import { useId } from "react";
import type { ReactNode } from "react";
import type { FlowGraph, FlowNode } from "../../lib/types";
import {
  FLOW_TONE,
  STATUS_ORDER,
  statusOf,
} from "./flow/tone";
import { layoutFlow, NODE_W, NODE_H, type FlowOrientation, type PlacedBand } from "./flow/layout";
import { edgeShapes, type EdgeShape } from "./flow/edges";

/** Lightweight SVG directed-graph renderer for a FlowGraph (no graph deps).
 *  A node's step is its longest-path depth from a root; the steps advance along the
 *  **time axis** and the newest one always sits at the canvas origin (top or left, see
 *  `FlowOrientation` in flow/layout.ts). Sub-agent branches are drawn in their own framed
 *  lanes beside the trunk (design/19 §2), so parallel branches read as separate swimlanes
 *  instead of interleaving. Edges are cubic beziers with an arrowhead anchored on the
 *  border the direction dictates (flow/edges.ts); node stroke/fill is coded by status and
 *  a running node pulses with the panel's existing `.mu-blink` (no new animation dep).
 *
 *  容器**不限高**：图多高就多高（主人要求「容器高度自动拓高」，不在内部裁切）；横向仅在
 *  泳道把画布撑宽时滚动（`newest-top` 下就是这种情形），纵向永远随图生长。 */

/** 方向提示（画在图例里）：让「哪端是最新」写在脸上，不靠用户自己猜。 */
const DIRECTION_HINT: Record<FlowOrientation, string> = {
  "newest-top": "时序自下而上 ↑ · 最新在最上",
  "newest-left": "时序自右向左 ← · 最新在最左",
};

export function FlowGraphView({
  graph,
  orientation,
  onNodeClick,
  selectedId,
}: {
  graph: FlowGraph;
  /** 渲染方向（flow/layout.ts）：`newest-top` = 时序自下而上（整页 Flow）；
   *  `newest-left` = 时序自右向左（嵌在页面里的图块，容器默认露出最左边）。 */
  orientation: FlowOrientation;
  onNodeClick?: (node: FlowNode) => void;
  selectedId?: string | null;
}): ReactNode {
  const markerId = useId().replace(/[^a-zA-Z0-9]/g, "");
  const laneMarkerId = `${markerId}L`;
  const layout = layoutFlow(graph, orientation);
  const { nodes, bands, lanes, width, height } = layout;
  const shapes = edgeShapes(layout);
  const laneRoots = new Set(lanes.map((l) => l.id));

  return (
    <div className="space-y-2">
      <div
        data-flow-canvas="1"
        className="overflow-x-auto rounded-[var(--mu-radius)] border border-[var(--mu-glass-border)] bg-[var(--mu-surface-2)] p-3"
      >
        <svg width={width} height={height} viewBox={`0 0 ${width} ${height}`} className="block">
          <defs>
            <marker
              id={markerId}
              viewBox="0 0 10 10"
              refX="9"
              refY="5"
              markerWidth="7"
              markerHeight="7"
              orient="auto-start-reverse"
            >
              <path d="M 0 0 L 10 5 L 0 10 z" fill="var(--mu-text-lo)" />
            </marker>
            <marker
              id={laneMarkerId}
              viewBox="0 0 10 10"
              refX="9"
              refY="5"
              markerWidth="7"
              markerHeight="7"
              orient="auto-start-reverse"
            >
              <path d="M 0 0 L 10 5 L 0 10 z" fill="var(--mu-accent)" />
            </marker>
          </defs>

          {bands.filter((b) => b.framed).map((band) => (
            <LaneFrame key={band.id} band={band} />
          ))}

          {shapes.map((shape, i) => (
            <EdgePath
              key={`${shape.fromId}-${shape.toId}-${i}`}
              shape={shape}
              markerId={markerId}
              laneMarkerId={laneMarkerId}
            />
          ))}

          {nodes.map((p) => (
            <NodeGroup
              key={p.node.id}
              node={p.node}
              x={p.x}
              y={p.y}
              selected={selectedId === p.node.id}
              lane={laneRoots.has(p.node.id)}
              onNodeClick={onNodeClick}
            />
          ))}
        </svg>
      </div>
      <Legend hasLanes={lanes.length > 0} orientation={orientation} />
    </div>
  );
}

/** EdgePath draws one cubic bezier between the two placed nodes; edges that run into
 *  a lane are dashed and accent-colored so the trunk stays readable. The endpoints come
 *  from `edgeShapes` — the component never recomputes (nor guesses) them. */
function EdgePath({
  shape,
  markerId,
  laneMarkerId,
}: {
  shape: EdgeShape;
  markerId: string;
  laneMarkerId: string;
}): ReactNode {
  return (
    <path
      d={shape.d}
      fill="none"
      stroke={shape.inLane ? "var(--mu-accent)" : "var(--mu-text-lo)"}
      strokeOpacity={shape.inLane ? 0.7 : 1}
      strokeWidth="1.5"
      strokeDasharray={shape.inLane ? "5 3" : undefined}
      markerEnd={`url(#${shape.inLane ? laneMarkerId : markerId})`}
    />
  );
}

/** LaneFrame draws one sub-agent swimlane container: a dashed Miuix surface with
 *  a header carrying the sub-agent label and its live status. */
function LaneFrame({ band }: { band: PlacedBand }): ReactNode {
  const tone = FLOW_TONE[band.status];
  const running = band.status === "running";
  return (
    <g>
      <rect
        x={band.x}
        y={band.y}
        width={band.width}
        height={band.height}
        rx="16"
        fill="color-mix(in srgb, var(--mu-accent) 5%, transparent)"
        stroke="var(--mu-glass-border)"
        strokeDasharray="6 4"
        strokeWidth="1"
      />
      <text
        x={band.x + 12}
        y={band.y + 15}
        fontSize="10"
        fill="var(--mu-text-mid)"
      >
        泳道 · {clampLabel(band.label, 24)}
      </text>
      <circle
        cx={band.x + band.width - 14}
        cy={band.y + 11}
        r="4"
        fill={tone.stroke}
        className={running ? "mu-blink" : undefined}
      />
    </g>
  );
}

/** NodeGroup draws one node card: a status-colored rounded rect plus kind/label
 *  text and a status dot. A running node carries a blinking halo so 运行中 is
 *  visible at a glance without animating the text. */
function NodeGroup({
  node,
  x,
  y,
  selected,
  lane,
  onNodeClick,
}: {
  node: FlowNode;
  x: number;
  y: number;
  selected: boolean;
  lane: boolean;
  onNodeClick?: (node: FlowNode) => void;
}): ReactNode {
  const status = statusOf(node);
  const tone = FLOW_TONE[status];
  return (
    <g
      onClick={onNodeClick ? () => onNodeClick(node) : undefined}
      className={onNodeClick ? "cursor-pointer" : undefined}
    >
      <title>{`${node.label} · ${tone.label}`}</title>
      {status === "running" ? (
        <rect
          x={x - 4}
          y={y - 4}
          width={NODE_W + 8}
          height={NODE_H + 8}
          rx="16"
          fill="none"
          stroke={tone.stroke}
          strokeWidth="2"
          className="mu-blink"
        />
      ) : null}
      <rect
        x={x}
        y={y}
        width={NODE_W}
        height={NODE_H}
        rx="12"
        fill={tone.fill}
        stroke={tone.stroke}
        strokeWidth={selected ? 3 : 1.5}
      />
      <circle cx={x + NODE_W - 12} cy={y + 11} r="3.5" fill={tone.stroke} />
      {lane ? (
        <text x={x + 10} y={y + 15} fontSize="9" fill="var(--mu-accent)">
          泳道根
        </text>
      ) : null}
      {node.kind ? (
        <text
          x={x + NODE_W / 2}
          y={y + 20}
          textAnchor="middle"
          fontSize="9"
          fill="var(--mu-text-lo)"
        >
          {node.kind}
        </text>
      ) : null}
      <text
        x={x + NODE_W / 2}
        y={y + (node.kind ? 41 : NODE_H / 2 + 5)}
        textAnchor="middle"
        fontSize="12"
        fontWeight="500"
        fill="var(--mu-text-hi)"
      >
        {clampLabel(node.label, 20)}
      </text>
    </g>
  );
}

/** Legend explains the status colors, the lane edge style, and which end of the time
 *  axis is the newest one (the direction is reversed for the whole-page view). */
function Legend({
  hasLanes,
  orientation,
}: {
  hasLanes: boolean;
  orientation: FlowOrientation;
}): ReactNode {
  return (
    <div className="flex flex-wrap items-center gap-3 px-1">
      {STATUS_ORDER.map((s) => (
        <span
          key={s}
          className="inline-flex items-center gap-1.5 text-[10px] text-[var(--mu-text-lo)]"
        >
          <span className="h-2 w-2 rounded-full" style={{ backgroundColor: FLOW_TONE[s].stroke }} />
          {FLOW_TONE[s].label}
        </span>
      ))}
      {hasLanes ? (
        <span className="inline-flex items-center gap-1.5 text-[10px] text-[var(--mu-text-lo)]">
          <svg width="22" height="8" aria-hidden="true">
            <line
              x1="0"
              y1="4"
              x2="22"
              y2="4"
              stroke="var(--mu-accent)"
              strokeWidth="1.5"
              strokeDasharray="5 3"
            />
          </svg>
          泳道内步骤
        </span>
      ) : null}
      <span className="inline-flex items-center gap-1.5 text-[10px] text-[var(--mu-text-lo)]">
        {DIRECTION_HINT[orientation]}
      </span>
    </div>
  );
}

/** clampLabel shortens a node label to fit the fixed-width node card. */
function clampLabel(label: string, max: number): string {
  return label.length > max ? `${label.slice(0, max - 1)}…` : label;
}