<?php

declare(strict_types=1);

namespace Tests\Unit;

use PHPUnit\Framework\Attributes\Test;
use RecursiveDirectoryIterator;
use RecursiveIteratorIterator;
use SplFileInfo;
use Tests\TestCase;

/**
 * The three languages have to say the same things.
 *
 * A key present in one file and absent from another does not fail anywhere: it
 * renders as the raw key — `panel.widgets.stats.projects` — on a screen nobody
 * is looking at in that language. It is the kind of fault that only ever gets
 * found by a user, which is why it is worth a test.
 */
class TranslationCatalogueTest extends TestCase
{
    /**
     * @return array<int, string>
     */
    protected function locales(): array
    {
        return array_keys((array) config('locales.supported'));
    }

    /**
     * Every leaf of a translation file, as dotted keys.
     *
     * @param  array<string, mixed>  $translations
     * @return array<int, string>
     */
    protected function flatten(array $translations, string $prefix = ''): array
    {
        $keys = [];

        foreach ($translations as $key => $value) {
            $path = $prefix === '' ? (string) $key : "{$prefix}.{$key}";

            if (is_array($value)) {
                $keys = [...$keys, ...$this->flatten($value, $path)];

                continue;
            }

            $keys[] = $path;
        }

        return $keys;
    }

    /**
     * @return array<string, array<string, array<int, string>>>
     */
    protected function catalogue(): array
    {
        $catalogue = [];

        foreach ($this->locales() as $locale) {
            foreach (glob(lang_path("{$locale}/*.php")) ?: [] as $file) {
                $catalogue[basename($file)][$locale] = $this->flatten(require $file);
            }
        }

        return $catalogue;
    }

    #[Test]
    public function every_language_carries_the_same_keys(): void
    {
        $missing = [];

        foreach ($this->catalogue() as $file => $byLocale) {
            $everyKey = array_unique(array_merge(...array_values($byLocale)));

            foreach ($this->locales() as $locale) {
                foreach (array_diff($everyKey, $byLocale[$locale] ?? []) as $key) {
                    $missing[] = "[{$locale}] {$file} :: {$key}";
                }
            }
        }

        $this->assertSame([], $missing, "Untranslated keys:\n".implode("\n", $missing));
    }

    #[Test]
    public function no_translation_is_left_empty(): void
    {
        $empty = [];

        foreach ($this->locales() as $locale) {
            foreach (glob(lang_path("{$locale}/*.php")) ?: [] as $file) {
                foreach (require $file as $key => $value) {
                    foreach ($this->leaves($value, (string) $key) as $path => $text) {
                        if (trim((string) $text) === '') {
                            $empty[] = "[{$locale}] ".basename($file)." :: {$path}";
                        }
                    }
                }
            }
        }

        $this->assertSame([], $empty, "Empty translations:\n".implode("\n", $empty));
    }

    /**
     * Every key the application actually asks for exists.
     *
     * The mirror image of the test above: that one catches a key translated in
     * one language and forgotten in another, this one catches a key nobody
     * translated at all.
     */
    #[Test]
    public function every_key_the_code_uses_has_a_translation(): void
    {
        $default = (string) config('locales.default');
        $missing = [];

        foreach ($this->sourceFiles() as $file) {
            $source = (string) file_get_contents($file->getPathname());

            preg_match_all(
                '/(?:__|trans_choice)\(\s*[\'"]([a-z0-9_]+\.[a-z0-9_.\-]+)[\'"]/i',
                $source,
                $matches,
            );

            foreach ($matches[1] as $key) {
                [$group] = explode('.', $key, 2);

                // Keys belonging to a package (`filament-panels::…`) or built
                // dynamically are not this test's business.
                if (! file_exists(lang_path("{$default}/{$group}.php"))) {
                    continue;
                }

                if (! is_string(__($key)) || __($key) === $key) {
                    $missing[] = $key.'  ('.str_replace(base_path().'/', '', $file->getPathname()).')';
                }
            }
        }

        $this->assertSame([], array_unique($missing), "Keys with no translation:\n".implode("\n", array_unique($missing)));
    }

    /**
     * @return array<int, SplFileInfo>
     */
    protected function sourceFiles(): array
    {
        $files = [];

        foreach ([app_path(), resource_path('views')] as $directory) {
            /** @var SplFileInfo $file */
            foreach (new RecursiveIteratorIterator(new RecursiveDirectoryIterator($directory)) as $file) {
                if ($file->isFile() && in_array($file->getExtension(), ['php'], true)) {
                    $files[] = $file;
                }
            }
        }

        return $files;
    }

    /**
     * @return array<string, mixed>
     */
    protected function leaves(mixed $value, string $prefix): array
    {
        if (! is_array($value)) {
            return [$prefix => $value];
        }

        $leaves = [];

        foreach ($value as $key => $child) {
            $leaves += $this->leaves($child, "{$prefix}.{$key}");
        }

        return $leaves;
    }
}