import { Button } from "@code/ui/components/button";
import {
  ArrowUpRight,
  Bot,
  ExternalLink,
  FileText,
  GitPullRequest,
  Layers,
  Radio,
  TriangleAlert,
} from "lucide-react";

import { formatRelativeTime } from "@/lib/work-os/work-unit-projection";
import type { WorkUnitDetail as WorkUnitDetailData } from "@/lib/work-os/work-unit-projection";

const formatStatus = (
  status: WorkUnitDetailData["issue"]["status"]
): string => {
  if (status === "needs-input") {
    return "Needs input";
  }
  if (status === "working") {
    return "In progress";
  }
  return status.charAt(0).toUpperCase() + status.slice(1);
};

interface WorkUnitDetailProps {
  readonly detail: WorkUnitDetailData;
  readonly onOpenPullRequest: (url: string) => void;
  readonly onStart: () => void;
  readonly startPending: boolean;
}

const Section = ({
  children,
  icon,
  title,
}: {
  readonly children: React.ReactNode;
  readonly icon: React.ReactNode;
  readonly title: string;
}) => (
  <section className="rounded-2xl border border-border/30 bg-card/30 p-4">
    <div className="mb-3 flex items-center gap-2 text-[11px] font-semibold uppercase tracking-wider text-muted-foreground">
      {icon}
      {title}
    </div>
    {children}
  </section>
);

export const WorkUnitDetail = ({
  detail,
  onOpenPullRequest,
  onStart,
  startPending,
}: WorkUnitDetailProps) => {
  const { issue } = detail;
  const canStart = issue.status === "open" || issue.status === "failed";

  return (
    <div className="space-y-4">
      {/* Objective */}
      <section className="rounded-2xl border border-border/40 bg-card/40 p-5">
        <div className="flex items-start justify-between gap-3">
          <div className="min-w-0">
            <p className="text-[11px] font-medium text-muted-foreground">
              Work Unit #{issue.number}
            </p>
            <h2 className="mt-1 text-lg font-semibold leading-7 tracking-tight">
              {issue.title}
            </h2>
          </div>
          <span className="shrink-0 rounded-full bg-muted px-2.5 py-1 text-[11px] font-medium">
            {formatStatus(issue.status)}
          </span>
        </div>
        <p className="mt-3 text-sm leading-6 text-muted-foreground">
          {issue.body}
        </p>
        {canStart ? (
          <Button
            className="mt-4 w-full"
            disabled={startPending}
            onClick={onStart}
            type="button"
          >
            <Bot className="size-4" />
            {startPending ? "Starting" : "Start work"}
          </Button>
        ) : null}
      </section>

      {/* Needs input alert */}
      {detail.needsInput ? (
        <div className="flex items-start gap-3 rounded-2xl border border-amber-500/30 bg-amber-500/10 p-4">
          <TriangleAlert className="mt-0.5 size-4 shrink-0 text-amber-400" />
          <div>
            <p className="text-sm font-medium text-amber-300">
              This work unit needs your input
            </p>
            <p className="mt-1 text-xs leading-5 text-amber-400/70">
              Resolve the open question or decision to unblock the agent.
            </p>
          </div>
        </div>
      ) : null}

      {/* Latest summary */}
      {detail.latestSummary ? (
        <Section icon={<ArrowUpRight className="size-3" />} title="Latest">
          <p className="text-sm leading-6">{detail.latestSummary}</p>
        </Section>
      ) : null}

      {/* Linked Signals — authenticated via signalIssueAttachments */}
      <Section
        icon={<Radio className="size-3" />}
        title={`Signals (${detail.signalCount})`}
      >
        {detail.linkedSignals.length > 0 ? (
          <div className="space-y-3">
            {detail.linkedSignals.map((signal) => (
              <div key={String(signal.signalId)}>
                <p className="text-sm font-medium">{signal.title}</p>
                <p className="mt-0.5 line-clamp-2 text-xs leading-5 text-muted-foreground">
                  {signal.summary}
                </p>
                <p className="mt-1 text-[10px] text-muted-foreground/60">
                  {signal.sourceCount} source
                  {signal.sourceCount === 1 ? "" : "s"} ·{" "}
                  {formatRelativeTime(signal.createdAt)}
                </p>
              </div>
            ))}
          </div>
        ) : (
          <p className="text-xs leading-5 text-muted-foreground">
            No Signals linked to this Work Unit.
          </p>
        )}
      </Section>

      {/* Activity timeline */}
      <Section
        icon={<Layers className="size-3" />}
        title={`Timeline (${detail.stepCount} steps)`}
      >
        {detail.activity.length > 0 ? (
          <div className="space-y-4">
            {detail.activity.map((item) => (
              <div
                className="flex gap-3"
                key={`${item.kind}-${item.createdAt}`}
              >
                <div className="mt-1.5 size-1.5 shrink-0 rounded-full bg-foreground/40" />
                <div className="min-w-0">
                  <p className="text-xs font-medium">{item.label}</p>
                  <p className="mt-0.5 text-xs leading-5 text-muted-foreground">
                    {item.detail}
                  </p>
                  <p className="mt-0.5 text-[10px] text-muted-foreground/60">
                    {item.time}
                  </p>
                </div>
              </div>
            ))}
          </div>
        ) : (
          <p className="text-xs text-muted-foreground">
            No activity recorded yet.
          </p>
        )}
      </Section>

      {/* Artifacts */}
      <Section
        icon={<FileText className="size-3" />}
        title={`Artifacts (${detail.artifactCount})`}
      >
        {detail.artifactPaths.length > 0 ? (
          <div className="flex flex-wrap gap-2">
            {detail.artifactPaths.map((path) => (
              <span
                className="inline-flex items-center gap-1.5 rounded-lg bg-muted/60 px-2.5 py-1 text-[11px]"
                key={path}
              >
                <FileText className="size-3 text-muted-foreground" />
                {path}
              </span>
            ))}
          </div>
        ) : (
          <p className="text-xs text-muted-foreground">
            No artifacts produced yet.
          </p>
        )}
      </Section>

      {/* Pull request */}
      {detail.hasPullRequest ? (
        <Section
          icon={<GitPullRequest className="size-3" />}
          title="Pull request"
        >
          {detail.pullRequestUrl ? (
            <div className="rounded-xl border border-emerald-500/20 bg-emerald-500/5 p-3">
              <p className="text-sm font-medium text-emerald-300">
                {detail.pullRequestNumber
                  ? `PR #${detail.pullRequestNumber} ready for review`
                  : "Pull request ready"}
              </p>
              <Button
                className="mt-3"
                onClick={() =>
                  detail.pullRequestUrl &&
                  onOpenPullRequest(detail.pullRequestUrl)
                }
                size="sm"
                type="button"
                variant="outline"
              >
                <ExternalLink className="size-3.5" />
                Review changes
              </Button>
            </div>
          ) : (
            <p className="text-xs text-muted-foreground">
              A pull request was opened but the URL is unavailable.
            </p>
          )}
        </Section>
      ) : null}
    </div>
  );
};