import * as path from 'path'
import * as vscode from 'vscode'
import * as fs from 'fs'
import { LanguageClient, LanguageClientOptions, ServerOptions, TransportKind } from 'vscode-languageclient/node'

let client: LanguageClient

function findInSystemPath(binary: string): string | null {
    const pathDirs = process.env.PATH?.split(path.delimiter) || []

    for (const dir of pathDirs) {
        const fullPath = path.join(dir, binary)
        if (fs.existsSync(fullPath)) {
            return fullPath
        }
    }
    return null
}

function findExecutable(context: vscode.ExtensionContext, configPath: string | undefined, bundledRelativePath: string, systemBinaryName: string): string | null {
    // 1. 优先使用用户配置的路径
    if (configPath) {
        return configPath
    }

    // 2. 查找插件自带的可执行文件
    const bundledPath = context.asAbsolutePath(bundledRelativePath)
    if (fs.existsSync(bundledPath)) {
        return bundledPath
    }

    // 3. 从系统 PATH 查找
    return findInSystemPath(systemBinaryName)
}

export function activate(context: vscode.ExtensionContext) {
    const config = vscode.workspace.getConfiguration('tsl')
    let serverArguments = config.get<string[]>('server.arguments') || []

    const serverBinary = process.platform === 'win32' ? 'tsl-server.exe' : 'tsl-server'
    let serverExe = findExecutable(
        context,
        config.get<string>('server.executable'),
        path.join('bin', serverBinary),
        serverBinary
    )

    if (!serverExe) {
        vscode.window.showErrorMessage(
            "Cannot find tsl-server. Please install it globally or configure 'tsl.server.executable' in settings."
        )
        return
    }

    const interpreterBinary = process.platform === 'win32' ? 'tsl.exe' : 'tsl'
    let interpreterExe = findExecutable(
        context,
        config.get<string>('interpreter.executable'),
        "",
        interpreterBinary
    )

    if (!interpreterExe) {
        vscode.window.showWarningMessage(
            "Cannot find TSL interpreter. Some features may not work. Please install it globally or configure 'tsl.interpreter.executable' in settings."
        )
    }

    if (interpreterExe) {
        let interpreterDir = path.dirname(interpreterExe)
        interpreterDir = interpreterDir.replace(/\\/g, '/') + '/'
        serverArguments = serverArguments.filter(arg => !arg.startsWith('--interpreter='))
        serverArguments.push(`--interpreter=${interpreterDir}`)
    }

    const runArgs = [...serverArguments]
    const debugArgs = serverArguments.map(arg => arg.startsWith('--log=') ? '--log=trace' : arg)
    if (!debugArgs.some(arg => arg.startsWith('--log='))) debugArgs.push('--log=trace')
    if (!debugArgs.includes('--log-stderr')) debugArgs.push('--log-stderr')

    const serverOptions: ServerOptions = {
        run: { command: serverExe, transport: TransportKind.stdio, args: runArgs },
        debug: { command: serverExe, transport: TransportKind.stdio, args: debugArgs }
    }

    const clientOptions: LanguageClientOptions = {
        documentSelector: [{ scheme: 'file', language: 'tsl' }],
        synchronize: {
            fileEvents: vscode.workspace.createFileSystemWatcher('**/*.tsl')
        }
    }

    client = new LanguageClient(
        'tslLanguageServer',
        'TSL Language Server',
        serverOptions,
        clientOptions
    )

    // 保存解释器路径到上下文，供其他命令使用
    if (interpreterExe) {
        context.globalState.update('tsl.interpreterPath', interpreterExe)
    }

    client.start()
}

export function deactivate(): Thenable<void> | undefined {
    return client ? client.stop() : undefined
}