// Telegram module.
//
// Long-polls the Telegram Bot API for messages from Kent's chat.
// Downloads media (photos, voice, documents) to local files.
// Sends text and files. Notifications flow through mpsc into the
// daemon's main state.
//
// Only accepts messages from the configured chat_id (prompt
// injection defense — other senders get a "private bot" reply).

use crate::config::{Config, TelegramConfig};
use crate::notify::Notification;
use crate::{home, now};
use std::cell::RefCell;
use std::collections::VecDeque;
use std::path::PathBuf;
use std::rc::Rc;
use tokio::sync::mpsc;
use tracing::{error, info};

const MAX_LOG_LINES: usize = 100;
const POLL_TIMEOUT: u64 = 30;

pub struct TelegramState {
    pub config: TelegramConfig,
    pub connected: bool,
    pub log: VecDeque<String>,
    pub last_offset: i64,
    client: reqwest::Client,
}

pub type SharedTelegram = Rc<RefCell<TelegramState>>;

impl TelegramState {
    fn new(config: TelegramConfig) -> Self {
        let last_offset = load_offset();
        Self {
            config,
            connected: false,
            log: VecDeque::with_capacity(MAX_LOG_LINES),
            last_offset,
            client: reqwest::Client::new(),
        }
    }

    fn push_log(&mut self, line: &str) {
        if self.log.len() >= MAX_LOG_LINES {
            self.log.pop_front();
        }
        self.log.push_back(line.to_string());
    }

    fn api_url(&self, method: &str) -> String {
        format!(
            "https://api.telegram.org/bot{}/{}",
            self.config.token, method
        )
    }
}

fn offset_path() -> PathBuf {
    home().join(".claude/telegram/last_offset")
}

fn load_offset() -> i64 {
    std::fs::read_to_string(offset_path())
        .ok()
        .and_then(|s| s.trim().parse().ok())
        .unwrap_or(0)
}

fn save_offset(offset: i64) {
    let _ = std::fs::write(offset_path(), offset.to_string());
}

fn history_path() -> PathBuf {
    home().join(".claude/telegram/history.log")
}

fn media_dir() -> PathBuf {
    home().join(".claude/telegram/media")
}

fn append_history(line: &str) {
    use std::io::Write;
    if let Ok(mut f) = std::fs::OpenOptions::new()
        .create(true)
        .append(true)
        .open(history_path())
    {
        let _ = writeln!(f, "{}", line);
    }
}

/// Start the Telegram module. Returns the shared state handle.
pub fn start(
    config: TelegramConfig,
    notify_tx: mpsc::UnboundedSender<Notification>,
    _daemon_config: Rc<RefCell<Config>>,
) -> SharedTelegram {
    let state = Rc::new(RefCell::new(TelegramState::new(config)));
    let state_clone = state.clone();

    tokio::task::spawn_local(async move {
        poll_loop(state_clone, notify_tx).await;
    });

    state
}

async fn poll_loop(
    state: SharedTelegram,
    notify_tx: mpsc::UnboundedSender<Notification>,
) {
    let _ = std::fs::create_dir_all(media_dir());

    loop {
        match poll_once(&state, &notify_tx).await {
            Ok(()) => {}
            Err(e) => {
                error!("telegram: poll error: {e}");
                tokio::time::sleep(std::time::Duration::from_secs(5)).await;
            }
        }
    }
}

async fn poll_once(
    state: &SharedTelegram,
    notify_tx: &mpsc::UnboundedSender<Notification>,
) -> Result<(), Box<dyn std::error::Error>> {
    let (url, chat_id, token) = {
        let s = state.borrow();
        let url = format!(
            "{}?offset={}&timeout={}",
            s.api_url("getUpdates"),
            s.last_offset,
            POLL_TIMEOUT,
        );
        (url, s.config.chat_id, s.config.token.clone())
    };

    let client = state.borrow().client.clone();
    let resp: serde_json::Value = client
        .get(&url)
        .timeout(std::time::Duration::from_secs(POLL_TIMEOUT + 5))
        .send()
        .await?
        .json()
        .await?;

    if !state.borrow().connected {
        state.borrow_mut().connected = true;
        info!("telegram: connected");
    }

    let results = resp["result"].as_array();
    let results = match results {
        Some(r) => r,
        None => return Ok(()),
    };

    for update in results {
        let update_id = update["update_id"].as_i64().unwrap_or(0);
        let msg = &update["message"];

        // Update offset
        {
            let mut s = state.borrow_mut();
            s.last_offset = update_id + 1;
            save_offset(s.last_offset);
        }

        let msg_chat_id = msg["chat"]["id"].as_i64().unwrap_or(0);
        if msg_chat_id != chat_id {
            // Reject messages from unknown chats
            let reject_url = format!(
                "https://api.telegram.org/bot{}/sendMessage",
                token
            );
            let _ = client
                .post(&reject_url)
                .form(&[
                    ("chat_id", msg_chat_id.to_string()),
                    ("text", "This is a private bot.".to_string()),
                ])
                .send()
                .await;
            continue;
        }

        let sender = msg["from"]["first_name"]
            .as_str()
            .unwrap_or("unknown")
            .to_string();

        // Handle different message types
        if let Some(text) = msg["text"].as_str() {
            let log_line = format!("[{}] {}", sender, text);
            state.borrow_mut().push_log(&log_line);

            let ts = timestamp();
            append_history(&format!("{ts} [{sender}] {text}"));

            let _ = notify_tx.send(Notification {
                ntype: format!("telegram.{}", sender.to_lowercase()),
                urgency: crate::notify::NORMAL,
                message: log_line,
                timestamp: now(),
            });
        } else if let Some(photos) = msg["photo"].as_array() {
            // Pick largest photo
            let best = photos.iter().max_by_key(|p| p["file_size"].as_i64().unwrap_or(0));
            if let Some(photo) = best {
                if let Some(file_id) = photo["file_id"].as_str() {
                    let caption = msg["caption"].as_str().unwrap_or("");
                    let local = download_file(&client, &token, file_id, ".jpg").await;
                    let display = match &local {
                        Some(p) => format!("[photo: {}]{}", p.display(), if caption.is_empty() { String::new() } else { format!(" {caption}") }),
                        None => format!("[photo]{}", if caption.is_empty() { String::new() } else { format!(" {caption}") }),
                    };
                    let log_line = format!("[{}] {}", sender, display);
                    state.borrow_mut().push_log(&log_line);
                    let ts = timestamp();
                    append_history(&format!("{ts} [{sender}] {display}"));

                    let _ = notify_tx.send(Notification {
                        ntype: format!("telegram.{}", sender.to_lowercase()),
                        urgency: crate::notify::NORMAL,
                        message: log_line,
                        timestamp: now(),
                    });
                }
            }
        } else if msg["voice"].is_object() {
            if let Some(file_id) = msg["voice"]["file_id"].as_str() {
                let caption = msg["caption"].as_str().unwrap_or("");
                let local = download_file(&client, &token, file_id, ".ogg").await;
                let display = match &local {
                    Some(p) => format!("[voice: {}]{}", p.display(), if caption.is_empty() { String::new() } else { format!(" {caption}") }),
                    None => format!("[voice]{}", if caption.is_empty() { String::new() } else { format!(" {caption}") }),
                };
                let log_line = format!("[{}] {}", sender, display);
                state.borrow_mut().push_log(&log_line);
                let ts = timestamp();
                append_history(&format!("{ts} [{sender}] {display}"));

                let _ = notify_tx.send(Notification {
                    ntype: format!("telegram.{}", sender.to_lowercase()),
                    urgency: crate::notify::NORMAL,
                    message: log_line,
                    timestamp: now(),
                });
            }
        } else if msg["document"].is_object() {
            if let Some(file_id) = msg["document"]["file_id"].as_str() {
                let fname = msg["document"]["file_name"].as_str().unwrap_or("file");
                let caption = msg["caption"].as_str().unwrap_or("");
                let local = download_file(&client, &token, file_id, "").await;
                let display = match &local {
                    Some(p) => format!("[doc: {} -> {}]{}", fname, p.display(), if caption.is_empty() { String::new() } else { format!(" {caption}") }),
                    None => format!("[doc: {}]{}", fname, if caption.is_empty() { String::new() } else { format!(" {caption}") }),
                };
                let log_line = format!("[{}] {}", sender, display);
                state.borrow_mut().push_log(&log_line);
                let ts = timestamp();
                append_history(&format!("{ts} [{sender}] {display}"));

                let _ = notify_tx.send(Notification {
                    ntype: format!("telegram.{}", sender.to_lowercase()),
                    urgency: crate::notify::NORMAL,
                    message: log_line,
                    timestamp: now(),
                });
            }
        }
    }

    Ok(())
}

async fn download_file(
    client: &reqwest::Client,
    token: &str,
    file_id: &str,
    ext: &str,
) -> Option<PathBuf> {
    let url = format!("https://api.telegram.org/bot{token}/getFile?file_id={file_id}");
    let resp: serde_json::Value = client.get(&url).send().await.ok()?.json().await.ok()?;
    let file_path = resp["result"]["file_path"].as_str()?;

    let download_url = format!("https://api.telegram.org/file/bot{token}/{file_path}");
    let bytes = client.get(&download_url).send().await.ok()?.bytes().await.ok()?;

    let basename = std::path::Path::new(file_path)
        .file_name()
        .and_then(|n| n.to_str())
        .unwrap_or("file");
    let local_name = if ext.is_empty() {
        basename.to_string()
    } else {
        let stem = std::path::Path::new(basename)
            .file_stem()
            .and_then(|s| s.to_str())
            .unwrap_or("file");
        format!("{}{}", stem, ext)
    };
    let secs = now() as u64;
    let local_path = media_dir().join(format!("{secs}_{local_name}"));
    std::fs::write(&local_path, &bytes).ok()?;
    Some(local_path)
}

fn timestamp() -> String {
    // Use the same unix seconds approach as IRC module
    format!("{}", now() as u64)
}

/// Handle a runtime command from RPC.
pub async fn handle_command(
    state: &SharedTelegram,
    _daemon_config: &Rc<RefCell<Config>>,
    cmd: &str,
    args: &[String],
) -> Result<String, String> {
    match cmd {
        "send" => {
            let msg = args.join(" ");
            if msg.is_empty() {
                return Err("usage: telegram send <message>".into());
            }
            let (url, client) = {
                let s = state.borrow();
                (s.api_url("sendMessage"), s.client.clone())
            };
            let chat_id = state.borrow().config.chat_id.to_string();
            client
                .post(&url)
                .form(&[("chat_id", chat_id.as_str()), ("text", msg.as_str())])
                .send()
                .await
                .map_err(|e| e.to_string())?;

            let ts = timestamp();
            append_history(&format!("{ts} [ProofOfConcept] {msg}"));

            Ok("sent".to_string())
        }
        "status" => {
            let s = state.borrow();
            Ok(format!(
                "connected={} log_lines={} offset={}",
                s.connected,
                s.log.len(),
                s.last_offset,
            ))
        }
        "log" => {
            let n: usize = args
                .first()
                .and_then(|s| s.parse().ok())
                .unwrap_or(15);
            let s = state.borrow();
            let lines: Vec<&String> = s.log.iter().rev().take(n).collect();
            let mut lines: Vec<&str> = lines.iter().map(|s| s.as_str()).collect();
            lines.reverse();
            Ok(lines.join("\n"))
        }
        _ => Err(format!(
            "unknown telegram command: {cmd}\n\
             commands: send, status, log"
        )),
    }
}