<?php

namespace App\Http\Controllers;

use App\Actions\CreateBucketAction;
use App\Models\Bucket;
use App\Models\Scenario;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;
use InvalidArgumentException;

class BucketController extends Controller
{
    public function index(Scenario $scenario): JsonResponse
    {
        $buckets = $scenario->buckets()
            ->orderedBySortOrder()
            ->get()
            ->map(function ($bucket) {
                return [
                    'id' => $bucket->id,
                    'name' => $bucket->name,
                    'priority' => $bucket->priority,
                    'sort_order' => $bucket->sort_order,
                    'allocation_type' => $bucket->allocation_type,
                    'allocation_value' => $bucket->allocation_value,
                    'allocation_type_label' => $bucket->getAllocationTypeLabel(),
                    'formatted_allocation_value' => $bucket->getFormattedAllocationValue(),
                    'current_balance' => $bucket->getCurrentBalance(),
                    'has_available_space' => $bucket->hasAvailableSpace(),
                    'available_space' => $bucket->getAvailableSpace(),
                ];
            });

        return response()->json([
            'buckets' => $buckets
        ]);
    }

    public function store(Request $request, Scenario $scenario): JsonResponse
    {
        $validated = $request->validate([
            'name' => 'required|string|max:255',
            'allocation_type' => 'required|in:' . implode(',', [
                Bucket::TYPE_FIXED_LIMIT,
                Bucket::TYPE_PERCENTAGE,
                Bucket::TYPE_UNLIMITED,
            ]),
            'allocation_value' => 'nullable|numeric',
            'priority' => 'nullable|integer|min:1',
        ]);

        try {
            $createBucketAction = new CreateBucketAction();
            $bucket = $createBucketAction->execute(
                $scenario,
                $validated['name'],
                $validated['allocation_type'],
                $validated['allocation_value'],
                $validated['priority'] ?? null
            );

            return response()->json([
                'bucket' => $this->formatBucketResponse($bucket),
                'message' => 'Bucket created successfully.'
            ], 201);
        } catch (InvalidArgumentException $e) {
            return response()->json([
                'message' => 'Validation failed.',
                'errors' => ['allocation_value' => [$e->getMessage()]]
            ], 422);
        }
    }

    public function update(Request $request, Bucket $bucket): JsonResponse
    {
        $validated = $request->validate([
            'name' => 'required|string|max:255',
            'allocation_type' => 'required|in:' . implode(',', [
                Bucket::TYPE_FIXED_LIMIT,
                Bucket::TYPE_PERCENTAGE,
                Bucket::TYPE_UNLIMITED,
            ]),
            'allocation_value' => 'nullable|numeric',
            'priority' => 'nullable|integer|min:1',
        ]);

        // Validate allocation_value based on allocation_type
        $allocationValueRules = Bucket::allocationValueRules($validated['allocation_type']);
        $request->validate([
            'allocation_value' => $allocationValueRules,
        ]);

        // Set allocation_value to null for unlimited buckets
        if ($validated['allocation_type'] === Bucket::TYPE_UNLIMITED) {
            $validated['allocation_value'] = null;
        }

        // Handle priority change if needed
        if (isset($validated['priority']) && $validated['priority'] !== $bucket->priority) {
            $this->updateBucketPriority($bucket, $validated['priority']);
            $validated['sort_order'] = $validated['priority'];
        }

        $bucket->update($validated);

        return response()->json([
            'bucket' => $this->formatBucketResponse($bucket),
            'message' => 'Bucket updated successfully.'
        ]);
    }

    /**
     * Remove the specified bucket.
     */
    public function destroy(Bucket $bucket): JsonResponse
    {
        $scenarioId = $bucket->scenario_id;
        $deletedPriority = $bucket->priority;

        $bucket->delete();

        // Shift remaining priorities down to fill the gap
        $this->shiftPrioritiesDown($scenarioId, $deletedPriority);

        return response()->json([
            'message' => 'Bucket deleted successfully.'
        ]);
    }

    /**
     * Update bucket priorities (for drag-and-drop reordering).
     */
    public function updatePriorities(Request $request, Scenario $scenario): JsonResponse
    {
        $validated = $request->validate([
            'bucket_priorities' => 'required|array',
            'bucket_priorities.*.id' => 'required|exists:buckets,id',
            'bucket_priorities.*.priority' => 'required|integer|min:1',
        ]);

        foreach ($validated['bucket_priorities'] as $bucketData) {
            $bucket = Bucket::find($bucketData['id']);
            if ($bucket && $bucket->scenario_id === $scenario->id) {
                $bucket->update([
                    'priority' => $bucketData['priority'],
                    'sort_order' => $bucketData['priority'],
                ]);
            }
        }

        return response()->json([
            'message' => 'Bucket priorities updated successfully.'
        ]);
    }

    /**
     * Format bucket data for JSON response.
     */
    private function formatBucketResponse(Bucket $bucket): array
    {
        return [
            'id' => $bucket->id,
            'name' => $bucket->name,
            'priority' => $bucket->priority,
            'sort_order' => $bucket->sort_order,
            'allocation_type' => $bucket->allocation_type,
            'allocation_value' => $bucket->allocation_value,
            'allocation_type_label' => $bucket->getAllocationTypeLabel(),
            'formatted_allocation_value' => $bucket->getFormattedAllocationValue(),
            'current_balance' => $bucket->getCurrentBalance(),
            'has_available_space' => $bucket->hasAvailableSpace(),
            'available_space' => $bucket->getAvailableSpace(),
        ];
    }


    /**
     * Shift priorities down to fill gap after deletion.
     */
    private function shiftPrioritiesDown(int $scenarioId, int $deletedPriority): void
    {
        Bucket::query()
            ->where('scenario_id', $scenarioId)
            ->where('priority', '>', $deletedPriority)
            ->decrement('priority');
    }

    /**
     * Update a bucket's priority and adjust other buckets accordingly.
     */
    private function updateBucketPriority(Bucket $bucket, int $newPriority): void
    {
        $oldPriority = $bucket->priority;
        $scenario = $bucket->scenario;

        if ($newPriority === $oldPriority) {
            return;
        }

        // Use database transaction to handle constraint conflicts
        DB::transaction(function () use ($bucket, $scenario, $oldPriority, $newPriority) {
            // Temporarily set the moving bucket to a high priority to avoid conflicts
            $tempPriority = $scenario->buckets()->max('priority') + 100;
            $bucket->update(['priority' => $tempPriority]);

            if ($newPriority < $oldPriority) {
                // Moving up - shift others down
                $scenario->buckets()
                    ->where('id', '!=', $bucket->id)
                    ->whereBetween('priority', [$newPriority, $oldPriority - 1])
                    ->increment('priority');
            } else {
                // Moving down - shift others up
                $scenario->buckets()
                    ->where('id', '!=', $bucket->id)
                    ->whereBetween('priority', [$oldPriority + 1, $newPriority])
                    ->decrement('priority');
            }

            // Finally, set the bucket to its new priority
            $bucket->update(['priority' => $newPriority]);
        });
    }
}