// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.

import * as fsapi from "fs-extra"
import { Disposable, env, LogOutputChannel, workspace } from "vscode"
import { State } from "vscode-languageclient"
import {
    LanguageClient,
    LanguageClientOptions,
    RevealOutputChannelOn,
    ServerOptions
} from "vscode-languageclient/node"
import { DEBUG_SERVER_SCRIPT_PATH, SERVER_SCRIPT_PATH } from "./constants"
import { traceError, traceInfo, traceVerbose } from "./log/logging"
import { getDebuggerPath } from "./python"
import {
    getExtensionSettings,
    getGlobalSettings,
    getWorkspaceSettings,
    ISettings
} from "./settings"
import { getLSClientTraceLevel, getProjectRoot } from "./utilities"
import { isVirtualWorkspace } from "./vscodeapi"

export type IInitOptions = { settings: ISettings[]; globalSettings: ISettings }

let _disposables: Disposable[] = []

export function disposeServerResources(): void {
    _disposables.forEach((disposable) => disposable.dispose())
    _disposables = []
}

async function createServer(
    settings: ISettings,
    serverId: string,
    serverName: string,
    outputChannel: LogOutputChannel,
    initializationOptions: IInitOptions
): Promise<LanguageClient> {
    const command = settings.interpreter[0]
    if (!command) {
        throw new Error("No Python interpreter is configured for the language server.")
    }
    const cwd = settings.cwd

    // Set debugger path needed for debugging python code.
    const newEnv = { ...process.env }
    const isDebugScript = await fsapi.pathExists(DEBUG_SERVER_SCRIPT_PATH)
    const debugRequested = newEnv.USE_DEBUGPY?.toLowerCase() === "true"
    if (debugRequested && !isDebugScript) {
        throw new Error(`Python debug bootstrap not found: ${DEBUG_SERVER_SCRIPT_PATH}`)
    }

    const debuggerPath = debugRequested ? await getDebuggerPath() : undefined
    if (debugRequested && !debuggerPath) {
        throw new Error(
            "Python debugging was requested, but the Python Debugger extension did not provide debugpy."
        )
    }
    if (debugRequested && debuggerPath) {
        newEnv.DEBUGPY_PATH = debuggerPath
    } else {
        newEnv.USE_DEBUGPY = "False"
    }

    // Set import strategy
    newEnv.LS_IMPORT_STRATEGY = settings.importStrategy

    // Set notification type
    newEnv.LS_SHOW_NOTIFICATION = settings.showNotifications

    const serverScript = debugRequested ? DEBUG_SERVER_SCRIPT_PATH : SERVER_SCRIPT_PATH
    const interpreterArgs = settings.interpreter.slice(1)
    if (debugRequested && !interpreterArgs.includes("-Xfrozen_modules=off")) {
        interpreterArgs.push("-Xfrozen_modules=off")
    }
    const args = interpreterArgs.concat([serverScript])
    traceInfo(`Python debug mode: ${debugRequested ? "enabled" : "disabled"}`)
    traceInfo(`Server run command: ${[command, ...args].join(" ")}`)

    const serverOptions: ServerOptions = {
        command,
        args,
        options: { cwd, env: newEnv }
    }

    // Options to control the language client
    const tclFileWatcher = workspace.createFileSystemWatcher("**/*.tcl")
    const clientOptions: LanguageClientOptions = {
        // Register the server for python documents
        documentSelector: isVirtualWorkspace()
            ? [{ language: "tcl" }]
            : [
                  { scheme: "file", language: "tcl" },
                  { scheme: "untitled", language: "tcl" },
                  { scheme: "vscode-notebook", language: "tcl" },
                  { scheme: "vscode-notebook-cell", language: "tcl" }
              ],
        outputChannel: outputChannel,
        traceOutputChannel: outputChannel,
        revealOutputChannelOn: RevealOutputChannelOn.Never,
        synchronize: {
            fileEvents: tclFileWatcher
        },
        initializationOptions
    }

    _disposables.push(tclFileWatcher)
    return new LanguageClient(serverId, serverName, serverOptions, clientOptions)
}

export async function restartServer(
    serverId: string,
    serverName: string,
    outputChannel: LogOutputChannel,
    lsClient?: LanguageClient
): Promise<LanguageClient | undefined> {
    if (lsClient) {
        traceInfo(`Server: Stop requested`)
        await lsClient.stop()
        disposeServerResources()
    }
    const projectRoot = await getProjectRoot()
    const workspaceSetting = await getWorkspaceSettings(serverId, projectRoot, true)

    try {
        const newLSClient = await createServer(
            workspaceSetting,
            serverId,
            serverName,
            outputChannel,
            {
                settings: await getExtensionSettings(serverId, true),
                globalSettings: await getGlobalSettings(serverId, false)
            }
        )
        traceInfo(`Server: Start requested.`)
        _disposables.push(
            newLSClient.onDidChangeState((e) => {
                switch (e.newState) {
                    case State.Stopped:
                        traceVerbose(`Server State: Stopped`)
                        break
                    case State.Starting:
                        traceVerbose(`Server State: Starting`)
                        break
                    case State.Running:
                        traceVerbose(`Server State: Running`)
                        break
                }
            })
        )
        await newLSClient.start()
        const level = getLSClientTraceLevel(outputChannel.logLevel, env.logLevel)
        await newLSClient.setTrace(level)
        return newLSClient
    } catch (ex) {
        traceError(`Server: Start failed: ${ex}`)
        disposeServerResources()
        return undefined
    }
}