package pf

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"strings"
	"time"
)

type Telegram struct {
	token  string
	client *http.Client
}

type tgResponse[T any] struct {
	OK          bool   `json:"ok"`
	Description string `json:"description"`
	Result      T      `json:"result"`
}

type TGUpdate struct {
	UpdateID int64      `json:"update_id"`
	Message  *TGMessage `json:"message"`
}

type TGMessage struct {
	MessageID int64   `json:"message_id"`
	Text      string  `json:"text"`
	Chat      TGChat  `json:"chat"`
	From      *TGUser `json:"from"`
}

type TGChat struct {
	ID int64 `json:"id"`
}

type TGUser struct {
	ID        int64  `json:"id"`
	Username  string `json:"username"`
	FirstName string `json:"first_name"`
	LastName  string `json:"last_name"`
}

func NewTelegram(token string) *Telegram {
	return &Telegram{token: token, client: &http.Client{Timeout: 35 * time.Second}}
}

func (t *Telegram) Enabled() bool {
	return strings.TrimSpace(t.token) != ""
}

func (t *Telegram) SendMessage(ctx context.Context, chatID string, text string) error {
	if !t.Enabled() {
		return nil
	}
	payload := map[string]any{
		"chat_id":                  chatID,
		"text":                     text,
		"parse_mode":               "HTML",
		"disable_web_page_preview": false,
	}
	body, _ := json.Marshal(payload)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, t.apiURL("sendMessage"), bytes.NewReader(body))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")
	resp, err := t.client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	var out tgResponse[json.RawMessage]
	if err := json.NewDecoder(resp.Body).Decode(&out); err != nil {
		return err
	}
	if !out.OK {
		return errors.New(out.Description)
	}
	return nil
}

func (t *Telegram) GetUpdates(ctx context.Context, offset int64) ([]TGUpdate, error) {
	if !t.Enabled() {
		return nil, fmt.Errorf("TG_BOT_TOKEN не задан в k8s/secrets.yaml")
	}
	values := url.Values{}
	values.Set("timeout", "25")
	if offset > 0 {
		values.Set("offset", fmt.Sprintf("%d", offset))
	}
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, t.apiURL("getUpdates")+"?"+values.Encode(), nil)
	if err != nil {
		return nil, err
	}
	resp, err := t.client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	var out tgResponse[[]TGUpdate]
	if err := json.NewDecoder(resp.Body).Decode(&out); err != nil {
		return nil, err
	}
	if !out.OK {
		return nil, errors.New(out.Description)
	}
	return out.Result, nil
}

func (t *Telegram) apiURL(method string) string {
	return "https://api.telegram.org/bot" + t.token + "/" + method
}

func (u TGUser) FullName() string {
	name := strings.TrimSpace(strings.TrimSpace(u.FirstName) + " " + strings.TrimSpace(u.LastName))
	if name != "" {
		return name
	}
	if u.Username != "" {
		return u.Username
	}
	return fmt.Sprintf("user_%d", u.ID)
}