// Per-job aggregation over the relay's audit log. The audit log
// records ONE row per relay call (transcribe or analyze); a single
// summary job typically produces 1 transcribe row + N analyze rows
// (one per chunked-analyze window). This module groups those rows by
// X-Recap-Job-Id and computes per-video stats the dashboard renders
// as a sortable / filterable table.
//
// The aggregation is computed on the fly from the in-memory entries
// array — no separate persistence. A typical 30-day window has a few
// thousand audit rows; grouping is O(n) and well under 10 ms.
//
// Output row shape (one per job_id, plus a synthetic row for
// orphaned entries with no job_id):
//   {
//     job_id:            string | null
//     started_at:        ms-epoch (earliest ts across the job's rows)
//     completed_at:      ms-epoch (latest ts)
//     install_id:        short string
//     tier:              "core" | "pro" | "max" | null
//     media_url:         string | null      // from the transcribe row
//     title:             string | null      // ditto
//     audio_seconds:     number | null      // from transcribe row
//     audio_bytes:       number | null      // ditto (bytes downloaded
//                                              by the relay for transcribe-url)
//     transcribe_status: "success" | "error" | "refused" | "missing"
//     transcribe_backend: "gemini" | "hardware" | null
//     transcribe_model:   string | null
//     transcribe_ms:      number | null
//     download_ms:        number | null
//     chunk_count:        number | null     // transcribe-side audio chunks
//     analyze_windows_total:    number     // count of analyze rows
//     analyze_windows_success:  number
//     analyze_windows_failed:   number
//     analyze_backend:   string | null    // dominant backend across analyze rows
//     analyze_model:     string | null    // dominant model across analyze rows
//     analyze_ms:        number          // sum of analyze duration_ms
//     overall_status:    "success" | "partial" | "failed"
//     wall_time_ms:      completed_at - started_at
//     cost_usd:          number (sum across all rows)
//     errors:            string[]        // concatenated short error strings
//     // Derived metrics — pre-computed so the UI can sort by them:
//     transcribe_ms_per_min:  number | null   // transcribe_ms / (audio_seconds/60)
//     transcribe_ms_per_mb:   number | null   // transcribe_ms / (audio_bytes / 1MB)
//     download_ms_per_mb:     number | null
//     analyze_ms_per_min:     number | null
//     analyze_ms_per_mb:      number | null
//   }

const MB = 1024 * 1024;

export function aggregateJobs(entries, opts = {}) {
  // Group by job_id. Entries without job_id become singleton groups
  // keyed by their ts so they still appear in the table (helpful for
  // debugging orphan calls).
  const groups = new Map();
  for (const e of entries) {
    const key = e.job_id || `_orphan_${e.ts}`;
    if (!groups.has(key)) groups.set(key, []);
    groups.get(key).push(e);
  }

  // Optional set of job_ids that have stored output JSONs — passed
  // in from the route layer so the aggregator doesn't have to hit
  // the filesystem itself. Used to set the has_output flag the
  // dashboard reads to show/hide the "View" link.
  const outputIdSet = opts.outputIdSet instanceof Set ? opts.outputIdSet : null;

  const out = [];
  for (const [key, rows] of groups) {
    const row = aggregateOne(key, rows);
    row.has_output = outputIdSet ? outputIdSet.has(row.job_id) : false;
    out.push(row);
  }
  // Newest first by started_at.
  out.sort((a, b) => b.started_at - a.started_at);
  return out;
}

function aggregateOne(key, rows) {
  rows.sort((a, b) => a.ts - b.ts);
  // ts in each audit row is when recordCall() fired — i.e., when the
  // work for that row COMPLETED, not when it started. To recover the
  // user-POV "job start" timestamp we work backwards from the first
  // row's end-time using its duration_ms AND download_ms fields.
  //
  // TX row layout:
  //   ts = download_end + tx_work_end
  //   duration_ms = tx_work_duration (NOT including download)
  //   download_ms = download_duration
  //
  // So: job_start = ts - duration_ms - download_ms.
  //
  // Without including download_ms here, wall_time misses the
  // download phase (which can be 30-60s on a long YouTube fetch).
  // Including it makes wall_time match the operator's intuitive
  // formula: WALL ≈ DL + TX + AN_wall.
  const firstRowDur = Number(rows[0].duration_ms) || 0;
  const firstRowDownload = Number(rows[0].download_ms) || 0;
  const startedAt = rows[0].ts - firstRowDur - firstRowDownload;
  const completedAt = rows[rows.length - 1].ts;

  const tx = rows.find((r) => r.pipeline === "transcribe");
  const analyzeRows = rows.filter((r) => r.pipeline === "analyze");

  const analyzeSuccess = analyzeRows.filter((r) => r.status === "success");
  const analyzeFailed = analyzeRows.filter((r) => r.status !== "success");
  const analyzeMs = analyzeRows.reduce(
    (s, r) => s + (Number(r.duration_ms) || 0),
    0
  );
  // Analyze wall time: elapsed clock time from when the FIRST window
  // started to when the LAST window finished. For a 1-batch parallel
  // analyze (all N windows fire concurrently), this ≈ the slowest
  // single window's duration. For multi-batch (N > concurrency, e.g.
  // 10 windows at concurrency 8 → 2 sequential batches), this spans
  // both batches including any gap. Computed from end-ts minus
  // start-ts (where start-ts = row.ts - row.duration_ms) so it's
  // an accurate measured value, not a predicted one.
  let analyzeWallMs = null;
  if (analyzeRows.length > 0) {
    let minStart = Infinity;
    let maxEnd = -Infinity;
    for (const r of analyzeRows) {
      const end = Number(r.ts) || 0;
      const dur = Number(r.duration_ms) || 0;
      const start = end - dur;
      if (start < minStart) minStart = start;
      if (end > maxEnd) maxEnd = end;
    }
    analyzeWallMs = maxEnd - minStart;
  }
  const analyzeDominantBackend = dominant(
    analyzeSuccess.map((r) => r.backend)
  );
  const analyzeDominantModel = dominant(analyzeSuccess.map((r) => r.model));

  const errors = rows
    .filter((r) => r.error)
    .map((r) => `${r.pipeline}: ${String(r.error).slice(0, 160)}`);

  const txStatus = tx ? tx.status : "missing";
  let overall;
  if (txStatus === "error" || txStatus === "refused" || txStatus === "missing") {
    overall = "failed";
  } else if (txStatus === "partial") {
    // TX produced a truncated transcript (chunks hit the output-token
    // cap). Mark the whole job partial regardless of analyze status —
    // the analysis was performed against incomplete input, so even
    // a "success" on analyze rows is misleading.
    overall = "partial";
  } else if (analyzeRows.length === 0) {
    // Transcribe succeeded but no analyze rows — could be in flight,
    // or the client never called /relay/analyze (uses local model).
    overall = "success";
  } else if (analyzeSuccess.length === analyzeRows.length) {
    overall = "success";
  } else if (analyzeSuccess.length > 0) {
    overall = "partial";
  } else {
    overall = "failed";
  }

  const cost = rows.reduce((s, r) => s + (Number(r.cost_usd) || 0), 0);

  // Use `??` (nullish-coalesce) — NOT `||` — so a legitimate 0 isn't
  // treated as missing data. The test-run worker writes duration_ms=0
  // historically (pre-fix) on cache-hit siblings; even though the new
  // worker writes a non-zero shared wall-time, old audit rows from
  // earlier benchmark batches still live in the NDJSON and we want
  // those rendered correctly rather than collapsed to "—".
  const audioSec = tx?.audio_seconds ?? null;
  const audioBytes = tx?.audio_bytes ?? null;
  const txMs = tx?.duration_ms ?? null;
  const downloadMs = tx?.download_ms ?? null;
  // TX backend compute time = sum of per-chunk wall-times. Distinct
  // from txMs which is the outer parallel-fan-out wall-time.
  //   single-chunk: txMsSum ≈ txMs (one chunk, one duration)
  //   N-chunks at concurrency C: txMsSum ≈ N × per-chunk-duration
  //                              txMs    ≈ ⌈N/C⌉ × per-chunk-duration
  // Falls back to txMs (the wall-time) when chunk_durations_ms is
  // absent — old audit rows from before v0.2.41 don't have it.
  const chunkDurationsArr = Array.isArray(tx?.chunk_durations_ms) ? tx.chunk_durations_ms : null;
  const txMsSum = chunkDurationsArr
    ? chunkDurationsArr.reduce((s, d) => s + (Number(d) || 0), 0)
    : txMs;

  const audioMinutes = audioSec ? audioSec / 60 : null;
  const audioMb = audioBytes ? audioBytes / MB : null;

  // batch_id and source are stamped per audit row by the test-run
  // path; use the first non-null we see so dashboard filters work
  // regardless of which row gets read first in a multi-row job.
  const batchId = rows.find((r) => r.batch_id)?.batch_id || null;
  const source = rows.find((r) => r.source)?.source || null;

  return {
    job_id: key.startsWith("_orphan_") ? null : key,
    started_at: startedAt,
    completed_at: completedAt,
    install_id: tx?.install_id || rows[0].install_id || null,
    tier: tx?.tier || rows[0].tier || null,
    media_url: tx?.media_url || null,
    title: tx?.title || null,
    batch_id: batchId,
    source: source,
    audio_seconds: audioSec,
    audio_bytes: audioBytes,
    transcribe_status: txStatus,
    transcribe_backend: tx?.backend || null,
    transcribe_model: tx?.model || null,
    // transcribe_ms = outer wall-time of the whole TX phase (the
    // value the operator perceives as "how long did transcribe
    // take"). transcribe_ms_sum = total backend compute across all
    // chunks (drives cost; equals N × wall when N chunks run truly
    // sequentially, equals wall when single-chunk). For Gemini at
    // concurrency 12 over 3 chunks: wall ≈ 60s, sum ≈ 180s.
    transcribe_ms: txMs,
    transcribe_ms_sum: txMsSum,
    download_ms: downloadMs,
    chunk_count: tx?.chunk_count ?? null,
    analyze_windows_total: analyzeRows.length,
    analyze_windows_success: analyzeSuccess.length,
    analyze_windows_failed: analyzeFailed.length,
    analyze_backend: analyzeDominantBackend,
    analyze_model: analyzeDominantModel,
    // analyze_ms = SUM of per-window durations (total backend compute,
    // useful for cost). analyze_wall_time_ms = ELAPSED time from
    // first window start to last window end (the time a user actually
    // waits for the analyze phase). The two diverge when N windows
    // run in parallel: a 10-window 100s-per-window job has analyze_ms
    // = 1000s but analyze_wall_time_ms ≈ 100s (single batch) or
    // ≈ 200s (two sequential batches at concurrency 5).
    analyze_ms: analyzeMs,
    analyze_wall_time_ms: analyzeWallMs,
    overall_status: overall,
    wall_time_ms: completedAt - startedAt,
    cost_usd: cost,
    errors,
    // Derived rate metrics:
    transcribe_ms_per_min: audioMinutes && txMs ? txMs / audioMinutes : null,
    transcribe_ms_per_mb: audioMb && txMs ? txMs / audioMb : null,
    download_ms_per_mb: audioMb && downloadMs ? downloadMs / audioMb : null,
    analyze_ms_per_min: audioMinutes && analyzeMs ? analyzeMs / audioMinutes : null,
    analyze_wall_ms_per_min: audioMinutes && analyzeWallMs ? analyzeWallMs / audioMinutes : null,
    analyze_ms_per_mb: audioMb && analyzeMs ? analyzeMs / audioMb : null,
  };
}

// Pick the most frequent string in a list (ties broken by first
// occurrence). Used to attribute a backend/model to a job when its
// rows might disagree (e.g. some analyze windows hit gemini and
// fallback chain walked to hardware on others).
function dominant(values) {
  const counts = new Map();
  for (const v of values) {
    if (!v) continue;
    counts.set(v, (counts.get(v) || 0) + 1);
  }
  let best = null;
  let bestCount = 0;
  for (const [v, c] of counts) {
    if (c > bestCount) {
      best = v;
      bestCount = c;
    }
  }
  return best;
}

// Compute summary statistics across all aggregated jobs. Returned to
// the dashboard's top-of-page cards: success rate, total processing
// time, average wall-time per video, etc.
export function summarizeJobs(jobs) {
  const total = jobs.length;
  if (total === 0) {
    return {
      total: 0,
      success: 0,
      partial: 0,
      failed: 0,
      success_rate: 1,
      median_wall_time_ms: null,
      median_transcribe_ms_per_min: null,
      median_analyze_ms_per_min: null,
      total_cost_usd: 0,
      total_audio_hours: 0,
    };
  }
  const success = jobs.filter((j) => j.overall_status === "success").length;
  const partial = jobs.filter((j) => j.overall_status === "partial").length;
  const failed = jobs.filter((j) => j.overall_status === "failed").length;
  const totalCost = jobs.reduce((s, j) => s + (j.cost_usd || 0), 0);
  const totalAudioSec = jobs.reduce(
    (s, j) => s + (j.audio_seconds || 0),
    0
  );

  return {
    total,
    success,
    partial,
    failed,
    success_rate: (success + partial) / total,
    median_wall_time_ms: median(jobs.map((j) => j.wall_time_ms).filter(Number.isFinite)),
    median_transcribe_ms_per_min: median(
      jobs.map((j) => j.transcribe_ms_per_min).filter(Number.isFinite)
    ),
    median_analyze_ms_per_min: median(
      jobs.map((j) => j.analyze_ms_per_min).filter(Number.isFinite)
    ),
    total_cost_usd: totalCost,
    total_audio_hours: totalAudioSec / 3600,
  };
}

function median(arr) {
  if (!arr.length) return null;
  const sorted = [...arr].sort((a, b) => a - b);
  const mid = Math.floor(sorted.length / 2);
  return sorted.length % 2 === 0
    ? (sorted[mid - 1] + sorted[mid]) / 2
    : sorted[mid];
}