import { auth } from "@/auth";
import { db } from "@/lib/db";
import { hasPermission } from "@/lib/permissions";
import { redirect } from "next/navigation";
import Link from "next/link";
import { formatCurrency, formatDate } from "@/lib/utils";
import { ApprovalsSearch } from "./approvals-search";
import { CREWING_ENABLED } from "@/lib/feature-flags";
import { CrewingApprovals, type CrewApprovalItem, type CrewApprovalKind } from "./crewing-approvals";
import { Suspense } from "react";
import type { Metadata } from "next";

export const metadata: Metadata = { title: "Approvals" };

interface Props {
  searchParams: Promise<{
    q?: string;
    vesselId?: string;
    dateFrom?: string;
  }>;
}

export default async function ApprovalsPage({ searchParams }: Props) {
  const session = await auth();
  if (!session?.user) redirect("/login");

  if (!hasPermission(session.user.role, "approve_po")) redirect("/dashboard");

  const { q, vesselId, dateFrom } = await searchParams;

  const where: NonNullable<Parameters<typeof db.purchaseOrder.findMany>[0]>["where"] = {
    status: "MGR_REVIEW",
  };

  if (q?.trim()) {
    where.OR = [
      { poNumber: { contains: q.trim(), mode: "insensitive" } },
      { submitter: { name: { contains: q.trim(), mode: "insensitive" } } },
      { title: { contains: q.trim(), mode: "insensitive" } },
    ];
  }
  if (vesselId) where.vesselId = vesselId;
  if (dateFrom) where.submittedAt = { gte: new Date(dateFrom) };

  const [pending, vessels] = await Promise.all([
    db.purchaseOrder.findMany({
      where,
      include: { submitter: true, vessel: true, account: true },
      orderBy: { submittedAt: "asc" },
    }),
    db.vessel.findMany({ orderBy: { name: "asc" }, select: { id: true, name: true } }),
  ]);

  // Crewing approvals (spec §8.13 R8) — the same unified Manager queue. Pending
  // SALARY / SELECTION / WAIVER gates surface here alongside POs.
  const role = session.user.role;
  const showCrewing =
    CREWING_ENABLED &&
    (hasPermission(role, "approve_salary_structure") ||
      hasPermission(role, "select_candidate") ||
      hasPermission(role, "approve_interview_waiver") ||
      hasPermission(role, "decide_leave") ||
      hasPermission(role, "approve_appraisal"));

  const crewGates = showCrewing
    ? await db.applicationGate.findMany({
        where: { result: "PENDING", gate: { in: ["SALARY", "SELECTION", "WAIVER"] } },
        orderBy: { createdAt: "asc" },
        include: {
          application: {
            include: {
              crewMember: { select: { name: true } },
              requisition: { select: { code: true, rank: { select: { name: true } } } },
              salaryStructures: { where: { approvedById: null }, orderBy: { createdAt: "desc" }, take: 1 },
            },
          },
        },
      })
    : [];

  const crewItems: CrewApprovalItem[] = crewGates.map((g) => {
    const sal = g.application.salaryStructures[0];
    const detail =
      g.gate === "SALARY" && sal
        ? `${sal.currency} ${Number(sal.basic).toLocaleString("en-IN")} / ${sal.rateBasis.toLowerCase()}`
        : g.gate === "WAIVER"
          ? "Returning crew — interview waiver"
          : "Interview cleared";
    return {
      id: g.applicationId,
      kind: g.gate as CrewApprovalKind,
      candidateName: g.application.crewMember.name,
      rank: g.application.requisition.rank.name,
      requisitionCode: g.application.requisition.code,
      detail,
      link: `/crewing/applications/${g.applicationId}`,
    };
  });

  // Pending leave requests (Manager decides) — the §8.13 "Leave" queue kind.
  const leaveItems: CrewApprovalItem[] = (showCrewing && hasPermission(role, "decide_leave"))
    ? (await db.leaveRequest.findMany({
        where: { status: "APPLIED" },
        orderBy: { createdAt: "asc" },
        include: { assignment: { include: { crewMember: { select: { name: true } }, rank: { select: { name: true } } } } },
      })).map((l) => ({
        id: l.id,
        kind: "LEAVE" as CrewApprovalKind,
        candidateName: l.assignment.crewMember.name,
        rank: l.assignment.rank.name,
        requisitionCode: `${l.fromDate.toLocaleDateString()}–${l.toDate.toLocaleDateString()}`,
        detail: l.type.toLowerCase(),
        link: "/crewing/leave",
      }))
    : [];

  // MPO-verified appraisals awaiting Manager approval (§8.13/§8.14).
  const appraisalItems: CrewApprovalItem[] = (showCrewing && hasPermission(role, "approve_appraisal"))
    ? (await db.appraisal.findMany({
        where: { status: "MPO_VERIFIED" },
        orderBy: { createdAt: "asc" },
        include: { assignment: { include: { crewMember: { select: { name: true } }, rank: { select: { name: true } } } } },
      })).map((a) => ({
        id: a.id,
        kind: "APPRAISAL" as CrewApprovalKind,
        candidateName: a.assignment.crewMember.name,
        rank: a.assignment.rank.name,
        requisitionCode: a.period,
        detail: "MPO-verified appraisal",
        link: "/approvals",
      }))
    : [];

  const allCrewItems = [...crewItems, ...leaveItems, ...appraisalItems];

  return (
    <div>
      <div className="mb-4">
        <h1 className="text-2xl font-semibold text-neutral-900">Approval Queue</h1>
        <p className="mt-1 text-sm text-neutral-500">
          {pending.length} order{pending.length !== 1 ? "s" : ""} awaiting your decision
        </p>
      </div>

      <Suspense>
        <ApprovalsSearch vessels={vessels} />
      </Suspense>

      {pending.length === 0 ? (
        <div className="rounded-lg border border-neutral-200 bg-white p-12 text-center">
          <p className="text-neutral-500">No purchase orders awaiting approval.</p>
        </div>
      ) : (
        <>
          {/* ── Desktop table ─────────────────────────────────────────── */}
          <div className="hidden md:block rounded-lg border border-neutral-200 bg-white overflow-hidden">
            <table className="w-full text-sm">
              <thead className="bg-neutral-50 border-b border-neutral-200">
                <tr>
                  <th className="px-4 py-3 text-left font-medium text-neutral-600">PO Number</th>
                  <th className="px-4 py-3 text-left font-medium text-neutral-600">Title</th>
                  <th className="px-4 py-3 text-left font-medium text-neutral-600">Submitter</th>
                  <th className="px-4 py-3 text-left font-medium text-neutral-600">Cost Centre</th>
                  <th className="px-4 py-3 text-right font-medium text-neutral-600">Amount</th>
                  <th className="px-4 py-3 text-left font-medium text-neutral-600">Submitted</th>
                  <th className="px-4 py-3"></th>
                </tr>
              </thead>
              <tbody className="divide-y divide-neutral-100">
                {pending.map((po) => (
                  <tr key={po.id} className="hover:bg-neutral-50">
                    <td className="px-4 py-3 font-mono text-xs text-neutral-600">{po.poNumber}</td>
                    <td className="px-4 py-3 font-medium text-neutral-900 max-w-xs truncate">{po.title}</td>
                    <td className="px-4 py-3 text-neutral-600">{po.submitter.name}</td>
                    <td className="px-4 py-3 text-neutral-600">{po.vessel.name}</td>
                    <td className="px-4 py-3 text-right font-mono text-sm">
                      {formatCurrency(Number(po.totalAmount), po.currency)}
                    </td>
                    <td className="px-4 py-3 text-neutral-500">
                      {po.submittedAt ? formatDate(po.submittedAt) : "—"}
                    </td>
                    <td className="px-4 py-3">
                      <Link href={`/approvals/${po.id}`} className="text-primary-600 hover:text-primary-700 font-medium">
                        Review →
                      </Link>
                    </td>
                  </tr>
                ))}
              </tbody>
            </table>
          </div>

          {/* ── Mobile cards ──────────────────────────────────────────── */}
          <div className="md:hidden space-y-3">
            {pending.map((po) => (
              <Link key={po.id} href={`/approvals/${po.id}`} className="block">
                <div className="rounded-xl border border-neutral-200 bg-white p-4 shadow-sm active:bg-neutral-50 transition-colors">
                  <div className="flex items-start justify-between gap-2 mb-1">
                    <span className="font-mono text-xs text-neutral-500">{po.poNumber}</span>
                    <span className="text-xs text-neutral-400 shrink-0">
                      {po.submittedAt ? formatDate(po.submittedAt) : "—"}
                    </span>
                  </div>
                  <p className="font-semibold text-neutral-900 leading-snug mb-2">{po.title}</p>
                  <div className="flex items-center justify-between text-sm">
                    <span className="text-neutral-500 truncate max-w-[55%]">
                      {po.submitter.name} · {po.vessel.name}
                    </span>
                    <span className="font-mono font-semibold text-neutral-900 shrink-0">
                      {formatCurrency(Number(po.totalAmount), po.currency)}
                    </span>
                  </div>
                  <div className="mt-3">
                    <span className="block w-full rounded-lg bg-primary-600 py-2 text-center text-sm font-semibold text-white">
                      Review →
                    </span>
                  </div>
                </div>
              </Link>
            ))}
          </div>
        </>
      )}

      {showCrewing && allCrewItems.length > 0 && <CrewingApprovals items={allCrewItems} />}
    </div>
  );
}