'use client';

import { useState } from 'react';
import Link from 'next/link';
import { api } from '@/lib/trpc';
import { SignedOut } from '@/components/chrome/signed-out';
import { buttonClasses, EmptyState, Segmented } from '@/components/ui';
import { JobRow, JobRowSkeleton, type JobRowData, type Perspective } from '@/components/jobs/job-row';
import { JobDetail } from '@/components/jobs/job-detail';
import { ChatThread } from '@/components/jobs/chat-thread';
import { ReviewSheet } from '@/components/jobs/review-sheet';
import { ReviewPrompt } from '@/components/jobs/review-prompt';

/**
 * Where you are inside the tab.
 *
 * `jobId` on a thread is where Back goes, not where the thread came from: a
 * client reaches a conversation through their job and should land back on it,
 * while a pro's list row IS the conversation and has no middle screen to return
 * to. Storing the destination rather than the history keeps Back from ever
 * needing a stack.
 */
export type JobsView =
  | { kind: 'list' }
  | { kind: 'job'; jobId: string }
  | { kind: 'thread'; matchId: string; jobId: string | null };

export type JobsSegment = 'current' | 'past';

export interface JobsState {
  view: JobsView;
  segment: JobsSegment;
}

export const INITIAL_JOBS_STATE: JobsState = { view: { kind: 'list' }, segment: 'current' };

/**
 * The Jobs tab.
 *
 * Current and past are one list under a segmented control rather than two tabs,
 * because they are the same objects at different points in their life — and
 * because a job moves between them on its own, without the user doing anything.
 * `isActive` comes from the server (ACTIVE_JOB_STATUSES), so the split cannot
 * drift from the state machine.
 *
 * State is owned by the parent for the reason SearchPanel's is: the tab bar
 * unmounts panels on switch, and losing your place in a half-read conversation
 * because you glanced at Settings is worse than losing a search query.
 */
export function JobsPanel({
  state,
  onChange,
}: {
  state: JobsState;
  onChange: (next: JobsState) => void;
}) {
  const me = api.user.me.useQuery(undefined, { retry: false });

  const go = (view: JobsView) => onChange({ ...state, view });

  if (me.isLoading) {
    return (
      <Shell>
        <div className="flex flex-col gap-3">
          <JobRowSkeleton />
          <JobRowSkeleton />
          <JobRowSkeleton />
        </div>
      </Shell>
    );
  }

  if (me.error || !me.data) {
    return (
      <SignedOut
        title="Sign in to see your jobs"
        body="Everything you have posted, and every conversation about it."
      />
    );
  }

  if (state.view.kind === 'thread') {
    const { matchId, jobId } = state.view;
    return (
      <ChatThread
        matchId={matchId}
        onBack={() => go(jobId ? { kind: 'job', jobId } : { kind: 'list' })}
      />
    );
  }

  if (state.view.kind === 'job') {
    const { jobId } = state.view;
    return (
      <JobDetail
        jobId={jobId}
        onBack={() => go({ kind: 'list' })}
        onOpenThread={(matchId) => go({ kind: 'thread', matchId, jobId })}
      />
    );
  }

  return me.data.role === 'pro' ? (
    <ProJobs state={state} onChange={onChange} />
  ) : (
    <ClientJobs state={state} onChange={onChange} />
  );
}

/**
 * Work that is finished and still owed a review, above the Past list.
 *
 * The reason the Past segment is worth opening. A rating is the only thing a new
 * pro has to trade on, and nobody navigates to a finished job to leave one
 * unprompted — so it is asked for where the finished job already is.
 */
function PendingReviews() {
  const pending = api.review.pending.useQuery(undefined, { retry: false });
  const [open, setOpen] = useState<{
    bookingId: string;
    subjectName: string;
    jobTitle: string;
  } | null>(null);

  const rows = pending.data ?? [];
  if (rows.length === 0) return null;

  return (
    <>
      <ul className="mb-4 flex flex-col gap-2">
        {rows.map((r) => (
          <li key={r.bookingId}>
            <ReviewPrompt
              subjectName={r.subjectName}
              jobTitle={r.jobTitle}
              onOpen={() =>
                setOpen({
                  bookingId: r.bookingId,
                  subjectName: r.subjectName,
                  jobTitle: r.jobTitle,
                })
              }
            />
          </li>
        ))}
      </ul>

      <ReviewSheet
        bookingId={open?.bookingId ?? null}
        subjectName={open?.subjectName ?? ''}
        jobTitle={open?.jobTitle ?? ''}
        open={open !== null}
        onClose={() => setOpen(null)}
      />
    </>
  );
}

function Shell({ children }: { children: React.ReactNode }) {
  return <div className="min-h-0 flex-1 overflow-y-auto px-4 pb-4 pt-[3.25rem]">{children}</div>;
}

/* ─────────────────────────────── client ─────────────────────────────── */

function ClientJobs({
  state,
  onChange,
}: {
  state: JobsState;
  onChange: (next: JobsState) => void;
}) {
  // Polled, not pushed: a job list that goes stale hides the one thing this tab
  // exists to surface — that somebody replied. Thirty seconds is cheap here and
  // the thread itself refreshes far faster while it is open.
  const jobs = api.job.mine.useQuery(undefined, { refetchInterval: 30_000 });

  const rows: JobRowData[] = (jobs.data ?? []).map((j) => ({
    id: j.id,
    title: j.title,
    status: j.status,
    subtitle: j.categoryName,
    createdAt: j.createdAt,
    matchCount: j.matchCount,
    pendingCount: j.pendingCount,
    unreadCount: j.unreadCount,
    lastMessageAt: j.lastMessageAt,
    nextBookingAt: j.nextBookingAt,
  }));
  const active = (jobs.data ?? []).filter((j) => j.isActive).map((j) => j.id);

  return (
    <JobList
      perspective="client"
      loading={jobs.isLoading}
      rows={rows}
      activeIds={new Set(active)}
      state={state}
      onChange={onChange}
      onOpen={(jobId) => onChange({ ...state, view: { kind: 'job', jobId } })}
      empty={{
        current: {
          title: 'No jobs on the go',
          body: 'Post a job and we will build you a deck of verified pros who cover your area.',
          action: (
            <Link href="/jobs/new" className={buttonClasses({ variant: 'primary', size: 'md' })}>
              Post a job
            </Link>
          ),
        },
        past: {
          title: 'Nothing finished yet',
          body: 'Jobs you complete or cancel move here, with the conversation kept as a record.',
        },
      }}
      action={
        <Link
          href="/jobs/new"
          className={buttonClasses({ variant: 'primary', size: 'md', block: true })}
        >
          Post a job
        </Link>
      }
    />
  );
}

/* ───────────────────────────────── pro ──────────────────────────────── */

function ProJobs({ state, onChange }: { state: JobsState; onChange: (next: JobsState) => void }) {
  const jobs = api.job.mineForPro.useQuery(undefined, { refetchInterval: 30_000 });

  const byId = new Map((jobs.data ?? []).map((j) => [j.id, j]));

  const rows: JobRowData[] = (jobs.data ?? []).map((j) => ({
    id: j.id,
    title: j.title,
    status: j.status,
    // The customer, not the trade — a plumber's list of plumbing jobs does not
    // need to say "Plumber" eleven times.
    subtitle: j.clientName ?? 'Customer',
    createdAt: j.createdAt,
    unreadCount: j.unreadCount,
    lastMessageAt: j.lastMessageAt,
    nextBookingAt: j.nextBookingAt,
  }));
  const active = (jobs.data ?? []).filter((j) => j.isActive).map((j) => j.id);

  return (
    <JobList
      perspective="pro"
      loading={jobs.isLoading}
      rows={rows}
      activeIds={new Set(active)}
      state={state}
      onChange={onChange}
      // A pro's row is one match, so it opens the conversation directly. There
      // is no middle screen listing "the pros on this job" — that is them.
      onOpen={(jobId) => {
        const match = byId.get(jobId);
        if (!match) return;
        onChange({ ...state, view: { kind: 'thread', matchId: match.matchId, jobId: null } });
      }}
      empty={{
        current: {
          title: 'No live jobs',
          body: 'Jobs you accept from your inbox appear here, with the customer chat attached.',
        },
        past: {
          title: 'No finished jobs yet',
          body: 'Work you complete moves here, and the customer can leave you a review.',
        },
      }}
    />
  );
}

/* ─────────────────────────────── shared ─────────────────────────────── */

interface EmptyCopy {
  title: string;
  body: string;
  action?: React.ReactNode;
}

function JobList({
  perspective,
  loading,
  rows,
  activeIds,
  state,
  onChange,
  onOpen,
  empty,
  action,
}: {
  perspective: Perspective;
  loading: boolean;
  rows: JobRowData[];
  activeIds: Set<string>;
  state: JobsState;
  onChange: (next: JobsState) => void;
  onOpen: (jobId: string) => void;
  empty: Record<JobsSegment, EmptyCopy>;
  action?: React.ReactNode;
}) {
  const current = rows.filter((r) => activeIds.has(r.id));
  const past = rows.filter((r) => !activeIds.has(r.id));
  const shown = state.segment === 'current' ? current : past;
  const copy = empty[state.segment];

  return (
    <Shell>
      <h1 className="mb-4 text-h2">Jobs</h1>

      {/* Counts are rendered even at zero — a missing number reads as loading. */}
      <Segmented
        label="Job list view"
        value={state.segment}
        onChange={(segment) => onChange({ ...state, segment })}
        segments={[
          { id: 'current', label: 'Current', count: current.length },
          { id: 'past', label: 'Past', count: past.length },
        ]}
      />

      {/* Past only: a review belongs beside finished work, not beside a job
          somebody is still waiting on. */}
      {state.segment === 'past' && (
        <div className="mt-5">
          <PendingReviews />
        </div>
      )}

      {loading ? (
        <div className="mt-5 flex flex-col gap-3">
          <JobRowSkeleton />
          <JobRowSkeleton />
          <JobRowSkeleton />
        </div>
      ) : shown.length === 0 ? (
        <EmptyState className="mt-5" title={copy.title} body={copy.body} action={copy.action} />
      ) : (
        <>
          {action && <div className="mt-5">{action}</div>}
          <ul className="mt-3 flex flex-col gap-3">
            {shown.map((job) => (
              <li key={job.id}>
                <JobRow job={job} perspective={perspective} onOpen={onOpen} />
              </li>
            ))}
          </ul>
        </>
      )}
    </Shell>
  );
}