use imap::types::Fetch;
use imap::Session;
use mailparse::parse_mail;
use native_tls::TlsConnector;
use reqwest::blocking::Client;
use rusqlite::{params, Connection};
use serde::{Deserialize};
use std::net::TcpStream;
use clap::Parser;
use mailparse::MailHeaderMap;
use regex::Regex;

#[derive(Parser)]
#[command(name = "openproject-sync", version, about = "Migrates E-Mails to OpenProject tasks")]
struct Args {
    #[arg(short, long, default_value = "config.json")]
    config: String,
}

#[derive(Debug, Deserialize)]
struct Config {
    imap_server: String,
    imap_user: String,
    imap_pass: String,
    openproject_url: String,
    openproject_key: String,
    openproject_project_id: u64,
    map_mail_ticket: String,
    target_email: String,
    mailbox_tickets: String,
    mailboxes: Vec<String>,
}

#[derive(Debug)]
struct Email {
    message_id: String,
    in_reply_to: Option<String>,
    subject: String,
    body: String,
    to: String,
    cc: String,
}

fn load_config(path: &str) -> Config {
    let text = std::fs::read_to_string(path).expect("ERROR: Config not found");
    serde_json::from_str(&text).expect("ERROR: Invalid config")
}

fn connect_imap(cfg: &Config) -> Session<native_tls::TlsStream<TcpStream>> {
    let tls = TlsConnector::builder().build().unwrap();
    let client = imap::connect((&cfg.imap_server[..], 993), &cfg.imap_server, &tls).unwrap();
    client.login(&cfg.imap_user, &cfg.imap_pass).map_err(|e| e.0).unwrap()
}

fn parse_email(fetch: &Fetch) -> Option<Email> {
    let body = fetch.body()?;
    let raw_str = std::str::from_utf8(body).ok()?.to_string();
    let parsed = parse_mail(body).ok()?;
    let headers = parsed.get_headers();

    let message_id = headers.get_first_value("Message-ID")?;
    let subject = headers.get_first_value("Subject").unwrap_or_else(|| "(no subject)".into());
    let in_reply_to = headers.get_first_value("In-Reply-To");
    let to = headers.get_first_value("To").unwrap_or_default();
    let cc = headers.get_first_value("Cc").unwrap_or_default();

    let mut body_text = String::new();

    if parsed.subparts.is_empty() {
        body_text = parsed.get_body().ok()?;
    } else {
        for part in &parsed.subparts {
            let content_type = part.ctype.mimetype.to_lowercase();
            match content_type.as_str() {
                "text/plain" => {
                    body_text = part.get_body().ok()?;
                    break;
                }
                "text/html" if body_text.is_empty() => {
                    body_text = part.get_body().ok()?;
                }
                "text/calendar" if body_text.is_empty() => {
                    body_text = part.get_body().ok()?;
                }
                _ => {}
            }
        }
    }

    if body_text.trim().is_empty() {
        println!("WARNING: No body for E-Mail '{}'", subject);
    }

    let mut filtered_raw = String::new();
    let mut in_attachment = false;
    let mut current_part_header = String::new();

    for line in raw_str.lines() {
        if line.starts_with("--") {
            in_attachment = false;
            current_part_header.clear();
            filtered_raw.push_str(line);
            filtered_raw.push('\n');
            continue;
        }

        if line.to_lowercase().starts_with("content-type:") {
            current_part_header = line.to_lowercase();

            if current_part_header.contains("application/")
                || current_part_header.contains("image/")
                || current_part_header.contains("audio/")
                || current_part_header.contains("octet-stream")
            {
                in_attachment = true;

                let filename = if line.to_lowercase().contains("name=") {
                    line.split("name=").nth(1).unwrap_or("").trim_matches('"')
                } else {
                    ""
                };

                let notice = format!(
                    "[Attachment stripped: {}; filename=\"{}\"]\n",
                    current_part_header.trim(),
                    filename
                );
                filtered_raw.push_str(&notice);
            } else {
                filtered_raw.push_str(line);
                filtered_raw.push('\n');
            }
        } else if !in_attachment {
            filtered_raw.push_str(line);
            filtered_raw.push('\n');
        }
    }

    let body_full = format!(
        "{}\n\n<details>\n<summary>Show source code</summary>\n\n```\n{}\n```\n</details>",
        body_text.trim(),
        filtered_raw.trim()
    );

    Some(Email {
        message_id,
        in_reply_to,
        subject,
        body: body_full,
        to: to,
        cc: cc,
    })
}

fn init_db(path: &str) -> Connection {
    let conn = Connection::open(path).unwrap();
    conn.execute(
        "CREATE TABLE IF NOT EXISTS message_map (
            message_id TEXT PRIMARY KEY,
            task_id INTEGER
        )",
        [],
    ).unwrap();
    conn
}

fn is_processed(conn: &Connection, msg_id: &str) -> bool {
    conn.query_row(
        "SELECT EXISTS(SELECT 1 FROM message_map WHERE message_id = ?)",
        [msg_id],
        |row| row.get(0),
    ).unwrap_or(false)
}

fn save_mapping(conn: &Connection, msg_id: &str, task_id: u64) {
    conn.execute(
        "INSERT OR IGNORE INTO message_map (message_id, task_id) VALUES (?, ?)",
        params![msg_id, task_id],
    ).unwrap();
}

fn get_task_for_message(conn: &Connection, msg_id: &str) -> Option<u64> {
    conn.query_row(
        "SELECT task_id FROM message_map WHERE message_id = ?",
        [msg_id],
        |row| row.get(0),
    ).ok()
}

fn create_task(client: &Client, email: &Email, cfg: &Config) -> u64 {
    let url = format!("{}/api/v3/work_packages", cfg.openproject_url);
    let resp = client.post(&url)
        .basic_auth("apikey", Some(&cfg.openproject_key))
        .json(&serde_json::json!({
            "subject": format!("E-Mail: {}", email.subject),
            "description": {
                "format": "markdown",
                "raw": email.body
            },
            "scheduleManually": false,
            "ignoreNonWorkingDays": false,
            "_links": {
                "type": {
                    "href": "/api/v3/types/1",
                    "title": "Task"
                },
                "priority": {
                    "href": "/api/v3/priorities/8",
                    "title": "Normal"
                },
                "project": {
                    "href": format!("/api/v3/projects/{}", cfg.openproject_project_id)
                },
                "status": {
                    "href": "/api/v3/statuses/1",
                    "title": "New"
                },
                "assignee": {
                    "href": null
                },
                "responsible": {
                    "href": null
                },
                "category": {
                    "href": null
                },
                "version": {
                    "href": null
                },
                "parent": {
                    "href": null
                }
            }
        }))
        .send()
        .expect("ERROR: Creating task failed");
    let json: serde_json::Value = resp.json().unwrap();
    //eprintln!("INFO: OpenProject API answer:\n{}", serde_json::to_string_pretty(&json).unwrap());
    json["id"].as_u64().unwrap()
}

fn add_comment(client: &Client, task_id: u64, email: &Email, cfg: &Config) {
    let url = format!("{}/api/v3/work_packages/{}/activities", cfg.openproject_url, task_id);
    client.post(&url)
        .basic_auth("apikey", Some(&cfg.openproject_key))
        .json(&serde_json::json!({
            "comment": { "raw": email.body }
        }))
        .send()
        .expect("ERROR: Adding comment failed");
}

fn move_email_by_uid(session: &mut Session<native_tls::TlsStream<TcpStream>>, source_folder: &str, target_folder: &str, uid: u32) {
    session.select(source_folder).expect("ERROR: Unable to open folder to move by uid");

    let uid_str = uid.to_string();
    session.uid_copy(&uid_str, target_folder).expect("ERROR: Unable to copy message");
    session.uid_store(&uid_str, "+FLAGS.SILENT (\\Deleted)").expect("ERROR: Unable to mark message as deleted");
    session.expunge().expect("ERROR: Unable to delete message");
}

fn process_mailbox(session: &mut Session<native_tls::TlsStream<TcpStream>>, mbox: &str, client: &Client, conn: &Connection, cfg: &Config, email_regex: &Regex) {
    session.select(mbox).unwrap();
    let msgs = session.uid_fetch("1:*", "RFC822").unwrap();
    println!("INFO: Found messages: {}", msgs.len());

    for msg in msgs.iter() {
        let uid = match msg.uid {
            Some(uid) => uid,
            None => {
                println!("WARNING: No UID, skipping message");
                continue;
            }
        };
    
        if let Some(email) = parse_email(msg) {
            if is_processed(conn, &email.message_id) {
                println!("INFO: Message already merged: {}", email.subject);
            } else {
                println!("INFO: New message: {}", email.subject);
                let task_id = match email.in_reply_to.as_deref() {
                    Some(parent_id) => {
                        if let Some(existing_id) = get_task_for_message(conn, parent_id) {
                            println!("INFO: Adding comment to task #{}", existing_id);
                            add_comment(client, existing_id, &email, cfg);
                            existing_id
                        } else {
                            println!("INFO: Creating new task (answer without original message)");
                            create_task(client, &email, cfg)
                        }
                    }
                    None => {
                        if !(email_regex.is_match(&email.to) || email_regex.is_match(&email.cc)) {
                            println!("INFO: Ignoring unknown e-mail recipient");
                            continue;
                        }
                        println!("INFO: Creating new task");
                        create_task(client, &email, cfg)
                    }
                };
    
                println!("INFO: Mapping: {} -> Task #{}", email.message_id, task_id);
                save_mapping(conn, &email.message_id, task_id);
            }
    
            move_email_by_uid(session, mbox, &cfg.mailbox_tickets, uid);
        }
    }    
}

fn main() {
    env_logger::init();
    let args = Args::parse();
    println!("INFO: Loading config: {}", args.config);
    let cfg = load_config(&args.config);

    let email_pattern = format!(r"(?i)\b{}\b", regex::escape(&cfg.target_email));
    let email_regex = Regex::new(&email_pattern).expect("ERROR: Invalid target e-mail");

    println!("INFO: Initializing OpenProject connection: {}", cfg.openproject_url);
    let client = Client::new();

    println!("INFO: Inititalizing SQLite database: {}", cfg.map_mail_ticket);
    let conn = init_db(&cfg.map_mail_ticket);

    println!("INFO: Connecting to IMAP server: {}", cfg.imap_server);
    let mut session = connect_imap(&cfg);

    for folder in &cfg.mailboxes {
        println!("INFO: Processing folder: {}", folder);
        process_mailbox(&mut session, folder, &client, &conn, &cfg, &email_regex);
    }

    println!("INFO: Disconnecting from IMAP server");
    session.logout().unwrap();

    println!("INFO: Sync completed");
}