local error      = error
local type       = type
local next       = next
local tostring   = tostring

_ENV = nil

local m = {}

local blockTypes = {
    ['while']       = true,
    ['in']          = true,
    ['loop']        = true,
    ['repeat']      = true,
    ['do']          = true,
    ['function']    = true,
    ['ifblock']     = true,
    ['elseblock']   = true,
    ['elseifblock'] = true,
    ['main']        = true,
}

local breakBlockTypes = {
    ['while']       = true,
    ['in']          = true,
    ['loop']        = true,
    ['repeat']      = true,
}

m.childMap = {
    ['main']        = {'#'},
    ['repeat']      = {'#', 'filter'},
    ['while']       = {'filter', '#'},
    ['in']          = {'keys', '#'},
    ['loop']        = {'loc', 'max', 'step', '#'},
    ['if']          = {'#'},
    ['ifblock']     = {'filter', '#'},
    ['elseifblock'] = {'filter', '#'},
    ['elseblock']   = {'#'},
    ['setfield']    = {'node', 'field', 'value'},
    ['setglobal']   = {'value'},
    ['local']       = {'attrs', 'value'},
    ['setlocal']    = {'value'},
    ['return']      = {'#'},
    ['do']          = {'#'},
    ['select']      = {'vararg'},
    ['index']       = {'index'},
    ['table']       = {'#'},
    ['tableindex']  = {'index', 'value'},
    ['tablefield']  = {'value'},
    ['function']    = {'args', '#'},
    ['funcargs']    = {'#'},
    ['setmethod']   = {'node', 'method', 'value'},
    ['getmethod']   = {'node', 'method'},
    ['setindex']    = {'node', 'index', 'value'},
    ['getindex']    = {'node', 'index'},
    ['paren']       = {'exp'},
    ['call']        = {'node', 'args'},
    ['callargs']    = {'#'},
    ['getfield']    = {'node', 'field'},
    ['list']        = {'#'},
    ['binary']      = {1, 2},
    ['unary']       = {1}
}

m.actionMap = {
    ['main']        = {'#'},
    ['repeat']      = {'#'},
    ['while']       = {'#'},
    ['in']          = {'#'},
    ['loop']        = {'#'},
    ['if']          = {'#'},
    ['ifblock']     = {'#'},
    ['elseifblock'] = {'#'},
    ['elseblock']   = {'#'},
    ['do']          = {'#'},
    ['function']    = {'#'},
    ['funcargs']    = {'#'},
}

--- 是否是字面量
function m.isLiteral(obj)
    local tp = obj.type
    return tp == 'nil'
        or tp == 'boolean'
        or tp == 'string'
        or tp == 'number'
        or tp == 'table'
end

--- 获取字面量
function m.getLiteral(obj)
    local tp = obj.type
    if     tp == 'boolean' then
        return obj[1]
    elseif tp == 'string' then
        return obj[1]
    elseif tp == 'number' then
        return obj[1]
    end
    return nil
end

--- 寻找所在函数
function m.getParentFunction(obj)
    for _ = 1, 1000 do
        obj = obj.parent
        if not obj then
            break
        end
        local tp = obj.type
        if tp == 'function' or tp == 'main' then
            return obj
        end
    end
    return nil
end

--- 寻找所在区块
function m.getBlock(obj)
    for _ = 1, 1000 do
        if not obj then
            return nil
        end
        local tp = obj.type
        if blockTypes[tp] then
            return obj
        end
        obj = obj.parent
    end
    error('guide.getBlock overstack')
end

--- 寻找所在父区块
function m.getParentBlock(obj)
    for _ = 1, 1000 do
        obj = obj.parent
        if not obj then
            return nil
        end
        local tp = obj.type
        if blockTypes[tp] then
            return obj
        end
    end
    error('guide.getParentBlock overstack')
end

--- 寻找所在可break的父区块
function m.getBreakBlock(obj)
    for _ = 1, 1000 do
        obj = obj.parent
        if not obj then
            return nil
        end
        local tp = obj.type
        if breakBlockTypes[tp] then
            return obj
        end
        if tp == 'function' then
            return nil
        end
    end
    error('guide.getBreakBlock overstack')
end

--- 寻找根区块
function m.getRoot(obj)
    for _ = 1, 1000 do
        local parent = obj.parent
        if not parent then
            return obj
        end
        obj = parent
    end
    error('guide.getRoot overstack')
end

--- 寻找函数的不定参数，返回不定参在第几个参数上，以及该参数对象。
--- 如果函数是主函数，则返回`0, nil`。
---@return table
---@return integer
function m.getFunctionVarArgs(func)
    if func.type == 'main' then
        return 0, nil
    end
    if func.type ~= 'function' then
        return nil, nil
    end
    local args = func.args
    if not args then
        return nil, nil
    end
    for i = 1, #args do
        local arg = args[i]
        if arg.type == '...' then
            return i, arg
        end
    end
    return nil, nil
end

--- 获取指定区块中可见的局部变量
---@param block table
---@param name string {comment = '变量名'}
---@param pos integer {comment = '可见位置'}
function m.getLocal(block, name, pos)
    block = m.getBlock(block)
    for _ = 1, 1000 do
        if not block then
            return nil
        end
        local locals = block.locals
        local res
        if not locals then
            goto CONTINUE
        end
        for i = 1, #locals do
            local loc = locals[i]
            if loc.effect > pos then
                break
            end
            if loc[1] == name then
                if not res or res.effect < loc.effect then
                    res = loc
                end
            end
        end
        if res then
            return res, res
        end
        ::CONTINUE::
        block = m.getParentBlock(block)
    end
    error('guide.getLocal overstack')
end

--- 获取指定区块中可见的标签
---@param block table
---@param name string {comment = '标签名'}
function m.getLabel(block, name)
    block = m.getBlock(block)
    for _ = 1, 1000 do
        if not block then
            return nil
        end
        local labels = block.labels
        if labels then
            local label = labels[name]
            if label then
                return label
            end
        end
        if block.type == 'function' then
            return nil
        end
        block = m.getParentBlock(block)
    end
    error('guide.getLocal overstack')
end

--- 判断source是否包含offset
function m.isContain(source, offset)
    return source.start <= offset and source.finish >= offset - 1
end

--- 判断offset在source的影响范围内
---
--- 主要针对赋值等语句时，key包含value
function m.isInRange(source, offset)
    return source.start <= offset and (source.range or source.finish) >= offset - 1
end

--- 添加child
function m.addChilds(list, obj, map)
    local keys = map[obj.type]
    if keys then
        for i = 1, #keys do
            local key = keys[i]
            if key == '#' then
                for i = 1, #obj do
                    list[#list+1] = obj[i]
                end
            else
                list[#list+1] = obj[key]
            end
        end
    end
end

--- 遍历所有包含offset的source
function m.eachSourceContain(ast, offset, callback)
    local list = { ast }
    while true do
        local len = #list
        if len == 0 then
            return
        end
        local obj = list[len]
        list[len] = nil
        if m.isInRange(obj, offset) then
            if m.isContain(obj, offset) then
                callback(obj)
            end
            m.addChilds(list, obj, m.childMap)
        end
    end
end

--- 遍历所有指定类型的source
function m.eachSourceType(ast, type, callback)
    local cache = ast.typeCache
    if not cache then
        local mark = {}
        cache = {}
        ast.typeCache = cache
        m.eachSource(ast, function (source)
            if mark[source] then
                return
            end
            mark[source] = true
            local tp = source.type
            local myCache = cache[tp]
            if not myCache then
                myCache = {}
                cache[tp] = myCache
            end
            myCache[#myCache+1] = source
        end)
    end
    local myCache = cache[type]
    if not myCache then
        return
    end
    for i = 1, #myCache do
        callback(myCache[i])
    end
end

--- 遍历所有的source
function m.eachSource(ast, callback)
    local list = { ast }
    while true do
        local len = #list
        if len == 0 then
            return
        end
        local obj = list[len]
        list[len] = nil
        callback(obj)
        m.addChilds(list, obj, m.childMap)
    end
end

--- 获取偏移对应的坐标（row从0开始，col为光标位置）
---@param lines table
---@return integer {name = 'row'}
---@return integer {name = 'col'}
function m.positionOf(lines, offset)
    if offset < 1 then
        return 0, 0
    end
    local lastLine = lines[#lines]
    if offset > lastLine.finish then
        return #lines - 1, lastLine.finish - lastLine.start
    end
    local min = 1
    local max = #lines
    for _ = 1, 100 do
        if max <= min then
            local line = lines[min]
            return min - 1, offset - line.start
        end
        local row = (max - min) // 2 + min
        local line = lines[row]
        if offset < line.start then
            max = row - 1
        elseif offset >= line.finish then
            min = row + 1
        else
            return row - 1, offset - line.start
        end
    end
    error('Stack overflow!')
end

--- 获取坐标对应的偏移（row从0开始，col为光标位置）
---@param lines table
---@param row integer
---@param col integer
---@return integer {name = 'offset'}
function m.offsetOf(lines, row, col)
    if row < 0 then
        return 0
    end
    if row > #lines - 1 then
        local lastLine = lines[#lines]
        return lastLine.finish
    end
    local line = lines[row + 1]
    local len = line.finish - line.start
    if col < 0 then
        return line.start
    elseif col > len then
        return line.finish
    else
        return line.start + col
    end
end

function m.lineContent(lines, text, row)
    local line = lines[row + 1]
    if not line then
        return ''
    end
    return text:sub(line.start + 1, line.finish)
end

function m.lineRange(lines, row)
    local line = lines[row + 1]
    if not line then
        return 0, 0
    end
    return line.start + 1, line.finish
end

function m.getKeyName(obj)
    local tp = obj.type
    if tp == 'getglobal'
    or tp == 'setglobal' then
        return 's|' .. obj[1]
    elseif tp == 'getfield'
    or     tp == 'setfield'
    or     tp == 'tablefield' then
        return 's|' .. obj.field[1]
    elseif tp == 'getmethod'
    or     tp == 'setmethod' then
        return 's|' .. obj.method[1]
    elseif tp == 'getindex'
    or     tp == 'setindex'
    or     tp == 'tableindex' then
        return m.getKeyName(obj.index)
    elseif tp == 'field'
    or     tp == 'method' then
        return 's|' .. obj[1]
    elseif tp == 'index' then
        return m.getKeyName(obj.index)
    elseif tp == 'string' then
        local s = obj[1]
        if s then
            return 's|' .. s
        else
            return s
        end
    elseif tp == 'number' then
        local n = obj[1]
        if n then
            return ('n|%q'):format(obj[1])
        else
            return 'n'
        end
    elseif tp == 'boolean' then
        local b = obj[1]
        if b then
            return 'b|' .. tostring(b)
        else
            return 'b'
        end
    end
    return nil
end

function m.getENV(ast)
    if ast.type ~= 'main' then
        return nil
    end
    return ast.locals[1]
end

--- 测试 a 到 b 的路径（不经过函数，不考虑 goto），
--- 每个路径是一个 block 。
---
--- 如果 a 在 b 的前面，返回 `"before"` 加上 2个`list<block>`
---
--- 如果 a 在 b 的后面，返回 `"after"` 加上 2个`list<block>`
---
--- 否则返回 `false`
---
--- 返回的2个 `list` 分别为基准block到达 a 与 b 的路径。
---@param a table
---@param b table
---@return string|boolean mode
---@return table|nil pathA
---@return table|nil pathB
function m.getPath(a, b)
    --- 首先测试双方在同一个函数内
    if m.getParentFunction(a) ~= m.getParentFunction(b) then
        return false
    end
    local mode
    local objA
    local objB
    if a.start < b.start then
        mode = 'before'
        objA = a
        objB = b
    else
        mode = 'after'
        objA = b
        objB = a
    end
    local pathA = {}
    local pathB = {}
    for _ = 1, 1000 do
        objA = m.getParentBlock(objA)
        pathA[#pathA+1] = objA
        if objA.type == 'function' or objA.type == 'main' then
            break
        end
    end
    for _ = 1, 1000 do
        objB = m.getParentBlock(objB)
        pathB[#pathB+1] = objB
        if objB.type == 'function' or objB.type == 'main' then
            break
        end
    end
    -- pathA: {1, 2, 3, 4, 5}
    -- pathB: {5, 6, 2, 3}
    local top = #pathB
    local start
    for i = #pathA, 1, -1 do
        local currentBlock = pathA[i]
        if currentBlock == pathB[top] then
            start = i
            break
        end
    end
    -- pathA: {   1, 2, 3}
    -- pathB: {5, 6, 2, 3}
    local extra = 0
    local align = top - start
    for i = start, 1, -1 do
        local currentA = pathA[i]
        local currentB = pathB[i+align]
        if currentA ~= currentB then
            extra = i
            break
        end
    end
    -- pathA: {1}
    local resultA = {}
    for i = extra, 1, -1 do
        resultA[#resultA+1] = pathA[i]
    end
    -- pathB: {5, 6}
    local resultB = {}
    for i = extra + align, 1, -1 do
        resultB[#resultB+1] = pathB[i]
    end
    return mode, resultA, resultB
end

return m