path: root/script-beta/core/completion.lua

local define     = require 'proto.define'
local files      = require 'files'
local guide      = require 'parser.guide'
local matchKey   = require 'core.matchkey'
local vm         = require 'vm'
local library    = require 'library'
local getLabel   = require 'core.hover.label'
local getName    = require 'core.hover.name'
local getArg     = require 'core.hover.arg'
local getDesc    = require 'core.hover.description'
local getHover   = require 'core.hover'
local config     = require 'config'
local util       = require 'utility'
local markdown   = require 'provider.markdown'
local findSource = require 'core.find-source'
local await      = require 'await'
local parser     = require 'parser'
local keyWordMap = require 'core.keyword'
local workspace  = require 'workspace'
local furi       = require 'file-uri'
local rpath      = require 'workspace.require-path'
local lang       = require 'language'

local stackID = 0
local stacks = {}
local function stack(callback)
    stackID = stackID + 1
    stacks[stackID] = callback
    return stackID
end

local function clearStack()
    stacks = {}
end

local function resolveStack(id)
    local callback = stacks[id]
    if not callback then
        return nil
    end

    -- 当进行新的 resolve 时，放弃当前的 resolve
    await.close('completion.resove')
    return await.await(callback, 'completion.resove')
end

local function trim(str)
    return str:match '^%s*(%S+)%s*$'
end

local function isSpace(char)
    if char == ' '
    or char == '\n'
    or char == '\r'
    or char == '\t' then
        return true
    end
    return false
end

local function skipSpace(text, offset)
    for i = offset, 1, -1 do
        local char = text:sub(i, i)
        if not isSpace(char) then
            return i
        end
    end
    return 0
end

local function findWord(text, offset)
    for i = offset, 1, -1 do
        if not text:sub(i, i):match '[%w_]' then
            if i == offset then
                return nil
            end
            return text:sub(i+1, offset), i+1
        end
    end
    return text:sub(1, offset), 1
end

local function findSymbol(text, offset)
    for i = offset, 1, -1 do
        local char = text:sub(i, i)
        if isSpace(char) then
            goto CONTINUE
        end
        if char == '.'
        or char == ':'
        or char == '(' then
            return char, i
        else
            return nil
        end
        ::CONTINUE::
    end
    return nil
end

local function findAnyPos(text, offset)
    for i = offset, 1, -1 do
        if not isSpace(text:sub(i, i)) then
            return i
        end
    end
    return nil
end

local function findParent(ast, text, offset)
    for i = offset, 1, -1 do
        local char = text:sub(i, i)
        if isSpace(char) then
            goto CONTINUE
        end
        local oop
        if char == '.' then
            -- `..` 的情况
            if text:sub(i-1, i-1) == '.' then
                return nil, nil
            end
            oop = false
        elseif char == ':' then
            oop = true
        else
            return nil, nil
        end
        local anyPos = findAnyPos(text, i-1)
        if not anyPos then
            return nil, nil
        end
        local parent = guide.eachSourceContain(ast.ast, anyPos, function (source)
            if source.finish == anyPos then
                return source
            end
        end)
        if parent then
            return parent, oop
        end
        ::CONTINUE::
    end
    return nil, nil
end

local function findParentInStringIndex(ast, text, offset)
    local near, nearStart
    guide.eachSourceContain(ast.ast, offset, function (source)
        local start = guide.getStartFinish(source)
        if not start then
            return
        end
        if not nearStart or nearStart < start then
            near = source
            nearStart = start
        end
    end)
    if not near or near.type ~= 'string' then
        return
    end
    local parent = near.parent
    if not parent or parent.index ~= near then
        return
    end
    -- index不可能是oop模式
    return parent.node, false
end

local function buildFunctionSnip(source, oop)
    local name = getName(source):gsub('^.-[$.:]', '')
    local defs = vm.getDefs(source, 'deep')
    local args = ''
    for _, def in ipairs(defs) do
        local defArgs = getArg(def, oop)
        if defArgs ~= '' then
            args = defArgs
            break
        end
    end
    local id = 0
    args = args:gsub('[^,]+', function (arg)
        id = id + 1
        return arg:gsub('^(%s*)(.+)', function (sp, word)
            return ('%s${%d:%s}'):format(sp, id, word)
        end)
    end)
    return ('%s(%s)'):format(name, args)
end

local function buildDetail(source)
    local types = vm.getInferType(source, 'deep')
    local literals = vm.getInferLiteral(source, 'deep')
    if literals then
        return types .. ' = ' .. literals
    else
        return types
    end
end

local function getSnip(source)
    local context = config.config.completion.displayContext
    if context <= 0 then
        return nil
    end
    local defs = vm.getRefs(source, 'deep')
    for _, def in ipairs(defs) do
        if def ~= source and def.type == 'function' then
            local uri = guide.getUri(def)
            local text = files.getText(uri)
            local lines = files.getLines(uri)
            if not text then
                return nil
            end
            local row = guide.positionOf(lines, def.start)
            local firstRow = lines[row]
            local lastRow = lines[math.min(row + context - 1, #lines)]
            local snip = text:sub(firstRow.start, lastRow.finish)
            return snip
        end
    end
end

local function buildDesc(source)
    local hover = getHover.get(source)
    local md = markdown()
    md:add('lua', hover.label)
    md:add('md',  hover.description)
    local snip = getSnip(source)
    if snip then
        md:add('md', '-------------')
        md:add('lua', snip)
    end
    return md:string()
end

local function buildFunction(results, source, oop, data)
    local snipType = config.config.completion.callSnippet
    if snipType == 'Disable' or snipType == 'Both' then
        results[#results+1] = data
    end
    if snipType == 'Both' or snipType == 'Replace' then
        local snipData = util.deepCopy(data)
        snipData.kind = define.CompletionItemKind.Snippet
        snipData.label = snipData.label .. '()'
        snipData.insertText = buildFunctionSnip(source, oop)
        snipData.insertTextFormat = 2
        snipData.id  = stack(function ()
            return {
                detail      = buildDetail(source),
                description = buildDesc(source),
            }
        end)
        results[#results+1] = snipData
    end
end

local function isSameSource(ast, source, pos)
    if source.type == 'library' then
        return false
    end
    if not files.eq(guide.getUri(source), guide.getUri(ast.ast)) then
        return false
    end
    if source.type == 'field'
    or source.type == 'method' then
        source = source.parent
    end
    return source.start <= pos and source.finish >= pos
end

local function checkLocal(ast, word, offset, results)
    local locals = guide.getVisibleLocals(ast.ast, offset)
    for name, source in pairs(locals) do
        if isSameSource(ast, source, offset) then
            goto CONTINUE
        end
        if not matchKey(word, name) then
            goto CONTINUE
        end
        if vm.hasType(source, 'function') then
            buildFunction(results, source, false, {
                label  = name,
                kind   = define.CompletionItemKind.Function,
                id     = stack(function ()
                    return {
                        detail      = buildDetail(source),
                        description = buildDesc(source),
                    }
                end),
            })
        else
            results[#results+1] = {
                label  = name,
                kind   = define.CompletionItemKind.Variable,
                id     = stack(function ()
                    return {
                        detail      = buildDetail(source),
                        description = buildDesc(source),
                    }
                end),
            }
        end
        ::CONTINUE::
    end
end

local function checkFieldFromFieldToIndex(name, parent, word, start, offset)
    if name:match '^[%a_][%w_]*$' then
        return nil
    end
    local textEdit, additionalTextEdits
    local uri = guide.getUri(parent)
    local text = files.getText(uri)
    local wordStart
    if word == '' then
        wordStart = text:match('()%S', start + 1) or (offset + 1)
    else
        wordStart = offset - #word + 1
    end
    textEdit = {
        start   = wordStart,
        finish  = offset,
        newText = ('[%q]'):format(name),
    }
    local nxt = parent.next
    if nxt then
        local dotStart
        if nxt.type == 'setfield'
        or nxt.type == 'getfield'
        or nxt.type == 'tablefield' then
            dotStart = nxt.dot.start
        elseif nxt.type == 'setmethod'
        or     nxt.type == 'getmethod' then
            dotStart = nxt.colon.start
        end
        if dotStart then
            additionalTextEdits = {
                {
                    start   = dotStart,
                    finish  = dotStart,
                    newText = '',
                }
            }
        end
    else
        if config.config.runtime.version == 'Lua 5.1'
        or config.config.runtime.version == 'LuaJIT' then
            textEdit.newText = '_G' .. textEdit.newText
        else
            textEdit.newText = '_ENV' .. textEdit.newText
        end
    end
    return textEdit, additionalTextEdits
end

local function checkFieldThen(name, src, word, start, offset, parent, oop, results)
    local value = guide.getObjectValue(src) or src
    local kind = define.CompletionItemKind.Field
    if value.type == 'function' then
        if oop then
            kind = define.CompletionItemKind.Method
        else
            kind = define.CompletionItemKind.Function
        end
        buildFunction(results, src, oop, {
            label      = name,
            kind       = kind,
            deprecated = value.deprecated,
            id         = stack(function ()
                return {
                    detail      = buildDetail(src),
                    description = buildDesc(src),
                }
            end),
        })
        return
    end
    if oop then
        return
    end
    local literal = guide.getLiteral(value)
    if literal ~= nil then
        kind = define.CompletionItemKind.Enum
    end
    local textEdit, additionalTextEdits
    if parent.next and parent.next.index then
        local str = parent.next.index
        textEdit = {
            start   = str.start + #str[2],
            finish  = offset,
            newText = name,
        }
    else
        textEdit, additionalTextEdits = checkFieldFromFieldToIndex(name, parent, word, start, offset)
    end
    results[#results+1] = {
        label      = name,
        kind       = kind,
        textEdit   = textEdit,
        additionalTextEdits = additionalTextEdits,
        id         = stack(function ()
            return {
                detail      = buildDetail(src),
                description = buildDesc(src),
            }
        end)
    }
end

local function checkFieldOfRefs(refs, ast, word, start, offset, parent, oop, results, locals)
    local fields = {}
    for _, src in ipairs(refs) do
        if src.type == 'library' then
            if src.name:sub(1, 1) == '@' then
                goto CONTINUE
            end
        end
        local key = vm.getKeyName(src)
        if not key or key:sub(1, 1) ~= 's' then
            goto CONTINUE
        end
        if isSameSource(ast, src, start) then
            goto CONTINUE
        end
        local name = key:sub(3)
        if locals and locals[name] then
            goto CONTINUE
        end
        if not matchKey(word, name) then
            goto CONTINUE
        end
        local last = fields[name]
        if not last then
            fields[name] = src
            goto CONTINUE
        end
        if src.type == 'tablefield'
        or src.type == 'setfield'
        or src.type == 'tableindex'
        or src.type == 'setindex'
        or src.type == 'setmethod' then
            fields[name] = src
            goto CONTINUE
        end
        ::CONTINUE::
    end
    for name, src in util.sortPairs(fields) do
        checkFieldThen(name, src, word, start, offset, parent, oop, results)
    end
end

local function checkField(ast, word, start, offset, parent, oop, results)
    local refs = vm.getFields(parent, 'deep')
    checkFieldOfRefs(refs, ast, word, start, offset, parent, oop, results)
end

local function checkGlobal(ast, word, start, offset, parent, oop, results)
    local locals = guide.getVisibleLocals(ast.ast, offset)
    local refs = vm.getFields(parent, 'deep')
    checkFieldOfRefs(refs, ast, word, start, offset, parent, oop, results, locals)
end

local function checkTableField(ast, word, start, results)
    local source = guide.eachSourceContain(ast.ast, start, function (source)
        if  source.start == start
        and source.parent
        and source.parent.type == 'table' then
            return source
        end
    end)
    if not source then
        return
    end
    local used = {}
    guide.eachSourceType(ast.ast, 'tablefield', function (src)
        if not src.field then
            return
        end
        local key = src.field[1]
        if  not used[key]
        and matchKey(word, key)
        and src ~= source then
            used[key] = true
            results[#results+1] = {
                label = key,
                kind  = define.CompletionItemKind.Property,
            }
        end
    end)
end

local function checkCommon(word, text, offset, results)
    local used = {}
    for _, result in ipairs(results) do
        used[result.label] = true
    end
    for _, data in ipairs(keyWordMap) do
        used[data[1]] = true
    end
    for str, pos in text:gmatch '([%a_][%w_]*)()' do
        if not used[str] and pos - 1 ~= offset then
            used[str] = true
            if matchKey(word, str) then
                results[#results+1] = {
                    label = str,
                    kind  = define.CompletionItemKind.Text,
                }
            end
        end
    end
end

local function isInString(ast, offset)
    return guide.eachSourceContain(ast.ast, offset, function (source)
        if source.type == 'string' then
            return true
        end
    end)
end

local function checkKeyWord(ast, text, start, word, hasSpace, afterLocal, results)
    local snipType = config.config.completion.keywordSnippet
    for _, data in ipairs(keyWordMap) do
        local key = data[1]
        local eq
        if hasSpace then
            eq = word == key
        else
            eq = matchKey(word, key)
        end
        if afterLocal and key ~= 'function' then
            eq = false
        end
        if eq then
            local replaced
            local extra
            if snipType == 'Both' or snipType == 'Replace' then
                local func = data[2]
                if func then
                    replaced = func(hasSpace, results)
                    extra = true
                end
            end
            if snipType == 'Both' then
                replaced = false
            end
            if not replaced then
                if not hasSpace then
                    local item = {
                        label = key,
                        kind  = define.CompletionItemKind.Keyword,
                    }
                    if extra then
                        table.insert(results, #results, item)
                    else
                        results[#results+1] = item
                    end
                end
            end
            local checkStop = data[3]
            if checkStop then
                local stop = checkStop(ast, start)
                if stop then
                    return true
                end
            end
        end
    end
end

local function checkProvideLocal(ast, word, start, results)
    local block
    guide.eachSourceContain(ast.ast, start, function (source)
        if source.type == 'function'
        or source.type == 'main' then
            block = source
        end
    end)
    if not block then
        return
    end
    local used = {}
    guide.eachSourceType(block, 'getglobal', function (source)
        if source.start > start
        and not used[source[1]]
        and matchKey(word, source[1]) then
            used[source[1]] = true
            results[#results+1] = {
                label = source[1],
                kind  = define.CompletionItemKind.Variable,
            }
        end
    end)
    guide.eachSourceType(block, 'getlocal', function (source)
        if source.start > start
        and not used[source[1]]
        and matchKey(word, source[1]) then
            used[source[1]] = true
            results[#results+1] = {
                label = source[1],
                kind  = define.CompletionItemKind.Variable,
            }
        end
    end)
end

local function checkFunctionArgByDocParam(ast, word, start, results)
    local func = guide.eachSourceContain(ast.ast, start, function (source)
        if source.type == 'function' then
            return source
        end
    end)
    if not func then
        return
    end
    local docs = func.bindDocs
    if not docs then
        return
    end
    local params = {}
    for _, doc in ipairs(docs) do
        if doc.type == 'doc.param' then
            params[#params+1] = doc
        end
    end
    local firstArg = func.args and func.args[1]
    if not firstArg
    or firstArg.start <= start and firstArg.finish >= start then
        local firstParam = params[1]
        if firstParam and matchKey(word, firstParam.param[1]) then
            local label = {}
            for _, param in ipairs(params) do
                label[#label+1] = param.param[1]
            end
            results[#results+1] = {
                label = table.concat(label, ', '),
                kind  = define.CompletionItemKind.Snippet,
            }
        end
    end
    for _, doc in ipairs(params) do
        if matchKey(word, doc.param[1]) then
            results[#results+1] = {
                label = doc.param[1],
                kind  = define.CompletionItemKind.Interface,
            }
        end
    end
end

local function isAfterLocal(text, start)
    local pos = skipSpace(text, start-1)
    local word = findWord(text, pos)
    return word == 'local'
end

local function checkUri(ast, text, offset, results)
    local collect = {}
    local myUri = guide.getUri(ast.ast)
    guide.eachSourceContain(ast.ast, offset, function (source)
        if source.type ~= 'string' then
            return
        end
        local callargs = source.parent
        if not callargs or callargs.type ~= 'callargs' then
            return
        end
        if callargs[1] ~= source then
            return
        end
        local call = callargs.parent
        local func = call.node
        local literal = guide.getLiteral(source)
        local lib = vm.getLibrary(func)
        if not lib then
            return
        end
        if     lib.name == 'require' then
            for uri in files.eachFile() do
                uri = files.getOriginUri(uri)
                if files.eq(myUri, uri) then
                    goto CONTINUE
                end
                local path = workspace.getRelativePath(uri)
                local infos = rpath.getVisiblePath(path, config.config.runtime.path)
                for _, info in ipairs(infos) do
                    if matchKey(literal, info.expect) then
                        if not collect[info.expect] then
                            collect[info.expect] = {
                                textEdit = {
                                    start  = source.start + #source[2],
                                    finish = source.finish - #source[2],
                                }
                            }
                        end
                        collect[info.expect][#collect[info.expect]+1] = ([=[* [%s](%s) %s]=]):format(
                            path,
                            uri,
                            lang.script('HOVER_USE_LUA_PATH', info.searcher)
                        )
                    end
                end
                ::CONTINUE::
            end
        elseif lib.name == 'dofile'
        or     lib.name == 'loadfile' then
            for uri in files.eachFile() do
                uri = files.getOriginUri(uri)
                if files.eq(myUri, uri) then
                    goto CONTINUE
                end
                local path = workspace.getRelativePath(uri)
                if matchKey(literal, path) then
                    if not collect[path] then
                        collect[path] = {
                            textEdit = {
                                start  = source.start + #source[2],
                                finish = source.finish - #source[2],
                            }
                        }
                    end
                    collect[path][#collect[path]+1] = ([=[[%s](%s)]=]):format(
                        path,
                        uri
                    )
                end
                ::CONTINUE::
            end
        end
    end)
    for label, infos in util.sortPairs(collect) do
        local mark = {}
        local des  = {}
        for _, info in ipairs(infos) do
            if not mark[info] then
                mark[info] = true
                des[#des+1] = info
            end
        end
        results[#results+1] = {
            label = label,
            kind  = define.CompletionItemKind.Reference,
            description = table.concat(des, '\n'),
            textEdit = infos.textEdit,
        }
    end
end

local function checkLenPlusOne(ast, text, offset, results)
    guide.eachSourceContain(ast.ast, offset, function (source)
        if source.type == 'getindex'
        or source.type == 'setindex' then
            local _, pos = text:find('%s*%[%s*%#', source.node.finish)
            if not pos then
                return
            end
            local nodeText = text:sub(source.node.start, source.node.finish)
            local writingText = trim(text:sub(pos + 1, offset - 1)) or ''
            if not matchKey(writingText, nodeText) then
                return
            end
            if source.parent == guide.getParentBlock(source) then
                -- state
                local label = text:match('%#[ \t]*', pos) .. nodeText .. '+1'
                local eq = text:find('^%s*%]?%s*%=', source.finish)
                local newText = label .. ']'
                if not eq then
                    newText = newText .. ' = '
                end
                results[#results+1] = {
                    label    = label,
                    kind     = define.CompletionItemKind.Snippet,
                    textEdit = {
                        start   = pos,
                        finish  = source.finish,
                        newText = newText,
                    },
                }
            else
                -- exp
                local label = text:match('%#[ \t]*', pos) .. nodeText
                local newText = label .. ']'
                results[#results+1] = {
                    label    = label,
                    kind     = define.CompletionItemKind.Snippet,
                    textEdit = {
                        start   = pos,
                        finish  = source.finish,
                        newText = newText,
                    },
                }
            end
        end
    end)
end

local function isFuncArg(ast, offset)
    return guide.eachSourceContain(ast.ast, offset, function (source)
        if source.type == 'funcargs' then
            return true
        end
    end)
end

local function trySpecial(ast, text, offset, results)
    if isInString(ast, offset) then
        checkUri(ast, text, offset, results)
        return
    end
    -- x[#x+1]
    checkLenPlusOne(ast, text, offset, results)
end

local function tryIndex(ast, text, offset, results)
    local parent, oop = findParentInStringIndex(ast, text, offset)
    if not parent then
        return
    end
    local word = parent.next.index[1]
    checkField(ast, word, offset, offset, parent, oop, results)
end

local function tryWord(ast, text, offset, results)
    local finish = skipSpace(text, offset)
    local word, start = findWord(text, finish)
    if not word then
        return nil
    end
    local hasSpace = finish ~= offset
    if isInString(ast, offset) then
    else
        local parent, oop = findParent(ast, text, start - 1)
        if parent then
            if not hasSpace then
                checkField(ast, word, start, offset, parent, oop, results)
            end
        elseif isFuncArg(ast, offset) then
            checkProvideLocal(ast, word, start, results)
            checkFunctionArgByDocParam(ast, word, start, results)
        else
            local afterLocal = isAfterLocal(text, start)
            local stop = checkKeyWord(ast, text, start, word, hasSpace, afterLocal, results)
            if stop then
                return
            end
            if not hasSpace then
                if afterLocal then
                    checkProvideLocal(ast, word, start, results)
                else
                    checkLocal(ast, word, start, results)
                    checkTableField(ast, word, start, results)
                    local env = guide.getENV(ast.ast, start)
                    checkGlobal(ast, word, start, offset, env, false, results)
                end
            end
        end
        if not hasSpace then
            checkCommon(word, text, offset, results)
        end
    end
end

local function trySymbol(ast, text, offset, results)
    local symbol, start = findSymbol(text, offset)
    if not symbol then
        return nil
    end
    if isInString(ast, offset) then
        return nil
    end
    if symbol == '.'
    or symbol == ':' then
        local parent, oop = findParent(ast, text, start)
        if parent then
            checkField(ast, '', start, offset, parent, oop, results)
        end
    end
    if symbol == '(' then
        checkFunctionArgByDocParam(ast, '', start, results)
    end
end

local function getCallEnums(source, index)
    if source.type == 'library' and source.value.type == 'function' then
        local func = source.value
        if not func then
            return nil
        end
        if not func.args then
            return nil
        end
        if not func.enums then
            return nil
        end
        local arg = func.args[index]
        if not arg then
            return nil
        end
        local argName = arg.name
        if not argName then
            return nil
        end
        local enums = {}
        for _, enum in ipairs(func.enums) do
            if enum.name == argName then
                enums[#enums+1] = {
                    label       = enum.enum,
                    description = enum.description,
                    kind        = define.CompletionItemKind.EnumMember,
                }
            end
        end
        return enums
    end
    if source.type == 'function' and source.bindDocs then
        local arg = source.args and source.args[index]
        if not arg then
            return
        end
        for _, doc in ipairs(source.bindDocs) do
            if  doc.type == 'doc.param'
            and doc.param[1] == arg[1] then
                local enums = {}
                for _, enum in ipairs(vm.getDocEnums(doc.extends)) do
                    enums[#enums+1] = {
                        label       = enum[1],
                        description = enum.comment,
                        kind        = define.CompletionItemKind.EnumMember,
                    }
                end
                return enums
            end
        end
    end
end

local function tryLabelInString(label, arg)
    if not arg or arg.type ~= 'string' then
        return label
    end
    local str = parser:grammar(label, 'String')
    if not str then
        return label
    end
    if not matchKey(arg[1], str[1]) then
        return nil
    end
    return util.viewString(str[1], arg[2])
end

local function mergeEnums(a, b, text, arg)
    local mark = {}
    for _, enum in ipairs(a) do
        mark[enum.label] = true
    end
    for _, enum in ipairs(b) do
        local label = tryLabelInString(enum.label, arg)
        if label and not mark[label] then
            mark[label] = true
            local result = {
                label       = label,
                kind        = define.CompletionItemKind.EnumMember,
                description = enum.description,
                textEdit    = arg and {
                    start   = arg.start,
                    finish  = arg.finish,
                    newText = label,
                },
            }
            a[#a+1] = result
        end
    end
end

local function findCall(ast, text, offset)
    local call
    guide.eachSourceContain(ast.ast, offset, function (src)
        if src.type == 'call' then
            if not call or call.start < src.start then
                call = src
            end
        end
    end)
    return call
end

local function getCallArgInfo(call, text, offset)
    if not call.args then
        return 1, nil
    end
    for index, arg in ipairs(call.args) do
        if arg.start <= offset and arg.finish >= offset then
            return index, arg
        end
    end
    return #call.args + 1, nil
end

local function tryCallArg(ast, text, offset, results)
    local call = findCall(ast, text, offset)
    if not call then
        return
    end
    local myResults = {}
    local argIndex, arg = getCallArgInfo(call, text, offset)
    if arg and arg.type == 'function' then
        return
    end
    local defs = vm.getDefs(call.node, 'deep')
    for _, def in ipairs(defs) do
        local enums = getCallEnums(def, argIndex)
        if enums then
            mergeEnums(myResults, enums, text, arg)
        end
    end
    for _, enum in ipairs(myResults) do
        results[#results+1] = enum
    end
end

local function getComment(ast, offset)
    for _, comm in ipairs(ast.comms) do
        if offset >= comm.start and offset <= comm.finish then
            return comm
        end
    end
    return nil
end

local function tryLuaDocCate(line, results)
    local word = line:sub(3)
    for _, docType in ipairs {'class', 'type', 'alias', 'param', 'return', 'field', 'generic', 'vararg', 'overload'} do
        if matchKey(word, docType) then
            results[#results+1] = {
                label       = docType,
                kind        = define.CompletionItemKind.Event,
            }
        end
    end
end

local function getLuaDocByContain(ast, offset)
    local result
    local range = math.huge
    guide.eachSourceContain(ast.ast.docs, offset, function (src)
        if not src.start then
            return
        end
        if  range  >= offset - src.start
        and offset <= src.finish then
            range = offset - src.start
            result = src
        end
    end)
    return result
end

local function getLuaDocByErr(ast, text, start, offset)
    local targetError
    for _, err in ipairs(ast.errs) do
        if  err.finish <= offset
        and err.start >= start  then
            if not text:sub(err.finish + 1, offset):find '%S' then
                targetError = err
                break
            end
        end
    end
    if not targetError then
        return nil
    end
    local targetDoc
    for i = #ast.ast.docs, 1, -1 do
        local doc = ast.ast.docs[i]
        if doc.finish <= targetError.start then
            targetDoc = doc
            break
        end
    end
    return targetError, targetDoc
end

local function tryLuaDocBySource(ast, offset, source, results)
    if source.type == 'doc.extends.name' then
        if source.parent.type == 'doc.class' then
            for _, doc in ipairs(vm.getDocTypes '*') do
                if  doc.type == 'doc.class.name'
                and doc.parent ~= source.parent
                and matchKey(source[1], doc[1]) then
                    results[#results+1] = {
                        label       = doc[1],
                        kind        = define.CompletionItemKind.Class,
                    }
                end
            end
        end
    elseif source.type == 'doc.type.name' then
        for _, doc in ipairs(vm.getDocTypes '*') do
            if  (doc.type == 'doc.class.name' or doc.type == 'doc.alias.name')
            and doc.parent ~= source.parent
            and matchKey(source[1], doc[1]) then
                results[#results+1] = {
                    label       = doc[1],
                    kind        = define.CompletionItemKind.Class,
                }
            end
        end
    elseif source.type == 'doc.param.name' then
        local func = guide.eachSourceBetween(ast.ast, offset, math.huge, function (src)
            if src.type == 'function' and src.start > offset then
                return src
            end
        end)
        if not func or not func.args then
            return
        end
        for i, arg in ipairs(func.args) do
            if matchKey(source[1], arg[1]) then
                results[#results+1] = {
                    label  = arg[1],
                    kind   = define.CompletionItemKind.Interface,
                }
            end
        end
    end
end

local function tryLuaDocByErr(ast, offset, err, docState, results)
    if err.type == 'LUADOC_MISS_CLASS_EXTENDS_NAME' then
        for _, doc in ipairs(vm.getDocTypes '*') do
            if  doc.type == 'doc.class.name'
            and doc.parent ~= docState then
                results[#results+1] = {
                    label       = doc[1],
                    kind        = define.CompletionItemKind.Class,
                }
            end
        end
    elseif err.type == 'LUADOC_MISS_TYPE_NAME' then
        for _, doc in ipairs(vm.getDocTypes '*') do
            if  (doc.type == 'doc.class.name' or doc.type == 'doc.alias.name') then
                results[#results+1] = {
                    label       = doc[1],
                    kind        = define.CompletionItemKind.Class,
                }
            end
        end
    elseif err.type == 'LUADOC_MISS_PARAM_NAME' then
        local func = guide.eachSourceBetween(ast.ast, offset, math.huge, function (src)
            if src.type == 'function' and src.start > offset then
                return src
            end
        end)
        if not func or not func.args then
            return
        end
        local label = {}
        local insertText = {}
        for i, arg in ipairs(func.args) do
            if arg[1] then
                label[#label+1] = arg[1]
                if i == 1 then
                    insertText[i] = ('%s any'):format(arg[1])
                else
                    insertText[i] = ('---@param %s any'):format(arg[1])
                end
            end
        end
        results[#results+1] = {
            label      = table.concat(label, ', '),
            kind       = define.CompletionItemKind.Snippet,
            insertText = table.concat(insertText, '\n'),
        }
        for i, arg in ipairs(func.args) do
            if arg[1] then
                results[#results+1] = {
                    label  = arg[1],
                    kind   = define.CompletionItemKind.Interface,
                }
            end
        end
    end
end

local function tryLuaDocFeatures(line, ast, comm, offset, results)
end

local function tryLuaDoc(ast, text, offset, results)
    local comm = getComment(ast, offset)
    local line = text:sub(comm.start, offset)
    if not line then
        return
    end
    if line:sub(1, 2) ~= '-@' then
        return
    end
    -- 尝试 ---@$
    local cate = line:match('%a*', 3)
    if #cate + 2 >= #line then
        tryLuaDocCate(line, results)
        return
    end
    -- 尝试一些其他特征
    if tryLuaDocFeatures(line, ast, comm, offset, results) then
        return
    end
    -- 根据输入中的source来补全
    local source = getLuaDocByContain(ast, offset)
    if source then
        tryLuaDocBySource(ast, offset, source, results)
        return
    end
    -- 根据附近的错误消息来补全
    local err, doc = getLuaDocByErr(ast, text, comm.start, offset)
    if err then
        tryLuaDocByErr(ast, offset, err, doc, results)
        return
    end
end

local function completion(uri, offset)
    local ast = files.getAst(uri)
    local text = files.getText(uri)
    local results = {}
    clearStack()
    if ast then
        if getComment(ast, offset) then
            tryLuaDoc(ast, text, offset, results)
        else
            trySpecial(ast, text, offset, results)
            tryWord(ast, text, offset, results)
            tryIndex(ast, text, offset, results)
            trySymbol(ast, text, offset, results)
            tryCallArg(ast, text, offset, results)
        end
    else
        local word = findWord(text, offset)
        if word then
            checkCommon(word, text, offset, results)
        end
    end

    if #results == 0 then
        return nil
    end
    return results
end

local function resolve(id)
    return resolveStack(id)
end

return {
    completion = completion,
    resolve    = resolve,
}