"use client";

import { useState } from "react";
import { useRouter } from "next/navigation";
import { approvePo, rejectPo, requestEdits, requestVendorId } from "./actions";
import { formatCurrency } from "@/lib/utils";
import type { POStatus } from "@prisma/client";

// Resolve the slider percent (whole number) into an absolute advance amount.
// 100% is the exact total (no rounding loss on paise); partial advances are
// rounded to whole rupees — the slider is convenience, the amount is the record.
function advanceAmount(total: number, percent: number): number {
  if (percent >= 100) return total;
  if (percent <= 0) return 0;
  return Math.round((total * percent) / 100);
}

export function ApprovalActions({
  poId,
  poStatus,
  totalAmount = 0,
  currency = "INR",
}: {
  poId: string;
  poStatus: POStatus;
  totalAmount?: number;
  currency?: string;
}) {
  const router = useRouter();
  const [note, setNote] = useState("");
  const [advancePercent, setAdvancePercent] = useState(100);
  const [activeAction, setActiveAction] = useState<string | null>(null);
  const [pending, setPending] = useState<string | null>(null);
  const [error, setError] = useState("");

  const advance = advanceAmount(totalAmount, advancePercent);

  async function dispatch(action: string, requireNote = false) {
    if (requireNote && !note.trim()) {
      setError("A note is required for this action.");
      return;
    }
    setPending(action);
    setError("");
    let result: { ok: true } | { error: string } | undefined;
    // Approvals carry the Manager's advance decision (resolved amount, not %).
    if (action === "approve") result = await approvePo({ poId, note, suggestedAdvancePayment: advance });
    else if (action === "approve_note")
      result = await approvePo({ poId, note, withNote: true, suggestedAdvancePayment: advance });
    else if (action === "reject") result = await rejectPo({ poId, note });
    else if (action === "request_edits") result = await requestEdits({ poId, note });
    else if (action === "request_vendor_id") result = await requestVendorId({ poId });

    if (result && "error" in result) {
      setError(result.error);
      setPending(null);
    } else {
      router.push("/approvals");
      router.refresh();
    }
  }

  return (
    <div className="rounded-lg border border-neutral-200 bg-white p-4 md:p-6">
      <h3 className="text-base font-semibold text-neutral-900 mb-4">Decision</h3>

      {/* Advance payment (issue #92) — Manager decides how much Accounts pays
          first. 100% = full payment; lower values seed the first part-payment. */}
      <div className="mb-5 rounded-lg border border-neutral-200 bg-neutral-50 p-3.5">
        <div className="flex items-center justify-between mb-2">
          <label htmlFor="advance-slider" className="text-sm font-medium text-neutral-700">
            Advance payment
          </label>
          <span className="text-sm font-semibold text-neutral-900 tabular-nums">
            {advancePercent}% · {formatCurrency(advance, currency)}
          </span>
        </div>
        <input
          id="advance-slider"
          type="range"
          min={0}
          max={100}
          step={1}
          value={advancePercent}
          onChange={(e) => setAdvancePercent(Number(e.target.value))}
          className="w-full accent-primary-600"
        />
        <p className="mt-1.5 text-xs text-neutral-500">
          {advancePercent >= 100
            ? "Full payment — Accounts will be prompted to pay the whole PO value."
            : `Accounts will be prompted to pay ${formatCurrency(advance, currency)} first; the balance of ${formatCurrency(
                Math.max(totalAmount - advance, 0),
                currency
              )} follows the usual part-payment flow.`}
        </p>
      </div>

      {(activeAction === "reject" || activeAction === "request_edits" || activeAction === "approve_note") && (
        <div className="mb-4">
          <label className="block text-sm font-medium text-neutral-700 mb-1.5">
            Note {activeAction !== "approve_note" ? "(required)" : "(optional)"}
          </label>
          <textarea
            rows={3}
            value={note}
            onChange={(e) => setNote(e.target.value)}
            className="w-full rounded-lg border border-neutral-300 px-3 py-2.5 text-sm focus:border-primary-500 focus:outline-none focus:ring-2 focus:ring-primary-500/20 resize-none"
            placeholder={
              activeAction === "reject"
                ? "Reason for rejection…"
                : activeAction === "request_edits"
                ? "What needs to be changed…"
                : "Optional note for the submitter…"
            }
          />
        </div>
      )}

      {error && (
        <p className="mb-4 text-sm text-danger-700 bg-danger-50 rounded-lg px-3 py-2">{error}</p>
      )}

      <div className="flex flex-col sm:flex-row flex-wrap items-stretch sm:items-center gap-2 sm:gap-3">
        <button
          onClick={() => {
            setActiveAction("reject");
            if (activeAction === "reject") dispatch("reject", true);
          }}
          disabled={!!pending}
          className="w-full sm:w-auto rounded-lg border border-danger bg-danger-50 px-4 py-2.5 text-sm font-medium text-danger-700 hover:bg-danger-100 disabled:opacity-60 transition-colors"
        >
          {pending === "reject" ? "Rejecting…" : activeAction === "reject" ? "Confirm Reject" : "Reject"}
        </button>
        <button
          onClick={() => {
            setActiveAction("request_edits");
            if (activeAction === "request_edits") dispatch("request_edits", true);
          }}
          disabled={!!pending}
          className="w-full sm:w-auto rounded-lg border border-warning bg-warning-50 px-4 py-2.5 text-sm font-medium text-warning-700 hover:bg-warning-100 disabled:opacity-60 transition-colors"
        >
          {pending === "request_edits" ? "Sending…" : activeAction === "request_edits" ? "Send Edit Request" : "Request Edits"}
        </button>
        <button
          onClick={() => dispatch("request_vendor_id")}
          disabled={!!pending}
          className="w-full sm:w-auto rounded-lg border border-neutral-300 bg-white px-4 py-2.5 text-sm font-medium text-neutral-700 hover:bg-neutral-50 disabled:opacity-60 transition-colors"
        >
          {pending === "request_vendor_id" ? "Sending…" : "Request Vendor ID"}
        </button>
        <button
          onClick={() => {
            setActiveAction("approve_note");
            if (activeAction === "approve_note") dispatch("approve_note");
          }}
          disabled={!!pending}
          className="w-full sm:w-auto rounded-lg border border-neutral-300 bg-white px-4 py-2.5 text-sm font-medium text-neutral-700 hover:bg-neutral-50 disabled:opacity-60 transition-colors"
        >
          {pending === "approve_note" ? "Approving…" : activeAction === "approve_note" ? "Confirm Approve with Remarks" : "Approve with Remarks"}
        </button>
        <button
          onClick={() => dispatch("approve")}
          disabled={!!pending}
          className="w-full sm:w-auto rounded-lg bg-success px-4 py-2.5 text-sm font-semibold text-white hover:opacity-90 disabled:opacity-60 transition-opacity"
        >
          {pending === "approve" ? "Approving…" : "Approve"}
        </button>
      </div>
    </div>
  );
}