import { eq } from "drizzle-orm";
import { Hono } from "hono";
import type { Db, DbHandle } from "../db/client.js";
import type { DocumentsStore } from "../documents.js";
import { documents, invoiceLines, invoices, vendors } from "../db/schema/index.js";
import type { AppBindings } from "../auth/middleware.js";
import { errorJson } from "../http.js";
import { applyMatchingPolicy, closePendingSteps } from "../approvals.js";
import {
  asMoney,
  asString,
  caller,
  firstById,
  isDateOnly,
  isUniqueViolation,
  iso,
  isUuid,
  moneyCents,
  newId,
  optionalString,
  parseJsonBody,
  requireCan,
  rowsOf,
} from "./helpers.js";

const PAYMENT_METHODS = ["check", "ach"] as const;

type InvoiceRow = typeof invoices.$inferSelect;
type LineRow = typeof invoiceLines.$inferSelect;
type DocumentRow = typeof documents.$inferSelect;
type VendorRow = typeof vendors.$inferSelect;
type LineInput = {
  description: string;
  amount: string;
  glAccountId: string | null;
  departmentId: string | null;
};

function isPaymentMethod(value: string): value is (typeof PAYMENT_METHODS)[number] {
  return (PAYMENT_METHODS as readonly string[]).includes(value);
}

function toInvoice(row: InvoiceRow, lines: LineRow[]) {
  return {
    id: row.id,
    vendorId: row.vendorId,
    invoiceNumber: row.invoiceNumber,
    amount: row.amount,
    amountDue: row.amountDue,
    dueDate: row.dueDate,
    payDate: row.payDate,
    sendPaymentOn: row.sendPaymentOn,
    status: row.status,
    paymentMethod: row.paymentMethod,
    memo: row.memo,
    createdAt: iso(row.createdAt),
    updatedAt: iso(row.updatedAt),
    lines: lines.map(toLine),
  };
}

function toLine(row: LineRow) {
  return {
    id: row.id,
    invoiceId: row.invoiceId,
    description: row.description,
    amount: row.amount,
    glAccountId: row.glAccountId,
    departmentId: row.departmentId,
    createdAt: iso(row.createdAt),
  };
}

function toDocument(
  row: DocumentRow,
  urls: { uploadUrl?: string; uploadHeaders?: Record<string, string>; downloadUrl?: string } = {},
) {
  return {
    id: row.id,
    invoiceId: row.invoiceId,
    objectKey: row.objectKey,
    contentType: row.contentType,
    fileName: row.fileName,
    uploadedByUserId: row.uploadedByUserId,
    createdAt: iso(row.createdAt),
    ...urls,
  };
}

function parseLine(body: Record<string, unknown>): LineInput | string {
  const description = asString(body.description).trim();
  const amount = asMoney(body.amount);
  if (!description || !amount) return "Line description and amount are required.";
  const glAccountId = optionalString(body.glAccountId) ?? null;
  const departmentId = optionalString(body.departmentId) ?? null;
  if (glAccountId && !isUuid(glAccountId)) return "Invalid glAccountId.";
  if (departmentId && !isUuid(departmentId)) return "Invalid departmentId.";
  return { description, amount, glAccountId, departmentId };
}

function linesSumToAmount(lines: Array<{ amount: string }>, amount: string): boolean {
  const sum = lines.reduce((total, line) => total + moneyCents(line.amount), 0);
  return sum === moneyCents(amount);
}

async function linesFor(handle: DbHandle, invoiceId: string): Promise<LineRow[]> {
  const rows = await rowsOf<LineRow>(handle, invoiceLines);
  return rows.filter((row) => row.invoiceId === invoiceId);
}

async function activeDuplicate(
  handle: DbHandle,
  vendorId: string,
  invoiceNumber: string,
  exceptId?: string,
): Promise<boolean> {
  const rows = await rowsOf<InvoiceRow>(handle, invoices);
  return rows.some(
    (row) =>
      row.vendorId === vendorId &&
      row.invoiceNumber === invoiceNumber &&
      row.status !== "void" &&
      row.id !== exceptId,
  );
}

function safeFileName(value: string): string {
  return (
    value
      .replace(/[/\\]+/g, "_")
      .replace(/^\.+/, "_")
      .slice(0, 180) || "document"
  );
}

export function createInvoiceRoutes(handle: Db, store: DocumentsStore) {
  const routes = new Hono<AppBindings>();

  routes.get("/invoices", async (c) => {
    const denied = requireCan(c, "read:invoices");
    if (denied) return denied;
    const rows = await rowsOf<InvoiceRow>(handle, invoices);
    const allLines = await rowsOf<LineRow>(handle, invoiceLines);
    return c.json({
      items: rows.map((row) =>
        toInvoice(
          row,
          allLines.filter((line) => line.invoiceId === row.id),
        ),
      ),
    });
  });

  routes.get("/invoices/:id", async (c) => {
    const denied = requireCan(c, "read:invoices");
    if (denied) return denied;
    const id = c.req.param("id");
    if (!isUuid(id)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid invoice id.");
    const row = await firstById<InvoiceRow>(handle, invoices, id);
    if (!row) return errorJson(c, 404, "NOT_FOUND", "Invoice not found.");
    return c.json(toInvoice(row, await linesFor(handle, id)));
  });

  routes.post("/invoices", async (c) => {
    const denied = requireCan(c, "write:invoices");
    if (denied) return denied;
    const body = await parseJsonBody(c);
    const vendorId = asString(body.vendorId);
    const invoiceNumber = asString(body.invoiceNumber).trim();
    const amount = asMoney(body.amount);
    const dueDate = asString(body.dueDate);
    if (!isUuid(vendorId) || !invoiceNumber || !amount || !isDateOnly(dueDate)) {
      return errorJson(
        c,
        400,
        "VALIDATION_ERROR",
        "vendorId, invoiceNumber, amount, and dueDate are required.",
      );
    }
    const vendor = await firstById<VendorRow>(handle, vendors, vendorId);
    if (!vendor) return errorJson(c, 400, "VALIDATION_ERROR", "Vendor not found.");
    const method = asString(body.paymentMethod, vendor.defaultPaymentMethod);
    if (!isPaymentMethod(method)) {
      return errorJson(c, 400, "VALIDATION_ERROR", "Invalid paymentMethod.");
    }
    const parsedLines: LineInput[] = [];
    if (Array.isArray(body.lines)) {
      for (const raw of body.lines) {
        if (!raw || typeof raw !== "object") {
          return errorJson(c, 400, "VALIDATION_ERROR", "Each line must be an object.");
        }
        const parsed = parseLine(raw as Record<string, unknown>);
        if (typeof parsed === "string") return errorJson(c, 400, "VALIDATION_ERROR", parsed);
        parsedLines.push(parsed);
      }
      if (!linesSumToAmount(parsedLines, amount)) {
        return errorJson(
          c,
          400,
          "VALIDATION_ERROR",
          "Line amounts must sum to the invoice amount.",
        );
      }
    }
    if (await activeDuplicate(handle, vendorId, invoiceNumber)) {
      return errorJson(
        c,
        409,
        "CONFLICT",
        "An active invoice already uses this vendor and invoice number.",
      );
    }
    let latest: InvoiceRow | undefined;
    let currentLines: LineRow[] = [];
    try {
      await handle.db.transaction(async (tx) => {
        const scoped: DbHandle = { db: tx };
        const [row] = await tx
          .insert(invoices)
          .values({
            vendorId,
            invoiceNumber,
            amount,
            amountDue: amount,
            dueDate,
            paymentMethod: method,
            memo: asString(body.memo),
            status: "pending_approval",
          })
          .returning();
        for (const line of parsedLines) {
          await tx
            .insert(invoiceLines)
            .values({ invoiceId: row.id, ...line })
            .returning();
        }
        latest = await applyMatchingPolicy(scoped, row, caller(c).id);
        currentLines = await linesFor(scoped, row.id);
      });
    } catch (error) {
      if (isUniqueViolation(error)) {
        return errorJson(
          c,
          409,
          "CONFLICT",
          "An active invoice already uses this vendor and invoice number.",
        );
      }
      throw error;
    }
    if (!latest) {
      return errorJson(c, 500, "INTERNAL_ERROR", "Invoice create did not complete.");
    }
    return c.json(toInvoice(latest, currentLines), 201);
  });

  routes.patch("/invoices/:id", async (c) => {
    const denied = requireCan(c, "write:invoices");
    if (denied) return denied;
    const id = c.req.param("id");
    if (!isUuid(id)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid invoice id.");
    const existing = await firstById<InvoiceRow>(handle, invoices, id);
    if (!existing) return errorJson(c, 404, "NOT_FOUND", "Invoice not found.");
    const body = await parseJsonBody(c);
    const patch: Partial<typeof invoices.$inferInsert> = { id, updatedAt: new Date() };
    if (body.vendorId !== undefined) {
      const vendorId = asString(body.vendorId);
      if (!isUuid(vendorId)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid vendorId.");
      patch.vendorId = vendorId;
    }
    if (body.invoiceNumber !== undefined) {
      const invoiceNumber = asString(body.invoiceNumber).trim();
      if (!invoiceNumber)
        return errorJson(c, 400, "VALIDATION_ERROR", "invoiceNumber is required.");
      patch.invoiceNumber = invoiceNumber;
    }
    if (body.amount !== undefined) {
      const amount = asMoney(body.amount);
      if (!amount) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid amount.");
      patch.amount = amount;
      patch.amountDue = amount;
    }
    if (body.dueDate !== undefined) {
      const dueDate = asString(body.dueDate);
      if (!isDateOnly(dueDate)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid dueDate.");
      patch.dueDate = dueDate;
    }
    if (body.payDate !== undefined) {
      const payDate = optionalString(body.payDate) ?? null;
      if (payDate && !isDateOnly(payDate))
        return errorJson(c, 400, "VALIDATION_ERROR", "Invalid payDate.");
      patch.payDate = payDate;
    }
    if (body.sendPaymentOn !== undefined) {
      const sendPaymentOn = optionalString(body.sendPaymentOn) ?? null;
      if (sendPaymentOn && !isDateOnly(sendPaymentOn)) {
        return errorJson(c, 400, "VALIDATION_ERROR", "Invalid sendPaymentOn.");
      }
      patch.sendPaymentOn = sendPaymentOn;
    }
    if (body.status !== undefined) {
      const status = asString(body.status);
      if (status !== "void") {
        return errorJson(
          c,
          400,
          "VALIDATION_ERROR",
          "PATCH may only set status to void. Approval and payment statuses go through decision routes.",
        );
      }
      patch.status = "void";
    }
    if (body.paymentMethod !== undefined) {
      const method = asString(body.paymentMethod);
      if (!isPaymentMethod(method))
        return errorJson(c, 400, "VALIDATION_ERROR", "Invalid paymentMethod.");
      patch.paymentMethod = method;
    }
    if (body.memo !== undefined) patch.memo = asString(body.memo);
    const nextVendor = patch.vendorId ?? existing.vendorId;
    const nextNumber = patch.invoiceNumber ?? existing.invoiceNumber;
    const nextStatus = patch.status ?? existing.status;
    if (nextStatus !== "void" && (await activeDuplicate(handle, nextVendor, nextNumber, id))) {
      return errorJson(
        c,
        409,
        "CONFLICT",
        "An active invoice already uses this vendor and invoice number.",
      );
    }
    const nextAmount = patch.amount ?? existing.amount;
    const currentLines = await linesFor(handle, id);
    if (currentLines.length > 0 && !linesSumToAmount(currentLines, nextAmount)) {
      return errorJson(c, 400, "VALIDATION_ERROR", "Line amounts must sum to the invoice amount.");
    }
    let row: InvoiceRow;
    try {
      if (patch.status === "void") {
        await closePendingSteps(handle, id, caller(c).id);
      }
      [row] = await handle.db.update(invoices).set(patch).where(eq(invoices.id, id)).returning();
    } catch (error) {
      if (isUniqueViolation(error)) {
        return errorJson(
          c,
          409,
          "CONFLICT",
          "An active invoice already uses this vendor and invoice number.",
        );
      }
      throw error;
    }
    return c.json(toInvoice(row, currentLines));
  });

  routes.post("/invoices/:id/lines", async (c) => {
    const denied = requireCan(c, "write:invoices");
    if (denied) return denied;
    const id = c.req.param("id");
    if (!isUuid(id)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid invoice id.");
    const invoice = await firstById<InvoiceRow>(handle, invoices, id);
    if (!invoice) return errorJson(c, 404, "NOT_FOUND", "Invoice not found.");
    const parsed = parseLine(await parseJsonBody(c));
    if (typeof parsed === "string") return errorJson(c, 400, "VALIDATION_ERROR", parsed);
    const [row] = await handle.db
      .insert(invoiceLines)
      .values({ invoiceId: id, ...parsed })
      .returning();
    return c.json(toLine(row), 201);
  });

  routes.put("/invoices/:id/lines", async (c) => {
    const denied = requireCan(c, "write:invoices");
    if (denied) return denied;
    const id = c.req.param("id");
    if (!isUuid(id)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid invoice id.");
    const invoice = await firstById<InvoiceRow>(handle, invoices, id);
    if (!invoice) return errorJson(c, 404, "NOT_FOUND", "Invoice not found.");
    const body = await parseJsonBody(c);
    if (!Array.isArray(body.items)) {
      return errorJson(c, 400, "VALIDATION_ERROR", "items must be an array of lines.");
    }
    const parsedLines: LineInput[] = [];
    for (const raw of body.items) {
      if (!raw || typeof raw !== "object") {
        return errorJson(c, 400, "VALIDATION_ERROR", "Each line must be an object.");
      }
      const parsed = parseLine(raw as Record<string, unknown>);
      if (typeof parsed === "string") return errorJson(c, 400, "VALIDATION_ERROR", parsed);
      parsedLines.push(parsed);
    }
    if (!linesSumToAmount(parsedLines, invoice.amount)) {
      return errorJson(c, 400, "VALIDATION_ERROR", "Line amounts must sum to the invoice amount.");
    }
    const created: LineRow[] = [];
    await handle.db.transaction(async (tx) => {
      await tx.delete(invoiceLines).where(eq(invoiceLines.invoiceId, id));
      for (const line of parsedLines) {
        const [row] = await tx
          .insert(invoiceLines)
          .values({ invoiceId: id, ...line })
          .returning();
        created.push(row);
      }
    });
    return c.json({ items: created.map(toLine) });
  });

  routes.post("/invoices/:id/documents", async (c) => {
    const denied = requireCan(c, "write:invoices");
    if (denied) return denied;
    const id = c.req.param("id");
    if (!isUuid(id)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid invoice id.");
    const invoice = await firstById<InvoiceRow>(handle, invoices, id);
    if (!invoice) return errorJson(c, 404, "NOT_FOUND", "Invoice not found.");
    const body = await parseJsonBody(c);
    const fileName = safeFileName(asString(body.fileName).trim());
    const contentType = asString(body.contentType, "application/pdf").trim() || "application/pdf";
    if (!asString(body.fileName).trim()) {
      return errorJson(c, 400, "VALIDATION_ERROR", "fileName is required.");
    }
    const documentId = newId();
    const objectKey = `invoices/${id}/${documentId}/${fileName}`;
    const [row] = await handle.db
      .insert(documents)
      .values({
        id: documentId,
        invoiceId: id,
        objectKey,
        contentType,
        fileName,
        uploadedByUserId: caller(c).id,
      })
      .returning();
    const put = await store.presignPut({ objectKey, contentType });
    return c.json(toDocument(row, { uploadUrl: put.url, uploadHeaders: put.headers }), 201);
  });

  routes.post("/documents/:id/confirmations", async (c) => {
    const denied = requireCan(c, "write:invoices");
    if (denied) return denied;
    const id = c.req.param("id");
    if (!isUuid(id)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid document id.");
    const row = await firstById<DocumentRow>(handle, documents, id);
    if (!row) return errorJson(c, 404, "NOT_FOUND", "Document not found.");
    if (!(await store.objectExists(row.objectKey))) {
      return errorJson(c, 409, "CONFLICT", "Object has not been uploaded.");
    }
    return c.json(toDocument(row, { downloadUrl: await store.presignGet(row.objectKey) }));
  });

  routes.get("/documents/:id", async (c) => {
    const denied = requireCan(c, "read:invoices");
    if (denied) return denied;
    const id = c.req.param("id");
    if (!isUuid(id)) return errorJson(c, 400, "VALIDATION_ERROR", "Invalid document id.");
    const row = await firstById<DocumentRow>(handle, documents, id);
    if (!row) return errorJson(c, 404, "NOT_FOUND", "Document not found.");
    return c.json(toDocument(row, { downloadUrl: await store.presignGet(row.objectKey) }));
  });

  return routes;
}