<?php

namespace App\Services;

use App\Exceptions\InceptNebLimitException;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Schema;

class InceptNebAllocation
{
    public const FORM_ID = '1786346682-7ed41cf4-f562-4eb7-8d53-efedd0133f41';
    public const MSL_LIMIT = 10;

    public const TYPES = [
        'robust' => ['label' => 'Robust', 'column' => 'robust_qty'],
        'mini' => ['label' => 'Mini', 'column' => 'mini_qty'],
        'control_d' => ['label' => 'Control D', 'column' => 'control_d_qty'],
    ];

    public function summaryForEmployee($empId)
    {
        $empId = $this->normalizeEmpId($empId);
        $allocation = $empId === '' ? null : DB::table('incept_neb_allocations')->where('emp_id', $empId)->first();
        $usedByType = [];
        if ($empId !== '') {
            $rows = DB::table('incept_neb_usage')
                ->select('nebulizer_type', DB::raw('SUM(qty) as used_qty'))
                ->where('emp_id', $empId)
                ->groupBy('nebulizer_type')
                ->get();
            foreach ($rows as $row) {
                $usedByType[$row->nebulizer_type] = (int) $row->used_qty;
            }
        }

        $types = [];
        foreach (self::TYPES as $key => $meta) {
            $allocated = $allocation ? (int) ($allocation->{$meta['column']} ?? 0) : 0;
            $used = (int) ($usedByType[$key] ?? 0);
            $types[$key] = [
                'label' => $meta['label'],
                'allocated' => $allocated,
                'used' => $used,
                'balance' => max(0, $allocated - $used),
            ];
        }

        return [
            'emp_id' => $allocation->emp_id ?? $empId,
            'emp_name' => $allocation->emp_name ?? '',
            'team' => $allocation->team ?? '',
            'designation' => $allocation->designation ?? '',
            'has_allocation' => (bool) $allocation,
            'types' => $types,
        ];
    }

    public function summaryAll()
    {
        $allocated = [
            'robust' => (int) DB::table('incept_neb_allocations')->sum('robust_qty'),
            'mini' => (int) DB::table('incept_neb_allocations')->sum('mini_qty'),
            'control_d' => (int) DB::table('incept_neb_allocations')->sum('control_d_qty'),
        ];
        $usedByType = [];
        $rows = DB::table('incept_neb_usage')
            ->select('nebulizer_type', DB::raw('SUM(qty) as used_qty'))
            ->groupBy('nebulizer_type')
            ->get();
        foreach ($rows as $row) {
            $usedByType[$row->nebulizer_type] = (int) $row->used_qty;
        }

        $types = [];
        foreach (self::TYPES as $key => $meta) {
            $qty = (int) ($allocated[$key] ?? 0);
            $used = (int) ($usedByType[$key] ?? 0);
            $types[$key] = [
                'label' => $meta['label'],
                'allocated' => $qty,
                'used' => $used,
                'balance' => max(0, $qty - $used),
            ];
        }

        return ['types' => $types];
    }

    public function viewerSeesOrgTotals($formdata)
    {
        $allAccess = $this->formValue($formdata, 'all_data_access');
        if ($allAccess === true || $allAccess === 1 || $allAccess === '1' || $allAccess === 'true') {
            return true;
        }

        $designation = '';
        if (is_object($formdata) && isset($formdata->user_info->designation)) {
            $designation = (string) $formdata->user_info->designation;
        }
        if (trim($designation) === '') {
            $empId = $this->resolveEmpId([], is_object($formdata) ? $formdata : null);
            if ($empId !== '') {
                $allocation = DB::table('incept_neb_allocations')->where('emp_id', $empId)->first();
                $designation = $allocation->designation ?? '';
            }
        }

        return strtoupper(trim($designation)) === 'HO';
    }

    public function withOrgTotals(array $summary, $formdata)
    {
        if (!$this->viewerSeesOrgTotals($formdata)) {
            return $summary;
        }
        $summary['show_org_totals'] = true;
        $summary['org_totals'] = $this->summaryAll();

        return $summary;
    }

    public function mslUsage($mslCode)
    {
        $mslCode = trim((string) $mslCode);
        $used = 0;
        if ($mslCode !== '') {
            $used = (int) DB::table('incept_neb_usage')->where('msl_code', $mslCode)->sum('qty');
        }

        return [
            'msl_code' => $mslCode,
            'used' => $used,
            'limit' => self::MSL_LIMIT,
            'remaining' => max(0, self::MSL_LIMIT - $used),
        ];
    }

    public function resolveEmpIdFromUser($userId)
    {
        $userId = trim((string) $userId);
        if ($userId === '' || !Schema::hasTable('users')) {
            return '';
        }

        $query = DB::table('users');
        $user = (clone $query)->where('user_id', $userId)->first();
        if (!$user) {
            $user = DB::table('users')->where('id', $userId)->first();
        }
        if (!$user) {
            return '';
        }

        foreach (['emp_employee_code', 'employee_code', 'emp_id'] as $column) {
            if (isset($user->{$column}) && trim((string) $user->{$column}) !== '') {
                return $this->normalizeEmpId($user->{$column});
            }
        }

        return '';
    }

    public function resolveEmpId($post, $formdata = null)
    {
        $candidates = [];
        if (is_array($post)) {
            foreach (['incept_emp_id', 'emp_id', 'employee_code'] as $key) {
                if (!empty($post[$key])) {
                    $candidates[] = $post[$key];
                }
            }
            if (!empty($post['user_id'])) {
                $candidates[] = $this->resolveEmpIdFromUser($post['user_id']);
            }
        }
        if (is_object($formdata) && isset($formdata->user_info)) {
            foreach (['employee_code', 'emp_employee_code', 'emp_id'] as $key) {
                if (!empty($formdata->user_info->{$key})) {
                    $candidates[] = $formdata->user_info->{$key};
                }
            }
        }
        if (is_object($formdata) && !empty($formdata->employee_code)) {
            $candidates[] = $formdata->employee_code;
        }
        if (is_object($formdata) && !empty($formdata->user_id)) {
            $candidates[] = $this->resolveEmpIdFromUser($formdata->user_id);
        }

        foreach ($candidates as $candidate) {
            $empId = $this->normalizeEmpId($candidate);
            if ($empId !== '') {
                return $empId;
            }
        }

        return '';
    }

    public function reserveFromSubmission(array $post, $formdata)
    {
        $type = $this->typeKey($post['type_of_nebulizer'] ?? '');
        $qty = (int) ($post['no_of_nebulizer'] ?? 0);
        $mslCode = trim((string) ($post['msl_code'] ?? ''));
        $empId = $this->resolveEmpId($post, $formdata);

        if ($type === null) {
            throw new InceptNebLimitException('Select a nebulizer type.');
        }
        if ($qty < 1) {
            throw new InceptNebLimitException('Enter the number of nebulizers.');
        }
        if ($mslCode === '') {
            throw new InceptNebLimitException('MSL code is required.');
        }
        if ($empId === '') {
            throw new InceptNebLimitException('Employee allocation could not be matched.');
        }

        $locks = [];
        try {
            $locks[] = $this->acquireLock('incept_neb_emp_' . $empId);
            $locks[] = $this->acquireLock('incept_neb_msl_' . $mslCode);

            return DB::transaction(function () use ($empId, $type, $qty, $mslCode) {
                $allocation = DB::table('incept_neb_allocations')->where('emp_id', $empId)->lockForUpdate()->first();
                if (!$allocation) {
                    throw new InceptNebLimitException('No nebulizer allocation is set for employee ' . $empId . '.');
                }

                $column = self::TYPES[$type]['column'];
                $allocated = (int) ($allocation->{$column} ?? 0);
                $used = (int) DB::table('incept_neb_usage')
                    ->where('emp_id', $empId)
                    ->where('nebulizer_type', $type)
                    ->lockForUpdate()
                    ->sum('qty');
                $balance = $allocated - $used;
                if ($qty > $balance) {
                    throw new InceptNebLimitException(
                        'Only ' . max(0, $balance) . ' ' . self::TYPES[$type]['label'] . ' nebulizer(s) are left in your allocation.'
                    );
                }

                $mslUsed = (int) DB::table('incept_neb_usage')->where('msl_code', $mslCode)->lockForUpdate()->sum('qty');
                if (($mslUsed + $qty) > self::MSL_LIMIT) {
                    $remaining = max(0, self::MSL_LIMIT - $mslUsed);
                    throw new InceptNebLimitException(
                        'MSL ' . $mslCode . ' can take ' . $remaining . ' more nebulizer(s). The overall limit is ' . self::MSL_LIMIT . '.'
                    );
                }

                return DB::table('incept_neb_usage')->insertGetId([
                    'emp_id' => $empId,
                    'msl_code' => $mslCode,
                    'nebulizer_type' => $type,
                    'qty' => $qty,
                    'submission_id' => null,
                    'created_at' => date('Y-m-d H:i:s'),
                    'updated_at' => date('Y-m-d H:i:s'),
                ]);
            });
        } finally {
            foreach (array_reverse($locks) as $lock) {
                DB::select('SELECT RELEASE_LOCK(?)', [$lock]);
            }
        }
    }

    public function attachSubmission($usageId, $submissionId)
    {
        if (!$usageId) {
            return;
        }
        DB::table('incept_neb_usage')->where('id', $usageId)->update([
            'submission_id' => (string) $submissionId,
            'updated_at' => date('Y-m-d H:i:s'),
        ]);
    }

    public function release($usageId)
    {
        if (!$usageId) {
            return;
        }
        DB::table('incept_neb_usage')->where('id', $usageId)->delete();
    }

    public function releaseBySubmission($submissionId)
    {
        $submissionId = trim((string) $submissionId);
        if ($submissionId === '') {
            return;
        }
        DB::table('incept_neb_usage')->where('submission_id', $submissionId)->delete();
    }

    public function typeKey($label)
    {
        $value = strtolower(trim((string) $label));
        $value = str_replace([' ', '-'], '_', $value);
        if ($value === 'robust') {
            return 'robust';
        }
        if ($value === 'mini') {
            return 'mini';
        }
        if ($value === 'control_d' || $value === 'controld') {
            return 'control_d';
        }

        return null;
    }

    public function normalizeEmpId($value)
    {
        if (is_int($value) || is_float($value)) {
            if ((float) $value === floor((float) $value)) {
                return (string) (int) $value;
            }
        }
        $value = trim((string) $value);
        $value = str_replace("\xc2\xa0", ' ', $value);
        $value = trim($value);
        if ($value !== '' && is_numeric($value) && strpos($value, '.') !== false) {
            $value = (string) (int) $value;
        }

        return $value;
    }

    private function formValue($formdata, $key)
    {
        if (is_object($formdata) && isset($formdata->{$key})) {
            return $formdata->{$key};
        }
        if (is_array($formdata) && array_key_exists($key, $formdata)) {
            return $formdata[$key];
        }

        return null;
    }

    private function acquireLock($name)
    {
        $name = substr($name, 0, 64);
        $row = DB::selectOne('SELECT GET_LOCK(?, 10) AS locked', [$name]);
        if (!$row || (int) $row->locked !== 1) {
            throw new InceptNebLimitException('Nebulizer allocation is busy. Please try again.');
        }

        return $name;
    }
}