<?php

namespace App\Services;

use App\Models\Product;
use App\Models\Production;
use App\Models\ProductionIngredient;
use App\Models\StockEntry;
use Carbon\Carbon;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\DB;
use Illuminate\Validation\ValidationException;

class ProductionService
{
    public function __construct(
        protected ProductStockService $productStockService,
    ) {}

    /**
     * @param  array<string, mixed>  $data
     * @param  array<int, array{ingredient_id: int, stock_entry_id: int, quantity_used: float|int|string}>  $ingredientLines
     */
    public function store(array $data, array $ingredientLines, int $userId): Production
    {
        return DB::transaction(function () use ($data, $ingredientLines, $userId) {
            $product = Product::query()
                ->with(['manufacturer_ingredients', 'packagings'])
                ->findOrFail($data['product_id']);

            $locationId = (int) $data['location_id'];
            $producedQty = (int) $data['quantity'];
            if ($producedQty < 1) {
                throw ValidationException::withMessages(['quantity' => __('Die Stückzahl muss mindestens 1 sein.')]);
            }

            $this->assertNotASet($product);

            if ($product->no_recipe_required) {
                $ingredientLines = [];
            } else {
                $this->assertManufacturerRecipe($product);

                $requiredGrams = $this->requiredGramsByIngredient($product, $producedQty);

                $this->assertLinesMatchRecipe($requiredGrams, $ingredientLines);

                foreach ($ingredientLines as $line) {
                    $this->assertStockEntryMatchesLine($line, $locationId);
                }
            }

            $mhdWarning = $this->computeMhdWarning($product, $data['produced_at'], $ingredientLines);

            $production = Production::query()->create([
                'product_id' => $product->id,
                'location_id' => $locationId,
                'produced_by' => $userId,
                'produced_at' => $data['produced_at'],
                'quantity' => $producedQty,
                'notes' => $data['notes'] ?? null,
                'mhd_warning' => $mhdWarning,
            ]);

            foreach ($ingredientLines as $line) {
                $production->productionIngredients()->create([
                    'ingredient_id' => (int) $line['ingredient_id'],
                    'stock_entry_id' => (int) $line['stock_entry_id'],
                    'quantity_used' => $this->parseQuantity($line['quantity_used'] ?? null),
                ]);
            }

            $this->syncPackagingSnapshot($production, $product, $producedQty);

            $production->setRelation('product', $product);
            $this->productStockService->recordProductionStock($production, $userId);

            return $production->fresh(['product', 'location', 'productionIngredients', 'productionPackagings']);
        });
    }

    /**
     * @param  array<string, mixed>  $data
     * @param  array<int, array{ingredient_id: int, stock_entry_id: int, quantity_used: float|int|string}>  $ingredientLines
     */
    public function updateProduction(Production $production, array $data, array $ingredientLines, int $userId): Production
    {
        return DB::transaction(function () use ($production, $data, $ingredientLines, $userId) {
            $product = Product::query()
                ->with(['manufacturer_ingredients', 'packagings'])
                ->findOrFail($data['product_id']);

            $locationId = (int) $data['location_id'];
            $producedQty = (int) $data['quantity'];
            if ($producedQty < 1) {
                throw ValidationException::withMessages(['quantity' => __('Die Stückzahl muss mindestens 1 sein.')]);
            }

            $this->assertNotASet($product);

            if ($product->no_recipe_required) {
                $ingredientLines = [];
            } else {
                $this->assertManufacturerRecipe($product);

                $requiredGrams = $this->requiredGramsByIngredient($product, $producedQty);

                $this->assertLinesMatchRecipe($requiredGrams, $ingredientLines);

                foreach ($ingredientLines as $line) {
                    $this->assertStockEntryMatchesLine($line, $locationId);
                }
            }

            $mhdWarning = $this->computeMhdWarning($product, $data['produced_at'], $ingredientLines);

            $production->update([
                'product_id' => $product->id,
                'location_id' => $locationId,
                'produced_at' => $data['produced_at'],
                'quantity' => $producedQty,
                'notes' => $data['notes'] ?? null,
                'mhd_warning' => $mhdWarning,
            ]);

            $production->productionIngredients()->delete();
            foreach ($ingredientLines as $line) {
                $production->productionIngredients()->create([
                    'ingredient_id' => (int) $line['ingredient_id'],
                    'stock_entry_id' => (int) $line['stock_entry_id'],
                    'quantity_used' => $this->parseQuantity($line['quantity_used'] ?? null),
                ]);
            }

            $production->productionPackagings()->delete();
            $this->syncPackagingSnapshot($production, $product, $producedQty);

            $production->setRelation('product', $product);
            $this->productStockService->recordProductionStock($production, $userId);

            return $production->fresh(['product', 'location', 'productionIngredients', 'productionPackagings']);
        });
    }

    /**
     * Sets sind Bündel aus Einzelprodukten und werden nicht produziert.
     */
    public function assertNotASet(Product $product): void
    {
        if ($product->is_set) {
            throw ValidationException::withMessages([
                'product_id' => __('Sets können nicht produziert werden. Bitte ein Einzelprodukt wählen.'),
            ]);
        }
    }

    /**
     * Produktion basiert ausschließlich auf der Hersteller-Rezeptur (kein Fallback auf die Produkt-Rezeptur).
     */
    public function assertManufacturerRecipe(Product $product): void
    {
        $product->loadMissing('manufacturer_ingredients');

        if ($product->manufacturer_ingredients->isEmpty()) {
            throw ValidationException::withMessages([
                'product_id' => __('Für dieses Produkt ist keine Hersteller-Rezeptur gepflegt. Eine Produktion ist erst möglich, wenn eine Hersteller-Rezeptur hinterlegt wurde.'),
            ]);
        }
    }

    /**
     * @param  array<int, float>  $requiredGrams
     * @param  array<int, array{ingredient_id: int, stock_entry_id: int, quantity_used?: mixed}>  $ingredientLines
     */
    private function assertLinesMatchRecipe(array $requiredGrams, array $ingredientLines): void
    {
        $sums = [];
        foreach ($ingredientLines as $line) {
            $iid = (int) $line['ingredient_id'];
            $used = $this->parseQuantity($line['quantity_used'] ?? null);
            $sums[$iid] = ($sums[$iid] ?? 0) + $used;
        }

        foreach ($requiredGrams as $iid => $req) {
            $sum = $sums[$iid] ?? 0;
            if (abs($sum - $req) > 0.02) {
                throw ValidationException::withMessages([
                    'ingredient_lines' => __('Summe der Chargen-Mengen pro INCI muss dem Soll-Verbrauch entsprechen (INCI :id: Soll :req g, Ist :sum g).', [
                        'id' => $iid,
                        'req' => number_format($req, 2, ',', '.'),
                        'sum' => number_format($sum, 2, ',', '.'),
                    ]),
                ]);
            }
        }

        foreach ($sums as $iid => $_sum) {
            if (! isset($requiredGrams[$iid])) {
                throw ValidationException::withMessages([
                    'ingredient_lines' => __('Unerwarteter Inhaltsstoff in den Chargen-Zeilen.'),
                ]);
            }
        }
    }

    private function syncPackagingSnapshot(Production $production, Product $product, int $producedQty): void
    {
        foreach ($product->packagings as $bom) {
            $perUnit = (float) ($bom->pivot->quantity ?? 1);
            $pieces = (int) round($perUnit * $producedQty);
            if ($pieces < 1) {
                $pieces = 1;
            }
            $production->productionPackagings()->create([
                'packaging_item_id' => $bom->id,
                'quantity_used' => $pieces,
            ]);
        }
    }

    /**
     * @return array<int, float>
     */
    public function requiredGramsByIngredient(Product $product, int $producedQuantity): array
    {
        $required = [];
        foreach ($product->manufacturer_ingredients as $ing) {
            $gram = $ing->pivot->gram;
            if ($gram === null || $gram === '') {
                throw ValidationException::withMessages([
                    'product_id' => __('Für „:name“ fehlt der Anteil (%) in der Hersteller-Rezeptur.', ['name' => $ing->name]),
                ]);
            }
            $factor = (float) ($ing->pivot->factor ?? 1.1);
            $required[(int) $ing->id] = (float) $gram * $factor * $producedQuantity;
        }

        return $required;
    }

    /**
     * @param  array{ingredient_id: int, stock_entry_id: int, quantity_used?: mixed}  $line
     */
    public function assertStockEntryMatchesLine(array $line, int $locationId): void
    {
        $entry = StockEntry::query()->findOrFail((int) $line['stock_entry_id']);
        if ($entry->status !== 'received') {
            throw ValidationException::withMessages([
                'ingredient_lines' => __('Wareneingang :id ist nicht als eingegangen gebucht.', ['id' => $entry->id]),
            ]);
        }
        if ((int) $entry->ingredient_id !== (int) $line['ingredient_id']) {
            throw ValidationException::withMessages(['ingredient_lines' => __('Charge passt nicht zum Inhaltsstoff.')]);
        }
        if ((int) $entry->location_id !== $locationId) {
            throw ValidationException::withMessages(['ingredient_lines' => __('Charge gehört zu einem anderen Lagerort.')]);
        }
    }

    /**
     * @param  array<int, array{ingredient_id: int, stock_entry_id: int, quantity_used?: mixed}>  $ingredientLines
     */
    public function computeMhdWarning(Product $product, string $producedAt, array $ingredientLines): bool
    {
        if ($product->shelf_life_type !== 'fixed' || ! $product->shelf_life_months) {
            return false;
        }

        $productEnd = Carbon::parse($producedAt)->addMonths((int) $product->shelf_life_months)->startOfDay();

        foreach ($ingredientLines as $line) {
            $entry = StockEntry::query()->find((int) $line['stock_entry_id']);
            if (! $entry || ! $entry->best_before) {
                continue;
            }
            if ($entry->best_before->lt($productEnd)) {
                return true;
            }
        }

        return false;
    }

    /**
     * Verbrauchte Menge je Wareneingang (über alle Produktionen), optional ohne eine bestimmte Produktion.
     *
     * @param  array<int, int>  $stockEntryIds
     * @return array<int, float>
     */
    public function consumedByStockEntry(array $stockEntryIds, ?int $excludeProductionId = null): array
    {
        if ($stockEntryIds === []) {
            return [];
        }

        $rows = ProductionIngredient::query()
            ->selectRaw('stock_entry_id, SUM(quantity_used) as used')
            ->whereIn('stock_entry_id', $stockEntryIds)
            ->when($excludeProductionId !== null, fn ($q) => $q->where('production_id', '!=', $excludeProductionId))
            ->groupBy('stock_entry_id')
            ->pluck('used', 'stock_entry_id');

        $result = [];
        foreach ($rows as $stockEntryId => $used) {
            $result[(int) $stockEntryId] = (float) $used;
        }

        return $result;
    }

    /**
     * Wareneingänge eines Inhaltsstoffs am Standort mit Restbestand > 0 (FEFO-Reihenfolge).
     *
     * @return Collection<int, StockEntry>
     */
    public function availableStockEntriesForIngredient(int $ingredientId, int $locationId, ?int $excludeProductionId = null): Collection
    {
        $entries = StockEntry::query()
            ->with('supplier')
            ->where('status', 'received')
            ->where('entry_type', 'ingredient')
            ->where('ingredient_id', $ingredientId)
            ->where('location_id', $locationId)
            ->orderByRaw('best_before is null, best_before asc')
            ->orderBy('id')
            ->get();

        $consumed = $this->consumedByStockEntry($entries->pluck('id')->all(), $excludeProductionId);

        return $entries
            ->map(function (StockEntry $entry) use ($consumed) {
                $received = $entry->received_quantity !== null ? (float) $entry->received_quantity : 0.0;
                $entry->setAttribute('remaining_quantity', round($received - ($consumed[(int) $entry->id] ?? 0.0), 2));

                return $entry;
            })
            ->filter(fn (StockEntry $entry) => (float) $entry->getAttribute('remaining_quantity') > 0.0)
            ->values();
    }

    public function stockEntryLabel(StockEntry $entry): string
    {
        $parts = [];
        $parts[] = $entry->supplier?->name ?: __('Lieferant unbekannt');
        $parts[] = $entry->batch_number ?: ('#'.$entry->id);
        if ($entry->best_before) {
            $parts[] = $entry->best_before->format('d.m.Y');
        }

        return implode(' - ', $parts);
    }

    /**
     * @return array<string, mixed>
     */
    public function buildRecipePayload(Product $product, int $locationId, int $productionQuantity, ?int $excludeProductionId = null): array
    {
        $product->loadMissing(['manufacturer_ingredients', 'packagings.packagingMaterial']);

        $qty = max(1, $productionQuantity);
        $recipeRequired = ! (bool) $product->no_recipe_required;
        $hasRecipe = $product->manufacturer_ingredients->isNotEmpty();

        $ingredients = [];
        foreach ($product->manufacturer_ingredients as $ing) {
            $gram = $ing->pivot->gram;
            $factor = (float) ($ing->pivot->factor ?? 1.1);
            $hasGram = $gram !== null && $gram !== '';
            $req = $hasGram ? (float) $gram * $factor * $qty : null;
            $ingredients[] = [
                'id' => $ing->id,
                'name' => $ing->name,
                'gram' => $hasGram ? (float) $gram : null,
                'factor' => $factor,
                'required_grams_total' => $req,
                'stock_entries' => $this->availableStockEntriesForIngredient((int) $ing->id, $locationId, $excludeProductionId)
                    ->map(function (StockEntry $se) {
                        return [
                            'id' => $se->id,
                            'label' => $this->stockEntryLabel($se),
                            'batch_number' => $se->batch_number,
                            'best_before' => $se->best_before?->format('Y-m-d'),
                            'remaining' => (float) $se->getAttribute('remaining_quantity'),
                        ];
                    })->values()->all(),
            ];
        }

        $packagings = [];
        foreach ($product->packagings as $pk) {
            $perUnit = (float) ($pk->pivot->quantity ?? 1);
            $packagings[] = [
                'id' => $pk->id,
                'name' => $pk->name,
                'quantity_per_product' => $perUnit,
                'total_pieces' => (int) round($perUnit * $qty),
                'weight_grams' => $pk->weight_grams !== null ? (float) $pk->weight_grams : null,
                'material_name' => $pk->packagingMaterial?->name,
            ];
        }

        return [
            'product' => [
                'id' => $product->id,
                'name' => $product->name,
                'shelf_life_type' => $product->shelf_life_type,
                'shelf_life_months' => $product->shelf_life_months,
            ],
            'recipe_required' => $recipeRequired,
            'has_recipe' => $hasRecipe,
            'location_id' => $locationId,
            'production_quantity' => $qty,
            'ingredients' => $ingredients,
            'packagings' => $packagings,
        ];
    }

    private function parseQuantity(mixed $value): float
    {
        if ($value === null || $value === '') {
            return 0.0;
        }
        if (is_numeric($value)) {
            return (float) $value;
        }

        $n = reFormatNumber((string) $value);

        return $n !== null && $n !== '' ? (float) $n : 0.0;
    }
}