<?php

namespace App\Http\Controllers\Admin;

use App\Http\Controllers\Controller;
use App\Models\DocumentAccess;
use Carbon\Carbon;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;
use Inertia\Inertia;
use Inertia\Response;
use Symfony\Component\HttpFoundation\StreamedResponse;

class DocumentAccessController extends Controller
{
    /**
     * The date real client IPs started being recorded. Before this, the nginx
     * log stored only the docker gateway address, so unique-visitor counts are
     * not available for earlier periods and must not be implied.
     */
    private const IP_DATA_STARTS = '2026-07-30';

    /**
     * Per-document access counts over a selectable date range.
     */
    public function index(Request $request): Response
    {
        $validated = $request->validate([
            'from' => ['nullable', 'date'],
            'to' => ['nullable', 'date'],
            'include_bots' => ['nullable', 'boolean'],
        ]);

        $from = isset($validated['from'])
            ? Carbon::parse($validated['from'])->startOfDay()
            : Carbon::now()->subDays(60)->startOfDay();

        $to = isset($validated['to'])
            ? Carbon::parse($validated['to'])->endOfDay()
            : Carbon::now()->endOfDay();

        $includeBots = (bool) ($validated['include_bots'] ?? false);

        $documents = $this->documentCounts($from, $to, $includeBots);

        return Inertia::render('Admin/DocumentAccess', [
            'documents' => $documents,
            'daily' => $this->dailyCounts($from, $to, $includeBots),
            'filters' => [
                'from' => $from->toDateString(),
                'to' => $to->toDateString(),
                'include_bots' => $includeBots,
            ],
            'totals' => [
                'downloads' => $documents->sum('downloads'),
                'documents_touched' => $documents->count(),
                // Distinct across the whole range, not the sum of the per-document
                // column: one person pulling five documents is one visitor.
                'unique_visitors' => $this->uniqueVisitors($from, $to, $includeBots),
            ],
            // Drives the caveat shown in the UI.
            'ip_data_starts' => self::IP_DATA_STARTS,
            'range_predates_ip_data' => $from->lt(Carbon::parse(self::IP_DATA_STARTS)),
        ]);
    }

    /**
     * Export the current view as CSV, so figures can be cited or filed
     * without retyping them.
     */
    public function export(Request $request): StreamedResponse
    {
        $validated = $request->validate([
            'from' => ['nullable', 'date'],
            'to' => ['nullable', 'date'],
            'include_bots' => ['nullable', 'boolean'],
        ]);

        $from = isset($validated['from'])
            ? Carbon::parse($validated['from'])->startOfDay()
            : Carbon::now()->subDays(60)->startOfDay();

        $to = isset($validated['to'])
            ? Carbon::parse($validated['to'])->endOfDay()
            : Carbon::now()->endOfDay();

        $includeBots = (bool) ($validated['include_bots'] ?? false);
        $documents = $this->documentCounts($from, $to, $includeBots);
        $ipDataStarts = Carbon::parse(self::IP_DATA_STARTS);

        $filename = sprintf(
            'document-access-%s-to-%s.csv',
            $from->toDateString(),
            $to->toDateString()
        );

        return response()->streamDownload(function () use ($documents, $from, $ipDataStarts) {
            $out = fopen('php://output', 'w');

            fputcsv($out, ['Document', 'Downloads', 'Unique visitors', 'Last accessed']);

            foreach ($documents as $row) {
                fputcsv($out, [
                    $row['title'],
                    $row['downloads'],
                    // Blank rather than 0 where the figure is unknowable, so the
                    // spreadsheet cannot be read as "nobody downloaded this".
                    $row['unique_visitors'] === 0 ? '' : $row['unique_visitors'],
                    $row['last_accessed'],
                ]);
            }

            if ($from->lt($ipDataStarts)) {
                fputcsv($out, []);
                fputcsv($out, [
                    'Note: visitor IP addresses were only recorded from '
                    .$ipDataStarts->toDateString()
                    .'. Unique visitors are blank for earlier periods.',
                ]);
            }

            fclose($out);
        }, $filename, ['Content-Type' => 'text/csv']);
    }

    /**
     * Distinct visitors across the range as a whole.
     */
    private function uniqueVisitors(Carbon $from, Carbon $to, bool $includeBots): int
    {
        $query = DocumentAccess::query()
            ->whereBetween('accessed_at', [$from, $to])
            ->whereNotNull('ip_address');

        if (! $includeBots) {
            $query->excludingBots();
        }

        return (int) $query->distinct()->count('ip_address');
    }

    /**
     * Download counts per document, plus unique visitors where the underlying
     * rows actually carry an IP.
     */
    private function documentCounts(Carbon $from, Carbon $to, bool $includeBots)
    {
        $query = DocumentAccess::query()
            ->join('documents', 'documents.id', '=', 'document_accesses.document_id')
            ->whereBetween('document_accesses.accessed_at', [$from, $to]);

        if (! $includeBots) {
            $query->excludingBots();
        }

        return $query
            ->groupBy('documents.id', 'documents.title')
            ->orderByDesc('downloads')
            ->get([
                'documents.id',
                'documents.title',
                DB::raw('count(*) as downloads'),
                DB::raw('count(distinct document_accesses.ip_address) as unique_visitors'),
                DB::raw('max(document_accesses.accessed_at) as last_accessed'),
            ])
            ->map(fn ($row) => [
                'id' => $row->id,
                'title' => $row->title,
                'downloads' => (int) $row->downloads,
                'unique_visitors' => (int) $row->unique_visitors,
                'last_accessed' => Carbon::parse($row->last_accessed)->format('m/d/Y'),
            ]);
    }

    /**
     * Downloads per day, for the trend chart.
     */
    private function dailyCounts(Carbon $from, Carbon $to, bool $includeBots)
    {
        $query = DocumentAccess::query()
            ->whereBetween('accessed_at', [$from, $to]);

        if (! $includeBots) {
            $query->excludingBots();
        }

        return $query
            ->groupBy('day')
            ->orderBy('day')
            ->get([
                DB::raw('date(accessed_at) as day'),
                DB::raw('count(*) as downloads'),
            ])
            ->map(fn ($row) => [
                'day' => Carbon::parse($row->day)->format('m/d'),
                'downloads' => (int) $row->downloads,
            ]);
    }
}