--------------------------------------------------------------------------------
--  Copyright (c) 2012 Sierra Wireless.
--  All rights reserved. This program and the accompanying materials
--  are made available under the terms of the Eclipse Public License v1.0
--  which accompanies this distribution, and is available at
--  http://www.eclipse.org/legal/epl-v10.html
--
--  Contributors:
--       Kevin KIN-FOO <kkinfoo@sierrawireless.com>
--           - initial API and implementation and initial documentation
--------------------------------------------------------------------------------
local M = {}
require 'metalua.loader'
local compiler = require 'metalua.compiler'
local mlc = compiler.new()
local Q = require 'metalua.treequery'

-- Enable to retrieve all Javadoc-like comments from C code
function M.c(code)
  if not code then return nil, 'No code provided' end
  local comments = {}
  -- Loop over comments stripping cosmetic '*'
  for comment in code:gmatch('%s*/%*%*+(.-)%*+/') do
    -- All Lua special comment are prefixed with an '-',
    -- so we also comment C comment to make them compliant
    table.insert(comments, '-'..comment)
  end
  return comments
end

-- Enable to retrieve "---" comments from Lua code
function M.lua( code )
  if not code then return nil, 'No code provided' end

  -- manage shebang
  if code then code = code:gsub("^(#.-\n)", function (s) return string.rep(' ',string.len(s)) end) end

  -- check for errors
  local f, err = loadstring(code,'source_to_check')
  if not f then
    return nil, 'Syntax error.\n' .. err
  end

  -- Get ast from file
  local status, ast = pcall(mlc.src_to_ast, mlc, code)
  --
  -- Detect parsing errors
  --
  if not status then
    return nil, 'There might be a syntax error.\n' .. ast
  end

  --
  -- Extract commented nodes from AST
  --

  -- Function enabling commented node selection
  local function acceptcommentednode(node)
    return node.lineinfo and ( node.lineinfo.last.comments or node.lineinfo.first.comments )
  end

  -- Fetch commented node from AST
  local commentednodes = Q(ast):filter( acceptcommentednode ):list()

  -- Comment cache to avoid selecting same comment twice
  local commentcache = {}
  -- Will contain selected comments
  local comments = {}

  -- Loop over commented nodes
  for _, node in ipairs( commentednodes ) do

    -- A node can is relateds to comment before and after itself,
    -- the following gathers them.
    local commentlists = {}
    if node.lineinfo and node.lineinfo.first.comments then
      table.insert(commentlists,  node.lineinfo.first.comments)
    end
    if node.lineinfo and node.lineinfo.last.comments then
      table.insert(commentlists,  node.lineinfo.last.comments)
    end
    -- Now that we have comments before and fater the node,
    -- collect them in a single table
    for _, list in ipairs( commentlists ) do
      for _, commenttable in ipairs(list) do
        -- Only select special comments
        local firstcomment = #commenttable > 0 and #commenttable[1] > 0 and commenttable[1]
        if firstcomment:sub(1, 1) == '-' then
          for _, comment in ipairs( commenttable ) do
            -- Only comments which were not already collected
            if not commentcache[comment] then
              commentcache[comment] = true
              table.insert(comments, comment)
            end
          end
        end
      end
    end
  end
  return comments
end
return M