bantam-cpp/render.cpp

/* render.cpp — terminal markdown rendering with box-drawing tables. */
#include "bantam.hpp"
#include <array>
#include <cctype>
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <span>
#include <vector>

/* ----------------------------- table helpers -------------------------- */
bool is_table_line(std::string_view line) {
  std::string_view t = line;
  while (!t.empty() && (t.front() == ' ' || t.front() == '\t')) t.remove_prefix(1);
  if (t.find('|') == std::string_view::npos) return false;
  return (t.front() == '|') || (t.back() == '|');
}
static std::string_view trim_spaces(std::string_view s) {
  while (!s.empty() && (s.front() == ' ' || s.front() == '\t')) s.remove_prefix(1);
  return s;
}
static bool is_table_sep(const std::vector<std::string> &cells) {
  if (cells.empty()) return false;
  for (auto &c : cells) {
    std::string_view cv = trim_spaces(c);
    bool ok = true;
    for (char ch : cv) if (ch != '-' && ch != ':') { ok = false; break; }
    if (!ok) return false;
  }
  return true;
}
static std::vector<std::string> parse_table_cells(std::string_view line) {
  std::string_view t = line;
  while (!t.empty() && (t.front() == ' ' || t.front() == '\t')) t.remove_prefix(1);
  std::string dup(t);
  while (!dup.empty() && (dup.back() == '\n' || dup.back() == '\r')) dup.pop_back();
  if (!dup.empty() && dup.front() == '|') dup.erase(0, 1);
  if (!dup.empty() && dup.back() == '|') dup.pop_back();
  size_t pipes = 0;
  for (char c : dup) if (c == '|') pipes++;
  std::vector<std::string> cells;
  cells.reserve(pipes + 1);
  std::string cur;
  size_t i = 0;
  while (i <= dup.size()) {
    if (i == dup.size() || dup[i] == '|') {
      cells.push_back(std::string(trim_spaces(cur)));
      cur.clear();
    } else {
      cur += dup[i];
    }
    i++;
  }
  return cells;
}

/* ----------------------------- inline --------------------------------- */
static bool is_word_byte(unsigned char c) {
  return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'z') ||
         (c >= 'A' && c <= 'Z') || c == '_';
}
template<class R>
static void wrap_pairs(std::string &dst, std::string_view src, std::string_view open,
                       std::string_view close, const R& codes,
                       bool boundary = false) {
  size_t olen = open.size(), clen = close.size();
  size_t p = 0;
  while (p < src.size()) {
    size_t o = src.find(open, p);
    if (o == std::string_view::npos) { dst += src.substr(p); break; }
    /* When word boundaries are enforced (the _ / __ rules) an opening
     * delimiter glued to a preceding word character is not an opener. */
    if (boundary && o > 0 && is_word_byte((unsigned char)src[o - 1])) {
      dst += src.substr(p, o - p + olen);
      p = o + olen;
      continue;
    }
    dst += src.substr(p, o - p);
    size_t c = o + olen;
    while (true) {
      c = src.find(close, c);
      if (c == std::string_view::npos) { dst += src.substr(o); break; }
      /* A closing delimiter glued to a following word character is not a
       * closer (e.g. the underscores in file_name_here); keep scanning. */
      if (boundary && c + clen < src.size() &&
          is_word_byte((unsigned char)src[c + clen])) {
        c += clen;
        continue;
      }
      break;
    }
    if (c == std::string_view::npos) break; /* substr(o) already appended */
    std::string_view inner = src.substr(o + olen, c - (o + olen));
    dst += cstr(inner, codes);
    p = c + clen;
  }
}
static void apply_links(std::string &dst, std::string_view src) {
  size_t p = 0;
  while (p < src.size()) {
    size_t lb = src.find('[', p);
    if (lb == std::string_view::npos) { dst += src.substr(p); break; }
    size_t rb = src.find(']', lb);
    if (rb == std::string_view::npos || rb + 1 >= src.size() || src[rb + 1] != '(') {
      dst += src.substr(p, lb - p + 1); p = lb + 1; continue;
    }
    size_t rp = src.find(')', rb + 2);
    if (rp == std::string_view::npos) { dst += src.substr(p); break; }
    std::string_view text = src.substr(lb + 1, rb - (lb + 1));
    std::string_view url = src.substr(rb + 2, rp - (rb + 2));
    dst += src.substr(p, lb - p);
    std::string wt = cstr(text, std::array{4, 36});
    dst += wt;
    std::string wu = cstr(url, std::array{2});
    dst += "(" + wu + ")";
    p = rp + 1;
  }
}
static std::string render_inline(std::string_view s) {
  if (!g_col) return std::string(s);
  if (s.empty()) return "";
  std::vector<std::string> codes;
  std::string step1;
  size_t p = 0;
  while (p < s.size()) {
    if (s[p] == '`') {
      size_t start = p + 1;
      size_t end = s.find('`', start);
      if (end != std::string_view::npos && end > start) {
        std::string_view ctext = s.substr(start, end - start);
        std::string ct = cstr(ctext, std::array{33});
        codes.push_back(ct);
        str_appendf(step1, "\x01%zu\x01", codes.size() - 1);
        p = end + 1;
        continue;
      }
      step1 += s[p]; p++;
    } else {
      step1 += s[p]; p++;
    }
  }
  std::string s2; apply_links(s2, step1);
  std::string s3; wrap_pairs(s3, s2, "***", "***", std::array{1, 3});
  std::string s4; wrap_pairs(s4, s3, "___", "___", std::array{1, 3});
  std::string s5; wrap_pairs(s5, s4, "**", "**", std::array{1});
  std::string s6; wrap_pairs(s6, s5, "__", "__", std::array{1}, true);
  std::string s7; wrap_pairs(s7, s6, "*", "*", std::array{3});
  std::string s8; wrap_pairs(s8, s7, "_", "_", std::array{3}, true);
  std::string s9; wrap_pairs(s9, s8, "~~", "~~", std::array{9});
  std::string out;
  size_t q = 0;
  while (q < s9.size()) {
    if (s9[q] == '\x01') {
      size_t e = s9.find('\x01', q + 1);
      if (e != std::string::npos) {
        int idx = to_int_val(std::string_view(s9).substr(q + 1, e - (q + 1)), -1);
        if (idx >= 0 && idx < (int)codes.size()) out += codes[idx];
        q = e + 1; continue;
      }
    }
    out += s9[q]; q++;
  }
  return out;
}

/* ----------------------------- line ----------------------------------- */
static int indent_spaces(std::string_view line) {
  int n = 0;
  while (n < (int)line.size() && line[n] == ' ') n++;
  return n;
}
void render_md_line_print(std::string_view line, MdState &st) {
  if (!g_col) { printf("%s\n", std::string(line).c_str()); return; }
  std::string_view t = trim_spaces(line);
  if (t.size() >= 3 && t.substr(0, 3) == "```") {
    if (!st.in_code) {
      st.in_code = true;
      std::string_view lang = t.substr(3);
      while (!lang.empty() && lang.front() == ' ') lang.remove_prefix(1);
      std::string title;
      if (!lang.empty()) title = sfmt(" [ %s ]", std::string(lang).c_str());
      std::string s = "───" + title;
      for (int i = 0; i < 40; i++) s += "─";
      std::string h = cstr(s, std::array{2});
      printf("%s\n", h.c_str());
    } else {
      st.in_code = false;
      std::string s;
      for (int i = 0; i < 50; i++) s += "─";
      std::string h = cstr(s, std::array{2});
      printf("%s\n", h.c_str());
    }
    return;
  }
  if (st.in_code) {
    std::string pre = cstr("  ", std::array{2});
    std::string body = cstr(line, std::array{32});
    printf("%s%s\n", pre.c_str(), body.c_str());
    return;
  }
  if (t == "---" || t == "***" || t == "___" || t == "----" || t == "------") {
    std::string s;
    for (int i = 0; i < 50; i++) s += "─";
    std::string h = cstr(s, std::array{2});
    printf("%s\n", h.c_str());
    return;
  }
  if (!t.empty() && t[0] == '#') {
    int lvl = 0;
    while (lvl < (int)t.size() && t[lvl] == '#') lvl++;
    if (lvl < (int)t.size() && t[lvl] == ' ') {
      std::string_view htext = trim_spaces(t.substr(lvl));
      if (lvl == 1) { std::string a = cstr("■ ", std::array{35}); std::string b = cstr(htext, std::array{1, 36}); printf("%s%s\n", a.c_str(), b.c_str()); }
      else if (lvl == 2) { std::string a = cstr("▲ ", std::array{35}); std::string b = cstr(htext, std::array{1, 36}); printf("%s%s\n", a.c_str(), b.c_str()); }
      else if (lvl == 3) { std::string a = cstr("● ", std::array{35}); std::string b = cstr(htext, std::array{1, 32}); printf("%s%s\n", a.c_str(), b.c_str()); }
      else if (lvl == 4) { std::string a = cstr("◆ ", std::array{35}); std::string b = cstr(htext, std::array{1, 33}); printf("%s%s\n", a.c_str(), b.c_str()); }
      else { std::string b = cstr(htext, std::array{1}); printf("%s\n", b.c_str()); }
      return;
    }
  }
  if (!t.empty() && t[0] == '>') {
    std::string_view q = trim_spaces(t.substr(1));
    std::string bar = cstr("▎ ", std::array{34});
    std::string body = render_inline(q);
    std::string cbody = cstr(body, std::array{3});
    printf("%s%s\n", bar.c_str(), cbody.c_str());
    return;
  }
  if (t.size() >= 6 && (t.substr(0, 6) == "- [ ] " || t.substr(0, 6) == "* [ ] ")) {
    int ind = indent_spaces(line);
    std::string box = cstr("☐ ", std::array{33});
    std::string rest = render_inline(t.substr(6));
    printf("%*s%s%s\n", ind, "", box.c_str(), rest.c_str());
    return;
  }
  if (t.size() >= 6 && (t.substr(0, 6) == "- [x] " || t.substr(0, 6) == "* [x] " ||
                        t.substr(0, 6) == "- [X] " || t.substr(0, 6) == "* [X] ")) {
    int ind = indent_spaces(line);
    std::string box = cstr("☑ ", std::array{32});
    std::string rest = render_inline(t.substr(6));
    printf("%*s%s%s\n", ind, "", box.c_str(), rest.c_str());
    return;
  }
  if (t.size() >= 2 && (t.substr(0, 2) == "- " || t.substr(0, 2) == "* " || t.substr(0, 2) == "+ ")) {
    int ind = indent_spaces(line);
    std::string bullet = cstr("• ", std::array{36});
    std::string rest = render_inline(t.substr(2));
    printf("%*s%s%s\n", ind, "", bullet.c_str(), rest.c_str());
    return;
  }
  std::string_view num = t;
  while (!num.empty() && std::isdigit((unsigned char)num.front())) num.remove_prefix(1);
  if (!num.empty() && num.front() == '.' && num.size() > 1 && num[1] == ' ') {
    int ind = indent_spaces(line);
    size_t nlen = num.data() - t.data();
    std::string_view nstr = t.substr(0, nlen);
    std::string bullet = cstr(nstr, std::array{33});
    std::string rest = render_inline(t.substr(nlen + 2));
    printf("%*s%s %s\n", ind, "", bullet.c_str(), rest.c_str());
    return;
  }
  std::string r = render_inline(line);
  printf("%s\n", r.c_str());
}

/* ----------------------------- table ---------------------------------- */
static std::vector<std::string> wrap_cell(std::string_view s, int width) {
  std::vector<std::string> lines;
  if (width <= 0) { lines.push_back(""); return lines; }
  std::string copy(s);
  std::vector<std::string> blocks;
  std::string cur;
  size_t p = 0;
  while (p < copy.size()) {
    if (copy.compare(p, 4, "<br>") == 0) { blocks.push_back(cur); cur.clear(); p += 4; continue; }
    if (copy.compare(p, 5, "<br/>") == 0) { blocks.push_back(cur); cur.clear(); p += 5; continue; }
    if (copy.compare(p, 6, "<br />") == 0) { blocks.push_back(cur); cur.clear(); p += 6; continue; }
    cur += copy[p]; p++;
  }
  if (!cur.empty() || blocks.empty()) blocks.push_back(cur);
  std::vector<std::string> wrapped;
  for (auto &cl : blocks) {
    std::vector<std::string> words;
    size_t wp = 0;
    while (wp < cl.size()) {
      while (wp < cl.size() && cl[wp] == ' ') wp++;
      if (wp >= cl.size()) break;
      size_t ws = wp;
      while (wp < cl.size() && cl[wp] != ' ') wp++;
      words.push_back(cl.substr(ws, wp - ws));
    }
    std::string curline;
    for (auto &word : words) {
      int wlen = visible_len(word);
      if (wlen > width) {
        std::string w = word;
        size_t wi = 0;
        while (wi < w.size()) {
          if (!curline.empty()) { wrapped.push_back(curline); curline.clear(); }
          std::string chunk;
          int clen = 0;
          size_t ci = wi;
          while (ci < w.size() && clen < width) {
            if (w[ci] == 0x1b) {
              size_t j = ci + 1;
              if (j < w.size() && w[j] == '[') {
                j++;
                while (j < w.size() && !(w[j] >= 0x40 && w[j] <= 0x7e)) j++;
                if (j < w.size()) j++;
              }
              chunk += w.substr(ci, j - ci); ci = j;
              continue;
            }
            size_t pl; int cp = utf8_decode((const unsigned char *)(w.data() + ci), w.size() - ci, &pl);
            chunk += w.substr(ci, pl); ci += pl; clen += rune_width(cp);
          }
          wrapped.push_back(chunk);
          wi = ci;
        }
        continue;
      }
      int curlen = visible_len(curline);
      if (curline.empty()) curline = word;
      else if (curlen + 1 + wlen <= width) { curline += ' '; curline += word; }
      else { wrapped.push_back(curline); curline = word; }
    }
    if (!curline.empty()) wrapped.push_back(curline);
  }
  if (wrapped.empty()) wrapped.push_back("");
  return wrapped;
}

static void print_row(int num_cols, const std::vector<int> &col_widths,
                      const std::vector<std::string> &cells, bool is_header) {
  std::string s = "│";
  for (int i = 0; i < num_cols; i++) {
    std::string_view txt = (i < (int)cells.size()) ? std::string_view(cells[i]) : std::string_view();
    int pad = col_widths[i] - visible_len(txt);
    if (pad < 0) pad = 0;
    std::string cell = " ";
    cell.append(txt);
    cell.append((size_t)pad + 1, ' ');
    if (is_header) { std::string cc = cstr(cell, std::array{1}); s += cc; }
    else { std::string cc = cstr(cell, std::array{2}); s += cc; }
    s += "│";
  }
  std::string h = cstr(s, std::array{2});
  printf("%s\n", h.c_str());
}

void render_table_print(const std::vector<std::string> &lines) {
  if (lines.empty()) return;
  std::vector<std::vector<std::string>> rows_cells;
  std::vector<std::string> header_cells;
  bool has_header = false;
  for (auto &line : lines) {
    auto cells = parse_table_cells(line);
    if (is_table_sep(cells)) {
      if (!rows_cells.empty() && !has_header) {
        header_cells = std::move(rows_cells.back());
        rows_cells.pop_back();
        has_header = true;
      }
      continue;
    }
    rows_cells.push_back(std::move(cells));
  }
  if (!has_header && lines.size() < 2) {
    MdState st;
    for (auto &ln : lines) render_md_line_print(ln, st);
    return;
  }
  int num_cols = (int)header_cells.size();
  for (auto &row : rows_cells) if ((int)row.size() > num_cols) num_cols = (int)row.size();
  if (num_cols == 0) return;
  if (has_header) { while ((int)header_cells.size() < num_cols) header_cells.push_back(""); }
  std::vector<int> col_widths(num_cols, 0);
  for (int i = 0; i < num_cols; i++) {
    if (has_header) { int vl = visible_len(header_cells[i]); if (vl > col_widths[i]) col_widths[i] = vl; }
    for (auto &row : rows_cells) {
      std::string_view cell = (i < (int)row.size()) ? std::string_view(row[i]) : std::string_view();
      std::string ri = render_inline(cell);
      int vl = visible_len(ri);
      if (vl > col_widths[i]) col_widths[i] = vl;
    }
    if (col_widths[i] < 3) col_widths[i] = 3;
  }
  int max_table_width = term_width();
  if (max_table_width < 20) max_table_width = 80;
  int overhead = 3 * num_cols + 1;
  int avail = max_table_width - overhead;
  if (avail < num_cols * 3) avail = num_cols * 3;
  int tot = 0;
  for (int i = 0; i < num_cols; i++) tot += col_widths[i];
  while (tot > avail) {
    int maxIdx = 0, maxVal = col_widths[0];
    for (int i = 1; i < num_cols; i++) if (col_widths[i] > maxVal) { maxVal = col_widths[i]; maxIdx = i; }
    if (maxVal <= 3) break;
    col_widths[maxIdx]--; tot--;
  }
  {
    std::string s = "┌";
    for (int i = 0; i < num_cols; i++) { for (int j = 0; j < col_widths[i] + 2; j++) s += "─"; if (i < num_cols - 1) s += "┬"; }
    s += "┐";
    std::string h = cstr(s, std::array{2});
    printf("%s\n", h.c_str());
  }
  if (has_header) {
    std::vector<std::vector<std::string>> hw(num_cols);
    int maxh = 1;
    for (int i = 0; i < num_cols; i++) {
      std::string ri = render_inline(header_cells[i]);
      hw[i] = wrap_cell(ri, col_widths[i]);
      if ((int)hw[i].size() > maxh) maxh = (int)hw[i].size();
    }
    for (int lr = 0; lr < maxh; lr++) {
      std::vector<std::string> rowview(num_cols);
      for (int i = 0; i < num_cols; i++) rowview[i] = (lr < (int)hw[i].size()) ? hw[i][lr] : "";
      print_row(num_cols, col_widths, rowview, true);
    }
    {
      std::string s = "├";
      for (int i = 0; i < num_cols; i++) { for (int j = 0; j < col_widths[i] + 2; j++) s += "─"; if (i < num_cols - 1) s += "┼"; }
      s += "┤";
      std::string h = cstr(s, std::array{2});
      printf("%s\n", h.c_str());
    }
  }
  for (auto &row : rows_cells) {
    std::vector<std::vector<std::string>> rw(num_cols);
    int maxr = 1;
    for (int i = 0; i < num_cols; i++) {
      std::string_view cell = (i < (int)row.size()) ? std::string_view(row[i]) : std::string_view();
      std::string ri = render_inline(cell);
      rw[i] = wrap_cell(ri, col_widths[i]);
      if ((int)rw[i].size() > maxr) maxr = (int)rw[i].size();
    }
    for (int lr = 0; lr < maxr; lr++) {
      std::vector<std::string> rowview(num_cols);
      for (int i = 0; i < num_cols; i++) rowview[i] = (lr < (int)rw[i].size()) ? rw[i][lr] : "";
      print_row(num_cols, col_widths, rowview, false);
    }
  }
  {
    std::string s = "└";
    for (int i = 0; i < num_cols; i++) { for (int j = 0; j < col_widths[i] + 2; j++) s += "─"; if (i < num_cols - 1) s += "┴"; }
    s += "┘";
    std::string h = cstr(s, std::array{2});
    printf("%s\n", h.c_str());
  }
}

/* ----------------------------- block ---------------------------------- */
void render_md_print(std::string_view text) {
  if (!g_col) { if (!text.empty()) fputs(std::string(text).c_str(), stdout); return; }
  if (text.empty()) return;
  std::vector<std::string> tbl;
  MdState st;
  size_t start = 0;
  while (true) {
    auto nl = text.find('\n', start);
    std::string_view line = (nl == std::string_view::npos) ? text.substr(start) : text.substr(start, nl - start);
    std::string lstr(line);
    std::string_view t = trim_spaces(lstr);
    bool is_tbl = (!st.in_code && !(t.size() >= 3 && t.substr(0, 3) == "```") && is_table_line(lstr));
    if (is_tbl) {
      tbl.push_back(lstr);
    } else {
      if (!tbl.empty()) { render_table_print(tbl); tbl.clear(); }
      render_md_line_print(lstr, st);
    }
    if (nl == std::string_view::npos) break;
    start = nl + 1;
  }
  if (!tbl.empty()) render_table_print(tbl);
}