"use client";

import { Area, AreaChart, CartesianGrid, XAxis, YAxis } from "recharts";
import { ChartContainer, ChartTooltip, ChartTooltipContent, type ChartConfig } from "@/components/ui/chart";

export interface TimelineRow {
  bucket: number;
  sessionDeviceId: number;
  slotLabel: string;
  avgValue: number;
  maxValue: number;
}

const SERIES_COLORS = ["var(--chart-1)", "var(--chart-2)", "var(--chart-3)", "var(--chart-4)", "var(--chart-5)"];

// Chart config keys become raw CSS custom-property names (--color-<key>), so
// they must be safe identifiers - a user-chosen device display name isn't.
// Use the numeric session_device_id as the key, slotLabel only as display text.
function seriesKey(sessionDeviceId: number): string {
  return `device_${sessionDeviceId}`;
}

export function SessionTimelineChart({ timeline }: { timeline: TimelineRow[] }) {
  const series = [...new Map(timeline.map((r) => [r.sessionDeviceId, r.slotLabel])).entries()];
  const buckets = [...new Set(timeline.map((r) => r.bucket))].sort((a, b) => a - b);

  const data = buckets.map((bucket) => {
    const row: Record<string, number> = { bucket };
    for (const [sessionDeviceId] of series) {
      const match = timeline.find((r) => r.bucket === bucket && r.sessionDeviceId === sessionDeviceId);
      row[seriesKey(sessionDeviceId)] = match ? Math.round(match.avgValue * 100) : 0;
    }
    return row;
  });

  const config: ChartConfig = Object.fromEntries(
    series.map(([sessionDeviceId, slotLabel], i) => [
      seriesKey(sessionDeviceId),
      { label: slotLabel, color: SERIES_COLORS[i % SERIES_COLORS.length] },
    ]),
  );

  if (timeline.length === 0) {
    return <p className="text-sm text-muted-foreground">No device activity recorded for this session.</p>;
  }

  return (
    <ChartContainer config={config} className="h-64 w-full">
      <AreaChart data={data}>
        <defs>
          {series.map(([sessionDeviceId]) => (
            <linearGradient key={sessionDeviceId} id={`fill-${seriesKey(sessionDeviceId)}`} x1="0" y1="0" x2="0" y2="1">
              <stop offset="5%" stopColor={`var(--color-${seriesKey(sessionDeviceId)})`} stopOpacity={0.5} />
              <stop offset="95%" stopColor={`var(--color-${seriesKey(sessionDeviceId)})`} stopOpacity={0.03} />
            </linearGradient>
          ))}
        </defs>
        <CartesianGrid vertical={false} stroke="var(--border)" />
        <XAxis
          dataKey="bucket"
          tickFormatter={(v: number) => `${Math.round(v / 1000)}s`}
          tickLine={false}
          axisLine={false}
          className="bp-readout text-xs"
        />
        <YAxis domain={[0, 100]} tickLine={false} axisLine={false} width={32} className="bp-readout text-xs" />
        <ChartTooltip content={<ChartTooltipContent />} />
        {series.map(([sessionDeviceId]) => (
          <Area
            key={sessionDeviceId}
            type="monotone"
            dataKey={seriesKey(sessionDeviceId)}
            stroke={`var(--color-${seriesKey(sessionDeviceId)})`}
            strokeWidth={2}
            fill={`url(#fill-${seriesKey(sessionDeviceId)})`}
          />
        ))}
      </AreaChart>
    </ChartContainer>
  );
}