<?php

namespace App\Http\Controllers;

use App\Models\Account;
use App\Models\Client;
use App\Models\Contract;
use App\Models\Import;
use App\Models\ImportEvent;
use App\Models\ImportTemplate;
use App\Services\CsvImportService;
use App\Services\ImportProcessor;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Storage;
use Illuminate\Support\Str;
use Inertia\Inertia;

class ImportController extends Controller
{
    // List imports (paginated)
    public function index(Request $request)
    {
        $paginator = Import::query()
            ->with([
                'client:id,uuid,person_id',
                'client.person:id,uuid,full_name',
                'template:id,name',
            ])
            ->orderByDesc('created_at')
            ->paginate(15);

        $imports = [
            'data' => $paginator->items(),
            'links' => [
                'first' => $paginator->url(1),
                'last' => $paginator->url($paginator->lastPage()),
                'prev' => $paginator->previousPageUrl(),
                'next' => $paginator->nextPageUrl(),
            ],
            'meta' => [
                'current_page' => $paginator->currentPage(),
                'from' => $paginator->firstItem(),
                'last_page' => $paginator->lastPage(),
                'path' => $paginator->path(),
                'per_page' => $paginator->perPage(),
                'to' => $paginator->lastItem(),
                'total' => $paginator->total(),
            ],
        ];
        // Map items into a simpler shape
        $imports['data'] = array_map(function ($imp) {
            return [
                'id' => $imp->id,
                'uuid' => $imp->uuid,
                'created_at' => $imp->created_at,
                'original_name' => $imp->original_name,
                'size' => $imp->size,
                'status' => $imp->status,
                'client' => $imp->client ? [
                    'id' => $imp->client_id,
                    'uuid' => $imp->client->uuid,
                    'person' => $imp->client->person ? [
                        'uuid' => $imp->client->person->uuid,
                        'full_name' => $imp->client->person->full_name,
                    ] : null,
                ] : null,
                'template' => $imp->template ? ['id' => $imp->template->id, 'name' => $imp->template->name] : null,
            ];
        }, $imports['data']);

        return Inertia::render('Imports/Index', [
            'imports' => $imports,
        ]);
    }

    // Show the import creation page
    public function create(Request $request)
    {
        $templates = ImportTemplate::query()
            ->leftJoin('clients', 'clients.id', '=', 'import_templates.client_id')
            ->where('import_templates.is_active', true)
            ->orderBy('import_templates.name')
            ->get([
                'import_templates.id',
                'import_templates.uuid',
                'import_templates.name',
                'import_templates.source_type',
                'import_templates.default_record_type',
                'import_templates.client_id',
                DB::raw('clients.uuid as client_uuid'),
            ]);

        $clients = Client::query()
            ->join('person', 'person.id', '=', 'clients.person_id')
            ->orderBy('person.full_name')
            ->get([
                'clients.id',
                'clients.uuid',
                DB::raw('person.full_name as name'),
            ]);

        return Inertia::render('Imports/Create', [
            'templates' => $templates,
            'clients' => $clients,
            // no existing import on create
        ]);
    }

    // Create a new import job, store file, and return basic info
    public function store(Request $request)
    {
        $validated = $request->validate([
            'file' => 'required|file|max:20480', // 20MB; adjust as needed
            'source_type' => 'nullable|string|in:csv,xml,xls,xlsx,json,txt',
            'sheet_name' => 'nullable|string|max:64',
            'has_header' => 'nullable|boolean',
            'import_template_id' => 'nullable|integer|exists:import_templates,id',
            'client_uuid' => 'nullable|string|exists:clients,uuid',
        ]);

        $file = $validated['file'];
        $ext = strtolower($file->getClientOriginalExtension());
        $sourceType = $validated['source_type'] ?? ($ext === 'txt' ? 'csv' : $ext);

        $uuid = (string) Str::uuid();
        $disk = 'local';
        $path = $file->storeAs('imports', $uuid.'.'.$ext, $disk);

        // Resolve client_uuid to client_id if provided
        $clientId = null;
        if (! empty($validated['client_uuid'] ?? null)) {
            $clientId = Client::where('uuid', $validated['client_uuid'])->value('id');
        }

        $import = Import::create([
            'uuid' => $uuid,
            'user_id' => $request->user()?->id,
            'import_template_id' => $validated['import_template_id'] ?? null,
            'client_id' => $clientId,
            'source_type' => $sourceType,
            'file_name' => basename($path),
            'original_name' => $file->getClientOriginalName(),
            'disk' => $disk,
            'path' => $path,
            'size' => $file->getSize(),
            'sheet_name' => $validated['sheet_name'] ?? null,
            'status' => 'uploaded',
            'show_missing' => false,
            'meta' => [
                'has_header' => $validated['has_header'] ?? true,
            ],
        ]);

        return response()->json([
            'id' => $import->id,
            'uuid' => $import->uuid,
            'status' => $import->status,
            'show_missing' => (bool) ($import->show_missing ?? false),
        ]);
    }

    // Kick off processing of an import - simple synchronous step for now
    public function process(Import $import, Request $request, ImportProcessor $processor)
    {
        $import->update(['status' => 'validating', 'started_at' => now()]);
        $result = $processor->process($import, user: $request->user());

        return response()->json($result);
    }

    // Analyze the uploaded file and return column headers or positional indices
    public function columns(Request $request, Import $import, CsvImportService $csv)
    {
        $validated = $request->validate([
            'has_header' => 'nullable|boolean',
            'delimiter' => 'nullable|string|max:4',
        ]);

        $hasHeader = array_key_exists('has_header', $validated)
            ? (bool) $validated['has_header']
            : (bool) ($import->meta['has_header'] ?? true);

        // Resolve delimiter preference: explicit param > template meta > existing meta > auto-detect
        $explicitDelimiter = null;
        if (array_key_exists('delimiter', $validated) && $validated['delimiter'] !== null && $validated['delimiter'] !== '') {
            $explicitDelimiter = (string) $validated['delimiter'];
        } elseif ($import->import_template_id) {
            // Try reading template meta for a default delimiter
            $tplDelimiter = optional(ImportTemplate::find($import->import_template_id))->meta['delimiter'] ?? null;
            if ($tplDelimiter) {
                $explicitDelimiter = (string) $tplDelimiter;
            }
        } elseif (! empty($import->meta['forced_delimiter'] ?? null)) {
            $explicitDelimiter = (string) $import->meta['forced_delimiter'];
        }

        // Prefer CSV/TXT; if source_type is unknown, attempt best-effort based on file extension
        $treatAsText = in_array($import->source_type, ['csv', 'txt']);
        if (! $treatAsText) {
            $orig = strtolower(pathinfo($import->original_name ?? '', PATHINFO_EXTENSION));
            if (in_array($orig, ['csv', 'txt'])) {
                $treatAsText = true;
            }
        }

        $fullPath = Storage::disk($import->disk)->path($import->path);
        $note = '';
        if ($treatAsText) {
            if ($explicitDelimiter !== null && $explicitDelimiter !== '') {
                $columns = $csv->parseColumnsFromCsv($fullPath, $explicitDelimiter, $hasHeader);
                $delimiter = $explicitDelimiter;
            } else {
                [$delimiter, $columns] = $csv->detectColumnsFromCsv($fullPath, $hasHeader);
                // Backstop: if single column but file clearly has separators, try common ones
                if (is_array($columns) && count($columns) <= 1) {
                    foreach ([';', "\t", '|', ' ', ','] as $try) {
                        $alt = $csv->parseColumnsFromCsv($fullPath, $try, $hasHeader);
                        if (is_array($alt) && count($alt) > 1) {
                            $delimiter = $try;
                            $columns = $alt;
                            $note = 'Delimiter auto-detection backstopped to '.json_encode($try);
                            break;
                        }
                    }
                }
            }
        } else {
            // Best-effort: try detect anyway
            [$delimiter, $columns] = $csv->detectColumnsFromCsv($fullPath, $hasHeader);
        }

        // Save meta
        $meta = $import->meta ?? [];
        $meta['has_header'] = $hasHeader;
        $meta['detected_delimiter'] = $delimiter;
        $meta['columns'] = $columns;
        if ($explicitDelimiter) {
            $meta['forced_delimiter'] = $explicitDelimiter;
        }
        $import->update([
            'meta' => $meta,
            'status' => $import->status === 'uploaded' ? 'parsed' : $import->status,
        ]);

        return response()->json([
            'columns' => $columns,
            'has_header' => $hasHeader,
            'detected_delimiter' => $delimiter,
            'note' => $note,
        ]);
    }

    // CSV helpers moved to App\Services\CsvImportService

    // Save ad-hoc mappings for a specific import (when no template is selected)
    public function saveMappings(Request $request, Import $import)
    {
        $data = $request->validate([
            'mappings' => 'required|array',
            'mappings.*.source_column' => 'required|string',
            'mappings.*.entity' => 'nullable|string|in:person,person_addresses,person_phones,emails,accounts,contracts,client_cases,payments',
            'mappings.*.target_field' => 'required|string',
            'mappings.*.transform' => 'nullable|string|in:trim,upper,lower,decimal,ref',
            'mappings.*.apply_mode' => 'nullable|string|in:insert,update,both,keyref',
            'mappings.*.options' => 'nullable|array',
        ]);

        // Upsert by (import_id, source_column): update existing rows; insert new ones; avoid duplicates
        $now = now();
        $existing = \DB::table('import_mappings')
            ->where('import_id', $import->id)
            ->get(['id', 'source_column', 'position']);

        $bySource = [];
        $dupes = [];
        foreach ($existing as $row) {
            $src = (string) $row->source_column;
            if (! array_key_exists($src, $bySource)) {
                $bySource[$src] = ['id' => $row->id, 'position' => $row->position];
            } else {
                $dupes[$src] = ($dupes[$src] ?? []);
                $dupes[$src][] = $row->id;
            }
        }

        $basePosition = (int) (\DB::table('import_mappings')->where('import_id', $import->id)->max('position') ?? -1);
        $inserted = 0;
        $updated = 0;
        $deduped = 0;

        foreach ($data['mappings'] as $pos => $m) {
            $src = (string) $m['source_column'];
            $payload = [
                'entity' => $m['entity'] ?? null,
                'target_field' => $m['target_field'],
                'transform' => $m['transform'] ?? null,
                'apply_mode' => $m['apply_mode'] ?? 'both',
                'options' => $m['options'] ?? null,
                'position' => $pos, // keep UI order
                'updated_at' => $now,
            ];

            if (array_key_exists($src, $bySource)) {
                // Update first occurrence
                \DB::table('import_mappings')->where('id', $bySource[$src]['id'])->update($payload);
                $updated++;
                // Remove duplicates if any
                if (! empty($dupes[$src])) {
                    $deleted = \DB::table('import_mappings')->whereIn('id', $dupes[$src])->delete();
                    $deduped += (int) $deleted;
                    unset($dupes[$src]);
                }
            } else {
                // Insert new
                \DB::table('import_mappings')->insert([
                    'import_id' => $import->id,
                    'entity' => $payload['entity'],
                    'source_column' => $src,
                    'target_field' => $payload['target_field'],
                    'transform' => $payload['transform'],
                    'apply_mode' => $payload['apply_mode'],
                    'options' => $payload['options'],
                    'position' => ++$basePosition,
                    'created_at' => $now,
                    'updated_at' => $now,
                ]);
                $inserted++;
            }
        }

        // Mark this as ad-hoc mapping usage
        $import->update(['import_template_id' => null]);

        return response()->json(['ok' => true, 'saved' => ($inserted + $updated), 'inserted' => $inserted, 'updated' => $updated, 'deduped' => $deduped]);
    }

    // Fetch current mappings for an import (after applying a template or saving ad-hoc mappings)
    public function getMappings(Import $import)
    {
        $rows = \DB::table('import_mappings')
            ->where('import_id', $import->id)
            ->orderBy('position')
            ->orderBy('id')
            ->get([
                'id',
                'entity',
                'source_column',
                'target_field',
                'transform',
                'apply_mode',
                'options',
                'position',
            ]);

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

    /**
     * List active, non-archived contracts for the import's client that are NOT present
     * in the processed import file (based on mapped contract.reference values).
     * Only available when contract.reference mapping apply_mode is 'keyref'.
     */
    public function missingContracts(Import $import)
    {
        // Ensure client context is available
        if (empty($import->client_id)) {
            return response()->json(['error' => 'Import has no client bound.'], 422);
        }

        // Respect optional feature flag on import
        if (! (bool) ($import->show_missing ?? false)) {
            return response()->json(['error' => 'Missing contracts listing is disabled for this import.'], 422);
        }

        // Check that this import's mappings set contract.reference to keyref mode
        $mappings = \DB::table('import_mappings')
            ->where('import_id', $import->id)
            ->get(['target_field', 'apply_mode']);
        $isKeyref = false;
        foreach ($mappings as $map) {
            $tf = strtolower((string) ($map->target_field ?? ''));
            $am = strtolower((string) ($map->apply_mode ?? ''));
            if (in_array($tf, ['contract.reference', 'contracts.reference'], true) && $am === 'keyref') {
                $isKeyref = true;
                break;
            }
        }
        if (! $isKeyref) {
            return response()->json(['error' => 'Missing contracts are only available for keyref mapping on contract.reference.'], 422);
        }

        // Collect referenced contract references from processed rows
        $present = [];
        foreach (\App\Models\ImportRow::query()->where('import_id', $import->id)->get(['mapped_data']) as $row) {
            $md = $row->mapped_data ?? [];
            if (is_array($md) && isset($md['contract']['reference'])) {
                $ref = (string) $md['contract']['reference'];
                if ($ref !== '') {
                    $present[] = preg_replace('/\s+/', '', trim($ref));
                }
            }
        }
        $present = array_values(array_unique(array_filter($present)));

        // Query active, non-archived contracts for this client that were not in import
        // Include person full_name (owner of the client case) and aggregate active accounts' balance_amount
        $contractsQ = \App\Models\Contract::query()
            ->join('client_cases', 'contracts.client_case_id', '=', 'client_cases.id')
            ->join('person', 'person.id', '=', 'client_cases.person_id')
            ->leftJoin('accounts', function ($join) {
                $join->on('accounts.contract_id', '=', 'contracts.id')
                    ->where('accounts.active', 1);
            })
            ->where('client_cases.client_id', $import->client_id)
            ->where('contracts.active', 1)
            ->whereNull('contracts.deleted_at')
            ->when(count($present) > 0, function ($q) use ($present) {
                $q->whereNotIn('contracts.reference', $present);
            })
            ->groupBy('contracts.uuid', 'contracts.reference', 'client_cases.uuid', 'person.full_name')
            ->orderBy('contracts.reference')
            ->get([
                'contracts.uuid as uuid',
                'contracts.reference as reference',
                'client_cases.uuid as case_uuid',
                'person.full_name as full_name',
                \DB::raw('COALESCE(SUM(accounts.balance_amount), 0) as balance_amount'),
            ]);

        return response()->json([
            'missing' => $contractsQ,
            'count' => $contractsQ->count(),
        ]);
    }

    /**
     * Update import options (e.g., booleans like show_missing, reactivate) from the UI.
     */
    public function updateOptions(Request $request, Import $import)
    {
        $data = $request->validate([
            'show_missing' => 'nullable|boolean',
            'reactivate' => 'nullable|boolean',
        ]);

        $payload = [];
        if (array_key_exists('show_missing', $data)) {
            $payload['show_missing'] = (bool) $data['show_missing'];
        }
        if (array_key_exists('reactivate', $data)) {
            $payload['reactivate'] = (bool) $data['reactivate'];
        }
        if (! empty($payload)) {
            $import->update($payload);
        }

        return response()->json([
            'ok' => true,
            'import' => [
                'id' => $import->id,
                'uuid' => $import->uuid,
                'show_missing' => (bool) ($import->show_missing ?? false),
                'reactivate' => (bool) ($import->reactivate ?? false),
            ],
        ]);
    }

    // Fetch recent import events (logs) for an import
    public function getEvents(Import $import)
    {
        $limit = (int) request()->query('limit', 200);
        $limit = max(1, min($limit, 1000));
        $events = ImportEvent::query()
            ->where('import_id', $import->id)
            ->orderByDesc('id')
            ->limit($limit)
            ->get(['id', 'created_at', 'level', 'event', 'message', 'import_row_id', 'context']);

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

    // Preview (up to N) raw CSV rows for an import for mapping review
    public function preview(Import $import, Request $request)
    {
        $validated = $request->validate([
            'limit' => 'nullable|integer|min:1|max:500',
        ]);
        $limit = (int) ($validated['limit'] ?? 200);

        // Determine header/delimiter the same way as columns() stored them
        $meta = $import->meta ?? [];
        $hasHeader = (bool) ($meta['has_header'] ?? true);
        // Forced delimiter overrides everything; else detected; fallback comma
        $delimiter = $meta['forced_delimiter']
            ?? $meta['detected_delimiter']
            ?? ',';

        $rows = [];
        $columns = [];
        $truncated = false;
        $path = Storage::disk($import->disk)->path($import->path);
        if (! is_readable($path)) {
            return response()->json([
                'error' => 'File not readable',
            ], 422);
        }
        $fh = @fopen($path, 'r');
        if (! $fh) {
            return response()->json([
                'error' => 'Unable to open file',
            ], 422);
        }
        try {
            if ($hasHeader) {
                $header = fgetcsv($fh, 0, $delimiter) ?: [];
                $columns = array_map(function ($h) {
                    return is_string($h) ? trim($h) : (string) $h;
                }, $header);
            } else {
                // Use meta stored columns when available, else infer later from widest row
                $columns = is_array($meta['columns'] ?? null) ? $meta['columns'] : [];
            }
            $count = 0;
            $widest = count($columns);
            while (($data = fgetcsv($fh, 0, $delimiter)) !== false) {
                if ($count >= $limit) {
                    $truncated = true;
                    break;
                }
                // Track widest for non-header scenario
                if (! $hasHeader) {
                    $widest = max($widest, count($data));
                }
                $rows[] = $data;
                $count++;
            }
            if (! $hasHeader && $widest > count($columns)) {
                // Generate positional column labels if missing
                $columns = [];
                for ($i = 0; $i < $widest; $i++) {
                    $columns[] = 'col_'.($i + 1);
                }
            }
        } finally {
            fclose($fh);
        }

        // Normalize each row into assoc keyed by columns (pad/truncate as needed)
        $assocRows = [];
        foreach ($rows as $r) {
            $assoc = [];
            foreach ($columns as $i => $colName) {
                $assoc[$colName] = array_key_exists($i, $r) ? $r[$i] : null;
            }
            $assocRows[] = $assoc;
        }

        return response()->json([
            'columns' => $columns,
            'rows' => $assocRows,
            'limit' => $limit,
            'truncated' => $truncated,
            'has_header' => $hasHeader,
        ]);
    }

    /**
     * Simulate application of payment rows for a payments import without persisting changes.
     * Returns per-row projected balance changes and resolution of contract / account references.
     */
    public function simulatePayments(Import $import, Request $request)
    {
        // Delegate to the generic simulate method for backward compatibility.
        return $this->simulate($import, $request);
    }

    /**
     * Generic simulation endpoint: projects what would happen if the import were processed
     * using the first N rows and current saved mappings. Works for both payments and non-payments
     * templates. For payments templates, payment-specific summaries/entities will be included
     * automatically by the simulation service when mappings contain the payment root.
     */
    public function simulate(Import $import, Request $request)
    {
        $validated = $request->validate([
            'limit' => 'nullable|integer|min:1|max:500',
            'verbose' => 'nullable|boolean',
        ]);
        $limit = (int) ($validated['limit'] ?? 100);
        $verbose = (bool) ($validated['verbose'] ?? false);

        $service = app(\App\Services\ImportSimulationService::class);
        $result = $service->simulate($import, $limit, $verbose);

        return response()->json($result);
    }

    // Show an existing import by UUID to continue where left off
    public function show(Import $import)
    {
        // Load templates (global + client specific) and clients for selection on continue page
        $templates = ImportTemplate::query()
            ->leftJoin('clients', 'clients.id', '=', 'import_templates.client_id')
            ->where('import_templates.is_active', true)
            ->where('import_templates.id', $import->import_template_id)
            ->orderBy('import_templates.name')
            ->get([
                'import_templates.id',
                'import_templates.uuid',
                'import_templates.name',
                'import_templates.source_type',
                'import_templates.default_record_type',
                'import_templates.client_id',
                'import_templates.meta',
                'clients.uuid as client_uuid',
            ]);

        $clients = Client::query()
            ->join('person', 'person.id', '=', 'clients.person_id')
            ->orderBy('person.full_name')
            ->where('clients.id', $import->client_id)
            ->get([
                'clients.id',
                'clients.uuid',
                'person.full_name as name',
            ]);

        // Import client
        $client = Client::query()
            ->join('person', 'person.id', '=', 'clients.person_id')
            ->where('clients.id', $import->client_id)
            ->firstOrFail([
                'clients.uuid as uuid',
                'person.full_name as name',
            ]);

        // Render a dedicated page to continue the import
        return Inertia::render('Imports/Import', [
            'import' => [
                'id' => $import->id,
                'uuid' => $import->uuid,
                'status' => $import->status,
                'meta' => $import->meta,
                'client_id' => $import->client_id,
                'client_uuid' => optional($client)->uuid,
                'import_template_id' => $import->import_template_id,
                'show_missing' => (bool) ($import->show_missing ?? false),
                'reactivate' => (bool) ($import->reactivate ?? false),
                'total_rows' => $import->total_rows,
                'imported_rows' => $import->imported_rows,
                'invalid_rows' => $import->invalid_rows,
                'valid_rows' => $import->valid_rows,
                'finished_at' => $import->finished_at,
            ],
            'templates' => $templates,
            'clients' => $clients,
            'client' => $client,
        ]);
    }

    // Delete an import if not finished (statuses allowed: uploaded, mapping, processing_failed etc.)
    public function destroy(Request $request, Import $import)
    {
        // Only allow deletion if not completed or processing
        if (in_array($import->status, ['completed', 'processing'])) {
            return back()->with([
                'ok' => false,
                'message' => 'Import can not be deleted in its current status.',
            ], 422);
        }

        // Attempt to delete stored file
        try {
            if ($import->disk && $import->path && Storage::disk($import->disk)->exists($import->path)) {
                Storage::disk($import->disk)->delete($import->path);
            }
        } catch (\Throwable $e) {
            // Log event but proceed with deletion
            ImportEvent::create([
                'import_id' => $import->id,
                'user_id' => $request->user()?->getAuthIdentifier(),
                'event' => 'file_delete_failed',
                'level' => 'warning',
                'message' => 'Failed to delete import file: '.$e->getMessage(),
            ]);
        }

        // Clean up related events/rows optionally (soft approach: rely on FKs if cascade configured)
        // If not cascaded, we could manually delete; check quickly
        // Assuming foreign key ON DELETE CASCADE for import_rows & import_events

        $import->delete();

        return back()->with(['ok' => true]);
    }
}