<?php

readonly class stow
{
    public const ACTION_STOW = 'stow';
    public const ACTION_UNSTOW = 'unstow';

    public function __construct(
        private string $action = self::ACTION_STOW,
        private bool   $backup = false,
        private bool   $force = false,
    ) {}

    private function getNoStow(string $path): array
    {
        if (file_exists(path($path, '.nostow'))) {
            $noStow = file_get_contents(path($path, '.nostow'));
            if ($noStow === false) {
                return [];
            }
            return array_values(array_filter(array_map('trim', explode(PHP_EOL, $noStow))));
        } else {
            return [];
        }
    }

    function run(string $sourcePath, string $targetPath): void
    {
        $noStow = $this->getNoStow($sourcePath);
        $sourceFiles = array_diff(scandir($sourcePath), ['..', '.', '.nostow', ...$noStow]);

        foreach ($sourceFiles as $sourceFile) {
            $targetFile = path($targetPath, $sourceFile);
            $stowFile = path($sourcePath, $sourceFile);

            switch ($this->action) {
                case self::ACTION_STOW:
                    $this->stow($targetFile, $stowFile);
                    break;
                case self::ACTION_UNSTOW:
                    $this->unstow($targetFile, $stowFile);
                    break;
                default:
                    line("Unknown action: {$this->action}");
                    return;
            }
        }
    }

    public function stow(string $targetFile, string $stowFile): void
    {
        if (is_link($targetFile)) {
            $targetLink = readlink($targetFile);
            if ($targetLink === $stowFile) {
                line("File $targetFile is already stowed from $stowFile");
            } else {
                line("File $targetFile is linked from $targetLink");
            }
            return;
        }
        if (is_dir($targetFile)) {
            if (is_dir($stowFile)) {
                line("File $targetFile and $stowFile are folders, recurse into existing folders");
                $this->run($stowFile, $targetFile);
            } else {
                line("File $targetFile is a folder, but stow file $stowFile is not a folder");
            }
            return;
        }
        if (is_file($targetFile)) {
            if ($this->backup) {
                $backFile = $targetFile . '.bak';
                if (is_file($backFile)) {
                    line("Backup file $backFile already exists");
                    return;
                }
                rename($targetFile, $backFile);
                line("Backup file $targetFile to $backFile");
            } elseif ($this->force) {
                line("Todo: delete file $targetFile");
                return;
            } else {
                line("File $targetFile already exists");
                return;
            }
        }
        line("Stow $targetFile from $stowFile");
        symlink($stowFile, $targetFile);
    }

    public function unstow(string $targetFile, string $stowFile): void
    {
        if (is_link($targetFile) && readlink($targetFile) === $stowFile) {
            line("Unstow $targetFile from $stowFile");
            unlink($targetFile);
            return;
        }
        if (is_dir($targetFile)) {
            if (is_dir($stowFile)) {
                line("File $targetFile and $stowFile are folders, recurse into existing folders");
                $this->run($stowFile, $targetFile);
                return;
            } else {
                line("File $targetFile is a folder, but stow file $stowFile is not a folder");
            }
        }
        line("File $targetFile is not stowed from $stowFile");
    }
}