/**
 * Activity-label eval runner: replays the corpus against the production wire
 * shape (system = instruction variant, user = SDK-built prompt, max_tokens
 * 256 — matching the traced production requests) and reports per-variant
 * quality: format violations, first-word register distribution, cross-batch
 * redundancy, latency, and cost.
 *
 * Sequences run their steps serially; each generated label chains into the
 * next step's `previousLabels`. Variants with `usePreviousLabels` see that
 * context in the prompt; every variant is MEASURED against it, so blind and
 * continuity variants share one redundancy metric.
 *
 * Usage:
 *   node scripts/activity-labels/run.mts [--variants baseline,continuity]
 *     [--cases sandbox-probe-run,fib-rapid] [--samples 2] [--model id]
 *     [--concurrency 6] [--dry]
 */
import { join } from 'node:path';
import { fileURLToPath } from 'node:url';
import { existsSync, mkdirSync, readFileSync, writeFileSync } from 'node:fs';

import type { DryRunRecord, EvalCase, EvalRecord, RunArgs, RunRecord, Variant } from './types.mts';
import { aggregate, markdownReport } from './report.mts';
import { cases, stepEntries } from './corpus.mts';
import { renderStepPrompt } from './prompt.mts';
import { checkLabel } from './checks.mts';
import { variants } from './variants.mts';

const ROOT = fileURLToPath(new URL('../../', import.meta.url));
const RESULTS_DIR = fileURLToPath(new URL('./results', import.meta.url));
const CHAR_LIMIT = 600;
const MAX_TOKENS = 256;

interface AnthropicMessageResponse {
  content?: Array<{ text?: string }>;
  usage?: {
    input_tokens?: number;
    output_tokens?: number;
  };
}

interface RequestLabelOptions {
  apiKey: string;
  model: string;
  instruction: string;
  prompt: string;
}

type RequestLabelResult =
  | {
      label: string;
      latencyMs: number;
      inputTokens: number;
      outputTokens: number;
    }
  | {
      error: string;
      latencyMs: number;
    };

interface RunCaseOptions {
  apiKey: string;
  model: string;
  variant: Variant;
  sample: number;
  testCase: EvalCase;
  dry: boolean;
  records: RunRecord[];
}

type Task = () => Promise<void>;

function nextArgument(argv: readonly string[], index: number, key: string): string {
  const value = argv[index + 1];
  if (value == null || value.startsWith('--')) {
    throw new Error(`${key} requires a value`);
  }
  return value;
}

function positiveInteger(value: string, key: string): number {
  const parsed = Number(value);
  if (!Number.isInteger(parsed) || parsed <= 0) {
    throw new Error(`${key} must be a positive integer`);
  }
  return parsed;
}

function parseArgs(argv: readonly string[]): RunArgs {
  const args: RunArgs = {
    samples: 1,
    concurrency: 6,
    model: 'claude-haiku-4-5',
    dry: false,
  };
  for (let i = 0; i < argv.length; i++) {
    const key = argv[i];
    if (key === '--dry') {
      args.dry = true;
    } else if (key === '--variants') {
      args.variants = nextArgument(argv, i, key).split(',');
      i += 1;
    } else if (key === '--cases') {
      args.cases = nextArgument(argv, i, key).split(',');
      i += 1;
    } else if (key === '--samples') {
      args.samples = positiveInteger(nextArgument(argv, i, key), key);
      i += 1;
    } else if (key === '--model') {
      args.model = nextArgument(argv, i, key);
      i += 1;
    } else if (key === '--concurrency') {
      args.concurrency = positiveInteger(nextArgument(argv, i, key), key);
      i += 1;
    }
  }
  return args;
}

function loadKey(): string {
  if (process.env.ANTHROPIC_API_KEY) {
    return process.env.ANTHROPIC_API_KEY;
  }
  const envPath = join(ROOT, '.env');
  const line = existsSync(envPath)
    ? readFileSync(envPath, 'utf8')
        .split('\n')
        .find((entry) => entry.startsWith('ANTHROPIC_API_KEY='))
    : undefined;
  if (!line) {
    throw new Error(
      `ANTHROPIC_API_KEY not set and not found in ${envPath}.\n` +
        'Pass it inline:  ANTHROPIC_API_KEY=sk-… node scripts/activity-labels/run.mts',
    );
  }
  return line
    .slice('ANTHROPIC_API_KEY='.length)
    .trim()
    .replace(/^["']|["']$/g, '');
}

async function requestLabel({
  apiKey,
  model,
  instruction,
  prompt,
}: RequestLabelOptions): Promise<RequestLabelResult> {
  for (let attempt = 1; attempt <= 3; attempt++) {
    const started = Date.now();
    const response = await fetch('https://api.anthropic.com/v1/messages', {
      method: 'POST',
      headers: {
        'content-type': 'application/json',
        'x-api-key': apiKey,
        'anthropic-version': '2023-06-01',
      },
      body: JSON.stringify({
        model,
        max_tokens: MAX_TOKENS,
        system: instruction,
        messages: [{ role: 'user', content: prompt }],
      }),
    });
    if (response.ok) {
      const json = (await response.json()) as AnthropicMessageResponse;
      const label = (json.content ?? [])
        .map((block) => block.text ?? '')
        .join('')
        .trim()
        .replace(/^["']|["']$/g, '');
      return {
        label,
        latencyMs: Date.now() - started,
        inputTokens: json.usage?.input_tokens ?? 0,
        outputTokens: json.usage?.output_tokens ?? 0,
      };
    }
    const body = await response.text();
    if (attempt < 3 && [429, 500, 529].includes(response.status)) {
      const retryAfter = Number(response.headers.get('retry-after'));
      const waitMs =
        Number.isFinite(retryAfter) && retryAfter > 0 ? retryAfter * 1000 : attempt * 2000;
      await new Promise((resolve) => setTimeout(resolve, Math.min(waitMs, 15000)));
      continue;
    }
    return {
      error: `HTTP ${response.status}: ${body.slice(0, 160)}`,
      latencyMs: Date.now() - started,
    };
  }
  throw new Error('label request exhausted retries without a result');
}

/** One case chain: steps serial, labels feeding forward. */
async function runCase({
  apiKey,
  model,
  variant,
  sample,
  testCase,
  dry,
  records,
}: RunCaseOptions): Promise<void> {
  const chain: string[] = [];
  for (const step of testCase.steps) {
    const prompt = renderStepPrompt(step, {
      charLimit: CHAR_LIMIT,
      previousLabels: variant.usePreviousLabels ? chain : null,
      previousLabelCap: variant.previousLabelCap,
    });
    const stepId = step.id ?? testCase.id;
    if (dry) {
      records.push({ variant: variant.name, sample, caseId: testCase.id, stepId, prompt });
      continue;
    }
    const result = await requestLabel({ apiKey, model, instruction: variant.instruction, prompt });
    if ('error' in result) {
      records.push({
        variant: variant.name,
        sample,
        caseId: testCase.id,
        stepId,
        error: result.error,
      });
      continue;
    }
    const { flags, wordCount, firstWord } = checkLabel(result.label, {
      entries: stepEntries(step),
      previousLabels: chain,
    });
    chain.push(result.label);
    records.push({
      variant: variant.name,
      sample,
      caseId: testCase.id,
      stepId,
      label: result.label,
      production: step.productionLabel,
      flags,
      wordCount,
      firstWord,
      latencyMs: result.latencyMs,
      inputTokens: result.inputTokens,
      outputTokens: result.outputTokens,
    });
  }
}

async function pool(tasks: readonly Task[], size: number): Promise<void> {
  const queue = [...tasks];
  const workers = Array.from({ length: Math.min(size, queue.length) }, async () => {
    while (queue.length > 0) {
      const task = queue.shift();
      if (task != null) {
        await task();
      }
    }
  });
  await Promise.all(workers);
}

function isDryRunRecord(record: RunRecord): record is DryRunRecord {
  return 'prompt' in record;
}

function isEvalRecord(record: RunRecord): record is EvalRecord {
  return !isDryRunRecord(record);
}

async function main(): Promise<void> {
  const args = parseArgs(process.argv.slice(2));
  const selectedVariants = args.variants;
  const selectedCases = args.cases;
  const runVariants = selectedVariants
    ? variants.filter((variant) => selectedVariants.includes(variant.name))
    : variants;
  const runCases = selectedCases
    ? cases.filter((testCase) => selectedCases.includes(testCase.id))
    : cases;
  if (runVariants.length === 0 || runCases.length === 0) {
    throw new Error('nothing selected — check --variants / --cases names');
  }
  const apiKey = args.dry ? '' : loadKey();
  const records: RunRecord[] = [];
  const tasks: Task[] = [];
  for (const variant of runVariants) {
    for (let sample = 1; sample <= args.samples; sample++) {
      for (const testCase of runCases) {
        tasks.push(() =>
          runCase({ apiKey, model: args.model, variant, sample, testCase, dry: args.dry, records }),
        );
      }
    }
  }
  const totalSteps = runCases.reduce((sum, c) => sum + c.steps.length, 0);
  console.log(
    `${args.dry ? 'DRY RUN — rendering only' : `model ${args.model}`} · ${runVariants.length} variants × ${args.samples} samples × ${runCases.length} cases (${totalSteps} steps each pass)`,
  );
  const started = Date.now();
  await pool(tasks, args.concurrency);
  console.log(`done in ${((Date.now() - started) / 1000).toFixed(1)}s\n`);

  if (args.dry) {
    const dryRecords = records.filter(isDryRunRecord);
    for (const record of dryRecords.slice(0, 3)) {
      console.log(`--- ${record.variant} / ${record.caseId} / ${record.stepId} ---`);
      console.log(record.prompt);
      console.log('');
    }
    console.log(`rendered ${dryRecords.length} prompts (showing 3)`);
    return;
  }

  const evalRecords = records.filter(isEvalRecord);
  const aggregates = aggregate(evalRecords, args.model);
  const variantNames = runVariants.map((variant) => variant.name);
  const report = markdownReport({
    records: evalRecords,
    aggregates,
    runCases,
    variantNames,
    model: args.model,
    samples: args.samples,
  });
  mkdirSync(RESULTS_DIR, { recursive: true });
  const stamp = new Date().toISOString().replace(/[:.]/g, '-');
  writeFileSync(
    join(RESULTS_DIR, `${stamp}.json`),
    JSON.stringify({ args, records: evalRecords }, null, 2),
  );
  writeFileSync(join(RESULTS_DIR, 'latest.md'), report);

  console.log(report.split('## Per-case')[0]);
  console.log(`full per-case tables: scripts/activity-labels/results/latest.md`);
}

main().catch((error: Error) => {
  console.error('ERR', error.message);
  process.exit(1);
});