<?php

namespace App\Services;

use Illuminate\Support\Facades\Log;

/**
 * Manages per-company system crontab entries for scheduled Artisan commands.
 *
 * Each entry is tagged with a unique inline comment (marker) so it can be
 * found, updated, or removed later without affecting other cron lines.
 */
class CronJobService
{
    /** Unique prefix embedded at the end of every cron line we own */
    const MARKER_PREFIX = '# hatif-missed-calls-alert-company-';

    // ─────────────────────────────────────────────────────────────
    //  Public API
    // ─────────────────────────────────────────────────────────────

    /**
     * Add or update the missed-calls alert cron job for a company.
     *
     * @param  int  $companyId
     * @param  int  $minutes   Look-back window AND scheduling interval (1-1440)
     * @return bool            true on success
     */
    public static function upsertMissedCallsAlert(int $companyId, int $minutes): bool
    {
        $minutes = max(1, $minutes);
        $marker  = self::marker($companyId);

        $phpBin  = PHP_BINARY;
        $artisan = base_path('artisan');
        $expr    = self::cronExpression($minutes);

        // e.g.  */10 * * * * /usr/bin/php /var/www/ccsystem/artisan missed-calls:alert --company-id=1 >> /dev/null 2>&1 # hatif-missed-calls-alert-company-1
        $newLine = "{$expr} {$phpBin} {$artisan} missed-calls:alert --company-id={$companyId} >> /dev/null 2>&1 {$marker}";

        try {
            $result = self::upsertLine($marker, $newLine);
            if ($result) {
                Log::info("CronJobService: upserted missed-calls alert cron for company {$companyId} every {$minutes} min.");
            } else {
                Log::warning("CronJobService: crontab install returned non-zero for company {$companyId}.");
            }
            return $result;
        } catch (\Throwable $e) {
            Log::error('CronJobService: upsert failed', [
                'company_id' => $companyId,
                'error'      => $e->getMessage(),
            ]);
            return false;
        }
    }

    /**
     * Remove the missed-calls alert cron job for a company.
     *
     * @param  int  $companyId
     * @return bool
     */
    public static function removeMissedCallsAlert(int $companyId): bool
    {
        $marker = self::marker($companyId);

        try {
            $result = self::removeLine($marker);
            if ($result) {
                Log::info("CronJobService: removed missed-calls alert cron for company {$companyId}.");
            }
            return $result;
        } catch (\Throwable $e) {
            Log::error('CronJobService: remove failed', [
                'company_id' => $companyId,
                'error'      => $e->getMessage(),
            ]);
            return false;
        }
    }

    /**
     * Check whether a cron entry exists for the given company.
     */
    public static function exists(int $companyId): bool
    {
        $marker = self::marker($companyId);
        $lines  = self::readCrontab();

        foreach ($lines as $line) {
            if (str_contains($line, $marker)) {
                return true;
            }
        }

        return false;
    }

    // ─────────────────────────────────────────────────────────────
    //  Internal helpers
    // ─────────────────────────────────────────────────────────────

    private static function marker(int $companyId): string
    {
        return self::MARKER_PREFIX . $companyId;
    }

    /**
     * Build a valid cron expression for "every N minutes".
     * Minutes must be a divisor-friendly value; for values that don't divide
    * evenly into 60 we fall back to the slash-step cron syntax, which is
    * universally supported.
     */
    private static function cronExpression(int $minutes): string
    {
        if ($minutes === 1) {
            return '* * * * *';
        }
        return "*/{$minutes} * * * *";
    }

    /** Read the current crontab lines for the running user */
    private static function readCrontab(): array
    {
        exec('crontab -l 2>/dev/null', $lines);
        return is_array($lines) ? $lines : [];
    }

    /** Install an array of lines as the new crontab */
    private static function installCrontab(array $lines): bool
    {
        // Ensure file ends with a newline — required by POSIX
        $content = implode("\n", $lines);
        if ($content !== '' && substr($content, -1) !== "\n") {
            $content .= "\n";
        }

        $tmp = tempnam(sys_get_temp_dir(), 'hatif_cron_');
        file_put_contents($tmp, $content);

        exec("crontab {$tmp}", $output, $exitCode);

        @unlink($tmp);

        return $exitCode === 0;
    }

    private static function upsertLine(string $marker, string $newLine): bool
    {
        // Remove any existing entry with this marker, then append the new one
        $lines   = self::readCrontab();
        $filtered = array_values(
            array_filter($lines, fn ($l) => !str_contains($l, $marker))
        );
        $filtered[] = $newLine;

        return self::installCrontab($filtered);
    }

    private static function removeLine(string $marker): bool
    {
        $lines    = self::readCrontab();
        $filtered = array_values(
            array_filter($lines, fn ($l) => !str_contains($l, $marker))
        );

        // Nothing changed — treat as success
        if (count($filtered) === count($lines)) {
            return true;
        }

        return self::installCrontab($filtered);
    }
}