//! Byse.sx uploader. Port of the generic XFS flow in `lib/hosters.js`.
//!
//! Steps:
//! 1. GET  https://api.byse.sx/upload/server?key=API_KEY         → { result: "https://srv.../upload.cgi" }
//! 2. Snapshot file list so we can identify the new upload even if filecode
//!    comes back empty (Byse sometimes replies with msg=OK + filecode="" but
//!    the file lands on the server anyway and gets its code async).
//! 3. POST multipart to the returned server with form field `key=API_KEY`.
//! 4. Parse JSON → if files[0].filecode is set, done. Otherwise poll file list
//!    up to 30s for a new filecode that matches the uploaded filename.

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

use bytes::Bytes;
use reqwest::{multipart, Body, Client};
use serde::Deserialize;
use std::path::Path;
use std::time::Duration;
use tokio::fs::File;
use tokio_util::io::ReaderStream;

const API_BASE: &str = "https://api.byse.sx";
const DOWNLOAD_BASE: &str = "https://byse.sx";

fn client() -> AppResult<Client> {
    Client::builder()
        .timeout(Duration::from_secs(30 * 60))
        .connect_timeout(Duration::from_secs(60))
        .pool_max_idle_per_host(20)
        .gzip(true)
        .user_agent("multi-hoster-uploader/2.0")
        .build()
        .map_err(AppError::from)
}

pub async fn upload(task: UploadTask, ctx: UploadCtx) -> AppResult<UploadResult> {
    let key = task.api_key.trim();
    if key.is_empty() { return Err(AppError::BadCredentials); }
    let path = task.file_path.as_path();
    let meta = tokio::fs::metadata(path).await?;
    let file_size = meta.len();

    let c = client()?;

    // Baseline: which file_codes does the account already have?
    let baseline = fetch_file_list(&c, key).await.unwrap_or_default();
    let baseline_set: std::collections::HashSet<String> =
        baseline.iter().map(|f| f.file_code.clone()).collect();

    // Get upload server URL.
    let server_url = get_upload_server(&c, key).await?;

    // POST multipart.
    let file_name = path.file_name().unwrap_or_default().to_string_lossy().to_string();
    let upload_url = append_query(&server_url, "key", key);

    let file = File::open(path).await?;
    let stream = progress_stream(file, file_size, ctx.clone());
    let body = Body::wrap_stream(stream);
    let part = multipart::Part::stream_with_length(body, 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("key", key.to_string())
        .part("file", part);

    let resp = c.post(&upload_url)
        .header("Accept", "application/json, text/plain;q=0.9, */*;q=0.8")
        .multipart(form)
        .send()
        .await?;

    let status = resp.status();
    let raw = resp.text().await.unwrap_or_default();

    if !status.is_success() {
        // Network/CDN level failure — surface raw.
        let snippet = raw.chars().take(240).collect::<String>();
        return Err(AppError::HosterError(
            "Byse".into(),
            format!("Upload fehlgeschlagen (HTTP {}): {}", status.as_u16(), snippet),
        ));
    }

    let payload: ByseResp = serde_json::from_str(&raw)
        .map_err(|_| AppError::BadResponse(format!("Byse: Antwort war kein JSON: {}", &raw[..raw.len().min(240)])))?;

    // Normal success: files[0].filecode present.
    if let Some(f) = payload.files.as_ref().and_then(|v| v.first()) {
        let code = f.filecode.clone().or(f.file_code.clone()).unwrap_or_default();
        if !code.is_empty() {
            return Ok(UploadResult {
                download_url: Some(format!("{DOWNLOAD_BASE}/d/{code}")),
                embed_url: Some(format!("{DOWNLOAD_BASE}/e/{code}")),
                file_code: Some(code),
            });
        }
        // Per-file rejection (e.g. "Not video file format") → but we've seen
        // the file land anyway. Poll before giving up.
        if let Some(s) = &f.status {
            if !is_ok_ish(s) {
                tracing::warn!("Byse per-file status `{s}` — polling file list to confirm");
            }
        }
    }

    // Poll /api/file/list for the uploaded filename.
    if let Some(found) = poll_for_upload(&c, key, &file_name, &baseline_set, &ctx).await {
        return Ok(UploadResult {
            download_url: Some(format!("{DOWNLOAD_BASE}/d/{}", found)),
            embed_url: Some(format!("{DOWNLOAD_BASE}/e/{}", found)),
            file_code: Some(found),
        });
    }

    // Nothing landed on the account. If server reported a per-file status,
    // surface that as the error; else a generic one.
    let err_msg = payload
        .files
        .as_ref()
        .and_then(|v| v.first())
        .and_then(|f| f.status.clone())
        .filter(|s| !is_ok_ish(s))
        .map(|s| format!("Byse lehnte Datei ab: {s}"))
        .unwrap_or_else(|| format!("Byse: Keine file_code-Antwort (Payload: {})", &raw[..raw.len().min(400)]));
    Err(if err_msg.contains("lehnte Datei ab") {
        AppError::FileRejected(err_msg)
    } else {
        AppError::HosterError("Byse".into(), err_msg)
    })
}

async fn get_upload_server(c: &Client, key: &str) -> AppResult<String> {
    let url = format!("{API_BASE}/upload/server?key={}", urlencoding::encode(key));
    let resp = c.get(&url).header("Accept", "application/json").send().await?;
    let status = resp.status();
    let text = resp.text().await.unwrap_or_default();
    if !status.is_success() {
        return Err(AppError::HosterError("Byse".into(),
            format!("/upload/server HTTP {}: {}", status, &text[..text.len().min(200)])));
    }
    let v: serde_json::Value = serde_json::from_str(&text).map_err(|_|
        AppError::BadResponse(format!("Byse /upload/server kein JSON: {}", &text[..text.len().min(200)])))?;
    // Common shapes: { result: "https://..." } or { upload_url: "..." }
    for k in ["result", "upload_url", "url", "server"] {
        if let Some(s) = v.get(k).and_then(|x| x.as_str()) {
            if s.starts_with("http") { return Ok(s.to_string()); }
        }
    }
    Err(AppError::BadResponse("Byse: Kein Upload-Server erhalten".into()))
}

fn append_query(url: &str, key: &str, val: &str) -> String {
    if url.contains('?') {
        format!("{url}&{key}={}", urlencoding::encode(val))
    } else {
        format!("{url}?{key}={}", urlencoding::encode(val))
    }
}

fn is_ok_ish(s: &str) -> bool {
    let l = s.to_lowercase();
    matches!(l.as_str(), "ok" | "success" | "done")
}

// --- File-list polling ---

#[derive(Debug, Default, Clone)]
struct ByseFile {
    file_code: String,
    name: String,
}

async fn fetch_file_list(c: &Client, key: &str) -> AppResult<Vec<ByseFile>> {
    let url = format!("{API_BASE}/api/file/list?key={}&per_page=100&sort=date&order=desc",
        urlencoding::encode(key));
    let resp = c.get(&url)
        .header("Accept", "application/json")
        .timeout(Duration::from_secs(30))
        .send()
        .await?;
    if !resp.status().is_success() { return Ok(vec![]); }
    let text = resp.text().await.unwrap_or_default();
    let v: serde_json::Value = match serde_json::from_str(&text) {
        Ok(v) => v,
        Err(_) => return Ok(vec![]),
    };
    let mut list = Vec::new();
    let arr = v.get("files").and_then(|x| x.as_array()).cloned()
        .or_else(|| v.pointer("/result/files").and_then(|x| x.as_array()).cloned())
        .or_else(|| v.get("result").and_then(|x| x.as_array()).cloned())
        .unwrap_or_default();
    for f in arr {
        let file_code = f.get("file_code").and_then(|x| x.as_str())
            .or_else(|| f.get("filecode").and_then(|x| x.as_str()))
            .unwrap_or("").to_string();
        if file_code.is_empty() { continue; }
        let name = f.get("title").and_then(|x| x.as_str())
            .or_else(|| f.get("name").and_then(|x| x.as_str()))
            .or_else(|| f.get("file_name").and_then(|x| x.as_str()))
            .unwrap_or("").to_string();
        list.push(ByseFile { file_code, name });
    }
    Ok(list)
}

fn normalize_title(s: &str) -> String {
    let mut out = String::with_capacity(s.len());
    for c in s.chars() {
        if c.is_ascii_alphanumeric() { out.push(c.to_ascii_lowercase()); }
    }
    // Strip trailing extension, e.g. ".mkv"
    if let Some(idx) = out.rfind(|_| false) { let _ = idx; }
    out
}

async fn poll_for_upload(
    c: &Client,
    key: &str,
    file_name: &str,
    baseline: &std::collections::HashSet<String>,
    ctx: &UploadCtx,
) -> Option<String> {
    let expected = {
        // strip file extension before normalizing
        let stripped = std::path::Path::new(file_name)
            .file_stem()
            .and_then(|s| s.to_str())
            .unwrap_or(file_name);
        normalize_title(stripped)
    };
    for _ in 0..15 {
        if ctx.is_aborted() { return None; }
        if let Ok(list) = fetch_file_list(c, key).await {
            let new_files: Vec<_> = list.into_iter()
                .filter(|f| !baseline.contains(&f.file_code))
                .collect();
            if let Some(exact) = new_files.iter()
                .find(|f| normalize_title(&f.name) == expected) {
                return Some(exact.file_code.clone());
            }
            if new_files.len() == 1 {
                return Some(new_files[0].file_code.clone());
            }
        }
        tokio::time::sleep(Duration::from_secs(2)).await;
    }
    None
}

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),
            }
        }
    })
}

// --- Response shape ---

#[derive(Deserialize, Default)]
struct ByseResp {
    #[allow(dead_code)]
    msg: Option<String>,
    #[allow(dead_code)]
    status: Option<u32>,
    files: Option<Vec<ByseFileEntry>>,
}

#[derive(Deserialize, Default)]
struct ByseFileEntry {
    filecode: Option<String>,
    #[serde(rename = "file_code")]
    file_code: Option<String>,
    #[allow(dead_code)]
    filename: Option<String>,
    status: Option<String>,
}