#[cfg(test)]
mod tests;

use avril_core::ModuleLoader;
use avril_lsp::{Documents, ProjectInput, ProjectService, Refresh, ScriptKind, Source};
use avril_runtime::{caps::Capabilities, registry::Options};
use notify::Watcher;
use serde_json::json;
use std::{
    collections::{BTreeMap, BTreeSet},
    path::{Path, PathBuf},
    sync::{
        Arc, Mutex,
        atomic::{AtomicBool, Ordering},
    },
};

use crate::cli::ParseError;
use crate::fragments::{Arg, reject};

struct LiveProject {
    root: PathBuf,
    caps: Arc<Capabilities>,
    options: Options,
    explicit_lock: bool,
    automatic_types: bool,
    dirty: Arc<AtomicBool>,
    rewatch: Arc<AtomicBool>,
    watcher: Option<notify::RecommendedWatcher>,
    watched: BTreeMap<PathBuf, bool>,
    tracked_config: Arc<Mutex<BTreeSet<PathBuf>>>,
}
impl LiveProject {
    fn watch(&mut self, path: &Path, recursive: bool) {
        let Some(watcher) = &mut self.watcher else {
            return;
        };
        if self
            .watched
            .get(path)
            .is_some_and(|current| *current || !recursive)
            || self
                .watched
                .iter()
                .any(|(root, recursive)| *recursive && path.starts_with(root))
        {
            return;
        }
        if watcher
            .watch(
                path,
                if recursive {
                    notify::RecursiveMode::Recursive
                } else {
                    notify::RecursiveMode::NonRecursive
                },
            )
            .is_ok()
        {
            self.watched.insert(path.to_owned(), recursive);
        }
    }
}
impl ProjectService for LiveProject {
    fn changed(&mut self) -> bool {
        let dirty = self.dirty.swap(false, Ordering::AcqRel);
        if self.rewatch.swap(false, Ordering::AcqRel) {
            // A watch follows an inode, not a directory recreated at the same path.
            for (path, recursive) in std::mem::take(&mut self.watched) {
                if let Some(watcher) = &mut self.watcher {
                    let _ = watcher.unwatch(&path);
                }
                self.watch(&path, recursive);
            }
        }
        dirty
    }
    fn refresh(&mut self, documents: Documents) -> Refresh<'_> {
        Box::pin(async move { self.input(documents, &[]).await })
    }
}

impl LiveProject {
    fn input(&mut self, documents: Documents, extra_roots: &[String]) -> Refresh<'_> {
        let extra_roots = extra_roots.to_vec();
        Box::pin(async move {
            if self.caps.unrestricted_js_exec() {
                self.watch(&self.root.clone(), true);
            }
            let authority = avril_runtime::authority::SourceAuthority::execute(self.caps.clone());
            let anchor = self.root.join(".avril-lsp.js");
            // Broken configs are reported on their modules by the type collector;
            // they must not prevent unrelated open documents from being checked.
            let root = avril_runtime::modules::ModuleGraph::project_root_for_repl(
                &authority,
                anchor.to_str().ok_or("Project path must be UTF-8")?,
            )
            .unwrap_or_else(|_| self.root.clone());
            let mut options = self.options.clone();
            if !self.explicit_lock {
                options.lock = root.join("avril.lock");
            }
            let lock_path = options.lock.clone();
            options.project_root = root.clone();
            if self.caps.unrestricted_js_exec() {
                if let Some(parent) = options.lock.ancestors().skip(1).find(|p| p.is_dir()) {
                    self.watch(parent, false);
                }
                if let Some(vendor) = &options.vendor {
                    self.watch(vendor, true);
                }
            }
            let discovered = if extra_roots.is_empty() && self.caps.unrestricted_js_exec() {
                let workspace = self.root.clone();
                let cache = options.cache.clone();
                let vendor = options.vendor.clone();
                tokio::task::spawn_blocking(move || -> avril_lsp::Result<Vec<String>> {
                    let mut sources = Vec::new();
                    for entry in ignore::WalkBuilder::new(workspace)
                        .require_git(false)
                        .filter_entry(move |entry| {
                            entry.path() != cache
                                && vendor.as_ref().is_none_or(|path| entry.path() != path)
                                && entry.file_name() != "node_modules"
                        })
                        .build()
                    {
                        let entry = entry?;
                        if entry.file_type().is_some_and(|kind| kind.is_file())
                            && matches!(
                                entry.path().extension().and_then(|s| s.to_str()),
                                Some("ts" | "tsx" | "js" | "jsx" | "mts" | "cts" | "mjs" | "cjs")
                            )
                        {
                            sources.push(
                                entry
                                    .path()
                                    .to_str()
                                    .ok_or("Module path must be UTF-8")?
                                    .to_owned(),
                            );
                        }
                    }
                    sources.sort();
                    Ok(sources)
                })
                .await??
            } else {
                Vec::new()
            };
            let graph = avril_runtime::modules::ModuleGraph::open(
                tokio::runtime::Handle::current(),
                authority,
                options,
            )?;
            graph.set_automatic_types(self.automatic_types);
            graph.set_typescript_version(avril_lsp::BACKEND_VERSION)?;
            let mut overlays = BTreeMap::new();
            for (uri, text) in documents {
                let path = url::Url::parse(&uri)?
                    .to_file_path()
                    .map_err(|_| "Only local source documents can be edited")?;
                overlays.insert(
                    path.to_str().ok_or("Module path must be UTF-8")?.to_owned(),
                    text,
                );
            }
            let mut roots: Vec<_> = overlays.keys().cloned().collect();
            roots.extend(extra_roots.iter().cloned());
            roots.extend(discovered);
            let types = graph.type_graph(&roots, &overlays).await?;
            let mut tracked = types.config_inputs.clone();
            tracked.insert(lock_path);
            tracked.extend(
                types
                    .sources
                    .keys()
                    .filter(|name| graph.is_workspace_source(name))
                    .map(PathBuf::from),
            );
            *self.tracked_config.lock().unwrap() = tracked;
            let uri = |name: &str| -> avril_lsp::Result<String> {
                avril_lsp::canonical_uri(&graph.module_url(name).ok_or("Invalid module identity")?)
            };
            let mut input = ProjectInput {
                script_kinds: BTreeMap::new(),
                sources: crate::stdlib::declarations()
                    .map(|(name, text)| Source {
                        uri: format!("avril:/runtime/stdlib/{name}"),
                        text: text.into(),
                        read_only: true,
                    })
                    .collect(),
                // Dynamic import must remain import-mode even in CommonJS files.
                compiler_options: json!({"strict":true,"noEmit":true,"skipLibCheck":true,"target":"esnext","module":"preserve","moduleResolution":"bundler","moduleDetection":"force","allowImportingTsExtensions":true,"allowJs":true,"types":[],"jsx":"react-jsx"}),
                imports: BTreeMap::new(),
                import_candidates: Vec::new(),
                per_file_options: BTreeMap::new(),
                diagnostics: BTreeMap::new(),
                type_references: BTreeMap::new(),
                path_references: BTreeMap::new(),
                globals: BTreeSet::new(),
            };
            if self.caps.unrestricted_js_exec() {
                for path in &types.config_inputs {
                    if let Some(parent) = path.ancestors().skip(1).find(|p| p.is_dir()) {
                        self.watch(parent, false);
                    }
                }
            }
            for (name, text) in &types.sources {
                let identity = uri(name)?;
                let local = graph.is_workspace_source(name);
                if avril_runtime::modules::data_url(name).is_some() {
                    let kind = if types.source_types[name].is_typescript() {
                        ScriptKind::TypeScript
                    } else {
                        ScriptKind::JavaScript
                    };
                    input.script_kinds.insert(identity.clone(), kind);
                }
                input.sources.push(Source {
                    uri: identity.clone(),
                    text: text.clone(),
                    read_only: !local,
                });
                if let Some(options) = types.compiler_options.get(name) {
                    input.per_file_options.insert(identity, json!(options));
                }
                if local && self.caps.unrestricted_js_exec() {
                    // Parent watches detect new/moved configs as well as source changes.
                    for parent in Path::new(name).ancestors().skip(1) {
                        self.watch(parent, false);
                    }
                }
            }
            for (name, imports) in &types.edges {
                for ((mode, specifier), target) in imports {
                    if target.starts_with("avril:") {
                        continue;
                    } // Ambient builtin declarations.
                    let mut target = target;
                    let mut seen = BTreeSet::new();
                    while let Some(next) = types.redirects.get(target) {
                        if !seen.insert(target) || !types.sources.contains_key(next) {
                            break;
                        }
                        target = next;
                    }
                    if types.sources.contains_key(target) {
                        let targets = input
                            .imports
                            .entry((uri(name)?, specifier.clone()))
                            .or_default();
                        if mode.is_require() {
                            targets.require = Some(uri(target)?);
                        } else {
                            targets.import = Some(uri(target)?);
                        }
                    }
                }
            }
            for (name, errors) in &types.unresolved {
                for (specifier, error) in errors {
                    input
                        .diagnostics
                        .entry(uri(name)?)
                        .or_default()
                        .push(format!("{specifier}: {error}"));
                }
            }
            for errors in [
                &types.unavailable,
                &types.package_errors,
                &types.compiler_errors,
            ] {
                for (name, error) in errors {
                    input
                        .diagnostics
                        .entry(uri(name)?)
                        .or_default()
                        .push(error.clone());
                }
            }
            input.globals = types
                .globals
                .iter()
                .filter(|name| types.sources.contains_key(*name))
                .map(|name| uri(name))
                .collect::<avril_lsp::Result<_>>()?;
            for (references, targets) in [
                (&types.type_references, &mut input.type_references),
                (&types.path_references, &mut input.path_references),
            ] {
                for ((name, reference), target) in references {
                    if types.sources.contains_key(target) {
                        targets.insert((uri(name)?, reference.clone()), uri(target)?);
                    }
                }
            }
            for ((from, specifier), target) in
                graph.type_import_candidates(&types, overlays.keys()).await
            {
                input
                    .import_candidates
                    .push((uri(&from)?, uri(&target)?, specifier));
            }
            // Acquisition may populate the cache, but editor refreshes never write locks,
            // snapshots, tsconfig files, or application sources.
            Ok(input)
        })
    }
}

/// Builds the type-checking generation for one on-disk entry module, without
/// editor overlays or filesystem watches.
pub(crate) async fn check_input(
    root: PathBuf,
    caps: Arc<Capabilities>,
    options: Options,
    explicit_lock: bool,
    automatic_types: bool,
    entry: &str,
) -> avril_lsp::Result<ProjectInput> {
    let mut project = LiveProject {
        root,
        caps,
        options,
        explicit_lock,
        automatic_types,
        dirty: Arc::new(AtomicBool::new(false)),
        rewatch: Arc::new(AtomicBool::new(false)),
        watcher: None,
        watched: BTreeMap::new(),
        tracked_config: Arc::new(Mutex::new(BTreeSet::new())),
    };
    project.input(BTreeMap::new(), &[entry.to_owned()]).await
}

pub struct Args {
    pub typescript: PathBuf,
    pub project: Option<String>,
    pub entry: crate::fragments::Entry,
}

/// `avril lsp` argument parsing failed.
#[derive(Debug, thiserror::Error)]
pub enum LspParseError {
    #[error(transparent)]
    Generic(#[from] ParseError),
    #[error("lsp requires --typescript=PATH to the native backend")]
    MissingBackend,
}

pub fn parse(args: &[String]) -> std::result::Result<Args, LspParseError> {
    let cwd = crate::fragments::working_dir()?;
    let mut parser = crate::fragments::Parser::new("lsp", args.to_vec(), &cwd)?;
    let (mut typescript, mut project) = (None, None);
    while let Some(arg) = parser.next()? {
        match arg {
            Arg::Positional(arg) => parser.command.check(&arg).map_err(ParseError::Check)?,
            Arg::Flag(arg) if parser.path_once(&arg, "--typescript", &mut typescript)? => {}
            Arg::Flag(arg) if parser.path_once(&arg, "--project", &mut project)? => {}
            Arg::Flag(arg) => return Err(reject(&arg, &[]).into()),
        }
    }
    let typescript = typescript.ok_or(LspParseError::MissingBackend)?;
    // The language server takes no entry module: open documents are the roots.
    let entry = parser.synthetic(".avril-lsp.js")?;
    Ok(Args {
        typescript: PathBuf::from(typescript),
        project,
        entry,
    })
}

pub fn run(args: Args) -> Result<(), Box<dyn std::error::Error>> {
    let Args {
        typescript: binary,
        project,
        entry,
    } = args;
    let root = std::fs::canonicalize(project.as_deref().unwrap_or("."))?;
    if !root.is_dir() {
        return Err("--project must name a workspace directory".into());
    }
    let dirty = Arc::new(AtomicBool::new(false));
    let rewatch = Arc::new(AtomicBool::new(false));
    let tracked_config = Arc::new(Mutex::new(BTreeSet::<PathBuf>::new()));
    let mut ignore_builder = ignore::gitignore::GitignoreBuilder::new(&root);
    let _ = ignore_builder.add(root.join(".gitignore"));
    let _ = ignore_builder.add(root.join(".ignore"));
    let ignored = ignore_builder.build()?;
    let watcher = notify::recommended_watcher({
        let dirty = dirty.clone();
        let rewatch = rewatch.clone();
        let cache =
            avril_runtime::caps::PathTarget::for_creation(&entry.packages.cache)?.into_path();
        let tracked_config = tracked_config.clone();
        let root = root.clone();
        let mut ignored = ignored.clone();
        move |event: notify::Result<notify::Event>| {
            // Cache acquisition is an output of refreshing, not an input change.
            // Watch directories coarsely so arbitrary extends/lock filenames and
            // missing-file creation or directory renames cannot leave stale graphs.
            if event.map_or(true, |e| {
                // Reading ignore rules generates access events of its own.
                if matches!(e.kind, notify::EventKind::Access(_)) && !e.need_rescan() {
                    return false;
                }
                let configs = tracked_config.lock().unwrap();
                if e.paths
                    .iter()
                    .any(|path| path == &root.join(".gitignore") || path == &root.join(".ignore"))
                {
                    let mut builder = ignore::gitignore::GitignoreBuilder::new(&root);
                    let _ = builder.add(root.join(".gitignore"));
                    let _ = builder.add(root.join(".ignore"));
                    if let Ok(updated) = builder.build() {
                        ignored = updated;
                    }
                }
                let relevant = e.need_rescan()
                    || e.paths.iter().any(|path| {
                        if configs.contains(path) {
                            return true;
                        }
                        if path.starts_with(&cache)
                            || (path.starts_with(&root)
                                && ignored
                                    .matched_path_or_any_parents(path, path.is_dir())
                                    .is_ignore())
                            || path.strip_prefix(&root).unwrap_or(path).components().any(
                                |component| {
                                    matches!(
                                        component.as_os_str().to_str(),
                                        Some(".git" | ".jj" | ".hg" | ".svn" | "node_modules")
                                    )
                                },
                            )
                        {
                            return false;
                        }
                        if path.starts_with(root.join(".avril").join("npm")) {
                            return false;
                        }
                        let directory_event = matches!(
                            e.kind,
                            notify::EventKind::Create(notify::event::CreateKind::Folder)
                                | notify::EventKind::Remove(notify::event::RemoveKind::Folder)
                                | notify::EventKind::Modify(notify::event::ModifyKind::Name(_))
                        );
                        if directory_event
                            && (path.starts_with(&root)
                                || configs.iter().any(|config| config.starts_with(path)))
                        {
                            return true;
                        }
                        let name = path
                            .file_name()
                            .and_then(|name| name.to_str())
                            .unwrap_or_default();
                        if !path.starts_with(&root) {
                            return false;
                        }
                        if matches!(
                            name,
                            "package.json" | "avril.conf" | "avril.lock" | ".gitignore" | ".ignore"
                        ) || name.starts_with("tsconfig")
                        {
                            return true;
                        }
                        matches!(
                            path.extension().and_then(|extension| extension.to_str()),
                            Some("ts" | "tsx" | "js" | "jsx" | "mts" | "cts" | "mjs" | "cjs")
                        )
                    });
                if relevant
                    && (e.need_rescan()
                        || matches!(
                            e.kind,
                            notify::EventKind::Remove(notify::event::RemoveKind::Folder)
                                | notify::EventKind::Modify(notify::event::ModifyKind::Name(_))
                        ))
                {
                    rewatch.store(true, Ordering::Release);
                }
                relevant
            }) {
                dirty.store(true, Ordering::Release);
            }
        }
    })?;
    let mut service = LiveProject {
        root: root.clone(),
        caps: entry.caps,
        options: entry.packages,
        explicit_lock: entry.explicit_lock,
        automatic_types: entry.automatic_types,
        dirty,
        rewatch,
        watcher: Some(watcher),
        watched: BTreeMap::new(),
        tracked_config,
    };
    if service.caps.unrestricted_js_exec() {
        service.watch(&root, true);
    }
    let runtime = tokio::runtime::Builder::new_multi_thread()
        .worker_threads(2)
        .enable_all()
        .build()?;
    let result = runtime.block_on(avril_lsp::serve(
        tokio::io::stdin(),
        tokio::io::stdout(),
        binary,
        Box::new(service),
    ));
    // An editor can send exit without closing stdin; its blocking read cannot
    // be cancelled. Backend teardown is independent of that read.
    runtime.shutdown_background();
    result.map_err(|e| -> Box<dyn std::error::Error> { e })
}