1;

    i++;

  }

  return (int)i;

}

static bool is_autolink(cmark_node *node) {

  const unsigned char *title;

  const unsigned char *url;

  cmark_node *link_text;

  if (node->type != CMARK_NODE_LINK) {

    return false;

  }

  url = node->as.link.url;

  if (url == NULL || _scan_scheme(url) == 0) {

    return false;

  }

  title = node->as.link.title;

  // if it has a title, we can't treat it as an autolink:

  if (title && title[0]) {

    return false;

  }

  link_text = node->first_child;

  if (link_text == NULL) {

    return false;

  }

  cmark_consolidate_text_nodes(link_text);

  if (strncmp((const char *)url, "mailto:", 7) == 0) {

    url += 7;

  }

  return link_text->data != NULL &&

         strcmp((const char *)url, (char *)link_text->data) == 0;

}

static int S_render_node(cmark_renderer *renderer, cmark_node *node,

                         cmark_event_type ev_type, int options) {

  cmark_node *tmp;

  int list_number;

  cmark_delim_type list_delim;

  size_t numticks;

  bool extra_spaces;

  size_t i;

  bool entering = (ev_type == CMARK_EVENT_ENTER);

  const char *info, *code, *title;

  char fencechar[2] = {'\0', '\0'};

  size_t code_len;

  char listmarker[LISTMARKER_SIZE];

  const char *emph_delim;

  bool first_in_list_item;

  bufsize_t marker_width;

  bool has_nonspace;

  bool allow_wrap = renderer->width > 0 && !(CMARK_OPT_NOBREAKS & options) &&

                    !(CMARK_OPT_HARDBREAKS & options);

  // Don't adjust tight list status til we've started the list.

  // Otherwise we lose the blank line between a paragraph and

  // a following list.

  if (entering) {

    if (node->parent && node->parent->type == CMARK_NODE_ITEM) {

      renderer->in_tight_list_item = node->parent->parent->as.list.tight;

    }

  } else {

    if (node->type == CMARK_NODE_LIST) {

      renderer->in_tight_list_item =

        node->parent &&

        node->parent->type == CMARK_NODE_ITEM &&

        node->parent->parent->as.list.tight;

    }

  }

  switch (node->type) {

  case CMARK_NODE_DOCUMENT:

    break;

  case CMARK_NODE_BLOCK_QUOTE:

    if (entering) {

      LIT("> ");

      renderer->begin_content = true;

      cmark_strbuf_puts(renderer->prefix, "> ");

    } else {

      cmark_strbuf_truncate(renderer->prefix, renderer->prefix->size - 2);

      BLANKLINE();

    }

    break;

  case CMARK_NODE_LIST:

    if (!entering && node->next && (node->next->type == CMARK_NODE_LIST)) {

      // this ensures that a following indented code block or list will be

      // inteprereted correctly.

      CR();

      LIT("<!-- end list -->");

      BLANKLINE();

    }

    break;

  case CMARK_NODE_ITEM:

    if (cmark_node_get_list_type(node->parent) == CMARK_BULLET_LIST) {

      marker_width = 4;

    } else {

      list_number = cmark_node_get_list_start(node->parent);

      list_delim = cmark_node_get_list_delim(node->parent);

      tmp = node;

      while (tmp->prev) {

        tmp = tmp->prev;

        list_number += 1;

      }

      // we ensure a width of at least 4 so

      // we get nice transition from single digits

      // to double

      snprintf(listmarker, LISTMARKER_SIZE, "%d%s%s", list_number,

               list_delim == CMARK_PAREN_DELIM ? ")" : ".",

               list_number < 10 ? "  " : " ");

      marker_width = (bufsize_t)strlen(listmarker);

    }

    if (entering) {

      if (cmark_node_get_list_type(node->parent) == CMARK_BULLET_LIST) {

        LIT("  - ");

        renderer->begin_content = true;

      } else {

        LIT(listmarker);

        renderer->begin_content = true;

      }

      if (node->first_child == NULL) {

        BLANKLINE();

      } else {

        for (i = marker_width; i--;) {

          cmark_strbuf_putc(renderer->prefix, ' ');

        }

      }

    } else {

      cmark_strbuf_truncate(renderer->prefix,

                            renderer->prefix->size - marker_width);

      CR();

    }

    break;

  case CMARK_NODE_HEADING:

    if (entering) {

      for (i = cmark_node_get_heading_level(node); i > 0; i--) {

        LIT("#");

      }

      LIT(" ");

      renderer->begin_content = true;

      renderer->no_linebreaks = true;

    } else {

      renderer->no_linebreaks = false;

      BLANKLINE();

    }

    break;

  case CMARK_NODE_CODE_BLOCK:

    first_in_list_item = node->prev == NULL && node->parent &&

                         node->parent->type == CMARK_NODE_ITEM;

    if (!first_in_list_item) {

      BLANKLINE();

    }

    info = cmark_node_get_fence_info(node);

    fencechar[0] = strchr(info, '`') == NULL ? '`' : '~';

    code = cmark_node_get_literal(node);

    numticks = longest_backtick_sequence(code) + 1;

    if (numticks < 3) {

      numticks = 3;

    }

    for (i = 0; i < numticks; i++) {

      LIT(fencechar);

    }

    LIT(" ");

    OUT(info, false, LITERAL);

    CR();

    OUT(cmark_node_get_literal(node), false, LITERAL);

    CR();

    for (i = 0; i < numticks; i++) {

      LIT(fencechar);

    }

    BLANKLINE();

    break;

  case CMARK_NODE_HTML_BLOCK:

    BLANKLINE();

    OUT(cmark_node_get_literal(node), false, LITERAL);

    BLANKLINE();

    break;

  case CMARK_NODE_CUSTOM_BLOCK:

    BLANKLINE();

    OUT(entering ? cmark_node_get_on_enter(node) : cmark_node_get_on_exit(node),

        false, LITERAL);

    BLANKLINE();

    break;

  case CMARK_NODE_THEMATIC_BREAK:

    BLANKLINE();

    LIT("-----");

    BLANKLINE();

    break;

  case CMARK_NODE_PARAGRAPH:

    if (!entering) {

      BLANKLINE();

    }

    break;

  case CMARK_NODE_TEXT:

    OUT(cmark_node_get_literal(node), allow_wrap, NORMAL);

    break;

  case CMARK_NODE_LINEBREAK:

    if (!(CMARK_OPT_HARDBREAKS & options)) {

      LIT("  ");

    }

    CR();

    break;

  case CMARK_NODE_SOFTBREAK:

    if (CMARK_OPT_HARDBREAKS & options) {

      LIT("  ");

      CR();

    } else if (!renderer->no_linebreaks && renderer->width == 0 &&

               !(CMARK_OPT_HARDBREAKS & options) &&

               !(CMARK_OPT_NOBREAKS & options)) {

      CR();

    } else {

      OUT(" ", allow_wrap, LITERAL);

    }

    break;

  case CMARK_NODE_CODE:

    code = cmark_node_get_literal(node);

    code_len = strlen(code);

    numticks = shortest_unused_backtick_sequence(code);

    has_nonspace = false;

    for (i=0; i < code_len; i++) {

      if (code[i] != ' ') {

        has_nonspace = true;

        break;

      }

    }

    extra_spaces = code_len == 0 ||

            code[0] == '`' || code[code_len - 1] == '`' ||

            (has_nonspace && code[0] == ' ' && code[code_len - 1] == ' ');

    for (i = 0; i < numticks; i++) {

      LIT("`");

    }

    if (extra_spaces) {

      LIT(" ");

    }

    OUT(cmark_node_get_literal(node), allow_wrap, LITERAL);

    if (extra_spaces) {

      LIT(" ");

    }

    for (i = 0; i < numticks; i++) {

      LIT("`");

    }

    break;

  case CMARK_NODE_HTML_INLINE:

    OUT(cmark_node_get_literal(node), false, LITERAL);

    break;

  case CMARK_NODE_CUSTOM_INLINE:

    OUT(entering ? cmark_node_get_on_enter(node) : cmark_node_get_on_exit(node),

        false, LITERAL);

    break;

  case CMARK_NODE_STRONG:

    if (entering) {

      LIT("**");

    } else {

      LIT("**");

    }

    break;

  case CMARK_NODE_EMPH:

    // If we have EMPH(EMPH(x)), we need to use *_x_*

    // because **x** is STRONG(x):

    if (node->parent && node->parent->type == CMARK_NODE_EMPH &&

        node->next == NULL && node->prev == NULL) {

      emph_delim = "_";

    } else {

      emph_delim = "*";

    }

    if (entering) {

      LIT(emph_delim);

    } else {

      LIT(emph_delim);

    }

    break;

  case CMARK_NODE_LINK:

    if (is_autolink(node)) {

      if (entering) {

        LIT("<");

        if (strncmp(cmark_node_get_url(node), "mailto:", 7) == 0) {

          LIT((const char *)cmark_node_get_url(node) + 7);

        } else {

          LIT((const char *)cmark_node_get_url(node));

        }

        LIT(">");

        // return signal to skip contents of node...

        return 0;

      }

    } else {

      if (entering) {

        LIT("[");

      } else {

        LIT("](");

        OUT(cmark_node_get_url(node), false, URL);

        title = cmark_node_get_title(node);

        if (strlen(title) > 0) {

          LIT(" \"");

          OUT(title, false, TITLE);

          LIT("\"");

        }

        LIT(")");

      }

    }

    break;

  case CMARK_NODE_IMAGE:

    if (entering) {

      LIT("![");

    } else {

      LIT("](");

      OUT(cmark_node_get_url(node), false, URL);

      title = cmark_node_get_title(node);

      if (strlen(title) > 0) {

        OUT(" \"", allow_wrap, LITERAL);

        OUT(title, false, TITLE);

        LIT("\"");

      }

      LIT(")");

    }

    break;

  default:

    assert(false);

    break;

  }

  return 1;

}

char *cmark_render_commonmark(cmark_node *root, int options, int width) {

  if (options & CMARK_OPT_HARDBREAKS) {

    // disable breaking on width, since it has

    // a different meaning with OPT_HARDBREAKS

    width = 0;

  }

  return cmark_render(root, options, width, outc, S_render_node);

}