<?php

namespace App\Console\Commands;

use App\Console\Commands\Contracts\AttributeScanHandler;
use App\Console\Commands\Handlers\GenericSeoAttributeHandler;
use App\Console\Commands\Handlers\LayoutAttributeHandler;
use App\Console\Commands\Handlers\LayoutDataAttributeHandler;
use Illuminate\Console\Command;
use Illuminate\Support\Arr;
use Illuminate\Support\Facades\File;
use Illuminate\Support\Str;
use Symfony\Component\Finder\Finder;

/**
 * Scans the codebase for translation keys and compares them with the language files.
 *
 *  - default  : reports keys used in code but missing from the language files (--fix adds them)
 *  - --unused : reports keys defined in the language files but never used (--purge removes them)
 *
 * Keys are discovered from translation helper calls, PHP attributes / object instantiations
 * handled by registered AttributeScanHandlers, enum cases and permission definitions.
 */
class CheckMissingTranslations extends Command
{
    protected $signature = 'lang:check
                            {locale=en : The locale to check against}
                            {--skip=* : Additional paths, files, or globs to exclude}
                            {--ai : Output a structured prompt for AI to generate missing keys}
                            {--unused : Check for defined translation keys that are never used in codebase}
                            {--fix : Add missing keys to the language files using placeholder values}
                            {--purge : Remove unused keys from the language files (implies --unused)}
                            {--dry-run : Preview what --fix or --purge would change without writing anything}
                            {--force : Do not ask for confirmation before writing files}
                            {--mark= : Prefix for placeholder values created by --fix, for example TODO}
                            {--all-locales : With --purge or check, process every locale instead of only the given one}
                            {--include-json : With --purge, also remove unused JSON keys (risky, strings used by vendor packages are not detected)}';

    protected $description = 'Check for translation keys used in the application that are missing or defined keys that are unused';

    /** Bucket name used for the flat `{locale}.json` file inside the language data array. */
    private const JSON = '__json';

    /** Internal marker for the dynamic parts of a key, e.g. `'mail.' . $type` becomes `mail.<WILDCARD>`. */
    private const WILDCARD = "\x1A";

    /**
     * Recognised translation calls (the first argument is parsed separately):
     *  - __('x'), trans('x'), trans_choice('x')
     *  - @lang('x'), @choice('x')
     *  - Lang::get/choice/has/hasForLocale('x')
     *  - trans()->get('x'), app('translator')->get('x')
     */
    private const CALL_PATTERN = <<<'REGEX'
~
(?:
    (?<![\w$>])(?:trans\(\)|app\(\s*['"]translator['"]\s*\))\s*->\s*(?:get|choice|has)
  | (?<![\w$>:])(?:__|trans_choice|trans)
  | @(?:lang|choice)
  | (?<![\w$>])Lang::(?:get|choice|has|hasForLocale|getFromJson)
)
\s*\(\s*(?:key\s*:\s*)?
~x
REGEX;

    /** A single PHP string literal (single or double quoted, escapes supported, no line breaks). */
    private const LITERAL_PATTERN = '/(?|\'((?:[^\'\\\\\r\n]|\\\\.)*)\'|"((?:[^"\\\\\r\n]|\\\\.)*)")/';

    /** Shape of a dot-notation key: group[/sub].key[.nested] */
    private const KEY_SHAPE = '/^[A-Za-z0-9_\-]+(?:\/[A-Za-z0-9_\-]+)*(?:\.[A-Za-z0-9_\-]+)+$/';

    /** Directories (relative to base_path) that are scanned for key usage. */
    protected array $scanPaths = [
        'app',
        'routes',
        'resources/views',
    ];

    /** Anchored to base_path(), so `vendor` only excludes the root /vendor directory. */
    protected array $defaultExclusions = [
        'vendor',
        'storage',
        'bootstrap/cache',
        'node_modules',
        'resources/views/vendor',
        '.git',
    ];

    /** Keys generated for every `generatePolicy('model')` call: permissions.{model}.{suffix}. */
    protected array $permissionKeySuffixes = [
        'group-name',
        'viewAny',
        'view',
        'create',
        'update',
        'delete',
    ];

    /** Strings that look like keys but never are. */
    protected array $ignoredKeys = ['key'];

    /** Framework language files that are skipped by the unused check. */
    protected array $ignoredUnusedFiles = [
        'validation',
        'auth',
        'pagination',
        'passwords',
    ];

    protected int $scannedFiles = 0;

    /** @var array<string, array<string, array{file: string, line: int}>> Static keys found in code, with their locations. */
    protected array $foundKeys = [];

    /** @var array<string, array<string, array{file: string, line: int}>> Dynamic key patterns (glob style) found in code. */
    protected array $foundPatterns = [];

    /** @var array<string, AttributeScanHandler> Attribute / `new` handlers indexed by class name. */
    protected array $attributeHandlers = [];

    /** @var array<string, array> Language data cache indexed by locale. */
    private array $langCache = [];

    public function __construct()
    {
        parent::__construct();

        $this->registerAttributeHandler(new LayoutDataAttributeHandler());
        $this->registerAttributeHandler(new LayoutAttributeHandler());
        $this->registerAttributeHandler(new GenericSeoAttributeHandler('Seo'));
    }

    public function registerAttributeHandler(AttributeScanHandler $handler): void
    {
        $this->attributeHandlers[$handler->attributeClass()] = $handler;
    }

    // ------------------------------------------------------------------
    // Command flow
    // ------------------------------------------------------------------

    public function handle(): int
    {
        $purge = (bool) $this->option('purge');

        if ($purge && $this->option('fix')) {
            $this->error('--fix and --purge cannot be combined. Run them separately.');

            return Command::FAILURE;
        }

        if ($this->option('include-json') && ! $purge) {
            $this->error('--include-json can only be used together with --purge.');

            return Command::FAILURE;
        }

        $primaryLocale = $this->argument('locale');
        $locales = $this->option('all-locales') ? $this->discoverLocales() : [$primaryLocale];

        $this->info('Checking translation keys against locale(s): [' . implode(', ', $locales) . ']...');

        $this->scanCodebase();

        $this->line("Scanned {$this->scannedFiles} file(s), found " . count($this->foundKeys) . ' static key(s) and ' . count($this->foundPatterns) . ' dynamic pattern(s).');
        $this->newLine();

        return ($this->option('unused') || $purge)
            ? $this->checkUnusedKeys($primaryLocale)
            : $this->checkMissingKeys($primaryLocale, $locales);
    }

    /**
     * Reports (and optionally fixes) keys used in code that are missing from the given locales.
     */
    private function checkMissingKeys(string $primaryLocale, array $locales): int
    {
        $missingByLocale = [];

        foreach ($locales as $locale) {
            $langData = $this->langData($locale);

            $missing = array_filter(
                $this->foundKeys,
                fn (array $occurrences, string $key) => ! $this->hasKey($langData, $key),
                ARRAY_FILTER_USE_BOTH
            );

            if (! empty($missing)) {
                $missingByLocale[$locale] = $missing;
            }
        }

        if (empty($missingByLocale)) {
            $this->info('All translation keys are properly indexed across all checked locale(s)!');

            return Command::SUCCESS;
        }

        foreach ($missingByLocale as $locale => $missing) {
            $this->printMissingTable($locale, $missing);
        }

        if ($this->option('fix')) {
            $status = Command::SUCCESS;

            foreach ($missingByLocale as $locale => $missing) {
                if ($this->fixMissingKeys($locale, $missing) !== Command::SUCCESS) {
                    $status = Command::FAILURE;
                }
            }

            return $status;
        }

        if ($this->option('ai')) {
            $this->outputAiPrompt($primaryLocale, reset($missingByLocale));
        } else {
            $this->comment('Tip: Run with --ai to generate a copyable prompt for AI to fix these keys:');
            $this->line("  php artisan lang:check {$primaryLocale} --all-locales --ai");
            $this->comment('Or add placeholders to the language files (preview first with --dry-run):');
            $this->line("  php artisan lang:check {$primaryLocale} --all-locales --fix --dry-run");
        }

        return Command::FAILURE;
    }

    private function printMissingTable(string $locale, array $missing): void
    {
        $this->error('Found ' . count($missing) . " missing translation key(s) in locale [{$locale}]:");
        $this->newLine();

        $rows = [];
        foreach ($missing as $key => $occurrences) {
            foreach ($occurrences as $occurrence) {
                $rows[] = [$key, "{$occurrence['file']}:{$occurrence['line']}"];
            }
        }

        $this->table(['Missing Key', 'Used In'], $rows);
        $this->newLine();
    }

    /**
     * Reports (and optionally purges) keys that are defined but never used.
     */
    private function checkUnusedKeys(string $locale): int
    {
        $unusedKeys = $this->findUnusedKeys($this->langData($locale));

        if (empty($unusedKeys)) {
            $this->info('No unused translation keys found! All defined keys are actively used.');

            return Command::SUCCESS;
        }

        $this->warn('Found ' . count($unusedKeys) . ' unused translation key(s) in language files:');
        $this->newLine();

        $this->table(['Unused Defined Key'], array_map(fn (string $key) => [$key], $unusedKeys));

        if ($this->option('purge')) {
            return $this->purgeUnusedKeys($locale);
        }

        $this->newLine();
        $this->comment('Tip: remove them from the language files (preview first with --dry-run):');
        $this->line("  php artisan lang:check {$locale} --purge --dry-run");

        return Command::FAILURE;
    }

    // ------------------------------------------------------------------
    // Unused key detection
    // ------------------------------------------------------------------

    /**
     * @return array<int, string> Defined keys that nothing in the codebase uses.
     */
    private function findUnusedKeys(array $langData): array
    {
        $used = [];
        foreach (array_keys($this->foundKeys) as $key) {
            $used[$this->normalizeKey($key)] = true;
        }

        $patterns = array_unique(array_map(
            fn (string $pattern) => $this->normalizeKey($pattern),
            array_keys($this->foundPatterns)
        ));

        return array_values(array_filter(
            $this->flattenLangData($langData),
            fn (string $key) => ! $this->isIgnoredUnusedKey($key)
                && ! $this->isKeyCovered($this->normalizeKey($key), $used, $patterns)
        ));
    }

    /**
     * A defined key counts as used when it is referenced directly, when one of its parents is
     * referenced (e.g. __('group.parent') returns the whole array), or when it matches a dynamic pattern.
     */
    private function isKeyCovered(string $key, array $used, array $patterns): bool
    {
        if (isset($used[$key])) {
            return true;
        }

        $segments = explode('.', $key);
        for ($length = count($segments) - 1; $length > 0; $length--) {
            if (isset($used[implode('.', array_slice($segments, 0, $length))])) {
                return true;
            }
        }

        foreach ($patterns as $pattern) {
            if (Str::is($pattern, $key)) {
                return true;
            }
        }

        return false;
    }

    /**
     * Folder separators and dots are interchangeable when matching keys (`domains/x.key` equals `domains.x.key`).
     */
    private function normalizeKey(string $key): string
    {
        return str_replace('/', '.', $key);
    }

    private function isIgnoredUnusedKey(string $key): bool
    {
        foreach ($this->ignoredUnusedFiles as $ignored) {
            if (
                str_starts_with($key, "{$ignored}.")
                || str_contains($key, "/{$ignored}.")
                || str_contains($key, ".{$ignored}.")
            ) {
                return true;
            }
        }

        return false;
    }

    /**
     * @return array<int, string> Every defined key in dot notation (`group.nested.key` or the raw JSON key).
     */
    private function flattenLangData(array $langData): array
    {
        $flattened = [];

        foreach ($langData as $prefix => $data) {
            if ($prefix === self::JSON) {
                array_push($flattened, ...array_map('strval', array_keys($data)));
            } else {
                array_push($flattened, ...$this->flattenArray($data, (string) $prefix));
            }
        }

        return $flattened;
    }

    /**
     * Flattens an array into dot-notation keys. A list (0..n indexes) is kept as ONE key,
     * because it is consumed as a whole by __('group.key'), which returns the array.
     *
     * @return array<int, string>
     */
    private function flattenArray(array $data, string $prefix): array
    {
        $keys = [];

        foreach ($data as $key => $value) {
            $path = "{$prefix}.{$key}";

            if (is_array($value) && $value !== [] && ! $this->isList($value)) {
                array_push($keys, ...$this->flattenArray($value, $path));
            } else {
                $keys[] = $path;
            }
        }

        return $keys;
    }

    private function isList(array $array): bool
    {
        return array_keys($array) === array_keys(array_values($array));
    }

    // ------------------------------------------------------------------
    // Codebase scanning
    // ------------------------------------------------------------------

    private function scanCodebase(): void
    {
        $this->foundKeys = [];
        $this->foundPatterns = [];
        $this->scannedFiles = 0;

        $skips = array_filter((array) ($this->option('skip') ?? []));
        $selfPath = $this->slashes(__FILE__);

        foreach ($this->scanPaths as $path) {
            if (! File::isDirectory(base_path($path))) {
                continue;
            }

            foreach (Finder::create()->files()->in(base_path($path))->name('*.php') as $file) {
                $relativePath = $this->relativePath($file->getPathname());

                if ($this->slashes($file->getPathname()) === $selfPath || $this->isExcluded($relativePath, $skips)) {
                    continue;
                }

                $this->scannedFiles++;
                $this->scanFile($file->getContents(), $relativePath);
            }
        }
    }

    /**
     * Default exclusions are anchored to the project root, while --skip values match at any depth.
     */
    private function isExcluded(string $relativePath, array $skips): bool
    {
        foreach ($this->defaultExclusions as $excluded) {
            $excluded = trim($this->slashes($excluded), '/');

            if ($relativePath === $excluded || str_starts_with($relativePath, $excluded . '/')) {
                return true;
            }
        }

        foreach ($skips as $skip) {
            $skip = trim($this->slashes((string) $skip), '/');

            if ($skip === '') {
                continue;
            }

            if (str_contains($skip, '*')) {
                if (Str::is($skip, $relativePath) || Str::is('*/' . $skip, $relativePath)) {
                    return true;
                }

                continue;
            }

            if (
                $relativePath === $skip
                || str_starts_with($relativePath, $skip . '/')
                || str_contains($relativePath, '/' . $skip . '/')
                || str_ends_with($relativePath, '/' . $skip)
            ) {
                return true;
            }
        }

        return false;
    }

    private function scanFile(string $content, string $file): void
    {
        $content = $this->stripComments($content);

        $this->scanTranslationCalls($content, $file);
        $this->scanAttributeHandlers($content, $file);

        if (str_contains($content, 'InteractsWithLabels') && str_contains($content, 'enum ')) {
            $this->scanEnumKeys($content, $file);
        }

        if (str_contains($content, 'function permissions(')) {
            $this->scanPermissionKeys($content, $file);
        }
    }

    /**
     * Stores a discovered key (or a dynamic pattern) together with its location.
     */
    private function record(string $key, string $file, int $line, bool $dynamic = false): void
    {
        if (! $dynamic && $this->isInvalidKey($key)) {
            return;
        }

        $store = $dynamic ? 'foundPatterns' : 'foundKeys';
        $this->{$store}[$key]["{$file}:{$line}"] = ['file' => $file, 'line' => $line];
    }

    /**
     * Finds keys in translation helper calls such as __('x'), trans('x') or @lang('x').
     */
    private function scanTranslationCalls(string $content, string $file): void
    {
        if (! preg_match_all(self::CALL_PATTERN, $content, $matches, PREG_OFFSET_CAPTURE)) {
            return;
        }

        foreach ($matches[0] as [$text, $offset]) {
            $line = $this->lineAt($content, $offset);

            foreach ($this->parseFirstArgument($content, $offset + strlen($text)) as $result) {
                $this->record($result['key'], $file, $line, $result['dynamic']);
            }
        }
    }

    /**
     * Finds keys in `#[Name(...)]` attributes and `new Name(...)` instantiations by delegating
     * the interpretation of the arguments to the registered handler of that class.
     */
    private function scanAttributeHandlers(string $content, string $file): void
    {
        if (empty($this->attributeHandlers)) {
            return;
        }

        $names = implode('|', array_map('preg_quote', array_keys($this->attributeHandlers)));

        $patterns = [
            // #[Name(...)] attributes
            '/#\[(' . $names . ')\s*\(((?:[^)]|\n)*?)\)\]/',
            // new Name(...) / new \Fully\Qualified\Name(...), including multi-line bodies
            '/new\s+\\\\?(?:[A-Za-z0-9_]+\\\\)*(' . $names . ')\s*\(((?:[^)]|\n)*?)\)/s',
        ];

        foreach ($patterns as $pattern) {
            if (! preg_match_all($pattern, $content, $blocks, PREG_SET_ORDER | PREG_OFFSET_CAPTURE)) {
                continue;
            }

            foreach ($blocks as $block) {
                $handler = $this->attributeHandlers[$block[1][0]] ?? null;

                if ($handler === null) {
                    continue;
                }

                $line = $this->lineAt($content, $block[0][1]);
                $arguments = $this->parseAttributeArguments($block[2][0]);

                foreach ($handler->extractTranslationKeys($arguments) as $key) {
                    $this->record($key, $file, $line);
                }
            }
        }
    }

    /**
     * Turns the raw argument list of an attribute into an array for the handlers.
     * Variables and function calls are replaced by placeholders and named arguments become array keys.
     *
     * NOTE: this relies on eval(), so it must only ever run on trusted source code.
     */
    private function parseAttributeArguments(string $body): array
    {
        try {
            $clean = preg_replace('/(?<!\\\\)\$[A-Za-z_]\w*(?:->\w+|\[[^\]]*\])*/', "'{variable}'", $body);
            $clean = preg_replace('/[A-Za-z_]\w*\([^)]*\)/', "'{call}'", $clean);
            $evaluable = preg_replace('/([a-zA-Z0-9_]+)\s*:/', "'$1' =>", $clean);

            return eval("return [{$evaluable}];") ?? [];
        } catch (\Throwable) {
            return [];
        }
    }

    /**
     * Parses the first argument of a translation call.
     *
     * Supports:
     *  - 'key' / "key" (including apostrophes and escapes, e.g. __("You're receiving this email"))
     *  - 'prefix.' . $var . '.suffix'  => dynamic pattern "prefix.*.suffix"
     *  - "prefix.{$var}.suffix"        => dynamic pattern "prefix.*.suffix"
     *  - $cond ? 'a.b' : 'a.c'         => both literals are recorded as static keys
     *  - __('key') . ':'               => not dynamic (the concatenation is outside the call)
     *
     * @return array<int, array{key: string, dynamic: bool}>
     */
    private function parseFirstArgument(string $content, int $pos): array
    {
        $length = strlen($content);
        $operands = [];
        $buffer = '';
        $depth = 0;

        // Split the argument on top-level `.` (string concatenation) until the call ends.
        for ($i = $pos; $i < $length; $i++) {
            $char = $content[$i];

            if ($char === "'" || $char === '"') {
                $end = $this->skipString($content, $i);
                $buffer .= substr($content, $i, $end - $i + 1);
                $i = $end;

                continue;
            }

            if ($char === '(' || $char === '[' || $char === '{') {
                $depth++;
            } elseif ($char === ')' || $char === ']' || $char === '}') {
                if ($depth === 0) {
                    break;
                }
                $depth--;
            } elseif ($depth === 0 && $char === ',') {
                break;
            } elseif ($depth === 0 && $char === '.') {
                $prev = $content[$i - 1] ?? '';
                $next = $content[$i + 1] ?? '';
                $isSpread = $prev === '.' || $next === '.';
                $isDecimal = ctype_digit($prev) && ctype_digit($next);

                if (! $isSpread && ! $isDecimal) {
                    $operands[] = trim($buffer);
                    $buffer = '';

                    continue;
                }
            }

            $buffer .= $char;
        }

        $operands[] = trim($buffer);

        if ($operands[0] === '') {
            return []; // trans() / __() without arguments
        }

        $key = implode('', array_map(fn (string $operand) => $this->decodeOperand($operand), $operands));
        $key = preg_replace('/' . self::WILDCARD . '+/', self::WILDCARD, $key);

        // Fully dynamic, e.g. __($key): only pick up key-shaped literals (ternary / match branches).
        if ($key === self::WILDCARD) {
            $expression = implode(' ', $operands);
            // Strip helper calls whose arguments are never translation keys.
            $expression = preg_replace('/(?:config|route|env|view|session|old)\s*\((?:[^()]+|\([^()]*\))*\)/i', '', $expression);

            $results = [];
            foreach ($this->extractLiterals($expression) as [$literal]) {
                if (preg_match(self::KEY_SHAPE, $literal) && ! $this->isInvalidKey($literal)) {
                    $results[] = ['key' => $literal, 'dynamic' => false];
                }
            }

            return $results;
        }

        $dynamic = str_contains($key, self::WILDCARD);

        return [['key' => $dynamic ? str_replace(self::WILDCARD, '*', $key) : $key, 'dynamic' => $dynamic]];
    }

    /**
     * Returns the literal value of an operand, with the WILDCARD marker for anything dynamic.
     */
    private function decodeOperand(string $operand): string
    {
        if (preg_match('/^\'((?:[^\'\\\\]|\\\\.)*)\'$/s', $operand, $m)) {
            return str_replace(["\\'", '\\\\'], ["'", '\\'], $m[1]);
        }

        if (preg_match('/^"((?:[^"\\\\]|\\\\.)*)"$/s', $operand, $m)) {
            $inner = preg_replace(
                '/\{\$(?:[^{}]|\{[^{}]*\})*\}|(?<!\\\\)\$[A-Za-z_]\w*(?:->\w+|\[[^\]]*\])*/',
                self::WILDCARD,
                $m[1]
            );

            return stripcslashes($inner);
        }

        return self::WILDCARD;
    }

    /**
     * Index of the closing quote of the string literal that starts at $i (or the last index if unterminated).
     */
    private function skipString(string $text, int $i): int
    {
        $quote = $text[$i];
        $length = strlen($text);

        for ($i++; $i < $length && $text[$i] !== $quote; $i++) {
            if ($text[$i] === '\\') {
                $i++;
            }
        }

        return min($i, $length - 1);
    }

    /**
     * @return array<int, array{0: string, 1: int}> Every string literal as [content, offset].
     */
    private function extractLiterals(string $content): array
    {
        return preg_match_all(self::LITERAL_PATTERN, $content, $matches, PREG_OFFSET_CAPTURE) ? $matches[1] : [];
    }

    /**
     * Removes Blade comments, block comments that start a line and whole-line `//` comments.
     * Line breaks are preserved so reported line numbers stay accurate.
     */
    private function stripComments(string $content): string
    {
        $blank = static fn (array $m): string => str_repeat("\n", substr_count($m[0], "\n"));

        $content = preg_replace_callback('/\{\{--.*?--\}\}/s', $blank, $content) ?? $content;
        $content = preg_replace_callback('~^[ \t]*/\*.*?\*/~ms', $blank, $content) ?? $content;

        return preg_replace('~^[ \t]*//.*$~m', '', $content) ?? $content;
    }

    private function lineAt(string $content, int $offset): int
    {
        return substr_count($content, "\n", 0, $offset) + 1;
    }

    /**
     * Runs a pattern against every line.
     *
     * @return array<int, array{0: array, 1: int}> [regex matches, 1-based line number] for each matching line.
     */
    private function matchLines(string $content, string $pattern): array
    {
        $results = [];

        foreach (explode("\n", $content) as $index => $line) {
            if (preg_match($pattern, $line, $matches)) {
                $results[] = [$matches, $index + 1];
            }
        }

        return $results;
    }

    /**
     * Keys declared by `'description' => '...'` entries and by `generatePolicy('model')` calls.
     */
    private function scanPermissionKeys(string $content, string $file): void
    {
        foreach ($this->matchLines($content, '/[\'"]description[\'"]\s*=>\s*[\'"]([^\'"]+)[\'"]/') as [$match, $line]) {
            $this->record($match[1], $file, $line);
        }

        if (! preg_match_all('/generatePolicy\(\s*[\'"]([^\'"]+)[\'"]/', $content, $matches, PREG_OFFSET_CAPTURE)) {
            return;
        }

        foreach ($matches[1] as [$model, $offset]) {
            $line = $this->lineAt($content, $offset);

            foreach ($this->permissionKeySuffixes as $suffix) {
                $this->record("permissions.{$model}.{$suffix}", $file, $line);
            }

            // Wildcard so every permissions.{model}.* key counts as used by the unused check.
            $this->record("permissions.{$model}.*", $file, $line, true);
        }
    }

    /**
     * Keys derived from the cases of a backed enum that uses the InteractsWithLabels trait.
     * The prefix follows the enum namespace: domains/{domain}/enum.{slug}, ui/enum.{slug} or enum.{slug}.
     */
    private function scanEnumKeys(string $content, string $file): void
    {
        if (
            ! preg_match('/namespace\s+([^;]+);/', $content, $namespace)
            || ! preg_match('/enum\s+([^\s:]+)/', $content, $enum)
        ) {
            return;
        }

        $fqcn = trim($namespace[1]) . '\\' . trim($enum[1]);
        $slug = Str::snake(trim($enum[1]));

        if (Str::startsWith($fqcn, 'App\\Domains\\')) {
            $prefix = 'domains/' . Str::kebab(Str::between($fqcn, 'App\\Domains\\', '\\Enums\\')) . "/enum.{$slug}";
        } elseif (Str::startsWith($fqcn, 'App\\UI\\Enums\\')) {
            $prefix = "ui/enum.{$slug}";
        } else {
            $prefix = "enum.{$slug}";
        }

        foreach ($this->matchLines($content, '/case\s+[A-Za-z0-9_]+\s*=\s*[\'"]([^\'"]+)[\'"]\s*;/') as [$match, $line]) {
            $this->record("{$prefix}.{$match[1]}", $file, $line);
        }
    }

    /**
     * Strings that can never be translation keys: placeholders, variables, spread / namespace artefacts.
     */
    private function isInvalidKey(string $key): bool
    {
        return $key === ''
            || str_contains($key, '::')
            || str_contains($key, '{$')
            || preg_match('/^\$\w+$/', $key) === 1
            || preg_match('/\{[A-Za-z0-9_\.]+\}/', $key) === 1
            || preg_match('/^\{[A-Za-z0-9_]+\}$/', $key) === 1
            || str_contains($key, '...')
            || str_contains($key, ')]')
            || in_array($key, $this->ignoredKeys, true);
    }

    // ------------------------------------------------------------------
    // Language data
    // ------------------------------------------------------------------

    /**
     * Cached language data of a locale (see loadLanguageData()).
     */
    private function langData(string $locale): array
    {
        return $this->langCache[$locale] ??= $this->loadLanguageData($locale);
    }

    /**
     * Loads `lang/{locale}.json` into the JSON bucket and every `lang/{locale}/**.php` file
     * into a bucket named after its relative path without extension (e.g. `domains/billing/enum`).
     */
    private function loadLanguageData(string $locale): array
    {
        $langData = [];
        $jsonPath = lang_path("{$locale}.json");

        if (File::exists($jsonPath)) {
            $langData[self::JSON] = json_decode(File::get($jsonPath), true) ?? [];
        }

        if (File::isDirectory(lang_path($locale))) {
            foreach (File::allFiles(lang_path($locale)) as $file) {
                if ($file->getExtension() !== 'php') {
                    continue;
                }

                $content = require $file->getPathname();

                if (is_array($content)) {
                    $langData[substr($this->slashes($file->getRelativePathname()), 0, -4)] = $content;
                }
            }
        }

        return $langData;
    }

    /**
     * Whether a key is defined: either a flat JSON key or `bucket.nested.key` inside a PHP file.
     * Buckets are matched both literally and with `/` treated as `.`.
     */
    private function hasKey(array $langData, string $key): bool
    {
        if (isset($langData[self::JSON]) && array_key_exists($key, $langData[self::JSON])) {
            return true;
        }

        if (! str_contains($key, '.')) {
            return false;
        }

        foreach ($langData as $prefix => $data) {
            if ($prefix === self::JSON) {
                continue;
            }

            foreach ([[(string) $prefix, $key], [$this->normalizeKey((string) $prefix), $this->normalizeKey($key)]] as [$bucket, $candidate]) {
                if (str_starts_with($candidate, $bucket . '.') && Arr::has($data, substr($candidate, strlen($bucket) + 1))) {
                    return true;
                }
            }
        }

        return false;
    }

    /**
     * @return array<int, string> Every locale that has a directory or a JSON file in the lang path.
     */
    private function discoverLocales(): array
    {
        $locales = [];

        foreach (File::directories(lang_path()) as $dir) {
            if (basename($dir) !== 'vendor') {
                $locales[] = basename($dir);
            }
        }

        foreach (File::glob(lang_path('*.json')) ?: [] as $jsonFile) {
            $locales[] = basename($jsonFile, '.json');
        }

        return array_values(array_unique($locales));
    }

    // ------------------------------------------------------------------
    // Fix (add missing keys)
    // ------------------------------------------------------------------

    /**
     * Adds placeholder values for the missing keys of one locale.
     */
    private function fixMissingKeys(string $locale, array $missingKeys): int
    {
        ksort($missingKeys);

        $mark = (string) ($this->option('mark') ?? '');
        $mark = $mark === '' ? '' : rtrim($mark) . ' ';

        $data = $this->langData($locale);
        $added = [];
        $conflicts = [];

        foreach (array_keys($missingKeys) as $key) {
            [$bucket, $item] = $this->resolveTarget($key);
            $value = $mark . ($bucket === self::JSON ? $key : $this->humanize($item));

            if ($bucket === self::JSON) {
                $data[self::JSON][$key] = $value;
            } else {
                $data[$bucket] ??= [];

                if (! $this->setPath($data[$bucket], $item, $value)) {
                    $conflicts[] = $key;

                    continue;
                }
            }

            $added[$key] = ['bucket' => $bucket, 'value' => $value];
        }

        [$writable, $skipped] = $this->splitRewritable($locale, array_unique(array_column($added, 'bucket')));

        $rows = [];
        foreach ($added as $key => $info) {
            if (in_array($info['bucket'], $writable, true)) {
                $rows[] = [$key, $info['value'], $this->langFileLabel($locale, $info['bucket'])];
            }
        }

        $this->newLine();

        if (! empty($rows)) {
            $this->info('The following keys will be added:');
            $this->table(['Key', 'Placeholder Value', 'File'], $rows);
        }

        foreach ($conflicts as $key) {
            $this->error("Cannot add [{$key}]: a parent segment already holds a plain string value. Resolve it manually.");
        }

        $this->warnSkipped($skipped);

        $question = 'Write ' . count($rows) . ' key(s) into ' . count($writable) . ' file(s)? Comments and custom formatting in those files will be lost.';

        if (empty($writable) || ! $this->shouldWrite($question)) {
            return Command::FAILURE;
        }

        $this->writeBuckets($locale, $data, $writable);

        $this->info('Added ' . count($rows) . ' placeholder key(s) to ' . count($writable) . ' file(s). Replace the placeholder values with real translations.');

        return (empty($conflicts) && empty($skipped)) ? Command::SUCCESS : Command::FAILURE;
    }

    /**
     * Dot-notation keys (`group.item`) go to the PHP file of their group, anything else
     * (sentences, spaces, trailing dots, ...) goes to the JSON file.
     *
     * @return array{0: string, 1: string} [bucket, item]
     */
    private function resolveTarget(string $key): array
    {
        return preg_match(self::KEY_SHAPE, $key) ? explode('.', $key, 2) : [self::JSON, $key];
    }

    /**
     * Turns the last key segment into a readable placeholder, e.g. `viewAny` becomes "View any".
     */
    private function humanize(string $item): string
    {
        $segments = explode('.', $item);
        $words = preg_replace('/(?<=[a-z0-9])(?=[A-Z])/', ' ', (string) end($segments));

        return ucfirst(mb_strtolower(trim(str_replace(['-', '_'], ' ', $words))));
    }

    /**
     * Sets a dot-notation path. Returns false when the target exists or a parent holds a
     * non-array value, because writing would overwrite existing data.
     */
    private function setPath(array &$data, string $path, string $value): bool
    {
        $segments = explode('.', $path);
        $last = count($segments) - 1;
        $ref = &$data;

        foreach ($segments as $index => $segment) {
            if ($index === $last) {
                if (array_key_exists($segment, $ref)) {
                    return false;
                }

                $ref[$segment] = $value;

                return true;
            }

            $ref[$segment] ??= [];

            if (! is_array($ref[$segment])) {
                return false;
            }

            $ref = &$ref[$segment];
        }

        return false;
    }

    // ------------------------------------------------------------------
    // Purge (remove unused keys)
    // ------------------------------------------------------------------

    /**
     * Removes the unused keys of the given locale (or of every locale with --all-locales).
     * Unused keys are recalculated per locale because each one may define different keys.
     */
    private function purgeUnusedKeys(string $primaryLocale): int
    {
        $includeJson = (bool) $this->option('include-json');
        $locales = $this->option('all-locales') ? $this->discoverLocales() : [$primaryLocale];

        $plans = [];
        $skippedJson = 0;
        $skippedFiles = [];

        foreach ($locales as $locale) {
            $data = $this->langData($locale);
            $removed = [];

            foreach ($this->findUnusedKeys($data) as $key) {
                $bucket = $this->locateKey($data, $key);

                if ($bucket === null) {
                    continue;
                }

                if ($bucket === self::JSON) {
                    if (! $includeJson) {
                        $skippedJson++;

                        continue;
                    }

                    unset($data[self::JSON][$key]);
                } else {
                    $this->forgetPath($data[$bucket], substr($key, strlen($bucket) + 1));
                }

                $removed[$bucket][] = $key;
            }

            [$writable, $skipped] = $this->splitRewritable($locale, array_keys($removed));
            array_push($skippedFiles, ...$skipped);

            if (! empty($writable)) {
                $plans[$locale] = ['data' => $data, 'removed' => array_intersect_key($removed, array_flip($writable))];
            }
        }

        $this->newLine();
        $this->warnSkipped($skippedFiles);

        if ($skippedJson > 0) {
            $this->comment("{$skippedJson} unused JSON key(s) were left untouched. Use --include-json to remove them as well.");
        }

        if (empty($plans)) {
            $this->warn('Nothing can be purged automatically.');

            return Command::FAILURE;
        }

        $rows = [];
        $total = 0;
        foreach ($plans as $locale => $plan) {
            foreach ($plan['removed'] as $bucket => $keys) {
                $rows[] = [$locale, $this->langFileLabel($locale, $bucket), count($keys)];
                $total += count($keys);
            }
        }

        $this->info('The following keys will be removed:');
        $this->table(['Locale', 'File', 'Keys to Remove'], $rows);

        if (! $this->shouldWrite("Remove {$total} key(s) from " . count($rows) . ' file(s)? Comments and custom formatting in those files will be lost.')) {
            return Command::FAILURE;
        }

        foreach ($plans as $locale => $plan) {
            $this->writeBuckets($locale, $plan['data'], array_keys($plan['removed']));
        }

        $this->info("Removed {$total} unused key(s) from " . count($rows) . ' file(s).');

        return empty($skippedFiles) ? Command::SUCCESS : Command::FAILURE;
    }

    /**
     * Finds the bucket (JSON or PHP file) that defines a flattened key.
     */
    private function locateKey(array $data, string $key): ?string
    {
        if (isset($data[self::JSON]) && array_key_exists($key, $data[self::JSON])) {
            return self::JSON;
        }

        foreach (array_keys($data) as $bucket) {
            if ($bucket !== self::JSON && str_starts_with($key, $bucket . '.')) {
                return $bucket;
            }
        }

        return null;
    }

    /**
     * Removes a dot-notation path and prunes parent arrays that become empty.
     */
    private function forgetPath(array &$data, string $path): void
    {
        if (array_key_exists($path, $data)) {
            unset($data[$path]);

            return;
        }

        if (! str_contains($path, '.')) {
            return;
        }

        [$head, $tail] = explode('.', $path, 2);

        if (! is_array($data[$head] ?? null)) {
            return;
        }

        $this->forgetPath($data[$head], $tail);

        if ($data[$head] === []) {
            unset($data[$head]);
        }
    }

    // ------------------------------------------------------------------
    // Writing language files (shared by --fix and --purge)
    // ------------------------------------------------------------------

    /**
     * Splits buckets into files that can be rewritten and PHP files that must be left alone.
     *
     * @return array{0: array<int, string>, 1: array<int, string>} [writable buckets, skipped file paths]
     */
    private function splitRewritable(string $locale, array $buckets): array
    {
        $writable = [];
        $skipped = [];

        foreach ($buckets as $bucket) {
            $path = lang_path("{$locale}/{$bucket}.php");

            if ($bucket !== self::JSON && ! $this->isSafelyRewritable($path)) {
                $skipped[] = $path;
            } else {
                $writable[] = $bucket;
            }
        }

        return [$writable, $skipped];
    }

    private function warnSkipped(array $paths): void
    {
        foreach ($paths as $path) {
            $this->warn('Skipped ' . $this->relativePath($path) . ': it contains executable PHP (closures, constants, function calls) and cannot be rewritten safely. Edit it manually.');
        }
    }

    /**
     * Applies --dry-run / --force / interactive confirmation. Returns true when files may be written.
     */
    private function shouldWrite(string $question): bool
    {
        if ($this->option('dry-run')) {
            $this->comment('Dry run: no files were written.');

            return false;
        }

        if (! $this->option('force') && ! $this->confirm($question, false)) {
            $this->comment('Aborted. No files were written.');

            return false;
        }

        return true;
    }

    private function writeBuckets(string $locale, array $data, array $buckets): void
    {
        foreach ($buckets as $bucket) {
            $this->writeLangFile($locale, $bucket, $data[$bucket] ?? []);
        }
    }

    private function writeLangFile(string $locale, string $bucket, array $data): void
    {
        if ($bucket === self::JSON) {
            $json = json_encode(
                $data === [] ? new \stdClass : $data,
                JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES | JSON_FORCE_OBJECT
            );

            File::put(lang_path("{$locale}.json"), $json . "\n");

            return;
        }

        $path = lang_path("{$locale}/{$bucket}.php");
        File::ensureDirectoryExists(dirname($path));
        File::put($path, "<?php\n\nreturn " . $this->exportPhpArray($data) . ";\n");
    }

    /**
     * Exports an array as short-syntax PHP with 4-space indentation.
     */
    private function exportPhpArray(array $data, int $depth = 0): string
    {
        if ($data === []) {
            return '[]';
        }

        $indent = str_repeat('    ', $depth + 1);
        $isList = $this->isList($data);
        $lines = [];

        foreach ($data as $key => $value) {
            $keyPart = $isList ? '' : $this->exportScalar($key) . ' => ';
            $valuePart = is_array($value) ? $this->exportPhpArray($value, $depth + 1) : $this->exportScalar($value);

            $lines[] = $indent . $keyPart . $valuePart . ',';
        }

        return "[\n" . implode("\n", $lines) . "\n" . str_repeat('    ', $depth) . ']';
    }

    private function exportScalar(mixed $value): string
    {
        return match (true) {
            is_string($value) => "'" . str_replace(['\\', "'"], ['\\\\', "\\'"], $value) . "'",
            is_bool($value) => $value ? 'true' : 'false',
            $value === null => 'null',
            default => var_export($value, true),
        };
    }

    /**
     * A language file can only be re-exported safely when it contains pure literals
     * (arrays, strings, numbers, true/false/null). Closures, constants, concatenation or
     * function calls would be lost or changed by an export.
     */
    private function isSafelyRewritable(string $path): bool
    {
        if (! File::exists($path)) {
            return true;
        }

        $allowedTokens = [
            T_OPEN_TAG, T_WHITESPACE, T_COMMENT, T_DOC_COMMENT, T_RETURN, T_ARRAY,
            T_DOUBLE_ARROW, T_CONSTANT_ENCAPSED_STRING, T_LNUMBER, T_DNUMBER, T_DECLARE,
        ];

        foreach (token_get_all(File::get($path)) as $token) {
            if (is_string($token)) {
                if (! str_contains('[],();-+=', $token)) {
                    return false;
                }

                continue;
            }

            [$id, $text] = $token;

            if (in_array($id, $allowedTokens, true)) {
                continue;
            }

            if ($id === T_STRING && in_array(strtolower($text), ['true', 'false', 'null', 'strict_types'], true)) {
                continue;
            }

            return false;
        }

        return true;
    }

    // ------------------------------------------------------------------
    // Paths and output helpers
    // ------------------------------------------------------------------

    private function slashes(string $path): string
    {
        return str_replace('\\', '/', $path);
    }

    private function relativePath(string $path): string
    {
        return ltrim(str_replace(rtrim($this->slashes(base_path()), '/'), '', $this->slashes($path)), '/');
    }

    private function langFileLabel(string $locale, string $bucket): string
    {
        return $this->relativePath($bucket === self::JSON ? lang_path("{$locale}.json") : lang_path("{$locale}/{$bucket}.php"));
    }

    /**
     * Prints a ready-to-copy prompt that asks an AI assistant to write the missing translations.
     */
    private function outputAiPrompt(string $locale, array $missingKeys): void
    {
        $this->newLine();
        $this->info('==================== AI TRANSLATION PROMPT ====================');
        $this->comment('Copy the block below and paste it into ChatGPT, Claude, Gemini, or Cursor:');
        $this->newLine();

        // Group by the first key segment, which is also the language file the key belongs to.
        $groupedByDomain = [];
        foreach ($missingKeys as $key => $occurrences) {
            $parts = explode('.', $key);
            $domain = count($parts) > 1 ? array_shift($parts) : 'general';
            $groupedByDomain[$domain][$key] = array_column($occurrences, 'file');
        }

        $prompt = "I have missing translation keys in my Laravel project for locale [{$locale}].\n";
        $prompt .= "Please generate the corresponding PHP array files or JSON entries for these keys.\n\n";
        $prompt .= "### Expected Structure:\n";
        $prompt .= "- For domain-prefixed keys (e.g. `domains/identity.field.user.name`), create or update `lang/{$locale}/domains/identity.php`.\n";
        $prompt .= "- Keys without a dot (e.g. `You're receiving this email`) belong in `lang/{$locale}.json`.\n";
        $prompt .= "- Use proper nested PHP arrays representing dot-notation keys.\n";
        $prompt .= "- Translate values naturally for target locale [{$locale}].\n\n";
        $prompt .= "### Missing Keys to Index:\n\n";

        foreach ($groupedByDomain as $domain => $keys) {
            $prompt .= "#### Domain/File: {$domain}\n";

            foreach ($keys as $key => $files) {
                $prompt .= "- `{$key}` (Used in: " . implode(', ', array_slice(array_unique($files), 0, 2)) . ")\n";
            }

            $prompt .= "\n";
        }

        $prompt .= 'Please output the ready-to-use PHP array code for each file.';

        $this->line($prompt);
        $this->newLine();
        $this->info('===============================================================');
    }
}