import { Router } from "express";
import { ASSET_ID_RE, db, nextId } from "../db.js";

export const inventoryRouter: Router = Router();

type CreateBody = {
  assetId: string;
  productId: string;
  shopId?: string | null;
  binId?: string | null;
  price: number;
  thc?: number;
  cbd?: number;
  totalCannabinoids?: number;
  weight?: number;
  countOriginal?: number;
  unitWeight?: number;
  purchaseDate: string;
};

inventoryRouter.post("/inventory", (req, res) => {
  const body = req.body as CreateBody;
  if (!body.productId) return res.status(400).json({ error: "productId required" });
  if (!body.purchaseDate) return res.status(400).json({ error: "purchaseDate required" });
  if (!Number.isFinite(body.price) || body.price < 0) {
    return res.status(400).json({ error: "price required" });
  }
  const assetId = (body.assetId ?? "").trim();
  if (!ASSET_ID_RE.test(assetId)) {
    return res.status(400).json({ error: "assetId must be exactly 6 digits" });
  }
  const taken = db
    .prepare<[string], { id: string }>(
      `SELECT id FROM inventory_items WHERE asset_id = ?`,
    )
    .get(assetId);
  if (taken) {
    return res.status(409).json({ error: "asset id already in use", id: taken.id });
  }

  const product = db
    .prepare<[string], { id: string; kind: string }>(
      `SELECT id, kind FROM products WHERE id = ?`,
    )
    .get(body.productId);
  if (!product) return res.status(404).json({ error: "product not found" });

  const isDiscrete = product.kind === "discrete";
  const id = nextId("inv", "inventory_items");

  db.prepare(
    `INSERT INTO inventory_items (
       id, asset_id, product_id,
       shop_id, bin_id,
       price, thc, cbd, total_cannabinoids,
       weight, last_audit_weight,
       count_original, count_last_audit, unit_weight,
       purchase_date, status
     ) VALUES (
       @id, @assetId, @productId,
       @shopId, @binId,
       @price, @thc, @cbd, @totalCannabinoids,
       @weight, @lastAuditWeight,
       @countOriginal, @countLastAudit, @unitWeight,
       @purchaseDate, 'active'
     )`,
  ).run({
    id,
    assetId,
    productId: body.productId,
    shopId: body.shopId ?? null,
    binId: body.binId ?? null,
    price: body.price,
    thc: body.thc ?? 0,
    cbd: body.cbd ?? 0,
    totalCannabinoids: body.totalCannabinoids ?? 0,
    weight: isDiscrete ? 0 : body.weight ?? 0,
    lastAuditWeight: isDiscrete ? null : body.weight ?? 0,
    countOriginal: isDiscrete ? body.countOriginal ?? 0 : 0,
    countLastAudit: isDiscrete ? body.countOriginal ?? 0 : null,
    unitWeight: isDiscrete ? body.unitWeight ?? 0 : 0,
    purchaseDate: body.purchaseDate,
  });

  res.json({ id, assetId });
});

// ─── Shared helpers (used by individual routes + batch) ───────────

type UpdateBody = Partial<{
  shopId: string | null;
  binId: string | null;
  price: number;
  thc: number;
  cbd: number;
  totalCannabinoids: number;
  weight: number;
  countOriginal: number;
  unitWeight: number;
  purchaseDate: string;
}>;

type ItemRow = {
  id: string;
  shop_id: string | null;
  bin_id: string | null;
  product_id: string;
  price: number;
  thc: number;
  cbd: number;
  total_cannabinoids: number;
  weight: number;
  last_audit_weight: number | null;
  count_original: number;
  count_last_audit: number | null;
  unit_weight: number;
  purchase_date: string;
};

function doUpdate(id: string, body: UpdateBody): void {
  const existing = db
    .prepare<[string], ItemRow>(
      `SELECT id, shop_id, bin_id, product_id, price, thc, cbd,
              total_cannabinoids, weight, last_audit_weight, count_original,
              count_last_audit, unit_weight, purchase_date
         FROM inventory_items WHERE id = ?`,
    )
    .get(id);
  if (!existing) throw new Error("inventory item not found");

  const product = db
    .prepare<[string], { kind: string }>(`SELECT kind FROM products WHERE id = ?`)
    .get(existing.product_id);
  const isDiscrete = product?.kind === "discrete";

  const auditCount = db
    .prepare<[string], { n: number }>(
      `SELECT COUNT(*) AS n FROM audits WHERE inventory_id = ?`,
    )
    .get(id)!.n;

  const nextShopId =
    body.shopId === undefined ? existing.shop_id : body.shopId || null;
  const nextBinId =
    body.binId === undefined ? existing.bin_id : body.binId || null;
  const nextPrice =
    Number.isFinite(body.price) && (body.price as number) >= 0
      ? (body.price as number)
      : existing.price;
  const nextPurchaseDate =
    typeof body.purchaseDate === "string" && body.purchaseDate.trim()
      ? body.purchaseDate.trim()
      : existing.purchase_date;
  const nextThc = Number.isFinite(body.thc) ? (body.thc as number) : existing.thc;
  const nextCbd = Number.isFinite(body.cbd) ? (body.cbd as number) : existing.cbd;
  const nextTotalCanna = Number.isFinite(body.totalCannabinoids)
    ? (body.totalCannabinoids as number)
    : existing.total_cannabinoids;

  const nextWeight =
    !isDiscrete && Number.isFinite(body.weight) && (body.weight as number) >= 0
      ? (body.weight as number)
      : existing.weight;
  const nextCountOriginal =
    isDiscrete && Number.isFinite(body.countOriginal) && (body.countOriginal as number) >= 0
      ? Math.floor(body.countOriginal as number)
      : existing.count_original;
  const nextUnitWeight =
    isDiscrete && Number.isFinite(body.unitWeight) && (body.unitWeight as number) >= 0
      ? (body.unitWeight as number)
      : existing.unit_weight;

  const nextLastAuditWeight =
    !isDiscrete && auditCount === 0 ? nextWeight : existing.last_audit_weight;
  const nextCountLastAudit =
    isDiscrete && auditCount === 0 ? nextCountOriginal : existing.count_last_audit;

  db.prepare(
    `UPDATE inventory_items SET
       shop_id = @shopId,
       bin_id = @binId,
       price = @price,
       thc = @thc,
       cbd = @cbd,
       total_cannabinoids = @totalCannabinoids,
       weight = @weight,
       last_audit_weight = @lastAuditWeight,
       count_original = @countOriginal,
       count_last_audit = @countLastAudit,
       unit_weight = @unitWeight,
       purchase_date = @purchaseDate
     WHERE id = @id`,
  ).run({
    id,
    shopId: nextShopId,
    binId: nextBinId,
    price: nextPrice,
    thc: nextThc,
    cbd: nextCbd,
    totalCannabinoids: nextTotalCanna,
    weight: nextWeight,
    lastAuditWeight: nextLastAuditWeight,
    countOriginal: nextCountOriginal,
    countLastAudit: nextCountLastAudit,
    unitWeight: nextUnitWeight,
    purchaseDate: nextPurchaseDate,
  });
}

function doCheckout(id: string, date: string): void {
  const result = db
    .prepare(
      `UPDATE inventory_items
         SET status = 'checked-out', checkout_date = ?, bin_id = NULL
       WHERE id = ? AND status = 'active'`,
    )
    .run(date, id);
  if (result.changes === 0) throw new Error("not found or not active");
}

function doCheckin(id: string, date: string, binId: string, remainingWeight?: number): void {
  const item = db
    .prepare<
      [string],
      { product_id: string; last_audit_weight: number | null; weight: number }
    >(
      `SELECT product_id, last_audit_weight, weight
         FROM inventory_items WHERE id = ? AND status = 'checked-out'`,
    )
    .get(id);
  if (!item) throw new Error("not found or not checked-out");

  const product = db
    .prepare<[string], { kind: string }>(`SELECT kind FROM products WHERE id = ?`)
    .get(item.product_id);
  const isBulk = product?.kind === "bulk";

  db.prepare(
    `UPDATE inventory_items
       SET status = 'active', bin_id = ?, checkout_date = NULL
     WHERE id = ?`,
  ).run(binId, id);

  if (isBulk && remainingWeight != null && Number.isFinite(remainingWeight)) {
    const prev = item.last_audit_weight ?? item.weight;
    db.prepare(
      `INSERT INTO audits (inventory_id, date, mode, value, prev_value, confirmed_by)
       VALUES (?, ?, 'weigh', ?, ?, 'checkin')`,
    ).run(id, date, remainingWeight, prev);
    db.prepare(`UPDATE inventory_items SET last_audit_weight = ? WHERE id = ?`).run(
      remainingWeight,
      id,
    );
  }
}

function doFinish(id: string, date: string, rating?: number, notes?: string): void {
  const result = db
    .prepare(
      `UPDATE inventory_items
         SET status = 'consumed', consumed_date = ?, rating = ?, notes = ?, bin_id = NULL, checkout_date = NULL
       WHERE id = ? AND status IN ('active', 'checked-out')`,
    )
    .run(date, rating ?? null, notes ?? null, id);
  if (result.changes === 0) throw new Error("not found or not active");
}

function doGone(id: string, date: string, reason: string, notes?: string): void {
  const combinedNotes = notes ? `${reason}: ${notes}` : reason;
  const result = db
    .prepare(
      `UPDATE inventory_items
         SET status = 'gone', gone_date = ?, notes = ?, bin_id = NULL, checkout_date = NULL
       WHERE id = ? AND status IN ('active', 'checked-out')`,
    )
    .run(date, combinedNotes, id);
  if (result.changes === 0) throw new Error("not found or not active");
  db.prepare(
    `INSERT INTO audits (inventory_id, date, mode, value, prev_value, confirmed_by)
     VALUES (?, ?, 'presence', 0, NULL, 'lost')`,
  ).run(id, date);
}

// ─── Individual routes (thin wrappers around helpers) ─────────────

inventoryRouter.patch("/inventory/:id", (req, res) => {
  try {
    doUpdate(req.params.id, req.body as UpdateBody);
    res.json({ ok: true });
  } catch (e: any) {
    res.status(404).json({ error: e.message });
  }
});

inventoryRouter.post("/inventory/:id/checkout", (req, res) => {
  try {
    doCheckout(req.params.id, (req.body as { date: string }).date);
    res.json({ ok: true });
  } catch (e: any) {
    res.status(404).json({ error: e.message });
  }
});

inventoryRouter.post("/inventory/:id/checkin", (req, res) => {
  const { date, binId, remainingWeight } = req.body as {
    date: string;
    binId: string;
    remainingWeight?: number;
  };
  try {
    doCheckin(req.params.id, date, binId, remainingWeight);
    res.json({ ok: true });
  } catch (e: any) {
    res.status(404).json({ error: e.message });
  }
});

inventoryRouter.post("/inventory/:id/finish", (req, res) => {
  const { date, rating, notes } = req.body as {
    date: string;
    rating?: number;
    notes?: string;
  };
  try {
    doFinish(req.params.id, date, rating, notes);
    res.json({ ok: true });
  } catch (e: any) {
    res.status(404).json({ error: e.message });
  }
});

inventoryRouter.post("/inventory/:id/gone", (req, res) => {
  const { date, reason, notes } = req.body as {
    date: string;
    reason: string;
    notes?: string;
  };
  try {
    doGone(req.params.id, date, reason, notes);
    res.json({ ok: true });
  } catch (e: any) {
    res.status(404).json({ error: e.message });
  }
});

inventoryRouter.post("/inventory/:id/audit", (req, res) => {
  const { id } = req.params;
  const { date, mode, value, confirmedBy } = req.body as {
    date: string;
    mode: "weigh" | "estimate" | "presence";
    value: number;
    confirmedBy?: string;
  };

  const item = db
    .prepare<
      [string],
      {
        product_id: string;
        weight: number;
        last_audit_weight: number | null;
        count_original: number;
        count_last_audit: number | null;
      }
    >(
      `SELECT product_id, weight, last_audit_weight, count_original, count_last_audit
         FROM inventory_items WHERE id = ?`,
    )
    .get(id);
  if (!item) return res.status(404).json({ error: "not found" });

  const product = db
    .prepare<[string], { kind: string }>(`SELECT kind FROM products WHERE id = ?`)
    .get(item.product_id);
  const isDiscrete = product?.kind === "discrete";

  const prev = isDiscrete
    ? item.count_last_audit ?? item.count_original
    : item.last_audit_weight ?? item.weight;

  const tx = db.transaction(() => {
    db.prepare(
      `INSERT INTO audits (inventory_id, date, mode, value, prev_value, confirmed_by)
       VALUES (?, ?, ?, ?, ?, ?)`,
    ).run(id, date, mode, value, prev, confirmedBy ?? null);
    if (isDiscrete) {
      db.prepare(`UPDATE inventory_items SET count_last_audit = ? WHERE id = ?`).run(
        value,
        id,
      );
    } else {
      db.prepare(`UPDATE inventory_items SET last_audit_weight = ? WHERE id = ?`).run(
        value,
        id,
      );
    }
  });
  tx();
  res.json({ ok: true });
});

// ─── Batch endpoint ───────────────────────────────────────────────

type BatchOp =
  | { action: "update"; id: string; fields: UpdateBody }
  | { action: "checkout"; id: string; date: string }
  | { action: "checkin"; id: string; date: string; binId: string }
  | { action: "finish"; id: string; date: string; rating?: number; notes?: string }
  | { action: "gone"; id: string; date: string; reason: string; notes?: string };

inventoryRouter.post("/inventory/batch", (req, res) => {
  const { ops } = req.body as { ops: BatchOp[] };

  if (!Array.isArray(ops) || ops.length === 0) {
    return res.status(400).json({ error: "ops array required" });
  }
  if (ops.length > 200) {
    return res.status(400).json({ error: "too many operations (max 200)" });
  }

  const tx = db.transaction(() => {
    for (const op of ops) {
      switch (op.action) {
        case "update":
          doUpdate(op.id, op.fields);
          break;
        case "checkout":
          doCheckout(op.id, op.date);
          break;
        case "checkin":
          doCheckin(op.id, op.date, op.binId);
          break;
        case "finish":
          doFinish(op.id, op.date, op.rating, op.notes);
          break;
        case "gone":
          doGone(op.id, op.date, op.reason, op.notes);
          break;
        default:
          throw new Error(`unknown action: ${(op as any).action}`);
      }
    }
  });

  try {
    tx();
    res.json({ ok: true, count: ops.length });
  } catch (e: any) {
    res.status(400).json({ error: e.message ?? "batch failed" });
  }
});