<?php

namespace App\Services;

use App\Models\Job;
use App\Models\JobCategory;
use Illuminate\Support\Facades\Log;

class JobEnrichmentService
{
    /**
     * Category keywords mapping
     */
    private array $categoryKeywords = [
        'Software Development' => ['software', 'developer', 'engineer', 'programming', 'coding', 'web', 'mobile', 'frontend', 'backend', 'fullstack', 'full-stack'],
        'Data Science' => ['data', 'analytics', 'scientist', 'machine learning', 'ml', 'ai', 'artificial intelligence', 'statistician'],
        'Design' => ['designer', 'ux', 'ui', 'graphic', 'creative', 'figma', 'sketch', 'product design'],
        'Marketing' => ['marketing', 'seo', 'social media', 'content', 'growth', 'digital marketing', 'brand'],
        'Sales' => ['sales', 'account executive', 'business development', 'account manager', 'sales representative'],
        'Customer Support' => ['support', 'customer service', 'help desk', 'technical support', 'customer success'],
        'Human Resources' => ['hr', 'human resources', 'recruiter', 'talent', 'recruiting'],
        'Finance' => ['finance', 'accountant', 'accounting', 'financial', 'controller', 'analyst'],
        'Operations' => ['operations', 'logistics', 'supply chain', 'project manager', 'program manager'],
        'DevOps' => ['devops', 'infrastructure', 'cloud', 'aws', 'kubernetes', 'docker', 'sre'],
        'Product Management' => ['product manager', 'product owner', 'product lead'],
        'Quality Assurance' => ['qa', 'quality', 'testing', 'test engineer', 'sdet'],
        'Writing' => ['writer', 'content writer', 'copywriter', 'technical writer', 'editor'],
    ];

    /**
     * Auto-categorize a job based on title and description
     */
    public function categorizeJob(Job $job): ?JobCategory
    {
        if ($job->job_category_id) {
            return $job->category;
        }

        $text = strtolower($job->title . ' ' . $job->description);

        foreach ($this->categoryKeywords as $categoryName => $keywords) {
            foreach ($keywords as $keyword) {
                if (str_contains($text, $keyword)) {
                    $category = JobCategory::firstOrCreate(
                        ['slug' => \Str::slug($categoryName)],
                        ['name' => $categoryName, 'description' => "Jobs related to {$categoryName}"]
                    );

                    $job->update(['job_category_id' => $category->id]);

                    Log::debug("Auto-categorized job #{$job->id} as '{$categoryName}'");

                    return $category;
                }
            }
        }

        return null;
    }

    /**
     * Enrich job with additional data
     */
    public function enrichJob(Job $job): void
    {
        // Auto-categorize if not categorized
        if (!$job->job_category_id) {
            $this->categorizeJob($job);
        }

        // Detect if remote from title/description
        if (!$job->remote_allowed) {
            $this->detectRemote($job);
        }

        // Parse salary if not set
        if (!$job->salary_min && !$job->salary_max) {
            $this->parseSalaryFromDescription($job);
        }

        // Infer experience level if not set
        if (!$job->experience_level) {
            $this->inferExperienceLevel($job);
        }
    }

    /**
     * Detect if job is remote based on title/description
     */
    private function detectRemote(Job $job): void
    {
        $text = strtolower($job->title . ' ' . $job->description . ' ' . ($job->location ?? ''));
        $remoteKeywords = ['remote', 'work from home', 'wfh', 'telecommute', 'distributed', 'anywhere'];

        foreach ($remoteKeywords as $keyword) {
            if (str_contains($text, $keyword)) {
                $job->update(['remote_allowed' => true]);
                Log::debug("Detected remote job #{$job->id}");
                return;
            }
        }
    }

    /**
     * Try to parse salary from description
     */
    private function parseSalaryFromDescription(Job $job): void
    {
        $description = $job->description;

        // Match patterns like $50,000-$80,000, $50k-80k, 50-80k, etc.
        $patterns = [
            '/\$?([\d,]+)k?\s*-\s*\$?([\d,]+)k?/i',
            '/salary:\s*\$?([\d,]+)k?\s*-\s*\$?([\d,]+)k?/i',
            '/compensation:\s*\$?([\d,]+)k?\s*-\s*\$?([\d,]+)k?/i',
        ];

        foreach ($patterns as $pattern) {
            if (preg_match($pattern, $description, $matches)) {
                $min = (float) str_replace(',', '', $matches[1]);
                $max = (float) str_replace(',', '', $matches[2]);

                // If values look like they're in 'k' format (e.g., 50 instead of 50000)
                if ($min < 1000) {
                    $min *= 1000;
                    $max *= 1000;
                }

                $job->update([
                    'salary_min' => $min,
                    'salary_max' => $max,
                ]);

                Log::debug("Parsed salary for job #{$job->id}: {$min}-{$max}");
                return;
            }
        }
    }

    /**
     * Infer experience level from title/description
     */
    private function inferExperienceLevel(Job $job): void
    {
        $text = strtolower($job->title);

        $levelKeywords = [
            'entry' => ['junior', 'entry', 'associate', 'intern', 'graduate', 'trainee'],
            'mid' => ['mid', 'intermediate', 'regular'],
            'senior' => ['senior', 'sr', 'lead developer', 'staff'],
            'lead' => ['lead', 'principal', 'architect', 'head of'],
            'executive' => ['director', 'vp', 'vice president', 'chief', 'cto', 'ceo', 'cfo', 'coo'],
        ];

        foreach ($levelKeywords as $level => $keywords) {
            foreach ($keywords as $keyword) {
                if (str_contains($text, $keyword)) {
                    $job->update(['experience_level' => $level]);
                    Log::debug("Inferred experience level for job #{$job->id}: {$level}");
                    return;
                }
            }
        }

        // Default to mid-level if no keywords found
        $job->update(['experience_level' => 'mid']);
    }

    /**
     * Batch enrich multiple jobs
     */
    public function enrichJobs(int $batchSize = 100): int
    {
        $jobs = Job::whereNull('job_category_id')
            ->orWhereNull('experience_level')
            ->limit($batchSize)
            ->get();

        $enrichedCount = 0;

        foreach ($jobs as $job) {
            try {
                $this->enrichJob($job);
                $enrichedCount++;
            } catch (\Exception $e) {
                Log::error("Failed to enrich job #{$job->id}: " . $e->getMessage());
            }
        }

        return $enrichedCount;
    }

    /**
     * Normalize salary to USD (if we had currency conversion)
     */
    public function normalizeSalary(Job $job): void
    {
        // Placeholder for currency conversion logic
        // Would use an API like exchangerate-api.com or similar

        if ($job->salary_currency !== 'USD') {
            // Convert to USD
            // $job->update(['salary_min' => $converted, 'salary_max' => $converted]);
        }
    }
}