<?php

namespace App\Services;

use Modules\Formation\Entities\Formation;
use Illuminate\Database\Eloquent\Builder;

class VisibilityService
{
    /**
     * Apply visibility scoping to a query builder based on user permissions
     *
     * @param bool $includeUnitsWithoutFormation When true (process models), SEL PERO 91 REJ
     *        users can see units without formations. Government users never see units without formations.
     */
    public function applyVisibilityToQuery(Builder $query, $user, string $unitColumn = 'unit_id', bool $includeUnitsWithoutFormation = false): Builder
    {
        // Check if user has akses peringkat keseluruhan permission (super admin)
        if ($user->can('akses peringkat keseluruhan', Unit::class)) {
            return $query;
        }

        // Get user's unit
        $userUnit = Unit::find($user->unit_id);
        if (!$userUnit) {
            return $query->whereRaw('1 = 0');
        }

        // Government permission: Can view all units under their government
        // Government users do NOT see units without formations
        // SEL PERO 91 REJ (process models): ONLY see units without formation - not their gov/formation units
        if ($user->can('akses peringkat formasi')) {
            if ($includeUnitsWithoutFormation && $user->hasRole('SEL PERO 91 REJ')) {
                $unitIds = Unit::whereNull('formation_id')
                    ->whereNull('repair_formation_id')
                    ->pluck('id')
                    ->toArray();
            } else {
                $unitIds = $this->getUnitsUnderGovernment($userUnit);
                $unitIds = $this->excludeUnitsWithoutFormation($unitIds);
            }

            if (!empty($unitIds)) {
                return $query->whereIn($unitColumn, $unitIds);
            }
            return $query->whereRaw('1 = 0');
        }

        // DIV permission: Can view all units under their formation (including repair formations)
        if ($user->can('akses peringkat divisyen')) {
            $unitIds = $this->getVisibleUnitIdsForFormationUser($user, $userUnit, $includeUnitsWithoutFormation);

            if (!empty($unitIds)) {
                return $query->whereIn($unitColumn, $unitIds);
            }
            return $query->whereRaw('1 = 0');
        }

        // Unit permission: Can only view data within their unit
        return $query->where($unitColumn, $user->unit_id);
    }

    /**
     * Apply visibility scoping for models with indirect unit relationships
     *
     * @param bool $includeUnitsWithoutFormation When true (process models), SEL PERO 91 REJ
     *        users can see units without formations. Government users never see units without formations.
     */
    public function applyVisibilityToIndirectQuery(Builder $query, $user, array $unitRelationship, bool $includeUnitsWithoutFormation = false): Builder
    {
        // Check if user has akses peringkat keseluruhan permission (super admin)
        if ($user->can('akses peringkat keseluruhan', Unit::class)) {
            return $query;
        }

        // Get user's unit
        $userUnit = Unit::find($user->unit_id);
        if (!$userUnit) {
            return $query->whereRaw('1 = 0');
        }

        // Government permission: Can view all units under their government
        // SEL PERO 91 REJ (process models): ONLY see units without formation - not their gov/formation units
        if ($user->can('akses peringkat formasi')) {
            if ($includeUnitsWithoutFormation && $user->hasRole('SEL PERO 91 REJ')) {
                $unitIds = Unit::whereNull('formation_id')
                    ->whereNull('repair_formation_id')
                    ->pluck('id')
                    ->toArray();
            } else {
                $unitIds = $this->getUnitsUnderGovernment($userUnit);
                $unitIds = $this->excludeUnitsWithoutFormation($unitIds);
            }

            if (!empty($unitIds)) {
                return $query->whereHas($unitRelationship['relationship'], function ($subQuery) use ($unitIds, $unitRelationship) {
                    $subQuery->whereIn($unitRelationship['unitColumn'], $unitIds);
                });
            }
            return $query->whereRaw('1 = 0');
        }

        // DIV permission: Can view all units under their formation (including repair formations)
        if ($user->can('akses peringkat divisyen')) {
            $unitIds = $this->getVisibleUnitIdsForFormationUser($user, $userUnit, $includeUnitsWithoutFormation);

            if (!empty($unitIds)) {
                return $query->whereHas($unitRelationship['relationship'], function ($subQuery) use ($unitIds, $unitRelationship) {
                    $subQuery->whereIn($unitRelationship['unitColumn'], $unitIds);
                });
            }
            return $query->whereRaw('1 = 0');
        }

        // Unit permission: Can only view data within their unit
        return $query->whereHas($unitRelationship['relationship'], function ($subQuery) use ($user, $unitRelationship) {
            $subQuery->where($unitRelationship['unitColumn'], $user->unit_id);
        });
    }

    /**
     * Get all units under the same government as the user's unit
     * Handles both direct government relationships and formation-government relationships
     * Priority: Direct government_id takes precedence over formation government
     * 
     * @param Unit $userUnit
     * @return array
     */
    public function getUnitsUnderGovernment(Unit $userUnit): array
    {
        $unitIds = collect();

        // Case 1: User's unit has direct government relationship (HIGHEST PRIORITY)
        if ($userUnit->government_id) {
            $directUnits = Unit::where('government_id', $userUnit->government_id)
                ->pluck('id');
            $unitIds = $unitIds->merge($directUnits);
            
            // Also get units in formations under the same direct government
            $formationUnits = Unit::whereHas('formation', function ($query) use ($userUnit) {
                $query->where('government_id', $userUnit->government_id);
            })->pluck('id');
            $unitIds = $unitIds->merge($formationUnits);
            
            return $unitIds->unique()->toArray();
        }

        // Case 2: User's unit belongs to a formation that has a government (FALLBACK)
        if ($userUnit->formation_id) {
            $formation = Formation::find($userUnit->formation_id);
            if ($formation && $formation->government_id) {
                // Get all units in formations under the same government
                $formationUnits = Unit::whereHas('formation', function ($query) use ($formation) {
                    $query->where('government_id', $formation->government_id);
                })->pluck('id');
                $unitIds = $unitIds->merge($formationUnits);

                // Also get direct government units under the same government
                $directGovUnits = Unit::where('government_id', $formation->government_id)
                    ->pluck('id');
                $unitIds = $unitIds->merge($directGovUnits);
            }
        }

        return $unitIds->unique()->toArray();
    }

    /**
     * Get the repair formation ID for a unit
     * Priority: repair_formation_id > formation_id > null
     * 
     * @param Unit $unit
     * @return int|null
     */
    public function getRepairFormationId(Unit $unit): ?int
    {
        // Priority 1: Check repair_formation_id (custom repair formation)
        if ($unit->repair_formation_id) {
            return $unit->repair_formation_id;
        }
        
        // Priority 2: Fall back to regular formation_id
        if ($unit->formation_id) {
            return $unit->formation_id;
        }
        
        // Priority 3: No formation (government-level only)
        return null;
    }

    /**
     * Get visible unit IDs for a user
     *
     * @param bool $includeUnitsWithoutFormation When true (process models), SEL PERO 91 REJ
     *        users can see units without formations. Government users never see units without formations.
     */
    public function getVisibleUnitIds($user, bool $includeUnitsWithoutFormation = false): array
    {
        // Check if user has akses peringkat keseluruhan permission (super admin)
        if ($user->can('akses peringkat keseluruhan', Unit::class)) {
            return Unit::pluck('id')->toArray();
        }

        // Get user's unit
        $userUnit = Unit::find($user->unit_id);
        if (!$userUnit) {
            return [];
        }

        // Government permission: Can view all units under their government
        // SEL PERO 91 REJ (process models): ONLY see units without formation - not their gov/formation units
        if ($user->can('akses peringkat formasi')) {
            if ($includeUnitsWithoutFormation && $user->hasRole('SEL PERO 91 REJ')) {
                return Unit::whereNull('formation_id')
                    ->whereNull('repair_formation_id')
                    ->pluck('id')
                    ->toArray();
            }
            $unitIds = $this->getUnitsUnderGovernment($userUnit);
            return $this->excludeUnitsWithoutFormation($unitIds);
        }

        // DIV permission: Can view all units under their formation (including repair formations)
        if ($user->can('akses peringkat divisyen')) {
            return $this->getVisibleUnitIdsForFormationUser($user, $userUnit, $includeUnitsWithoutFormation);
        }

        // Unit permission: Can only view data within their unit
        return [$user->unit_id];
    }

    /**
     * Exclude units that have no formation (both formation_id and repair_formation_id are null).
     * Government users do not see these units.
     */
    protected function excludeUnitsWithoutFormation(array $unitIds): array
    {
        if (empty($unitIds)) {
            return [];
        }

        return Unit::whereIn('id', $unitIds)
            ->where(function ($q) {
                $q->whereNotNull('formation_id')
                  ->orWhereNotNull('repair_formation_id');
            })
            ->pluck('id')
            ->toArray();
    }

    /**
     * Get visible unit IDs for a user with akses peringkat divisyen permission.
     *
     * Asset view (includeUnitsWithoutFormation=false): Only units where formation_id matches.
     * Excludes units that have repair_formation_id but formation_id null (e.g. 10 SKN RAJD uses
     * 3 DIV for repair only - 3 DIV users see their repairs but NOT their asset data).
     *
     * Process view (includeUnitsWithoutFormation=true): Units where repair_formation_id OR
     * formation_id matches. SEL PERO 91 REJ also sees units without any formation.
     */
    protected function getVisibleUnitIdsForFormationUser($user, Unit $userUnit, bool $includeUnitsWithoutFormation): array
    {
        $userRepairFormationId = $this->getRepairFormationId($userUnit);

        if ($userRepairFormationId) {
            if (!$includeUnitsWithoutFormation) {
                // Asset view: Only units that belong to the formation (formation_id matches).
                // Exclude units that use formation only for repair (formation_id null, repair_formation_id set).
                return Unit::where('formation_id', $userRepairFormationId)
                    ->pluck('id')
                    ->toArray();
            }

            // SEL PERO 91 REJ: ONLY see units without formation - not their formation's units
            // (formation units are handled by SEL PERO DIV)
            if ($user->hasRole('SEL PERO 91 REJ')) {
                return Unit::whereNull('formation_id')
                    ->whereNull('repair_formation_id')
                    ->pluck('id')
                    ->toArray();
            }

            // Process view: Units in user's formation (repair_formation_id or formation_id)
            return Unit::where(function ($q) use ($userRepairFormationId) {
                $q->where('repair_formation_id', $userRepairFormationId)
                  ->orWhere(function ($q2) use ($userRepairFormationId) {
                      $q2->whereNull('repair_formation_id')
                         ->where('formation_id', $userRepairFormationId);
                  });
            })->pluck('id')->toArray();
        }

        // User's unit has no formation - check if they have SEL PERO 91 REJ (process models only)
        if ($includeUnitsWithoutFormation && $user->hasRole('SEL PERO 91 REJ')) {
            return Unit::whereNull('formation_id')
                ->whereNull('repair_formation_id')
                ->pluck('id')
                ->toArray();
        }

        return [];
    }
}