package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
)

type AdGuardClient struct {
	BaseURL  string
	Username string
	Password string
	Client   *http.Client
}

func NewAdGuardClient() (*AdGuardClient, error) {
	baseURL := os.Getenv("ADGUARD_URL")
	user := os.Getenv("ADGUARD_USER")
	pass := os.Getenv("ADGUARD_PASSWORD")

	if baseURL == "" || user == "" || pass == "" {
		return nil, fmt.Errorf("fehlende Umgebungsvariablen")
	}

	return &AdGuardClient{
		BaseURL:  baseURL,
		Username: user,
		Password: pass,
		Client:   &http.Client{},
	}, nil
}

func (c *AdGuardClient) Login() error {
	data := map[string]string{"name": c.Username, "password": c.Password}
	return c.post("/control/login", data, nil)
}

func (c *AdGuardClient) GetRewrites() ([]Rewrite, error) {
	resp, err := c.Client.Get(c.BaseURL + "/control/rewrite/list")
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	var list []Rewrite
	if err := json.NewDecoder(resp.Body).Decode(&list); err != nil {
		return nil, err
	}
	return list, nil
}

func (c *AdGuardClient) AddRewrite(r Rewrite) error {
	return c.post("/control/rewrite/add", r, nil)
}

func (c *AdGuardClient) DeleteRewrite(r Rewrite) error {
	return c.post("/control/rewrite/delete", r, nil)
}

func (c *AdGuardClient) UpdateRewrite(oldR, newR Rewrite) error {
	payload := map[string]Rewrite{"target": oldR, "update": newR}
	return c.put("/control/rewrite/update", payload, nil)
}

func (c *AdGuardClient) post(path string, body any, result any) error {
	return c.doRequest("POST", path, body, result)
}

func (c *AdGuardClient) put(path string, body any, result any) error {
	return c.doRequest("PUT", path, body, result)
}

func (c *AdGuardClient) doRequest(method, path string, body any, result any) error {
	b, err := json.Marshal(body)
	if err != nil {
		return err
	}

	req, err := http.NewRequest(method, c.BaseURL+path, bytes.NewReader(b))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")

	resp, err := c.Client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 400 {
		body, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("Fehler %d: %s", resp.StatusCode, string(body))
	}

	if result != nil {
		return json.NewDecoder(resp.Body).Decode(result)
	}
	return nil
}