//! Doodstream.com uploader. Port of `lib/doodstream-upload.js`.
//!
//! Flow (simplified — no OTP path in this revision):
//! 1. POST /            op=login_ajax&login=…&password=…   → sets session cookies
//! 2. GET  /?op=upload                                     → scrape `sess_id` from HTML
//! 3. GET  /?op=upload_server                              → { result: "https://srv/upload/01" }
//! 4. POST <server>                                        → multipart sess_id+utype=reg+file
//! 5. Response may be JSON or a filecode-bearing HTML; extract filecode.

use super::{UploadCtx, UploadTask};
use crate::error::{AppError, AppResult};
use crate::events::UploadResult;

use bytes::Bytes;
use once_cell::sync::Lazy;
use regex::Regex;
use reqwest::{multipart, Body, Client};
use std::time::Duration;
use tokio::fs::File;
use tokio_util::io::ReaderStream;

const BASE_URL: &str = "https://doodstream.com";
const UA: &str = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36";

fn build_client() -> AppResult<Client> {
    Client::builder()
        .timeout(Duration::from_secs(30 * 60))
        .connect_timeout(Duration::from_secs(60))
        .cookie_store(true)
        .redirect(reqwest::redirect::Policy::limited(10))
        .gzip(true)
        .user_agent(UA)
        .build()
        .map_err(AppError::from)
}

pub async fn upload(task: UploadTask, ctx: UploadCtx) -> AppResult<UploadResult> {
    if task.username.is_empty() || task.password.is_empty() {
        return Err(AppError::BadCredentials);
    }
    let c = build_client()?;

    // --- Login ---
    let _ = c.get(BASE_URL).send().await; // warm up

    let login_body = serde_urlencoded::to_string([
        ("op", "login_ajax"),
        ("login", task.username.as_str()),
        ("password", task.password.as_str()),
        ("loginotp", ""),
    ]).unwrap_or_default();

    let res = c.post(format!("{BASE_URL}/"))
        .header("Content-Type", "application/x-www-form-urlencoded")
        .header("Referer", format!("{BASE_URL}/"))
        .header("X-Requested-With", "XMLHttpRequest")
        .body(login_body)
        .send()
        .await?;
    let status = res.status();
    let body = res.text().await.unwrap_or_default();

    // Redirect response (3xx auto-followed by client) or dashboard hit → login OK.
    // Otherwise try JSON shape.
    if !body.contains("Dashboard") {
        if let Ok(v) = serde_json::from_str::<serde_json::Value>(&body) {
            if let Some(s) = v.get("status").and_then(|x| x.as_str()) {
                if s == "fail" {
                    let msg = v.get("message").and_then(|x| x.as_str()).unwrap_or("Login fehlgeschlagen");
                    if msg.to_lowercase().contains("otp") {
                        return Err(AppError::Other(format!("Doodstream: OTP erforderlich ({msg}) — OTP-Login in 2.0 POC noch nicht implementiert")));
                    }
                    return Err(AppError::BadCredentials);
                }
            }
        } else if !status.is_redirection() && !status.is_success() {
            return Err(AppError::BadCredentials);
        }
    }

    // --- Extract sess_id from /?op=upload ---
    let upload_page = c.get(format!("{BASE_URL}/?op=upload"))
        .header("Referer", format!("{BASE_URL}/")).send().await?
        .text().await.unwrap_or_default();
    let sess_id = extract_sess_id(&upload_page)
        .ok_or_else(|| AppError::BadResponse("Doodstream: sess_id nicht gefunden".into()))?;

    // --- Get upload server ---
    let srv_json = c.get(format!("{BASE_URL}/?op=upload_server"))
        .header("Referer", format!("{BASE_URL}/?op=upload")).send().await?
        .text().await.unwrap_or_default();
    let server_url = match serde_json::from_str::<serde_json::Value>(&srv_json) {
        Ok(v) => v.get("result").and_then(|x| x.as_str()).map(|s| s.to_string()),
        Err(_) => None,
    }.or_else(|| SRV_RE.captures(&upload_page).and_then(|c| c.get(1).map(|m| m.as_str().to_string())))
      .ok_or_else(|| AppError::BadResponse("Doodstream: Upload-Server nicht erhalten".into()))?;

    // --- POST multipart ---
    let path = task.file_path.as_path();
    let file_name = path.file_name().unwrap_or_default().to_string_lossy().to_string();
    let file_size = tokio::fs::metadata(path).await?.len();
    let file = File::open(path).await?;
    let stream = progress_stream(file, file_size, ctx.clone());
    let part = multipart::Part::stream_with_length(Body::wrap_stream(stream), file_size)
        .file_name(file_name.clone())
        .mime_str("application/octet-stream")
        .map_err(|e| AppError::Other(format!("MIME: {e}")))?;
    let form = multipart::Form::new()
        .text("sess_id", sess_id)
        .text("utype", "reg")
        .part("file", part);

    let up = c.post(&server_url)
        .header("Referer", format!("{BASE_URL}/?op=upload"))
        .multipart(form)
        .send().await?;
    let up_status = up.status();
    let raw = up.text().await.unwrap_or_default();

    if up_status.is_client_error() || up_status.is_server_error() {
        return Err(AppError::HosterError("Doodstream".into(),
            format!("Upload HTTP {}: {}", up_status.as_u16(), &raw[..raw.len().min(200)])));
    }

    parse_upload_response(&raw, &file_name, &c).await
}

static SESS_RE_INPUT: Lazy<Regex> = Lazy::new(||
    Regex::new(r#"name=["']sess_id["'][^>]*value=["']([a-zA-Z0-9]+)["']"#).unwrap());
static SESS_RE_VUE: Lazy<Regex> = Lazy::new(||
    Regex::new(r#"sess_id['"\s:]+['"]([a-zA-Z0-9]+)['"]"#).unwrap());
static SRV_RE: Lazy<Regex> = Lazy::new(||
    Regex::new(r#"srv_url['"\s:]+['"]?(https?://[^'">\s]+)"#).unwrap());
static FN_RE: Lazy<Regex> = Lazy::new(||
    Regex::new(r#"name=["']fn["'][^>]*value=["']([a-zA-Z0-9]+)["']"#).unwrap());
static DL_RE: Lazy<Regex> = Lazy::new(||
    Regex::new(r#"https?://[a-z0-9.]+/d/([a-zA-Z0-9]+)"#).unwrap());

fn extract_sess_id(html: &str) -> Option<String> {
    SESS_RE_INPUT.captures(html).or_else(|| SESS_RE_VUE.captures(html))
        .and_then(|c| c.get(1).map(|m| m.as_str().to_string()))
}

async fn parse_upload_response(raw: &str, _file_name: &str, client: &Client) -> AppResult<UploadResult> {
    // JSON shape?
    if let Ok(v) = serde_json::from_str::<serde_json::Value>(raw) {
        if let Some(code) = v.get("file_code").and_then(|x| x.as_str())
            .or_else(|| v.pointer("/files/0/filecode").and_then(|x| x.as_str()))
            .or_else(|| v.pointer("/result/0/filecode").and_then(|x| x.as_str()))
        {
            if !code.is_empty() {
                return Ok(build_result(code));
            }
        }
    }

    // XFS-style: hidden input name="fn" holds the filecode. Submit op=upload_result
    // to complete, then parse the follow-up for download URL.
    if let Some(cap) = FN_RE.captures(raw) {
        let fn_code = cap.get(1).unwrap().as_str();
        // Submit upload_result
        let body = serde_urlencoded::to_string([
            ("op", "upload_result"),
            ("fn", fn_code),
        ]).unwrap_or_default();
        if let Ok(follow) = client.post(format!("{BASE_URL}/"))
            .header("Content-Type", "application/x-www-form-urlencoded")
            .header("Referer", format!("{BASE_URL}/"))
            .body(body).send().await
        {
            let follow_text = follow.text().await.unwrap_or_default();
            if let Some(c) = DL_RE.captures(&follow_text) {
                if let Some(m) = c.get(1) { return Ok(build_result(m.as_str())); }
            }
        }
        if fn_code.len() >= 8 { return Ok(build_result(fn_code)); }
    }

    if let Some(c) = DL_RE.captures(raw) {
        if let Some(m) = c.get(1) { return Ok(build_result(m.as_str())); }
    }

    Err(AppError::BadResponse(format!(
        "Doodstream: Upload-Antwort ohne filecode ({}))",
        &raw[..raw.len().min(240)]
    )))
}

fn build_result(code: &str) -> UploadResult {
    UploadResult {
        download_url: Some(format!("https://dsvplay.com/d/{code}")),
        embed_url: Some(format!("https://dsvplay.com/e/{code}")),
        file_code: Some(code.to_string()),
    }
}

fn progress_stream(
    file: File,
    total: u64,
    ctx: UploadCtx,
) -> impl futures::Stream<Item = Result<Bytes, std::io::Error>> + Send + 'static {
    use futures::StreamExt;
    let ctx1 = ctx.clone();
    let ctx2 = ctx;
    let mut acc: u64 = 0;
    ReaderStream::with_capacity(file, 256 * 1024).then(move |chunk| {
        let ctx_in = ctx1.clone();
        let ctx_pr = ctx2.clone();
        async move {
            match chunk {
                Ok(b) => {
                    if ctx_in.is_aborted() {
                        return Err(std::io::Error::new(std::io::ErrorKind::Other, "Aborted"));
                    }
                    ctx_in.throttle(b.len() as u64).await;
                    acc += b.len() as u64;
                    (ctx_pr.on_progress)(acc, total);
                    Ok(b)
                }
                Err(e) => Err(e),
            }
        }
    })
}