// Create / edit list dialog, shared by the dashboard and the list editor.
import { h, icon, api, openDialog, dialogHead, busy, fmt } from "./common.js";

const SIZE_PRESETS = [5, 10, 25, 50, 100];

function sizeHint(n, limits) {
  if (!Number.isInteger(n) || n < 1) return { text: "Pick a size of at least 1.", cls: "is-error" };
  if (n > limits.max) return { text: `The most a list can hold is ${fmt.format(limits.max)}.`, cls: "is-error" };
  if (n > limits.warn) return { text: `That's a lot. Lists this long work, but they're hard to browse and rank. ${limits.recommended} or fewer is recommended.`, cls: "is-warn" };
  if (n > limits.recommended) return { text: `Heads up: ${limits.recommended} or fewer is recommended so visitors can take it all in.`, cls: "is-warn" };
  return { text: `Up to ${fmt.format(limits.max)} allowed; ${limits.recommended} or fewer recommended.`, cls: "" };
}

const autoTitle = (n, cat) => `Top ${n} ${cat.label}`;

/**
 * @param {object} o
 * @param {object[]} o.categories
 * @param {object} o.limits
 * @param {object} [o.list]      existing list to edit
 * @param {string} [o.category]  preselected category for a new list
 * @param {(list: object) => void} o.onSaved
 */
export function openListForm({ categories, limits, list, category, onSaved }) {
  const editing = !!list;
  const catByKey = Object.fromEntries(categories.map((c) => [c.key, c]));
  const state = {
    category: list?.category || category || categories[0].key,
    size: list?.maxItems || 10,
  };
  // Keep the title in sync with size/category until the owner types their own.
  let titleTouched = editing && list.title !== autoTitle(list.maxItems, catByKey[list.category]);

  const title = h("input", { name: "title", required: true, maxlength: 200, value: list?.title || autoTitle(state.size, catByKey[state.category]) });
  title.addEventListener("input", () => { titleTouched = true; });
  const syncTitle = () => { if (!titleTouched) title.value = autoTitle(state.size, catByKey[state.category]); };

  const lockedCat = editing && list.itemCount > 0;
  const catPicker = h("div", { class: "cat-picker", role: "radiogroup", "aria-label": "Category" },
    categories.map((c) => h("label", { class: "cat-option" },
      h("input", {
        type: "radio", name: "category", value: c.key, checked: c.key === state.category,
        disabled: lockedCat && c.key !== state.category,
        onchange: () => { state.category = c.key; syncTitle(); },
      }),
      h("span", {}, icon(c.icon), c.label),
    )),
  );

  const sizeInput = h("input", { type: "number", min: 1, max: limits.max, step: 1, value: state.size, inputmode: "numeric", style: { maxWidth: "140px" } });
  const hint = h("span", { class: "field-hint" });
  const chips = h("div", { class: "size-chips" });
  const renderSize = () => {
    const { text, cls } = sizeHint(state.size, limits);
    hint.textContent = text;
    hint.className = "field-hint " + cls;
    chips.replaceChildren(...SIZE_PRESETS.map((n) => h("button", {
      type: "button", "aria-pressed": String(n === state.size),
      onclick: () => { state.size = n; sizeInput.value = n; renderSize(); syncTitle(); },
    }, `Top ${n}`)));
  };
  sizeInput.addEventListener("input", () => { state.size = Number(sizeInput.value); renderSize(); syncTitle(); });
  renderSize();

  const desc = h("textarea", { name: "description", rows: 2, maxlength: 1000, placeholder: "Optional: a line about what makes this list", value: list?.description || "" });
  const slug = editing && h("input", { name: "slug", value: list.slug, maxlength: 60, pattern: "[a-z0-9-]+", spellcheck: false });
  const layout = list?.layout || "grid";
  const layoutGroup = h("div", { class: "radio-cards" },
    h("label", {}, h("input", { type: "radio", name: "layout", value: "grid", checked: layout === "grid" }), icon("grid"), "Artwork grid"),
    h("label", {}, h("input", { type: "radio", name: "layout", value: "rows", checked: layout === "rows" }), icon("rows"), "Ranked list"),
  );
  const visible = h("input", { type: "checkbox", name: "visible", checked: list ? list.visible : true });
  const error = h("p", { class: "alert alert--error", role: "alert", hidden: true });
  const save = h("button", { type: "submit", class: "btn btn--primary" }, editing ? "Save changes" : "Create list");

  let dlg;
  const form = h("form", { novalidate: true },
    dialogHead(editing ? "List settings" : "New list", () => dlg),
    h("div", { class: "dialog-body stack" },
      h("div", { class: "field" }, h("span", { class: "field-label" }, "Category"), catPicker,
        lockedCat && h("span", { class: "field-hint" }, "The category can't change once a list has entries.")),
      h("div", { class: "field" }, h("span", { class: "field-label" }, "How many?"),
        h("div", { class: "input-group", style: { alignItems: "center", flexWrap: "wrap" } }, chips, sizeInput), hint),
      h("label", { class: "field" }, h("span", { class: "field-label" }, "Title"), title),
      h("label", { class: "field" }, h("span", { class: "field-label" }, "Description"), desc),
      editing && h("label", { class: "field" }, h("span", { class: "field-label" }, "Address"),
        h("div", { class: "input-group", style: { alignItems: "center" } }, h("span", { class: "muted" }, "/l/"), slug)),
      h("div", { class: "field" }, h("span", { class: "field-label" }, "Layout"), layoutGroup),
      h("label", { class: "check" }, visible, "Show this list on my public page"),
      error,
    ),
    h("div", { class: "dialog-foot" },
      h("button", { type: "button", class: "btn", onclick: () => dlg.close() }, "Cancel"),
      save,
    ),
  );

  form.addEventListener("submit", async (e) => {
    e.preventDefault();
    error.hidden = true;
    const n = Number(sizeInput.value);
    if (!Number.isInteger(n) || n < 1 || n > limits.max) {
      error.hidden = false;
      error.textContent = sizeHint(n, limits).text;
      return;
    }
    const body = {
      title: title.value,
      category: state.category,
      maxItems: n,
      description: desc.value,
      layout: form.querySelector("input[name=layout]:checked").value,
      visible: visible.checked,
    };
    if (editing) body.slug = slug.value;
    busy(save, true);
    try {
      const saved = editing
        ? await api("PUT", `/api/lists/${list.id}`, body)
        : await api("POST", "/api/lists", body);
      dlg.close();
      onSaved(saved);
    } catch (err) {
      error.hidden = false;
      error.textContent = err.message;
    } finally {
      busy(save, false);
    }
  });

  dlg = openDialog(form);
  (editing ? title : catPicker.querySelector("input:checked"))?.focus();
  return dlg;
}