const { Injectable } = require('flitter-di')
const ImplementationError = require('libflitter/errors/ImplementationError')
const PermissionDeniedError = require('../logical/error/PermissionDeniedError')
const CommandNotFoundError = require('../logical/error/CommandNotFoundError')
const FilesystemResourceNotFoundError = require('../logical/error/FilesystemResourceNotFoundError')
const uuid = require('uuid/v4')
const UniversalPath = require('../logical/UniversalPath')
const SystemMetrics = require('../logical/SystemMetrics')

const DNFManager = require('../logical/packages/DNFManager')
const APTManager = require('../logical/packages/APTManager')

const SystemDManager = require('../logical/services/SystemDManager')

class Host extends Injectable {
    static get services() {
        return [...super.services, 'utility']
    }

    _temp_path_command = 'mktemp -d'
    _temp_file_command = 'mktemp'
    _cpu_percentage_command = `grep 'cpu ' /proc/stat | awk '{usage=($2+$4)*100/($2+$4+$5)} END {print usage}'`
    _ram_percentage_command = `free | grep Mem | awk '{print $3/$2 * 100.0}'`
    _mount_point_percentage_command = `df -hl | grep -w '%%MOUNTPOINT%%$' | awk '{print $5}'`
    _list_mount_points_command = `df -hl | grep '/' | awk '{print $6}'`
    _file_directory_delete_command = `rm -rf "%%RESOURCE%%"`
    _resolve_path_command = `readlink -f "%%PATH%%"`
    _reboot_command = `reboot`
    _change_directory_command = `cd "%%PATH%%"`
    _file_directory_permission_fetch_command = `stat -c %a "%%PATH%%"`
    _file_directory_permission_set_command_flat = `chmod %%LEVEL%% "%%PATH%%"`
    _file_directory_permission_set_command_recursive = `chmod -R %%LEVEL%% "%%PATH%%"`
    _file_directory_ownership_fetch_command = `stat -c "%U:%G" "%%PATH%%"`
    _file_directory_ownership_set_command_flat = `chown %%OWNERS%% "%%PATH%%"`
    _file_directory_ownership_set_command_recursive = `chown -R %%OWNERS%% "%%PATH%%"`

    constructor(config) {
        super()
        this.config = config
        this.name = config.name

        if ( config.packages && config.packages.type ) {
            if ( config.packages.type === 'dnf' ) {
                this.packages = new DNFManager(this)
            } else if ( config.packages.type === 'apt' ) {
                this.packages = new APTManager(this)
            } else {
                throw new Error(`Invalid or unknown package manager type: ${config.packages.type}`)
            }
        }

        if ( config.services && config.services.type ) {
            if ( config.services.type === 'systemd' ) {
                this.services = new SystemDManager(this)
            } else {
                throw new Error(`Invalid or unknown service manager type: ${config.services.type}`)
            }
        }
    }

    async execute(command) {
        throw new ImplementationError()
    }

    async open_file_read_stream(file_path) {
        throw new ImplementationError()
    }

    async open_file_write_stream(file_path) {
        throw new ImplementationError()
    }

    async is_alive() {
        try {
            const unique_id = uuid()
            const result = await this.execute(`echo "${unique_id}"`)
            return (result.exit_code === 0 && (result.clean_out.length > 0 && result.clean_out[0] === unique_id))
        } catch (e) {
            return false
        }
    }

    async get_temp_path() {
        const path_string = await this.run_line_result(this._temp_path_command)
        return new UniversalPath(this, path_string, UniversalPath.PATH_TYPE_DIRECTORY)
    }

    async get_temp_file() {
        const file_string = await this.run_line_result(this._temp_file_command)
        return new UniversalPath(this, file_string, UniversalPath.PATH_TYPE_FILE)
    }

    async get_path(local_path) {
        const host_path = new UniversalPath(this, local_path)
        await host_path.classify()
        return host_path
    }

    async metrics() {
        const metric = new SystemMetrics()
        const cpu_percent = Number(await this.run_line_result(this._cpu_percentage_command))
        const ram_percent = Number(await this.run_line_result(this._ram_percentage_command))
        metric.cpu(cpu_percent)
        metric.ram(ram_percent)

        const mount_points = await this.get_mount_points()
        for ( const point of mount_points ) {
            metric.mount(point, await this.get_mountpoint_utilization(point))
        }

        return metric
    }

    async delete_path(resource_path) {
        resource_path = typeof resource_path === 'string' ? resource_path : resource_path.path
        await this.execute(this._file_directory_delete_command.replace('%%RESOURCE%%', resource_path))
    }

    get_directory_change_command(path) {
        if ( typeof path !== 'string' ) path = path.path
        return this._change_directory_command.replace('%%PATH%%', path)
    }

    async resolve_path(resource_path) {
        resource_path = typeof resource_path === 'string' ? resource_path : resource_path.path
        return this.run_line_result(this._resolve_path_command.replace('%%PATH%%', resource_path))
    }

    async get_permissions_for_path(resource_path) {
        resource_path = typeof resource_path === 'string' ? resource_path : resource_path.path
        return this.run_line_result(this._file_directory_permission_fetch_command.replace('%%PATH%%', resource_path))
    }

    async set_permissions_for_path(resource_path, level, recursive = false) {
        resource_path = typeof resource_path === 'string' ? resource_path : resource_path.path
        let cmd
        if ( recursive ) cmd = this._file_directory_permission_set_command_recursive
        else cmd = this._file_directory_permission_set_command_flat
        cmd = cmd.replace('%%PATH%%', resource_path)
        cmd = cmd.replace('%%LEVEL%%', level)
        await this.run(cmd)
    }

    async get_ownership_for_path(resource_path) {
        resource_path = typeof resource_path === 'string' ? resource_path : resource_path.path
        const cmd = this._file_directory_ownership_fetch_command.replace('%%PATH%%', resource_path)
        const result = await this.run_line_result(cmd)
        const parts = result.split(':')
        return {user: parts[0], group: parts[1]}
    }

    async set_ownership_for_path(resource_path, { user, group }, recursive = false) {
        resource_path = typeof resource_path === 'string' ? resource_path : resource_path.path
        let cmd
        if ( recursive ) cmd = this._file_directory_ownership_set_command_recursive
        else cmd = this._file_directory_ownership_set_command_flat
        cmd = cmd.replace('%%PATH%%', resource_path)
        cmd = cmd.replace('%%OWNERS%%', `${user}:${group}`)
        await this.run(cmd)
    }

    async get_mount_points() {
        const result = await this.execute(this._list_mount_points_command)
        if ( result.exit_code !== 0 ) {
            throw new Error('Unable to determine mount points. Command execution error.')
        }

        return result.clean_out
    }

    async get_mountpoint_utilization(mountpoint) {
        const cmd = this._mount_point_percentage_command.replace('%%MOUNTPOINT%%', mountpoint)
        const result = await this.execute(cmd)
        if ( result.exit_code !== 0 ) {
            throw new Error('Unable to determine mount utilization. Command execution error.')
        }

        return Number(result.clean_out[0].replace('%', ''))/100
    }

    async run_line_result(command) {
        const result = await this.execute(command)
        if ( result.exit_code !== 0 || result.clean_out.length < 1 ) {
            const E = this._get_result_error_class(result)
            throw new E('Unable to get line output from command: '+command+'\n'+result.clean_err)
        }
        return this.utility.infer(result.clean_out[0].trim())
    }

    async run(command) {
        const result = await this.execute(command)
        if ( result.exit_code !== 0 ) {
            const E = this._get_result_error_class(result)
            throw new E('Unable to run command: '+command+'\n'+result.clean_err)
        }
        return result
    }

    async list_files_in_directory(local_path) {
        throw new ImplementationError()
    }

    async _cleanup() {}

    async reboot() {
        await this.run_line_result(this._reboot_command)
    }

    _get_result_error_class(result) {
        const both = `${result.clean_out}\n${result.clean_err}`.toLowerCase()
        const access_denied_phrases = [
            'not permitted',
            'access denied',
            'insufficient permission',
            'permission denied'
        ]

        const not_found_phrases = [
            'command not found',
        ]

        const resource_not_found = [
            'no such file',
            'no such directory',
            'no such file or directory',
            'no such directory or file',
        ]

        for ( const phrase of access_denied_phrases ) {
            if ( both.includes(phrase) ) return PermissionDeniedError
        }

        for ( const phrase of not_found_phrases ) {
            if ( both.includes(phrase) ) return CommandNotFoundError
        }

        for ( const phrase of resource_not_found ) {
            if ( both.includes(phrase) ) return FilesystemResourceNotFoundError
        }

        return Error
    }
}

module.exports = exports = Host