import { useState, useRef, useCallback } from "react";
import { useTranslation } from "react-i18next";
import {
  BarChart,
  Bar,
  AreaChart,
  Area,
  XAxis,
  YAxis,
  Tooltip,
  ResponsiveContainer,
  Legend,
  CartesianGrid,
  LabelList,
} from "recharts";
import { Eye } from "lucide-react";
import type { CategoryOverTimeData, CategoryBreakdownItem } from "../../shared/types";
import { ChartPatternDefs, getPatternFill } from "../../utils/chartPatterns";
import ChartContextMenu from "../shared/ChartContextMenu";

const cadFormatter = (value: number) =>
  new Intl.NumberFormat("en-CA", { style: "currency", currency: "CAD", maximumFractionDigits: 0 }).format(value);

function formatMonth(month: string): string {
  const [year, m] = month.split("-");
  const date = new Date(Number(year), Number(m) - 1);
  return date.toLocaleDateString("default", { month: "short", year: "2-digit" });
}

export type CategoryOverTimeChartType = "line" | "area";

interface CategoryOverTimeChartProps {
  data: CategoryOverTimeData;
  hiddenCategories: Set<string>;
  onToggleHidden: (categoryName: string) => void;
  onShowAll: () => void;
  onViewDetails: (item: CategoryBreakdownItem) => void;
  showAmounts?: boolean;
  /**
   * Visual rendering mode. `line` (default) keeps the legacy stacked bars —
   * preserved for backward compatibility. `area` stacks Recharts <Area> layers
   * (stackId="1") showing total composition over time. Both modes share the
   * same palette and SVG grayscale patterns (existing signature visual).
   */
  chartType?: CategoryOverTimeChartType;
}

export default function CategoryOverTimeChart({
  data,
  hiddenCategories,
  onToggleHidden,
  onShowAll,
  onViewDetails,
  showAmounts,
  chartType = "line",
}: CategoryOverTimeChartProps) {
  const { t } = useTranslation();
  const hoveredRef = useRef<string | null>(null);
  const [hoveredCategory, setHoveredCategory] = useState<string | null>(null);
  const [contextMenu, setContextMenu] = useState<{ x: number; y: number; name: string } | null>(null);

  const visibleCategories = data.categories.filter((name) => !hiddenCategories.has(name));
  const categoryEntries = visibleCategories.map((name, index) => ({
    name,
    color: data.colors[name],
    index,
  }));

  const handleContextMenu = useCallback((e: React.MouseEvent) => {
    if (!hoveredRef.current) return;
    e.preventDefault();
    setContextMenu({ x: e.clientX, y: e.clientY, name: hoveredRef.current });
  }, []);

  if (data.data.length === 0) {
    return (
      <div className="bg-[var(--card)] rounded-xl p-6 border border-[var(--border)]">
        <p className="text-center text-[var(--muted-foreground)] py-8">{t("dashboard.noData")}</p>
      </div>
    );
  }

  // Shared chart configuration used by both Bar and Area variants.
  const patternPrefix = "cat-time";
  const patternDefs = (
    <ChartPatternDefs
      prefix={patternPrefix}
      categories={categoryEntries.map((c) => ({ color: c.color, index: c.index }))}
    />
  );
  const commonAxes = (
    <>
      <CartesianGrid strokeDasharray="3 3" stroke="var(--border)" />
      <XAxis
        dataKey="month"
        tickFormatter={formatMonth}
        tick={{ fill: "var(--muted-foreground)", fontSize: 12 }}
        stroke="var(--border)"
      />
      <YAxis
        tickFormatter={(v) => cadFormatter(v)}
        tick={{ fill: "var(--muted-foreground)", fontSize: 12 }}
        stroke="var(--border)"
        width={80}
      />
      <Tooltip
        formatter={(value: unknown, name: unknown) => {
          if (hoveredCategory && name !== hoveredCategory) return [null, null];
          return [cadFormatter(Number(value) || 0), String(name)];
        }}
        labelFormatter={(label) => formatMonth(String(label))}
        contentStyle={{
          backgroundColor: "var(--card)",
          border: "1px solid var(--border)",
          borderRadius: "8px",
          color: "var(--foreground)",
          boxShadow: "0 4px 12px rgba(0,0,0,0.15)",
        }}
        wrapperStyle={{ zIndex: 50 }}
        labelStyle={{ color: "var(--foreground)" }}
        itemStyle={{ color: "var(--foreground)" }}
        filterNull
      />
      <Legend
        onMouseEnter={(e) => {
          if (e && e.dataKey) setHoveredCategory(String(e.dataKey));
        }}
        onMouseLeave={() => setHoveredCategory(null)}
        wrapperStyle={{ cursor: "pointer" }}
        formatter={(value) => <span style={{ color: "var(--foreground)" }}>{value}</span>}
      />
    </>
  );

  return (
    <div className="bg-[var(--card)] rounded-xl p-6 border border-[var(--border)]">
      {hiddenCategories.size > 0 && (
        <div className="flex flex-wrap items-center gap-2 mb-4">
          <span className="text-xs text-[var(--muted-foreground)]">{t("charts.hiddenCategories")}:</span>
          {Array.from(hiddenCategories).map((name) => (
            <button
              key={name}
              onClick={() => onToggleHidden(name)}
              className="inline-flex items-center gap-1 px-2 py-0.5 text-xs rounded-full bg-[var(--muted)] text-[var(--muted-foreground)] hover:bg-[var(--border)] transition-colors"
            >
              <Eye size={12} />
              {name}
            </button>
          ))}
          <button
            onClick={onShowAll}
            className="text-xs text-[var(--primary)] hover:underline"
          >
            {t("charts.showAll")}
          </button>
        </div>
      )}

      <div onContextMenu={handleContextMenu}>
        <ResponsiveContainer width="100%" height={400}>
          {chartType === "area" ? (
            <AreaChart data={data.data} margin={{ top: 10, right: 10, left: 10, bottom: 0 }}>
              {patternDefs}
              {commonAxes}
              {categoryEntries.map((c) => (
                <Area
                  key={c.name}
                  type="monotone"
                  dataKey={c.name}
                  stackId="1"
                  stroke={c.color}
                  fill={getPatternFill(patternPrefix, c.index, c.color)}
                  fillOpacity={hoveredCategory === null || hoveredCategory === c.name ? 1 : 0.2}
                  onMouseEnter={() => { hoveredRef.current = c.name; setHoveredCategory(c.name); }}
                  onMouseLeave={() => { hoveredRef.current = null; setHoveredCategory(null); }}
                  style={{ transition: "fill-opacity 150ms", cursor: "context-menu" }}
                />
              ))}
            </AreaChart>
          ) : (
            <BarChart data={data.data} margin={{ top: 10, right: 10, left: 10, bottom: 0 }}>
              {patternDefs}
              {commonAxes}
              {categoryEntries.map((c) => (
                <Bar
                  key={c.name}
                  dataKey={c.name}
                  stackId="stack"
                  fill={getPatternFill(patternPrefix, c.index, c.color)}
                  fillOpacity={hoveredCategory === null || hoveredCategory === c.name ? 1 : 0.2}
                  onMouseEnter={() => { hoveredRef.current = c.name; setHoveredCategory(c.name); }}
                  onMouseLeave={() => { hoveredRef.current = null; setHoveredCategory(null); }}
                  cursor="context-menu"
                  style={{ transition: "fill-opacity 150ms" }}
                >
                  {showAmounts && (
                    <LabelList
                      dataKey={c.name}
                      position="center"
                      formatter={(v: unknown) => Number(v) ? cadFormatter(Number(v)) : ""}
                      style={{ fill: "#000", fontSize: 10, fontWeight: 600, paintOrder: "stroke", stroke: "rgba(255,255,255,0.7)", strokeWidth: 3, strokeLinejoin: "round" }}
                    />
                  )}
                </Bar>
              ))}
            </BarChart>
          )}
        </ResponsiveContainer>
      </div>

      {contextMenu && (
        <ChartContextMenu
          x={contextMenu.x}
          y={contextMenu.y}
          categoryName={contextMenu.name}
          onHide={() => onToggleHidden(contextMenu.name)}
          onViewDetails={() => {
            const color = data.colors[contextMenu.name] || "#9ca3af";
            const categoryId = data.categoryIds[contextMenu.name] ?? null;
            onViewDetails({
              category_id: categoryId,
              category_name: contextMenu.name,
              category_color: color,
              total: 0,
            });
          }}
          onClose={() => setContextMenu(null)}
        />
      )}
    </div>
  );
}