Stream.tish

// Incremental, per-actor deck line decode → progressive apply (the streaming counterpart to
// the atomic deck.block path). A non-indented known statement opens a block; indented lines
// extend it. Each line that extends the open block re-applies the growing block, which is
// idempotent per channel/target via applyCoDjTplSource — so you HEAR a remote actor's track
// appear the instant `track …` arrives, then the pattern fills in as `steps …` streams in.
//
// This is what makes "decode a song into live stems one token-line at a time" real, rather
// than waiting for a whole block. Ownership and skill-gating are enforced on every line.

import { applyCoDjTplSource } from '../codj/Merge.tish'
import { coDjLineAllowedForSkills } from '../codj/Skills.tish'

export fn createTplLineStream(actorId, authorId, skillIds) {
  return {
    actorId: actorId,
    authorId: authorId,
    skillIds: skillIds,
    openLines: [],
    hasOpen: false
  }
}

fn lineIndented(line) {
  if (!line || line.length === 0) {
    return false
  }
  let c = line.charAt(0)
  return c === " " || c === "\t"
}

fn topLevelHead(trimmed) {
  let sp = trimmed.indexOf(" ")
  if (sp < 0) {
    return trimmed
  }
  return trimmed.substring(0, sp)
}

// Statements that have an indented body — they stay "open" and re-apply as the body streams.
fn isBlockOpener(head) {
  return head === "track" || head === "clip" || head === "auto" || head === "song" || head === "follow"
}

// Statements that are complete on one line — apply immediately, no open block left dangling.
fn isStandaloneTopLevel(head) {
  return (
    head === "bpm" ||
    head === "launch_quant" ||
    head === "song_seed" ||
    head === "master_mix" ||
    head === "actor_mix" ||
    head === "session_scenes" ||
    head === "session_slot" ||
    head === "xfade" ||
    head === "main_deck" ||
    head === "swing" ||
    head === "scale" ||
    head === "remove_track"
  )
}

fn stripEol(line) {
  let s = line
  while (s.length > 0) {
    let c = s.charAt(s.length - 1)
    if (c === "\n" || c === "\r") {
      s = s.substring(0, s.length - 1)
    } else {
      break
    }
  }
  return s
}

/**
 * Feed one streamed deck line into the actor's stream and apply progressively.
 * Returns { applied: bool, denied: bool, opened: bool }.
 */
export fn tplLineStreamPush(stream, rawLine, project, perfStep) {
  if ((rawLine === null)) {
    return { applied: false, denied: false, opened: false }
  }
  let line = stripEol(String(rawLine))
  let trimmed = line.trim()
  if (trimmed.length === 0 || trimmed.charAt(0) === "#") {
    return { applied: false, denied: false, opened: false }
  }
  if (topLevelHead(trimmed) === "deck" || topLevelHead(trimmed) === "tpl") {
    return { applied: false, denied: false, opened: false }
  }
  if (!coDjLineAllowedForSkills(trimmed, stream.skillIds)) {
    return { applied: false, denied: true, opened: false }
  }

  let opened = false
  if (lineIndented(line)) {
    if (!stream.hasOpen) {
      // body line with no header yet — not committable on its own
      return { applied: false, denied: false, opened: false }
    }
    stream.openLines.push(line)
  } else {
    let head = topLevelHead(trimmed)
    if (isBlockOpener(head)) {
      stream.openLines = [line]
      stream.hasOpen = true
      opened = true
    } else if (isStandaloneTopLevel(head)) {
      let frag1 = "deck 1\n" + line + "\n"
      applyCoDjTplSource(project, frag1, stream.actorId, stream.authorId, perfStep, stream.skillIds)
      stream.openLines = []
      stream.hasOpen = false
      return { applied: true, denied: false, opened: false }
    } else {
      // unknown / unsupported top-level keyword — ignore (stays out of the open block)
      return { applied: false, denied: false, opened: false }
    }
  }

  let frag = "deck 1\n" + stream.openLines.join("\n") + "\n"
  applyCoDjTplSource(project, frag, stream.actorId, stream.authorId, perfStep, stream.skillIds)
  return { applied: true, denied: false, opened: opened }
}

fn tplLineStreamReset(stream) {
  if (!stream) {
    return
  }
  stream.openLines = []
  stream.hasOpen = false
}