// Small helpers the shop tabs share: the drawing page list, the user's level, the department people.
import { useEffect, useState } from "react";
import { packetsApi, peopleApi } from "../api/packets";
import type { BomLine, DeptPerson, Guarded, PacketPage, PacketRead, PacketStatus, ShortReceipt, TransitionBody } from "../api/types";
import type { Mutate } from "./tabs";
import { parseRole } from "../auth/roles";

/** Live drawing pages first, then the VOID copies (the old viewPages). */
export function viewPages(pages: readonly PacketPage[]): PacketPage[] {
  const dwg = pages.filter((x) => x.type === "drawing");
  return [...dwg.filter((x) => !x.void), ...dwg.filter((x) => !!x.void)];
}

/**
 * The page to show: the one picked when it exists, else the first live page. A VOID page that was not picked on
 * purpose lands on the sheet that replaced it.
 */
export function landingPage(pages: readonly PacketPage[], picked: number | null, onPurpose: boolean): PacketPage | undefined {
  let pg = pages.find((x) => x.n === picked) ?? pages[0];
  for (let i = 0; i < 10 && pg?.void && !onPurpose; i++) {
    const next = pages.find((x) => x.n === pg?.void?.new_n);
    if (!next) break;
    pg = next;
  }
  return pg;
}

/** "M00543 R2 · VOID" for the page buttons. */
export function pageLabel(pg: PacketPage): string {
  return `${pg.dwg || `Page ${pg.n}`}${pg.rev ? ` R${pg.rev}` : ""}${pg.void ? " · VOID" : ""}`;
}

export type Level = "worker" | "lead" | "supervisor";

/** The highest shop level in a department; admin counts as supervisor. */
export function shopLevel(roles: readonly string[], dept: string): Level | null {
  if (roles.includes("admin")) return "supervisor";
  const order: Level[] = ["worker", "lead", "supervisor"];
  let best = -1;
  for (const r of roles) {
    const p = parseRole(r);
    if (p.shop && p.dept === dept) best = Math.max(best, order.indexOf(p.level));
  }
  return best < 0 ? null : (order[best] ?? null);
}

/** May this user verify a change order for the department? Mirrors the server's can_verify. */
export function canVerifyDept(roles: readonly string[], dept: string): boolean {
  if (roles.includes("admin")) return true;
  if (dept === "WH") return roles.includes("warehouse_supervisor");
  if (dept === "QC") return roles.includes("qc_supervisor");
  if (dept === "CL" || dept === "PM") return false;
  return shopLevel(roles, dept) === "supervisor";
}

/** The active people of a shop department, for the welder picker and the weld sheet's stamp. */
export function usePeople(dept: string | null): { people: DeptPerson[]; loaded: boolean; error: string | null } {
  const [state, setState] = useState<{ dept: string | null; people: DeptPerson[]; error: string | null } | null>(null);
  useEffect(() => {
    if (!dept) return;
    const ctl = new AbortController();
    peopleApi
      .list(dept, ctl.signal)
      .then((people) => {
        if (!ctl.signal.aborted) setState({ dept, people, error: null });
      })
      .catch((err: unknown) => {
        if (ctl.signal.aborted) return;
        setState({ dept, people: [], error: err instanceof Error ? err.message : "The people list could not be read." });
      });
    return () => ctl.abort();
  }, [dept]);
  const mine = state && state.dept === dept ? state : null;
  return { people: mine?.people ?? [], loaded: !!mine, error: mine?.error ?? null };
}

export type ShopTab = "checklist" | "welds";

/** The old missing(): what the stall still has to do before Submit, each with the tab that fixes it. */
export function stallMissing(p: PacketRead): Array<{ t: string; tab: ShopTab }> {
  const out: Array<{ t: string; tab: ShopTab }> = [];
  const done = p.stage?.checklist ?? {};
  const open = p.checklist_items.filter((i) => !done[i.key]?.done).length;
  if (open) out.push({ t: `${open} checklist item${open > 1 ? "s" : ""}`, tab: "checklist" });
  if (p.dept.weld !== false) {
    const here = p.welds.some((w) => !w.carried && (w.dept_code === undefined || w.dept_code === null || w.dept_code === p.dept.code));
    if (!here) out.push({ t: "no welds marked on the drawing", tab: "welds" });
    if (!p.stage?.filler) out.push({ t: "filler metal", tab: "checklist" });
  }
  return out;
}

export type StepFn = (
  action: string,
  extra?: Omit<TransitionBody, "action" | "expect">,
  opts?: { sign?: string; ok?: string },
) => Promise<boolean>;

/** A transition with the expect guard, through the page's mutate. */
export function makeStep(p: PacketRead, mutate: Mutate): StepFn {
  const expect: { status: PacketStatus; dept: string } = { status: p.status, dept: p.dept.code };
  return (action, extra = {}, opts = {}) =>
    mutate((g: Guarded) => packetsApi.transition(p.id, { action, expect, ...extra, ...g }), { sign: opts.sign, ok: opts.ok });
}

/**
 * The receipts of a BOM line's shorts, open or closed: `shorts` on the read when the server sends it, else the
 * open short on the line.
 */
export function lineReceipts(p: PacketRead, b: BomLine): ShortReceipt[] {
  if (p.shorts) return p.shorts.filter((s) => s.item === b.item).flatMap((s) => s.receipts ?? []);
  return b.short?.receipts ?? [];
}