// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

// Namespace Handling.

use super::utils::{DIB, debug_context};

use llvm;
use llvm::debuginfo::DIScope;
use rustc::middle::def_id::DefId;
use rustc::front::map as hir_map;
use trans::common::CrateContext;

use std::ffi::CString;
use std::ptr;
use std::rc::{Rc, Weak};
use syntax::ast;
use syntax::parse::token;

pub struct NamespaceTreeNode {
    pub name: ast::Name,
    pub scope: DIScope,
    pub parent: Option<Weak<NamespaceTreeNode>>,
}

impl NamespaceTreeNode {
    pub fn mangled_name_of_contained_item(&self, item_name: &str) -> String {
        fn fill_nested(node: &NamespaceTreeNode, output: &mut String) {
            match node.parent {
                Some(ref parent) => fill_nested(&*parent.upgrade().unwrap(), output),
                None => {}
            }
            let string = node.name.as_str();
            output.push_str(&string.len().to_string());
            output.push_str(&string);
        }

        let mut name = String::from("_ZN");
        fill_nested(self, &mut name);
        name.push_str(&item_name.len().to_string());
        name.push_str(item_name);
        name.push('E');
        name
    }
}

pub fn crate_root_namespace<'a>(cx: &'a CrateContext) -> &'a str {
    &cx.link_meta().crate_name
}

pub fn namespace_for_item(cx: &CrateContext, def_id: DefId) -> Rc<NamespaceTreeNode> {
    cx.tcx().with_path(def_id, |path| {
        // prepend crate name if not already present
        let krate = if def_id.is_local() {
            let crate_namespace_name = token::intern(crate_root_namespace(cx));
            Some(hir_map::PathMod(crate_namespace_name))
        } else {
            None
        };
        let mut path = krate.into_iter().chain(path).peekable();

        let mut current_key = Vec::new();
        let mut parent_node: Option<Rc<NamespaceTreeNode>> = None;

        // Create/Lookup namespace for each element of the path.
        loop {
            // Emulate a for loop so we can use peek below.
            let path_element = match path.next() {
                Some(e) => e,
                None => break
            };
            // Ignore the name of the item (the last path element).
            if path.peek().is_none() {
                break;
            }

            let name = path_element.name();
            current_key.push(name);

            let existing_node = debug_context(cx).namespace_map.borrow()
                                                 .get(&current_key).cloned();
            let current_node = match existing_node {
                Some(existing_node) => existing_node,
                None => {
                    // create and insert
                    let parent_scope = match parent_node {
                        Some(ref node) => node.scope,
                        None => ptr::null_mut()
                    };
                    let namespace_name = name.as_str();
                    let namespace_name = CString::new(namespace_name.as_bytes()).unwrap();
                    let scope = unsafe {
                        llvm::LLVMDIBuilderCreateNameSpace(
                            DIB(cx),
                            parent_scope,
                            namespace_name.as_ptr(),
                            // cannot reconstruct file ...
                            ptr::null_mut(),
                            // ... or line information, but that's not so important.
                            0)
                    };

                    let node = Rc::new(NamespaceTreeNode {
                        name: name,
                        scope: scope,
                        parent: parent_node.map(|parent| Rc::downgrade(&parent)),
                    });

                    debug_context(cx).namespace_map.borrow_mut()
                                     .insert(current_key.clone(), node.clone());

                    node
                }
            };

            parent_node = Some(current_node);
        }

        match parent_node {
            Some(node) => node,
            None => {
                cx.sess().bug(&format!("debuginfo::namespace_for_item(): \
                                       path too short for {:?}",
                                      def_id));
            }
        }
    })
}