import { useMemo, useState } from "react";
import { Check, ShieldCheck } from "lucide-react";
import {
  Stack,
  Group,
  Text,
  Badge,
  Button,
  Box,
  Modal,
} from "@mantine/core";
import type { Freight } from "@edr/types";

import { formatContractApprovalProgress } from "@/features/contracts/contract-approval-progress";
import { SectionCard } from "@/components/bookings/detail/SectionCard";
import type { useContractMutations } from "@/hooks/contracts/useContracts";

type Mutations = ReturnType<typeof useContractMutations>;

interface ContractApprovalStepsCardProps {
  contract: Freight.IContract;
  mutations: Mutations;
}

/** Approval chain with inline approve on the next pending step. */
export function ContractApprovalStepsCard({
  contract,
  mutations,
}: ContractApprovalStepsCardProps) {
  const [confirmOpen, setConfirmOpen] = useState(false);
  const [pendingStep, setPendingStep] =
    useState<Freight.IContractApprovalStep | null>(null);

  const steps = useMemo(
    () =>
      [...(contract.approvalSteps ?? [])].sort(
        (a, b) => a.stepOrder - b.stepOrder,
      ),
    [contract.approvalSteps],
  );

  const nextPending = steps.find((s) => s.status === "PENDING");
  const summary = formatContractApprovalProgress(contract.status, steps);

  const openApprove = (step: Freight.IContractApprovalStep) => {
    setPendingStep(step);
    setConfirmOpen(true);
  };

  const closeApprove = () => {
    setConfirmOpen(false);
    setPendingStep(null);
  };

  const runApprove = () => {
    if (!pendingStep) return;
    mutations.approveStep.mutate(
      { stepId: pendingStep.id, requiredRole: pendingStep.requiredRole },
      { onSuccess: () => closeApprove() },
    );
  };

  const subtitle =
    summary.detail ||
    (nextPending
      ? `Next: ${nextPending.requiredRole} · step ${nextPending.stepOrder}`
      : steps.length
        ? "All steps complete"
        : "Accept submission to begin");

  return (
    <>
      <SectionCard
        icon={ShieldCheck}
        title="Approval chain"
        extra={
          <Badge color="edr-green" variant="light" radius="sm">
            {steps.filter((s) => s.status === "APPROVED").length}/{steps.length}
          </Badge>
        }
      >
        <Text size="xs" c="dimmed" mb="sm">
          {subtitle}
        </Text>

        {steps.length === 0 ? (
          <Text
            size="sm"
            c="dimmed"
            ta="center"
            py="lg"
            px="md"
            style={{
              borderRadius: 8,
              border: "1px dashed var(--mantine-color-gray-3)",
              background: "var(--mantine-color-gray-0)",
            }}
          >
            Use <strong>Accept for approval</strong> in staff actions to
            instantiate steps.
          </Text>
        ) : (
          <Stack gap="xs">
            {steps.map((step) => (
              <StepRow
                key={step.id}
                step={step}
                isNext={nextPending?.id === step.id}
                isPending={mutations.approveStep.isPending}
                onApprove={() => openApprove(step)}
              />
            ))}
          </Stack>
        )}
      </SectionCard>

      <Modal
        opened={confirmOpen}
        onClose={closeApprove}
        title="Approve this step?"
        radius="md"
        centered
      >
        <Stack gap="md">
          <Text size="sm" c="dimmed">
            You are about to approve the{" "}
            <Text span fw={600} c="dark">
              {pendingStep?.requiredRole}
            </Text>{" "}
            step for contract{" "}
            <Text span fw={600} c="dark">
              {contract.reference}
            </Text>
            . This action cannot be undone from this screen.
          </Text>
          <Group justify="flex-end" gap="sm">
            <Button variant="default" radius="md" onClick={closeApprove}>
              Cancel
            </Button>
            <Button
              color="edr-green"
              radius="md"
              leftSection={<Check size={16} />}
              loading={mutations.approveStep.isPending}
              onClick={runApprove}
            >
              Confirm approval
            </Button>
          </Group>
        </Stack>
      </Modal>
    </>
  );
}

function StepRow({
  step,
  isNext,
  isPending,
  onApprove,
}: {
  step: Freight.IContractApprovalStep;
  isNext: boolean;
  isPending: boolean;
  onApprove: () => void;
}) {
  const statusColor =
    step.status === "APPROVED"
      ? "edr-green"
      : step.status === "REJECTED"
        ? "red"
        : isNext
          ? "edr-green"
          : "gray";

  return (
    <Group
      justify="space-between"
      wrap="nowrap"
      gap="sm"
      px="sm"
      py="xs"
      style={{
        borderRadius: 8,
        border: "1px solid var(--mantine-color-gray-2)",
        borderLeft: isNext
          ? "3px solid var(--freight-brand)"
          : "1px solid var(--mantine-color-gray-2)",
        background: isNext ? "var(--mantine-color-gray-0)" : "white",
      }}
    >
      <Group gap="sm" wrap="nowrap" style={{ minWidth: 0 }}>
        <Box
          style={{
            display: "flex",
            alignItems: "center",
            justifyContent: "center",
            width: 28,
            height: 28,
            borderRadius: 8,
            flexShrink: 0,
            fontSize: 12,
            fontWeight: 700,
            background: "var(--mantine-color-gray-1)",
            color: isNext
              ? "var(--mantine-color-gray-7)"
              : "var(--mantine-color-gray-6)",
          }}
        >
          {step.stepOrder}
        </Box>
        <Box style={{ minWidth: 0 }}>
          <Text size="sm" fw={600}>
            {step.requiredRole}
          </Text>
          {step.note && (
            <Text size="xs" c="dimmed" truncate>
              {step.note}
            </Text>
          )}
        </Box>
      </Group>
      <Group gap="xs" wrap="nowrap" style={{ flexShrink: 0 }}>
        {isNext && step.status === "PENDING" && (
          <Button
            size="compact-sm"
            color="edr-green"
            leftSection={<Check size={14} />}
            disabled={isPending}
            onClick={onApprove}
          >
            Approve
          </Button>
        )}
        <Badge
          variant="light"
          color={statusColor}
          size="sm"
          radius="sm"
          tt="uppercase"
        >
          {step.status}
        </Badge>
      </Group>
    </Group>
  );
}