import { useState, useEffect } from 'react';
import {
  Title, Text, Card, Stack, Group, SimpleGrid, Badge, ThemeIcon, Divider,
  Tabs, Button, Switch, Loader,
} from '@mantine/core';
import {
  IconBuilding, IconUser, IconSettings, IconShieldLock,
  IconFingerprint, IconLink, IconLogout, IconCreditCard,
} from '@tabler/icons-react';
import { notifications } from '@mantine/notifications';
import { useAuthStore } from '../../stores/authStore';
import { usePreferencesStore } from '../../stores/preferencesStore';
import { MfaSettings } from './MfaSettings';
import { PasskeySettings } from './PasskeySettings';
import { LinkedAccounts } from './LinkedAccounts';
import api from '../../services/api';

interface SubscriptionInfo {
  plan: string;
  planName: string;
  billingInterval: string;
  status: string;
  collectionMethod: string;
  trialEndsAt: string | null;
  currentPeriodEnd: string | null;
  cancelAtPeriodEnd: boolean;
}

const statusColors: Record<string, string> = {
  active: 'green',
  trial: 'blue',
  past_due: 'orange',
  archived: 'red',
  suspended: 'red',
};

export function SettingsPage() {
  const { user, currentOrg } = useAuthStore();
  const { compactView, toggleCompactView } = usePreferencesStore();
  const [loggingOutAll, setLoggingOutAll] = useState(false);
  const [subscription, setSubscription] = useState<SubscriptionInfo | null>(null);
  const [subLoading, setSubLoading] = useState(true);
  const [portalLoading, setPortalLoading] = useState(false);

  useEffect(() => {
    api.get('/billing/subscription')
      .then(({ data }) => setSubscription(data))
      .catch(() => { /* billing not configured or no subscription */ })
      .finally(() => setSubLoading(false));
  }, []);

  const handleLogoutEverywhere = async () => {
    setLoggingOutAll(true);
    try {
      await api.post('/auth/logout-everywhere');
      notifications.show({ message: 'All other sessions have been logged out', color: 'green' });
    } catch {
      notifications.show({ message: 'Failed to log out other sessions', color: 'red' });
    } finally {
      setLoggingOutAll(false);
    }
  };

  const handleManageBilling = async () => {
    setPortalLoading(true);
    try {
      const { data } = await api.post('/billing/portal');
      if (data.url) {
        window.location.href = data.url;
      }
    } catch {
      notifications.show({ message: 'Unable to open billing portal', color: 'red' });
    } finally {
      setPortalLoading(false);
    }
  };

  const formatInterval = (interval: string) => {
    return interval === 'year' ? 'Annual' : 'Monthly';
  };

  const formatDate = (iso: string | null) => {
    if (!iso) return null;
    return new Date(iso).toLocaleDateString('en-US', {
      year: 'numeric', month: 'short', day: 'numeric',
    });
  };

  return (
    <Stack>
      <div>
        <Title order={2}>Settings</Title>
        <Text c="dimmed" size="sm">Organization and account settings</Text>
      </div>

      <SimpleGrid cols={{ base: 1, md: 2 }}>
        {/* Organization Info */}
        <Card withBorder padding="lg">
          <Group mb="md">
            <ThemeIcon color="blue" variant="light" size={40} radius="md">
              <IconBuilding size={24} />
            </ThemeIcon>
            <div>
              <Text fw={600} size="lg">Organization</Text>
              <Text c="dimmed" size="sm">Current organization details</Text>
            </div>
          </Group>
          <Stack gap="xs">
            <Group justify="space-between">
              <Text size="sm" c="dimmed">Name</Text>
              <Text size="sm" fw={500}>{currentOrg?.name || 'N/A'}</Text>
            </Group>
            <Group justify="space-between">
              <Text size="sm" c="dimmed">Your Role</Text>
              <Badge variant="light">{currentOrg?.role || 'N/A'}</Badge>
            </Group>
          </Stack>
        </Card>

        {/* Billing / Subscription */}
        <Card withBorder padding="lg">
          <Group mb="md">
            <ThemeIcon color="teal" variant="light" size={40} radius="md">
              <IconCreditCard size={24} />
            </ThemeIcon>
            <div>
              <Text fw={600} size="lg">Billing</Text>
              <Text c="dimmed" size="sm">Subscription and payment</Text>
            </div>
          </Group>
          {subLoading ? (
            <Group justify="center" py="md"><Loader size="sm" /></Group>
          ) : subscription ? (
            <Stack gap="xs">
              <Group justify="space-between">
                <Text size="sm" c="dimmed">Plan</Text>
                <Group gap={4}>
                  <Badge variant="light">{subscription.planName}</Badge>
                  <Badge variant="light" color="gray" size="sm">{formatInterval(subscription.billingInterval)}</Badge>
                </Group>
              </Group>
              <Group justify="space-between">
                <Text size="sm" c="dimmed">Status</Text>
                <Badge
                  color={statusColors[subscription.status] || 'gray'}
                  variant="light"
                >
                  {subscription.status === 'past_due' ? 'Past Due' : subscription.status}
                  {subscription.cancelAtPeriodEnd ? ' (Canceling)' : ''}
                </Badge>
              </Group>
              {subscription.trialEndsAt && subscription.status === 'trial' && (
                <Group justify="space-between">
                  <Text size="sm" c="dimmed">Trial Ends</Text>
                  <Text size="sm" fw={500}>{formatDate(subscription.trialEndsAt)}</Text>
                </Group>
              )}
              {subscription.currentPeriodEnd && subscription.status !== 'trial' && (
                <Group justify="space-between">
                  <Text size="sm" c="dimmed">Current Period Ends</Text>
                  <Text size="sm" fw={500}>{formatDate(subscription.currentPeriodEnd)}</Text>
                </Group>
              )}
              {subscription.collectionMethod === 'send_invoice' && (
                <Group justify="space-between">
                  <Text size="sm" c="dimmed">Payment</Text>
                  <Badge variant="light" color="cyan" size="sm">Invoice / ACH</Badge>
                </Group>
              )}
              <Button
                variant="light"
                color="teal"
                size="sm"
                leftSection={<IconCreditCard size={16} />}
                onClick={handleManageBilling}
                loading={portalLoading}
                mt="xs"
              >
                Manage Billing
              </Button>
            </Stack>
          ) : (
            <Text size="sm" c="dimmed">No active subscription</Text>
          )}
        </Card>

        {/* User Profile */}
        <Card withBorder padding="lg">
          <Group mb="md">
            <ThemeIcon color="green" variant="light" size={40} radius="md">
              <IconUser size={24} />
            </ThemeIcon>
            <div>
              <Text fw={600} size="lg">Your Profile</Text>
              <Text c="dimmed" size="sm">Account information</Text>
            </div>
          </Group>
          <Stack gap="xs">
            <Group justify="space-between">
              <Text size="sm" c="dimmed">Name</Text>
              <Text size="sm" fw={500}>{user?.firstName} {user?.lastName}</Text>
            </Group>
            <Group justify="space-between">
              <Text size="sm" c="dimmed">Email</Text>
              <Text size="sm" fw={500}>{user?.email}</Text>
            </Group>
            <Group justify="space-between">
              <Text size="sm" c="dimmed">User ID</Text>
              <Text size="sm" ff="monospace" c="dimmed">{user?.id?.slice(0, 8)}...</Text>
            </Group>
          </Stack>
        </Card>

        {/* System Info */}
        <Card withBorder padding="lg">
          <Group mb="md">
            <ThemeIcon color="violet" variant="light" size={40} radius="md">
              <IconSettings size={24} />
            </ThemeIcon>
            <div>
              <Text fw={600} size="lg">System</Text>
              <Text c="dimmed" size="sm">Platform information</Text>
            </div>
          </Group>
          <Stack gap="xs">
            <Group justify="space-between">
              <Text size="sm" c="dimmed">Platform</Text>
              <Text size="sm" fw={500}>HOA LedgerIQ</Text>
            </Group>
            <Group justify="space-between">
              <Text size="sm" c="dimmed">Version</Text>
              <Badge variant="light">2026.03.18</Badge>
            </Group>
            <Group justify="space-between">
              <Text size="sm" c="dimmed">API</Text>
              <Text size="sm" ff="monospace" c="dimmed">/api/docs</Text>
            </Group>
            <Divider />
            <Group justify="space-between">
              <div>
                <Text size="sm">Compact View</Text>
                <Text size="xs" c="dimmed">Reduce spacing in tables and lists</Text>
              </div>
              <Switch checked={compactView} onChange={toggleCompactView} />
            </Group>
          </Stack>
        </Card>

        {/* Sessions */}
        <Card withBorder padding="lg">
          <Group mb="md">
            <ThemeIcon color="orange" variant="light" size={40} radius="md">
              <IconLogout size={24} />
            </ThemeIcon>
            <div>
              <Text fw={600} size="lg">Sessions</Text>
              <Text c="dimmed" size="sm">Manage active sessions</Text>
            </div>
          </Group>
          <Stack gap="xs">
            <Group justify="space-between">
              <Text size="sm" c="dimmed">Current Session</Text>
              <Badge color="green" variant="light">Active</Badge>
            </Group>
            <Button
              variant="light"
              color="orange"
              size="sm"
              leftSection={<IconLogout size={16} />}
              onClick={handleLogoutEverywhere}
              loading={loggingOutAll}
              mt="xs"
            >
              Log Out All Other Sessions
            </Button>
          </Stack>
        </Card>
      </SimpleGrid>

      <Divider my="md" />

      {/* Security Settings */}
      <div>
        <Title order={3} mb="sm">Security</Title>
        <Text c="dimmed" size="sm" mb="md">Manage authentication methods and security settings</Text>
      </div>

      <Tabs defaultValue="mfa">
        <Tabs.List>
          <Tabs.Tab value="mfa" leftSection={<IconShieldLock size={16} />}>
            Two-Factor Auth
          </Tabs.Tab>
          <Tabs.Tab value="passkeys" leftSection={<IconFingerprint size={16} />}>
            Passkeys
          </Tabs.Tab>
          <Tabs.Tab value="linked" leftSection={<IconLink size={16} />}>
            Linked Accounts
          </Tabs.Tab>
        </Tabs.List>

        <Tabs.Panel value="mfa" pt="md">
          <MfaSettings />
        </Tabs.Panel>

        <Tabs.Panel value="passkeys" pt="md">
          <PasskeySettings />
        </Tabs.Panel>

        <Tabs.Panel value="linked" pt="md">
          <LinkedAccounts />
        </Tabs.Panel>
      </Tabs>
    </Stack>
  );
}