import * as Logger from 'log4js'
import * as path from "path";
import { promises as fs } from "fs"
import * as git from "simple-git/promise"
import * as trash from "trash"


Logger.configure({
    appenders: 
    {
    "admin/extension": { type: 'stdout' },
    //app: { type: 'file', filename: 'application.log' }
    },
    categories: 
    {
    default: { appenders: [ 'admin/extension' ], level: 'debug' }
    }
})
const exec = require('child-process-promise').exec;
const logger = Logger.getLogger("admin/updatemanager") 

type SharedStatus = {
    name: string
    installed?: boolean
    outdated?: boolean
}

abstract class Extension<Status extends SharedStatus>{
    constructor(
        protected name: string
    ){}

    /**
     * the generic Status object
     */
    protected async status():Promise<Status>{
        const installed = await this.isInstalled()
        const outdated = await this.isOutdated()
        return <Status>{ name: this.name, installed: installed, outdated: outdated }
    }

    /**
     * true => extension was installed
     * false => extension was not install
     * undefined => signals error
     */
    abstract async install():Promise<boolean | undefined>

    /**
     * reverts the install procedure
     */
    abstract async uninstall():Promise<void>

    /**
     * true => an update was performed
     * false => no update was performed
     * undefined => signals error
     */
    abstract async update(force?: boolean): Promise<boolean | undefined>

    /**
     * true => update would install a newer version
     * false => nothing would be updated if update would be performed
     * undefined => signals error
     */
    abstract async isOutdated():Promise<boolean | undefined>

    /**
     * promises a boolean
     * true => install would do nothing would it be called
     * false => install would try to install the newest extension
     * undefined => signals error
     */
    abstract async isInstalled():Promise<boolean | undefined>
}

export type FSStatus = SharedStatus & {
    prefix: string 
    empty?: boolean
}

export abstract class FSExtension<Status extends FSStatus> extends Extension<Status>{
    constructor(
        name: string, 
        protected readonly prefix: string){
            super(name)
    }

    public async status(): Promise<Status>{
        const shdStatus = await super.status()
        const empty = await this.isEmpty()
        return <Status>{...shdStatus, prefix: this.prefix, empty: empty}
    }

    public async install():Promise<boolean>{
        const installed = await this.isInstalled()
        if (!installed) {
            logger.info('Installing extension to', path.resolve(this.prefix, this.name))
            await fs.mkdir(path.resolve(this.prefix, this.name), {recursive: true})
            return true
        }
        logger.warn('Extension already installed at', path.resolve(this.prefix, this.name))
        return false
    }

    public async uninstall(): Promise<void>{
        logger.info('Uninstalling extension from', path.resolve(this.prefix, this.name))
        return await trash(path.resolve(this.prefix, this.name))
    }

    public async update(force?: boolean): Promise<boolean | undefined>{
        if (force) await this.uninstall()
        return await this.install()
    }

    public async isEmpty(): Promise<boolean | undefined>{
        if (!this.isInstalled()) return true
        try {
            const files = await fs.readdir(path.resolve(this.prefix, this.name))
            return files.length === 0
        } catch (error) {
            logger.warn('TODO')
            return
        }
    }

    public async isInstalled(): Promise<boolean>{
        try {
            await fs.access(path.resolve(this.prefix, this.name))
            return true
        } catch (error) {
            return false
        }
    }
}

type NPMStatus = FSStatus & {
    latest?: string,
    current?: string,
    author?: string
}

export class NPMExtension extends FSExtension<NPMStatus>{

    constructor(
        pkgName: string,
        prefix: string){
        super(pkgName, prefix)
    }

    public async status(): Promise<NPMStatus> {

        const fsStatus = await super.status()
        const latest = await this.getLatestVersion()
        const author = await this.getAuthor()
        const current = await this.getCurrentVersion()
        return {  
            ...fsStatus, 
            latest: latest,
            author: author,
            current: current
        }
    }

    public async install(): Promise<boolean> {
        super.install()
        logger.info("npm install", this.name, 'to', path.resolve(this.prefix, this.name))
        const { error, stdout, stderr } = await exec('npm install --prefix '+ this.prefix + ' ' + this.name)
        if (error !== null) {
            logger.warn('npm install', this.name, 'from prefix', this.prefix, 'stderr:', stderr)
            return false
        } else {
            logger.info('npm install', this.name, 'from prefix', this.prefix, 'stdout:', stdout)
            return true
        }
    }
    
    public async uninstall(force?: boolean): Promise<void> {
        super.uninstall()
        logger.info("npm uninstall", this.name, 'from', path.resolve(this.prefix, this.name))
        const { error, stdout, stderr } = await exec('npm uninstall --prefix '+ this.prefix + ' ' + this.name)
        if (error) {
            logger.warn('npm uninstall', this.name, 'from prefix', this.prefix, 'stderr:', stderr)
        } else {
            logger.info('npm uninstall', this.name, 'from prefix', this.prefix, 'stdout:', stdout)
        }
    }

    public async update(force?: boolean): Promise<boolean> {
        super.update(force)
        logger.info("npm update", path.resolve(this.prefix, this.name))
        const { error, stdout, stderr } = await exec('npm update --prefix '+ this.prefix + ' ' + this.name)
        if (error) {
            logger.warn('npm update', this.name, 'from prefix', this.prefix, 'stderr:', stderr)
            return false
        } else {
            logger.info('npm update', this.name, 'from prefix', this.prefix, 'stdout:', stdout)
            return true
        }
    }

    public async isOutdated(): Promise<boolean | undefined> {
        try {
            const { 
                error, 
                stdout, 
                stderr } = await exec('npm outdated --prefix ' + this.prefix + " --json" + ' ' + this.name)
            if (error) throw new Error(stderr)
            if (Object.keys(JSON.parse(stdout)).length > 0) return true
            else return false
        } catch (error) {
            logger.warn('npm outdated', this.name, 'from prefix', this.prefix, 'stderr:', error)
            return
        }
    }

    private async getAuthor(): Promise<string | undefined>{
        const { 
            error, 
            stdout, 
            stderr } = await exec('npm author ls --prefix ' + this.prefix + ' ' + this.name)

        if(error){
            logger.warn(stderr)
            return
        } else {
            logger.info(stdout)
            return stdout
        }
    }

    private async getLatestVersion(): Promise<string | undefined>{
        const { 
            error, 
            stdout, 
            stderr } = await exec('npm view --prefix ' + this.prefix + ' ' + this.name + " version")

        if(error){
            logger.warn(stderr)
            return
        } else {
            logger.info(stdout)
            return stdout
        }
    }

    private async getCurrentVersion(): Promise<string | undefined>{
        return //TODO
    }
}

export type GitStatus = FSStatus & {
    branch?: string
    remote?: string
    latest?: string
}

export class GitExtension<Status extends GitStatus> extends FSExtension<Status>{
    protected repo: git.SimpleGit
    constructor(
        repoName:string,
        localPrefix:string,
        protected gitCloneURL: string,
        protected credentials?: [string, string]
    ){
        super(repoName, localPrefix)
    }

    public async status(): Promise<Status>{
        const fsStatus = await super.status()

        return {  
            ...fsStatus, 
            branch: 'wat',
            remote: this.gitCloneURL,
            latest: 'kek'
        }
    }

    public async install(): Promise<boolean> {
        if (super.install()){
            if (this.credentials){

            } else {

            }
        } else {

        }
    }
    

    public async update(): Promise<boolean> {
        return true // do git pull remote origin && git checkout 
    }

    public async isOutdated(): Promise<boolean> {
        return true
    }
}

export type PluginStatus = GitStatus & {
    hasFrontend: boolean,
    hasBackend: boolean,
    isFrontendLoaded: boolean,
    isBackendLoaded: boolean
}

export class PluginExtension<Status extends GitStatus> extends GitExtension<Status> {
    protected frontendLoaded: boolean
    protected backendLoaded: boolean

    constructor(
        pluginName: string,
        gitCloneURL: string,
        localPrefix: string = './plugins',
        credentials?: [string, string],
        protected hasBackend: boolean = true,
        protected hasFrontend: boolean = true){
        super(pluginName,localPrefix,gitCloneURL,credentials)
    }

    public async load(): Promise<void>{
        if (this.hasFrontend) await this.loadFrontend()
        if (this.hasBackend) await this.loadBackend()
    }

    public async loadFrontend(): Promise<void>{
        return //TODO
    }

    public async loadBackend(): Promise<void>{
        return //TODO
    }

    public async unload(): Promise<void>{
        if (this.hasFrontend) await this.unloadFrontend()
        if (this.hasBackend) await this.unloadBackend()
    }

    public async unloadFrontend(): Promise<void>{
        return //TODO
    }

    public async unloadBackend(): Promise<void>{
        return //TODO
    }

}