const { outputProgress, formatElapsedTime, estimateRemaining, calculateRate } = require('../metrics/utils/progress');

async function importPurchaseOrders(prodConnection, localConnection) {
  const startTime = Date.now();
  let importHistoryId;

  try {
    // Get last sync info
    const [syncInfo] = await localConnection.query(
      "SELECT last_sync_timestamp FROM sync_status WHERE table_name = 'purchase_orders'"
    );
    const lastSyncTime = syncInfo?.[0]?.last_sync_timestamp || '1970-01-01';

    // Create import history record
    const [historyResult] = await localConnection.query(`
      INSERT INTO import_history (
        table_name, 
        start_time, 
        is_incremental,
        status
      ) VALUES (
        'purchase_orders',
        NOW(),
        ?,
        'running'
      )
    `, [!!syncInfo?.[0]]);
    importHistoryId = historyResult.insertId;

    outputProgress({
      operation: "Starting purchase orders import - Initializing",
      status: "running",
    });

    // Get column names for the insert
    const [columns] = await localConnection.query(`
      SELECT COLUMN_NAME 
      FROM INFORMATION_SCHEMA.COLUMNS 
      WHERE TABLE_NAME = 'purchase_orders'
      ORDER BY ORDINAL_POSITION
    `);
    const columnNames = columns
      .map((col) => col.COLUMN_NAME)
      .filter((name) => name !== "id");

    // First get all relevant PO IDs with basic info - modified for incremental
    const [[{ total }]] = await prodConnection.query(`
      SELECT COUNT(*) as total
      FROM (
        SELECT DISTINCT pop.po_id, pop.pid
        FROM po p 
        FORCE INDEX (idx_date_created)
        JOIN po_products pop ON p.po_id = pop.po_id
        JOIN suppliers s ON p.supplier_id = s.supplierid
        WHERE p.date_ordered >= DATE_SUB(CURRENT_DATE, INTERVAL 5 YEAR)
          AND (p.date_ordered > ? 
          OR p.stamp > ?
          OR p.date_modified > ?)
        UNION
        SELECT DISTINCT r.receiving_id as po_id, rp.pid
        FROM receivings_products rp
        LEFT JOIN receivings r ON r.receiving_id = rp.receiving_id
        WHERE rp.received_date >= DATE_SUB(CURRENT_DATE, INTERVAL 5 YEAR)
          AND (rp.received_date > ?
          OR rp.stamp > ?)
      ) all_items
    `, [lastSyncTime, lastSyncTime, lastSyncTime, lastSyncTime, lastSyncTime]);

    const [poList] = await prodConnection.query(`
      SELECT DISTINCT 
        COALESCE(p.po_id, r.receiving_id) as po_id,
        CASE 
          WHEN p.po_id IS NOT NULL THEN s1.companyname
          WHEN r.supplier_id IS NOT NULL THEN s2.companyname
          ELSE 'No Supplier'
        END as vendor,
        CASE WHEN p.po_id IS NOT NULL THEN DATE(p.date_ordered) END as date,
        CASE WHEN p.po_id IS NOT NULL THEN DATE(p.date_estin) END as expected_date,
        COALESCE(p.status, 50) as status,
        COALESCE(p.short_note, '') as notes,
        COALESCE(p.notes, '') as long_note
      FROM (
        SELECT po_id FROM po 
        WHERE date_ordered >= DATE_SUB(CURRENT_DATE, INTERVAL 5 YEAR)
          AND (date_ordered > ?
          OR stamp > ?
          OR date_modified > ?)
        UNION
        SELECT DISTINCT r.receiving_id as po_id
        FROM receivings r
        JOIN receivings_products rp ON r.receiving_id = rp.receiving_id
        WHERE rp.received_date >= DATE_SUB(CURRENT_DATE, INTERVAL 5 YEAR)
          AND (rp.received_date > ?
          OR rp.stamp > ?)
      ) ids
      LEFT JOIN po p ON ids.po_id = p.po_id
      LEFT JOIN suppliers s1 ON p.supplier_id = s1.supplierid
      LEFT JOIN receivings r ON ids.po_id = r.receiving_id
      LEFT JOIN suppliers s2 ON r.supplier_id = s2.supplierid
      ORDER BY po_id
    `, [lastSyncTime, lastSyncTime, lastSyncTime, lastSyncTime, lastSyncTime]);

    const totalItems = total;
    let processed = 0;
    let recordsAdded = 0;
    let recordsUpdated = 0;

    const BATCH_SIZE = 5000;
    const PROGRESS_INTERVAL = 500;
    let lastProgressUpdate = Date.now();

    outputProgress({
      operation: `Starting purchase orders import - Processing ${totalItems} purchase order items`,
      status: "running",
    });

    for (let i = 0; i < poList.length; i += BATCH_SIZE) {
      const batch = poList.slice(i, Math.min(i + BATCH_SIZE, poList.length));
      const poIds = batch.map(po => po.po_id);

      // Get all products for these POs in one query
      const [poProducts] = await prodConnection.query(`
        SELECT 
          pop.po_id,
          pop.pid,
          pr.itemnumber as sku,
          pop.cost_each as cost_price,
          pop.qty_each as ordered
        FROM po_products pop
        FORCE INDEX (PRIMARY)
        JOIN products pr ON pop.pid = pr.pid
        WHERE pop.po_id IN (?)
      `, [poIds]);

      // Process PO products in smaller sub-batches to avoid packet size issues
      const SUB_BATCH_SIZE = 5000;
      for (let j = 0; j < poProducts.length; j += SUB_BATCH_SIZE) {
        const productBatch = poProducts.slice(j, j + SUB_BATCH_SIZE);
        const productPids = [...new Set(productBatch.map(p => p.pid))];
        const batchPoIds = [...new Set(productBatch.map(p => p.po_id))];

        // Get receivings for this batch
        const [receivings] = await prodConnection.query(`
          SELECT 
            r.po_id,
            rp.pid,
            rp.receiving_id,
            rp.qty_each,
            rp.cost_each,
            DATE(NULLIF(rp.received_date, '0000-00-00 00:00:00')) as received_date,
            rp.received_by,
            CASE 
              WHEN r.po_id IS NULL THEN 2  -- No PO
              WHEN r.po_id IN (?) THEN 0   -- Original PO
              ELSE 1                       -- Different PO
            END as is_alt_po
          FROM receivings_products rp
          LEFT JOIN receivings r ON r.receiving_id = rp.receiving_id
          WHERE rp.pid IN (?)
            AND rp.received_date >= DATE_SUB(CURRENT_DATE, INTERVAL 2 YEAR)
          ORDER BY r.po_id, rp.pid, rp.received_date
        `, [batchPoIds, productPids]);

        // Create maps for this sub-batch
        const poProductMap = new Map();
        productBatch.forEach(product => {
          const key = `${product.po_id}-${product.pid}`;
          poProductMap.set(key, product);
        });

        const receivingMap = new Map();
        const altReceivingMap = new Map();
        const noPOReceivingMap = new Map();
        
        receivings.forEach(receiving => {
          const key = `${receiving.po_id}-${receiving.pid}`;
          if (receiving.is_alt_po === 2) {
            // No PO
            if (!noPOReceivingMap.has(receiving.pid)) {
              noPOReceivingMap.set(receiving.pid, []);
            }
            noPOReceivingMap.get(receiving.pid).push(receiving);
          } else if (receiving.is_alt_po === 1) {
            // Different PO
            if (!altReceivingMap.has(receiving.pid)) {
              altReceivingMap.set(receiving.pid, []);
            }
            altReceivingMap.get(receiving.pid).push(receiving);
          } else {
            // Original PO
            if (!receivingMap.has(key)) {
              receivingMap.set(key, []);
            }
            receivingMap.get(key).push(receiving);
          }
        });

        // Verify PIDs exist
        const [existingPids] = await localConnection.query(
          'SELECT pid FROM products WHERE pid IN (?)',
          [productPids]
        );
        const validPids = new Set(existingPids.map(p => p.pid));

        // Prepare values for this sub-batch
        const values = [];
        let batchProcessed = 0;

        for (const po of batch) {
          const poProducts = Array.from(poProductMap.values())
            .filter(p => p.po_id === po.po_id && validPids.has(p.pid));

          for (const product of poProducts) {
            const key = `${po.po_id}-${product.pid}`;
            const receivingHistory = receivingMap.get(key) || [];
            const altReceivingHistory = altReceivingMap.get(product.pid) || [];
            const noPOReceivingHistory = noPOReceivingMap.get(product.pid) || [];
            
            const received = receivingHistory.reduce((sum, r) => sum + r.qty_each, 0);
            const altReceived = altReceivingHistory.reduce((sum, r) => sum + r.qty_each, 0);
            const noPOReceived = noPOReceivingHistory.reduce((sum, r) => sum + r.qty_each, 0);
            const totalReceived = received + altReceived + noPOReceived;
            
            const receiving_status = !totalReceived ? 1 : // created
                                   totalReceived < product.ordered ? 30 : // partial
                                   40; // full

            const allReceivings = [...receivingHistory];
            if (altReceivingHistory.length > 0) {
              allReceivings.push(...altReceivingHistory);
            }
            if (noPOReceivingHistory.length > 0) {
              allReceivings.push(...noPOReceivingHistory);
            }
            allReceivings.sort((a, b) => new Date(a.received_date) - new Date(b.received_date));

            const firstReceiving = allReceivings[0] || {};
            const lastReceiving = allReceivings[allReceivings.length - 1] || {};

            values.push(columnNames.map(col => {
              switch (col) {
                case 'po_id': return po.po_id;
                case 'vendor': return po.vendor;
                case 'date': return po.date;
                case 'expected_date': return po.expected_date;
                case 'pid': return product.pid;
                case 'sku': return product.sku;
                case 'cost_price': return product.cost_price;
                case 'status': return po.status;
                case 'notes': return po.notes;
                case 'long_note': return po.long_note;
                case 'ordered': return product.ordered;
                case 'received': return totalReceived;
                case 'received_date': return firstReceiving.received_date || null;
                case 'last_received_date': return lastReceiving.received_date || null;
                case 'received_by': return firstReceiving.received_by || null;
                case 'receiving_status': return receiving_status;
                case 'receiving_history': return JSON.stringify(allReceivings.map(r => ({
                  receiving_id: r.receiving_id,
                  qty: r.qty_each,
                  cost: r.cost_each,
                  date: r.received_date,
                  received_by: r.received_by,
                  alt_po: r.is_alt_po
                })));
                default: return null;
              }
            }));
            batchProcessed++;
          }
        }

        if (values.length > 0) {
          const placeholders = values.map(() => 
            `(${Array(columnNames.length).fill("?").join(",")})`
          ).join(",");

          const query = `
            INSERT INTO purchase_orders (${columnNames.join(",")})
            VALUES ${placeholders}
            ON DUPLICATE KEY UPDATE ${columnNames
              .filter((col) => col !== "po_id" && col !== "pid")
              .map((col) => `${col} = VALUES(${col})`)
              .join(",")};
          `;

          const result = await localConnection.query(query, values.flat());
          recordsAdded += result.affectedRows - result.changedRows;
          recordsUpdated += result.changedRows;
        }

        processed += batchProcessed;
        
        // Update progress based on time interval
        const now = Date.now();
        if (now - lastProgressUpdate >= PROGRESS_INTERVAL || processed === totalItems) {
          outputProgress({
            status: "running",
            operation: "Purchase orders import",
            current: processed,
            total: totalItems,
            elapsed: formatElapsedTime((Date.now() - startTime) / 1000),
            remaining: estimateRemaining(startTime, processed, totalItems),
            rate: calculateRate(startTime, processed)
          });
          lastProgressUpdate = now;
        }
      }
    }

    // After successful import, update sync status
    await localConnection.query(`
      INSERT INTO sync_status (table_name, last_sync_timestamp)
      VALUES ('purchase_orders', NOW())
      ON DUPLICATE KEY UPDATE last_sync_timestamp = NOW()
    `);

    // Update import history with final stats
    const endTime = Date.now();
    const durationSeconds = Math.round((endTime - startTime) / 1000);
    
    await localConnection.query(`
      UPDATE import_history 
      SET 
        end_time = NOW(),
        duration_seconds = ?,
        records_added = ?,
        records_updated = ?,
        status = 'completed',
        additional_info = JSON_OBJECT(
          'total_processed', ?,
          'last_sync_time', ?,
          'next_sync_time', NOW()
        )
      WHERE id = ?
    `, [durationSeconds, recordsAdded, recordsUpdated, totalItems, lastSyncTime, importHistoryId]);

    return {
      status: "complete",
      totalImported: totalItems,
      recordsAdded,
      recordsUpdated,
      durationSeconds,
      incrementalUpdate: !!syncInfo?.[0]
    };

  } catch (error) {
    // Update import history with error
    if (importHistoryId) {
      await localConnection.query(`
        UPDATE import_history 
        SET 
          end_time = NOW(),
          duration_seconds = ?,
          status = 'failed',
          error_message = ?
        WHERE id = ?
      `, [Math.round((Date.now() - startTime) / 1000), error.message, importHistoryId]);
    }
    
    outputProgress({
      operation: "Purchase orders import failed",
      status: "error",
      error: error.message,
    });
    throw error;
  }
}

module.exports = importPurchaseOrders;