<?php

namespace App\Http\Controllers\Api;

use App\Models\AdditionalCharge;
use App\Models\Configuration;
use App\Models\User;
use App\Models\Invoice;
use Carbon\Carbon;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Event;
use Symfony\Component\HttpFoundation\Response;

class ExtraChargesController extends BaseApiController
{
    protected AdditionalCharge $additionalCharge;
    protected Configuration $config;
    protected User $user;
    protected Invoice $invoice;
    protected ?string $schoolYear;
    protected ?string $semester;

    public function __construct()
    {
        parent::__construct();
        $this->additionalCharge = model(AdditionalCharge::class);
        $this->user = model(User::class);
        $this->invoice = model(Invoice::class);
        $this->config = model(Configuration::class);
        $this->schoolYear = $this->config->getConfig('school_year');
        $this->semester = $this->config->getConfig('semester');
    }

    public function index()
    {
        $year = (string) ($this->request->getGet('school_year') ?? $this->schoolYear ?? '');
        $sem = (string) ($this->request->getGet('semester') ?? $this->semester ?? '');
        $status = $this->request->getGet('status') ?: null;
        $q = trim((string) ($this->request->getGet('q') ?? '')) ?: null;
        $per = (int) ($this->request->getGet('per_page') ?? 50);

        $paginator = $this->additionalCharge->listAllForTerm($year, $sem, $status, $q, $per);

        $meta = [
            'perPage' => $paginator->perPage(),
            'page' => $paginator->currentPage(),
            'total' => $paginator->total(),
            'pageCount' => $paginator->lastPage(),
        ];

        return $this->success([
            'school_year' => $year,
            'semester' => $sem,
            'rows' => $paginator->items(),
            'pager' => $meta,
        ], 'Extra charges retrieved successfully');
    }

    public function show($id = null)
    {
        $charge = $this->additionalCharge->find($id);
        if (!$charge) {
            return $this->respondError('Extra charge not found', Response::HTTP_NOT_FOUND);
        }

        return $this->success($charge->toArray(), 'Extra charge retrieved successfully');
    }

    /**
     * Get parent options for Select2 (with search)
     */
    public function parentOptions()
    {
        $q = trim((string) ($this->request->getGet('q') ?? ''));
        $limit = 20;

        $query = $this->user
            ->select('users.id, users.firstname, users.lastname, users.email')
            ->join('user_roles', 'user_roles.user_id = users.id')
            ->join('roles', 'roles.id = user_roles.role_id')
            ->whereRaw('LOWER(roles.name) = ?', ['parent'])
            ->whereNull('user_roles.deleted_at');

        if ($q !== '') {
            $query->where(function ($builder) use ($q) {
                $builder->where('users.firstname', 'like', "%{$q}%")
                    ->orWhere('users.lastname', 'like', "%{$q}%")
                    ->orWhere('users.email', 'like', "%{$q}%");
            });
        }

        $rows = $query
            ->orderBy('users.lastname', 'ASC')
            ->orderBy('users.firstname', 'ASC')
            ->limit($limit)
            ->findAll();

        $results = array_map(function ($r) {
            $name = trim(($r['lastname'] ?? '') . ', ' . ($r['firstname'] ?? ''));
            $email = $r['email'] ?? '';
            $label = $name !== ',' ? $name : ('User #' . $r['id']);
            if ($email) $label .= ' — ' . $email;
            $label .= ' (ID: ' . $r['id'] . ')';
            return ['id' => (int) $r['id'], 'text' => $label];
        }, $rows);

        return $this->success(['results' => $results], 'Parent options retrieved successfully');
    }

    /**
     * Get invoices for a parent (for Select2)
     */
    public function invoicesForParent()
    {
        $parentId = (int) ($this->request->getGet('parent_id') ?? 0);
        $schoolYear = (string) ($this->request->getGet('school_year') ?? $this->schoolYear ?? '');

        $rows = ($parentId > 0)
            ? ($this->invoice->getInvoicesByUserId($parentId, $schoolYear) ?? [])
            : [];

        $results = array_map(function ($inv) {
            $id = (int) ($inv['id'] ?? 0);
            $num = (string) ($inv['invoice_number'] ?? ('INV-' . $id));
            $status = strtolower((string) ($inv['status'] ?? ''));
            $balance = (float) ($inv['balance'] ?? 0);
            $issue = $inv['issue_date'] ?? null;

            return [
                'id' => $id,
                'invoice_number' => $num,
                'status' => $status,
                'balance' => $balance,
                'issue_date' => $issue,
                'text' => $num
                    . ($status ? ' — ' . ucfirst($status) : '')
                    . ' (Bal: $' . number_format($balance, 2) . ')',
            ];
        }, $rows);

        return $this->success(['results' => $results], 'Invoices retrieved successfully');
    }

    public function store()
    {
        $user = $this->getCurrentUser();
        if (!$user) {
            return $this->respondError('Authentication required', Response::HTTP_UNAUTHORIZED);
        }

        $data = $this->payloadData();
        if (empty($data)) {
            return $this->respondError('Invalid request data', Response::HTTP_BAD_REQUEST);
        }

        $rules = [
            'parent_id' => 'required|integer',
            'title' => 'required|string|min:2',
            'amount' => 'required|numeric',
            'charge_type' => 'required|in:add,deduct',
            'due_date' => 'nullable|date',
            'invoice_id' => 'nullable|integer',
        ];

        $errors = $this->validateRequest($data, $rules);
        if (!empty($errors)) {
            return $this->respondValidationError($errors);
        }

        $invoiceId = !empty($data['invoice_id']) ? (int) $data['invoice_id'] : null;
        $chargeType = (string) $data['charge_type'];

        $amountAbs = round(abs((float) $data['amount']), 2);
        $signedAmount = ($chargeType === 'add') ? $amountAbs : -$amountAbs;

        $payload = [
            'parent_id' => (int) $data['parent_id'],
            'invoice_id' => $invoiceId,
            'school_year' => $data['school_year'] ?? $this->schoolYear,
            'semester' => $data['semester'] ?? $this->semester,
            'charge_type' => $chargeType,
            'title' => trim($data['title']),
            'description' => trim($data['description'] ?? ''),
            'amount' => $signedAmount,
            'due_date' => !empty($data['due_date']) ? $data['due_date'] : null,
            'status' => $invoiceId ? 'applied' : 'pending',
            'created_by' => $user->id,
            'created_at' => Carbon::now('UTC')->toDateTimeString(),
        ];

        try {
            DB::beginTransaction();

            // Get invoice before
            $invoiceBefore = $this->normalizeRow(
                $this->invoice->getInvoicesByParentId($data['parent_id'], $this->schoolYear)
            );

            // Insert charge
            $chargeId = $this->additionalCharge->insert($payload);
            if (!$chargeId) {
                throw new \Exception('Failed to insert charge');
            }

            // Apply to invoice if present
            if ($invoiceId) {
                try {
                    if ($chargeType === 'add') {
                        $this->invoice->applyAdditionalCharge($invoiceId, $amountAbs);
                    } else {
                        $this->invoice->deductAdditionalCharge($invoiceId, $amountAbs);
                    }
                } catch (\Throwable $e) {
                    log_message('error', 'apply/deductAdditionalCharge failed: ' . $e->getMessage());
                    throw $e;
                }
            }

            // Get invoice after
            $invoiceAfter = $this->normalizeRow(
                $this->invoice->getInvoicesByParentId($data['parent_id'], $this->schoolYear)
            );

            // Get parent user info
            $parentUser = $this->user->getUserInfoById($data['parent_id']);

            DB::commit();

            // Build event payload
            $first = $parentUser['first_name'] ?? $parentUser['firstname'] ?? '';
            $last = $parentUser['last_name'] ?? $parentUser['lastname'] ?? '';
            $parentName = trim($first . ' ' . $last);

            $invoiceTotal = $invoiceAfter ? (float) ($invoiceAfter['total_amount'] ?? 0) : 0.0;
            $preBalance = $invoiceBefore ? (float) ($invoiceBefore['balance'] ?? 0) : 0.0;
            $postBalance = $invoiceAfter ? (float) ($invoiceAfter['balance'] ?? 0) : 0.0;

            $eventData = [
                'user_id' => (int) ($parentUser['id'] ?? 0),
                'email' => $parentUser['email'] ?? null,
                'firstname' => $first,
                'lastname' => $last,
                'parentName' => $parentName,
                'school_year' => $payload['school_year'],
                'semester' => $payload['semester'],
                'invoice_id' => $invoiceId,
                'invoice_number' => $invoiceAfter['invoice_number'] ?? ($invoiceId ? 'INV-' . $invoiceId : null),
                'charge_id' => $chargeId,
                'charge_title' => $payload['title'],
                'charge_desc' => $payload['description'],
                'charge_type' => $payload['charge_type'],
                'amount_signed' => $signedAmount,
                'amount_abs' => $amountAbs,
                'due_date' => $payload['due_date'],
                'created_at' => $payload['created_at'],
                'pre_balance' => $preBalance,
                'post_balance' => $postBalance,
                'invoice_total' => $invoiceTotal,
                'portal_link' => url('/login'),
                'invoice_link' => $invoiceId ? url('parent/invoices/view/' . $invoiceId) : url('parent/invoices'),
            ];

            // Dispatch event
            Event::dispatch('extraCharge', [$eventData]);

            return $this->respondCreated([
                'id' => $chargeId,
                'invoice_id' => $invoiceId,
                'parent_id' => (int) $data['parent_id'],
            ], 'Charge recorded successfully');
        } catch (\Throwable $e) {
            DB::rollBack();
            log_message('error', 'Transaction failed in ExtraChargesController::store: ' . $e->getMessage());
            return $this->respondError('Failed to save charge: ' . $e->getMessage(), Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    public function update($id = null)
    {
        $row = $this->additionalCharge->find($id);
        if (!$row) {
            return $this->respondError('Charge not found', Response::HTTP_NOT_FOUND);
        }

        $data = $this->payloadData();
        if (empty($data)) {
            return $this->respondError('Invalid request data', Response::HTTP_BAD_REQUEST);
        }

        $newAmount = isset($data['amount']) ? (float) $data['amount'] : (float) $row['amount'];
        $delta = $newAmount - (float) $row['amount'];

        try {
            DB::beginTransaction();

            // Update the charge
            $this->additionalCharge->update($id, [
                'title' => trim($data['title'] ?? $row['title']),
                'description' => trim($data['description'] ?? $row['description']),
                'amount' => $newAmount,
                'due_date' => $data['due_date'] ?? $row['due_date'],
                'charge_type' => $data['charge_type'] ?? $row['charge_type'],
            ]);

            // If it's already applied on an invoice and the amount changed, reflect the delta
            if ($row['status'] === 'applied' && !empty($row['invoice_id']) && abs($delta) > 0.00001) {
                if ($delta > 0) {
                    $this->invoice->applyAdditionalCharge((int) $row['invoice_id'], $delta);
                } else {
                    $this->invoice->reverseAdditionalCharge((int) $row['invoice_id'], -$delta);
                }
            }

            DB::commit();

            $updated = $this->additionalCharge->find($id);
            return $this->success($updated->toArray(), 'Charge updated successfully');
        } catch (\Throwable $e) {
            DB::rollBack();
            log_message('error', 'Failed to update charge: ' . $e->getMessage());
            return $this->respondError('Failed to update charge', Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * Mark a charge as void and roll back its impact on the invoice if applied.
     */
    public function void($id = null)
    {
        $row = $this->additionalCharge->find((int) $id);
        if (!$row) {
            return $this->respondError('Charge not found', Response::HTTP_NOT_FOUND);
        }

        $invoiceId = (int) ($row['invoice_id'] ?? 0);
        $amountAbs = round(abs((float) ($row['amount'] ?? 0)), 2);
        $chargeType = (string) ($row['charge_type'] ?? 'add');
        $status = (string) ($row['status'] ?? 'pending');

        try {
            DB::beginTransaction();

            if ($status === 'applied' && $invoiceId > 0 && $amountAbs > 0) {
                try {
                    if ($chargeType === 'add') {
                        $this->invoice->reverseAdditionalCharge($invoiceId, $amountAbs);
                    } else {
                        // voiding a deduction -> add back
                        $this->invoice->applyAdditionalCharge($invoiceId, $amountAbs);
                    }
                } catch (\Throwable $e) {
                    log_message('error', 'void(): invoice adjust failed: ' . $e->getMessage());
                    throw $e;
                }
            }

            $this->additionalCharge->update((int) $id, [
                'status' => 'void',
            ]);

            DB::commit();

            return $this->success(null, 'Charge voided successfully');
        } catch (\Throwable $e) {
            DB::rollBack();
            log_message('error', 'Failed to void charge: ' . $e->getMessage());
            return $this->respondError('Failed to void charge', Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * Reverse a previously applied charge: undo invoice impact and return to pending state.
     */
    public function reverse($id = null)
    {
        $row = $this->additionalCharge->find((int) $id);
        if (!$row) {
            return $this->respondError('Charge not found', Response::HTTP_NOT_FOUND);
        }

        $invoiceId = (int) ($row['invoice_id'] ?? 0);
        $amountAbs = round(abs((float) ($row['amount'] ?? 0)), 2);
        $chargeType = (string) ($row['charge_type'] ?? 'add');
        $status = (string) ($row['status'] ?? 'pending');

        if ($status !== 'applied' || $invoiceId <= 0 || $amountAbs <= 0) {
            return $this->respondError('Nothing to reverse', Response::HTTP_BAD_REQUEST);
        }

        try {
            DB::beginTransaction();

            try {
                if ($chargeType === 'add') {
                    $this->invoice->reverseAdditionalCharge($invoiceId, $amountAbs);
                } else {
                    $this->invoice->applyAdditionalCharge($invoiceId, $amountAbs);
                }
            } catch (\Throwable $e) {
                log_message('error', 'reverse(): invoice adjust failed: ' . $e->getMessage());
                throw $e;
            }

            $this->additionalCharge->update((int) $id, [
                'status' => 'pending',
                'invoice_id' => null,
            ]);

            DB::commit();

            return $this->success(null, 'Charge reversed to pending successfully');
        } catch (\Throwable $e) {
            DB::rollBack();
            log_message('error', 'Failed to reverse charge: ' . $e->getMessage());
            return $this->respondError('Failed to reverse charge', Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    public function delete($id = null)
    {
        $charge = $this->additionalCharge->find($id);
        if (!$charge) {
            return $this->respondError('Extra charge not found', Response::HTTP_NOT_FOUND);
        }

        try {
            $charge->delete();
            return $this->success(null, 'Extra charge deleted successfully');
        } catch (\Throwable $e) {
            log_message('error', 'Failed to delete charge: ' . $e->getMessage());
            return $this->respondError('Failed to delete charge', Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * Normalize query result into a single associative row
     */
    private function normalizeRow($row): ?array
    {
        if (!$row) return null;
        if (is_array($row) && isset($row[0]) && is_array($row[0])) {
            return $row[0]; // unwrap first row from a result set
        }
        return is_array($row) ? $row : null;
    }
}