//! FIXME: write short doc here

use std::{panic, sync::Arc};

use hir_def::{db::DefDatabase2, ModuleId};
use hir_expand::diagnostics::DiagnosticSink;
use parking_lot::Mutex;
use ra_cfg::CfgOptions;
use ra_db::{
    salsa, CrateGraph, CrateId, Edition, FileId, FileLoader, FileLoaderDelegate, RelativePath,
    RelativePathBuf, SourceDatabase, SourceDatabaseExt, SourceRoot, SourceRootId,
};
use rustc_hash::FxHashMap;

use crate::{db, debug::HirDebugHelper};

pub const WORKSPACE: SourceRootId = SourceRootId(0);

#[salsa::database(
    ra_db::SourceDatabaseExtStorage,
    ra_db::SourceDatabaseStorage,
    db::InternDatabaseStorage,
    db::AstDatabaseStorage,
    db::DefDatabaseStorage,
    db::DefDatabase2Storage,
    db::HirDatabaseStorage
)]
#[derive(Debug)]
pub struct MockDatabase {
    events: Mutex<Option<Vec<salsa::Event<MockDatabase>>>>,
    runtime: salsa::Runtime<MockDatabase>,
    files: FxHashMap<String, FileId>,
    crate_names: Arc<FxHashMap<CrateId, String>>,
    file_paths: Arc<FxHashMap<FileId, String>>,
}

impl panic::RefUnwindSafe for MockDatabase {}

impl FileLoader for MockDatabase {
    fn file_text(&self, file_id: FileId) -> Arc<String> {
        FileLoaderDelegate(self).file_text(file_id)
    }
    fn resolve_relative_path(
        &self,
        anchor: FileId,
        relative_path: &RelativePath,
    ) -> Option<FileId> {
        FileLoaderDelegate(self).resolve_relative_path(anchor, relative_path)
    }
    fn relevant_crates(&self, file_id: FileId) -> Arc<Vec<CrateId>> {
        FileLoaderDelegate(self).relevant_crates(file_id)
    }
}

impl HirDebugHelper for MockDatabase {
    fn crate_name(&self, krate: CrateId) -> Option<String> {
        self.crate_names.get(&krate).cloned()
    }

    fn file_path(&self, file_id: FileId) -> Option<String> {
        self.file_paths.get(&file_id).cloned()
    }
}

impl MockDatabase {
    pub fn with_single_file(text: &str) -> (MockDatabase, SourceRoot, FileId) {
        let mut db = MockDatabase::default();
        let mut source_root = SourceRoot::default();
        let file_id = db.add_file(WORKSPACE, "/", &mut source_root, "/main.rs", text);
        db.set_source_root(WORKSPACE, Arc::new(source_root.clone()));
        (db, source_root, file_id)
    }

    pub fn file_id_of(&self, path: &str) -> FileId {
        match self.files.get(path) {
            Some(it) => *it,
            None => panic!("unknown file: {:?}\nexisting files:\n{:#?}", path, self.files),
        }
    }

    pub fn diagnostics(&self) -> String {
        let mut buf = String::new();
        let crate_graph = self.crate_graph();
        for krate in crate_graph.iter().next() {
            let crate_def_map = self.crate_def_map(krate);
            for (module_id, _) in crate_def_map.modules.iter() {
                let module_id = ModuleId { krate, module_id };
                let module = crate::Module::from(module_id);
                module.diagnostics(
                    self,
                    &mut DiagnosticSink::new(|d| {
                        buf += &format!("{:?}: {}\n", d.syntax_node(self).text(), d.message());
                    }),
                )
            }
        }
        buf
    }

    fn add_file(
        &mut self,
        source_root_id: SourceRootId,
        source_root_prefix: &str,
        source_root: &mut SourceRoot,
        path: &str,
        text: &str,
    ) -> FileId {
        assert!(source_root_prefix.starts_with('/'));
        assert!(source_root_prefix.ends_with('/'));
        assert!(path.starts_with(source_root_prefix));
        let rel_path = RelativePathBuf::from_path(&path[source_root_prefix.len()..]).unwrap();

        let is_crate_root = rel_path == "lib.rs" || rel_path == "/main.rs";

        let file_id = FileId(self.files.len() as u32);

        let prev = self.files.insert(path.to_string(), file_id);
        assert!(prev.is_none(), "duplicate files in the text fixture");
        Arc::make_mut(&mut self.file_paths).insert(file_id, path.to_string());

        let text = Arc::new(text.to_string());
        self.set_file_text(file_id, text);
        self.set_file_relative_path(file_id, rel_path.clone());
        self.set_file_source_root(file_id, source_root_id);
        source_root.insert_file(rel_path, file_id);

        if is_crate_root {
            let mut crate_graph = CrateGraph::default();
            crate_graph.add_crate_root(file_id, Edition::Edition2018, CfgOptions::default());
            self.set_crate_graph(Arc::new(crate_graph));
        }
        file_id
    }
}

impl salsa::Database for MockDatabase {
    fn salsa_runtime(&self) -> &salsa::Runtime<MockDatabase> {
        &self.runtime
    }

    fn salsa_event(&self, event: impl Fn() -> salsa::Event<MockDatabase>) {
        let mut events = self.events.lock();
        if let Some(events) = &mut *events {
            events.push(event());
        }
    }
}

impl Default for MockDatabase {
    fn default() -> MockDatabase {
        let mut db = MockDatabase {
            events: Default::default(),
            runtime: salsa::Runtime::default(),
            files: FxHashMap::default(),
            crate_names: Default::default(),
            file_paths: Default::default(),
        };
        db.set_crate_graph(Default::default());
        db
    }
}

impl salsa::ParallelDatabase for MockDatabase {
    fn snapshot(&self) -> salsa::Snapshot<MockDatabase> {
        salsa::Snapshot::new(MockDatabase {
            events: Default::default(),
            runtime: self.runtime.snapshot(self),
            // only the root database can be used to get file_id by path.
            files: FxHashMap::default(),
            file_paths: Arc::clone(&self.file_paths),
            crate_names: Arc::clone(&self.crate_names),
        })
    }
}

impl MockDatabase {
    pub fn log(&self, f: impl FnOnce()) -> Vec<salsa::Event<MockDatabase>> {
        *self.events.lock() = Some(Vec::new());
        f();
        self.events.lock().take().unwrap()
    }

    pub fn log_executed(&self, f: impl FnOnce()) -> Vec<String> {
        let events = self.log(f);
        events
            .into_iter()
            .filter_map(|e| match e.kind {
                // This pretty horrible, but `Debug` is the only way to inspect
                // QueryDescriptor at the moment.
                salsa::EventKind::WillExecute { database_key } => {
                    Some(format!("{:?}", database_key))
                }
                _ => None,
            })
            .collect()
    }
}