-----------------------------------------------------------------------------
-- Imports and dependencies
-----------------------------------------------------------------------------
local math = require("math")
local string = require("string")
local table = require("table")

-----------------------------------------------------------------------------
-- Module declaration
-----------------------------------------------------------------------------
local json = {} -- Public namespace
local json_private = {} -- Private namespace

-- Public constants
json.EMPTY_ARRAY = {}
json.EMPTY_OBJECT = {}
json_private.attributeMap = {}

-- Public functions

-- Private functions
local decode_scanArray
local decode_scanComment
local decode_scanConstant
local decode_scanNumber
local decode_scanObject
local setObjectType
local decode_scanString
local decode_scanWhitespace
local isArray
local isEncodable
local avoidLoopOver
local index
local getTableType
local checkAttributeInfo
local setClassType
local bsonIgnore = "MongoDB.Bson.Serialization.Attributes.BsonIgnoreAttribute"
local bsonRequired = "MongoDB.Bson.Serialization.Attributes.BsonRequiredAttribute"

-----------------------------------------------------------------------------
-- PUBLIC FUNCTIONS
-----------------------------------------------------------------------------
--- Encodes an arbitrary Lua object / variable.
-- @param v The Lua object / variable to be JSON encoded.
-- @return String containing the JSON encoding in internal Lua string format (i.e. not unicode)
function json.encode(v)
    avoidLoopOver()
    -- Handle nil values
    if v == nil then
        return "null"
    end

    local vtype = type(v)

    -- Handle strings
    if vtype == "string" then
        return '"' .. json_private.encodeString(v) .. '"' -- Need to handle encoding in string
    end

    -- Handle booleans
    if vtype == "number" or vtype == "boolean" then
        return tostring(v)
    end

    -- Handle tables
    if vtype == "table" then
        local rval = {}
        if not getmetatable(v) then
            return "{}"
        end
        table.insert(rval,'"_t":"'.. getmetatable(v).__name__ .. '"')
        -- Consider arrays separately
        local tType = getTableType(v)
        if (tType == "array") then
            for i = 1, #v do
                table.insert(rval, json.encode(v[i]))
            end
        elseif tType == "hashset" then
            for i, _ in pairs(v) do
                table.insert(rval, json.encode(i))
            end
        elseif tType == "dictionary" then
            for i, j in pairs(v) do
                if isEncodable(i) and isEncodable(j) then
                    table.insert(rval, '"' .. json_private.encodeString(i) .. '":' .. json.encode(j))
                end
            end
        else
            local map = {}
            local needMap = {}
            checkAttributeInfo(v, map, needMap)
            map = table.unique(map, true)
            needMap = table.unique(needMap, true)
            for i, j in pairs(v) do
                if isEncodable(i) and isEncodable(j) and not IsVlaueInTable(map, i) then
                    table.insert(rval, '"' .. json_private.encodeString(i) .. '":' .. json.encode(j))
                end
            end
            for i = 1, #needMap do
                local kk = needMap[i]
                local vv = v[kk]
                if isEncodable(kk) and isEncodable(vv) then
                    table.insert(rval, '"' .. json_private.encodeString(kk) .. '":' .. json.encode(vv))
                end
            end
        end
        if tType == "array" or tType == "hashset" then
            return "[" .. table.concat(rval, ",") .. "]"
        else
            return "{" .. table.concat(rval, ",") .. "}"
        end
    end

    -- Handle null values
    if vtype == "function" and v == json.null then
        return "null"
    end

    assert(false, "encode attempt to encode unsupported type " .. vtype .. ":" .. tostring(v))
end
function avoidLoopOver()
    index = index + 1
    if index > 1000 then
        assert(false, "stack overflow")
    end
end
function getTableType(t)
    if not t then
        return nil
    end
    local meta = getmetatable(t)
    if (meta.__genericT__) then
        if (meta.__genericTKey__) then
            if (meta.__genericTValue__) then
                return "dictionary"
            else
                return "hashset"
            end
        else
            return "array"
        end
    else
        return nil
    end
end
function checkAttributeInfo(t, map, needMap)
    local base, meta, fields, properties, attributeName
    base = t
    meta = getmetatable(t)
    repeat
        avoidLoopOver()
        if (meta and meta.__metadata__) then
            fields = meta.__metadata__.fields
            if (fields) then
                for _, v in pairs(fields) do
                    for i = 4, #v do
                        attributeName = getmetatable(v[i]).__name
                        if (attributeName == bsonIgnore) then
                            table.insert(map, v[1])
                        elseif attributeName == bsonRequired then
                            table.insert(needMap, v[1])
                        end
                    end
                end
            end
        end
        if (meta and meta.__metadata__) then
            properties = meta.__metadata__.properties
            if (properties) then
                for _, v in pairs(properties) do
                    for i = 5, #v do
                        attributeName = getmetatable(v[i]).__name
                        if (attributeName == bsonIgnore) then
                            table.insert(map, v[1])
                        elseif attributeName == bsonRequired then
                            table.insert(needMap, v[1])
                        end
                    end
                end
            end
        end
        base = System.base(base)
        if (not base or not base.__name__) then
            break
        end
        meta = base
    until false
end
--- Decodes a JSON string and returns the decoded value as a Lua data structure / value.
-- @param s The string to scan.
-- @param startPos Optional starting position where the JSON string is located. Defaults to 1.
-- @param Lua object, number The object that was scanned, as a Lua table / string / number / boolean or nil,
-- and the position of the first character after
-- the scanned JSON object.
function json.decode(s, startPos)
    startPos = startPos and startPos or 1
    startPos = decode_scanWhitespace(s, startPos)
    assert(startPos <= string.len(s), "Unterminated JSON encoded object found at position in [" .. s .. "]")
    local curChar = string.sub(s, startPos, startPos)
    -- Object
    if curChar == "{" then
        return decode_scanObject(s, startPos)
    end
    -- Array
    if curChar == "[" then
        return decode_scanArray(s, startPos)
    end
    -- Number
    if string.find("+-0123456789.e", curChar, 1, true) then
        return decode_scanNumber(s, startPos)
    end
    -- String
    if curChar == [["]] or curChar == [[']] then
        return decode_scanString(s, startPos)
    end
    if string.sub(s, startPos, startPos + 1) == "/*" then
        return json.decode(s, decode_scanComment(s, startPos))
    end
    -- Otherwise, it must be a constant
    return decode_scanConstant(s, startPos)
end

--- The null function allows one to specify a null value in an associative array (which is otherwise
-- discarded if you set the value with 'nil' in Lua. Simply set t = { first=json.null }
function json.null()
    return json.null -- so json.null() will also return null ;-)
end
-----------------------------------------------------------------------------
-- Internal, PRIVATE functions.
-- Following a Python-like convention, I have prefixed all these 'PRIVATE'
-- functions with an underscore.
-----------------------------------------------------------------------------

--- Scans an array from JSON into a Lua object
-- startPos begins at the start of the array.
-- Returns the array and the next starting position
-- @param s The string being scanned.
-- @param startPos The starting position for the scan.
-- @return table, int The scanned array as a table, and the position of the next character to scan.
function decode_scanArray(s, startPos)
    local array = {} -- The return value
    local stringLen = string.len(s)
    local objectType
    assert(
        string.sub(s, startPos, startPos) == "[",
        "decode_scanArray called but array does not start at position " .. startPos .. " in string:\n" .. s
    )
    startPos = startPos + 1
    -- Infinite loop for array elements
    local index = 1
    repeat
        startPos = decode_scanWhitespace(s, startPos)
        assert(startPos <= stringLen, "JSON String ended unexpectedly scanning array.")
        local curChar = string.sub(s, startPos, startPos)
        if (curChar == "]") then
            array = setObjectType(array,objectType)
            return array, startPos + 1
        end
        if (curChar == "\"") then
            assert(startPos <= stringLen, "JSON string ended unexpectedly scanning object.")
            -- Scan the key
            local key
            key, startPos = json.decode(s, startPos)
            assert(startPos <= stringLen, "JSON string ended unexpectedly searching for value of key " .. key)
            startPos = decode_scanWhitespace(s, startPos)
            assert(startPos <= stringLen, "JSON string ended unexpectedly searching for value of key " .. key)
            assert(string.sub(s, startPos, startPos) == ":", "JSON object key-value assignment mal-formed at " .. startPos)
            startPos = decode_scanWhitespace(s, startPos + 1)
            assert(startPos <= stringLen, "JSON string ended unexpectedly searching for value of key " .. key)
            local value
            value, startPos = json.decode(s, startPos)
            if key =="_t" then
                objectType = value
            end
        else
            if (curChar == ",") then
                startPos = decode_scanWhitespace(s, startPos + 1)
            end
            assert(startPos <= stringLen, "JSON String ended unexpectedly scanning array.")
            local object
            object, startPos = json.decode(s, startPos)
            array[index] = object
            index = index + 1
        end
    until false
end

--- Scans a comment and discards the comment.
-- Returns the position of the next character following the comment.
-- @param string s The JSON string to scan.
-- @param int startPos The starting position of the comment
function decode_scanComment(s, startPos)
    assert(
        string.sub(s, startPos, startPos + 1) == "/*",
        "decode_scanComment called but comment does not start at position " .. startPos
    )
    local endPos = string.find(s, "*/", startPos + 2)
    assert(endPos ~= nil, "Unterminated comment in string at " .. startPos)
    return endPos + 2
end

--- Scans for given constants: true, false or null
-- Returns the appropriate Lua type, and the position of the next character to read.
-- @param s The string being scanned.
-- @param startPos The position in the string at which to start scanning.
-- @return object, int The object (true, false or nil) and the position at which the next character should be
-- scanned.
function decode_scanConstant(s, startPos)
    local consts = {["true"] = true, ["false"] = false, ["null"] = nil}
    local constNames = {"true", "false", "null"}

    for i, k in pairs(constNames) do
        if string.sub(s, startPos, startPos + string.len(k) - 1) == k then
            return consts[k], startPos + string.len(k)
        end
    end
    assert(nil, "Failed to scan constant from string " .. s .. " at starting position " .. startPos)
end

--- Scans a number from the JSON encoded string.
-- (in fact, also is able to scan numeric +- eqns, which is not
-- in the JSON spec.)
-- Returns the number, and the position of the next character
-- after the number.
-- @param s The string being scanned.
-- @param startPos The position at which to start scanning.
-- @return number, int The extracted number and the position of the next character to scan.
function decode_scanNumber(s, startPos)
    local endPos = startPos + 1
    local stringLen = string.len(s)
    local acceptableChars = "+-0123456789.e"
    while (string.find(acceptableChars, string.sub(s, endPos, endPos), 1, true) and endPos <= stringLen) do
        endPos = endPos + 1
    end
    -- local stringValue = 'return ' .. string.sub(s, startPos, endPos - 1)
    -- local stringEval = loadstring(stringValue)
    -- assert(stringEval, 'Failed to scan number [ ' .. stringValue .. '] in JSON string at position ' .. startPos .. ' : ' .. endPos)
    local numberValue = string.sub(s, startPos, endPos - 1)
    return tonumber(numberValue), endPos
end

--- Scans a JSON object into a Lua object.
-- startPos begins at the start of the object.
-- Returns the object and the next starting position.
-- @param s The string being scanned.
-- @param startPos The starting position of the scan.
-- @return table, int The scanned object as a table and the position of the next character to scan.
function decode_scanObject(s, startPos)
    local object = {}
    local stringLen = string.len(s)
    local key, value,objectType
    assert(
        string.sub(s, startPos, startPos) == "{",
        "decode_scanObject called but object does not start at position " .. startPos .. " in string:\n" .. s
    )
    startPos = startPos + 1
    repeat
        startPos = decode_scanWhitespace(s, startPos)
        assert(startPos <= stringLen, "JSON string ended unexpectedly while scanning object.")
        local curChar = string.sub(s, startPos, startPos)
        if (curChar == "}") then
            object = setObjectType(object,objectType)
            return object, startPos + 1
        end
        if (curChar == ",") then
            startPos = decode_scanWhitespace(s, startPos + 1)
        end
        assert(startPos <= stringLen, "JSON string ended unexpectedly scanning object.")
        -- Scan the key
        key, startPos = json.decode(s, startPos)
        assert(startPos <= stringLen, "JSON string ended unexpectedly searching for value of key " .. key)
        startPos = decode_scanWhitespace(s, startPos)
        assert(startPos <= stringLen, "JSON string ended unexpectedly searching for value of key " .. key)
        assert(string.sub(s, startPos, startPos) == ":", "JSON object key-value assignment mal-formed at " .. startPos)
        startPos = decode_scanWhitespace(s, startPos + 1)
        assert(startPos <= stringLen, "JSON string ended unexpectedly searching for value of key " .. key)
        value, startPos = json.decode(s, startPos)
        if key =="_t" then
            objectType = value
        else
            object[key] = value
        end
    until false -- infinite loop while key-value pairs are found
end

function setObjectType(t, typeStr)
    if not typeStr then
        return t
    end
        t = setClassType(t, typeStr)
        return t
end
local getGenericTtype

function setClassType(t, name)
    if not t then
        return nil
    end
    local meta = System.getClass(name)
    if meta then
        return setmetatable(t, meta)
    else
        local obj
        local mapMeta = json_private.attributeMap[name]
        if mapMeta then
            obj = setmetatable(t, mapMeta)
        else
            mapMeta = getGenericTtype(name)
            json_private.attributeMap[name] = mapMeta
            obj = setmetatable(t, mapMeta)
        end
        --后处理
        if (mapMeta.__genericT__) then
            if (mapMeta.__genericTKey__) then
                if (mapMeta.__genericTValue__) then
                    --dictionary
                    if (mapMeta.__genericTKey__.__name__ ~= "System.String") then
                        local newT = {}
                        for k, v in pairs(obj) do
                            local i = tonumber(k)
                            newT[i] = v
                        end
                        obj = setmetatable(newT, mapMeta)
                    end
                else
                    --hashset
                    local newT = {}
                    newT = setmetatable(newT, mapMeta)
                    for _, v in pairs(obj) do
                        newT:Add(v)
                    end
                    obj = newT
                end
            else
                --array/list
            end
        end
        return obj
    end
end
getGenericTtype = function(name)
    avoidLoopOver()
    local typeBase, typeT
    local arr = name:Split("`", 2)
    if (#arr > 1) then
        typeBase = arr[1]
        local s = arr[2]
        typeT = string.sub(s, string.find(s, "%[") + 1, string.find(s, "%]$") - 1)
        local tArr = typeT:Split(",")
        local tTable = {}
        for k, v in pairs(tArr) do
            tTable[k] = getGenericTtype(v)
        end
        return System.getClass(typeBase)(table.unpack(tTable))
    else
        if (name:EndsWith("[]")) then
            typeBase = "System.Array"
            typeT = string.sub(name, 1, string.find(name, "%[") - 1)
            return System.getClass(typeBase)(getGenericTtype(typeT))
        else
            return System.getClass(name)
        end
    end
end
-- START SoniEx2
-- Initialize some things used by decode_scanString
-- You know, for efficiency
local escapeSequences = {
    ["\\t"] = "\t",
    ["\\f"] = "\f",
    ["\\r"] = "\r",
    ["\\n"] = "\n",
    ["\\b"] = "\b"
}
setmetatable(
    escapeSequences,
    {
        __index = function(t, k)
            -- skip "\" aka strip escape
            return string.sub(k, 2)
        end
    }
)
-- END SoniEx2

--- Scans a JSON string from the opening inverted comma or single quote to the
-- end of the string.
-- Returns the string extracted as a Lua string,
-- and the position of the next non-string character
-- (after the closing inverted comma or single quote).
-- @param s The string being scanned.
-- @param startPos The starting position of the scan.
-- @return string, int The extracted string as a Lua string, and the next character to parse.
function decode_scanString(s, startPos)
    assert(startPos, "decode_scanString(..) called without start position")
    local startChar = string.sub(s, startPos, startPos)
    -- START SoniEx2
    -- PS: I don't think single quotes are valid JSON
    assert(startChar == [["]] or startChar == [[']], "decode_scanString called for a non-string")
    --assert(startPos, "String decoding failed: missing closing " .. startChar .. " for string at position " .. oldStart)
    local t = {}
    local i, j = startPos, startPos
    while string.find(s, startChar, j + 1) ~= j + 1 do
        local oldj = j
        i, j = string.find(s, "\\.", j + 1)
        local x, y = string.find(s, startChar, oldj + 1)
        if not i or x < i then
            i, j = x, y - 1
        end
        table.insert(t, string.sub(s, oldj + 1, i - 1))
        if string.sub(s, i, j) == "\\u" then
            local a = string.sub(s, j + 1, j + 4)
            j = j + 4
            local n = tonumber(a, 16)
            assert(n, "String decoding failed: bad Unicode escape " .. a .. " at position " .. i .. " : " .. j)
            -- math.floor(x/2^y) == lazy right shift
            -- a % 2^b == bitwise_and(a, (2^b)-1)
            -- 64 = 2^6
            -- 4096 = 2^12 (or 2^6 * 2^6)
            local x
            if n < 0x80 then
                x = string.char(n % 0x80)
            elseif n < 0x800 then
                -- [110x xxxx] [10xx xxxx]
                x = string.char(0xC0 + (math.floor(n / 64) % 0x20), 0x80 + (n % 0x40))
            else
                -- [1110 xxxx] [10xx xxxx] [10xx xxxx]
                x =
                    string.char(
                    0xE0 + (math.floor(n / 4096) % 0x10),
                    0x80 + (math.floor(n / 64) % 0x40),
                    0x80 + (n % 0x40)
                )
            end
            table.insert(t, x)
        else
            table.insert(t, escapeSequences[string.sub(s, i, j)])
        end
    end
    table.insert(t, string.sub(j, j + 1))
    assert(
        string.find(s, startChar, j + 1),
        "String decoding failed: missing closing " ..
            startChar .. " at position " .. j .. "(for string at position " .. startPos .. ")"
    )
    return table.concat(t, ""), j + 2
    -- END SoniEx2
end

--- Scans a JSON string skipping all whitespace from the current start position.
-- Returns the position of the first non-whitespace character, or nil if the whole end of string is reached.
-- @param s The string being scanned
-- @param startPos The starting position where we should begin removing whitespace.
-- @return int The first position where non-whitespace was encountered, or string.len(s)+1 if the end of string
-- was reached.
function decode_scanWhitespace(s, startPos)
    local whitespace = " \n\r\t"
    local stringLen = string.len(s)
    while (string.find(whitespace, string.sub(s, startPos, startPos), 1, true) and startPos <= stringLen) do
        startPos = startPos + 1
    end
    return startPos
end

--- Encodes a string to be JSON-compatible.
-- This just involves back-quoting inverted commas, back-quotes and newlines, I think ;-)
-- @param s The string to return as a JSON encoded (i.e. backquoted string)
-- @return The string appropriately escaped.

local escapeList = {
    ['"'] = '\\"',
    ["\\"] = "\\\\",
    ["/"] = "\\/",
    ["\b"] = "\\b",
    ["\f"] = "\\f",
    ["\n"] = "\\n",
    ["\r"] = "\\r",
    ["\t"] = "\\t"
}

function json_private.encodeString(s)
    local s = tostring(s)
    return s:gsub(
        ".",
        function(c)
            return escapeList[c]
        end
    ) -- SoniEx2: 5.0 compat
end

-- Determines whether the given Lua type is an array or a table / dictionary.
-- We consider any table an array if it has indexes 1..n for its n items, and no
-- other data in the table.
-- I think this method is currently a little 'flaky', but can't think of a good way around it yet...
-- @param t The table to evaluate as an array
-- @return boolean, number True if the table can be represented as an array, false otherwise. If true,
-- the second returned value is the maximum
-- number of indexed elements in the array.
function isArray(t)
    -- Next we count all the elements, ensuring that any non-indexed elements are not-encodable
    -- (with the possible exception of 'n')
    if (t == json.EMPTY_ARRAY) then
        return true, 0
    end
    if (t == json.EMPTY_OBJECT) then
        return false
    end

    local maxIndex = 0
    for k, v in pairs(t) do
        if (type(k) == "number" and math.floor(k) == k and 1 <= k) then -- k,v is an indexed pair
            if (not isEncodable(v)) then
                return false
            end -- All array elements must be encodable
            maxIndex = math.max(maxIndex, k)
        else
            if (k == "n") then
                if v ~= (t.n or #t) then
                    return false
                end -- False if n does not hold the number of elements
            else -- Else of (k=='n')
                if isEncodable(v) then
                    return false
                end
            end -- End of (k~='n')
        end -- End of k,v not an indexed pair
    end -- End of loop across all pairs
    return true, maxIndex
end

--- Determines whether the given Lua object / table / variable can be JSON encoded. The only
-- types that are JSON encodable are: string, boolean, number, nil, table and json.null.
-- In this implementation, all other types are ignored.
-- @param o The object to examine.
-- @return boolean True if the object should be JSON encoded, false if it should be ignored.
function isEncodable(o)
    local t = type(o)
    return (t == "string" or t == "boolean" or t == "number" or t == "nil" or t == "table") or
        (t == "function" and o == json.null)
end
function table.unique(t, bArray)
    local check = {}
    local n = {}
    local idx = 1
    for k, v in pairs(t) do
        if not check[v] then
            if bArray then
                n[idx] = v
                idx = idx + 1
            else
                n[k] = v
            end
            check[v] = true
        end
    end
    return n
end
function IsVlaueInTable(t, v)
    if not t then
        return false
    end
    for _, vv in pairs(t) do
        if vv == v then
            return true
        end
    end
    return false
end
function IsKeyInTable(t, key)
    return not t and not t[key]
end
return json