package goanilist

import (
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"net/url"
	"time"
)

const API_URL = "https://anilist.co/api/"

var (
	ErrAnilistCoupled    = errors.New("Anilist is already coupled!")
	ErrAnilistNotCoupled = errors.New("Anilist is not coupled")
)

var httpClient = &http.Client{}

type Client struct {
	db           *sql.DB
	user         int
	id           string
	secret       string
	token        string
	refreshToken string
	tokenExpires int64
	IsCoupled    bool
}

func NewClient(db *sql.DB, user int, id, secret string) *Client {
	c := &Client{
		db:     db,
		user:   user,
		id:     id,
		secret: secret,
	}
	err := db.QueryRow("SELECT token, refresh_token, expires_at FROM login.anilist_api_tokens WHERE user_id = $1;", user).Scan(&c.token, &c.refreshToken, &c.tokenExpires)
	c.IsCoupled = err == nil
	return c
}

func (c *Client) AuthorizeURL() string {
	return fmt.Sprintf("%sauth/authorize?grant_type=%s&client_id=%s&response_type=%s",
		API_URL,
		"authorization_pin",
		url.QueryEscape(c.id),
		"pin")
}

func (c *Client) NeedsToRenew() bool {
	t := time.Now().UTC().Unix()
	return t > (c.tokenExpires - 60) //60 seconds of buffer time
}

func (c *Client) CoupleByPin(pin string) error {
	if c.IsCoupled {
		return ErrAnilistCoupled
	}
	res := AccessTokenResult{}
	err := c.post("auth/access_token", url.Values{
		"grant_type":    {"authorization_pin"},
		"client_id":     {c.id},
		"client_secret": {c.secret},
		"code":          {pin},
	}, &res)
	switch res.Error {
	case "invalid_request":
		err = errors.New("Der eingegebene Code ist nicht korrekt. Bitte prüfe, ob du ihn richtig kopiert hast.")
	}
	if err != nil {
		return err
	}
	_, err = c.db.Exec("INSERT INTO login.anilist_api_tokens (user_id, token, refresh_token, expires_at) VALUES ($1, $2, $3, $4);", c.user, res.AccessToken, res.RefreshToken, res.Expires)
	if err != nil {
		return err
	}
	c.token = res.AccessToken
	c.refreshToken = res.RefreshToken
	c.tokenExpires = res.Expires
	return nil
}

func (c *Client) RenewToken() error {
	if !c.IsCoupled {
		return ErrAnilistNotCoupled
	}
	if !c.NeedsToRenew() {
		return nil
	}
	log.Println("Token expired, get new token..")
	res := AccessTokenResult{}
	err := c.post("auth/access_token", url.Values{
		"grant_type":    {"refresh_token"},
		"client_id":     {c.id},
		"client_secret": {c.secret},
		"refresh_token": {c.refreshToken},
	}, &res)
	if err != nil {
		return err
	}
	_, err = c.db.Exec("UPDATE login.anilist_api_tokens SET token = $1, expires_at = $2 WHERE user_id = $3;", res.AccessToken, res.Expires, c.user)
	if err != nil {
		return err
	}
	c.token = res.AccessToken
	c.tokenExpires = res.Expires
	return nil
}

func (c *Client) User() (*UserResult, error) {
	if !c.IsCoupled {
		return nil, ErrAnilistNotCoupled
	}
	if err := c.RenewToken(); err != nil {
		return nil, err
	}
	res := &UserResult{}
	err := c.get("user", res)
	if err != nil {
		return nil, err
	}
	return res, nil
}

func (c *Client) post(path string, values url.Values, result interface{}) error {
	resp, err := http.PostForm(fmt.Sprintf("%s%s", API_URL, path), values)
	if err != nil {
		return err
	}
	return c.handleResponse(resp, path, values, result)
}

func (c *Client) get(path string, result interface{}) error {
	req, err := http.NewRequest("GET", fmt.Sprintf("%s%s", API_URL, path), nil)
	if err != nil {
		return err
	}
	req.Header.Add("Authorization", "Bearer "+c.token)
	resp, err := httpClient.Do(req)
	if err != nil {
		return err
	}
	return c.handleResponse(resp, path, url.Values{}, result)
}

func (c *Client) handleResponse(resp *http.Response, path string, values url.Values, result interface{}) error {
	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return err
	}
	err = json.Unmarshal(body, result)
	if err != nil {
		log.Println(string(body))
		return err
	}
	resErr := result.(APIError).Get()
	resErr.ParseRawError()
	if resp.StatusCode != 200 {
		log.Printf("%s: %v -> %s\n", path, values, resp.Status)
		if resErr.Error != "" {
			log.Printf("%v\n", resErr)
			return errors.New(fmt.Sprintf("%s: %s", resErr.Error, resErr.ErrorMessage))
		} else {
			return errors.New(resp.Status)
		}
	}
	return nil
}