import { useLayoutEffect, useMemo, useRef, useState } from "react";
import { Icon } from "../../../components/Icon.jsx";

function calculateExpression(expression) {
  const normalized = String(expression || "").replaceAll(",", ".").trim();
  if (!normalized || !/^[\d\s+\-*/().]+$/.test(normalized)) return null;

  try {
    const value = Function(`"use strict"; return (${normalized})`)();
    return Number.isFinite(value) ? value : null;
  } catch {
    return null;
  }
}

function formatResult(value) {
  if (!Number.isFinite(value)) return "";
  return Number.parseFloat(value.toFixed(6)).toString();
}

function getChildren(entries, parentId) {
  return entries.filter((entry) => (entry.parentId || "") === parentId);
}

function getDescendantIds(entries, parentId) {
  const children = getChildren(entries, parentId);
  return children.flatMap((child) => [child.id, ...getDescendantIds(entries, child.id)]);
}

function getEntriesInTreeOrder(entries, parentId = "") {
  return getChildren(entries, parentId).flatMap((entry) => [entry, ...getEntriesInTreeOrder(entries, entry.id)]);
}

export function CalculatorModule({ toolboxId, moduleId, context }) {
  const data = context.normalizeCalculatorData(context.getModuleData(toolboxId, moduleId, { entries: [] }));
  const textContent = context.moduleText?.calculator || {};
  const [expression, setExpression] = useState("");
  const [label, setLabel] = useState("");
  const [activeParentId, setActiveParentId] = useState("");
  const [calculatorHeight, setCalculatorHeight] = useState(0);
  const [copied, setCopied] = useState(false);
  const calculatorCardRef = useRef(null);
  const result = useMemo(() => calculateExpression(expression), [expression]);
  const activeParent = data.entries.find((entry) => entry.id === activeParentId);

  useLayoutEffect(() => {
    const element = calculatorCardRef.current;
    if (!element) return undefined;

    function updateHeight() {
      setCalculatorHeight(Math.ceil(element.getBoundingClientRect().height));
    }

    updateHeight();
    const observer = new ResizeObserver(updateHeight);
    observer.observe(element);
    return () => observer.disconnect();
  }, []);

  function save(entries) {
    context.setModuleData(toolboxId, moduleId, { ...data, entries });
  }

  function setScrollResults(scrollResults) {
    context.setModuleData(toolboxId, moduleId, { ...data, scrollResults });
  }

  function saveResult(event) {
    event.preventDefault();
    if (result == null) return;
    const cleanLabel = label.trim();

    save([
      ...data.entries,
      {
        id: context.uid("calc"),
        parentId: activeParentId,
        label: cleanLabel,
        value: result
      }
    ]);
    setExpression("");
    setLabel("");
  }

  function useEntry(entry) {
    setExpression(formatResult(entry.value));
    setActiveParentId(entry.id);
  }

  function deleteEntry(entryId) {
    const deletedIds = new Set([entryId, ...getDescendantIds(data.entries, entryId)]);
    if (deletedIds.has(activeParentId)) setActiveParentId("");
    save(data.entries.filter((entry) => !deletedIds.has(entry.id)));
  }

  function renameEntry(entryId, label) {
    const cleanLabel = label.trim();
    save(data.entries.map((entry) => entry.id === entryId ? { ...entry, label: cleanLabel } : entry));
  }

  function resetCalculator() {
    setExpression("");
    setLabel("");
    setActiveParentId("");
  }

  async function copyChecklistImport() {
    const text = getEntriesInTreeOrder(data.entries)
      .map((entry) => `${entry.label || formatResult(entry.value)}:${formatResult(entry.value)}`)
      .join("\n");
    if (!text || !await context.copyText(text)) return;
    setCopied(true);
    window.setTimeout(() => setCopied(false), 1400);
  }

  return (
    <div className="calculator-module">
      <form className="calculator-form" onSubmit={saveResult}>
        <div className="calculator-card" ref={calculatorCardRef}>
          <label>
            <span>Calcul</span>
            <input value={expression} onChange={(event) => setExpression(event.target.value)} placeholder={textContent.expressionPlaceholder || "10*10"} inputMode="decimal" />
          </label>
          <div className="calculator-result" aria-live="polite">
            <span>Résultat</span>
            <strong>{result == null ? "-" : formatResult(result)}</strong>
          </div>
          <label>
            <span>Libellé</span>
            <input value={label} onChange={(event) => setLabel(event.target.value)} placeholder={textContent.labelPlaceholder || "Lingots de fer"} />
          </label>
          <button className="primary" disabled={result == null}>Enregistrer</button>
        </div>
      </form>
      <div
        className={`calculator-saved ${data.scrollResults ? "is-scrollable" : ""}`}
        style={data.scrollResults && calculatorHeight ? { "--calculator-scroll-height": `${calculatorHeight}px` } : undefined}
      >
        <div className="calculator-result-actions">
          {activeParent && (
            <button className="calculator-root-button" type="button" onClick={() => setActiveParentId("")}>
              Revenir à la racine
            </button>
          )}
          <button className="calculator-action-button danger" type="button" onClick={resetCalculator} aria-label="Réinitialiser le calculateur" title="Réinitialiser">
            <Icon name="rubber" />
          </button>
          <button className="calculator-action-button" type="button" onClick={copyChecklistImport} disabled={!data.entries.length} aria-label="Copier pour checklist" title={copied ? "Copié" : "Copier pour checklist"}>
            <Icon name="copy" />
          </button>
          <button
            className={`calculator-scroll-toggle ${data.scrollResults ? "active" : ""}`}
            type="button"
            onClick={() => setScrollResults(!data.scrollResults)}
            aria-pressed={data.scrollResults}
            title={textContent.scrollableTitle || "Liste scrollable"}
            aria-label={textContent.scrollableTitle || "Liste scrollable"}
          >
            <Icon name="scrollable" />
            <i aria-hidden="true" />
          </button>
        </div>
        <div className={`calculator-tree ${data.scrollResults ? "is-scrollable legacy-scrollbar" : ""}`}>
          {data.entries.length ? (
            <CalculatorEntries entries={data.entries} parentId="" activeParentId={activeParentId} onUse={useEntry} onRename={renameEntry} onDelete={deleteEntry} />
          ) : (
            <p className="muted">Aucun résultat enregistré.</p>
          )}
        </div>
      </div>
    </div>
  );
}

function CalculatorEntries({ entries, parentId, activeParentId, onUse, onRename, onDelete }) {
  const children = getChildren(entries, parentId);
  const [editingId, setEditingId] = useState("");
  if (!children.length) return null;

  return (
    <ul className="calculator-entry-list">
      {children.map((entry) => (
        <li className={`${entry.id === activeParentId ? "active" : ""} ${entry.id === editingId ? "is-editing" : ""}`} key={entry.id}>
          <div className="calculator-entry">
            {entry.id === editingId ? (
              <>
                <span className="calculator-entry-value is-readonly" title="Quantité non modifiable">
                  <strong>{formatResult(entry.value)}</strong>
                </span>
                <EditableCalculatorLabel entry={entry} onRename={onRename} onDone={() => setEditingId("")} />
              </>
            ) : (
              <button className="calculator-entry-summary" type="button" onClick={() => onUse(entry)} title="Utiliser comme base">
                <span><strong>{formatResult(entry.value)}</strong> {entry.label}</span>
              </button>
            )}
            <button type="button" onClick={() => setEditingId(entry.id === editingId ? "" : entry.id)} aria-label={`Renommer ${entry.label}`} title="Renommer">
              <Icon name="edit" />
            </button>
            <button type="button" className="danger" onClick={() => onDelete(entry.id)} aria-label={`Supprimer ${entry.label}`} title="Supprimer">
              <Icon name="trash" />
            </button>
          </div>
          <CalculatorEntries entries={entries} parentId={entry.id} activeParentId={activeParentId} onUse={onUse} onRename={onRename} onDelete={onDelete} />
        </li>
      ))}
    </ul>
  );
}

function EditableCalculatorLabel({ entry, onRename, onDone }) {
  const [label, setLabel] = useState(entry.label);
  const inputRef = useRef(null);

  useLayoutEffect(() => {
    inputRef.current?.focus();
  }, [entry.id]);

  function saveLabel() {
    const cleanLabel = label.trim();
    if (cleanLabel !== entry.label) onRename(entry.id, cleanLabel);
    onDone();
  }

  return (
    <input
      ref={inputRef}
      className="calculator-entry-label"
      value={label}
      onChange={(event) => setLabel(event.target.value)}
      onBlur={saveLabel}
      onKeyDown={(event) => {
        if (event.key === "Enter") event.currentTarget.blur();
        if (event.key === "Escape") {
          setLabel(entry.label);
          onDone();
        }
      }}
      aria-label={`Renommer ${entry.label}`}
    />
  );
}
