<?php
declare(strict_types=1);

/**
 * DMS helpers: folder ACLs, storage paths, audit logging, version bookkeeping.
 * Loaded from bootstrap.php so all dashboard pages + APIs get them implicitly.
 */

const DBN_DMS_MAX_FOLDER_DEPTH    = 2;   // Matches ai-portal app-layer cap. Raise here to unlock deeper nesting.
const DBN_DMS_MAX_VERSIONS_PER_DOC = 20; // Oldest auto-pruned beyond this.
const DBN_DMS_TRASH_RETENTION_DAYS = 30;
const DBN_DMS_DEFAULT_CATEGORIES = [
    ['slug' => 'uncategorized', 'label' => 'Uncategorized', 'color' => '#94a3b8', 'icon' => 'folder',     'sort_order' =>  0],
    ['slug' => 'legal',         'label' => 'Legal',         'color' => '#1d4ed8', 'icon' => 'scale',      'sort_order' => 10],
    ['slug' => 'financial',     'label' => 'Financial',     'color' => '#047857', 'icon' => 'chart',      'sort_order' => 20],
    ['slug' => 'internal',      'label' => 'Internal',      'color' => '#7c3aed', 'icon' => 'building',   'sort_order' => 30],
    ['slug' => 'hr',            'label' => 'HR',            'color' => '#db2777', 'icon' => 'people',     'sort_order' => 40],
    ['slug' => 'marketing',     'label' => 'Marketing',     'color' => '#b88a2c', 'icon' => 'megaphone',  'sort_order' => 50],
];

/**
 * Resolve the on-disk storage path for an uploaded document.
 * Production: /home/dobetternorge/uploads/{client_id}/{document_id}.{ext}
 * Local dev:  DBN_TOOLS_UPLOAD_ROOT env override, else DBN_TOOLS_ROOT/uploads/...
 */
function dbnDmsStoragePath(int $clientId, int $documentId, string $ext, ?int $versionNumber = null): string
{
    $root = dbnToolsEnv('DBN_TOOLS_UPLOAD_ROOT', '');
    if ($root === '' || $root === null) {
        $root = is_dir('/home/dobetternorge/uploads')
            ? '/home/dobetternorge/uploads'
            : DBN_TOOLS_ROOT . '/uploads';
    }

    $ext = preg_replace('/[^a-z0-9]/', '', strtolower($ext)) ?: 'bin';
    $clientDir = rtrim($root, '/') . '/' . $clientId;
    if (!is_dir($clientDir)) {
        @mkdir($clientDir, 0750, true);
    }

    if ($versionNumber !== null && $versionNumber > 0) {
        $versionDir = $clientDir . '/' . $documentId . '_versions';
        if (!is_dir($versionDir)) {
            @mkdir($versionDir, 0750, true);
        }
        return $versionDir . '/v' . $versionNumber . '.' . $ext;
    }

    return $clientDir . '/' . $documentId . '.' . $ext;
}

/**
 * Stream an uploaded file into permanent storage. Returns the storage_path string,
 * or null if persistence is disabled (no upload root and not writable).
 */
function dbnDmsPersistFile(string $tmpPath, int $clientId, int $documentId, string $ext, ?int $versionNumber = null): ?string
{
    $dest = dbnDmsStoragePath($clientId, $documentId, $ext, $versionNumber);
    $dir  = dirname($dest);
    if (!is_dir($dir) || !is_writable($dir)) {
        return null;
    }
    if (!@copy($tmpPath, $dest)) {
        return null;
    }
    @chmod($dest, 0640);
    return $dest;
}

/**
 * Walk the folder tree starting at $folderId upward; returns the chain root→leaf.
 * Returns [] if $folderId is null/0 (root).
 */
function dbnDmsFolderChain(?int $folderId, int $clientId): array
{
    if (!$folderId) {
        return [];
    }
    $db = dbnToolsDb();
    $chain = [];
    $current = $folderId;
    $guard = 0;
    while ($current && $guard++ < 50) {
        $stmt = $db->prepare('SELECT id, name, parent_id, color FROM client_folders WHERE id = ? AND client_id = ? AND deleted_at IS NULL');
        $stmt->execute([$current, $clientId]);
        $row = $stmt->fetch();
        if (!$row) {
            break;
        }
        $chain[] = $row;
        $current = $row['parent_id'] ? (int)$row['parent_id'] : 0;
    }
    return array_reverse($chain);
}

/**
 * Resolve the breadcrumb for a folder as [{id, name}, …] starting at the root.
 * Returns [] when at corpus root.
 */
function dbnDmsBreadcrumb(?int $folderId, int $clientId): array
{
    return array_map(fn($r) => ['id' => (int)$r['id'], 'name' => (string)$r['name'], 'color' => $r['color'] ?? null],
        dbnDmsFolderChain($folderId, $clientId));
}

/**
 * Folder depth, where root-level = 1. Used to enforce DBN_DMS_MAX_FOLDER_DEPTH.
 */
function dbnDmsFolderDepth(?int $folderId, int $clientId): int
{
    if (!$folderId) {
        return 0;
    }
    return count(dbnDmsFolderChain($folderId, $clientId));
}

/**
 * Check whether the current user can act on $folderId with $perm = 'read'|'write'|'manage'.
 * Permission resolution:
 *   - tenant owner/admin role → always allowed
 *   - walk folder chain leaf→root; first matching ACL row wins
 *   - no ACL rows anywhere → open (default)
 */
function dbnDmsUserCanAccessFolder(?int $folderId, string $perm, int $clientId, int $userId, string $tenantRole = 'viewer'): bool
{
    // Tenant root is always readable; only manage requires editor+.
    if (!$folderId) {
        if ($perm === 'manage' || $perm === 'write') {
            return in_array($tenantRole, ['editor', 'admin', 'owner'], true);
        }
        return true;
    }
    if (in_array($tenantRole, ['admin', 'owner'], true)) {
        return true;
    }

    $db = dbnToolsDb();
    $chain = dbnDmsFolderChain($folderId, $clientId);
    if (!$chain) {
        return false;
    }

    $col = match ($perm) {
        'write'  => 'can_write',
        'manage' => 'can_manage',
        default  => 'can_read',
    };

    $anyAcl = false;
    foreach (array_reverse($chain) as $folder) {
        $stmt = $db->prepare(
            "SELECT min_role, user_id, can_read, can_write, can_manage
             FROM client_folder_permissions
             WHERE folder_id = ? AND client_id = ?"
        );
        $stmt->execute([(int)$folder['id'], $clientId]);
        $rows = $stmt->fetchAll();
        if (!$rows) {
            continue;
        }
        $anyAcl = true;

        foreach ($rows as $row) {
            if ($row['user_id'] !== null && (int)$row['user_id'] === $userId) {
                if ((int)$row[$col] === 1) return true;
            }
            if ($row['min_role'] !== null) {
                if (dbnDmsRoleAtLeast($tenantRole, (string)$row['min_role']) && (int)$row[$col] === 1) {
                    return true;
                }
            }
        }
        // ACL at this level but user not granted — block (no inheritance past explicit restriction).
        return false;
    }

    // No ACL rows anywhere → open per migration 119 convention.
    return !$anyAcl;
}

function dbnDmsRoleAtLeast(string $userRole, string $minRole): bool
{
    $rank = ['viewer' => 0, 'editor' => 1, 'admin' => 2, 'owner' => 3];
    return ($rank[$userRole] ?? 0) >= ($rank[$minRole] ?? 0);
}

/**
 * Append an audit row. Failure is swallowed — auditing must never break the request.
 */
function dbnDmsLogAudit(int $clientId, ?int $userId, string $action, array $details = [], ?int $documentId = null, ?int $folderId = null): void
{
    try {
        $db = dbnToolsDb();
        $stmt = $db->prepare(
            'INSERT INTO client_document_audit (client_id, user_id, document_id, folder_id, action, details, ip_addr, created_at)
             VALUES (?, ?, ?, ?, ?, ?, ?, NOW())'
        );
        $stmt->execute([
            $clientId,
            $userId ?: null,
            $documentId ?: null,
            $folderId ?: null,
            substr($action, 0, 40),
            $details ? json_encode($details, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES) : null,
            substr((string)($_SERVER['REMOTE_ADDR'] ?? ''), 0, 45),
        ]);
    } catch (Throwable $e) {
        error_log('[dbn-dms] audit insert failed: ' . $e->getMessage());
    }
}

/**
 * Seed default categories for a tenant if their dictionary is empty.
 * Idempotent — safe to call on every dashboard page load.
 */
function dbnDmsSeedDefaultCategoriesIfEmpty(int $clientId): void
{
    try {
        $db = dbnToolsDb();
        $check = $db->prepare('SELECT COUNT(*) FROM client_categories WHERE client_id = ?');
        $check->execute([$clientId]);
        if ((int)$check->fetchColumn() > 0) {
            return;
        }
        $ins = $db->prepare(
            'INSERT INTO client_categories (client_id, slug, label, color, icon, sort_order, is_system)
             VALUES (?, ?, ?, ?, ?, ?, 1)'
        );
        foreach (DBN_DMS_DEFAULT_CATEGORIES as $cat) {
            $ins->execute([
                $clientId,
                $cat['slug'],
                $cat['label'],
                $cat['color'],
                $cat['icon'],
                $cat['sort_order'],
            ]);
        }
    } catch (Throwable $e) {
        // Likely table doesn't exist yet (migration not applied).
        error_log('[dbn-dms] seed categories failed: ' . $e->getMessage());
    }
}

/**
 * Snapshot a document into client_document_versions before overwriting.
 * Returns the new version_number, or 0 on failure.
 */
function dbnDmsSnapshotVersion(int $documentId, int $clientId, ?int $userId, ?string $notes = null): int
{
    $db = dbnToolsDb();
    $doc = $db->prepare('SELECT * FROM client_documents WHERE id = ? AND client_id = ?');
    $doc->execute([$documentId, $clientId]);
    $row = $doc->fetch();
    if (!$row) {
        return 0;
    }

    $next = (int)($row['current_version'] ?? 1);

    $ins = $db->prepare(
        'INSERT INTO client_document_versions
            (document_id, client_id, version_number, title, content, file_size_bytes,
             original_filename, storage_path, word_count, uploaded_by, notes, created_at)
         VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, NOW())'
    );
    $ins->execute([
        $documentId,
        $clientId,
        $next,
        (string)$row['title'],
        (string)($row['content'] ?? ''),
        (int)($row['file_size_bytes'] ?? 0),
        $row['original_filename'] ?? null,
        $row['storage_path'] ?? null,
        (int)($row['word_count'] ?? 0),
        $userId ?: null,
        $notes,
    ]);

    // Prune oldest versions beyond cap.
    $count = $db->prepare('SELECT COUNT(*) FROM client_document_versions WHERE document_id = ?');
    $count->execute([$documentId]);
    $total = (int)$count->fetchColumn();
    if ($total > DBN_DMS_MAX_VERSIONS_PER_DOC) {
        $prune = $db->prepare(
            'DELETE FROM client_document_versions
             WHERE document_id = ?
             ORDER BY version_number ASC
             LIMIT ' . ($total - DBN_DMS_MAX_VERSIONS_PER_DOC)
        );
        $prune->execute([$documentId]);
    }

    return $next;
}

/**
 * Convenience: file extension from an upload array (original_filename) or filename string.
 */
function dbnDmsExtensionFromFilename(string $filename): string
{
    $dot = strrpos($filename, '.');
    if ($dot === false) {
        return '';
    }
    return strtolower(substr($filename, $dot + 1));
}

/**
 * Extract plain text from HTML (strip tags, decode entities).
 */
function dbnDmsExtractHtml(string $path): string
{
    $raw = file_get_contents($path);
    if ($raw === false) {
        throw new DbnToolsHttpException('Unable to read HTML file.', 500, 'read_error');
    }
    $raw = mb_convert_encoding($raw, 'UTF-8', 'UTF-8, ISO-8859-1, Windows-1252');
    $raw = preg_replace('#<script\b[^>]*>.*?</script>#is', '', $raw) ?? $raw;
    $raw = preg_replace('#<style\b[^>]*>.*?</style>#is', '', $raw) ?? $raw;
    $text = trim(html_entity_decode(strip_tags($raw), ENT_QUOTES | ENT_HTML5, 'UTF-8'));
    return preg_replace("/[\r\n]{3,}/", "\n\n", $text) ?? $text;
}

/**
 * Extract CSV as readable text (header row repeated each line for context).
 */
function dbnDmsExtractCsv(string $path): string
{
    $fh = @fopen($path, 'rb');
    if (!$fh) {
        throw new DbnToolsHttpException('Unable to read CSV file.', 500, 'read_error');
    }
    $lines  = [];
    $header = null;
    $rowNum = 0;
    while (($row = fgetcsv($fh, 0, ',', '"', '\\')) !== false) {
        $row = array_map(fn($c) => (string)$c, $row);
        if ($header === null) {
            $header = $row;
            $lines[] = implode(' | ', $header);
            continue;
        }
        $pairs = [];
        foreach ($row as $i => $cell) {
            $col = $header[$i] ?? "col{$i}";
            if ($cell !== '') {
                $pairs[] = $col . ': ' . $cell;
            }
        }
        $lines[] = '- ' . implode('; ', $pairs);
        if (++$rowNum > 5000) {
            $lines[] = '... (truncated)';
            break;
        }
    }
    fclose($fh);
    return implode("\n", $lines);
}

/**
 * Extract plain text from XLSX (concatenate sharedStrings + cell values).
 * Lightweight — no PhpSpreadsheet dependency.
 */
function dbnDmsExtractXlsx(string $path): string
{
    $zip = new ZipArchive();
    if ($zip->open($path) !== true) {
        throw new DbnToolsHttpException('Unable to open XLSX file.', 422, 'xlsx_open_failed');
    }
    $shared = [];
    $sharedXml = $zip->getFromName('xl/sharedStrings.xml');
    if ($sharedXml !== false) {
        if (preg_match_all('#<t[^>]*>(.*?)</t>#s', $sharedXml, $m)) {
            foreach ($m[1] as $s) {
                $shared[] = html_entity_decode(strip_tags($s), ENT_QUOTES | ENT_XML1, 'UTF-8');
            }
        }
    }
    $out = [];
    for ($i = 1; $i < 100; $i++) {
        $sheet = $zip->getFromName("xl/worksheets/sheet{$i}.xml");
        if ($sheet === false) break;
        // Inline strings + numeric/text values.
        if (preg_match_all('#<c\b[^>]*?(?:\s+t="([^"]*)")?[^>]*>(.*?)</c>#s', $sheet, $m, PREG_SET_ORDER)) {
            $cells = [];
            foreach ($m as $cell) {
                $type = $cell[1] ?? '';
                $inner = $cell[2];
                if ($type === 's') {
                    if (preg_match('#<v>(\d+)</v>#', $inner, $vm)) {
                        $idx = (int)$vm[1];
                        if (isset($shared[$idx])) $cells[] = $shared[$idx];
                    }
                } elseif ($type === 'inlineStr') {
                    if (preg_match('#<t[^>]*>(.*?)</t>#s', $inner, $tm)) {
                        $cells[] = html_entity_decode(strip_tags($tm[1]), ENT_QUOTES | ENT_XML1, 'UTF-8');
                    }
                } else {
                    if (preg_match('#<v>(.*?)</v>#', $inner, $vm)) {
                        $cells[] = $vm[1];
                    }
                }
            }
            $out[] = "=== Sheet {$i} ===\n" . implode("\t", $cells);
        }
    }
    $zip->close();
    $text = implode("\n\n", $out);
    if (trim($text) === '') {
        throw new DbnToolsHttpException('No readable content in XLSX.', 422, 'xlsx_empty');
    }
    return $text;
}

/**
 * Extract plain text from PPTX (slide notes + text frames).
 */
function dbnDmsExtractPptx(string $path): string
{
    $zip = new ZipArchive();
    if ($zip->open($path) !== true) {
        throw new DbnToolsHttpException('Unable to open PPTX file.', 422, 'pptx_open_failed');
    }
    $slides = [];
    for ($i = 1; $i < 500; $i++) {
        $xml = $zip->getFromName("ppt/slides/slide{$i}.xml");
        if ($xml === false) break;
        $text = [];
        if (preg_match_all('#<a:t[^>]*>(.*?)</a:t>#s', $xml, $m)) {
            foreach ($m[1] as $t) {
                $text[] = html_entity_decode(strip_tags($t), ENT_QUOTES | ENT_XML1, 'UTF-8');
            }
        }
        if ($text) {
            $slides[] = "=== Slide {$i} ===\n" . implode("\n", $text);
        }
    }
    $zip->close();
    if (!$slides) {
        throw new DbnToolsHttpException('No readable content in PPTX.', 422, 'pptx_empty');
    }
    return implode("\n\n", $slides);
}

/**
 * Convenience: MIME type → safe content type for inline preview/download streaming.
 */
function dbnDmsContentTypeForExt(string $ext): string
{
    return match (strtolower($ext)) {
        'pdf'  => 'application/pdf',
        'docx' => 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
        'xlsx' => 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
        'pptx' => 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
        'txt'  => 'text/plain; charset=utf-8',
        'md'   => 'text/markdown; charset=utf-8',
        'csv'  => 'text/csv; charset=utf-8',
        'html', 'htm' => 'text/html; charset=utf-8',
        'json' => 'application/json',
        'mp3'  => 'audio/mpeg',
        'wav'  => 'audio/wav',
        'm4a'  => 'audio/mp4',
        'ogg'  => 'audio/ogg',
        'png'  => 'image/png',
        'jpg', 'jpeg' => 'image/jpeg',
        'webp' => 'image/webp',
        default => 'application/octet-stream',
    };
}