// Copyright (C) 2020 Marius Schellenberger

package pve

import (
	"bytes"
	"context"
	"crypto/tls"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"net"
	"net/http"
	"net/http/httputil"
	"os"
	"strconv"
	"strings"
	"sync"
	"time"
)

/*
type BackoffFunc func(retries int) time.Duration

func ConstantBackoff(d time.Duration) BackoffFunc {
	return func(_ int) time.Duration {
		return d
	}
}

func ExponentialBackoff(b float64, d time.Duration) BackoffFunc {
	return func(retries int) time.Duration {
		return time.Duration(math.Pow(b, float64(retries))) * d
	}
}
*/

type Client struct {
	sync.Mutex
	endpoints []string
	username  string
	password  string
	session   session
	//pollInterval time.Duration
	//backoffFunc  BackoffFunc
	httpClient  *http.Client
	debugWriter io.Writer
	insecure    bool

	Server  ServerClient
	Task    TaskClient
	Pool    PoolClient
	Node    NodeClient
	Snippet SnippetClient
}

type session struct {
	Username            string    `json:"username"`
	Ticket              string    `json:"ticket"`
	CSRFPreventionToken string    `json:"CSRFPreventionToken"`
	Time                time.Time `json:"-"`
}

type ClientOption func(*Client)

func WithEndpoint(endpoint string) ClientOption {
	return func(client *Client) {
		client.endpoints = append(client.endpoints, strings.TrimRight(endpoint, "/"))
	}
}

func WithEndpoints(endpoints []string) ClientOption {
	return func(client *Client) {
		for _, e := range endpoints {
			client.endpoints = append(client.endpoints, strings.TrimRight(e, "/"))
		}
	}
}

/*
func WithPollInterval(pollInterval time.Duration) ClientOption {
	return func(client *Client) {
		client.pollInterval = pollInterval
	}
}

func WithBackoffFunc(f BackoffFunc) ClientOption {
	return func(client *Client) {
		client.backoffFunc = f
	}
}
*/

func WithDebugWriter(debugWriter io.Writer) ClientOption {
	return func(client *Client) {
		client.debugWriter = debugWriter
	}
}

func WithHTTPClient(httpClient *http.Client) ClientOption {
	return func(client *Client) {
		client.httpClient = httpClient
	}
}

func WithInsecureClient(insecure bool) ClientOption {
	return func(client *Client) {
		client.insecure = insecure
	}
}

func WithCredentials(username, password string) ClientOption {
	return func(client *Client) {
		client.username = username
		client.password = password
	}
}

var (
	ErrMissingEndpointsEnv = errors.New("missing environment variable PVE_ENDPOINTS")
	ErrMissingUserEnv      = errors.New("missing environment variable PVE_USER")
	ErrMissingPasswordEnv  = errors.New("missing environment variable PVE_PASSWORD")

	ErrMissingEndpoints = errors.New("missing Endpoints in config")
	ErrMissingUser      = errors.New("missing User in config")
	ErrMissingPassword  = errors.New("missing Password in config")
)

type Config struct {
	Endpoints []string `json:"endpoints"`
	User      string   `json:"user"`
	Password  string   `json:"password"`
	Insecure  bool     `json:"insecure"`
}

func ClientOptionsFromConfig(cfg Config) (options []ClientOption, err error) {
	if len(cfg.Endpoints) == 0 {
		err = ErrMissingEndpoints
		return
	}
	if cfg.User == "" {
		err = ErrMissingUser
		return
	}
	if cfg.Password == "" {
		err = ErrMissingPassword
		return
	}
	options = []ClientOption{
		WithEndpoints(cfg.Endpoints),
		WithCredentials(cfg.User, cfg.Password),
		WithInsecureClient(cfg.Insecure),
	}
	return
}

func ClientOptionsFromEnv() (options []ClientOption, err error) {
	endpoints := os.Getenv("PVE_ENDPOINTS")
	if endpoints == "" {
		err = ErrMissingEndpointsEnv
		return
	}
	user := os.Getenv("PVE_USER")
	if user == "" {
		err = ErrMissingUserEnv
		return
	}

	pass := os.Getenv("PVE_PASSWORD")
	if pass == "" {
		err = ErrMissingPasswordEnv
		return
	}

	insecure, _ := strconv.ParseBool(os.Getenv("PVE_INSECURE"))

	options = []ClientOption{
		WithEndpoints(strings.Split(endpoints, ",")),
		WithCredentials(user, pass),
		WithInsecureClient(insecure),
	}
	return
}

func NewClient(options ...ClientOption) *Client {
	client := &Client{}
	/*
		endpoint: Endpoint,
		backoffFunc:  ExponentialBackoff(2, 500*time.Millisecond),
		pollInterval: 500 * time.Millisecond,
	}*/

	for _, option := range options {
		option(client)
	}

	if client.httpClient == nil {
		client.httpClient = &http.Client{Transport: &http.Transport{
			DialContext: (&net.Dialer{
				Timeout: 30 * time.Second,
			}).DialContext,
			TLSClientConfig: &tls.Config{
				InsecureSkipVerify: client.insecure,
			},
		}}
	}

	client.Server = ServerClient{client: client}
	client.Task = TaskClient{client: client}
	client.Pool = PoolClient{client: client}
	client.Node = NodeClient{client: client}
	client.Snippet = SnippetClient{client: client}

	return client
}
func (c *Client) getEndpoint() string {
	if len(c.endpoints) == 0 {
		return ""
	}
	return c.endpoints[0]
}

func (c *Client) Auth() (err error) {
	if !time.Now().After(c.session.Time) {
		return
	}
	c.Lock()
	defer c.Unlock()
	if !time.Now().After(c.session.Time) {
		return
	}
	u := c.getEndpoint() + "/access/ticket"
	body := httpbody{"username": c.username, "password": c.password}
	r, err := http.NewRequest("POST", u, body.Reader())
	if err != nil {
		return
	}
	resp, err := c.httpClient.Do(r)
	if err != nil {
		return
	}
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("api authentication failed: %w", errors.New(resp.Status))
	}
	err = unwrapData(resp, &c.session)
	if err != nil {
		return
	}
	c.session.Time = time.Now().Add(time.Hour)
	return
}

func (c *Client) NewRequest(ctx context.Context, method, path string, body io.Reader) (*http.Request, error) {
	err := c.Auth()
	if err != nil {
		return nil, err
	}
	url := c.getEndpoint() + path
	req, err := http.NewRequest(method, url, body)
	if err != nil {
		return nil, err
	}
	req.AddCookie(&http.Cookie{Name: "PVEAuthCookie", Value: c.session.Ticket})
	if method != "GET" {
		req.Header.Add("CSRFPreventionToken", c.session.CSRFPreventionToken)
	}
	req = req.WithContext(ctx)
	return req, nil
}

var HTTPErr = errors.New("http error")

func (c *Client) Do(r *http.Request, v interface{}) (resp *http.Response, err error) {
	if c.debugWriter != nil {
		dumpReq, err := httputil.DumpRequestOut(r, true)
		if err != nil {
			return &http.Response{}, err
		}
		fmt.Fprintf(c.debugWriter, "--- Request:\n%s\n\n", dumpReq)
	}
	resp, err = c.httpClient.Do(r)
	if err != nil {
		return
	}
	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		resp.Body.Close()
		return
	}
	resp.Body.Close()
	resp.Body = ioutil.NopCloser(bytes.NewReader(body))

	if c.debugWriter != nil {
		dumpResp, err := httputil.DumpResponse(resp, true)
		if err != nil {
			return resp, err
		}
		fmt.Fprintf(c.debugWriter, "--- Response:\n%s\n\n", dumpResp)
	}

	err = unwrapData(resp, v)
	if resp.StatusCode >= 400 && resp.StatusCode <= 599 {
		if err != nil {
			err = fmt.Errorf("%w: %s: %s", HTTPErr, errors.New(resp.Status), err.Error())
			return
		}
		err = fmt.Errorf("%w: %s", HTTPErr, errors.New(resp.Status))
	}
	return
}