//! FIXME: write short doc here

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

use parking_lot::Mutex;
use ra_cfg::CfgOptions;
use ra_db::{
    salsa, CrateGraph, CrateId, Edition, FileId, FileLoader, FileLoaderDelegate, FilePosition,
    SourceDatabase, SourceDatabaseExt, SourceRoot, SourceRootId,
};
use relative_path::{RelativePath, RelativePathBuf};
use rustc_hash::FxHashMap;
use test_utils::{extract_offset, parse_fixture, CURSOR_MARKER};

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

pub const WORKSPACE: SourceRootId = SourceRootId(0);

#[salsa::database(
    hir_def::db::DefDatabase2Storage,
    ra_db::SourceDatabaseExtStorage,
    ra_db::SourceDatabaseStorage,
    db::InternDatabaseStorage,
    db::AstDatabaseStorage,
    db::DefDatabaseStorage,
    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_files(fixture: &str) -> MockDatabase {
        let (db, position) = MockDatabase::from_fixture(fixture);
        assert!(position.is_none());
        db
    }

    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 with_position(fixture: &str) -> (MockDatabase, FilePosition) {
        let (db, position) = MockDatabase::from_fixture(fixture);
        let position = position.expect("expected a marker ( <|> )");
        (db, position)
    }

    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 set_crate_graph_from_fixture(&mut self, graph: CrateGraphFixture) {
        let mut ids = FxHashMap::default();
        let mut crate_graph = CrateGraph::default();
        for (crate_name, (crate_root, edition, cfg_options, _)) in graph.0.iter() {
            let crate_root = self.file_id_of(&crate_root);
            let crate_id = crate_graph.add_crate_root(crate_root, *edition, cfg_options.clone());
            Arc::make_mut(&mut self.crate_names).insert(crate_id, crate_name.clone());
            ids.insert(crate_name, crate_id);
        }
        for (crate_name, (_, _, _, deps)) in graph.0.iter() {
            let from = ids[crate_name];
            for dep in deps {
                let to = ids[dep];
                crate_graph.add_dep(from, dep.as_str().into(), to).unwrap();
            }
        }
        self.set_crate_graph(Arc::new(crate_graph))
    }

    pub fn diagnostics(&self) -> String {
        let mut buf = String::new();
        let mut files: Vec<FileId> = self.files.values().copied().collect();
        files.sort();
        for file in files {
            let src = crate::Source {
                file_id: file.into(),
                ast: crate::ModuleSource::new(self, Some(file), None),
            };
            let module = crate::Module::from_definition(self, src).unwrap();
            module.diagnostics(
                self,
                &mut DiagnosticSink::new(|d| {
                    buf += &format!("{:?}: {}\n", d.syntax_node(self).text(), d.message());
                }),
            )
        }
        buf
    }

    fn from_fixture(fixture: &str) -> (MockDatabase, Option<FilePosition>) {
        let mut db = MockDatabase::default();

        let pos = db.add_fixture(fixture);

        (db, pos)
    }

    fn add_fixture(&mut self, fixture: &str) -> Option<FilePosition> {
        let mut position = None;
        let mut source_root = SourceRoot::default();
        let mut source_root_id = WORKSPACE;
        let mut source_root_prefix = "/".to_string();
        for entry in parse_fixture(fixture) {
            if entry.meta.starts_with("root") {
                self.set_source_root(source_root_id, Arc::new(source_root));
                source_root = SourceRoot::default();

                source_root_id = SourceRootId(source_root_id.0 + 1);
                source_root_prefix = entry.meta["root".len()..].trim().to_string();
                continue;
            }
            if entry.text.contains(CURSOR_MARKER) {
                assert!(position.is_none(), "only one marker (<|>) per fixture is allowed");
                position = Some(self.add_file_with_position(
                    source_root_id,
                    &source_root_prefix,
                    &mut source_root,
                    &entry.meta,
                    &entry.text,
                ));
            } else {
                self.add_file(
                    source_root_id,
                    &source_root_prefix,
                    &mut source_root,
                    &entry.meta,
                    &entry.text,
                );
            }
        }
        self.set_source_root(source_root_id, Arc::new(source_root));
        position
    }

    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
    }

    fn add_file_with_position(
        &mut self,
        source_root_id: SourceRootId,
        source_root_prefix: &str,
        source_root: &mut SourceRoot,
        path: &str,
        text: &str,
    ) -> FilePosition {
        let (offset, text) = extract_offset(text);
        let file_id = self.add_file(source_root_id, source_root_prefix, source_root, path, &text);
        FilePosition { file_id, offset }
    }
}

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()
    }
}

#[derive(Default)]
pub struct CrateGraphFixture(pub Vec<(String, (String, Edition, CfgOptions, Vec<String>))>);

#[macro_export]
macro_rules! crate_graph {
    ($(
        $crate_name:literal: (
            $crate_path:literal,
            $($edition:literal,)?
            [$($dep:literal),*]
            $(, cfg = {
                $($key:literal $(= $value:literal)?),*
                $(,)?
            })?
        ),
    )*) => {{
        let mut res = $crate::mock::CrateGraphFixture::default();
        $(
            #[allow(unused_mut, unused_assignments)]
            let mut edition = ra_db::Edition::Edition2018;
            $(edition = ra_db::Edition::from_string($edition);)?
            let cfg_options = {
                #[allow(unused_mut)]
                let mut cfg = ::ra_cfg::CfgOptions::default();
                $(
                    $(
                        if 0 == 0 $(+ { drop($value); 1})? {
                            cfg.insert_atom($key.into());
                        }
                        $(cfg.insert_key_value($key.into(), $value.into());)?
                    )*
                )?
                cfg
            };
            res.0.push((
                $crate_name.to_string(),
                ($crate_path.to_string(), edition, cfg_options, vec![$($dep.to_string()),*])
            ));
        )*
        res
    }}
}