import { Suspense } from "react";
import { ReportsPageClient } from "@/components/reports/ReportsPageClient";
import {
  aggregateReport,
  DATE_SCOPED_MEASURES,
  type GroupDimension,
  type Measure,
  type OrgLookups,
  type ReportEmployee,
} from "@/lib/reports";
import { createClient } from "@/lib/supabase/server";
import type { EmploymentStatus, EmploymentType } from "@/lib/supabase/types";

type SearchParams = {
  measure?: string;
  group?: string;
  split?: string;
  division?: string;
  location?: string;
  status?: string;
  employment?: string;
  from?: string;
  to?: string;
};

export default async function ReportsPage({ searchParams }: { searchParams: Promise<SearchParams> }) {
  const params = await searchParams;
  const supabase = await createClient();

  const measure = (params.measure as Measure) || "headcount";
  const group = (params.group as GroupDimension) || "division";
  const split = (params.split as GroupDimension) || undefined;

  const [{ data: divisions }, { data: departments }, { data: teams }, { data: locations }] = await Promise.all([
    supabase.from("divisions").select("id, name").order("name"),
    supabase.from("departments").select("id, name"),
    supabase.from("teams").select("id, name, department_id"),
    supabase.from("locations").select("id, name").order("name"),
  ]);

  const departmentNameById = new Map((departments ?? []).map((d) => [d.id, d.name]));
  const lookups: OrgLookups = {
    divisionName: new Map((divisions ?? []).map((d) => [d.id, d.name])),
    departmentNameByTeam: new Map((teams ?? []).map((t) => [t.id, departmentNameById.get(t.department_id) ?? "Unbekannt"])),
    teamName: new Map((teams ?? []).map((t) => [t.id, t.name])),
    locationName: new Map((locations ?? []).map((l) => [l.id, l.name])),
  };

  let query = supabase
    .from("employees")
    .select(
      "id, first_name, last_name, job_title, division_id, team_id, location_id, status, employment_type, contract_type, entry_date, exit_date, weekly_hours, source, paygrade, birth_date, gender"
    );

  if (params.division) query = query.eq("division_id", params.division);
  if (params.location) query = query.eq("location_id", params.location);
  if (params.status) query = query.eq("status", params.status as EmploymentStatus);
  if (params.employment) query = query.eq("employment_type", params.employment as EmploymentType);

  const isDateScoped = DATE_SCOPED_MEASURES.includes(measure);
  const currentYear = new Date().getFullYear();
  const from = params.from || `${currentYear}-01-01`;
  const to = params.to || `${currentYear}-12-31`;
  if (isDateScoped) {
    if (measure === "hires") query = query.gte("entry_date", from).lte("entry_date", to);
    else query = query.gte("exit_date", from).lte("exit_date", to).not("exit_date", "is", null);
  } else if (!params.status) {
    query = query.in("status", ["Aktiv", "Karenz"]);
  }

  const { data: employeesData } = await query;
  const employees = (employeesData ?? []) as ReportEmployee[];

  const rows = aggregateReport(employees, measure, group, split ?? null, lookups);
  const total = measureValueForTotal(rows, measure);

  const {
    data: { user },
  } = await supabase.auth.getUser();
  const { data: savedReports } = user
    ? await supabase.from("saved_reports").select("id, name, config").eq("created_by", user.id).order("created_at", { ascending: false })
    : { data: [] };

  return (
    <Suspense>
      <ReportsPageClient
        measure={measure}
        group={group}
        split={split ?? ""}
        filters={{
          division: params.division ?? "",
          location: params.location ?? "",
          status: params.status ?? "",
          employment: params.employment ?? "",
          from: params.from ?? "",
          to: params.to ?? "",
        }}
        rows={rows}
        total={total}
        recordCount={employees.length}
        divisions={divisions ?? []}
        locations={locations ?? []}
        savedReports={savedReports ?? []}
      />
    </Suspense>
  );
}

function measureValueForTotal(rows: { value: number; count: number }[], measure: Measure): number {
  if (["headcount", "fte", "hires", "exits"].includes(measure)) {
    return rows.reduce((s, r) => s + r.value, 0);
  }
  // averages/ratios: weight by underlying count for a sensible overall figure
  const totalCount = rows.reduce((s, r) => s + r.count, 0);
  if (totalCount === 0) return 0;
  return rows.reduce((s, r) => s + r.value * r.count, 0) / totalCount;
}
