SongEditorHighlight.tish

// Host (Deckard) song-editor HTML highlight — not part of @spacedevin/deck.
import {
  tokenize,
  classifyLine,
  isKeyword,
  isInlineKeyword,
  isStepToken
} from '@spacedevin/deck'
// Build HTML for mirrored deck highlight layer (textarea overlay). All logic in Tish.

fn escapeHtml(s) {
  if ((s === null)) {
    return ""
  }
  let x = String(s).split("&").join("&")
  x = x.split("<").join("&lt;")
  x = x.split(">").join("&gt;")
  return x
}

fn lineIndentAndCore(line) {
  if ((line === null)) {
    return { indent: 0, core: "", tail: "" }
  }
  let a = 0
  while (a < line.length) {
    let c = line.charAt(a)
    if (c === " " || c === "\t") {
      a = a + 1
    } else {
      break
    }
  }
  let trimmed = line.substring(a)
  let b = trimmed.length
  while (b > 0) {
    let c2 = trimmed.charAt(b - 1)
    if (c2 === " " || c2 === "\t" || c2 === "\r") {
      b = b - 1
    } else {
      break
    }
  }
  let core = trimmed.substring(0, b)
  let tail = line.substring(a + core.length)
  return { indent: a, core: core, tail: tail }
}

// HTML for one line (no comment segment; caller appends comment).
fn highlightCoreHtml(core, indentStr, tailStr, activeStep, playing) {
  let html = escapeHtml(indentStr)
  if (core.length === 0) {
    return html + escapeHtml(tailStr)
  }
  let toks = tokenize(core)
  if (toks.length === 0) {
    return html + escapeHtml(core) + escapeHtml(tailStr)
  }
  let cl = classifyLine(core)
  let stepSlotOfTok = {}
  if (cl.kind === "steps") {
    let si = 0
    while (si < cl.stepIndices.length) {
      let ti = cl.stepIndices[si]
      stepSlotOfTok[String(ti)] = si
      si = si + 1
    }
  }
  let pos = 0
  let ti = 0
  while (ti < toks.length) {
    let tok = toks[ti]
    let found = core.indexOf(tok, pos)
    if (found < 0) {
      break
    }
    html = html + escapeHtml(core.substring(pos, found))
    let inner = escapeHtml(tok)
    let slotStr = stepSlotOfTok[String(ti)]
    if (ti === 0 && isKeyword(tok)) {
      let kwClass = "tpl-hl-kw"
      if (cl.kind === "note") {
        kwClass = kwClass + " tpl-hl-note"
      }
      inner = "<span class=\"" + kwClass + "\">" + inner + "</span>"
    } else {
      if (ti > 0 && isInlineKeyword(tok)) {
        inner = "<span class=\"tpl-hl-kw tpl-hl-inline\">" + inner + "</span>"
      } else {
      if (cl.kind === "steps" && slotStr !== null) {
        let slot = slotStr
        let on = tok === "x" || tok === "X" || tok === "1"
        let off = tok === "." || tok === "0"
        if (on || off) {
          let cls = on ? "tpl-hl-st-on" : "tpl-hl-st-off"
          if (playing && slot === activeStep) {
            cls = cls + " tpl-hl-st-act"
          }
          inner = "<span class=\"" + cls + "\">" + inner + "</span>"
        }
      }
      }
    }
    html = html + inner
    pos = found + tok.length
    ti = ti + 1
  }
  html = html + escapeHtml(core.substring(pos))
  html = html + escapeHtml(tailStr)
  return html
}

export fn tplDocumentToHighlightHtml(source, playbackStep, playing, lastAppliedLineCount, lastAppliedAt) {
  let active = Math.floor(playbackStep) % 16
  let src = source
  if ((src === null)) {
    src = ""
  }
  let lines = String(src).split("\n")
  let totalLines = lines.length
  let now = typeof Date !== "undefined" && Date.now ? Date.now() : 0
  let updatedWindowMs = 32000
  let isRecentlyApplied =
    lastAppliedLineCount > 0 &&
    lastAppliedAt > 0 &&
    (now - lastAppliedAt) < updatedWindowMs
  let li = 0
  let out = ""
  while (li < lines.length) {
    let fullLine = lines[li]
    let hash = fullLine.indexOf("#")
    let main = fullLine
    let com = ""
    if (hash >= 0) {
      main = fullLine.substring(0, hash)
      com = fullLine.substring(hash)
    }
    let ic = lineIndentAndCore(main)
    let indentStr = main.substring(0, ic.indent)
    let lineInLastBlock = isRecentlyApplied && (totalLines - li) <= lastAppliedLineCount
    let lineClass = "tpl-hl-line"
    if (lineInLastBlock) {
      lineClass = lineClass + " tpl-hl-updated"
    }
    out = out + "<span class=\"" + lineClass + "\">"
    out = out + highlightCoreHtml(ic.core, indentStr, ic.tail, active, playing)
    if (com.length > 0) {
      out = out + "<span class=\"tpl-hl-comment\">" + escapeHtml(com) + "</span>"
    }
    out = out + "</span>"
    if (li < lines.length - 1) {
      out = out + "\n"
    }
    li = li + 1
  }
  return out
}