import { NextRequest, NextResponse } from 'next/server'
import fs from 'fs'
import path from 'path'
import { writeFile, mkdir, unlink, readdir, stat } from 'fs/promises'

// Use /data for Hugging Face Spaces persistent storage, fallback to public/data for local dev
const DATA_DIR = process.env.SPACE_ID
    ? '/data'
    : path.join(process.cwd(), 'public', 'data')

// Ensure data directory exists
if (!fs.existsSync(DATA_DIR)) {
    fs.mkdirSync(DATA_DIR, { recursive: true })
}

export async function GET(request: NextRequest) {
    const searchParams = request.nextUrl.searchParams
    const key = searchParams.get('key')
    const folder = searchParams.get('folder') || ''

    if (!key) {
        return NextResponse.json({ error: 'Passkey is required' }, { status: 400 })
    }

    // Sanitize key to prevent directory traversal
    const sanitizedKey = key.replace(/[^a-zA-Z0-9_-]/g, '')
    if (!sanitizedKey) {
        return NextResponse.json({ error: 'Invalid passkey' }, { status: 400 })
    }

    const userDir = path.join(DATA_DIR, sanitizedKey)
    const targetDir = path.join(userDir, folder)

    // Ensure user directory exists
    if (!fs.existsSync(userDir)) {
        // If it doesn't exist, return empty list (it will be created on first upload)
        return NextResponse.json({ files: [] })
    }

    // Security check: ensure targetDir is within userDir
    if (!targetDir.startsWith(userDir)) {
        return NextResponse.json({ error: 'Access denied' }, { status: 403 })
    }

    try {
        if (!fs.existsSync(targetDir)) {
            return NextResponse.json({ files: [] })
        }

        const items = await readdir(targetDir)
        const files = await Promise.all(items.map(async (item) => {
            const itemPath = path.join(targetDir, item)
            const stats = await stat(itemPath)
            const relativePath = path.relative(userDir, itemPath)

            // Read content for text-based files (JSON, LaTeX, Dart, etc.)
            let content = undefined
            const ext = path.extname(item).toLowerCase()
            const textExtensions = ['.json', '.tex', '.dart', '.txt', '.md', '.html', '.css', '.js', '.ts', '.jsx', '.tsx']

            if (!stats.isDirectory() && textExtensions.includes(ext)) {
                try {
                    const fileContent = await fs.promises.readFile(itemPath, 'utf-8')
                    content = fileContent
                } catch (err) {
                    console.error(`Error reading ${item}:`, err)
                }
            }

            return {
                name: item,
                type: stats.isDirectory() ? 'folder' : 'file',
                size: stats.size,
                modified: stats.mtime.toISOString(),
                path: relativePath,
                extension: path.extname(item).substring(1),
                ...(content !== undefined && { content })
            }
        }))

        return NextResponse.json({ files })
    } catch (error) {
        console.error('Error listing files:', error)
        return NextResponse.json({ error: 'Failed to list files' }, { status: 500 })
    }
}

export async function POST(request: NextRequest) {
    try {
        const contentType = request.headers.get('content-type')

        // Handle JSON body (for save_file action)
        if (contentType?.includes('application/json')) {
            const body = await request.json()
            // Support both 'passkey' and 'key' for backwards compatibility
            const { passkey, key, action, fileName, content, folder = '' } = body
            const actualKey = passkey || key

            if (!actualKey) {
                return NextResponse.json({ error: 'Passkey is required' }, { status: 400 })
            }

            if (action === 'save_file') {
                if (!fileName || content === undefined || content === null) {
                    console.log('Save file validation failed:', { fileName, contentLength: content?.length || 0 })
                    return NextResponse.json({ error: 'fileName and content are required' }, { status: 400 })
                }

                const sanitizedKey = actualKey.replace(/[^a-zA-Z0-9_-]/g, '')
                const userDir = path.join(DATA_DIR, sanitizedKey)
                const targetDir = path.join(userDir, folder)

                // Ensure directories exist
                await mkdir(targetDir, { recursive: true })

                const filePath = path.join(targetDir, fileName)

                // Debug logging
                console.log(`Saving file: ${filePath}, content length: ${content.length}`)

                await writeFile(filePath, content, 'utf-8')

                // Note: Auto-PDF generation is disabled to avoid external API dependencies
                // Users can manually compile LaTeX files using the TextEditor's "Compile" button

                return NextResponse.json({ success: true })
            }

            return NextResponse.json({ error: 'Unknown action' }, { status: 400 })
        }

        // Handle FormData (for file uploads)
        const formData = await request.formData()
        const file = formData.get('file') as File
        const key = formData.get('key') as string
        const folder = formData.get('folder') as string || ''

        if (!key) {
            return NextResponse.json({ error: 'Passkey is required' }, { status: 400 })
        }

        if (!file) {
            return NextResponse.json({ error: 'No file provided' }, { status: 400 })
        }

        const sanitizedKey = key.replace(/[^a-zA-Z0-9_-]/g, '')
        const userDir = path.join(DATA_DIR, sanitizedKey)
        const targetDir = path.join(userDir, folder)

        // Ensure directories exist
        await mkdir(targetDir, { recursive: true })

        const buffer = Buffer.from(await file.arrayBuffer())
        const filePath = path.join(targetDir, file.name)

        await writeFile(filePath, buffer)

        return NextResponse.json({ success: true })
    } catch (error) {
        console.error('Error in POST handler:', error)
        return NextResponse.json({ error: 'Operation failed' }, { status: 500 })
    }
}

export async function DELETE(request: NextRequest) {
    const searchParams = request.nextUrl.searchParams
    const key = searchParams.get('key')
    const filePathParam = searchParams.get('path')

    if (!key || !filePathParam) {
        return NextResponse.json({ error: 'Passkey and path are required' }, { status: 400 })
    }

    const sanitizedKey = key.replace(/[^a-zA-Z0-9_-]/g, '')
    const userDir = path.join(DATA_DIR, sanitizedKey)
    const targetPath = path.join(userDir, filePathParam)

    // Security check
    if (!targetPath.startsWith(userDir)) {
        return NextResponse.json({ error: 'Access denied' }, { status: 403 })
    }

    try {
        if (fs.existsSync(targetPath)) {
            await unlink(targetPath)
            return NextResponse.json({ success: true })
        } else {
            return NextResponse.json({ error: 'File not found' }, { status: 404 })
        }
    } catch (error) {
        console.error('Error deleting file:', error)
        return NextResponse.json({ error: 'Delete failed' }, { status: 500 })
    }
}