/**
 * Refund management routes.
 *
 * Handles refunds for formation orders and compliance service orders
 * when the failure was not the customer's fault.
 *
 * Refund flow:
 *   1. System or admin initiates refund (POST /api/v1/admin/refunds)
 *   2. Admin reviews + approves (PATCH /api/v1/admin/refunds/:id)
 *   3. Admin sends refund via Relay dashboard (manual ACH)
 *   4. Admin marks as sent/confirmed
 *   5. Customer receives email notification at each step
 *
 * Auto-refund triggers (created by the formation worker):
 *   - State portal charged the card but rejected the filing
 *   - Payment went through but automation crashed before filing completed
 *   - Name collision discovered after payment was processed
 */

import { Router } from "express";
import { pool } from "../db.js";
import { requireAdmin } from "../middleware/admin-auth.js";
import { v4 as uuidv4 } from "uuid";

const router = Router();

// =====================================================================
// Admin: Create a refund
// =====================================================================

router.post("/api/v1/admin/refunds", requireAdmin, async (req, res) => {
  try {
    const {
      order_type, order_id, order_number,
      customer_name, customer_email,
      original_amount_cents, refund_amount_cents, refund_type,
      reason_category, reason_detail,
      state_fee_recoverable, refund_method,
      admin_notes,
    } = req.body ?? {};

    if (!order_number || !customer_email || !refund_amount_cents || !reason_category) {
      res.status(400).json({ error: "Missing required fields: order_number, customer_email, refund_amount_cents, reason_category" });
      return;
    }

    const year = new Date().getFullYear();
    const short = uuidv4().split("-")[0]!.toUpperCase();
    const refundNumber = `REF-${year}-${short}`;

    const result = await pool.query(
      `INSERT INTO refunds (
        refund_number, order_type, order_id, order_number,
        customer_name, customer_email,
        original_amount_cents, refund_amount_cents, refund_type,
        reason_category, reason_detail,
        state_fee_recoverable, refund_method,
        admin_notes, requested_by, status
      ) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,'pending')
      RETURNING id, refund_number`,
      [
        refundNumber,
        order_type || "formation",
        order_id || null,
        order_number,
        customer_name || "",
        customer_email,
        original_amount_cents || 0,
        refund_amount_cents,
        refund_type || "full",
        reason_category,
        reason_detail || null,
        state_fee_recoverable || false,
        refund_method || "relay_ach",
        admin_notes || null,
        `admin:${req.admin!.username}`,
      ],
    );

    const refund = result.rows[0];

    // Link refund to the order
    if (order_id) {
      const table = order_type === "formation" ? "formation_orders" : "orders";
      await pool.query(
        `UPDATE ${table} SET refund_id = $1, refunded = FALSE WHERE id = $2`,
        [refund.id, order_id],
      );
    }

    // Log to audit
    if (order_id) {
      await pool.query(
        `INSERT INTO order_audit_log (order_type, order_id, order_number, action, actor_type, actor_id, actor_name, note)
         VALUES ($1, $2, $3, 'refund_initiated', 'admin', $4, $5, $6)`,
        [order_type || "formation", order_id, order_number, req.admin!.id, req.admin!.username,
         `Refund ${refundNumber}: $${(refund_amount_cents / 100).toFixed(2)} — ${reason_category}`],
      );
    }

    res.status(201).json({
      success: true,
      refund_number: refund.refund_number,
      refund_id: refund.id,
      message: "Refund created. Review and approve to process.",
    });
  } catch (err) {
    console.error("[refunds] Create error:", err);
    res.status(500).json({ error: "Could not create refund." });
  }
});

// =====================================================================
// Admin: List refunds
// =====================================================================

router.get("/api/v1/admin/refunds", requireAdmin, async (req, res) => {
  try {
    const status = req.query.status as string || "";
    const limit = Math.min(parseInt(req.query.limit as string, 10) || 50, 200);
    const offset = parseInt(req.query.offset as string, 10) || 0;

    let where = "WHERE 1=1";
    const params: any[] = [];
    let idx = 1;

    if (status) { where += ` AND status = $${idx++}`; params.push(status); }

    const countResult = await pool.query(`SELECT COUNT(*) as total FROM refunds ${where}`, params);

    params.push(limit, offset);
    const result = await pool.query(
      `SELECT * FROM refunds ${where} ORDER BY created_at DESC LIMIT $${idx++} OFFSET $${idx++}`,
      params,
    );

    res.json({
      refunds: result.rows,
      total: parseInt(countResult.rows[0].total, 10),
      limit, offset,
    });
  } catch (err) {
    console.error("[refunds] List error:", err);
    res.status(500).json({ error: "Could not load refunds." });
  }
});

// =====================================================================
// Admin: Get single refund
// =====================================================================

router.get("/api/v1/admin/refunds/:id", requireAdmin, async (req, res) => {
  try {
    const id = parseInt(req.params.id, 10);
    const result = await pool.query("SELECT * FROM refunds WHERE id = $1", [id]);
    if (result.rows.length === 0) {
      res.status(404).json({ error: "Refund not found." });
      return;
    }
    res.json({ refund: result.rows[0] });
  } catch (err) {
    console.error("[refunds] Get error:", err);
    res.status(500).json({ error: "Could not load refund." });
  }
});

// =====================================================================
// Admin: Update refund status (approve, send, confirm, deny)
// =====================================================================

router.patch("/api/v1/admin/refunds/:id", requireAdmin, async (req, res) => {
  try {
    const id = parseInt(req.params.id, 10);
    const { status, admin_notes, relay_transaction_id, denied_reason, refund_method } = req.body ?? {};

    const current = await pool.query("SELECT * FROM refunds WHERE id = $1", [id]);
    if (current.rows.length === 0) {
      res.status(404).json({ error: "Refund not found." });
      return;
    }
    const refund = current.rows[0];

    const updates: string[] = [];
    const params: any[] = [];
    let pIdx = 1;

    if (status) {
      updates.push(`status = $${pIdx++}`); params.push(status);

      if (status === "approved") {
        updates.push(`approved_by = $${pIdx++}`); params.push(req.admin!.id);
        updates.push("approved_at = now()");
      }
      if (status === "sent") {
        updates.push("sent_at = now()");
      }
      if (status === "confirmed") {
        updates.push("confirmed_at = now()");
        // Mark the order as refunded
        if (refund.order_id) {
          const table = refund.order_type === "formation" ? "formation_orders" : "orders";
          await pool.query(`UPDATE ${table} SET refunded = TRUE WHERE id = $1`, [refund.order_id]);
        }
      }
      if (status === "denied") {
        updates.push(`denied_reason = $${pIdx++}`); params.push(denied_reason || "Refund denied");
      }
    }

    if (admin_notes !== undefined) { updates.push(`admin_notes = $${pIdx++}`); params.push(admin_notes); }
    if (relay_transaction_id) { updates.push(`relay_transaction_id = $${pIdx++}`); params.push(relay_transaction_id); }
    if (refund_method) { updates.push(`refund_method = $${pIdx++}`); params.push(refund_method); }

    if (updates.length > 0) {
      updates.push("updated_at = now()");
      params.push(id);
      await pool.query(
        `UPDATE refunds SET ${updates.join(", ")} WHERE id = $${pIdx}`,
        params,
      );
    }

    // Audit log
    if (status && refund.order_id) {
      await pool.query(
        `INSERT INTO order_audit_log (order_type, order_id, order_number, action, from_status, to_status, actor_type, actor_id, actor_name, note)
         VALUES ($1, $2, $3, $4, $5, $6, 'admin', $7, $8, $9)`,
        [refund.order_type, refund.order_id, refund.order_number,
         `refund_${status}`, refund.status, status,
         req.admin!.id, req.admin!.username,
         `Refund ${refund.refund_number}: status → ${status}${admin_notes ? '. ' + admin_notes : ''}`],
      );
    }

    res.json({ success: true, message: `Refund status updated to: ${status || 'updated'}` });
  } catch (err) {
    console.error("[refunds] Update error:", err);
    res.status(500).json({ error: "Could not update refund." });
  }
});

// =====================================================================
// Admin: Dashboard stats for refunds
// =====================================================================

router.get("/api/v1/admin/refunds/stats", requireAdmin, async (req, res) => {
  try {
    const result = await pool.query(`
      SELECT
        COUNT(*) FILTER (WHERE status = 'pending') as pending,
        COUNT(*) FILTER (WHERE status = 'approved') as approved,
        COUNT(*) FILTER (WHERE status = 'processing') as processing,
        COUNT(*) FILTER (WHERE status = 'sent') as sent,
        COUNT(*) FILTER (WHERE status = 'confirmed') as confirmed,
        COUNT(*) FILTER (WHERE status = 'denied') as denied,
        COUNT(*) as total,
        COALESCE(SUM(refund_amount_cents) FILTER (WHERE status IN ('sent','confirmed')), 0) as total_refunded_cents,
        COALESCE(SUM(refund_amount_cents) FILTER (WHERE status = 'pending'), 0) as pending_refund_cents
      FROM refunds
    `);
    res.json({ stats: result.rows[0] });
  } catch (err) {
    console.error("[refunds] Stats error:", err);
    res.status(500).json({ error: "Could not load refund stats." });
  }
});

// =====================================================================
// System: Auto-create refund (called by formation worker on failure)
// =====================================================================

router.post("/api/v1/internal/refunds/auto", async (req, res) => {
  // This endpoint is called internally by the worker when a state charges
  // the card but the filing fails. No admin auth — uses internal secret.
  const secret = req.headers["x-internal-secret"];
  if (!secret || secret !== process.env.WEBHOOK_SECRET) {
    res.status(401).json({ error: "Unauthorized" });
    return;
  }

  try {
    const {
      order_type, order_id, order_number,
      customer_name, customer_email,
      amount_cents, reason_category, reason_detail,
    } = req.body ?? {};

    const year = new Date().getFullYear();
    const short = uuidv4().split("-")[0]!.toUpperCase();
    const refundNumber = `REF-${year}-${short}`;

    const result = await pool.query(
      `INSERT INTO refunds (
        refund_number, order_type, order_id, order_number,
        customer_name, customer_email,
        original_amount_cents, refund_amount_cents, refund_type,
        reason_category, reason_detail,
        requested_by, status
      ) VALUES ($1,$2,$3,$4,$5,$6,$7,$7,'full',$8,$9,'system','pending')
      RETURNING id, refund_number`,
      [refundNumber, order_type || "formation", order_id, order_number,
       customer_name, customer_email, amount_cents,
       reason_category, reason_detail],
    );

    // Create ERPNext issue to alert admin
    console.log(`[refunds] Auto-refund created: ${result.rows[0].refund_number} for ${order_number} — $${(amount_cents / 100).toFixed(2)}`);

    res.status(201).json({
      success: true,
      refund_number: result.rows[0].refund_number,
    });
  } catch (err) {
    console.error("[refunds] Auto-create error:", err);
    res.status(500).json({ error: "Could not create auto-refund." });
  }
});

export default router;