/**
 * Pure normalizers for the ACP snapshot goldens. They replace the
 * non-deterministic values in the two captured surfaces — the stdout JSON-RPC
 * transcript and the persisted session JSONL — with stable tokens, so a golden
 * compare reflects behavior, not run-to-run noise. Kept dependency-free and
 * side-effect-free so they unit-test trivially.
 *
 * Scrubbed: `randomUUID()` session ids → `{{sessionId}}`; the temp `mkdtemp`
 * cwd → `{{cwd}}` (it appears in terminal-card `_meta` and the log header);
 * JSON-RPC request `id` → a stable per-transcript sequence; the log's per-event
 * `time` (epoch ms) and header `createdAt` → 0. NOT scrubbed: the log's `seq`
 * (deterministic — `seq = log.length`, part of the event-log contract).
 *
 * See docs/rfc/implemented/testing/2026-06-19-acp-snapshot-tests.md.
 */

const SESSION_ID = '{{sessionId}}'
const CWD = '{{cwd}}'

/** A UUID v4 string, the shape `randomUUID()` produces for session ids. */
const UUID_RE = /[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}/gi

/** Inputs the normalizers need to recognize a run's volatile values. */
export interface NormalizeContext {
  /** The session id(s) the run issued — replaced with `{{sessionId}}`. */
  sessionIds: string[]
  /** The temp cwd the run used — replaced with `{{cwd}}`. */
  cwd: string
}

/** Replace cwd, session ids, and any stray UUID with stable tokens in a string. */
function scrubString(value: string, ctx: NormalizeContext): string {
  let out = value
  // cwd first (longest, most specific), then explicit session ids, then any
  // residual UUID (covers ids that appear in places we didn't enumerate).
  out = out.split(ctx.cwd).join(CWD)
  for (const id of ctx.sessionIds) out = out.split(id).join(SESSION_ID)
  out = out.replace(UUID_RE, SESSION_ID)
  return out
}

/** Recursively scrub a parsed JSON value (strings replaced; structure kept). */
function scrubValue(value: unknown, ctx: NormalizeContext): unknown {
  if (typeof value === 'string') return scrubString(value, ctx)
  if (Array.isArray(value)) return value.map(v => scrubValue(v, ctx))
  if (value !== null && typeof value === 'object') {
    const out: Record<string, unknown> = {}
    for (const [k, v] of Object.entries(value)) out[k] = scrubValue(v, ctx)
    return out
  }
  return value
}

/**
 * Normalize a raw stdout transcript (newline-delimited JSON-RPC frames) into a
 * stable golden in the SAME shape as the wire: one compact JSON frame per line
 * (NDJSON), with the JSON-RPC `id` rewritten to a per-transcript sequence
 * (1, 2, 3, …) and all volatile strings scrubbed. Throws if any non-empty line
 * is not valid JSON — that doubles as the stdout-purity check (no logger leaked
 * onto the protocol).
 */
export function normalizeStdout(rawStdout: string, ctx: NormalizeContext): string {
  const lines = rawStdout.split('\n').filter(line => line.trim().length > 0)
  // Map each distinct JSON-RPC id (request/response correlate by id) to a stable
  // sequence number, in first-seen order, so id churn doesn't perturb the golden.
  const idSeq = new Map<string, number>()
  const stableId = (id: unknown): number => {
    const key = JSON.stringify(id)
    let n = idSeq.get(key)
    if (n === undefined) { n = idSeq.size + 1; idSeq.set(key, n) }
    return n
  }
  const frames = lines.map((line) => {
    const frame = JSON.parse(line) as Record<string, unknown>
    if ('id' in frame && frame.id !== undefined && frame.id !== null) {
      frame.id = stableId(frame.id)
    }
    return scrubValue(frame, ctx) as Record<string, unknown>
  })
  return frames.map(f => JSON.stringify(f)).join('\n') + '\n'
}

/**
 * Normalize a session JSONL log into a stable golden: the header line's
 * volatile fields (`createdAt`, `id`, `cwd`) and every event's `time` are
 * zeroed/scrubbed, all volatile strings scrubbed, and `seq` is LEFT INTACT
 * (deterministic by contract). Output is JSONL in the same shape as the input —
 * one compact record per line.
 */
export function normalizeSessionLog(rawLog: string, ctx: NormalizeContext): string {
  const lines = rawLog.split('\n').filter(line => line.trim().length > 0)
  const records = lines.map((line) => {
    const record = JSON.parse(line) as Record<string, unknown>
    // Header line: { type: 'session', createdAt, id, cwd, … }.
    if (record.type === 'session') {
      if ('createdAt' in record) record.createdAt = 0
    } else if ('time' in record) {
      // Event line: zero the epoch-ms timestamp; keep seq (deterministic).
      record.time = 0
    }
    return scrubValue(record, ctx) as Record<string, unknown>
  })
  return records.map(r => JSON.stringify(r)).join('\n') + '\n'
}
