import express from "express";
import { fileURLToPath } from "url";
import { dirname, join } from "path";

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

const app = express();
const PORT = process.env.PORT || 7860;

const WFM_BASE = "https://api.warframe.market/v2";
const WFM_HEADERS = { Platform: "pc", Language: "en" };

// --- Rate limiter: token bucket, 5 tokens/sec burst-friendly ---
class RateLimiter {
  constructor(maxPerSecond = 5) {
    this.maxPerSecond = maxPerSecond;
    this.tokens = maxPerSecond;
    this.lastRefill = Date.now();
  }

  async acquire() {
    const now = Date.now();
    const elapsed = now - this.lastRefill;
    if (elapsed >= 1000) {
      this.tokens = Math.min(this.maxPerSecond, this.tokens + Math.floor(elapsed / 1000) * this.maxPerSecond);
      this.lastRefill = now;
    }
    if (this.tokens <= 0) {
      const wait = 1000 - elapsed;
      await new Promise((r) => setTimeout(r, wait));
      this.tokens = this.maxPerSecond;
      this.lastRefill = Date.now();
    }
    this.tokens--;
  }
}

const limiter = new RateLimiter(15);

// --- In-memory cache ---
class Cache {
  constructor(ttlMs) {
    this.ttlMs = ttlMs;
    this.store = new Map();
  }

  get(key) {
    const entry = this.store.get(key);
    if (!entry) return null;
    if (Date.now() - entry.ts > this.ttlMs) {
      this.store.delete(key);
      return null;
    }
    return entry.data;
  }

  set(key, data) {
    this.store.set(key, { data, ts: Date.now() });
  }

  invalidate(key) {
    this.store.delete(key);
  }

  clear() {
    this.store.clear();
  }
}

const catalogCache = new Cache(60 * 60 * 1000); // 1 hour
const ordersCache = new Cache(60 * 1000); // 60s
const priceCache = new Cache(60 * 1000); // 60s for batch price lookups

// --- Upstream fetch with rate limiting ---
async function wfmFetch(path) {
  await limiter.acquire();
  const res = await fetch(`${WFM_BASE}${path}`, { headers: WFM_HEADERS });
  if (!res.ok) {
    const text = await res.text();
    throw new Error(`WFM API ${res.status}: ${text}`);
  }
  return res.json();
}

// --- API routes ---
app.get("/api/items", async (req, res) => {
  try {
    let items = catalogCache.get("catalog");
    if (!items) {
      const body = await wfmFetch("/items");
      items = body.data;
      catalogCache.set("catalog", items);
    }
    res.json(items);
  } catch (err) {
    console.error("Error fetching items:", err.message);
    res.status(502).json({ error: "Failed to fetch item catalog from Warframe Market" });
  }
});

app.get("/api/refresh-catalog", async (req, res) => {
  try {
    catalogCache.clear();
    const body = await wfmFetch("/items");
    catalogCache.set("catalog", body.data);
    res.json({ ok: true, count: body.data.length });
  } catch (err) {
    console.error("Error refreshing catalog:", err.message);
    res.status(502).json({ error: "Failed to refresh catalog" });
  }
});

app.get("/api/orders/:slug", async (req, res) => {
  const { slug } = req.params;
  try {
    let orders = ordersCache.get(slug);
    if (!orders) {
      const body = await wfmFetch(`/orders/item/${encodeURIComponent(slug)}`);
      orders = body.data;
      ordersCache.set(slug, orders);
    }
    res.json(orders);
  } catch (err) {
    console.error(`Error fetching orders for ${slug}:`, err.message);
    res.status(502).json({ error: `Failed to fetch orders for ${slug}` });
  }
});

// --- Batch price lookup ---
app.use(express.json());
app.post("/api/prices", async (req, res) => {
  const { slugs } = req.body;
  if (!Array.isArray(slugs) || slugs.length === 0) {
    return res.status(400).json({ error: "slugs array required" });
  }

  const result = {};
  const toFetch = [];

  for (const slug of slugs) {
    const cached = priceCache.get(slug);
    if (cached !== null) {
      result[slug] = cached;
    } else {
      toFetch.push(slug);
    }
  }

  // Build a slug→tags lookup from catalog cache (ensure it's loaded)
  let catalog = catalogCache.get("catalog");
  if (!catalog) {
    try {
      const body = await wfmFetch("/items");
      catalog = body.data;
      catalogCache.set("catalog", catalog);
    } catch {
      catalog = [];
    }
  }
  const slugTags = {};
  for (const item of catalog) {
    slugTags[item.slug] = item.tags || [];
  }

  // Fetch missing prices in parallel batches
  const CONCURRENCY = 15;
  for (let i = 0; i < toFetch.length; i += CONCURRENCY) {
    const batch = toFetch.slice(i, i + CONCURRENCY);
    const results = await Promise.allSettled(
      batch.map(async (slug) => {
        const tags = slugTags[slug] || [];
        const isRanked = tags.includes("arcane_enhancement") || tags.includes("mod");

        if (isRanked) {
          // For arcanes/mods, fetch all orders and filter to max-rank only
          const body = await wfmFetch(`/orders/item/${encodeURIComponent(slug)}`);
          const orders = body.data;
          const online = (orders || []).filter(
            (o) => o.user?.status === "ingame" || o.user?.status === "online"
          );
          const maxRank = online.length > 0
            ? Math.max(...online.map((o) => o.rank ?? 0))
            : 0;
          const maxedOnline = online.filter((o) => (o.rank ?? 0) === maxRank);
          const sells = maxedOnline.filter((o) => o.type === "sell");
          const buys = maxedOnline.filter((o) => o.type === "buy");
          const lowestSell = sells.length > 0 ? Math.min(...sells.map((o) => o.platinum)) : null;
          const highestBuy = buys.length > 0 ? Math.max(...buys.map((o) => o.platinum)) : null;
          return { slug, lowestSell, highestBuy, activeSells: sells.length };
        }

        // Normal items: use the lightweight /top endpoint
        const body = await wfmFetch(`/orders/item/${encodeURIComponent(slug)}/top`);
        const data = body.data;
        const sells = (data.sell || [])
          .filter((o) => o.user?.status === "ingame" || o.user?.status === "online");
        const buys = (data.buy || [])
          .filter((o) => o.user?.status === "ingame" || o.user?.status === "online");
        const lowestSell = sells.length > 0 ? Math.min(...sells.map((o) => o.platinum)) : null;
        const highestBuy = buys.length > 0 ? Math.max(...buys.map((o) => o.platinum)) : null;
        return { slug, lowestSell, highestBuy, activeSells: sells.length };
      })
    );
    for (const r of results) {
      if (r.status === "fulfilled") {
        const { slug, ...prices } = r.value;
        result[slug] = prices;
        priceCache.set(slug, prices);
      }
    }
  }

  res.json(result);
});

// --- SSE batch price streaming ---
app.post("/api/prices/stream", async (req, res) => {
  const { slugs } = req.body;
  if (!Array.isArray(slugs) || slugs.length === 0) {
    return res.status(400).json({ error: "slugs array required" });
  }

  res.setHeader("Content-Type", "text/event-stream");
  res.setHeader("Cache-Control", "no-cache");
  res.setHeader("Connection", "keep-alive");
  res.flushHeaders();

  const toFetch = [];
  const cached = {};
  for (const slug of slugs) {
    const c = priceCache.get(slug);
    if (c !== null) {
      cached[slug] = c;
    } else {
      toFetch.push(slug);
    }
  }

  // Send cached results immediately
  if (Object.keys(cached).length > 0) {
    res.write(`data: ${JSON.stringify(cached)}\n\n`);
  }

  // Ensure catalog is loaded
  let catalog = catalogCache.get("catalog");
  if (!catalog) {
    try {
      const body = await wfmFetch("/items");
      catalog = body.data;
      catalogCache.set("catalog", catalog);
    } catch {
      catalog = [];
    }
  }
  const slugTags = {};
  for (const item of catalog) {
    slugTags[item.slug] = item.tags || [];
  }

  // Stream results — fetch in parallel batches with retry for failures
  const CONCURRENCY = 10;
  const heartbeat = setInterval(() => res.write(": heartbeat\n\n"), 15000);

  async function fetchSlug(slug) {
    const tags = slugTags[slug] || [];
    const isRanked = tags.includes("arcane_enhancement") || tags.includes("mod");

    for (let attempt = 0; attempt < 3; attempt++) {
      try {
        if (isRanked) {
          const body = await wfmFetch(`/orders/item/${encodeURIComponent(slug)}`);
          const orders = body.data;
          const online = (orders || []).filter(
            (o) => o.user?.status === "ingame" || o.user?.status === "online"
          );
          const maxRank = online.length > 0
            ? Math.max(...online.map((o) => o.rank ?? 0))
            : 0;
          const maxedOnline = online.filter((o) => (o.rank ?? 0) === maxRank);
          const sells = maxedOnline.filter((o) => o.type === "sell");
          const buys = maxedOnline.filter((o) => o.type === "buy");
          const lowestSell = sells.length > 0 ? Math.min(...sells.map((o) => o.platinum)) : null;
          const highestBuy = buys.length > 0 ? Math.max(...buys.map((o) => o.platinum)) : null;
          return { slug, lowestSell, highestBuy, activeSells: sells.length };
        }

        const body = await wfmFetch(`/orders/item/${encodeURIComponent(slug)}/top`);
        const data = body.data;
        const sells = (data.sell || [])
          .filter((o) => o.user?.status === "ingame" || o.user?.status === "online");
        const buys = (data.buy || [])
          .filter((o) => o.user?.status === "ingame" || o.user?.status === "online");
        const lowestSell = sells.length > 0 ? Math.min(...sells.map((o) => o.platinum)) : null;
        const highestBuy = buys.length > 0 ? Math.max(...buys.map((o) => o.platinum)) : null;
        return { slug, lowestSell, highestBuy, activeSells: sells.length };
      } catch {
        if (attempt < 2) await new Promise((r) => setTimeout(r, 500 * (attempt + 1)));
      }
    }
    return null; // failed after 3 attempts
  }

  const failedSlugs = [];
  for (let i = 0; i < toFetch.length; i += CONCURRENCY) {
    const batch = toFetch.slice(i, i + CONCURRENCY);
    const results = await Promise.all(batch.map((slug) => fetchSlug(slug)));

    const batchResult = {};
    for (const r of results) {
      if (r) {
        const { slug, ...prices } = r;
        batchResult[slug] = prices;
        priceCache.set(slug, prices);
      }
    }
    // Track failed slugs for a final retry pass
    for (let j = 0; j < results.length; j++) {
      if (!results[j]) failedSlugs.push(batch[j]);
    }
    if (Object.keys(batchResult).length > 0) {
      res.write(`data: ${JSON.stringify(batchResult)}\n\n`);
    }
  }

  // Final retry pass for any items that failed
  if (failedSlugs.length > 0) {
    const retryResult = {};
    for (const slug of failedSlugs) {
      const r = await fetchSlug(slug);
      if (r) {
        const { slug: s, ...prices } = r;
        retryResult[s] = prices;
        priceCache.set(s, prices);
      }
    }
    if (Object.keys(retryResult).length > 0) {
      res.write(`data: ${JSON.stringify(retryResult)}\n\n`);
    }
  }

  clearInterval(heartbeat);
  res.write("event: done\ndata: {}\n\n");
  res.end();
});

// --- Serve static React build ---
const clientDist = join(__dirname, "..", "client", "dist");
app.use(express.static(clientDist));

// SPA fallback
app.get("*", (req, res) => {
  res.sendFile(join(clientDist, "index.html"));
});

app.listen(PORT, "0.0.0.0", () => {
  console.log(`WFM Tracker server listening on port ${PORT}`);
});