///|
fn html_data_range(range : DataByteRange) -> String {
  "[" +
  range.offset.to_string() +
  ", " +
  (range.offset + range.size).to_string() +
  ")"
}

///|
/// One bounded metadata row. Keep this wording in sync with appendDataEntry.
fn html_data_entry(entry : DataSegment) -> String {
  let out = StringBuilder()
  out.write_string(
    "" +
    entry.index.to_string() +
    "",
  )
  out.write_string(
    "" +
    html_escape(data_mode_text(entry.mode)) +
    "" +
    (match entry.memory_index {
      Some(index) => index.to_string()
      None => "n/a"
    }) +
    "",
  )
  out.write_string(
    "" +
    grouped(entry.payload.size) +
    "" +
    grouped(entry.encoding.size) +
    "",
  )
  out.write_string(
    "
" +
    html_data_range(entry.encoding) +
    "
Payload file range " +
    html_data_range(entry.payload) +
    "
",
  )
  out.write_string(
    match entry.offset_expression {
      Some(range) =>
        "
Offset expression file range " +
        html_data_range(range) +
        "; not_evaluated (includes end).
"
      None => "
Offset expression not_applicable.
"
    },
  )
  out.write_string("
\n")
  out.to_string()
}

///|
/// Static first batch is readable without JavaScript or the chart library.
fn html_data_segments_panel(report : DataSegmentsReport) -> String {
  let out = StringBuilder()
  out.write_string(
    "
Data segment encodings · Current input
File byte ledger · no baseline entry comparison
\n",
  )
  out.write_string("
")
  for
    (label, size) in [
      ("Data complete B", report.section_size),
      ("Payload B", report.payload_size),
      ("Entry metadata B", report.entry_metadata_size),
      ("Section overhead B", report.header_size + report.count_size),
      ("Entries", report.entries.length()),
    ] {
    out.write_string(
      "
" + label + "
" + grouped(size) + "
",
    )
  }
  out.write_string(
    "
Complete data " +
    grouped(report.section_size) +
    " B = payload " +
    grouped(report.payload_size) +
    " B + entry metadata " +
    grouped(report.entry_metadata_size) +
    " B + section overhead " +
    grouped(report.header_size + report.count_size) +
    " B (header " +
    grouped(report.header_size) +
    " B + count field " +
    grouped(report.count_size) +
    " B). Datacount: " +
    (match report.datacount {
      Some(n) => n.to_string()
      None => "absent"
    }) +
    " (independent section; excluded).
\n",
  )
  out.write_string(
    "
" +
    html_escape(data_scope()) +
    "
",
  )
  let entries = report.entries.copy()
  entries.sort_by(fn(a, b) {
    if a.payload.size != b.payload.size {
      b.payload.size - a.payload.size
    } else {
      a.index - b.index
    }
  })
  let shown = if entries.length() < 20 { entries.length() } else { 20 }
  out.write_string(
    "
Showing " +
    shown.to_string() +
    " of " +
    entries.length().to_string() +
    " entries. Printing includes only the displayed subset.
",
  )
  out.write_string(
    "
",
  )
  out.write_string(
    "",
  )
  for i = 0; i < shown; i = i + 1 {
    out.write_string(html_data_entry(entries[i]))
  }
  if entries.is_empty() {
    out.write_string(
      "",
    )
  }
  out.write_string(
    "
Current input only. Payload descending, original index ascending. All ranges are file offsets [start, end). Open a range for initialization details.
Index
Mode
Memory
Payload B
Encoded B
File range
" +
      (if report.section is None {
        "No data section in this input."
      } else {
        "Data section is present with zero entries."
      }) +
      "
\n",
  )
  out.to_string()
}