import { useState } from "react";
import {
	Cell,
	Label,
	Pie,
	PieChart,
	ResponsiveContainer,
	Tooltip,
} from "recharts";
import type { SetupItemWithCategory } from "../hooks/useSetups";
import { useWeightUnit } from "../hooks/useWeightUnit";
import { formatWeight, type WeightUnit } from "../lib/formatters";
import { LucideIcon } from "../lib/iconData";

const CATEGORY_COLORS = [
	"#374151",
	"#4b5563",
	"#6b7280",
	"#7f8a94",
	"#9ca3af",
	"#b0b7bf",
	"#c4c9cf",
	"#d1d5db",
	"#dfe2e6",
	"#e5e7eb",
];

const CLASSIFICATION_COLORS: Record<string, string> = {
	base: "#6b7280",
	worn: "#9ca3af",
	consumable: "#d1d5db",
};

const CLASSIFICATION_LABELS: Record<string, string> = {
	base: "Base Weight",
	worn: "Worn",
	consumable: "Consumable",
};

type ViewMode = "category" | "classification";
const VIEW_MODES: ViewMode[] = ["category", "classification"];

interface ChartDatum {
	name: string;
	weight: number;
	percent: number;
	classificationKey?: string;
}

interface WeightSummaryCardProps {
	items: SetupItemWithCategory[];
}

function buildCategoryChartData(items: SetupItemWithCategory[]): ChartDatum[] {
	const groups = new Map<string, number>();
	for (const item of items) {
		const current = groups.get(item.categoryName) ?? 0;
		groups.set(item.categoryName, current + (item.weightGrams ?? 0));
	}
	const total = items.reduce((sum, i) => sum + (i.weightGrams ?? 0), 0);
	return Array.from(groups.entries())
		.filter(([, weight]) => weight > 0)
		.map(([name, weight]) => ({
			name,
			weight,
			percent: total > 0 ? weight / total : 0,
		}));
}

function buildClassificationChartData(
	items: SetupItemWithCategory[],
): ChartDatum[] {
	const groups: Record<string, number> = {
		base: 0,
		worn: 0,
		consumable: 0,
	};
	for (const item of items) {
		groups[item.classification] += item.weightGrams ?? 0;
	}
	const total = Object.values(groups).reduce((a, b) => a + b, 0);
	return Object.entries(groups)
		.filter(([, weight]) => weight > 0)
		.map(([key, weight]) => ({
			name: CLASSIFICATION_LABELS[key] ?? key,
			weight,
			percent: total > 0 ? weight / total : 0,
			classificationKey: key,
		}));
}

function CustomTooltip({
	active,
	payload,
	unit,
}: {
	active?: boolean;
	payload?: Array<{ payload: ChartDatum }>;
	unit: WeightUnit;
}) {
	if (!active || !payload?.length) return null;
	const { name, weight, percent } = payload[0].payload;
	return (
		<div className="bg-white border border-gray-200 rounded-lg shadow-lg px-3 py-2 text-sm">
			<p className="font-medium text-gray-900">{name}</p>
			<p className="text-gray-600">
				{formatWeight(weight, unit)} ({(percent * 100).toFixed(1)}%)
			</p>
		</div>
	);
}

function LegendRow({
	color,
	label,
	weight,
	unit,
	percent,
}: {
	color: string;
	label: string;
	weight: number;
	unit: WeightUnit;
	percent?: number;
}) {
	return (
		<div className="flex items-center gap-3 py-1.5">
			<span
				className="w-2.5 h-2.5 rounded-full shrink-0"
				style={{ backgroundColor: color }}
			/>
			<span className="text-sm text-gray-600 flex-1">{label}</span>
			<span className="text-sm font-semibold text-gray-900 tabular-nums">
				{formatWeight(weight, unit)}
			</span>
			{percent != null && (
				<span className="text-xs text-gray-400 w-10 text-right tabular-nums">
					{(percent * 100).toFixed(0)}%
				</span>
			)}
		</div>
	);
}

export function WeightSummaryCard({ items }: WeightSummaryCardProps) {
	const unit = useWeightUnit();
	const [viewMode, setViewMode] = useState<ViewMode>("category");

	const baseWeight = items.reduce(
		(sum, i) =>
			i.classification === "base" ? sum + (i.weightGrams ?? 0) : sum,
		0,
	);
	const wornWeight = items.reduce(
		(sum, i) =>
			i.classification === "worn" ? sum + (i.weightGrams ?? 0) : sum,
		0,
	);
	const consumableWeight = items.reduce(
		(sum, i) =>
			i.classification === "consumable" ? sum + (i.weightGrams ?? 0) : sum,
		0,
	);
	const totalWeight = baseWeight + wornWeight + consumableWeight;

	const chartData =
		viewMode === "category"
			? buildCategoryChartData(items)
			: buildClassificationChartData(items);

	const colors =
		viewMode === "category"
			? CATEGORY_COLORS
			: chartData.map(
					(d) => CLASSIFICATION_COLORS[d.classificationKey ?? ""] ?? "#6366f1",
				);

	if (totalWeight === 0) {
		return (
			<div className="bg-white rounded-xl border border-gray-100 p-5 mb-6">
				<h3 className="text-sm font-medium text-gray-700 mb-2">
					Weight Summary
				</h3>
				<p className="text-sm text-gray-400">No weight data to display</p>
			</div>
		);
	}

	return (
		<div className="bg-white rounded-xl border border-gray-100 p-5 mb-6">
			{/* Header with pill toggle */}
			<div className="flex items-center justify-between mb-4">
				<h3 className="text-sm font-medium text-gray-700">Weight Summary</h3>
				<div className="flex items-center gap-1 bg-gray-100 rounded-full px-1 py-0.5">
					{VIEW_MODES.map((mode) => (
						<button
							key={mode}
							type="button"
							onClick={() => setViewMode(mode)}
							className={`px-2.5 py-0.5 text-xs rounded-full transition-colors ${
								viewMode === mode
									? "bg-white text-gray-700 shadow-sm font-medium"
									: "text-gray-400 hover:text-gray-600"
							}`}
						>
							{mode === "category" ? "Category" : "Classification"}
						</button>
					))}
				</div>
			</div>

			{/* Main content: chart + subtotals side by side */}
			<div className="flex items-center gap-8">
				{/* Donut chart */}
				<div className="flex-shrink-0" style={{ width: 180, height: 180 }}>
					<ResponsiveContainer width="100%" height={180}>
						<PieChart>
							<Pie
								data={chartData}
								dataKey="weight"
								nameKey="name"
								cx="50%"
								cy="50%"
								innerRadius={55}
								outerRadius={80}
								paddingAngle={2}
							>
								{chartData.map((entry, index) => (
									<Cell key={entry.name} fill={colors[index % colors.length]} />
								))}
								<Label
									value={formatWeight(totalWeight, unit)}
									position="center"
									style={{
										fontSize: "14px",
										fontWeight: 600,
										fill: "#374151",
									}}
								/>
							</Pie>
							<Tooltip content={<CustomTooltip unit={unit} />} />
						</PieChart>
					</ResponsiveContainer>
				</div>

				{/* Weight legend */}
				<div className="flex-1 flex flex-col justify-center min-w-0">
					<LegendRow
						color="#6b7280"
						label="Base Weight"
						weight={baseWeight}
						unit={unit}
						percent={totalWeight > 0 ? baseWeight / totalWeight : undefined}
					/>
					<LegendRow
						color="#9ca3af"
						label="Worn"
						weight={wornWeight}
						unit={unit}
						percent={totalWeight > 0 ? wornWeight / totalWeight : undefined}
					/>
					<LegendRow
						color="#d1d5db"
						label="Consumable"
						weight={consumableWeight}
						unit={unit}
						percent={totalWeight > 0 ? consumableWeight / totalWeight : undefined}
					/>
					<div className="border-t border-gray-200 mt-1.5 pt-1.5">
						<div className="flex items-center gap-3 py-1.5">
							<LucideIcon name="sigma" size={10} className="text-gray-400 shrink-0 ml-0.5" />
							<span className="text-sm font-medium text-gray-700 flex-1">Total</span>
							<span className="text-sm font-bold text-gray-900 tabular-nums">
								{formatWeight(totalWeight, unit)}
							</span>
							<span className="w-10" />
						</div>
					</div>
				</div>
			</div>
		</div>
	);
}