<?php

declare(strict_types=1);

namespace GitContributionGraph\Command;

use GitContributionGraph\Service\ContributionStore;
use GitContributionGraph\Service\Provider\ProviderInterface;
use Symfony\Component\Console\Attribute\AsCommand;
use Symfony\Component\Console\Attribute\Option;
use Symfony\Component\Console\Command\Command;
use Symfony\Component\Console\Helper\ProgressBar;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Output\OutputInterface;
use Symfony\Component\Console\Style\SymfonyStyle;
use Symfony\Component\DependencyInjection\Attribute\AutowireIterator;

#[AsCommand(
    name: 'graph:contributions:refetch',
    description: 'Force a full or ranged re-fetch of contribution history into the store.',
)]
final class RefetchContributionsCommand extends Command
{
    private const MAX_CHUNK_DAYS = 365;
    private const ALL_SINCE = '2005-01-01';

    private SymfonyStyle $io;

    /** @param iterable<ProviderInterface> $providers */
    public function __construct(
        #[AutowireIterator('app.provider')]
        private readonly iterable $providers,
        private readonly ContributionStore $store,
    ) {
        parent::__construct();
    }

    /** Symfony console lifecycle hook: sets up the styled I/O helper used throughout the command. */
    public function initialize(InputInterface $input, OutputInterface $output): void
    {
        $this->io = new SymfonyStyle($input, $output);
    }

    /**
     * Bypasses the aggregator's incremental trailing-window fetch to re-pull a full or explicit
     * date range for one, several, or all configured providers, chunked into ≤365-day windows.
     *
     * @param  string $provider comma-separated provider names to refetch; empty = all configured
     * @param  string $from     start date (YYYY-MM-DD); empty defaults to 365 days ago
     * @param  string $to       end date (YYYY-MM-DD); empty defaults to today
     * @param  bool   $all      shorthand for --from=2005-01-01
     * @return int    Command::SUCCESS if at least one provider refetched cleanly, else Command::FAILURE
     */
    public function __invoke(
        #[Option('Comma-separated provider names to refetch (default: all configured)', 'provider', 'p')]
        string $provider = '',
        #[Option('Start date (YYYY-MM-DD), default: 365 days ago', 'from')]
        string $from = '',
        #[Option('End date (YYYY-MM-DD), default: today', 'to')]
        string $to = '',
        #[Option('Refetch full history (from ' . self::ALL_SINCE . ')', 'all')]
        bool $all = false,
    ): int {
        $byName = $this->resolveProviders($provider);
        if ($byName === null) {
            return Command::FAILURE;
        }

        $fromSpec = match (true) {
            $all         => self::ALL_SINCE,
            $from !== '' => $from,
            default      => '-365 days',
        };

        $fromDate = new \DateTimeImmutable($fromSpec);
        $toDate   = new \DateTimeImmutable($to !== '' ? $to : 'today');
        $chunks   = $this->chunk($fromDate, $toDate);

        $summary   = [];
        $succeeded = 0;

        foreach ($byName as $name => $providerInstance) {
            [$daysWritten, $errors] = $this->refetchProvider($name, $providerInstance, $chunks);

            if ($errors === 0) {
                $succeeded++;
            }

            $summary[] = [$name, $daysWritten, count($chunks), $errors];
        }

        $this->io->table(['Provider', 'Days written', 'Chunks fetched', 'Errors'], $summary);

        if ($succeeded === 0) {
            $this->io->error('No provider completed successfully.');

            return Command::FAILURE;
        }

        $this->io->success(sprintf('%d of %d provider(s) refetched successfully.', $succeeded, count($byName)));

        return Command::SUCCESS;
    }

    /**
     * @param list<array{0: \DateTimeImmutable, 1: \DateTimeImmutable}> $chunks
     *
     * @return array{0: int, 1: int} days written, errors
     */
    private function refetchProvider(string $name, ProviderInterface $provider, array $chunks): array
    {
        $this->io->section("Refetching {$name}");

        $progress = new ProgressBar($this->io, count($chunks));
        $progress->start();

        $daysWritten = 0;
        $errors      = 0;

        foreach ($chunks as [$chunkFrom, $chunkTo]) {
            try {
                $fresh = $provider->resolveFetch($provider->startFetch($chunkFrom, $chunkTo));

                $dateCounts = [];
                foreach ($fresh as $date => $count) {
                    $dateCounts[(new \DateTimeImmutable($date))->getTimestamp()] = $count;
                }

                $this->store->merge($name, $dateCounts);
                $daysWritten += count($dateCounts);
            } catch (\Throwable $e) {
                $errors++;
                $this->io->warning("{$name}: {$e->getMessage()}");
            }

            $progress->advance();
        }

        $progress->finish();
        $this->io->newLine(2);

        return [$daysWritten, $errors];
    }

    /**
     * @return array<string, ProviderInterface>|null null when an unknown provider name was requested
     */
    private function resolveProviders(string $requested): ?array
    {
        $byName = [];
        foreach ($this->providers as $providerInstance) {
            $byName[$providerInstance->getName()] = $providerInstance;
        }

        if ($requested === '') {
            return array_filter($byName, static fn (ProviderInterface $p): bool => $p->isConfigured());
        }

        $names = explode(',', $requested);
        foreach ($names as $name) {
            if (!isset($byName[$name])) {
                $this->io->error("Unknown provider: {$name}");

                return null;
            }
        }

        return array_intersect_key($byName, array_flip($names));
    }

    /**
     * @return list<array{0: \DateTimeImmutable, 1: \DateTimeImmutable}>
     */
    private function chunk(\DateTimeImmutable $from, \DateTimeImmutable $to): array
    {
        $chunks = [];
        $cursor = $from;

        while ($cursor < $to) {
            $chunkEnd = min($cursor->modify('+' . (self::MAX_CHUNK_DAYS - 1) . ' days'), $to);
            $chunks[] = [$cursor, $chunkEnd];
            $cursor   = $chunkEnd->modify('+1 day');
        }

        if ($chunks === []) {
            $chunks[] = [$from, $to];
        }

        return $chunks;
    }
}