/* LICENSE BEGIN
    This file is part of the SixtyFPS Project -- https://sixtyfps.io
    Copyright (c) 2020 Olivier Goffart <olivier.goffart@sixtyfps.io>
    Copyright (c) 2020 Simon Hausmann <simon.hausmann@sixtyfps.io>

    SPDX-License-Identifier: GPL-3.0-only
    This file is also available under commercial licensing terms.
    Please contact info@sixtyfps.io for more information.
LICENSE END */

mod completion;
mod lsp_ext;
mod preview;

use std::collections::HashMap;
use std::path::Path;

use lsp_server::{Connection, Message, Request, RequestId, Response};
use lsp_types::notification::{DidChangeTextDocument, DidOpenTextDocument, Notification};
use lsp_types::request::{CodeActionRequest, ExecuteCommand, GotoDefinition};
use lsp_types::request::{Completion, HoverRequest};
use lsp_types::{
    CodeActionOrCommand, CodeActionProviderCapability, Command, CompletionOptions,
    DidChangeTextDocumentParams, DidOpenTextDocumentParams, ExecuteCommandOptions,
    GotoDefinitionResponse, Hover, HoverProviderCapability, InitializeParams, LocationLink, OneOf,
    Position, PublishDiagnosticsParams, Range, ServerCapabilities, TextDocumentSyncCapability, Url,
    WorkDoneProgressOptions,
};
use sixtyfps_compilerlib::diagnostics::{BuildDiagnostics, Spanned};
use sixtyfps_compilerlib::langtype::Type;
use sixtyfps_compilerlib::parser::{syntax_nodes, SyntaxKind, SyntaxNode, SyntaxToken};
use sixtyfps_compilerlib::typeloader::TypeLoader;
use sixtyfps_compilerlib::typeregister::TypeRegister;
use sixtyfps_compilerlib::{object_tree, CompilerConfiguration};

type Error = Box<dyn std::error::Error>;

const SHOW_PREVIEW_COMMAND: &str = "showPreview";

struct DocumentCache<'a> {
    documents: TypeLoader<'a>,
    newline_offsets: HashMap<Url, Vec<u32>>,
}

impl<'a> DocumentCache<'a> {
    fn new(config: &'a CompilerConfiguration) -> Self {
        let documents =
            TypeLoader::new(TypeRegister::builtin(), config, &mut BuildDiagnostics::default());
        Self { documents, newline_offsets: Default::default() }
    }
}

fn main() {
    std::thread::spawn(|| {
        match run_lsp_server() {
            Ok(_) => {}
            Err(error) => {
                eprintln!("Error running LSP server: {}", error);
            }
        }
        preview::quit_ui_event_loop();
    });

    preview::start_ui_event_loop();
}

fn run_lsp_server() -> Result<(), Error> {
    let (connection, io_threads) = Connection::stdio();
    let capabilities = ServerCapabilities {
        completion_provider: Some(CompletionOptions {
            resolve_provider: Some(true),
            trigger_characters: Some(vec![".".to_owned()]),
            work_done_progress_options: WorkDoneProgressOptions::default(),
        }),
        hover_provider: Some(HoverProviderCapability::Simple(true)),
        document_highlight_provider: Some(OneOf::Left(true)),
        document_symbol_provider: Some(OneOf::Left(true)),
        workspace_symbol_provider: Some(OneOf::Left(true)),
        definition_provider: Some(OneOf::Left(true)),
        text_document_sync: Some(TextDocumentSyncCapability::Kind(
            lsp_types::TextDocumentSyncKind::Full,
        )),
        code_action_provider: Some(CodeActionProviderCapability::Simple(true)),
        execute_command_provider: Some(ExecuteCommandOptions {
            commands: vec![SHOW_PREVIEW_COMMAND.into()],
            ..Default::default()
        }),
        ..ServerCapabilities::default()
    };
    let server_capabilities = serde_json::to_value(&capabilities).unwrap();
    let initialization_params = connection.initialize(server_capabilities)?;
    main_loop(&connection, initialization_params)?;
    io_threads.join()?;
    Ok(())
}

fn main_loop(connection: &Connection, params: serde_json::Value) -> Result<(), Error> {
    let _params: InitializeParams = serde_json::from_value(params).unwrap();
    let mut compiler_config = sixtyfps_compilerlib::CompilerConfiguration::new(
        sixtyfps_compilerlib::generator::OutputFormat::Interpreter,
    );
    compiler_config.style = Some("ugly".into());

    let mut document_cache = DocumentCache::new(&compiler_config);
    for msg in &connection.receiver {
        match msg {
            Message::Request(req) => {
                if connection.handle_shutdown(&req)? {
                    return Ok(());
                }
                handle_request(connection, req, &mut document_cache)?;
            }
            Message::Response(_resp) => {}
            Message::Notification(notifi) => {
                handle_notification(connection, notifi, &mut document_cache)?
            }
        }
    }
    Ok(())
}

fn handle_request(
    connection: &Connection,
    req: Request,
    document_cache: &mut DocumentCache,
) -> Result<(), Error> {
    let mut req = Some(req);
    if let Some((id, params)) = cast::<GotoDefinition>(&mut req) {
        let result = token_descr(
            document_cache,
            params.text_document_position_params.text_document,
            params.text_document_position_params.position,
        )
        .and_then(|token| goto_definition(document_cache, token));
        let resp = Response::new_ok(id, result);
        connection.sender.send(Message::Response(resp))?;
    } else if let Some((id, params)) = cast::<Completion>(&mut req) {
        let result = token_descr(
            document_cache,
            params.text_document_position.text_document,
            params.text_document_position.position,
        )
        .and_then(|token| completion::completion_at(document_cache, token));
        let resp = Response::new_ok(id, result);
        connection.sender.send(Message::Response(resp))?;
    } else if let Some((id, _params)) = cast::<HoverRequest>(&mut req) {
        /*let result =
            token_descr(document_cache, params.text_document_position_params).map(|x| Hover {
                contents: lsp_types::HoverContents::Scalar(MarkedString::from_language_code(
                    "text".into(),
                    format!("{:?}", x.token),
                )),
                range: None,
            });
        let resp = Response::new_ok(id, result);
        connection.sender.send(Message::Response(resp))?;*/
        connection.sender.send(Message::Response(Response::new_ok(id, None::<Hover>)))?;
    } else if let Some((id, params)) = cast::<CodeActionRequest>(&mut req) {
        let result = token_descr(document_cache, params.text_document, params.range.start)
            .and_then(|token| get_code_actions(document_cache, token.parent()));
        connection.sender.send(Message::Response(Response::new_ok(id, result)))?;
    } else if let Some((id, params)) = cast::<ExecuteCommand>(&mut req) {
        match params.command.as_str() {
            SHOW_PREVIEW_COMMAND => {
                show_preview_command(&params.arguments, connection, document_cache)?
            }
            _ => (),
        }
        connection
            .sender
            .send(Message::Response(Response::new_ok(id, None::<serde_json::Value>)))?;
    };
    Ok(())
}

fn cast<Kind: lsp_types::request::Request>(
    req: &mut Option<Request>,
) -> Option<(RequestId, Kind::Params)> {
    match req.take().unwrap().extract::<Kind::Params>(Kind::METHOD) {
        Ok(value) => Some(value),
        Err(owned) => {
            *req = Some(owned);
            None
        }
    }
}

fn handle_notification(
    connection: &Connection,
    req: lsp_server::Notification,
    document_cache: &mut DocumentCache,
) -> Result<(), Error> {
    match &*req.method {
        DidOpenTextDocument::METHOD => {
            let params: DidOpenTextDocumentParams = serde_json::from_value(req.params)?;
            reload_document(
                connection,
                params.text_document.text,
                params.text_document.uri,
                document_cache,
            )?;
        }
        DidChangeTextDocument::METHOD => {
            let mut params: DidChangeTextDocumentParams = serde_json::from_value(req.params)?;
            reload_document(
                connection,
                params.content_changes.pop().unwrap().text,
                params.text_document.uri,
                document_cache,
            )?;
        }
        "sixtyfps/showPreview" => {
            show_preview_command(
                req.params.as_array().map_or(&[], |x| x.as_slice()),
                connection,
                document_cache,
            )?;
        }
        _ => (),
    }
    Ok(())
}

fn show_preview_command(
    params: &[serde_json::Value],
    connection: &Connection,
    document_cache: &DocumentCache,
) -> Result<(), Error> {
    let e = || -> Error { "InvalidParameter".into() };
    let path = if let serde_json::Value::String(s) = params.get(0).ok_or_else(e)? {
        std::path::PathBuf::from(s)
    } else {
        return Err(e());
    };
    let path_canon = path.canonicalize().unwrap_or_else(|_| path.to_owned());
    let component = params.get(1).and_then(|v| v.as_str()).map(|v| v.to_string());
    let is_window = component
        .as_ref()
        .and_then(|c| {
            let mut ty = document_cache.documents.get_document(&path)?.local_registry.lookup(&c);
            while let Type::Component(c) = ty {
                ty = c.root_element.borrow().base_type.clone();
            }
            Some(matches!(ty, Type::Builtin(b) if b.name == "Window"))
        })
        .unwrap_or(false);
    preview::load_preview(
        connection.sender.clone(),
        preview::PreviewComponent { path: path_canon.into(), component, is_window },
        preview::PostLoadBehavior::ShowAfterLoad,
    );
    Ok(())
}

fn newline_offsets_from_content(content: &str) -> Vec<u32> {
    let mut ln_offs = 0;
    content
        .split('\n')
        .map(|line| {
            let r = ln_offs;
            ln_offs += line.len() as u32 + 1;
            r
        })
        .collect()
}

fn reload_document(
    connection: &Connection,
    content: String,
    uri: lsp_types::Url,
    document_cache: &mut DocumentCache,
) -> Result<(), Error> {
    let newline_offsets = newline_offsets_from_content(&content);
    document_cache.newline_offsets.insert(uri.clone(), newline_offsets);

    let path = uri.to_file_path().unwrap();
    let path_canon = path.canonicalize().unwrap_or_else(|_| path.to_owned());
    preview::set_contents(&path_canon, content.clone());
    let mut diag = BuildDiagnostics::default();
    spin_on::spin_on(document_cache.documents.load_file(&path_canon, &path, content, &mut diag));

    // Always provide diagnostics for all files. Empty diagnostics clear any previous ones.
    let mut lsp_diags: HashMap<Url, Vec<lsp_types::Diagnostic>> = core::iter::once(&path)
        .chain(diag.all_loaded_files.iter())
        .map(|path| {
            let uri = Url::from_file_path(path).unwrap();
            (uri, Default::default())
        })
        .collect();

    for d in diag.into_iter() {
        if d.source_file().unwrap().is_relative() {
            continue;
        }
        let uri = Url::from_file_path(d.source_file().unwrap()).unwrap();
        lsp_diags.entry(uri).or_default().push(to_lsp_diag(&d));
    }

    for (uri, diagnostics) in lsp_diags {
        connection.sender.send(Message::Notification(lsp_server::Notification::new(
            "textDocument/publishDiagnostics".into(),
            PublishDiagnosticsParams { uri, diagnostics, version: None },
        )))?;
    }

    Ok(())
}

fn to_lsp_diag_level(
    level: sixtyfps_compilerlib::diagnostics::DiagnosticLevel,
) -> lsp_types::DiagnosticSeverity {
    match level {
        sixtyfps_interpreter::DiagnosticLevel::Error => lsp_types::DiagnosticSeverity::Error,
        sixtyfps_interpreter::DiagnosticLevel::Warning => lsp_types::DiagnosticSeverity::Warning,
    }
}

fn to_lsp_diag(d: &sixtyfps_compilerlib::diagnostics::Diagnostic) -> lsp_types::Diagnostic {
    lsp_types::Diagnostic::new(
        to_range(d.line_column()),
        Some(to_lsp_diag_level(d.level())),
        None,
        None,
        d.message().to_owned(),
        None,
        None,
    )
}

fn to_range(span: (usize, usize)) -> Range {
    let pos = Position::new((span.0 as u32).saturating_sub(1), (span.1 as u32).saturating_sub(1));
    Range::new(pos, pos)
}

fn token_descr(
    document_cache: &mut DocumentCache,
    text_document: lsp_types::TextDocumentIdentifier,
    pos: Position,
) -> Option<SyntaxToken> {
    let o = document_cache.newline_offsets.get(&text_document.uri)?.get(pos.line as usize)?
        + pos.character as u32;

    let doc = document_cache.documents.get_document(&text_document.uri.to_file_path().ok()?)?;
    let node = doc.node.as_ref()?;
    if !node.text_range().contains(o.into()) {
        return None;
    }
    let mut taf = node.token_at_offset(o.into());
    let token = match (taf.next(), taf.next()) {
        (None, _) => return None,
        (Some(t), None) => t,
        (Some(l), Some(r)) => match (l.kind(), r.kind()) {
            // Prioritize identifier
            (SyntaxKind::Identifier, _) => l,
            (_, SyntaxKind::Identifier) => r,
            // then the dot
            (SyntaxKind::Dot, _) => l,
            (_, SyntaxKind::Dot) => r,
            // de-prioritize the white spaces
            (SyntaxKind::Whitespace, _) => r,
            (SyntaxKind::Comment, _) => r,
            (_, SyntaxKind::Whitespace) => l,
            (_, SyntaxKind::Comment) => l,
            _ => l,
        },
    };
    Some(SyntaxToken { token, source_file: node.source_file.clone() })
}

fn goto_definition(
    document_cache: &mut DocumentCache,
    token: SyntaxToken,
) -> Option<GotoDefinitionResponse> {
    let mut node = token.parent();
    loop {
        if let Some(n) = syntax_nodes::QualifiedName::new(node.clone()) {
            let parent = n.parent()?;
            let qual = sixtyfps_compilerlib::object_tree::QualifiedTypeName::from_node(n);
            return match parent.kind() {
                SyntaxKind::Element => {
                    let doc = document_cache.documents.get_document(node.source_file.path())?;
                    match doc.local_registry.lookup_qualified(&qual.members) {
                        sixtyfps_compilerlib::langtype::Type::Component(c) => {
                            goto_node(document_cache, &*c.root_element.borrow().node.as_ref()?)
                        }
                        _ => None,
                    }
                }
                _ => None,
            };
        } else if let Some(n) = syntax_nodes::ImportIdentifier::new(node.clone()) {
            let doc = document_cache.documents.get_document(node.source_file.path())?;
            let imp_name = sixtyfps_compilerlib::typeloader::ImportedName::from_node(n);
            return match doc.local_registry.lookup(&imp_name.internal_name) {
                sixtyfps_compilerlib::langtype::Type::Component(c) => {
                    goto_node(document_cache, &*c.root_element.borrow().node.as_ref()?)
                }
                _ => None,
            };
        } else if let Some(n) = syntax_nodes::ImportSpecifier::new(node.clone()) {
            let import_file = node
                .source_file
                .path()
                .parent()
                .unwrap_or(Path::new("/"))
                .join(n.child_text(SyntaxKind::StringLiteral)?.trim_matches('\"'));
            let import_file = import_file.canonicalize().unwrap_or(import_file);
            let doc = document_cache.documents.get_document(&import_file)?;
            let doc_node = doc.node.clone()?;
            return goto_node(document_cache, &*doc_node);
        } else if let Some(_) = syntax_nodes::BindingExpression::new(node.clone()) {
            // don't fallback to the Binding
            return None;
        } else if let Some(n) = syntax_nodes::Binding::new(node.clone()) {
            if token.kind() != SyntaxKind::Identifier {
                return None;
            }
            let prop_name = token.text();
            let element = syntax_nodes::Element::new(n.parent()?)?;
            if let Some(p) = element.PropertyDeclaration().find_map(|p| {
                (sixtyfps_compilerlib::parser::identifier_text(&p.DeclaredIdentifier())?
                    == prop_name)
                    .then(|| p)
            }) {
                return goto_node(document_cache, &p);
            }
            let n = find_property_declaration_in_base(&document_cache, element, prop_name)?;
            return goto_node(document_cache, &n);
        } else if let Some(n) = syntax_nodes::TwoWayBinding::new(node.clone()) {
            if token.kind() != SyntaxKind::Identifier {
                return None;
            }
            let prop_name = token.text();
            if prop_name != n.child_text(SyntaxKind::Identifier)? {
                return None;
            }
            let element = syntax_nodes::Element::new(n.parent()?)?;
            if let Some(p) = element.PropertyDeclaration().find_map(|p| {
                (sixtyfps_compilerlib::parser::identifier_text(&p.DeclaredIdentifier())?
                    == prop_name)
                    .then(|| p)
            }) {
                return goto_node(document_cache, &p);
            }
            let n = find_property_declaration_in_base(&document_cache, element, prop_name)?;
            return goto_node(document_cache, &n);
        } else if let Some(n) = syntax_nodes::CallbackConnection::new(node.clone()) {
            if token.kind() != SyntaxKind::Identifier {
                return None;
            }
            let prop_name = token.text();
            if prop_name != n.child_text(SyntaxKind::Identifier)? {
                return None;
            }
            let element = syntax_nodes::Element::new(n.parent()?)?;
            if let Some(p) = element.CallbackDeclaration().find_map(|p| {
                (sixtyfps_compilerlib::parser::identifier_text(&p.DeclaredIdentifier())?
                    == prop_name)
                    .then(|| p)
            }) {
                return goto_node(document_cache, &p);
            }
            let n = find_property_declaration_in_base(&document_cache, element, prop_name)?;
            return goto_node(document_cache, &n);
        }
        node = node.parent()?;
    }
}

/// Try to lookup the property `prop_name` in the base of the given Element
fn find_property_declaration_in_base(
    document_cache: &DocumentCache,
    element: syntax_nodes::Element,
    prop_name: &str,
) -> Option<SyntaxNode> {
    let global_tr = document_cache.documents.global_type_registry.borrow();
    let tr = element
        .source_file()
        .and_then(|sf| document_cache.documents.get_document(sf.path()))
        .map(|doc| &doc.local_registry)
        .unwrap_or(&global_tr);

    let mut element_type = lookup_current_element_type((*element).clone(), tr)?;
    while let Type::Component(com) = element_type {
        if let Some(p) = com.root_element.borrow().property_declarations.get(prop_name) {
            return p.type_node.clone();
        }
        element_type = com.root_element.borrow().base_type.clone();
    }
    None
}

fn goto_node(
    document_cache: &mut DocumentCache,
    node: &SyntaxNode,
) -> Option<GotoDefinitionResponse> {
    let path = node.source_file.path();
    let target_uri = Url::from_file_path(path).ok()?;
    let newline_offsets = match document_cache.newline_offsets.entry(target_uri.clone()) {
        std::collections::hash_map::Entry::Occupied(e) => e.into_mut(),
        std::collections::hash_map::Entry::Vacant(e) => {
            e.insert(newline_offsets_from_content(&std::fs::read_to_string(path).ok()?))
        }
    };
    let offset = node.span().offset as u32;
    let pos = newline_offsets.binary_search(&offset).map_or_else(
        |line| {
            if line == 0 {
                Position::new(0, offset)
            } else {
                Position::new(
                    line as u32 - 1,
                    newline_offsets.get(line - 1).map_or(0, |x| offset - *x),
                )
            }
        },
        |line| Position::new(line as u32, 0),
    );
    let range = Range::new(pos, pos);
    Some(GotoDefinitionResponse::Link(vec![LocationLink {
        origin_selection_range: None,
        target_uri,
        target_range: range,
        target_selection_range: range,
    }]))
}

fn get_code_actions(
    _document_cache: &mut DocumentCache,
    node: SyntaxNode,
) -> Option<Vec<CodeActionOrCommand>> {
    let component = syntax_nodes::Component::new(node.clone())
        .or_else(|| {
            syntax_nodes::DeclaredIdentifier::new(node.clone())
                .and_then(|n| n.parent())
                .and_then(|p| syntax_nodes::Component::new(p))
        })
        .or_else(|| {
            syntax_nodes::QualifiedName::new(node.clone())
                .and_then(|n| n.parent())
                .and_then(|p| syntax_nodes::Element::new(p))
                .and_then(|n| n.parent())
                .and_then(|p| syntax_nodes::Component::new(p))
        })?;

    let component_name =
        sixtyfps_compilerlib::parser::identifier_text(&component.DeclaredIdentifier())?;

    Some(vec![CodeActionOrCommand::Command(Command::new(
        "Show preview".into(),
        SHOW_PREVIEW_COMMAND.into(),
        Some(vec![component.source_file.path().to_string_lossy().into(), component_name.into()]),
    ))])
}

fn lookup_current_element_type(mut node: SyntaxNode, tr: &TypeRegister) -> Option<Type> {
    while node.kind() != SyntaxKind::Element {
        if let Some(parent) = node.parent() {
            node = parent
        } else {
            return None;
        }
    }
    let parent = node
        .parent()
        .and_then(|parent| lookup_current_element_type(parent, tr))
        .unwrap_or_default();
    let qualname = object_tree::QualifiedTypeName::from_node(
        syntax_nodes::Element::from(node).QualifiedName()?,
    );
    parent.lookup_type_for_child_element(&qualname.to_string(), tr).ok()
}