<?php

namespace MintyPHP\App\Module;

use RuntimeException;

/**
 * Publishes module web assets to a runtime web/modules directory.
 */
final class ModuleRuntimeAssetPublisher
{
    /**
     * @param array<string, ModuleManifest> $modules
     * @return array{created: int, updated: int, removed: int, unchanged: int}
     */
    public function publish(string $runtimeModulesDir, array $modules, string $mode = 'symlink'): array
    {
        $normalizedMode = strtolower(trim($mode));
        if ($normalizedMode === '') {
            $normalizedMode = 'symlink';
        }
        if (!in_array($normalizedMode, ['symlink', 'copy'], true)) {
            throw new RuntimeException("Unsupported module asset publish mode '{$mode}'. Use 'symlink' or 'copy'.");
        }

        if (is_link($runtimeModulesDir) && !unlink($runtimeModulesDir)) {
            throw new RuntimeException("Cannot remove existing runtime modules symlink: {$runtimeModulesDir}");
        }
        if (!is_dir($runtimeModulesDir) && !mkdir($runtimeModulesDir, 0775, true) && !is_dir($runtimeModulesDir)) {
            throw new RuntimeException("Cannot create runtime modules directory: {$runtimeModulesDir}");
        }

        $result = ['created' => 0, 'updated' => 0, 'removed' => 0, 'unchanged' => 0];

        $desired = [];
        foreach ($modules as $manifest) {
            if (!$manifest instanceof ModuleManifest) {
                continue;
            }
            $moduleWebDir = rtrim($manifest->basePath, '/') . '/web';
            if (!is_dir($moduleWebDir)) {
                continue;
            }
            $desired[$manifest->id] = $moduleWebDir;
        }

        $entries = scandir($runtimeModulesDir);
        if ($entries === false) {
            throw new RuntimeException("Cannot scan runtime modules directory: {$runtimeModulesDir}");
        }
        foreach ($entries as $entry) {
            if ($entry === '.' || $entry === '..') {
                continue;
            }
            if (isset($desired[$entry])) {
                continue;
            }
            $path = $runtimeModulesDir . '/' . $entry;
            $this->removePath($path);
            $result['removed']++;
        }

        foreach ($desired as $moduleId => $moduleWebDir) {
            $targetPath = $runtimeModulesDir . '/' . $moduleId;
            $targetExists = file_exists($targetPath) || is_link($targetPath);

            if ($targetExists && $normalizedMode === 'symlink' && is_link($targetPath)) {
                $targetReal = realpath($targetPath);
                $sourceReal = realpath($moduleWebDir);
                if ($targetReal !== false && $sourceReal !== false && $targetReal === $sourceReal) {
                    $result['unchanged']++;
                    continue;
                }
            }

            if ($targetExists) {
                $this->removePath($targetPath);
            }

            if ($normalizedMode === 'symlink') {
                if (!@symlink($moduleWebDir, $targetPath)) {
                    throw new RuntimeException(
                        "Failed to symlink module assets for '{$moduleId}' ({$moduleWebDir} -> {$targetPath}). " .
                        "Set APP_MODULE_ASSET_MODE=copy if symlinks are unavailable."
                    );
                }
            } else {
                $this->copyDirectory($moduleWebDir, $targetPath);
            }

            if ($targetExists) {
                $result['updated']++;
            } else {
                $result['created']++;
            }
        }

        return $result;
    }

    private function removePath(string $path): void
    {
        if (is_link($path)) {
            if (!unlink($path)) {
                throw new RuntimeException("Cannot remove symlink: {$path}");
            }
            return;
        }

        if (is_file($path)) {
            if (!unlink($path)) {
                throw new RuntimeException("Cannot remove file: {$path}");
            }
            return;
        }

        if (!is_dir($path)) {
            return;
        }

        $entries = scandir($path);
        if ($entries === false) {
            throw new RuntimeException("Cannot scan directory: {$path}");
        }
        foreach ($entries as $entry) {
            if ($entry === '.' || $entry === '..') {
                continue;
            }
            $this->removePath($path . '/' . $entry);
        }

        if (!rmdir($path)) {
            throw new RuntimeException("Cannot remove directory: {$path}");
        }
    }

    private function copyDirectory(string $sourceDir, string $targetDir): void
    {
        if (!is_dir($sourceDir)) {
            throw new RuntimeException("Source module asset directory not found: {$sourceDir}");
        }
        if (!is_dir($targetDir) && !mkdir($targetDir, 0775, true) && !is_dir($targetDir)) {
            throw new RuntimeException("Cannot create target module asset directory: {$targetDir}");
        }

        $entries = scandir($sourceDir);
        if ($entries === false) {
            throw new RuntimeException("Cannot scan source module asset directory: {$sourceDir}");
        }

        foreach ($entries as $entry) {
            if ($entry === '.' || $entry === '..') {
                continue;
            }

            $source = $sourceDir . '/' . $entry;
            $target = $targetDir . '/' . $entry;

            if (is_link($source)) {
                $linkTarget = readlink($source);
                if ($linkTarget === false || !symlink($linkTarget, $target)) {
                    throw new RuntimeException("Cannot copy symlink '{$source}' to '{$target}'");
                }
                continue;
            }
            if (is_dir($source)) {
                $this->copyDirectory($source, $target);
                continue;
            }
            if (!is_file($source)) {
                continue;
            }
            if (!copy($source, $target)) {
                throw new RuntimeException("Cannot copy file '{$source}' to '{$target}'");
            }
        }
    }
}