<?php

declare(strict_types=1);

namespace App\Config;

use RecursiveDirectoryIterator;
use RecursiveIteratorIterator;
use SplFileInfo;

final readonly class CorePatternAuditProvider
{
    public function __construct(
        private string $projectDir,
        private GovernanceConfig $governanceConfig
    ) {
    }

    /**
     * @return array<string, mixed>
     */
    public function audit(bool $includeReviewFindings = false): array
    {
        $sourceRoots = $this->governanceConfig->getCorePatternAuditSourceRoots();
        $excludedPathPrefixes = $this->governanceConfig->getCorePatternAuditExcludedPathPrefixes();
        $excludedPathPatterns = $this->governanceConfig->getCorePatternAuditExcludedPathPatterns();
        $warningPathPrefixes = $this->governanceConfig->getCorePatternAuditWarningPathPrefixes();
        $suspiciousCalls = $this->governanceConfig->getCorePatternAuditSuspiciousCalls();
        $domainMarkers = $this->governanceConfig->getCorePatternAuditDomainMarkerTerms();
        $allowedLiteralPatterns = $this->governanceConfig->getCorePatternAuditAllowedLiteralPatterns();
        $maxSnippetLength = $this->governanceConfig->getCorePatternAuditMaxSnippetLength();

        $sourceFiles = $this->collectSourceFiles($sourceRoots);
        $skippedFiles = [];
        $warningFindings = [];
        $reviewFindings = [];

        foreach ($sourceFiles as $relativePath => $absolutePath) {
            if ($this->isExcludedPath($relativePath, $excludedPathPrefixes, $excludedPathPatterns)) {
                $skippedFiles[] = $relativePath;
                continue;
            }

            $content = file_get_contents($absolutePath);
            if (!is_string($content)) {
                continue;
            }

            $lines = preg_split('/\R/u', $content) ?: [];
            foreach ($lines as $index => $line) {
                $calls = $this->matchingCalls((string) $line, $suspiciousCalls);
                if ($calls === []) {
                    continue;
                }

                $markers = $this->matchingMarkersInStringLiterals((string) $line, $domainMarkers);
                if ($markers !== [] && $this->isAllowedLiteralFinding($relativePath, (string) $line, $allowedLiteralPatterns)) {
                    continue;
                }

                $severity = $markers !== [] && $this->isWarningPath($relativePath, $warningPathPrefixes)
                    ? 'WARN'
                    : 'REVIEW';
                $finding = [
                    'severity' => $severity,
                    'path' => $relativePath,
                    'line' => $index + 1,
                    'calls' => $calls,
                    'markers' => $markers,
                    'snippet' => $this->compactSnippet((string) $line, $maxSnippetLength),
                ];

                if ($severity === 'WARN') {
                    $warningFindings[] = $finding;
                } elseif ($includeReviewFindings) {
                    $reviewFindings[] = $finding;
                }
            }
        }

        $status = $warningFindings === [] ? 'OK' : 'WARN';

        return [
            'status' => $status,
            'summary' => [
                'source_files' => count($sourceFiles),
                'scanned_files' => count($sourceFiles) - count($skippedFiles),
                'skipped_files' => count($skippedFiles),
                'warning_findings' => count($warningFindings),
                'review_findings' => count($reviewFindings),
                'total_reported_findings' => count($warningFindings) + count($reviewFindings),
            ],
            'warnings' => $this->buildWarnings($warningFindings),
            'warning_findings' => $warningFindings,
            'review_findings' => $reviewFindings,
            'skipped_files' => $skippedFiles,
        ];
    }

    /**
     * @param string[] $sourceRoots
     * @return array<string, string>
     */
    private function collectSourceFiles(array $sourceRoots): array
    {
        $files = [];

        foreach ($sourceRoots as $sourceRoot) {
            $sourceRoot = trim($sourceRoot, '/');
            if ($sourceRoot === '') {
                continue;
            }

            $absoluteRoot = $this->projectDir . '/' . $sourceRoot;
            if (!is_dir($absoluteRoot)) {
                continue;
            }

            $iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($absoluteRoot));
            foreach ($iterator as $file) {
                if (!$file instanceof SplFileInfo || !$file->isFile()) {
                    continue;
                }

                if ($file->getExtension() !== 'php') {
                    continue;
                }

                $absolutePath = $file->getPathname();
                $relativePath = $this->relativePath($absolutePath);
                $files[$relativePath] = $absolutePath;
            }
        }

        ksort($files);

        return $files;
    }

    /**
     * @param string[] $prefixes
     * @param string[] $patterns
     */
    private function isExcludedPath(string $relativePath, array $prefixes, array $patterns): bool
    {
        foreach ($prefixes as $prefix) {
            $prefix = trim($prefix);
            if ($prefix !== '' && str_starts_with($relativePath, $prefix)) {
                return true;
            }
        }

        foreach ($patterns as $pattern) {
            if (@preg_match($pattern, $relativePath) === 1) {
                return true;
            }
        }

        return false;
    }

    /** @param string[] $prefixes */
    private function isWarningPath(string $relativePath, array $prefixes): bool
    {
        foreach ($prefixes as $prefix) {
            $prefix = trim($prefix);
            if ($prefix !== '' && str_starts_with($relativePath, $prefix)) {
                return true;
            }
        }

        return false;
    }

    /**
     * @param string[] $calls
     * @return string[]
     */
    private function matchingCalls(string $line, array $calls): array
    {
        $matches = [];
        foreach ($calls as $call) {
            $call = trim($call);
            if ($call === '') {
                continue;
            }

            if (str_contains($line, $call . '(')) {
                $matches[] = $call;
            }
        }

        return array_values(array_unique($matches));
    }

    /**
     * @param string[] $markers
     * @return string[]
     */
    private function matchingMarkersInStringLiterals(string $line, array $markers): array
    {
        $literals = $this->extractStringLiterals($line);
        if ($literals === []) {
            return [];
        }

        $normalizedLiterals = mb_strtolower(implode("\n", $literals), 'UTF-8');
        $matches = [];

        foreach ($markers as $marker) {
            $marker = mb_strtolower(trim($marker), 'UTF-8');
            if ($marker === '') {
                continue;
            }

            if (str_contains($normalizedLiterals, $marker)) {
                $matches[] = $marker;
            }
        }

        return array_values(array_unique($matches));
    }

    /**
     * @return string[]
     */
    private function extractStringLiterals(string $line): array
    {
        $literals = [];
        $length = strlen($line);

        for ($i = 0; $i < $length; $i++) {
            $quote = $line[$i];
            if ($quote !== "'" && $quote !== '"') {
                continue;
            }

            $buffer = '';
            for ($j = $i + 1; $j < $length; $j++) {
                $char = $line[$j];
                if ($char === '\\') {
                    if ($j + 1 < $length) {
                        $buffer .= $line[$j + 1];
                        $j++;
                    }
                    continue;
                }

                if ($char === $quote) {
                    $literals[] = $buffer;
                    $i = $j;
                    break;
                }

                $buffer .= $char;
            }
        }

        return $literals;
    }

    /**
     * @param array<int, array{path:string, pattern:string, reason:string}> $allowedLiteralPatterns
     */
    private function isAllowedLiteralFinding(string $relativePath, string $line, array $allowedLiteralPatterns): bool
    {
        foreach ($allowedLiteralPatterns as $allowed) {
            $pathPrefix = trim($allowed['path']);
            $pattern = trim($allowed['pattern']);
            if ($pathPrefix === '' || $pattern === '') {
                continue;
            }

            if (!str_starts_with($relativePath, $pathPrefix)) {
                continue;
            }

            if (@preg_match($pattern, $line) === 1) {
                return true;
            }
        }

        return false;
    }

    private function relativePath(string $absolutePath): string
    {
        $projectDir = rtrim($this->projectDir, '/') . '/';
        if (str_starts_with($absolutePath, $projectDir)) {
            return str_replace('\\', '/', substr($absolutePath, strlen($projectDir)));
        }

        return str_replace('\\', '/', $absolutePath);
    }

    private function compactSnippet(string $line, int $maxLength): string
    {
        $snippet = trim(preg_replace('/\s+/u', ' ', $line) ?? $line);
        if ($maxLength < 20 || mb_strlen($snippet, 'UTF-8') <= $maxLength) {
            return $snippet;
        }

        return mb_substr($snippet, 0, $maxLength - 3, 'UTF-8') . '...';
    }

    /**
     * @param array<int, array<string, mixed>> $warningFindings
     * @return string[]
     */
    private function buildWarnings(array $warningFindings): array
    {
        if ($warningFindings === []) {
            return [];
        }

        return [
            sprintf(
                'Core pattern audit found %d warning finding(s). Review whether these domain-sensitive patterns belong in YAML-backed configuration.',
                count($warningFindings)
            ),
        ];
    }
}