/**
 * Environment variables used by this file
 * Chatter integration
 * - CHATTER_API_CONCURRENCY
 *   - Maximum number of jobs/interactions posted concurrently *per shop* (within a single shop's batch).
 *   - Default: 5
 *   - Used by: createConcurrencyLimit(MAX_CONCURRENCY)
 *
 * - CHATTER_API_REQUESTS_PER_SECOND
 *   - Per-company outbound request rate (token bucket refill rate).
 *   - Default: 3
 *   - Must be a positive number; otherwise falls back to default.
 *   - Used by: createTokenBucketRateLimiter({ refillPerSecond })
 *
 * - CHATTER_API_BURST_CAPACITY
 *   - Per-company token bucket capacity (maximum burst size).
 *   - Default: equals CHATTER_API_REQUESTS_PER_SECOND (i.e., 3 unless overridden)
 *   - Must be a positive number; otherwise falls back to default.
 *   - Used by: createTokenBucketRateLimiter({ capacity })
 *
 * - CHATTER_API_MAX_RETRIES
 *   - Maximum number of attempts for posting an interaction before giving up.
 *   - Default: 6
 *   - Must be a positive integer; otherwise falls back to default.
 *   - Used by: postInteractionWithPolicy()
 *
 * - CHATTER_API_TOKEN
 *   - Optional override token for emergency/dev scenarios.
 *   - If set, bypasses Secrets Manager/Redis token retrieval and uses this value for all companies.
 *   - Used by: getChatterApiTokenCached()
 *
 * Notes
 * - Per-company API tokens are otherwise fetched via getChatterApiToken(companyId) (Secrets Manager)
 *   and may be cached via `sessionUtils.getChatterToken/setChatterToken` (Redis-backed).
 */

const queries = require("../graphql-client/queries");
const moment = require("moment-timezone");
const logger = require("../utils/logger");
const { ChatterApiClient, getChatterApiToken, CHATTER_BASE_URL } = require("../chatter/chatter-client");

const client = require("../graphql-client/graphql-client").client;

const CHATTER_EVENT = process.env.NODE_ENV === "production" ? "delivery" : "TEST_INTEGRATION";
const MAX_CONCURRENCY = Number(process.env.CHATTER_API_CONCURRENCY || 5);
const CHATTER_REQUESTS_PER_SECOND = getPositiveNumber(process.env.CHATTER_API_REQUESTS_PER_SECOND, 3);
const CHATTER_BURST_CAPACITY = getPositiveNumber(process.env.CHATTER_API_BURST_CAPACITY, CHATTER_REQUESTS_PER_SECOND);
const CHATTER_MAX_RETRIES = getPositiveInteger(process.env.CHATTER_API_MAX_RETRIES, 6);

// Client caching (in-memory) - tokens are now cached in Redis
const clientCache = new Map(); // companyId -> ChatterApiClient
const tokenInFlight = new Map(); // companyId -> Promise<string> (for in-flight deduplication)
const companyRateLimiters = new Map(); // companyId -> rate limiter

/**
 * Core processing function for Chatter API jobs.
 * This can be called by the HTTP handler or the BullMQ worker.
 *
 * @param {Object} options - Processing options
 * @param {string} options.start - Start date for the delivery window
 * @param {string} options.end - End date for the delivery window
 * @param {Array<string>} options.bodyshopIds - Optional specific shops to process
 * @param {boolean} options.skipUpload - Dry-run flag
 * @param {Object} options.sessionUtils - Optional session utils for token caching
 * @returns {Promise<Object>} Result with totals, allShopSummaries, and allErrors
 */
async function processChatterApiJob({ start, end, bodyshopIds, skipUpload, sessionUtils }) {
  logger.log("chatter-api-start", "DEBUG", "api", null, null);

  const allErrors = [];
  const allShopSummaries = [];

  // Shops that DO have chatter_company_id
  const { bodyshops } = await client.request(queries.GET_CHATTER_SHOPS_WITH_COMPANY);

  const shopsToProcess =
    bodyshopIds?.length > 0 ? bodyshops.filter((shop) => bodyshopIds.includes(shop.id)) : bodyshops;

  logger.log("chatter-api-shopsToProcess-generated", "DEBUG", "api", null, { count: shopsToProcess.length });

  if (shopsToProcess.length === 0) {
    logger.log("chatter-api-shopsToProcess-empty", "DEBUG", "api", null, null);
    return {
      totals: { shops: 0, jobs: 0, sent: 0, duplicates: 0, failed: 0 },
      allShopSummaries: [],
      allErrors: []
    };
  }

  await processBatchApi({
    shopsToProcess,
    start,
    end,
    skipUpload,
    allShopSummaries,
    allErrors,
    sessionUtils
  });

  const totals = allShopSummaries.reduce(
    (acc, s) => {
      acc.shops += 1;
      acc.jobs += s.jobs || 0;
      acc.sent += s.sent || 0;
      acc.duplicates += s.duplicates || 0;
      acc.failed += s.failed || 0;
      return acc;
    },
    { shops: 0, jobs: 0, sent: 0, duplicates: 0, failed: 0 }
  );

  logger.log("chatter-api-end", "DEBUG", "api", null, totals);

  return { totals, allShopSummaries, allErrors };
}

exports.default = async (req, res) => {
  if (process.env.NODE_ENV !== "production") return res.sendStatus(403);
  if (req.headers["x-imex-auth"] !== process.env.AUTOHOUSE_AUTH_TOKEN) return res.sendStatus(401);

  res.status(202).json({
    success: true,
    message: "Chatter API job queued for processing",
    timestamp: new Date().toISOString()
  });

  try {
    const { dispatchChatterApiJob } = require("./queues/chatterApiQueue");
    const { start, end, bodyshopIds, skipUpload } = req.body;

    await dispatchChatterApiJob({
      start,
      end,
      bodyshopIds,
      skipUpload
    });
  } catch (error) {
    logger.log("chatter-api-queue-dispatch-error", "ERROR", "api", null, {
      error: error.message,
      stack: error.stack
    });
  }
};

exports.processChatterApiJob = processChatterApiJob;

async function processBatchApi({ shopsToProcess, start, end, skipUpload, allShopSummaries, allErrors, sessionUtils }) {
  for (const bodyshop of shopsToProcess) {
    const summary = {
      bodyshopid: bodyshop.id,
      imexshopid: bodyshop.imexshopid,
      shopname: bodyshop.shopname,
      chatter_company_id: bodyshop.chatter_company_id,
      chatterid: bodyshop.chatterid,
      jobs: 0,
      sent: 0,
      duplicates: 0,
      failed: 0,
      ok: true
    };

    try {
      logger.log("chatter-api-start-shop", "DEBUG", "api", bodyshop.id, { shopname: bodyshop.shopname });

      const companyId = parseCompanyId(bodyshop.chatter_company_id);
      if (!companyId) {
        summary.ok = false;
        summary.failed = 0;
        allErrors.push({
          ...pickShop(bodyshop),
          fatal: true,
          errors: [`Invalid chatter_company_id: "${bodyshop.chatter_company_id}"`]
        });
        allShopSummaries.push(summary);
        continue;
      }

      const chatterApi = await getChatterApiClient(companyId, sessionUtils);

      const { jobs } = await client.request(queries.CHATTER_QUERY, {
        bodyshopid: bodyshop.id,
        start: start ? moment(start).startOf("day") : moment().subtract(1, "days").startOf("day"),
        ...(end && { end: moment(end).endOf("day") })
      });

      summary.jobs = jobs.length;

      // concurrency-limited posting
      const limit = createConcurrencyLimit(MAX_CONCURRENCY);
      const results = await Promise.all(
        jobs.map((j) =>
          limit(async () => {
            const payload = buildInteractionPayload(bodyshop, j);

            // keep legacy flag name: skipUpload == dry-run
            if (skipUpload) return { ok: true, dryRun: true };

            const r = await postInteractionWithPolicy(chatterApi, companyId, payload);
            return r;
          })
        )
      );

      for (const r of results) {
        if (r?.dryRun) continue;
        if (r?.ok && r?.duplicate) summary.duplicates += 1;
        else if (r?.ok) summary.sent += 1;
        else summary.failed += 1;
      }

      // record failures with some detail (cap to avoid huge emails)
      const failures = results
        .filter((r) => r && r.ok === false)
        .slice(0, 25)
        .map((r) => ({
          status: r.status,
          error: r.error,
          context: r.context
        }));

      if (failures.length) {
        summary.ok = false;
        allErrors.push({
          ...pickShop(bodyshop),
          fatal: false,
          errors: failures
        });
      }

      logger.log("chatter-api-end-shop", "DEBUG", "api", bodyshop.id, summary);
    } catch (error) {
      summary.ok = false;

      logger.log("chatter-api-error-shop", "ERROR", "api", bodyshop.id, {
        error: error.message,
        stack: error.stack
      });

      allErrors.push({
        ...pickShop(bodyshop),
        fatal: true,
        errors: [error.toString()]
      });
    } finally {
      allShopSummaries.push(summary);
    }
  }
}

function buildInteractionPayload(bodyshop, j) {
  const isCompany = Boolean(j.ownr_co_nm);

  const locationIdentifier = `${bodyshop.chatter_company_id}-${bodyshop.id}`;
  const timestamp = formatChatterTimestamp(j.actual_delivery, bodyshop.timezone);

  if (j.actual_delivery && !timestamp) {
    logger.log("chatter-api-invalid-delivery-timestamp", "WARN", "api", bodyshop.id, {
      bodyshopId: bodyshop.id,
      jobId: j.id,
      timezone: bodyshop.timezone,
      actualDelivery: j.actual_delivery
    });
  }

  return {
    locationIdentifier: locationIdentifier,
    event: CHATTER_EVENT,
    consent: "true",
    transactionId: j.ro_number != null ? String(j.ro_number) : undefined,
    timestamp,
    firstName: isCompany ? null : j.ownr_fn || null,
    lastName: isCompany ? j.ownr_co_nm : j.ownr_ln || null,
    emailAddress: j.ownr_ea || undefined,
    phoneNumber: j.ownr_ph1 || undefined,
    metadata: {
      imexShopId: bodyshop.imexshopid,
      bodyshopId: bodyshop.id,
      jobId: j.id
    }
  };
}

async function postInteractionWithPolicy(chatterApi, companyId, payload) {
  const limiter = getCompanyRateLimiter(companyId);
  const requestContext = {
    companyId,
    locationIdentifier: payload?.locationIdentifier,
    transactionId: payload?.transactionId,
    timestamp: payload?.timestamp ?? null,
    bodyshopId: payload?.metadata?.bodyshopId ?? null,
    jobId: payload?.metadata?.jobId ?? null
  };

  for (let attempt = 0; attempt < CHATTER_MAX_RETRIES; attempt++) {
    await limiter.acquire();

    try {
      await chatterApi.postInteraction(companyId, payload);
      return { ok: true };
    } catch (e) {
      // duplicate -> treat as successful idempotency outcome
      if (e.status === 409) return { ok: true, duplicate: true, error: e.data };

      // rate limited -> backoff + retry
      if (e.status === 429) {
        const retryDelayMs = retryDelayMsForError(e, attempt);
        limiter.pause(retryDelayMs);
        logger.log("chatter-api-request-rate-limited", "WARN", "api", requestContext.bodyshopId, {
          ...requestContext,
          attempt: attempt + 1,
          maxAttempts: CHATTER_MAX_RETRIES,
          status: e.status,
          retryAfterMs: e.retryAfterMs,
          retryDelayMs,
          error: e.data ?? e.message
        });
        await sleep(retryDelayMs);
        continue;
      }

      logger.log("chatter-api-request-failed", "ERROR", "api", requestContext.bodyshopId, {
        ...requestContext,
        attempt: attempt + 1,
        maxAttempts: CHATTER_MAX_RETRIES,
        status: e.status,
        error: e.data ?? e.message
      });
      return { ok: false, status: e.status, error: e.data ?? e.message, context: requestContext };
    }
  }

  logger.log("chatter-api-request-failed", "ERROR", "api", requestContext.bodyshopId, {
    ...requestContext,
    maxAttempts: CHATTER_MAX_RETRIES,
    status: 429,
    error: "rate limit retry exhausted"
  });

  return { ok: false, status: 429, error: "rate limit retry exhausted", context: requestContext };
}

function parseCompanyId(val) {
  const s = String(val ?? "").trim();
  if (!s) return null;
  const n = Number(s);
  if (!Number.isFinite(n) || !Number.isInteger(n) || n <= 0) return null;
  return n;
}

function pickShop(bodyshop) {
  return {
    bodyshopid: bodyshop.id,
    imexshopid: bodyshop.imexshopid,
    shopname: bodyshop.shopname,
    chatter_company_id: bodyshop.chatter_company_id,
    chatterid: bodyshop.chatterid
  };
}

function sleep(ms) {
  return new Promise((r) => setTimeout(r, ms));
}

function backoffMs(attempt) {
  const base = Math.min(30_000, 500 * 2 ** attempt);
  const jitter = Math.floor(Math.random() * 250);
  return base + jitter;
}

function retryDelayMsForError(error, attempt) {
  const retryAfterMs = Number(error?.retryAfterMs);
  if (Number.isFinite(retryAfterMs) && retryAfterMs > 0) {
    const jitter = Math.floor(Math.random() * 250);
    return Math.min(60_000, retryAfterMs + jitter);
  }
  return backoffMs(attempt);
}

function formatChatterTimestamp(value, timezone) {
  if (!value) return undefined;

  const hasValidTimezone = Boolean(timezone && moment.tz.zone(timezone));
  const parsed = hasValidTimezone ? moment(value).tz(timezone) : moment(value);
  if (!parsed.isValid()) return undefined;

  // Keep a strict, Chatter-friendly timestamp without fractional seconds.
  return parsed.utc().format("YYYY-MM-DD HH:mm:ss[Z]");
}

function createConcurrencyLimit(max) {
  let active = 0;
  const queue = [];

  const next = () => {
    if (active >= max) return;
    const fn = queue.shift();
    if (!fn) return;
    active++;
    fn()
      .catch(() => {})
      .finally(() => {
        active--;
        next();
      });
  };

  return (fn) =>
    new Promise((resolve, reject) => {
      queue.push(async () => {
        try {
          resolve(await fn());
        } catch (e) {
          reject(e);
        }
      });
      next();
    });
}

function getCompanyRateLimiter(companyId) {
  const key = String(companyId);
  const existing = companyRateLimiters.get(key);
  if (existing) return existing;

  const limiter = createTokenBucketRateLimiter({
    refillPerSecond: CHATTER_REQUESTS_PER_SECOND,
    capacity: CHATTER_BURST_CAPACITY
  });

  companyRateLimiters.set(key, limiter);
  return limiter;
}

function createTokenBucketRateLimiter({ refillPerSecond, capacity }) {
  let tokens = capacity;
  let lastRefillAt = Date.now();
  let pauseUntil = 0;
  let chain = Promise.resolve();

  const refill = () => {
    const now = Date.now();
    const elapsedSec = (now - lastRefillAt) / 1000;
    if (elapsedSec <= 0) return;
    tokens = Math.min(capacity, tokens + elapsedSec * refillPerSecond);
    lastRefillAt = now;
  };

  const waitForPermit = async () => {
    for (;;) {
      const now = Date.now();
      if (pauseUntil > now) {
        await sleep(pauseUntil - now);
        continue;
      }

      refill();
      if (tokens >= 1) {
        tokens -= 1;
        return;
      }

      const missing = 1 - tokens;
      const waitMs = Math.max(25, Math.ceil((missing / refillPerSecond) * 1000));
      await sleep(waitMs);
    }
  };

  return {
    acquire() {
      chain = chain.then(waitForPermit, waitForPermit);
      return chain;
    },
    pause(ms) {
      const n = Number(ms);
      if (!Number.isFinite(n) || n <= 0) return;
      pauseUntil = Math.max(pauseUntil, Date.now() + n);
    }
  };
}

function getPositiveNumber(value, fallback) {
  const n = Number(value);
  return Number.isFinite(n) && n > 0 ? n : fallback;
}

function getPositiveInteger(value, fallback) {
  const n = Number(value);
  return Number.isInteger(n) && n > 0 ? n : fallback;
}

/**
 * Returns a per-company Chatter API client, caching both the token and the client.
 */
async function getChatterApiClient(companyId, sessionUtils) {
  const key = String(companyId);

  const existing = clientCache.get(key);
  if (existing) return existing;

  const apiToken = await getChatterApiTokenCached(companyId, sessionUtils);
  const chatterApi = new ChatterApiClient({ baseUrl: CHATTER_BASE_URL, apiToken });

  clientCache.set(key, chatterApi);
  return chatterApi;
}

/**
 * Fetches the per-company token from AWS Secrets Manager with Redis caching
 * SecretId: CHATTER_COMPANY_KEY_<companyId>
 *
 * Uses Redis caching + in-flight dedupe to avoid hammering Secrets Manager.
 */
async function getChatterApiTokenCached(companyId, sessionUtils) {
  const key = String(companyId ?? "").trim();
  if (!key) throw new Error("getChatterApiToken: companyId is required");

  // Optional override for emergency/dev
  if (process.env.CHATTER_API_TOKEN) return process.env.CHATTER_API_TOKEN;

  // Check Redis cache if sessionUtils is available
  if (sessionUtils?.getChatterToken) {
    const cachedToken = await sessionUtils.getChatterToken(key);
    if (cachedToken) {
      logger.log("chatter-api-get-token-cache-hit", "DEBUG", "api", null, { companyId: key });
      return cachedToken;
    }
  }

  // Check for in-flight requests
  const inflight = tokenInFlight.get(key);
  if (inflight) return inflight;

  const p = (async () => {
    logger.log("chatter-api-get-token-cache-miss", "DEBUG", "api", null, { companyId: key });

    // Fetch token from Secrets Manager using shared function
    const token = await getChatterApiToken(companyId);

    // Store in Redis cache if sessionUtils is available
    if (sessionUtils?.setChatterToken) {
      await sessionUtils.setChatterToken(key, token);
    }

    return token;
  })();

  tokenInFlight.set(key, p);

  try {
    return await p;
  } finally {
    tokenInFlight.delete(key);
  }
}