import React, { useEffect, useState, useCallback } from 'react';
import { Box, Text, useInput } from 'ink';
import TextInput from 'ink-text-input';
import { useNavigation } from '../../state/navigation-context.js';
import { useProductionOrders } from '../../hooks/useProductionOrders.js';
import { useRecipeNameLookup } from '../../hooks/useRecipeNameLookup.js';
import { client } from '../../utils/api-client.js';
import type { BatchDTO } from '@effigenix/api-client';
import { LoadingSpinner } from '../shared/LoadingSpinner.js';
import { ErrorDisplay } from '../shared/ErrorDisplay.js';
import { SuccessDisplay } from '../shared/SuccessDisplay.js';
import { PRODUCTION_ORDER_STATUS_LABELS, PRIORITY_LABELS } from '@effigenix/api-client';
import type { ProductionOrderStatus, Priority } from '@effigenix/api-client';

const STATUS_COLORS: Record<string, string> = {
  PLANNED: 'gray',
  RELEASED: 'yellow',
  IN_PROGRESS: 'blue',
  COMPLETED: 'green',
  CANCELLED: 'red',
};

type Mode = 'view' | 'menu' | 'start-batch-input' | 'reschedule-input';

export function ProductionOrderDetailScreen() {
  const { params, back } = useNavigation();
  const {
    productionOrder, loading, error,
    fetchProductionOrder, releaseProductionOrder, rescheduleProductionOrder, startProductionOrder, clearError,
  } = useProductionOrders();
  const { recipeName } = useRecipeNameLookup();
  const [mode, setMode] = useState<Mode>('view');
  const [menuIndex, setMenuIndex] = useState(0);
  const [batchId, setBatchId] = useState('');
  const [newDate, setNewDate] = useState('');
  const [success, setSuccess] = useState<string | null>(null);
  const [batch, setBatch] = useState<BatchDTO | null>(null);

  const orderId = params.orderId ?? '';

  useEffect(() => {
    if (orderId) void fetchProductionOrder(orderId);
  }, [fetchProductionOrder, orderId]);

  const loadBatch = useCallback(async (id: string) => {
    try {
      const b = await client.batches.getById(id);
      setBatch(b);
    } catch (err) {
      setBatch(null);
    }
  }, []);

  useEffect(() => {
    if (productionOrder?.batchId) void loadBatch(productionOrder.batchId);
  }, [loadBatch, productionOrder?.batchId]);

  const getMenuItems = () => {
    const items: { label: string; action: string }[] = [];
    const status = productionOrder?.status;
    if (status === 'PLANNED') {
      items.push({ label: 'Freigeben', action: 'release' });
      items.push({ label: 'Umterminieren', action: 'reschedule' });
    }
    if (status === 'RELEASED') {
      items.push({ label: 'Produktion starten', action: 'start' });
      items.push({ label: 'Umterminieren', action: 'reschedule' });
    }
    return items;
  };

  const menuItems = getMenuItems();

  const handleRelease = async () => {
    const result = await releaseProductionOrder(orderId);
    if (result) {
      setSuccess('Produktionsauftrag freigegeben.');
      setMode('view');
    }
  };

  const handleStart = async () => {
    if (!batchId.trim()) return;
    const result = await startProductionOrder(orderId, { batchId: batchId.trim() });
    if (result) {
      setSuccess('Produktion gestartet.');
      setMode('view');
      setBatchId('');
    }
  };

  const handleReschedule = async () => {
    if (!newDate.trim()) return;
    const result = await rescheduleProductionOrder(orderId, newDate.trim());
    if (result) {
      setSuccess(`Umterminiert auf ${newDate.trim()}.`);
      setMode('view');
      setNewDate('');
    }
  };

  useInput((_input, key) => {
    if (loading) return;

    if (mode === 'reschedule-input') {
      if (key.escape) setMode('menu');
      return;
    }

    if (mode === 'start-batch-input') {
      if (key.escape) setMode('menu');
      return;
    }

    if (mode === 'menu') {
      if (key.upArrow) setMenuIndex((i) => Math.max(0, i - 1));
      if (key.downArrow) setMenuIndex((i) => Math.min(menuItems.length - 1, i + 1));
      if (key.return && menuItems[menuIndex]) {
        const action = menuItems[menuIndex].action;
        if (action === 'release') void handleRelease();
        if (action === 'reschedule') {
          setMode('reschedule-input');
          setNewDate('');
        }
        if (action === 'start') {
          setMode('start-batch-input');
          setBatchId('');
        }
      }
      if (key.escape) setMode('view');
      return;
    }

    // view mode
    if (_input === 'm' && menuItems.length > 0) {
      setMode('menu');
      setMenuIndex(0);
    }
    if (key.backspace || key.escape) back();
  });

  if (loading && !productionOrder) return <LoadingSpinner label="Lade Auftrag..." />;

  if (!productionOrder) {
    return (
      <Box flexDirection="column">
        {error && <ErrorDisplay message={error} onDismiss={clearError} />}
        <Text color="red">Produktionsauftrag nicht gefunden.</Text>
      </Box>
    );
  }

  const statusLabel = PRODUCTION_ORDER_STATUS_LABELS[(productionOrder.status ?? '') as ProductionOrderStatus] ?? productionOrder.status;
  const statusColor = STATUS_COLORS[productionOrder.status ?? ''] ?? 'white';
  const prioLabel = PRIORITY_LABELS[(productionOrder.priority ?? '') as Priority] ?? productionOrder.priority;
  const createdAt = productionOrder.createdAt
    ? new Date(productionOrder.createdAt).toLocaleString('de-DE', { dateStyle: 'medium', timeStyle: 'short' })
    : '';
  const updatedAt = productionOrder.updatedAt
    ? new Date(productionOrder.updatedAt).toLocaleString('de-DE', { dateStyle: 'medium', timeStyle: 'short' })
    : '';

  return (
    <Box flexDirection="column" gap={1}>
      <Box gap={2}>
        <Text color="cyan" bold>Produktionsauftrag</Text>
        {loading && <Text color="gray"> (aktualisiere...)</Text>}
      </Box>

      {error && <ErrorDisplay message={error} onDismiss={clearError} />}
      {success && <SuccessDisplay message={success} onDismiss={() => setSuccess(null)} />}

      <Box flexDirection="column" borderStyle="round" borderColor="gray" paddingX={1}>
        <Box><Text color="gray">ID:          </Text><Text>{productionOrder.id}</Text></Box>
        <Box><Text color="gray">Rezept:      </Text><Text>{recipeName(productionOrder.recipeId ?? '') ?? productionOrder.recipeId}</Text><Text color="gray" dimColor> ({productionOrder.recipeId})</Text></Box>
        <Box><Text color="gray">Status:      </Text><Text color={statusColor}>{statusLabel}</Text></Box>
        <Box><Text color="gray">Menge:       </Text><Text>{productionOrder.plannedQuantity} {productionOrder.plannedQuantityUnit}</Text></Box>
        <Box><Text color="gray">Geplant am:  </Text><Text>{productionOrder.plannedDate}</Text></Box>
        <Box><Text color="gray">Priorität:   </Text><Text>{prioLabel}</Text></Box>
        {productionOrder.batchId && (
          <Box><Text color="gray">Chargen-Nr:  </Text><Text>{batch?.batchNumber ?? productionOrder.batchId}</Text></Box>
        )}
        {productionOrder.notes && (
          <Box><Text color="gray">Notizen:     </Text><Text>{productionOrder.notes}</Text></Box>
        )}
        <Box><Text color="gray">Erstellt:    </Text><Text>{createdAt}</Text></Box>
        <Box><Text color="gray">Aktualisiert:</Text><Text> {updatedAt}</Text></Box>
      </Box>

      {batch && productionOrder.batchId && (
        <Box flexDirection="column" borderStyle="round" borderColor="gray" paddingX={1}>
          <Text color="cyan" bold>Produktionsergebnis</Text>
          <Box><Text color="gray">Soll-Menge:  </Text><Text>{batch.plannedQuantity} {batch.plannedQuantityUnit}</Text></Box>
          {batch.actualQuantity && (
            <Box><Text color="gray">Ist-Menge:   </Text><Text color="green">{batch.actualQuantity} {batch.actualQuantityUnit}</Text></Box>
          )}
          {batch.waste && (
            <Box><Text color="gray">Ausschuss:   </Text><Text color="red">{batch.waste} {batch.wasteUnit}</Text></Box>
          )}
          {batch.remarks && (
            <Box><Text color="gray">Bemerkungen: </Text><Text>{batch.remarks}</Text></Box>
          )}
          {batch.completedAt && (
            <Box><Text color="gray">Abgeschl. am:</Text><Text> {new Date(batch.completedAt).toLocaleString('de-DE', { dateStyle: 'medium', timeStyle: 'short' })}</Text></Box>
          )}
        </Box>
      )}

      {mode === 'menu' && (
        <Box flexDirection="column" borderStyle="round" borderColor="cyan" paddingX={1}>
          <Text color="cyan" bold>Aktionen</Text>
          {menuItems.map((item, i) => (
            <Text key={item.action} color={i === menuIndex ? 'cyan' : 'white'}>
              {i === menuIndex ? '▶ ' : '  '}{item.label}
            </Text>
          ))}
          <Text color="gray" dimColor>↑↓ nav · Enter ausführen · Escape zurück</Text>
        </Box>
      )}

      {mode === 'start-batch-input' && (
        <Box flexDirection="column" borderStyle="round" borderColor="yellow" paddingX={1}>
          <Text color="yellow" bold>Chargen-ID eingeben:</Text>
          <Box>
            <Text color="gray"> › </Text>
            <TextInput
              value={batchId}
              onChange={setBatchId}
              onSubmit={() => void handleStart()}
              focus={true}
            />
          </Box>
          <Text color="gray" dimColor>Enter bestätigen · Escape abbrechen</Text>
        </Box>
      )}

      {mode === 'reschedule-input' && (
        <Box flexDirection="column" borderStyle="round" borderColor="yellow" paddingX={1}>
          <Text color="yellow" bold>Neues Datum (YYYY-MM-DD):</Text>
          <Box>
            <Text color="gray"> › </Text>
            <TextInput
              value={newDate}
              onChange={setNewDate}
              onSubmit={() => void handleReschedule()}
              focus={true}
            />
          </Box>
          <Text color="gray" dimColor>Enter bestätigen · Escape abbrechen</Text>
        </Box>
      )}

      <Box marginTop={1}>
        <Text color="gray" dimColor>
          {menuItems.length > 0 ? '[m] Aktionsmenü · ' : ''}Backspace Zurück
        </Text>
      </Box>
    </Box>
  );
}
