mod completion_item;
mod completion_context;

mod complete_dot;
mod complete_struct_literal;
mod complete_fn_param;
mod complete_keyword;
mod complete_snippet;
mod complete_path;
mod complete_scope;
mod complete_postfix;

use ra_db::SourceDatabase;
use ra_syntax::ast::{self, AstNode};

use crate::{
    db,
    FilePosition,
    completion::{
        completion_item::{Completions, CompletionKind},
        completion_context::CompletionContext,
    },
};

pub use crate::completion::completion_item::{CompletionItem, CompletionItemKind, InsertTextFormat};

/// Main entry point for completion. We run completion as a two-phase process.
///
/// First, we look at the position and collect a so-called `CompletionContext.
/// This is a somewhat messy process, because, during completion, syntax tree is
/// incomplete and can look really weird.
///
/// Once the context is collected, we run a series of completion routines which
/// look at the context and produce completion items. One subtlety about this
/// phase is that completion engine should not filter by the substring which is
/// already present, it should give all possible variants for the identifier at
/// the caret. In other words, for
///
/// ```no-run
/// fn f() {
///     let foo = 92;
///     let _ = bar<|>
/// }
/// ```
///
/// `foo` *should* be present among the completion variants. Filtering by
/// identifier prefix/fuzzy match should be done higher in the stack, together
/// with ordering of completions (currently this is done by the client).
pub(crate) fn completions(db: &db::RootDatabase, position: FilePosition) -> Option<Completions> {
    let original_file = db.parse(position.file_id);
    let ctx = CompletionContext::new(db, &original_file, position)?;

    let mut acc = Completions::default();

    complete_fn_param::complete_fn_param(&mut acc, &ctx);
    complete_keyword::complete_expr_keyword(&mut acc, &ctx);
    complete_keyword::complete_use_tree_keyword(&mut acc, &ctx);
    complete_snippet::complete_expr_snippet(&mut acc, &ctx);
    complete_snippet::complete_item_snippet(&mut acc, &ctx);
    complete_path::complete_path(&mut acc, &ctx);
    complete_scope::complete_scope(&mut acc, &ctx);
    complete_dot::complete_dot(&mut acc, &ctx);
    complete_struct_literal::complete_struct_literal(&mut acc, &ctx);
    complete_postfix::complete_postfix(&mut acc, &ctx);
    Some(acc)
}

pub fn function_label(node: &ast::FnDef) -> Option<String> {
    let label: String = if let Some(body) = node.body() {
        let body_range = body.syntax().range();
        let label: String = node
            .syntax()
            .children()
            .filter(|child| !child.range().is_subrange(&body_range)) // Filter out body
            .filter(|child| ast::Comment::cast(child).is_none()) // Filter out comments
            .filter(|child| ast::Attr::cast(child).is_none()) // Filter out attributes
            .map(|node| node.text().to_string())
            .collect();
        label
    } else {
        node.syntax().text().to_string()
    };

    Some(label.trim().to_owned())
}

pub fn const_label(node: &ast::ConstDef) -> String {
    let label: String = node
        .syntax()
        .children()
        .filter(|child| ast::Comment::cast(child).is_none())
        .filter(|child| ast::Attr::cast(child).is_none())
        .map(|node| node.text().to_string())
        .collect();

    label.trim().to_owned()
}

pub fn type_label(node: &ast::TypeDef) -> String {
    let label: String = node
        .syntax()
        .children()
        .filter(|child| ast::Comment::cast(child).is_none())
        .filter(|child| ast::Attr::cast(child).is_none())
        .map(|node| node.text().to_string())
        .collect();

    label.trim().to_owned()
}