import { useMutation, useQuery } from "@tanstack/react-query";
import { useMemo, useState } from "react";
import { useNavigate } from "react-router-dom";
import { api, type AvailableCriterion } from "../api";
import { CriteriaControl, pickSource } from "../components/CriteriaControl";
import { EmptyState, ErrorState, LoadingState } from "../components/State";

type Draft = Record<string, { operator: string; value: unknown }>;

export function WizardPage() {
  const navigate = useNavigate();
  const categories = useQuery({ queryKey: ["product-categories"], queryFn: api.productCategories });
  const [name, setName] = useState("");
  const [categoryId, setCategoryId] = useState("");
  const [market, setMarket] = useState("DE");
  const [currency, setCurrency] = useState("EUR");
  const [budget, setBudget] = useState("");
  const [sourceOverride, setSourceOverride] = useState<string | null>(null);
  const [selected, setSelected] = useState<string[]>([]);
  const [draft, setDraft] = useState<Draft>({});

  const sources = useQuery({
    queryKey: ["category-sources", categoryId],
    queryFn: () => api.categorySources(categoryId),
    enabled: Boolean(categoryId),
  });
  const source = sourceOverride || pickSource(sources.data?.items || []);
  const criteria = useQuery({
    queryKey: ["available-criteria", categoryId, source],
    queryFn: () => api.availableCriteria(categoryId, source!),
    enabled: Boolean(categoryId && source),
  });
  const create = useMutation({
    mutationFn: async () => {
      if (!source || !sources.data) throw new Error("Keine Source verfügbar");
      const chosen = (criteria.data?.criteria || []).filter((item) => selected.includes(item.criterion_definition_id));
      const project = await api.createProject({
        name,
        product_category_id: categoryId,
        market,
        currency,
        target_budget: budget || null,
        criteria: {
          items: chosen.map((item) => ({
            criterion_definition_id: item.criterion_definition_id,
            operator: draft[item.criterion_definition_id]?.operator || item.operators[0] || ">=",
            value: coerce(item, draft[item.criterion_definition_id]?.value),
            enabled_for_discovery: true,
          })),
        },
      });
      const sourceRow = sources.data.items.find((item) => item.source === source) || sources.data.items[0];
      await api.createSearch(project.id, {
        source_id: sourceRow.source,
        source_category_id: sourceRow.source_category_id,
      });
      return project;
    },
    onSuccess: (project) => navigate(`/projects/${project.id}`),
  });

  const sourceItems = sources.data?.items || [];
  const needsPicker = sourceItems.filter((item) => item.status === "ACTIVE").length > 1;

  const visible = useMemo(() => criteria.data?.criteria || [], [criteria.data]);

  if (categories.isLoading) return <LoadingState />;
  if (categories.isError) return <ErrorState message={(categories.error as Error).message} />;

  return (
    <section className="grid">
      <h1>Neues Projekt</h1>
      <div className="card grid">
        <label>
          Projektname
          <input value={name} onChange={(event) => setName(event.target.value)} />
        </label>
        <label>
          Produktkategorie
          <select
            value={categoryId}
            onChange={(event) => {
              setCategoryId(event.target.value);
              setSourceOverride(null);
              setSelected([]);
            }}
          >
            <option value="">Bitte wählen</option>
            {(categories.data?.items || []).map((item) => (
              <option key={item.id} value={item.id}>
                {item.name}
              </option>
            ))}
          </select>
        </label>
        <div className="row">
          <label>
            Markt
            <input value={market} onChange={(event) => setMarket(event.target.value)} />
          </label>
          <label>
            Währung
            <input value={currency} onChange={(event) => setCurrency(event.target.value)} />
          </label>
          <label>
            Zielbudget optional
            <input value={budget} onChange={(event) => setBudget(event.target.value)} />
          </label>
        </div>
      </div>

      {categoryId && sources.isLoading ? <LoadingState /> : null}
      {categoryId && !sources.isLoading && sourceItems.length === 0 ? (
        <EmptyState>Keine Source für diese Produktkategorie verfügbar.</EmptyState>
      ) : null}
      {needsPicker ? (
        <label>
          Quelle
          <select value={source || ""} onChange={(event) => setSourceOverride(event.target.value)}>
            {sourceItems.map((item) => (
              <option key={item.source} value={item.source}>
                {item.display_name}
              </option>
            ))}
          </select>
        </label>
      ) : source ? (
        <p className="muted">Quelle: {source}</p>
      ) : null}

      {criteria.isLoading ? <LoadingState /> : null}
      {visible.length > 0 ? (
        <div className="card grid">
          {visible.map((item) => {
            const on = selected.includes(item.criterion_definition_id);
            return (
              <div key={item.criterion_definition_id}>
                <label>
                  <input
                    type="checkbox"
                    checked={on}
                    onChange={(event) => {
                      setSelected((current) =>
                        event.target.checked
                          ? [...current, item.criterion_definition_id]
                          : current.filter((id) => id !== item.criterion_definition_id),
                      );
                      setDraft((current) => ({
                        ...current,
                        [item.criterion_definition_id]: current[item.criterion_definition_id] || {
                          operator: item.operators[0] || ">=",
                          value: "",
                        },
                      }));
                    }}
                  />{" "}
                  {item.label}
                </label>
                {on ? (
                  <CriteriaControl
                    criterion={item}
                    operator={draft[item.criterion_definition_id]?.operator || item.operators[0] || ">="}
                    value={draft[item.criterion_definition_id]?.value}
                    onChange={(next) => setDraft((current) => ({ ...current, [item.criterion_definition_id]: next }))}
                  />
                ) : null}
              </div>
            );
          })}
        </div>
      ) : null}

      {create.isError ? <ErrorState message={(create.error as Error).message} /> : null}
      <button className="button" disabled={!name || !categoryId || selected.length === 0 || create.isPending} onClick={() => create.mutate()}>
        Projekt speichern
      </button>
    </section>
  );
}

function coerce(criterion: AvailableCriterion, value: unknown) {
  if (value == null || value === "") return value;
  if ((criterion.filter_type || "").startsWith("NUMERIC")) return Number(value);
  return value;
}