<?php

declare(strict_types=1);

namespace DTS;

use DTS\Todo;

class TodoRepository implements \Iterator
{
    private string $pathToRepository;

    private array $repository = [];

    private array $tags = [];

    private int $position = 0;

    function __construct(string $pathToRepository)
    {
        $this->pathToRepository = $pathToRepository;

        $this->load();
    }

    public function sort(bool $asc = true): TodoRepository
    {
        usort($this->repository, function ($a, $b) use ($asc) {
            return $asc ? $a->task <=> $b->task
                : $b->task <=> $a->task;
        });

        return $this;
    }

    public function filter(string $tag): TodoRepository
    {
        $this->repository = array_filter(
            $this->repository,
            fn($todo) => $todo->tag === $tag
        );

        return $this;
    }

    public function find(string $id): ?Todo
    {
        return $this->repository[$id] ?? null;
    }

    public function add(Todo $todo): bool
    {
        $this->repository[] = $todo;

        return $this->save();
    }

    public function update(Todo $todo): bool
    {
        if (array_key_exists($todo->id, $this->repository)) {
            $this->repository[$todo->id] = $todo;

            return $this->save();
        }

        return false;
    }

    public function delete(Todo $todo): bool
    {
        if (array_key_exists($todo->id, $this->repository)) {
            unset($this->repository[$todo->id]);

            return $this->save();
        }

        return false;
    }

    public function tags(): array
    {
        return $this->tags;
    }

    public function current()
    {
        return $this->repository[$this->position];
    }

    public function key()
    {
        return $this->position;
    }

    public function next(): void
    {
        ++$this->position;
    }

    public function rewind(): void
    {
        $this->position = 0;
    }

    public function valid(): bool
    {
        return isset($this->repository[$this->position]);
    }

    private function load(): void
    {
        if (!is_file($this->pathToRepository) || !is_readable($this->pathToRepository)) {
            throw new \Exception("Unable to locate repository {$this->pathToRepository}");
        }

        if (($fp = fopen($this->pathToRepository, 'r')) === FALSE) {
            throw new \Exception("Unable to read from repository {$this->pathToRepository}");
        }

        $id = 0;

        while (($data = fgetcsv($fp)) !== FALSE) {
            $todo = new Todo();

            $todo->id = $id++;
            $todo->task = $data[0];
            $todo->tag = $data[1];
            $todo->addedAt = $data[2];

            $this->repository[] = $todo;

            $this->tags[] = $todo->tag;
        }

        $this->tags = array_filter(array_unique($this->tags));

        sort($this->tags);

        fclose($fp);
    }

    private function save(): bool
    {
        if (($fp = fopen($this->pathToRepository, 'w')) === FALSE) {
            throw new \Exception("Unable to open repository {$this->pathToRepository}");
        }

        $success = true;

        foreach ($this->repository as $todo) {
            $success = $success && fputcsv($fp, [
                $todo->task,
                $todo->tag,
                $todo->addedAt,
            ]) !== false;
        }

        fclose($fp);

        return $success;
    }
}