<?php

declare(strict_types=1);

namespace Tests\Feature;

use Illuminate\Database\Migrations\Migration;
use Illuminate\Foundation\Testing\RefreshDatabase;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Schema;
use Tests\TestCase;

class CountBackfillMigrationTest extends TestCase
{
    use RefreshDatabase;

    private const MIGRATION = __DIR__.'/../../database/migrations/2026_08_15_000002_add_count_to_trackers_drop_entries.php';

    // Each require returns a fresh anonymous-class instance; there is no name to collide.
    private function migration(): Migration
    {
        return require self::MIGRATION;
    }

    /**
     * Rebuild the pre-migration shape: entries present, trackers without a count.
     */
    private function revertToLedger(): void
    {
        $this->migration()->down();
    }

    private function makeTracker(): int
    {
        return DB::table('trackers')->insertGetId([
            'label' => 'Counter',
            'unit' => 'units',
            'created_at' => now(),
            'updated_at' => now(),
        ]);
    }

    private function addEntry(int $trackerId, string $quantity): void
    {
        DB::table('entries')->insert([
            'tracker_id' => $trackerId,
            'date' => now()->toDateString(),
            'quantity' => $quantity,
            'created_at' => now(),
            'updated_at' => now(),
        ]);
    }

    private function countFor(int $trackerId): int
    {
        return (int) DB::table('trackers')->where('id', $trackerId)->value('count');
    }

    public function test_backfill_sums_entries_into_count(): void
    {
        $this->revertToLedger();

        $trackerId = $this->makeTracker();
        $this->addEntry($trackerId, '10');
        $this->addEntry($trackerId, '15');

        $this->migration()->up();

        $this->assertSame(25, $this->countFor($trackerId));
    }

    public function test_backfill_rounds_fractional_totals(): void
    {
        $this->revertToLedger();

        $trackerId = $this->makeTracker();
        $this->addEntry($trackerId, '1.4');
        $this->addEntry($trackerId, '1.2');

        $this->migration()->up();

        $this->assertSame(3, $this->countFor($trackerId));
    }

    public function test_backfill_clamps_negative_totals_to_zero(): void
    {
        $this->revertToLedger();

        $trackerId = $this->makeTracker();
        $this->addEntry($trackerId, '5');
        $this->addEntry($trackerId, '-9');

        $this->migration()->up();

        $this->assertSame(0, $this->countFor($trackerId));
    }

    public function test_tracker_without_entries_defaults_to_zero(): void
    {
        $this->revertToLedger();

        $trackerId = $this->makeTracker();

        $this->migration()->up();

        $this->assertSame(0, $this->countFor($trackerId));
    }

    public function test_up_drops_the_entries_table(): void
    {
        $this->revertToLedger();
        $this->assertTrue(Schema::hasTable('entries'));

        $this->migration()->up();

        $this->assertFalse(Schema::hasTable('entries'));
        $this->assertTrue(Schema::hasColumn('trackers', 'count'));
    }

    // The two down() tests start from the migrated schema, so they do not call revertToLedger().
    public function test_down_recreates_entries_from_count(): void
    {
        $trackerId = $this->makeTracker();
        DB::table('trackers')->where('id', $trackerId)->update(['count' => 7]);

        $this->migration()->down();

        $this->assertTrue(Schema::hasTable('entries'));
        $this->assertFalse(Schema::hasColumn('trackers', 'count'));

        $entries = DB::table('entries')->where('tracker_id', $trackerId)->get();

        $this->assertCount(1, $entries);
        $this->assertSame(7.0, (float) $entries->first()->quantity);
    }

    public function test_down_writes_no_entry_for_a_zero_count(): void
    {
        $trackerId = $this->makeTracker();

        $this->migration()->down();

        $this->assertSame(0, DB::table('entries')->where('tracker_id', $trackerId)->count());
    }
}