// SPDX-License-Identifier: LGPL-2.1-only
// Copyright (C) 2026 Liberux Labs, S. L. <info@liberux.net>

//! A print dialog with a preview of the pages, and the system's printers through CUPS. The app renders the
//! document to PDF itself: the dialog asks it for a preview whenever the layout changes, and says where to
//! print and how once the user accepts.
//!
//! ```rust,no_run
//! # use ltk::{ ChannelSender, Element };
//! # use ltk::print::{ Destination, PrintDialog, PrintDialogMsg, PrintEvent };
//! # #[ derive( Clone ) ] enum Msg { Print( PrintDialogMsg ) }
//! # struct App { print: Option<PrintDialog<Msg>>, sender: ChannelSender<Msg> }
//! # impl App {
//! fn open( &mut self )
//! {
//!     self.print = Some( PrintDialog::new( &self.sender, Msg::Print, "Report" ).preview( true ) );
//! }
//!
//! fn update( &mut self, msg: Msg )
//! {
//!     let Msg::Print( msg ) = msg;
//!     let Some( dialog ) = &mut self.print else { return };
//!     match dialog.update( msg )
//!     {
//!         Some( PrintEvent::Preview( options ) ) => { /* render, then send PrintDialogMsg::previewed( .. ) */ }
//!         Some( PrintEvent::Print( job ) )       => { self.print = None; /* render job.options, then ltk::print::send or save */ }
//!         Some( PrintEvent::Cancelled )          => self.print = None,
//!         None                                   => {}
//!     }
//! }
//! # fn view( &self ) -> Element<Msg> { self.print.as_ref().unwrap().view() }
//! # }
//! ```

mod options;
mod view;
pub mod gtk;
#[ cfg( all( feature = "wayland", target_os = "linux" ) ) ]
mod portal;
#[ cfg( all( unix, not( target_os = "android" ), not( target_arch = "wasm32" ) ) ) ]
mod cups;
#[ cfg( not( all( unix, not( target_os = "android" ), not( target_arch = "wasm32" ) ) ) ) ]
#[ path = "none.rs" ]
mod cups;

pub use options::{ format_pages, parse_pages, Margins, Orientation, Paper, PrintOptions, Sides, PAPERS };

/// CUPS's calls themselves, for a program without ltk's loop; each blocks.
pub mod blocking
{
	pub use super::cups::{ cancel, jobs, print, printers, set_default };
}

use std::sync::Arc;

use crate::app::ChannelSender;
use crate::types::WidgetId;
use crate::wallpaper::ImageData;
use crate::widget::Element;

/// The field with the pages to print.
pub const PAGES: WidgetId = WidgetId( "ltk.print.pages" );
/// How wide, in pixels, the pages of a preview are best rendered.
pub const PREVIEW_WIDTH: u32 = 480;

#[ derive( Clone, Copy, Debug, PartialEq, Eq ) ]
pub enum PrinterState
{
	Idle,
	Printing,
	Stopped,
	Unknown,
}

#[ derive( Clone, Debug, PartialEq ) ]
pub struct Printer
{
	/// The queue's name, which CUPS knows it by.
	pub name:        String,
	pub instance:    Option<String>,
	/// What to call it: its description, or else its name.
	pub description: String,
	pub location:    String,
	pub model:       String,
	pub state:       PrinterState,
	/// IPP's `printer-state-reasons`, empty when there are none.
	pub reasons:     String,
	pub accepting:   bool,
	pub default:     bool,
}

#[ derive( Clone, Copy, Debug, PartialEq, Eq ) ]
pub enum JobState
{
	Pending,
	Held,
	Printing,
	Stopped,
	Cancelled,
	Aborted,
	Completed,
}

impl JobState
{
	pub( crate ) fn from_ipp( state: i32 ) -> Self
	{
		match state
		{
			3 => JobState::Pending,
			4 => JobState::Held,
			5 => JobState::Printing,
			6 => JobState::Stopped,
			7 => JobState::Cancelled,
			8 => JobState::Aborted,
			_ => JobState::Completed,
		}
	}
}

#[ derive( Clone, Debug, PartialEq ) ]
pub struct Job
{
	pub id:      i32,
	pub printer: String,
	pub title:   String,
	pub state:   JobState,
	pub size_kb: u32,
	/// Seconds since the epoch.
	pub created: i64,
}

/// What the print portal's dialog chose, which it prints with.
#[ derive( Clone, Debug, PartialEq, Eq ) ]
pub struct PortalToken( pub( crate ) u32 );

#[ derive( Clone, Debug, PartialEq ) ]
pub enum Destination
{
	Printer( Printer ),
	Pdf,
	/// The desktop prints for an app in a sandbox, where the user chose in its own dialog.
	Portal( PortalToken ),
}

/// What to print, where and how, once the user accepted.
#[ derive( Clone, Debug, PartialEq ) ]
pub struct PrintJob
{
	pub destination: Destination,
	pub options:     PrintOptions,
	pub title:       String,
}

#[ derive( Clone, Debug ) ]
pub struct PreviewPage
{
	/// In the document, from 0.
	pub index: usize,
	pub image: ImageData,
}

/// The pages chosen, rendered with the options the dialog asked for.
#[ derive( Clone, Debug ) ]
pub struct Preview
{
	/// The pages of the whole document.
	pub total: usize,
	pub pages: Vec<PreviewPage>,
}

/// What the app has to do for the dialog.
#[ derive( Clone, Debug, PartialEq ) ]
pub enum PrintEvent
{
	/// Render a preview with these options and answer with [`PrintDialogMsg::previewed`].
	Preview( PrintOptions ),
	Print( PrintJob ),
	Cancelled,
}

/// A setting whose choices the dialog shows under it.
#[ derive( Clone, Copy, Debug, PartialEq, Eq ) ]
pub enum Section
{
	Destination,
	Paper,
	Orientation,
	Margins,
	Sides,
}

#[ derive( Clone, Debug ) ]
pub enum PrintDialogMsg
{
	Start,
	Printers( Result<Vec<Printer>, String> ),
	/// The portal's dialog closed: the options and token, `None` when cancelled.
	Prepared( Result<Option<( PrintOptions, u32 )>, String> ),
	Previewed( Result<Preview, String> ),
	Toggle( Section ),
	/// A printer by its place in the list, or `None` for a PDF.
	Destination( Option<usize> ),
	Copies( i32 ),
	AllPages,
	SomePages,
	Pages( String ),
	Paper( usize ),
	Orientation( Orientation ),
	Margins( Margins ),
	Scale( i32 ),
	Color,
	Sides( Sides ),
	Backgrounds,
	Page( i32 ),
	Print,
	Cancel,
}

impl PrintDialogMsg
{
	/// The app's answer to [`PrintEvent::Preview`].
	pub fn previewed( result: Result<Preview, String> ) -> Self
	{
		PrintDialogMsg::Previewed( result )
	}
}

const SCALE_STEP: i32 = 10;

pub struct PrintDialog<Msg>
{
	pub( crate ) title:        String,
	pub( crate ) printers:     Vec<Printer>,
	pub( crate ) listing:      bool,
	pub( crate ) list_error:   Option<String>,
	/// A printer of `printers`, or `None` for a PDF.
	pub( crate ) destination:  Option<usize>,
	pub( crate ) wanted:       Option<String>,
	pub( crate ) prefer_pdf:   bool,
	pub( crate ) options:      PrintOptions,
	pub( crate ) some_pages:   bool,
	pub( crate ) pages_text:   String,
	pub( crate ) pages_bad:    bool,
	pub( crate ) open:         Option<Section>,
	pub( crate ) previews:     bool,
	pub( crate ) preview:      Option<Preview>,
	/// The preview's images as shown, in grey when printing without colour.
	pub( crate ) images:       Vec<ImageData>,
	pub( crate ) preview_error: Option<String>,
	/// The options a preview is being rendered with.
	pub( crate ) rendering:    Option<PrintOptions>,
	pub( crate ) shown:        usize,
	pub( crate ) compact:      bool,
	/// The portal shows the dialog instead.
	pub( crate ) portal:       bool,
	focus:                     Option<WidgetId>,
	sender:                    ChannelSender<Msg>,
	pub( crate ) wrap:         Arc<dyn Fn( PrintDialogMsg ) -> Msg + Send + Sync>,
}

impl<Msg: Clone + Send + 'static> PrintDialog<Msg>
{
	/// A dialog for printing the document called `title`. `wrap` makes the app's message of the dialog's own.
	pub fn new( sender: &ChannelSender<Msg>, wrap: impl Fn( PrintDialogMsg ) -> Msg + Send + Sync + 'static, title: impl Into<String> ) -> Self
	{
		let wrap: Arc<dyn Fn( PrintDialogMsg ) -> Msg + Send + Sync> = Arc::new( wrap );
		let _ = sender.send( wrap( PrintDialogMsg::Start ) );
		let portal = sandboxed();
		if !portal
		{
			let reply = Arc::clone( &wrap );
			list_printers( sender, move |result| reply( PrintDialogMsg::Printers( result ) ) );
		}
		Self
		{
			title:         title.into(),
			printers:      Vec::new(),
			listing:       !portal,
			list_error:    None,
			destination:   None,
			wanted:        None,
			prefer_pdf:    false,
			options:       PrintOptions::default(),
			some_pages:    false,
			pages_text:    String::new(),
			pages_bad:     false,
			open:          None,
			previews:      false,
			preview:       None,
			images:        Vec::new(),
			preview_error: None,
			rendering:     None,
			shown:         0,
			compact:       false,
			portal,
			focus:         None,
			sender:        sender.clone(),
			wrap,
		}
	}

	/// Ask the app for a preview of the pages, which it renders on [`PrintEvent::Preview`].
	pub fn preview( mut self, on: bool ) -> Self
	{
		self.previews = on;
		self
	}

	/// Start with these options, as the app kept them from a [`PrintJob`].
	pub fn options( mut self, options: PrintOptions ) -> Self
	{
		self.some_pages = !options.pages.is_empty();
		self.pages_text = format_pages( &options.pages );
		self.options    = options;
		self
	}

	/// Choose this printer, by its queue's name, rather than the default one once the printers are known.
	pub fn printer( mut self, name: impl Into<String> ) -> Self
	{
		self.wanted = Some( name.into() );
		self
	}

	/// Start with saving to PDF chosen, even when there are printers.
	pub fn save_as_pdf( mut self ) -> Self
	{
		self.prefer_pdf = true;
		self
	}

	/// Laid out for a narrow screen, on the whole of it.
	pub fn compact( mut self, on: bool ) -> Self
	{
		self.compact = on;
		self
	}

	/// The field to focus, once after it changed; an app hands it on from [`crate::App::take_focus_request`].
	pub fn take_focus_request( &mut self ) -> Option<WidgetId>
	{
		self.focus.take()
	}

	/// Nothing while the portal shows its own dialog.
	pub fn view( &self ) -> Element<Msg>
	{
		if self.portal { return crate::spacer().into(); }
		view::view( self )
	}

	/// Take one of the dialog's messages; `Some` when the app has something to do.
	pub fn update( &mut self, msg: PrintDialogMsg ) -> Option<PrintEvent>
	{
		match msg
		{
			PrintDialogMsg::Start if self.portal =>
			{
				let ( title, options, wrap ) = ( self.title.clone(), self.options.clone(), Arc::clone( &self.wrap ) );
				run( &self.sender, move || prepare( &title, &options ), move |result| wrap( PrintDialogMsg::Prepared( result ) ) );
			}
			PrintDialogMsg::Start => return self.request_preview(),
			PrintDialogMsg::Printers( result ) => self.listed( result ),
			PrintDialogMsg::Prepared( result ) => match result
			{
				Ok( Some( ( options, token ) ) ) =>
				{
					return Some( PrintEvent::Print( PrintJob { destination: Destination::Portal( PortalToken( token ) ), options, title: self.title.clone() } ) );
				}
				Ok( None ) => return Some( PrintEvent::Cancelled ),
				Err( error ) =>
				{
					self.portal     = false;
					self.list_error = Some( error );
					return self.request_preview();
				}
			},
			PrintDialogMsg::Previewed( result ) => return self.previewed( result ),
			PrintDialogMsg::Toggle( section ) => self.open = if self.open == Some( section ) { None } else { Some( section ) },
			PrintDialogMsg::Destination( index ) =>
			{
				self.destination = index.filter( |i| *i < self.printers.len() );
				self.open        = None;
			}
			PrintDialogMsg::Copies( delta ) =>
			{
				self.options.copies = ( self.options.copies as i64 + delta as i64 ).clamp( 1, PrintOptions::MAX_COPIES as i64 ) as u32;
			}
			PrintDialogMsg::AllPages =>
			{
				self.some_pages = false;
				self.pages_bad  = false;
				return self.set_pages( Vec::new() );
			}
			PrintDialogMsg::SomePages =>
			{
				self.some_pages = true;
				self.focus      = Some( PAGES );
				if let Some( pages ) = parse_pages( &self.pages_text ) { return self.set_pages( pages ); }
			}
			PrintDialogMsg::Pages( text ) =>
			{
				self.pages_text = text;
				match parse_pages( &self.pages_text )
				{
					Some( pages ) =>
					{
						self.pages_bad = false;
						return self.set_pages( pages );
					}
					None => self.pages_bad = !self.pages_text.trim().is_empty(),
				}
			}
			PrintDialogMsg::Paper( index ) =>
			{
				self.open = None;
				if let Some( paper ) = PAPERS.get( index ) { return self.change( |o| o.paper = *paper ); }
			}
			PrintDialogMsg::Orientation( orientation ) =>
			{
				self.open = None;
				return self.change( |o| o.orientation = orientation );
			}
			PrintDialogMsg::Margins( margins ) =>
			{
				self.open = None;
				return self.change( |o| o.margins = margins );
			}
			PrintDialogMsg::Scale( steps ) =>
			{
				let percent = ( self.options.scale * 100.0 ).round() as i32 + steps * SCALE_STEP;
				let scale   = ( percent as f32 / 100.0 ).clamp( PrintOptions::MIN_SCALE, PrintOptions::MAX_SCALE );
				return self.change( |o| o.scale = scale );
			}
			PrintDialogMsg::Color =>
			{
				self.options.color = !self.options.color;
				self.refresh_images();
			}
			PrintDialogMsg::Sides( sides ) =>
			{
				self.open          = None;
				self.options.sides = sides;
			}
			PrintDialogMsg::Backgrounds => return self.change( |o| o.backgrounds = !o.backgrounds ),
			PrintDialogMsg::Page( delta ) =>
			{
				let last   = self.images.len().saturating_sub( 1 ) as i64;
				self.shown = ( self.shown as i64 + delta as i64 ).clamp( 0, last ) as usize;
			}
			PrintDialogMsg::Print => return self.job().map( PrintEvent::Print ),
			PrintDialogMsg::Cancel => return Some( PrintEvent::Cancelled ),
		}
		None
	}

	/// Where it prints to now.
	pub fn destination( &self ) -> Destination
	{
		match self.destination.and_then( |i| self.printers.get( i ) )
		{
			Some( printer ) => Destination::Printer( printer.clone() ),
			None            => Destination::Pdf,
		}
	}

	pub( crate ) fn msg( &self, msg: PrintDialogMsg ) -> Msg
	{
		( self.wrap )( msg )
	}

	pub( crate ) fn can_print( &self ) -> bool
	{
		!( self.some_pages && ( self.pages_bad || parse_pages( &self.pages_text ).is_none() ) )
	}

	fn job( &self ) -> Option<PrintJob>
	{
		if !self.can_print() { return None; }
		let mut options = self.options.clone();
		if !self.some_pages { options.pages.clear(); }
		Some( PrintJob { destination: self.destination(), options, title: self.title.clone() } )
	}

	fn listed( &mut self, result: Result<Vec<Printer>, String> )
	{
		self.listing = false;
		match result
		{
			Ok( printers ) =>
			{
				let wanted = self.wanted.as_deref();
				self.destination = if self.prefer_pdf
				{
					None
				} else {
					printers.iter().position( |p| Some( p.name.as_str() ) == wanted )
						.or_else( || printers.iter().position( |p| p.default ) )
						.or( ( !printers.is_empty() ).then_some( 0 ) )
				};
				self.printers = printers;
			}
			Err( error ) => self.list_error = Some( error ),
		}
	}

	fn set_pages( &mut self, pages: Vec<( u32, u32 )> ) -> Option<PrintEvent>
	{
		self.change( |o| o.pages = pages )
	}

	fn change( &mut self, apply: impl FnOnce( &mut PrintOptions ) ) -> Option<PrintEvent>
	{
		let before = self.options.clone();
		apply( &mut self.options );
		if before.same_layout( &self.options ) { return None; }
		self.request_preview()
	}

	fn request_preview( &mut self ) -> Option<PrintEvent>
	{
		if !self.previews || self.rendering.is_some() { return None; }
		self.rendering = Some( self.options.clone() );
		Some( PrintEvent::Preview( self.options.clone() ) )
	}

	fn previewed( &mut self, result: Result<Preview, String> ) -> Option<PrintEvent>
	{
		let rendered = self.rendering.take();
		match result
		{
			Ok( preview ) =>
			{
				self.preview_error = None;
				self.shown         = self.shown.min( preview.pages.len().saturating_sub( 1 ) );
				self.preview       = Some( preview );
				self.refresh_images();
			}
			Err( error ) => self.preview_error = Some( error ),
		}
		match rendered
		{
			Some( rendered ) if !rendered.same_layout( &self.options ) => self.request_preview(),
			_ => None,
		}
	}

	fn refresh_images( &mut self )
	{
		let color = self.options.color;
		self.images = self.preview.iter()
			.flat_map( |preview| preview.pages.iter() )
			.map( |page| if color { page.image.clone() } else { grey( &page.image ) } )
			.collect();
	}
}

fn grey( ( rgba, width, height ): &ImageData ) -> ImageData
{
	let mut out = rgba.as_ref().clone();
	for px in out.chunks_exact_mut( 4 )
	{
		let y = ( 0.299 * px[ 0 ] as f32 + 0.587 * px[ 1 ] as f32 + 0.114 * px[ 2 ] as f32 ).round() as u8;
		px[ 0 ] = y;
		px[ 1 ] = y;
		px[ 2 ] = y;
	}
	( Arc::new( out ), *width, *height )
}

fn run<M: Send + 'static, T: Send + 'static>( sender: &ChannelSender<M>, work: impl FnOnce() -> T + Send + 'static, done: impl FnOnce( T ) -> M + Send + 'static )
{
	let sender = sender.clone();
	#[ cfg( target_arch = "wasm32" ) ]
	let _ = sender.send( done( work() ) );
	#[ cfg( not( target_arch = "wasm32" ) ) ]
	std::thread::spawn( move || { let _ = sender.send( done( work() ) ); } );
}

/// The system's printers, the default first; empty without CUPS's server, an error without CUPS.
pub fn list_printers<M: Send + 'static>( sender: &ChannelSender<M>, done: impl FnOnce( Result<Vec<Printer>, String> ) -> M + Send + 'static )
{
	run( sender, cups::printers, done );
}

/// Print `pdf` at `destination` with `options`; done once the printer's queue, or the desktop, took it.
pub fn send<M: Send + 'static>( destination: &Destination, title: &str, options: &PrintOptions, pdf: Vec<u8>, sender: &ChannelSender<M>, done: impl FnOnce( Result<(), String> ) -> M + Send + 'static )
{
	let ( destination, title, options ) = ( destination.clone(), title.to_string(), options.clone() );
	run( sender, move || match destination
	{
		Destination::Printer( printer ) => cups::print( &printer, &title, &options, &pdf ).map( |_| () ),
		Destination::Portal( token )    => portal_print( token.0, &title, &pdf ),
		Destination::Pdf                => Err( rust_i18n::t!( "print.failed" ).to_string() ),
	}, done );
}

#[ cfg( all( feature = "wayland", target_os = "linux" ) ) ]
use portal::{ prepare, print as portal_print, sandboxed };

#[ cfg( not( all( feature = "wayland", target_os = "linux" ) ) ) ]
fn sandboxed() -> bool
{
	false
}

#[ cfg( not( all( feature = "wayland", target_os = "linux" ) ) ) ]
fn prepare( _title: &str, _options: &PrintOptions ) -> Result<Option<( PrintOptions, u32 )>, String>
{
	Err( rust_i18n::t!( "print.no_cups" ).to_string() )
}

#[ cfg( not( all( feature = "wayland", target_os = "linux" ) ) ) ]
fn portal_print( _token: u32, _title: &str, _pdf: &[ u8 ] ) -> Result<(), String>
{
	Err( rust_i18n::t!( "print.no_cups" ).to_string() )
}

/// The user's jobs not yet finished, on every printer or on one of them.
pub fn jobs<M: Send + 'static>( printer: Option<String>, sender: &ChannelSender<M>, done: impl FnOnce( Result<Vec<Job>, String> ) -> M + Send + 'static )
{
	run( sender, move || cups::jobs( printer.as_deref() ), done );
}

pub fn cancel_job<M: Send + 'static>( printer: &str, job: i32, sender: &ChannelSender<M>, done: impl FnOnce( Result<(), String> ) -> M + Send + 'static )
{
	let printer = printer.to_string();
	run( sender, move || cups::cancel( &printer, job ), done );
}

/// Make `printer` the user's default.
pub fn set_default<M: Send + 'static>( printer: &Printer, sender: &ChannelSender<M>, done: impl FnOnce( Result<(), String> ) -> M + Send + 'static )
{
	let ( name, instance ) = ( printer.name.clone(), printer.instance.clone() );
	run( sender, move || cups::set_default( &name, instance.as_deref() ), done );
}