local guide     = require 'parser.guide'
local workspace = require 'workspace'
local files     = require 'files'
local searcher  = require 'searcher'

local function findDef(source, callback)
    if  source.type ~= 'local'
    and source.type ~= 'getlocal'
    and source.type ~= 'setlocal'
    and source.type ~= 'setglobal'
    and source.type ~= 'getglobal'
    and source.type ~= 'field'
    and source.type ~= 'method'
    and source.type ~= 'string'
    and source.type ~= 'number'
    and source.type ~= 'boolean'
    and source.type ~= 'goto' then
        return
    end
    searcher.eachRef(source, function (info)
        if info.mode == 'declare'
        or info.mode == 'set' 
        or info.mode == 'return' then
            local src  = info.source
            local root = guide.getRoot(src)
            local uri  = root.uri
            if     src.type == 'setfield'
            or     src.type == 'getfield'
            or     src.type == 'tablefield' then
                callback(src.field, uri)
            elseif src.type == 'setindex'
            or     src.type == 'getindex'
            or     src.type == 'tableindex' then
                callback(src.index, uri)
            elseif src.type == 'getmethod'
            or     src.type == 'setmethod' then
                callback(src.method, uri)
            else
                callback(src, uri)
            end
        end
    end)
end

local function checkRequire(source, offset, callback)
    if source.type ~= 'call' then
        return
    end
    local func = source.node
    local pathSource = source.args and source.args[1]
    if not pathSource then
        return
    end
    if not guide.isContain(pathSource, offset) then
        return
    end
    local literal = guide.getLiteral(pathSource)
    if type(literal) ~= 'string' then
        return
    end
    local name = searcher.getSpecialName(func)
    if     name == 'require' then
        local result = workspace.findUrisByRequirePath(literal, true)
        for _, uri in ipairs(result) do
            callback(uri)
        end
    elseif name == 'dofile'
    or     name == 'loadfile' then
        local result = workspace.findUrisByFilePath(literal, true)
        for _, uri in ipairs(result) do
            callback(uri)
        end
    end
end

return function (uri, offset)
    local ast = files.getAst(uri)
    if not ast then
        return nil
    end
    local results = {}
    guide.eachSourceContain(ast.ast, offset, function (source)
        checkRequire(source, offset, function (uri)
            results[#results+1] = {
                uri    = files.getOriginUri(uri),
                source = source,
                target = {
                    start  = 0,
                    finish = 0,
                }
            }
        end)
        findDef(source, function (target, uri)
            results[#results+1] = {
                target = target,
                uri    = files.getOriginUri(uri),
                source = source,
            }
        end)
    end)
    if #results == 0 then
        return nil
    end
    return results
end