package telegram

import (
	"io"
	"log/slog"
	"net/http"
	"time"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/channel/adapter"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/logger"
)

// Defaults and knob values for the Telegram Bot API integration.
const (
	// defaultBaseURL is the Telegram API root for unconfigured adapters.
	defaultBaseURL = "https://api.telegram.org"
	// httpTimeout bounds a single Bot API request.
	httpTimeout = 180 * time.Second
	// longPollTimeoutSec is the getUpdates long-poll timeout in seconds.
	longPollTimeoutSec = 50
	// pollInterval is how long to sleep between getUpdates batches.
	pollInterval = 1 * time.Second
	// maxUpdatesPerPoll caps the number of updates fetched in one getUpdates call.
	maxUpdatesPerPoll = 100
	// maxMessageLen is Telegram's per-message text limit.
	maxMessageLen = 4096
)

// Config holds the settings required to reach the Telegram Bot API.
type Config struct {
	// BotToken is the secret token issued by BotFather. It is stored and
	// surfaced through Config() but never written to logs.
	BotToken string `json:"bot_token"`
	// WebhookURL is the public HTTPS endpoint Telegram delivers updates to.
	// When empty the adapter uses getUpdates long polling instead.
	WebhookURL string `json:"webhook_url"`
}

// Option customizes an Adapter at construction time.
type Option func(*Adapter)

// WithHTTPClient injects the *http.Client used for Bot API requests. Tests pass
// the client of an httptest.Server so the mock endpoint answers calls.
func WithHTTPClient(c *http.Client) Option {
	return func(a *Adapter) { a.client = c }
}

// WithBaseURL overrides the Telegram API root (default https://api.telegram.org).
// Tests point it at an httptest.Server URL.
func WithBaseURL(base string) Option {
	return func(a *Adapter) {
		if base != "" {
			a.baseURL = base
		}
	}
}

// WithLogger injects the logger used by the adapter. When nil the adapter logs
// through a discard logger so a bare adapter stays silent; callers wire their
// production logger via this option.
func WithLogger(l *slog.Logger) Option {
	return func(a *Adapter) {
		if l == nil {
			l = logger.New(logger.Options{Out: io.Discard})
		}
		a.log = logger.WithSource(l, "plugins/channels/telegram")
	}
}

// New builds a Telegram adapter. It performs no network I/O; call Connect to
// establish the session.
func New(cfg Config, opts ...Option) *Adapter {
	a := &Adapter{
		cfg:     cfg,
		client:  &http.Client{Timeout: httpTimeout},
		baseURL: defaultBaseURL,
		log:     logger.WithSource(logger.New(logger.Options{Out: io.Discard}), "plugins/channels/telegram"),
		chats:   map[string]adapter.ChannelInfo{},
	}
	for _, opt := range opts {
		opt(a)
	}
	return a
}

// endpoint returns the absolute Bot API URL for the given method, bundling the
// token into the path (never into query parameters or logs).
func (a *Adapter) endpoint(method string) string {
	return a.baseURL + "/bot" + a.cfg.BotToken + "/" + method
}