<?php

namespace Modules\ProjectManagement\Services;

use Modules\ProjectManagement\Models\Project;
use Modules\ProjectManagement\Enums\ProjectStatus;

class ProjectWorkflowService
{
    /**
     * Determine the current structural state of the project.
     * Enforces the sequence: Planning -> Estimated -> Scheduled -> Procuring -> InProgress
     */
    public function getProjectWorkflowState(Project $project): string
    {
        $hasEstimates = $project->materialsEstimates()->exists();
        $hasTasks = $project->tasks()->exists();
        
        if ($project->status === ProjectStatus::Completed || $project->status === ProjectStatus::Closed) {
            return $project->status->value;
        }

        if ($project->status === ProjectStatus::InProgress) {
            return 'in_progress';
        }

        if (!$hasEstimates) {
            return 'planning'; // Step 1: Project Creation / Planning
        }

        if (!$hasTasks) {
            return 'estimated'; // Step 2: Materials Estimated, Tasks not yet scheduled
        }

        // Has estimates and tasks, check if procurement (MR/PO) has occurred
        return 'scheduled'; // Step 3: Tasks Scheduled & Resources assigned
    }

    /**
     * Guard: check if Material Requisitions can be created for this project.
     * Enforced strictly: Must have estimates and tasks first.
     */
    public function canCreateRequisition(Project $project): bool
    {
        $state = $this->getProjectWorkflowState($project);
        
        // Allowed if project is scheduled, procuring, or in progress
        return in_array($state, ['scheduled', 'procuring', 'in_progress']) || 
               $project->status === ProjectStatus::InProgress;
    }

    /**
     * Guard: check if Purchase Orders can be created.
     * Enforced strictly: Requires an approved material requisition for the project.
     */
    public function canCreatePurchaseOrder(Project $project): bool
    {
        // Requisition must exist and be approved for this project
        $hasApprovedMr = \Modules\MaterialLogistics\Models\MaterialRequisition::where('project_id', $project->id)
            ->where('status', 'approved')
            ->exists();

        return $hasApprovedMr || $project->status === ProjectStatus::InProgress;
    }

    /**
     * Retrieve the budget analysis for a project (Estimated vs. Requisitioned vs. PO value)
     */
    public function getBudgetAnalysis(Project $project): array
    {
        $estimatedValue = $project->materialsEstimates->sum(fn ($est) => (float) $est->estimated_qty * (float) $est->unit_cost);
        
        // Sum labor & equipment estimates
        $laborEstimates = 0.00;
        $equipmentEstimates = 0.00;
        foreach ($project->tasks as $task) {
            $laborEstimates += $task->estimated_labor_cost;
            $equipmentEstimates += $task->estimated_equipment_cost;
        }

        $totalEstimated = $estimatedValue + $laborEstimates + $equipmentEstimates;

        // Sum actual PO costs for warehouses belonging to this project
        $poTotal = 0.00;
        $warehouseIds = \Modules\MaterialLogistics\Models\Warehouse::where('project_id', $project->id)->pluck('id');
        if ($warehouseIds->isNotEmpty()) {
            $poTotal = (float) \Modules\MaterialLogistics\Models\PurchaseOrder::whereIn('target_warehouse_id', $warehouseIds)
                ->whereIn('status', ['approved', 'delivered'])
                ->get()
                ->sum('total_cost');
        }

        return [
            'contract_value' => (float) $project->contract_value,
            'materials_estimated' => $estimatedValue,
            'labor_estimated' => $laborEstimates,
            'equipment_estimated' => $equipmentEstimates,
            'total_estimated' => $totalEstimated,
            'po_total' => $poTotal,
            'remaining_estimate' => max(0.00, $totalEstimated - $poTotal),
            'is_over_budget' => $poTotal > $totalEstimated || $project->rollup_capitalization > $project->rollup_contract_value,
        ];
    }
}