<?php

namespace App\Services;

use App\Mail\FinanceDocumentApprovedByAccountant;
use App\Mail\FinanceDocumentFullyApproved;
use App\Mail\FinanceDocumentRejected;
use App\Models\FinanceDocument;
use App\Models\User;
use App\Support\AuditLogger;
use Illuminate\Support\Facades\Mail;

/**
 * Service for handling FinanceDocument approval workflow.
 *
 * Workflow: Secretary → Chair → Board (based on amount tier)
 * - Small (<5,000): Secretary only
 * - Medium (5,000-50,000): Secretary → Chair
 * - Large (>50,000): Secretary → Chair → Board
 */
class FinanceDocumentApprovalService
{
    /**
     * Approve by Secretary (first stage)
     */
    public function approveBySecretary(FinanceDocument $document, User $user): array
    {
        if (! $document->canBeApprovedBySecretary($user)) {
            return ['success' => false, 'message' => '無法在此階段進行秘書長審核。'];
        }

        $document->update([
            'approved_by_secretary_id' => $user->id,
            'secretary_approved_at' => now(),
            'status' => FinanceDocument::STATUS_APPROVED_SECRETARY,
        ]);

        AuditLogger::log('finance_document.approved_by_secretary', $document, [
            'approved_by' => $user->name,
            'amount_tier' => $document->amount_tier,
        ]);

        // Small amount: approval complete
        if ($document->amount_tier === FinanceDocument::AMOUNT_TIER_SMALL) {
            $this->notifySubmitter($document);

            return [
                'success' => true,
                'message' => '秘書長已核准。小額申請審核完成，申請人可向出納領款。',
                'complete' => true,
            ];
        }

        // Medium/Large: notify chairs
        $this->notifyNextApprovers($document, 'finance_chair');

        return [
            'success' => true,
            'message' => '秘書長已核准。已送交理事長審核。',
            'complete' => false,
        ];
    }

    /**
     * Approve by Chair (second stage)
     */
    public function approveByChair(FinanceDocument $document, User $user): array
    {
        if (! $document->canBeApprovedByChair($user)) {
            return ['success' => false, 'message' => '無法在此階段進行理事長審核。'];
        }

        $document->update([
            'approved_by_chair_id' => $user->id,
            'chair_approved_at' => now(),
            'status' => FinanceDocument::STATUS_APPROVED_CHAIR,
        ]);

        AuditLogger::log('finance_document.approved_by_chair', $document, [
            'approved_by' => $user->name,
            'amount_tier' => $document->amount_tier,
        ]);

        // Medium amount: approval complete
        if ($document->amount_tier === FinanceDocument::AMOUNT_TIER_MEDIUM) {
            $this->notifySubmitter($document);

            return [
                'success' => true,
                'message' => '理事長已核准。中額申請審核完成，申請人可向出納領款。',
                'complete' => true,
            ];
        }

        // Large: notify board members
        $this->notifyNextApprovers($document, 'finance_board_member');

        return [
            'success' => true,
            'message' => '理事長已核准。大額申請需送交董理事會審核。',
            'complete' => false,
        ];
    }

    /**
     * Approve by Board (third stage)
     */
    public function approveByBoard(FinanceDocument $document, User $user): array
    {
        if (! $document->canBeApprovedByBoard($user)) {
            return ['success' => false, 'message' => '無法在此階段進行董理事會審核。'];
        }

        $document->update([
            'board_meeting_approved_by_id' => $user->id,
            'board_meeting_approved_at' => now(),
            'status' => FinanceDocument::STATUS_APPROVED_BOARD,
        ]);

        AuditLogger::log('finance_document.approved_by_board', $document, [
            'approved_by' => $user->name,
            'amount_tier' => $document->amount_tier,
        ]);

        $this->notifySubmitter($document);

        return [
            'success' => true,
            'message' => '董理事會已核准。審核流程完成，申請人可向出納領款。',
            'complete' => true,
        ];
    }

    /**
     * Reject document at any stage
     */
    public function reject(FinanceDocument $document, User $user, string $reason): array
    {
        if ($document->isRejected()) {
            return ['success' => false, 'message' => '此申請已被駁回。'];
        }

        $document->update([
            'status' => FinanceDocument::STATUS_REJECTED,
            'rejected_by_user_id' => $user->id,
            'rejected_at' => now(),
            'rejection_reason' => $reason,
        ]);

        AuditLogger::log('finance_document.rejected', $document, [
            'rejected_by' => $user->name,
            'reason' => $reason,
        ]);

        // Notify submitter
        if ($document->submittedBy) {
            Mail::to($document->submittedBy->email)->queue(new FinanceDocumentRejected($document));
        }

        return [
            'success' => true,
            'message' => '申請已駁回。',
        ];
    }

    /**
     * Process approval based on user role
     */
    public function processApproval(FinanceDocument $document, User $user): array
    {
        $isSecretary = $user->hasRole('secretary_general');
        $isChair = $user->hasRole('finance_chair');
        $isBoardMember = $user->hasRole('finance_board_member');
        $isAdmin = $user->hasRole('admin');

        // Secretary approval
        if ($document->canBeApprovedBySecretary($user) && ($isSecretary || $isAdmin)) {
            return $this->approveBySecretary($document, $user);
        }

        // Chair approval
        if ($document->canBeApprovedByChair($user) && ($isChair || $isAdmin)) {
            return $this->approveByChair($document, $user);
        }

        // Board approval
        if ($document->canBeApprovedByBoard($user) && ($isBoardMember || $isAdmin)) {
            return $this->approveByBoard($document, $user);
        }

        return ['success' => false, 'message' => '您無權在此階段審核此文件。'];
    }

    /**
     * Notify submitter that approval is complete
     */
    protected function notifySubmitter(FinanceDocument $document): void
    {
        if ($document->submittedBy) {
            Mail::to($document->submittedBy->email)->queue(new FinanceDocumentFullyApproved($document));
        }
    }

    /**
     * Notify next approvers in workflow
     */
    protected function notifyNextApprovers(FinanceDocument $document, string $roleName): void
    {
        $approvers = User::role($roleName)->get();
        foreach ($approvers as $approver) {
            Mail::to($approver->email)->queue(new FinanceDocumentApprovedByAccountant($document));
        }
    }
}