///|
/// Rendering.
///
/// Output is plain HTML with no external assets: no CDN, no webfont, no math
/// renderer. A worksheet that needs the network to look right is not a
/// worksheet. Exponents use Unicode superscripts, which print correctly in every
/// browser and survive copy-paste into chat.
pub fn escape_html(s : String) -> String {
  let a = replace_all(s, "&", "&")
  let b = replace_all(a, "<", "<")
  let c = replace_all(b, ">", ">")
  replace_all(c, "\"", """)
}

///|
pub fn render_markdown(paper : Paper, title : String) -> String {
  let sb = StringBuilder()
  sb.write_string("# \{title}\n\n")
  sb.write_string(
    "> \{paper.size()} 题 · 种子 \{paper.seed} · 结构 \{paper.request}\n\n",
  )
  for i, it in paper.items {
    sb.write_string("\{i + 1}. \{it.question}\n\n")
  }
  sb.write_string("---\n\n## 答案\n\n")
  for i, it in paper.items {
    sb.write_string("\{i + 1}. \{it.answer_text()}\n")
  }
  sb.to_string()
}

///|
const BASE_CSS : String =
  #|:root { --ink:#1c1c1e; --muted:#6b6b70; --line:#e4e4e7; --accent:#7a4b2a; }
  #|* { box-sizing:border-box; }
  #|body { margin:0; padding:48px 32px 72px; background:#fbfbfa; color:var(--ink);
  #|  font-family:"Source Han Serif SC","Songti SC","Noto Serif CJK SC",Georgia,serif;
  #|  line-height:1.75; }
  #|.sheet { max-width:760px; margin:0 auto; background:#fff; padding:56px 64px 64px;
  #|  border:1px solid var(--line); border-radius:6px; box-shadow:0 1px 2px rgba(0,0,0,.04); }
  #|header { border-bottom:2px solid var(--ink); padding-bottom:16px; margin-bottom:32px; }
  #|h1 { font-size:24px; margin:0 0 6px; letter-spacing:.02em; }
  #|.meta { margin:0; font-size:13px; color:var(--muted);
  #|  font-family:"Inter","Segoe UI",system-ui,sans-serif; }
  #|ol.problems { list-style:none; counter-reset:p; margin:0; padding:0; }
  #|ol.problems li { counter-increment:p; position:relative; padding:14px 0 14px 44px;
  #|  border-bottom:1px dashed var(--line); font-size:17px; }
  #|ol.problems li:last-child { border-bottom:none; }
  #|ol.problems li::before { content:counter(p)"."; position:absolute; left:0; top:14px;
  #|  width:32px; text-align:right; color:var(--muted); font-size:15px; }
  #|.q { font-size:18px; letter-spacing:.01em; }
  #|.tag { display:inline-block; margin-left:10px; padding:1px 7px; border-radius:3px;
  #|  background:#f4f1ec; color:var(--accent); font-size:11px; vertical-align:2px;
  #|  font-family:"Inter","Segoe UI",system-ui,sans-serif; }
  #|footer { margin-top:40px; padding-top:14px; border-top:1px solid var(--line);
  #|  font-size:12px; color:var(--muted);
  #|  font-family:"Inter","Segoe UI",system-ui,sans-serif; }
  #|table { width:100%; border-collapse:collapse; font-size:14px; margin-top:8px; }
  #|th,td { text-align:left; padding:9px 10px; border-bottom:1px solid var(--line);
  #|  vertical-align:top; }
  #|th { font-size:12px; color:var(--muted); font-weight:600; letter-spacing:.04em;
  #|  text-transform:uppercase; font-family:"Inter","Segoe UI",system-ui,sans-serif; }
  #|td.ans { font-size:16px; white-space:nowrap; }
  #|td.note { color:var(--muted); font-size:13px; }
  #|.cert { margin-top:28px; font-size:12px; color:var(--muted); }
  #|.cert summary { cursor:pointer; }
  #|.cert pre { background:#faf9f7; border:1px solid var(--line); border-radius:4px;
  #|  padding:12px 14px; overflow-x:auto; font-size:12px; line-height:1.6;
  #|  font-family:ui-monospace,"Cascadia Code",Menlo,monospace; }
  #|@media print { body { background:#fff; padding:0; } .sheet { border:none;
  #|  box-shadow:none; padding:0; max-width:none; } .pagebreak { page-break-before:always; } }

///|
pub fn render_worksheet(paper : Paper, title : String) -> String {
  let sb = StringBuilder()
  sb.write_string(
    "\n",
  )
  sb.write_string(
    "",
  )
  sb.write_string("
")
  sb.write_string("
\{escape_html(title)}
")
  sb.write_string(
    "\{paper.size()} 题 · 结构 \{paper.request} · 种子 \{paper.seed} · 每题已通过独立复核",
  )
  sb.write_string("
")
  for it in paper.items {
    sb.write_string("
\{escape_html(it.question)}")
    sb.write_string("\{it.level_label()}
")
  }
  sb.write_string(
    "
",
  )
  sb.write_string("
")
  sb.to_string()
}

///|
pub fn render_answer_key(paper : Paper, title : String) -> String {
  let sb = StringBuilder()
  sb.write_string(
    "\n",
  )
  sb.write_string(
    "",
  )
  sb.write_string("
")
  sb.write_string(
    "
\{escape_html(title)} · 答案
",
  )
  sb.write_string(
    "\{paper.size()} 题 · 种子 \{paper.seed} · 难度与依据由结构特征给出",
  )
  sb.write_string("
")
  sb.write_string(
    "",
  )
  sb.write_string("")
  for i, it in paper.items {
    sb.write_string("")
    sb.write_string("")
    sb.write_string("")
    sb.write_string(
      "",
    )
  }
  sb.write_string("
#
答案
难度
命题依据
\{i + 1}
\{escape_html(it.answer_text())}
\{it.level_label()}
\{escape_html(it.reasons_text())}
")
  sb.write_string(
    "
展开复核凭证（每题一行）
",
  )
  for i, it in paper.items {
    sb.write_string(
      "\{i + 1}. \{escape_html(it.signature)}  |  fp=\{escape_html(it.fingerprint)}\n",
    )
  }
  sb.write_string("
")
  sb.write_string(
    "",
  )
  sb.write_string("
")
  sb.to_string()
}

///|
test "answer text is stable and ordered" {
  let schema = match load_schema(SAMPLE_SCHEMA) {
    Ok(s) => s
    Err(e) => abort("schema error: \{e}")
  }
  let pool = generate(schema, 0)
  let paper = match assemble(pool, schema.name, Blueprint::new(3, 5)) {
    Ok(p) => p
    Err(e) => abort(e)
  }
  let key = render_answer_key(paper, "测试卷")
  inspect(key.contains(""), content="true")
  inspect(key.contains("复核凭证"), content="true")
}

///|
test "html escaping blocks tag injection" {
  inspect(escape_html("a&\"c\""), content="a<b>&"c"")
}