<?php

namespace App\Http\Controllers\Api;

use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Log;
use Symfony\Component\HttpFoundation\Response;

class EmailExtractorController extends BaseApiController
{
    /**
     * GET /api/emails
     * Returns JSON: { users: string[], parents: string[] }
     * Pulls emails from users.email and parents.secondparent_email
     */
    public function getEmails()
    {
        try {
            $users = [];
            $parents = [];

            // Fetch users.email (non-null, non-empty)
            $userRows = DB::table('users')->select('email')->get();
            foreach ($userRows as $row) {
                $email = strtolower(trim((string)($row->email ?? '')));
                if ($email !== '' && filter_var($email, FILTER_VALIDATE_EMAIL)) {
                    $users[] = $email;
                }
            }
            // De-duplicate
            $users = array_values(array_unique($users));

            // Fetch parents.secondparent_email (non-null, non-empty)
            $parentRows = DB::table('parents')->select('secondparent_email')->get();
            foreach ($parentRows as $row) {
                $email = strtolower(trim((string)($row->secondparent_email ?? '')));
                if ($email !== '' && filter_var($email, FILTER_VALIDATE_EMAIL)) {
                    $parents[] = $email;
                }
            }
            // De-duplicate
            $parents = array_values(array_unique($parents));

            return $this->success([
                'users'   => $users,
                'parents' => $parents,
            ], 'Emails retrieved successfully');
        } catch (\Throwable $e) {
            Log::error('Email extraction error: ' . $e->getMessage());
            return $this->respondError('Database error: ' . $e->getMessage(), Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * POST /api/compare
     * Accepts multipart/form-data with a CSV file named 'file' (optional),
     * or JSON body with { csvEmails: string[] } (optional).
     * Compares against DB and returns:
     * {
     *   existed: string[],        // in CSV AND in DB
     *   needToAdd: string[],      // in DB BUT NOT in CSV
     *   counts: { csv: number, db: number, users: number, parents: number }
     * }
     */
    public function compare()
    {
        $csvEmails = [];

        // 1) Try read from uploaded file
        if ($this->laravelRequest->hasFile('file')) {
            $file = $this->laravelRequest->file('file');
            if ($file->isValid()) {
                $contents = file_get_contents($file->getRealPath());
                $csvEmails = $this->extractEmailsFromText($contents);
            }
        }

        // 2) Or from JSON body
        if (empty($csvEmails)) {
            $data = $this->payloadData();
            if (isset($data['csvEmails']) && is_array($data['csvEmails'])) {
                $csvEmails = $this->normalizeEmailArray($data['csvEmails']);
            }
        }

        // 3) Compare with DB
        try {
            // Fetch DB emails
            $users = [];
            $parents = [];

            $userRows = DB::table('users')->select('email')->get();
            foreach ($userRows as $row) {
                $e = strtolower(trim((string)($row->email ?? '')));
                if ($e !== '' && filter_var($e, FILTER_VALIDATE_EMAIL)) {
                    $users[] = $e;
                }
            }
            $users = array_values(array_unique($users));

            $parentRows = DB::table('parents')->select('secondparent_email')->get();
            foreach ($parentRows as $row) {
                $e = strtolower(trim((string)($row->secondparent_email ?? '')));
                if ($e !== '' && filter_var($e, FILTER_VALIDATE_EMAIL)) {
                    $parents[] = $e;
                }
            }
            $parents = array_values(array_unique($parents));

            // Sets for comparison
            $csvSet = array_flip(array_values(array_unique($csvEmails)));
            $dbUnion = array_values(array_unique(array_merge($users, $parents)));
            $dbSet = array_flip($dbUnion);

            // existed: in CSV and in DB
            $existed = [];
            foreach ($csvSet as $email => $_) {
                if (isset($dbSet[$email])) {
                    $existed[] = $email;
                }
            }
            sort($existed);

            // needToAdd: in DB but NOT in CSV
            $needToAdd = [];
            foreach ($dbSet as $email => $_) {
                if (!isset($csvSet[$email])) {
                    $needToAdd[] = $email;
                }
            }
            sort($needToAdd);

            return $this->success([
                'existed'   => $existed,
                'needToAdd' => $needToAdd,
                'counts'    => [
                    'csv'     => count($csvEmails),
                    'db'      => count($dbUnion),
                    'users'   => count($users),
                    'parents' => count($parents),
                ],
            ], 'Comparison completed successfully');
        } catch (\Throwable $e) {
            Log::error('Email comparison error: ' . $e->getMessage());
            return $this->respondError('Database error: ' . $e->getMessage(), Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    // Helpers

    private function normalizeEmailArray(array $arr): array
    {
        $out = [];
        foreach ($arr as $e) {
            $email = strtolower(trim((string)$e));
            if ($email !== '' && filter_var($email, FILTER_VALIDATE_EMAIL)) {
                $out[] = $email;
            }
        }
        return array_values(array_unique($out));
    }

    private function extractEmailsFromText(string $text): array
    {
        $pattern = '/[A-Z0-9._%+-]+@[A-Z0-9.-]+\\.[A-Z]{2,}/i';
        preg_match_all($pattern, $text, $matches);
        $emails = $matches[0] ?? [];
        return $this->normalizeEmailArray($emails);
    }
}