<?php

declare(strict_types=1);

use App\Framework\Database\Indexing\UnusedIndexDetector;
use App\Framework\Database\Indexing\IndexAnalyzer;
use App\Framework\Database\Indexing\IndexUsageTracker;
use App\Framework\Database\PdoConnection;

describe('UnusedIndexDetector', function () {
    beforeEach(function () {
        $pdo = new PDO('sqlite::memory:');
        $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

        $pdo->exec('
            CREATE TABLE products (
                id INTEGER PRIMARY KEY,
                name TEXT UNIQUE,
                category TEXT,
                price REAL,
                stock INTEGER,
                created_at TEXT
            )
        ');

        $pdo->exec('CREATE INDEX idx_products_category ON products(category)');
        $pdo->exec('CREATE INDEX idx_products_price ON products(price)');
        $pdo->exec('CREATE INDEX idx_products_stock ON products(stock)');
        $pdo->exec('CREATE INDEX idx_products_category_price ON products(category, price)');

        $connection = new PdoConnection($pdo, 'sqlite');
        $analyzer = new IndexAnalyzer($connection);
        $cache = new \App\Framework\Cache\Driver\InMemoryCache();
        $usageTracker = new IndexUsageTracker($cache, $analyzer);

        $this->detector = new UnusedIndexDetector($analyzer, $usageTracker);
        $this->tableName = 'products';
    });

    it('finds unused indexes', function () {
        $unusedIndexes = $this->detector->findUnusedIndexes($this->tableName);

        expect($unusedIndexes)->toBeArray();
        // Since we haven't tracked any usage, all non-unique indexes should be marked as unused
        expect(count($unusedIndexes))->toBeGreaterThan(0);
    });

    it('detects duplicate indexes', function () {
        // Create duplicate index in test
        // (In real scenario, we'd have actual duplicates)
        $duplicates = $this->detector->findDuplicateIndexes($this->tableName);

        expect($duplicates)->toBeArray();
    });

    it('finds redundant indexes (prefix pattern)', function () {
        $redundant = $this->detector->findRedundantIndexes($this->tableName);

        expect($redundant)->toBeArray();

        // idx_products_category is redundant with idx_products_category_price
        // because category is a prefix of [category, price]
        if (!empty($redundant)) {
            expect($redundant[0])->toHaveKey('redundant_index');
            expect($redundant[0])->toHaveKey('covered_by');
        }
    });

    it('generates comprehensive unused index report', function () {
        $report = $this->detector->getUnusedIndexReport($this->tableName);

        expect($report)->toHaveKey('unused');
        expect($report)->toHaveKey('duplicates');
        expect($report)->toHaveKey('redundant');
        expect($report)->toHaveKey('total_removable');
        expect($report)->toHaveKey('estimated_space_savings');

        expect($report['unused'])->toBeArray();
        expect($report['total_removable'])->toBeInt();
    });

    it('generates DROP statements for unused indexes', function () {
        $statements = $this->detector->generateDropStatements($this->tableName);

        expect($statements)->toBeArray();

        foreach ($statements as $statement) {
            expect($statement)->toContain('DROP INDEX');
            expect($statement)->toContain('ON products');
        }
    });

    it('never suggests dropping PRIMARY or UNIQUE indexes', function () {
        $unusedIndexes = $this->detector->findUnusedIndexes($this->tableName);

        // Filter for any PRIMARY or UNIQUE suggestions
        $primaryOrUnique = array_filter($unusedIndexes, function ($index) {
            return str_contains(strtolower($index['index_name']), 'primary') ||
                   str_contains(strtolower($index['index_name']), 'unique');
        });

        expect($primaryOrUnique)->toBeEmpty();
    });

    it('estimates space savings correctly', function () {
        $report = $this->detector->getUnusedIndexReport($this->tableName);

        expect($report['estimated_space_savings'])->toBeString();
        expect($report['estimated_space_savings'])->toMatch('/(MB|GB|< 1 MB)/');
    });
});