/**
 * Directory Scanner Module
 * Scans directories and collects files
 */
(function() {
    'use strict';
    
    // Store ZIP data for later access
    const zipCache = new Map();  // path -> { zip: JSZip, fileHandle: FileSystemFileHandle }

    // ── Incremental-scan state ───────────────────────────────────────────────
    // The scan no longer reads the whole tree before rendering. It walks
    // breadth-first behind a small worker pool, renders progressively (top
    // levels appear first), and shows live status — so a huge network drive
    // never looks stalled. Each folder tracks its own scan state + counts.
    let scanGen = 0;                 // bumped per scan; stale workers bail
    let scanStats = null;            // { folders, files, current, done, startedAt }
    let renderTimer = null;          // throttle for progressive re-render

    function scheduleRender() {
        if (renderTimer) return;
        renderTimer = setTimeout(function () {
            renderTimer = null;
            try { window.app.modules.tree.render(); } catch (_) { /* ignore */ }
            updateScanStatus();
        }, 180);
    }

    function flushRender() {
        if (renderTimer) { clearTimeout(renderTimer); renderTimer = null; }
        try { window.app.modules.tree.render(); } catch (_) { /* ignore */ }
        updateScanStatus();
    }

    // Render the running scan status into the tree-pane header.
    function updateScanStatus() {
        const el = document.getElementById('scanStatus');
        if (!el || !scanStats) return;
        if (scanStats.done) {
            const secs = ((Date.now() - scanStats.startedAt) / 1000).toFixed(1);
            el.textContent = 'Scanned ' + scanStats.folders + ' folders · '
                + scanStats.files + ' files in ' + secs + 's';
            el.classList.remove('scanning');
        } else {
            el.textContent = 'Scanning… ' + scanStats.folders + ' folders · '
                + scanStats.files + ' files'
                + (scanStats.current ? ' — ' + scanStats.current : '');
            el.classList.add('scanning');
        }
    }

    // Make a tree node. scanState: 'pending' (children not read) →
    // 'scanning' → 'children' (immediate children read, subtree still going) →
    // 'done' (entire subtree enumerated). The UI greys a node until 'done'.
    function makeNode(handle, path, parent) {
        const node = {
            name: handle.name,
            path: path,
            handle: handle,
            parent: parent || null,
            files: [],
            fileCount: 0,              // direct files in this folder
            subdirCount: 0,            // direct subfolders
            runFiles: 0,               // files in the whole subtree (grows as scanned; final on 'done')
            runDirs: 0,                // subfolders in the whole subtree
            children: [],
            expanded: false,
            scanState: 'pending',
            pending: 0,                // child dirs not yet 'done'
        };
        if (handle.isZipRoot) { node.isZipRoot = true; node.zipPath = handle.zipPath; }
        if (handle.isVirtualDir) { node.isVirtualDir = true; node.zipPath = handle.zipPath; }
        return node;
    }

    // Mark a node's subtree fully scanned: roll up recursive totals and
    // propagate completion to the parent (which flips to 'done' once all its
    // children are done). This is what turns a folder from grey to solid.
    function markDone(node) {
        if (node.scanState === 'done') return;
        // runFiles/runDirs were accumulated into this node (and its ancestors)
        // as each descendant was scanned, so by the time the subtree is
        // complete they already hold the final totals — nothing to compute.
        node.scanState = 'done';
        const p = node.parent;
        if (p && p.scanState !== 'done') {
            p.pending -= 1;
            if (p.pending <= 0 && (p.scanState === 'children' || p.scanState === 'scanning')) {
                markDone(p);
            }
        }
    }

    // One-shot toast for scan errors (permission denied, network hiccups on a
    // share). De-duped per path so a flaky folder doesn't spam.
    const scanErrorsSeen = new Set();
    function reportScanError(path, err) {
        console.error('Scan error:', path, err);
        if (scanErrorsSeen.has(path)) return;
        scanErrorsSeen.add(path);
        const msg = 'Couldn’t scan ' + path + ': ' + (err && err.message ? err.message : err);
        if (window.zddc && typeof window.zddc.toast === 'function') {
            window.zddc.toast(msg, 'error');
        }
    }

    /**
     * Scan directory and build folder tree with files
     */
    async function scanDirectory(dirHandle, preserveState = false) {
        // Preserve which folders were expanded across a rescan (e.g. after a
        // ZIP extract) so the user doesn't lose their place.
        let savedExpanded = new Set();
        let savedSelected = new Set();
        if (preserveState) {
            savedExpanded = getExpandedPaths(window.app.folderTree);
            savedSelected = new Set(window.app.selectedFolders);
        }

        const myGen = ++scanGen;
        zipCache.clear();
        scanStats = { folders: 0, files: 0, current: dirHandle.name, done: false, startedAt: Date.now() };

        // Root node — render immediately so the pane never sits blank.
        const root = makeNode(dirHandle, dirHandle.name, null);
        root.expanded = true;
        window.app.folderTree = [root];
        window.app.modules.store.setFolderTree(window.app.folderTree);
        if (!preserveState) {
            // Select the root so the grid shows its immediate files at once,
            // instead of auto-loading the ENTIRE drive (the old behaviour,
            // which is exactly what stalled on a large share).
            window.app.selectedFolders = new Set([root.path]);
            window.app.lastSelectedFolderPath = root.path;
            window.app.modules.store.setSelectedFolders(window.app.selectedFolders);
        } else {
            window.app.selectedFolders = savedSelected;
            window.app.modules.store.setSelectedFolders(savedSelected);
        }
        flushRender();

        // Breadth-first by level behind a bounded worker pool: level 1, then
        // level 2, … each rendered as it lands (top levels appear first).
        // Deeper levels keep filling in; workers await between directories so
        // the UI stays responsive on a slow/large network drive.
        let level = [root];
        while (level.length && myGen === scanGen) {
            await runWithConcurrency(level, 6, function (n) { return scanNodeChildren(n, myGen); });
            const next = [];
            for (const n of level) {
                for (const c of n.children) {
                    if (preserveState && savedExpanded.has(c.path)) c.expanded = true;
                    if (c.scanState === 'pending') next.push(c);
                }
            }
            level = next;
        }
        if (myGen !== scanGen) return; // superseded by a newer scan

        scanStats.done = true;
        scanStats.current = '';
        flushRender();
    }

    // Run fn over items with at most `limit` concurrent calls; resolves when
    // all have settled. Termination is clean (no transient-empty-queue race).
    async function runWithConcurrency(items, limit, fn) {
        let i = 0;
        async function runner() {
            while (i < items.length) {
                const idx = i++;
                await fn(items[idx]);
            }
        }
        const runners = [];
        for (let k = 0; k < Math.min(limit, items.length); k++) runners.push(runner());
        await Promise.all(runners);
    }

    // Force a folder's subtree to scan NOW (jumped ahead of the background
    // walk). Called when the user opens a folder, so an opened folder always
    // shows complete contents. Idempotent + shares the live scan generation.
    async function ensureScanned(node) {
        if (!node || !node.handle || node.scanState === 'done') return;
        const myGen = scanGen;
        let level = [node];
        while (level.length && myGen === scanGen) {
            await runWithConcurrency(level, 6, function (n) { return scanNodeChildren(n, myGen); });
            const next = [];
            for (const n of level) {
                for (const c of n.children) if (c.scanState === 'pending') next.push(c);
            }
            level = next;
        }
        flushRender();
    }
    
    /**
     * Get all expanded folder paths from tree
     */
    function getExpandedPaths(folders, paths = new Set()) {
        for (const folder of folders) {
            if (folder.expanded) {
                paths.add(folder.path);
            }
            if (folder.children) {
                getExpandedPaths(folder.children, paths);
            }
        }
        return paths;
    }
    
    /**
     * Restore expanded state to tree
     */
    function restoreExpandedPaths(folders, expandedPaths) {
        for (const folder of folders) {
            folder.expanded = expandedPaths.has(folder.path);
            if (folder.children) {
                restoreExpandedPaths(folder.children, expandedPaths);
            }
        }
    }

    // Read ONE directory's immediate entries: files into node.files, child
    // directories into node.children (left 'pending' for the BFS to descend).
    // A .zip becomes an expandable zip-root child, scanned inline (its
    // contents are already in memory once the entry is read). Idempotent:
    // only a 'pending' node is scanned, so concurrent callers (background +
    // open-prioritised) don't double-scan.
    async function scanNodeChildren(node, myGen) {
        if (node.scanState !== 'pending') return;
        node.scanState = 'scanning';
        if (scanStats) scanStats.current = node.path;
        const files = [];
        const childDirs = [];
        try {
            for await (const entry of node.handle.values()) {
                if (myGen !== scanGen) { node.scanState = 'pending'; return; } // cancelled
                if (entry.kind === 'file') {
                    const fo = await createFileObject(entry, node.handle);
                    if (!fo) continue;
                    fo.folderPath = node.path;
                    files.push(fo);
                    if (scanStats) scanStats.files++;
                    if (fo.extension === 'zip' && typeof JSZip !== 'undefined') {
                        const zipName = zddc.joinExtension(fo.originalFilename, fo.extension);
                        const zipPath = node.path + '/' + zipName;
                        const zh = { name: zipName, kind: 'directory', isZipRoot: true, zipPath: zipPath };
                        const zipNode = makeNode(zh, zipPath, node);
                        try { await scanZipIntoNode(zipNode, fo); }
                        catch (e) { reportScanError(zipPath, e); zipNode.scanState = 'done'; }
                        childDirs.push(zipNode);
                        if (scanStats) scanStats.folders++;
                    }
                } else if (entry.kind === 'directory') {
                    const childPath = node.path + '/' + entry.name;
                    childDirs.push(makeNode(entry, childPath, node));
                    if (scanStats) scanStats.folders++;
                }
            }
        } catch (err) {
            node.scanError = true;
            reportScanError(node.path, err);
        }
        node.files = files;
        node.fileCount = files.length;
        node.children = childDirs;
        node.subdirCount = childDirs.length;
        // Roll this folder's own files/dirs (plus the full contents of any
        // inline-zip children) into the running subtree totals of this node
        // and every ancestor. Regular child dirs add their own share when they
        // get scanned — that's how the total fills in progressively.
        let addF = files.length;
        let addD = childDirs.length;
        for (const c of childDirs) {
            if (c.scanState === 'done') { addF += c.runFiles; addD += c.runDirs; }
        }
        for (let a = node; a; a = a.parent) { a.runFiles += addF; a.runDirs += addD; }
        // Zip children are scanned inline ('done'); real dirs are still pending.
        node.pending = childDirs.filter(function (c) { return c.scanState !== 'done'; }).length;
        if (node.pending === 0) {
            markDone(node);
        } else {
            node.scanState = 'children';
        }
        scheduleRender();
    }

    // Build a zip-root node's children from its archive contents (in memory),
    // marking the whole zip subtree 'done' immediately. Mirrors the on-disk
    // node shape so the rest of the app treats zip folders like real ones.
    async function scanZipIntoNode(zipNode, fileObj) {
        const f = await fileObj.handle.getFile();
        const zip = await JSZip.loadAsync(await f.arrayBuffer());
        const zipPath = zipNode.path;
        zipCache.set(zipPath, { zip: zip, fileHandle: fileObj.handle, folderHandle: fileObj.folderHandle });
        const dirNodes = new Map();
        dirNodes.set(zipPath, zipNode);
        function ensureDir(dirPath) {
            if (dirNodes.has(dirPath)) return dirNodes.get(dirPath);
            const parentPath = dirPath.substring(0, dirPath.lastIndexOf('/'));
            const parent = ensureDir(parentPath);
            const name = dirPath.substring(dirPath.lastIndexOf('/') + 1);
            const vh = { name: name, kind: 'directory', isVirtualDir: true, zipPath: zipPath, virtualPath: dirPath };
            const child = makeNode(vh, dirPath, parent);
            parent.children.push(child);
            dirNodes.set(dirPath, child);
            return child;
        }
        zip.forEach(function (relativePath, entry) {
            if (entry.dir) {
                ensureDir(zipPath + '/' + relativePath.replace(/\/$/, ''));
            } else {
                const fileName = relativePath.split('/').pop();
                const fileDir = relativePath.includes('/')
                    ? zipPath + '/' + relativePath.substring(0, relativePath.lastIndexOf('/'))
                    : zipPath;
                const dirNode = ensureDir(fileDir);
                const split = zddc.splitExtension(fileName);
                dirNode.files.push({
                    originalFilename: split.name,
                    extension: split.extension,
                    size: entry._data ? entry._data.uncompressedSize : 0,
                    lastModified: entry.date ? entry.date.getTime() : Date.now(),
                    isVirtual: true,
                    zipPath: zipPath,
                    zipEntryPath: relativePath,
                    folderPath: dirNode.path,
                    trackingNumber: '', revision: '', status: '', title: '',
                    isDirty: false, error: false, errorMessage: '', validation: null, sha256: null
                });
            }
        });
        finalizeZipNode(zipNode);
    }

    // Roll up a zip node's counts + mark its whole subtree 'done'.
    function finalizeZipNode(node) {
        node.fileCount = node.files.length;
        node.subdirCount = node.children.length;
        let rf = node.files.length, rd = node.children.length;
        for (const c of node.children) { finalizeZipNode(c); rf += c.runFiles; rd += c.runDirs; }
        node.runFiles = rf;
        node.runDirs = rd;
        node.scanState = 'done';
        node.pending = 0;
    }
    
    /**
     * Scan a ZIP file and add its contents as virtual folders
     */
    async function scanZipFile(zipFileObj, foldersMap, parentPath, parentItems) {
        try {
            const fileObj = await zipFileObj.handle.getFile();
            const arrayBuffer = await fileObj.arrayBuffer();
            const zip = await JSZip.loadAsync(arrayBuffer);
            
            const zipPath = parentPath + '/' + zddc.joinExtension(zipFileObj.originalFilename, zipFileObj.extension);
            
            // Cache the ZIP for later extraction
            zipCache.set(zipPath, {
                zip: zip,
                fileHandle: zipFileObj.handle,
                folderHandle: zipFileObj.folderHandle
            });
            
            // Mark the file as a ZIP container
            zipFileObj.isZipContainer = true;
            zipFileObj.zipPath = zipPath;
            
            // Build virtual folder structure from ZIP contents
            const virtualFolders = new Map();  // path -> { files: [], subdirs: Set }
            virtualFolders.set(zipPath, { files: [], subdirs: new Set() });
            
            zip.forEach((relativePath, zipEntry) => {
                if (zipEntry.dir) {
                    // It's a directory
                    const dirPath = zipPath + '/' + relativePath.replace(/\/$/, '');
                    if (!virtualFolders.has(dirPath)) {
                        virtualFolders.set(dirPath, { files: [], subdirs: new Set() });
                    }
                    // Add to parent's subdirs
                    const parentDir = dirPath.substring(0, dirPath.lastIndexOf('/'));
                    if (virtualFolders.has(parentDir)) {
                        virtualFolders.get(parentDir).subdirs.add(dirPath);
                    }
                } else {
                    // It's a file
                    const fileName = relativePath.split('/').pop();
                    const fileDir = relativePath.includes('/') 
                        ? zipPath + '/' + relativePath.substring(0, relativePath.lastIndexOf('/'))
                        : zipPath;
                    
                    // Ensure parent directories exist
                    ensureVirtualPath(virtualFolders, zipPath, fileDir);
                    
                    // Create virtual file object
                    const split = zddc.splitExtension(fileName);

                    const virtualFile = {
                        originalFilename: split.name,
                        extension: split.extension,
                        size: zipEntry._data ? zipEntry._data.uncompressedSize : 0,
                        lastModified: zipEntry.date ? zipEntry.date.getTime() : Date.now(),
                        
                        // Virtual file markers
                        isVirtual: true,
                        zipPath: zipPath,
                        zipEntryPath: relativePath,
                        
                        // Editable fields
                        trackingNumber: '',
                        revision: '',
                        status: '',
                        title: '',
                        
                        // State
                        isDirty: false,
                        error: false,
                        errorMessage: '',
                        validation: null,
                        sha256: null
                    };
                    
                    virtualFolders.get(fileDir).files.push(virtualFile);
                }
            });
            
            // Convert virtual folders to format compatible with tree builder
            // Create a virtual handle for the ZIP root
            const zipVirtualHandle = {
                name: zddc.joinExtension(zipFileObj.originalFilename, zipFileObj.extension),
                kind: 'directory',
                isZipRoot: true,
                zipPath: zipPath
            };
            
            // Store virtual folder data
            buildVirtualFolderMap(virtualFolders, zipPath, foldersMap, zipVirtualHandle);
            
            // Add ZIP as a virtual directory in parent
            parentItems.push({
                handle: zipVirtualHandle,
                isDirectory: true,
                isZipRoot: true
            });
            
        } catch (err) {
            console.error('Error scanning ZIP file:', zipFileObj.originalFilename, err);
        }
    }
    
    /**
     * Ensure all parent directories exist in virtual folder map
     */
    function ensureVirtualPath(virtualFolders, zipPath, targetPath) {
        if (virtualFolders.has(targetPath)) return;
        
        const parts = targetPath.substring(zipPath.length + 1).split('/').filter(p => p);
        let currentPath = zipPath;
        
        for (const part of parts) {
            const parentPath = currentPath;
            currentPath = currentPath + '/' + part;
            
            if (!virtualFolders.has(currentPath)) {
                virtualFolders.set(currentPath, { files: [], subdirs: new Set() });
            }
            
            if (virtualFolders.has(parentPath)) {
                virtualFolders.get(parentPath).subdirs.add(currentPath);
            }
        }
    }
    
    /**
     * Build virtual folder entries for the foldersMap
     * Uses path strings as keys for virtual folders to avoid object reference issues
     */
    function buildVirtualFolderMap(virtualFolders, zipPath, foldersMap, zipVirtualHandle) {
        const rootData = virtualFolders.get(zipPath);
        if (!rootData) return;
        
        // Create items array for ZIP root
        const rootItems = [...rootData.files];
        
        // Add subdirectories
        for (const subdirPath of rootData.subdirs) {
            const subdirName = subdirPath.split('/').pop();
            const subdirHandle = {
                name: subdirName,
                kind: 'directory',
                isVirtualDir: true,
                virtualPath: subdirPath,
                zipPath: zipPath
            };
            rootItems.push({
                handle: subdirHandle,
                isDirectory: true,
                isVirtualDir: true
            });
            
            // Recursively add subdir contents
            buildVirtualSubfolder(virtualFolders, subdirPath, foldersMap, zipPath);
        }
        
        // Store with both the handle object AND the path string as keys
        // This ensures lookup works regardless of which reference is used
        foldersMap.set(zipVirtualHandle, rootItems);
        foldersMap.set(zipPath, rootItems);  // Path-based key for tree building
    }
    
    /**
     * Recursively build virtual subfolder entries
     */
    function buildVirtualSubfolder(virtualFolders, folderPath, foldersMap, zipPath) {
        const folderData = virtualFolders.get(folderPath);
        if (!folderData) return;
        
        const folderName = folderPath.split('/').pop();
        const folderHandle = {
            name: folderName,
            kind: 'directory',
            isVirtualDir: true,
            virtualPath: folderPath,
            zipPath: zipPath
        };
        
        const items = [...folderData.files];
        
        // Store with path string key for tree building lookup
        foldersMap.set(folderPath, items);
        
        // Add subdirectories
        for (const subdirPath of folderData.subdirs) {
            const subdirName = subdirPath.split('/').pop();
            const subdirHandle = {
                name: subdirName,
                kind: 'directory',
                isVirtualDir: true,
                virtualPath: subdirPath,
                zipPath: zipPath
            };
            items.push({
                handle: subdirHandle,
                isDirectory: true,
                isVirtualDir: true
            });
            
            // Recursively add subdir contents
            buildVirtualSubfolder(virtualFolders, subdirPath, foldersMap, zipPath);
        }
        
        foldersMap.set(folderHandle, items);
    }
    
    /**
     * Get cached ZIP data
     */
    function getZipCache(zipPath) {
        return zipCache.get(zipPath);
    }
    
    /**
     * Extract a ZIP file to its parent directory
     */
    async function extractZip(zipPath) {
        const cached = zipCache.get(zipPath);
        if (!cached) {
            throw new Error('ZIP not found in cache');
        }
        
        const { zip, folderHandle } = cached;
        
        // Get the ZIP filename without extension for the extract folder name
        const zipName = zipPath.split('/').pop();
        const extractFolderName = zipName.replace(/\.zip$/i, '');
        
        // Create extraction folder
        const extractFolder = await folderHandle.getDirectoryHandle(extractFolderName, { create: true });
        
        // Extract all files
        const entries = [];
        zip.forEach((relativePath, zipEntry) => {
            if (!zipEntry.dir) {
                entries.push({ path: relativePath, entry: zipEntry });
            }
        });
        
        for (const { path, entry } of entries) {
            try {
                // Create subdirectories if needed
                const parts = path.split('/');
                const fileName = parts.pop();
                
                let currentDir = extractFolder;
                for (const part of parts) {
                    if (part) {
                        currentDir = await currentDir.getDirectoryHandle(part, { create: true });
                    }
                }
                
                // Write file
                const content = await entry.async('arraybuffer');
                const fileHandle = await currentDir.getFileHandle(fileName, { create: true });
                const writable = await fileHandle.createWritable();
                await writable.write(content);
                await writable.close();
            } catch (err) {
                console.error('Error extracting file:', path, err);
            }
        }
        
        return extractFolderName;
    }

    /**
     * Create file object with metadata
     */
    async function createFileObject(fileHandle, folderHandle) {
        try {
            const file = await fileHandle.getFile();
            const split = zddc.splitExtension(file.name);

            return {
                handle: fileHandle,
                folderHandle: folderHandle,
                originalFilename: split.name,
                extension: split.extension,
                size: file.size,
                lastModified: file.lastModified,
                
                // Editable fields
                trackingNumber: '',
                revision: '',
                status: '',
                title: '',
                
                // State
                isDirty: false,
                error: false,
                errorMessage: '',
                validation: null,
                sha256: null
                // folderPath will be added later in buildTree
            };
        } catch (err) {
            console.error('Error reading file:', fileHandle.name, err);
            return null;
        }
    }

    // Export module
    window.app.modules.scanner = {
        scanDirectory,
        ensureScanned,
        getZipCache,
        extractZip
    };
})();