use axum::{
    extract::{DefaultBodyLimit, Multipart, Path as AxumPath, State},
    http::StatusCode,
    response::IntoResponse,
    routing::{get, post},
    Json, Router,
};
use serde::{Deserialize, Serialize};
use std::{
    collections::HashMap,
    path::{Path, PathBuf},
    process::Command,
    sync::{
        atomic::{AtomicU64, Ordering},
        Arc, Mutex,
    },
};
use tempfile::{NamedTempFile, TempPath};
use tokio::fs;
use tower_http::cors::CorsLayer;
use tracing::info;

async fn get_version() -> impl IntoResponse {
    Json(serde_json::json!({
        "version": "1.0.6",
        "timestamp": chrono::Utc::now().timestamp()
    }))
}

// ─────────────────────────────── Модели ───────────────────────────────

#[derive(Deserialize, Clone, Debug)]
struct PrintSettings {
    filename: String,
    pages: String,
    copies: u32,
    #[serde(rename = "colorMode")]
    color_mode: String,
    format: String,
    #[serde(default)]
    sides: Option<String>,
    #[serde(default)]
    dpi: Option<String>,
}

#[derive(Clone, Debug, Serialize, PartialEq)]
#[serde(rename_all = "snake_case")]
enum FileStatus {
    Queued,
    Printing,
    Sent,
    AwaitingClearOutput,
    AwaitingFlip,
    AwaitingPickup,
    Done,
    Error,
    Cancelled,
}

#[derive(Clone, Debug, Serialize, PartialEq)]
#[serde(rename_all = "snake_case")]
enum JobPhase {
    WaitingStart,
    Printing,
    AwaitingClearOutput,
    AwaitingFlip,
    AwaitingPickup,
    Finished,
    Cancelled,
}

#[derive(Clone, Debug, Serialize)]
struct JobFileView {
    name: String,
    status: FileStatus,
    #[serde(skip_serializing_if = "Option::is_none")]
    error: Option<String>,
    #[serde(default)]
    remove_top_sheet: bool,
}

#[derive(Clone, Debug, Serialize)]
struct JobView {
    job_id: String,
    phase: JobPhase,
    files: Vec<JobFileView>,
}

struct JobFile {
    name: String,
    path: TempPath,
    settings: Option<PrintSettings>,
    status: FileStatus,
    error: Option<String>,
}

struct Job {
    id: String,
    files: Vec<JobFile>,
    current: Option<usize>,
    phase: JobPhase,
    cups_id: Option<String>,
    /// true если только что завершился ПЕРВЫЙ проход дуплекса
    duplex_first_pass_done: bool,
}

impl Job {
    fn view(&self) -> JobView {
        JobView {
            job_id: self.id.clone(),
            phase: self.phase.clone(),
            files: self.files.iter().map(|f| {
                JobFileView {
                    name: f.name.clone(),
                    status: f.status.clone(),
                    error: f.error.clone(),
                    remove_top_sheet: Self::should_remove_top_sheet(&f.settings),
                }
            }).collect(),
        }
    }

    fn is_current_duplex(&self) -> bool {
        self.current
            .and_then(|i| self.files.get(i))
            .and_then(|f| f.settings.as_ref())
            .map(|s| s.sides.as_deref() == Some("Двусторонняя"))
            .unwrap_or(false)
    }

    fn should_remove_top_sheet(settings: &Option<PrintSettings>) -> bool {
        let Some(s) = settings else { return false };
        if s.sides.as_deref() != Some("Двусторонняя") { return false; }
        if s.pages == "all" { return false; }
        let nums: Vec<u32> = s.pages.split(',')
            .filter_map(|p| p.trim().parse().ok())
            .collect();
        let odd  = nums.iter().filter(|n| *n % 2 == 1).count();
        let even = nums.iter().filter(|n| *n % 2 == 0).count();
        odd > even
    }
}

#[derive(Clone)]
struct SpawnInfo {
    job_id: String,
    idx: usize,
    path: PathBuf,
    settings: Option<PrintSettings>,
    is_second_pass: bool,
}

type JobStore = Arc<Mutex<HashMap<String, Job>>>;
static JOB_COUNTER: AtomicU64 = AtomicU64::new(1);

// ─────────────────────────────── main ───────────────────────────────

#[tokio::main]
async fn main() {
    tracing_subscriber::fmt()
        .with_target(true)
        .with_thread_ids(true)
        .with_file(true)
        .with_line_number(true)
        .init();

    let store: JobStore = Arc::new(Mutex::new(HashMap::new()));
    let cors = CorsLayer::permissive();

    let app = Router::new()
        .route("/version", get(get_version))
        .route("/print", post(create_print))
        .route("/print/{job_id}", get(job_status))
        .route("/print/{job_id}/advance", post(job_advance))
        .route("/print/{job_id}/cancel", post(job_cancel))
        .layer(DefaultBodyLimit::max(50 * 1024 * 1024))
        .layer(cors)
        .with_state(store);

    info!("🖨️  Print API запущен на http://0.0.0.0:3000");
    let listener = tokio::net::TcpListener::bind("0.0.0.0:3000")
        .await
        .expect("Не удалось забиндить порт 3000");
    axum::serve(listener, app).await.expect("Ошибка сервера");
}

// ─────────────────────────── Обработчики ───────────────────────────

async fn create_print(
    State(store): State<JobStore>,
    mut multipart: Multipart,
) -> Result<Json<JobView>, (StatusCode, String)> {
    info!("📥 Получен запрос на печать");

    let mut settings_map: HashMap<String, PrintSettings> = HashMap::new();
    let mut files_data: Vec<(String, bytes::Bytes)> = Vec::new();

    while let Some(field) = multipart.next_field().await.unwrap_or(None) {
        let field_name = field.name().unwrap_or("").to_string();
        if field_name == "settings" {
            if let Ok(text) = field.text().await {
                if let Ok(s) = serde_json::from_str::<PrintSettings>(&text) {
                    settings_map.insert(s.filename.clone(), s);
                }
            }
        } else if field_name == "files" {
            let file_name = field.file_name().unwrap_or("unknown").to_string();
            if let Ok(data) = field.bytes().await {
                files_data.push((file_name, data));
            }
        }
    }

    if files_data.is_empty() {
        return Err((StatusCode::BAD_REQUEST, "Нет файлов".into()));
    }

    let mut job_files: Vec<JobFile> = Vec::new();
    for (file_name, data) in files_data {
        let ext = Path::new(&file_name)
            .extension()
            .and_then(|e| e.to_str())
            .unwrap_or("")
            .to_lowercase();
        let temp = if ext.is_empty() {
            NamedTempFile::new()
        } else {
            NamedTempFile::with_suffix(&format!(".{}", ext))
        };
        if let Ok(temp) = temp {
            let path = temp.into_temp_path();
            if fs::write(&*path, &data).await.is_ok() {
                let settings = settings_map.get(&file_name).cloned();
                job_files.push(JobFile {
                    name: file_name,
                    path,
                    settings,
                    status: FileStatus::Queued,
                    error: None,
                });
            }
        }
    }

    if job_files.is_empty() {
        return Err((StatusCode::BAD_REQUEST, "Не удалось сохранить файлы".into()));
    }

    let job_id = format!("job-{}", JOB_COUNTER.fetch_add(1, Ordering::SeqCst));
    let job = Job {
        id: job_id.clone(),
        files: job_files,
        current: None,
        phase: JobPhase::WaitingStart,
        cups_id: None,
        duplex_first_pass_done: false,
    };

    let view = job.view();
    store.lock().unwrap().insert(job_id.clone(), job);
    Ok(Json(view))
}

async fn job_status(
    State(store): State<JobStore>,
    AxumPath(job_id): AxumPath<String>,
) -> Result<Json<JobView>, (StatusCode, String)> {
    let m = store.lock().unwrap();
    m.get(&job_id)
        .map(|j| Json(j.view()))
        .ok_or_else(|| (StatusCode::NOT_FOUND, "Задание не найдено".into()))
}

async fn job_advance(
    State(store): State<JobStore>,
    AxumPath(job_id): AxumPath<String>,
) -> Result<Json<JobView>, (StatusCode, String)> {
    let (view, spawn_info) = {
        let mut m = store.lock().unwrap();
        let job = m.get_mut(&job_id)
            .ok_or_else(|| (StatusCode::NOT_FOUND, "Задание не найдено".into()))?;

        let si = match job.phase {
            // ── Старт: первый файл ──
            JobPhase::WaitingStart => {
                let next_idx = 0;
                job.current = Some(next_idx);
                Some(start_printing_locked(job, next_idx))
            }

            // ── Пользователь подтвердил «забрал / печать закончена» ──
            JobPhase::AwaitingPickup => {
                let c = job.current.unwrap_or(0);

                if job.duplex_first_pass_done {
                    // Первый проход дуплекса завершён → просим убрать листы
                    job.duplex_first_pass_done = false;
                    job.files[c].status = FileStatus::AwaitingClearOutput;
                    job.phase = JobPhase::AwaitingClearOutput;
                    None
                } else {
                    // Обычная печать или второй проход дуплекса → файл готов
                    job.files[c].status = FileStatus::Done;
                    begin_next_locked(job, c)
                }
            }

            // ── Пользователь убрал листы из выходного лотка ──
            JobPhase::AwaitingClearOutput => {
                let c = job.current.unwrap_or(0);
                job.files[c].status = FileStatus::AwaitingFlip;
                job.phase = JobPhase::AwaitingFlip;
                None
            }

            // ── Пользователь переложил бумагу → запускаем второй проход ──
            JobPhase::AwaitingFlip => {
                let c = job.current.unwrap();
                job.files[c].status = FileStatus::Printing;
                job.phase = JobPhase::Printing;
                Some(SpawnInfo {
                    job_id: job.id.clone(),
                    idx: c,
                    path: job.files[c].path.to_path_buf(),
                    settings: job.files[c].settings.clone(),
                    is_second_pass: true,
                })
            }

            _ => None,
        };

        (job.view(), si)
    };

    if let Some(si) = spawn_info {
        spawn_print_task(store.clone(), si);
    }
    Ok(Json(view))
}

async fn job_cancel(
    State(store): State<JobStore>,
    AxumPath(job_id): AxumPath<String>,
) -> Result<Json<JobView>, (StatusCode, String)> {
    let cups_ids: Vec<String> = {
        let mut m = store.lock().unwrap();
        let job = m.get_mut(&job_id)
            .ok_or_else(|| (StatusCode::NOT_FOUND, "Задание не найдено".into()))?;

        if job.phase == JobPhase::Finished || job.phase == JobPhase::Cancelled {
            return Ok(Json(job.view()));
        }

        let ids = job.cups_id.take().into_iter().collect::<Vec<_>>();
        for f in job.files.iter_mut() {
            if matches!(f.status, FileStatus::Queued | FileStatus::Printing) {
                f.status = FileStatus::Cancelled;
            }
        }
        job.phase = JobPhase::Cancelled;
        job.current = None;
        ids
    };

    for id in cups_ids {
        let cancel_bin = cups_bin("cancel");
        let _ = tokio::task::spawn_blocking(move || {
            Command::new(cancel_bin).arg(id).env("LC_ALL", "C").output()
        }).await;
    }

    let m = store.lock().unwrap();
    Ok(Json(m.get(&job_id).unwrap().view()))
}

// ─────────────────────── Печать: state machine ───────────────────────

fn start_printing_locked(job: &mut Job, idx: usize) -> SpawnInfo {
    job.files[idx].status = FileStatus::Printing;
    job.current = Some(idx);
    job.phase = JobPhase::Printing;
    job.cups_id = None;
    job.duplex_first_pass_done = false;
    SpawnInfo {
        job_id: job.id.clone(),
        idx,
        path: job.files[idx].path.to_path_buf(),
        settings: job.files[idx].settings.clone(),
        is_second_pass: false,
    }
}

fn begin_next_locked(job: &mut Job, from: usize) -> Option<SpawnInfo> {
    match (from + 1..job.files.len()).find(|&i| job.files[i].status == FileStatus::Queued) {
        Some(i) => {
            job.current = Some(i);
            Some(start_printing_locked(job, i))
        }
        None => {
            job.phase = JobPhase::Finished;
            job.current = None;
            None
        }
    }
}

fn spawn_print_task(store: JobStore, info: SpawnInfo) {
    tokio::spawn(async move {
        let path     = info.path.clone();
        let settings = info.settings.clone();
        let is_duplex = settings.as_ref()
            .map(|s| s.sides.as_deref() == Some("Двусторонняя"))
            .unwrap_or(false);

        let duplex_pass: Option<&str> = if is_duplex {
            if info.is_second_pass { Some("even") } else { Some("odd") }
        } else {
            None
        };

        let p  = path.clone();
        let s  = settings.clone();
        let dp = duplex_pass.map(|d| d.to_string());

        let spool = tokio::task::spawn_blocking(move || {
            run_lp(&p, s.as_ref(), dp.as_deref())
        }).await;

        let cups_id = match spool {
            Ok(Ok(id)) => id,
            Ok(Err(e)) => return mark_error_and_continue(store, info, e).await,
            Err(e)     => return mark_error_and_continue(store, info, format!("spawn: {}", e)).await,
        };

        let mut m = store.lock().unwrap();
        let job = match m.get_mut(&info.job_id) { Some(j) => j, None => return };
        if job.phase == JobPhase::Cancelled { return; }
        if job.files.get(info.idx).map(|f| f.status.clone()) != Some(FileStatus::Printing) { return; }

        if !cups_id.is_empty() {
            job.cups_id = Some(cups_id);
        }

        if is_duplex && !info.is_second_pass {
            // ── Первый проход дуплекса завершён ──
            // Просим пользователя подтвердить что печать закончена
            job.files[info.idx].status = FileStatus::AwaitingPickup;
            job.phase = JobPhase::AwaitingPickup;
            job.duplex_first_pass_done = true;
        } else {
            // ── Обычная печать или второй проход дуплекса ──
            job.files[info.idx].status = FileStatus::AwaitingPickup;
            job.phase = JobPhase::AwaitingPickup;
            job.duplex_first_pass_done = false;
        }

        job.cups_id = None;
    });
}

async fn mark_error_and_continue(store: JobStore, info: SpawnInfo, msg: String) {
    let next = {
        let mut m = store.lock().unwrap();
        let job = match m.get_mut(&info.job_id) { Some(j) => j, None => return };
        if job.phase == JobPhase::Cancelled { return; }

        if let Some(f) = job.files.get_mut(info.idx) {
            if f.status != FileStatus::Printing { return; }
            f.status = FileStatus::Error;
            f.error = Some(msg);
        }
        begin_next_locked(job, info.idx)
    };

    if let Some(si) = next { spawn_print_task(store, si); }
}

// ─────────────────────────── lp / CUPS ───────────────────────────

fn cups_bin(name: &str) -> std::path::PathBuf {
    let candidates = [
        format!("/pkg/gnu/cups/bin/{}", name),
        format!("/run/current-system/sw/bin/{}", name),
        format!("/usr/bin/{}", name),
        format!("/usr/local/bin/{}", name),
    ];
    for p in &candidates {
        let path = std::path::Path::new(p);
        if path.exists() { return path.to_path_buf(); }
    }
    std::path::PathBuf::from(name)
}

fn normalize_format(format: &str) -> String {
    match format.trim() {
        "" | "Авто" | "auto" => String::new(),
        "10x15" => "10x15cm".to_string(),
        other => other.to_string(),
    }
}

fn run_lp(path: &Path, settings: Option<&PrintSettings>, duplex_pass: Option<&str>) -> Result<String, String> {
    let lp = cups_bin("lp");
    let mut cmd = Command::new(&lp);

    if let Some(s) = settings {
        cmd.arg("-n").arg(s.copies.to_string());
        if s.pages != "all" && !s.pages.is_empty() {
            cmd.arg("-P").arg(&s.pages);
        }
        if s.color_mode == "bw" {
            cmd.arg("-o").arg("ColorModel=Gray");
        }
        let fmt = normalize_format(&s.format);
        if !fmt.is_empty() {
            cmd.arg("-o").arg(format!("PageSize={}", fmt));
        }
        if s.sides.as_deref() == Some("Двусторонняя") && duplex_pass.is_none() {
            cmd.arg("-o").arg("sides=two-sided-long-edge");
        }
        if let Some(d) = s.dpi.as_deref() {
            if !d.is_empty() && d != "Авто" {
                cmd.arg("-o").arg(format!("printer-resolution={}dpi", d));
            }
        }
    }

    // ──────────────────────────────────────────────────────────
    // СЛОТЫ:
    //   • Первый проход дуплекса (odd) → Upper
    //   • Второй проход дуплекса (even) → Lower (ручная подача)
    //   • Обычная печать (не дуплекс)  → Upper
    // ──────────────────────────────────────────────────────────
    match duplex_pass {
        Some("odd") => {
            // ПЕРВЫЙ проход — обычный лоток
            cmd.arg("-o").arg("InputSlot=Upper");
            cmd.arg("-o").arg("page-set=odd");
        }
        Some("even") => {
            // ВТОРОЙ проход — ручная подача
            cmd.arg("-o").arg("InputSlot=Lower");
            cmd.arg("-o").arg("page-set=even");
            cmd.arg("-o").arg("outputorder=reverse");
            cmd.arg("-o").arg("orientation-requested=6");
        }
        _ => {
            // Обычная односторонняя печать
            cmd.arg("-o").arg("InputSlot=Upper");
        }
    }

    cmd.arg(path);

    let out = cmd.env("LC_ALL", "C").output()
        .map_err(|e| format!("lp: {}", e))?;

    if !out.status.success() {
        return Err(String::from_utf8_lossy(&out.stderr).trim().to_string());
    }

    Ok(String::from_utf8_lossy(&out.stdout)
        .split_whitespace()
        .nth(3)
        .unwrap_or("")
        .to_string())
}