package discord

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"

	"github.com/pkg/errors"
)

type Token struct {
	AccessToken  string `json:"access_token"`
	TokenType    string `json:"token_type"`
	ExpiresIn    int    `json:"expires_in"`
	RefreshToken string `json:"refresh_token"`
	Scope        string `json:"scope"`
}

const oauthurl string = "https://discord.com/oauth2/authorize"
const apiurl string = "https://discord.com/api/v10"

func GetOAuthLink(cfg *Config, state, trustedHost string) (string, error) {
	if cfg == nil {
		return "", errors.New("cfg cannot be nil")
	}
	if state == "" {
		return "", errors.New("state cannot be empty")
	}
	if trustedHost == "" {
		return "", errors.New("trustedHost cannot be empty")
	}
	values := url.Values{}
	values.Add("response_type", "code")
	values.Add("client_id", cfg.ClientID)
	values.Add("scope", cfg.OAuthScopes)
	values.Add("state", state)
	values.Add("redirect_uri", fmt.Sprintf("%s/%s", trustedHost, cfg.RedirectPath))
	values.Add("prompt", "none")

	return fmt.Sprintf("%s?%s", oauthurl, values.Encode()), nil
}

func AuthorizeWithCode(cfg *Config, code, trustedHost string) (*Token, error) {
	if code == "" {
		return nil, errors.New("code cannot be empty")
	}
	if cfg == nil {
		return nil, errors.New("config cannot be nil")
	}
	if trustedHost == "" {
		return nil, errors.New("trustedHost cannot be empty")
	}
	// Prepare form data
	data := url.Values{}
	data.Set("grant_type", "authorization_code")
	data.Set("code", code)
	data.Set("redirect_uri", fmt.Sprintf("%s/%s", trustedHost, cfg.RedirectPath))
	// Create request
	req, err := http.NewRequest(
		"POST",
		apiurl+"/oauth2/token",
		strings.NewReader(data.Encode()),
	)
	if err != nil {
		return nil, errors.Wrap(err, "failed to create request")
	}
	// Set headers
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")

	// Set basic auth (client_id and client_secret)
	req.SetBasicAuth(cfg.ClientID, cfg.ClientSecret)
	// Execute request
	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		return nil, errors.Wrap(err, "failed to execute request")
	}
	defer resp.Body.Close()
	// Read response body
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, errors.Wrap(err, "failed to read response body")
	}
	// Check status code
	if resp.StatusCode != http.StatusOK {
		return nil, errors.Errorf("discord API returned status %d: %s", resp.StatusCode, string(body))
	}
	// Parse JSON response
	var tokenResp Token
	if err := json.Unmarshal(body, &tokenResp); err != nil {
		return nil, errors.Wrap(err, "failed to parse token response")
	}
	return &tokenResp, nil
}

func RefreshToken(cfg *Config, token *Token) (*Token, error) {
	if token == nil {
		return nil, errors.New("token cannot be nil")
	}
	if cfg == nil {
		return nil, errors.New("config cannot be nil")
	}
	// Prepare form data
	data := url.Values{}
	data.Set("grant_type", "refresh_token")
	data.Set("refresh_token", token.RefreshToken)
	// Create request
	req, err := http.NewRequest(
		"POST",
		apiurl+"/oauth2/token",
		strings.NewReader(data.Encode()),
	)
	if err != nil {
		return nil, errors.Wrap(err, "failed to create request")
	}
	// Set headers
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")

	// Set basic auth (client_id and client_secret)
	req.SetBasicAuth(cfg.ClientID, cfg.ClientSecret)
	// Execute request
	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		return nil, errors.Wrap(err, "failed to execute request")
	}
	defer resp.Body.Close()
	// Read response body
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, errors.Wrap(err, "failed to read response body")
	}
	// Check status code
	if resp.StatusCode != http.StatusOK {
		return nil, errors.Errorf("discord API returned status %d: %s", resp.StatusCode, string(body))
	}
	// Parse JSON response
	var tokenResp Token
	if err := json.Unmarshal(body, &tokenResp); err != nil {
		return nil, errors.Wrap(err, "failed to parse token response")
	}
	return &tokenResp, nil
}

func RevokeToken(cfg *Config, token *Token) error {
	if token == nil {
		return errors.New("token cannot be nil")
	}
	if cfg == nil {
		return errors.New("config cannot be nil")
	}
	// Prepare form data
	data := url.Values{}
	data.Set("token", token.AccessToken)
	data.Set("token_type_hint", "access_token")
	// Create request
	req, err := http.NewRequest(
		"POST",
		apiurl+"/oauth2/token/revoke",
		strings.NewReader(data.Encode()),
	)
	if err != nil {
		return errors.Wrap(err, "failed to create request")
	}
	// Set headers
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")

	// Set basic auth (client_id and client_secret)
	req.SetBasicAuth(cfg.ClientID, cfg.ClientSecret)
	// Execute request
	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		return errors.Wrap(err, "failed to execute request")
	}
	defer resp.Body.Close()
	// Check status code
	if resp.StatusCode != http.StatusOK {
		return errors.Errorf("discord API returned status %d", resp.StatusCode)
	}
	return nil
}