const State = require('../State')
const axios = require('axios')

class DownloadState extends State {
    static get services() {
        return [...super.services, 'output']
    }

    async apply() {
        if ( !(await this.check()) ) {
            const path = await this._path()
            if ( !this._config.method ) this._config.method = 'get'
            else this._config.method = this._config.method.toLowerCase()

            if ( !this._config.source ) throw new Error('Missing source config for DownloadState.')
            try {
                const res = await axios({
                    method: this._config.method,
                    url: this._config.source,
                    responseType: 'stream',
                })

                const write_stream = await path.open_write_stream()
                await res.data.pipe(write_stream)
            } catch(e) {
                this.output.error('Error encountered while fetching data for DownloadState.')
                throw e
            }
        }
    }

    async check() {
        const path = await this._path()
        await path.classify()
        return path.is_file()
    }

    async reverse() {
        if ( await this.check() ) {
            const path = await this._path()
            await path.unlink()
        }
    }

    async _path() {
        if ( !this._config.path ) throw new Error('Missing path config for DownloadState.')
        return this._host.get_path(this._config.path)
    }

    failure_message() {
        return `The downloaded file "${this._config.path}" does not exist on host "${this._host.name}."`
    }

    check_message() {
        return this.failure_message()
    }
}

module.exports = exports = DownloadState