//! Defines database & queries for macro expansion.

use std::sync::Arc;

use mbe::MacroRules;
use ra_db::{salsa, SourceDatabase};
use ra_prof::profile;
use ra_syntax::{AstNode, Parse, SyntaxNode};

use crate::{
    ast_id_map::AstIdMap, HirFileId, HirFileIdRepr, MacroCallId, MacroCallLoc, MacroDefId,
    MacroFile, MacroFileKind,
};

// FIXME: rename to ExpandDatabase
#[salsa::query_group(AstDatabaseStorage)]
pub trait AstDatabase: SourceDatabase {
    fn ast_id_map(&self, file_id: HirFileId) -> Arc<AstIdMap>;

    #[salsa::transparent]
    fn parse_or_expand(&self, file_id: HirFileId) -> Option<SyntaxNode>;

    #[salsa::interned]
    fn intern_macro(&self, macro_call: MacroCallLoc) -> MacroCallId;
    fn macro_arg(&self, id: MacroCallId) -> Option<Arc<tt::Subtree>>;
    fn macro_def(&self, id: MacroDefId) -> Option<Arc<mbe::MacroRules>>;
    fn parse_macro(&self, macro_file: MacroFile) -> Option<Parse<SyntaxNode>>;
    fn macro_expand(&self, macro_call: MacroCallId) -> Result<Arc<tt::Subtree>, String>;
}

pub(crate) fn ast_id_map(db: &dyn AstDatabase, file_id: HirFileId) -> Arc<AstIdMap> {
    let map =
        db.parse_or_expand(file_id).map_or_else(AstIdMap::default, |it| AstIdMap::from_source(&it));
    Arc::new(map)
}

pub(crate) fn macro_def(db: &dyn AstDatabase, id: MacroDefId) -> Option<Arc<MacroRules>> {
    let macro_call = id.ast_id.to_node(db);
    let arg = macro_call.token_tree()?;
    let (tt, _) = mbe::ast_to_token_tree(&arg).or_else(|| {
        log::warn!("fail on macro_def to token tree: {:#?}", arg);
        None
    })?;
    let rules = MacroRules::parse(&tt).ok().or_else(|| {
        log::warn!("fail on macro_def parse: {:#?}", tt);
        None
    })?;
    Some(Arc::new(rules))
}

pub(crate) fn macro_arg(db: &dyn AstDatabase, id: MacroCallId) -> Option<Arc<tt::Subtree>> {
    let loc = db.lookup_intern_macro(id);
    let macro_call = loc.ast_id.to_node(db);
    let arg = macro_call.token_tree()?;
    let (tt, _) = mbe::ast_to_token_tree(&arg)?;
    Some(Arc::new(tt))
}

pub(crate) fn macro_expand(
    db: &dyn AstDatabase,
    id: MacroCallId,
) -> Result<Arc<tt::Subtree>, String> {
    let loc = db.lookup_intern_macro(id);
    let macro_arg = db.macro_arg(id).ok_or("Fail to args in to tt::TokenTree")?;

    let macro_rules = db.macro_def(loc.def).ok_or("Fail to find macro definition")?;
    let tt = macro_rules.expand(&macro_arg).map_err(|err| format!("{:?}", err))?;
    // Set a hard limit for the expanded tt
    let count = tt.count();
    if count > 65536 {
        return Err(format!("Total tokens count exceed limit : count = {}", count));
    }
    Ok(Arc::new(tt))
}

pub(crate) fn parse_or_expand(db: &dyn AstDatabase, file_id: HirFileId) -> Option<SyntaxNode> {
    match file_id.0 {
        HirFileIdRepr::FileId(file_id) => Some(db.parse(file_id).tree().syntax().clone()),
        HirFileIdRepr::MacroFile(macro_file) => {
            db.parse_macro(macro_file).map(|it| it.syntax_node())
        }
    }
}

pub(crate) fn parse_macro(
    db: &dyn AstDatabase,
    macro_file: MacroFile,
) -> Option<Parse<SyntaxNode>> {
    let _p = profile("parse_macro_query");
    let macro_call_id = macro_file.macro_call_id;
    let tt = db
        .macro_expand(macro_call_id)
        .map_err(|err| {
            // Note:
            // The final goal we would like to make all parse_macro success,
            // such that the following log will not call anyway.
            log::warn!("fail on macro_parse: (reason: {})", err,);
        })
        .ok()?;
    match macro_file.macro_file_kind {
        MacroFileKind::Items => mbe::token_tree_to_items(&tt).ok().map(Parse::to_syntax),
        MacroFileKind::Expr => mbe::token_tree_to_expr(&tt).ok().map(Parse::to_syntax),
    }
}