import type { InventoryItemOptionDto } from "@mrp/shared/dist/inventory/types.js";
import type { SalesCustomerOptionDto, SalesDocumentDetailDto, SalesDocumentInput, SalesLineInput } from "@mrp/shared/dist/sales/types.js";
import { useEffect, useState } from "react";
import { Link, useNavigate, useParams } from "react-router-dom";

import { useAuth } from "../../auth/AuthProvider";
import { api, ApiError } from "../../lib/api";
import { inventoryUnitOptions } from "../inventory/config";
import { emptySalesDocumentInput, salesConfigs, salesStatusOptions, type SalesDocumentEntity } from "./config";

export function SalesFormPage({ entity, mode }: { entity: SalesDocumentEntity; mode: "create" | "edit" }) {
  const { token } = useAuth();
  const navigate = useNavigate();
  const { quoteId, orderId } = useParams();
  const documentId = entity === "quote" ? quoteId : orderId;
  const config = salesConfigs[entity];
  const [form, setForm] = useState<SalesDocumentInput>(emptySalesDocumentInput);
  const [status, setStatus] = useState(mode === "create" ? `Create a new ${config.singularLabel.toLowerCase()}.` : `Loading ${config.singularLabel.toLowerCase()}...`);
  const [customers, setCustomers] = useState<SalesCustomerOptionDto[]>([]);
  const [customerSearchTerm, setCustomerSearchTerm] = useState("");
  const [customerPickerOpen, setCustomerPickerOpen] = useState(false);
  const [itemOptions, setItemOptions] = useState<InventoryItemOptionDto[]>([]);
  const [lineSearchTerms, setLineSearchTerms] = useState<string[]>([]);
  const [activeLinePicker, setActiveLinePicker] = useState<number | null>(null);
  const [isSaving, setIsSaving] = useState(false);

  const subtotal = form.lines.reduce((sum, line) => sum + line.quantity * line.unitPrice, 0);
  const discountAmount = subtotal * (form.discountPercent / 100);
  const taxableSubtotal = subtotal - discountAmount;
  const taxAmount = taxableSubtotal * (form.taxPercent / 100);
  const total = taxableSubtotal + taxAmount + form.freightAmount;

  useEffect(() => {
    if (!token) {
      return;
    }

    api.getSalesCustomers(token).then(setCustomers).catch(() => setCustomers([]));
    api.getInventoryItemOptions(token).then(setItemOptions).catch(() => setItemOptions([]));
  }, [token]);

  useEffect(() => {
    if (!token || mode !== "edit" || !documentId) {
      return;
    }

    const loader = entity === "quote" ? api.getQuote(token, documentId) : api.getSalesOrder(token, documentId);
    loader
      .then((document) => {
        setForm({
          customerId: document.customerId,
          status: document.status,
          issueDate: document.issueDate,
          expiresAt: entity === "quote" ? document.expiresAt : null,
          discountPercent: document.discountPercent,
          taxPercent: document.taxPercent,
          freightAmount: document.freightAmount,
          notes: document.notes,
          lines: document.lines.map((line) => ({
            itemId: line.itemId,
            description: line.description,
            quantity: line.quantity,
            unitOfMeasure: line.unitOfMeasure,
            unitPrice: line.unitPrice,
            position: line.position,
          })),
        });
        setCustomerSearchTerm(document.customerName);
        setLineSearchTerms(document.lines.map((line: SalesDocumentDetailDto["lines"][number]) => line.itemSku));
        setStatus(`${config.singularLabel} loaded.`);
      })
      .catch((error: unknown) => {
        const message = error instanceof ApiError ? error.message : `Unable to load ${config.singularLabel.toLowerCase()}.`;
        setStatus(message);
      });
  }, [config.singularLabel, documentId, entity, mode, token]);

  function updateField<Key extends keyof SalesDocumentInput>(key: Key, value: SalesDocumentInput[Key]) {
    setForm((current: SalesDocumentInput) => ({ ...current, [key]: value }));
  }

  function getSelectedCustomerName(customerId: string) {
    return customers.find((customer) => customer.id === customerId)?.name ?? "";
  }

  function getSelectedCustomer(customerId: string) {
    return customers.find((customer) => customer.id === customerId) ?? null;
  }

  function updateLine(index: number, nextLine: SalesLineInput) {
    setForm((current: SalesDocumentInput) => ({
      ...current,
      lines: current.lines.map((line: SalesLineInput, lineIndex: number) => (lineIndex === index ? nextLine : line)),
    }));
  }

  function updateLineSearchTerm(index: number, value: string) {
    setLineSearchTerms((current: string[]) => {
      const next = [...current];
      next[index] = value;
      return next;
    });
  }

  function addLine() {
    setForm((current: SalesDocumentInput) => ({
      ...current,
      lines: [
        ...current.lines,
        {
          itemId: "",
          description: "",
          quantity: 1,
          unitOfMeasure: "EA",
          unitPrice: 0,
          position: current.lines.length === 0 ? 10 : Math.max(...current.lines.map((line: SalesLineInput) => line.position)) + 10,
        },
      ],
    }));
    setLineSearchTerms((current: string[]) => [...current, ""]);
  }

  function removeLine(index: number) {
    setForm((current: SalesDocumentInput) => ({
      ...current,
      lines: current.lines.filter((_line: SalesLineInput, lineIndex: number) => lineIndex !== index),
    }));
    setLineSearchTerms((current: string[]) => current.filter((_term: string, termIndex: number) => termIndex !== index));
  }

  async function handleSubmit(event: React.FormEvent<HTMLFormElement>) {
    event.preventDefault();
    if (!token) {
      return;
    }

    setIsSaving(true);
    setStatus(`Saving ${config.singularLabel.toLowerCase()}...`);

    try {
      const saved =
        entity === "quote"
          ? mode === "create"
            ? await api.createQuote(token, form)
            : await api.updateQuote(token, documentId ?? "", form)
          : mode === "create"
            ? await api.createSalesOrder(token, { ...form, expiresAt: null })
            : await api.updateSalesOrder(token, documentId ?? "", { ...form, expiresAt: null });

      navigate(`${config.routeBase}/${saved.id}`);
    } catch (error: unknown) {
      const message = error instanceof ApiError ? error.message : `Unable to save ${config.singularLabel.toLowerCase()}.`;
      setStatus(message);
      setIsSaving(false);
    }
  }

  return (
    <form className="space-y-6" onSubmit={handleSubmit}>
      <section className="rounded-[28px] border border-line/70 bg-surface/90 p-4 shadow-panel 2xl:p-5">
        <div className="flex flex-col gap-3 lg:flex-row lg:items-start lg:justify-between">
          <div>
            <p className="text-xs font-semibold uppercase tracking-[0.24em] text-muted">{config.detailEyebrow} Editor</p>
            <h3 className="mt-2 text-xl font-bold text-text">{mode === "create" ? `New ${config.singularLabel}` : `Edit ${config.singularLabel}`}</h3>
          </div>
          <Link to={mode === "create" ? config.routeBase : `${config.routeBase}/${documentId}`} className="inline-flex items-center justify-center rounded-2xl border border-line/70 px-2 py-2 text-sm font-semibold text-text">
            Cancel
          </Link>
        </div>
      </section>
      <section className="space-y-4 rounded-[28px] border border-line/70 bg-surface/90 p-4 shadow-panel 2xl:p-5">
        <div className="grid gap-3 xl:grid-cols-4">
          <label className="block xl:col-span-2">
            <span className="mb-2 block text-sm font-semibold text-text">Customer</span>
            <div className="relative">
              <input
                value={customerSearchTerm}
                onChange={(event) => {
                  setCustomerSearchTerm(event.target.value);
                  updateField("customerId", "");
                  setCustomerPickerOpen(true);
                }}
                onFocus={() => setCustomerPickerOpen(true)}
                onBlur={() => {
                  window.setTimeout(() => {
                    setCustomerPickerOpen(false);
                    if (form.customerId) {
                      setCustomerSearchTerm(getSelectedCustomerName(form.customerId));
                    }
                  }, 120);
                }}
                placeholder="Search customer"
                className="w-full rounded-2xl border border-line/70 bg-page px-2 py-2 text-text outline-none transition focus:border-brand"
              />
              {customerPickerOpen ? (
                <div className="absolute z-20 mt-2 max-h-64 w-full overflow-y-auto rounded-2xl border border-line/70 bg-surface shadow-panel">
                  {customers
                    .filter((customer) => {
                      const query = customerSearchTerm.trim().toLowerCase();
                      if (!query) {
                        return true;
                      }

                      return (
                        customer.name.toLowerCase().includes(query) ||
                        customer.email.toLowerCase().includes(query)
                      );
                    })
                    .slice(0, 12)
                    .map((customer) => (
                      <button
                        key={customer.id}
                        type="button"
                        onMouseDown={(event) => {
                          event.preventDefault();
                          updateField("customerId", customer.id);
                          updateField("discountPercent", customer.resellerDiscountPercent);
                          setCustomerSearchTerm(customer.name);
                          setCustomerPickerOpen(false);
                        }}
                        className="block w-full border-b border-line/50 px-4 py-2 text-left text-sm transition last:border-b-0 hover:bg-page/70"
                      >
                        <div className="font-semibold text-text">{customer.name}</div>
                        <div className="mt-1 text-xs text-muted">{customer.email}</div>
                      </button>
                    ))}
                  {customers.filter((customer) => {
                    const query = customerSearchTerm.trim().toLowerCase();
                    if (!query) {
                      return true;
                    }

                    return customer.name.toLowerCase().includes(query) || customer.email.toLowerCase().includes(query);
                  }).length === 0 ? (
                    <div className="px-2 py-2 text-sm text-muted">No matching customers found.</div>
                  ) : null}
                </div>
              ) : null}
            </div>
            <div className="mt-2 min-h-5 text-xs text-muted">
              {form.customerId ? getSelectedCustomerName(form.customerId) : "No customer selected"}
            </div>
            {form.customerId ? (
              <div className="mt-1 text-xs text-muted">
                Default reseller discount: {getSelectedCustomer(form.customerId)?.resellerDiscountPercent.toFixed(2) ?? "0.00"}%
              </div>
            ) : null}
          </label>
          <label className="block">
            <span className="mb-2 block text-sm font-semibold text-text">Status</span>
            <select
              value={form.status}
              onChange={(event) => updateField("status", event.target.value as SalesDocumentInput["status"])}
              className="w-full rounded-2xl border border-line/70 bg-page px-2 py-2 text-text outline-none transition focus:border-brand"
            >
              {salesStatusOptions.map((option) => (
                <option key={option.value} value={option.value}>
                  {option.label}
                </option>
              ))}
            </select>
          </label>
          <label className="block">
            <span className="mb-2 block text-sm font-semibold text-text">Issue date</span>
            <input
              type="date"
              value={form.issueDate.slice(0, 10)}
              onChange={(event) => updateField("issueDate", new Date(event.target.value).toISOString())}
              className="w-full rounded-2xl border border-line/70 bg-page px-2 py-2 text-text outline-none transition focus:border-brand"
            />
          </label>
        </div>
        {entity === "quote" ? (
          <label className="block xl:max-w-sm">
            <span className="mb-2 block text-sm font-semibold text-text">Expiration date</span>
            <input
              type="date"
              value={form.expiresAt ? form.expiresAt.slice(0, 10) : ""}
              onChange={(event) => updateField("expiresAt", event.target.value ? new Date(event.target.value).toISOString() : null)}
              className="w-full rounded-2xl border border-line/70 bg-page px-2 py-2 text-text outline-none transition focus:border-brand"
            />
          </label>
        ) : null}
        <label className="block">
          <span className="mb-2 block text-sm font-semibold text-text">Notes</span>
          <textarea
            value={form.notes}
            onChange={(event) => updateField("notes", event.target.value)}
            rows={3}
            className="w-full rounded-3xl border border-line/70 bg-page px-2 py-2 text-text outline-none transition focus:border-brand"
          />
        </label>
        <div className="grid gap-3 xl:grid-cols-3">
          <label className="block">
            <span className="mb-2 block text-sm font-semibold text-text">Discount %</span>
            <input
              type="number"
              min={0}
              max={100}
              step={0.01}
              value={form.discountPercent}
              onChange={(event) => updateField("discountPercent", Number(event.target.value) || 0)}
              className="w-full rounded-2xl border border-line/70 bg-page px-2 py-2 text-text outline-none transition focus:border-brand"
            />
          </label>
          <label className="block">
            <span className="mb-2 block text-sm font-semibold text-text">Tax %</span>
            <input
              type="number"
              min={0}
              max={100}
              step={0.01}
              value={form.taxPercent}
              onChange={(event) => updateField("taxPercent", Number(event.target.value) || 0)}
              className="w-full rounded-2xl border border-line/70 bg-page px-2 py-2 text-text outline-none transition focus:border-brand"
            />
          </label>
          <label className="block">
            <span className="mb-2 block text-sm font-semibold text-text">Freight</span>
            <input
              type="number"
              min={0}
              step={0.01}
              value={form.freightAmount}
              onChange={(event) => updateField("freightAmount", Number(event.target.value) || 0)}
              className="w-full rounded-2xl border border-line/70 bg-page px-2 py-2 text-text outline-none transition focus:border-brand"
            />
          </label>
        </div>
      </section>
      <section className="rounded-[28px] border border-line/70 bg-surface/90 p-4 shadow-panel 2xl:p-5">
        <div className="flex flex-col gap-3 lg:flex-row lg:items-start lg:justify-between">
          <div>
            <p className="text-xs font-semibold uppercase tracking-[0.24em] text-muted">Line Items</p>
            <h4 className="mt-2 text-lg font-bold text-text">Commercial lines</h4>
          </div>
          <button type="button" onClick={addLine} className="inline-flex items-center justify-center rounded-2xl border border-line/70 px-2 py-2 text-sm font-semibold text-text">
            Add line
          </button>
        </div>
        {form.lines.length === 0 ? (
          <div className="mt-5 rounded-3xl border border-dashed border-line/70 bg-page/60 px-4 py-8 text-center text-sm text-muted">
            No line items added yet.
          </div>
        ) : (
          <div className="mt-5 space-y-4">
            {form.lines.map((line: SalesLineInput, index: number) => (
              <div key={index} className="rounded-3xl border border-line/70 bg-page/60 p-3">
                <div className="grid gap-3 xl:grid-cols-[1.15fr_1.25fr_0.5fr_0.55fr_0.7fr_0.75fr_auto]">
                  <label className="block">
                    <span className="mb-2 block text-xs font-semibold uppercase tracking-[0.16em] text-muted">SKU</span>
                    <div className="relative">
                      <input
                        value={lineSearchTerms[index] ?? ""}
                        onChange={(event) => {
                          updateLineSearchTerm(index, event.target.value);
                          updateLine(index, { ...line, itemId: "" });
                          setActiveLinePicker(index);
                        }}
                        onFocus={() => setActiveLinePicker(index)}
                        onBlur={() => window.setTimeout(() => setActiveLinePicker((current) => (current === index ? null : current)), 120)}
                        placeholder="Search by SKU"
                        className="w-full rounded-2xl border border-line/70 bg-surface px-2 py-2 text-text outline-none transition focus:border-brand"
                      />
                      {activeLinePicker === index ? (
                        <div className="absolute z-20 mt-2 max-h-64 w-full overflow-y-auto rounded-2xl border border-line/70 bg-surface shadow-panel">
                          {itemOptions
                            .filter((option) => option.sku.toLowerCase().includes((lineSearchTerms[index] ?? "").trim().toLowerCase()))
                            .slice(0, 12)
                            .map((option) => (
                              <button
                                key={option.id}
                                type="button"
                                onMouseDown={(event) => {
                                  event.preventDefault();
                                  updateLine(index, {
                                    ...line,
                                    itemId: option.id,
                                    description: line.description || option.name,
                                    unitPrice: line.unitPrice > 0 ? line.unitPrice : (option.defaultPrice ?? 0),
                                  });
                                  updateLineSearchTerm(index, option.sku);
                                  setActiveLinePicker(null);
                                }}
                                className="block w-full border-b border-line/50 px-4 py-2 text-left text-sm font-semibold text-text transition last:border-b-0 hover:bg-page/70"
                              >
                                {option.sku}
                              </button>
                            ))}
                        </div>
                      ) : null}
                    </div>
                  </label>
                  <label className="block">
                    <span className="mb-2 block text-xs font-semibold uppercase tracking-[0.16em] text-muted">Description</span>
                    <input value={line.description} onChange={(event) => updateLine(index, { ...line, description: event.target.value })} className="w-full rounded-2xl border border-line/70 bg-surface px-2 py-2 text-text outline-none transition focus:border-brand" />
                  </label>
                  <label className="block">
                    <span className="mb-2 block text-xs font-semibold uppercase tracking-[0.16em] text-muted">Qty</span>
                    <input type="number" min={1} step={1} value={line.quantity} onChange={(event) => updateLine(index, { ...line, quantity: Number.parseInt(event.target.value, 10) || 0 })} className="w-full rounded-2xl border border-line/70 bg-surface px-2 py-2 text-text outline-none transition focus:border-brand" />
                  </label>
                  <label className="block">
                    <span className="mb-2 block text-xs font-semibold uppercase tracking-[0.16em] text-muted">UOM</span>
                    <select value={line.unitOfMeasure} onChange={(event) => updateLine(index, { ...line, unitOfMeasure: event.target.value as SalesLineInput["unitOfMeasure"] })} className="w-full rounded-2xl border border-line/70 bg-surface px-2 py-2 text-text outline-none transition focus:border-brand">
                      {inventoryUnitOptions.map((option) => (
                        <option key={option.value} value={option.value}>
                          {option.label}
                        </option>
                      ))}
                    </select>
                  </label>
                  <label className="block">
                    <span className="mb-2 block text-xs font-semibold uppercase tracking-[0.16em] text-muted">Unit Price</span>
                    <input type="number" min={0} step={0.01} value={line.unitPrice} onChange={(event) => updateLine(index, { ...line, unitPrice: Number(event.target.value) })} className="w-full rounded-2xl border border-line/70 bg-surface px-2 py-2 text-text outline-none transition focus:border-brand" />
                  </label>
                  <div className="flex items-end">
                    <div className="w-full rounded-2xl border border-line/70 bg-surface px-2 py-2 text-sm text-text">
                      ${(line.quantity * line.unitPrice).toFixed(2)}
                    </div>
                  </div>
                  <div className="flex items-end">
                    <button type="button" onClick={() => removeLine(index)} className="rounded-2xl border border-rose-400/40 px-2 py-2 text-sm font-semibold text-rose-700 dark:text-rose-300">
                      Remove
                    </button>
                  </div>
                </div>
              </div>
            ))}
          </div>
        )}
        <div className="mt-5 grid gap-3 md:grid-cols-2 xl:grid-cols-4">
          <div className="rounded-2xl border border-line/70 bg-page/60 px-2 py-2 text-sm">
            <div className="text-xs font-semibold uppercase tracking-[0.16em] text-muted">Subtotal</div>
            <div className="mt-1 font-semibold text-text">${subtotal.toFixed(2)}</div>
          </div>
          <div className="rounded-2xl border border-line/70 bg-page/60 px-2 py-2 text-sm">
            <div className="text-xs font-semibold uppercase tracking-[0.16em] text-muted">Discount</div>
            <div className="mt-1 font-semibold text-text">-${discountAmount.toFixed(2)}</div>
          </div>
          <div className="rounded-2xl border border-line/70 bg-page/60 px-2 py-2 text-sm">
            <div className="text-xs font-semibold uppercase tracking-[0.16em] text-muted">Tax + Freight</div>
            <div className="mt-1 font-semibold text-text">${(taxAmount + form.freightAmount).toFixed(2)}</div>
          </div>
          <div className="rounded-2xl border border-line/70 bg-page/60 px-2 py-2 text-sm">
            <div className="text-xs font-semibold uppercase tracking-[0.16em] text-muted">Total</div>
            <div className="mt-1 font-semibold text-text">${total.toFixed(2)}</div>
          </div>
        </div>
        <div className="mt-6 flex flex-col gap-3 rounded-2xl border border-line/70 bg-page/70 px-2 py-2 sm:flex-row sm:items-center sm:justify-between">
          <span className="min-w-0 text-sm text-muted">{status}</span>
          <button type="submit" disabled={isSaving} className="rounded-2xl bg-brand px-2 py-2 text-sm font-semibold text-white disabled:cursor-not-allowed disabled:opacity-60">
            {isSaving ? "Saving..." : mode === "create" ? `Create ${config.singularLabel.toLowerCase()}` : "Save changes"}
          </button>
        </div>
      </section>
    </form>
  );
}